WorldWideScience

Sample records for antiferromagnetic spin correlations

  1. Antiferromagnetic phase transition and spin correlations in NiO

    DEFF Research Database (Denmark)

    Chatterji, Tapan; McIntyre, G.J.; Lindgård, Per-Anker

    2009-01-01

    We have investigated the antiferromagnetic (AF) phase transition and spin correlations in NiO by high-temperature neutron diffraction below and above TN. We show that AF phase transition is a continuous second-order transition within our experimental resolution. The spin correlations manifested...... by the strong diffuse magnetic scattering persist well above TN530 K and could still be observed at T=800 K which is about 1.5TN. We argue that the strong spin correlations above TN are due to the topological frustration of the spins on a fcc lattice. The Néel temperature is substantially reduced...... by this process. We determined the critical exponents =0.328±0.002 and =0.64±0.03 and the Néel temperature TN=530±1 K. These critical exponents suggest that NiO should be regarded as a 3dXY system...

  2. Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite medium

    International Nuclear Information System (INIS)

    Sarmento, E.F.

    1981-01-01

    Results are found for the dynamical correlation functions (or its corresponding Green's functions) among any combination including operator pairs of electronic and nuclear spins in an antiferromagnet semi-infinite medium, at low temperatures T [pt

  3. Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite media

    International Nuclear Information System (INIS)

    Sarmento, E.F.

    1980-01-01

    Results are found for the correlation dynamic functions (or the correspondent green functions) between any combination including pairs of electronic anel nuclear spin operators in an antiferromagnet semi-infinite media., at low temperature T N . These correlation functions, are used to investigate, at the same time, the properties of surface spin waves in volume and surface. The dispersion relatons of nuclear and electronic spin waves coupled modes, in surface are found, resolving a system of linearized equatons of spin operators a system of linearized equations of spin operators. (author) [pt

  4. Magnetic correlations and quantum criticality in the insulating antiferromagnetic, insulating spin liquid, renormalized Fermi liquid, and metallic antiferromagnetic phases of the Mott system V2O3

    Science.gov (United States)

    Bao, Wei; Broholm, C.; Aeppli, G.; Carter, S. A.; Dai, P.; Rosenbaum, T. F.; Honig, J. M.; Metcalf, P.; Trevino, S. F.

    1998-11-01

    Magnetic correlations in all four phases of pure and doped vanadium sesquioxide (V2O3) have been examined by magnetic thermal-neutron scattering. Specifically, we have studied the antiferromagnetic and paramagnetic phases of metallic V2-yO3, the antiferromagnetic insulating and paramagnetic metallic phases of stoichiometric V2O3, and the antiferromagnetic and paramagnetic phases of insulating V1.944Cr0.056O3. While the antiferromagnetic insulator can be accounted for by a localized Heisenberg spin model, the long-range order in the antiferromagnetic metal is an incommensurate spin-density wave, resulting from a Fermi surface nesting instability. Spin dynamics in the strongly correlated metal are dominated by spin fluctuations with a ``single lobe'' spectrum in the Stoner electron-hole continuum. Furthermore, our results in metallic V2O3 represent an unprecedentedly complete characterization of the spin fluctuations near a metallic quantum critical point, and provide quantitative support for the self-consistent renormalization theory for itinerant antiferromagnets in the small moment limit. Dynamic magnetic correlations for ħωantiferromagnetic insulator, from the paramagnetic metal and the paramagnetic insulator, introduces a sudden switching of magnetic correlations to a different spatial periodicity which indicates a sudden change in the underlying spin Hamiltonian. To describe this phase transition and also the unusual short-range order in the paramagnetic state, it seems necessary to take into account the orbital degrees of freedom associated with the degenerate d orbitals at the Fermi level in V2O3.

  5. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien

    2015-05-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  6. Antiferromagnetic spin Seebeck effect.

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand

    2016-03-03

    We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2. A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF2(110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2–80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9T) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.

  7. Quantum corrections to the spin-correlation function and the spin-stiffness constant in a two-dimensional Heisenberg antiferromagnet at zero temperature

    International Nuclear Information System (INIS)

    Igarashi, J.; Watabe, A.

    1991-01-01

    Quantum corrections to the longitudinal spin-correlation function and the spin-stiffness constant are calculated up to 1/(2S) 2 in a two-dimensional Heisenberg antiferromagnet at zero temperature by using the Holstein-Primakoff transformation. The equal-time longitudinal spin-correlation function is found to compensate almost entirely the reduction caused by the second-order correction in the transverse spin-correlation function, making the spherically averaged correlation function very close to the value given by linear spin-wave theory. In the spin-stiffness constant, a partial cancellation is found between the ''paramagnetic'' and ''diamagnetic'' terms, leading to a small second-order correction

  8. Spin structures in antiferromagnetic nanoparticles

    DEFF Research Database (Denmark)

    Brok, Erik

    a detailed knowledge of it can be important for applications of antiferromagnetic nanoparticles for example combined with ferromagnetic nanoparticles in nanocomposite devices. In this thesis the magnetic structure, in particular the orientation of the spins in the antiferromagnetic sublattices......, proposed to explain the unusual magnetic properties of the mineral. In summary the thesis have demonstrated methods for investigation of spin structures in magnetic nanoparticles. In particular, the classical model of the temperature dependence of canted spin structures sucessfully explains many...... experimental observations of anomalous temperature dependence in nanoparticle and bulk systems. Morover, XY Z neutron polarisation analysis have been demonstrated to be an effective way of investigating the magnetic properties of antiferromagnetic nanoparticles, significantly improving the unpolarised neutron...

  9. Spin Structure Analyses of Antiferromagnets

    International Nuclear Information System (INIS)

    Chung, Jae Ho; Song, Young Sang; Lee, Hak Bong

    2010-05-01

    We have synthesized series of powder sample of incommensurate antiferromagnetic multiferroics, (Mn, Co)WO 4 and Al doped Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 , incommensurate antiferromagnetic multiferroics. Their spin structure was studied by using the HRPD. In addition, we have synthesized series of crystalline samples of incommensurate multiferroics, (Mn, Co)WO 4 and olivines. Their spin structure was investigated using neutron diffraction under high magnetic field. As a result, we were able to draw the phase diagram of (Mn, Co)WO 4 as a function of composition and temperature. We learned the how the spin structure changes with increased ionic substitution. Finally we have drawn the phase diagram of the multicritical olivine Mn2SiS4/Mn2GeS4 as a function of filed and temperature through the spin structure studies

  10. Magnetic order, magnetic correlations, and spin dynamics in the pyrochlore antiferromagnet Er2Ti2O7

    Science.gov (United States)

    Dalmas de Réotier, P.; Yaouanc, A.; Chapuis, Y.; Curnoe, S. H.; Grenier, B.; Ressouche, E.; Marin, C.; Lago, J.; Baines, C.; Giblin, S. R.

    2012-09-01

    Er2Ti2O7 is believed to be a realization of an XY antiferromagnet on a frustrated lattice of corner-sharing regular tetrahedra. It is presented as an example of the order-by-disorder mechanism in which fluctuations lift the degeneracy of the ground state, leading to an ordered state. Here we report detailed measurements of the low-temperature magnetic properties of Er2Ti2O7, which displays a second-order phase transition at TN≃1.2 K with coexisting short- and long-range orders. Magnetic susceptibility studies show that there is no spin-glass-like irreversible effect. Heat capacity measurements reveal that the paramagnetic critical exponent is typical of a 3-dimensional XY magnet while the low-temperature specific heat sets an upper limit on the possible spin-gap value and provides an estimate for the spin-wave velocity. Muon spin relaxation measurements show the presence of spin dynamics in the nanosecond time scale down to 21 mK. This time range is intermediate between the shorter time characterizing the spin dynamics in Tb2Sn2O7, which also displays long- and short-range magnetic order, and the time scale typical of conventional magnets. Hence the ground state is characterized by exotic spin dynamics. We determine the parameters of a symmetry-dictated Hamiltonian restricted to the spins in a tetrahedron, by fitting the paramagnetic diffuse neutron scattering intensity for two reciprocal lattice planes. These data are recorded in a temperature region where the assumption that the correlations are limited to nearest neighbors is fair.

  11. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-02-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  12. Spin correlations in the 2D Heisenberg antiferromagnet Sr2CuO2Cl2: Neutron scattering, Monte Carlo simulation, and theory

    International Nuclear Information System (INIS)

    Greven, M.; Birgeneau, R.J.; Endoh, Y.; Kastner, M.A.; Keimer, B.; Matsuda, M.; Shirane, G.; Thurston, T.R.

    1994-01-01

    We report a neutron scattering study of the spin correlations in the model 2D, S=1/2, square-lattice Heisenberg antiferromagnetic Sr 2 CuO 2 Cl 2 . The spin correlation lengths obtained agree quantitatively with values deduced from Monte Carlo simulations over a wide range of temperature. The combined data, which cover the length scale from 1 to 200 lattice constants, are predicted accurately with no adjustable parameters by renormalized classical theory for the quantum nonlinear sigma model

  13. Magnetic correlations and quantum criticality in the insulating antiferromagnetic, insulating spin liquid, renormalized Fermi liquid, and metallic antiferromagnetic phases of the Mott system V{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bao, W. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Broholm, C. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)]|[Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Aeppli, G. [NEC, 4 Independence Way, Princeton, New Jersey 08540 (United States); Carter, S.A. [Department of Physics, University of California, Santa Cruz, California 95064 (United States); Dai, P. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Rosenbaum, T.F. [James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States); Honig, J.M.; Metcalf, P. [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Trevino, S.F. [United States Army Research Laboratory, Adelphi, Maryland 20783 (United States)]|[Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    1998-11-01

    Magnetic correlations in all four phases of pure and doped vanadium sesquioxide (V{sub 2}O{sub 3}) have been examined by magnetic thermal-neutron scattering. Specifically, we have studied the antiferromagnetic and paramagnetic phases of metallic V{sub 2{minus}y}O{sub 3}, the antiferromagnetic insulating and paramagnetic metallic phases of stoichiometric V{sub 2}O{sub 3}, and the antiferromagnetic and paramagnetic phases of insulating V{sub 1.944}Cr{sub 0.056}O{sub 3}. While the antiferromagnetic insulator can be accounted for by a localized Heisenberg spin model, the long-range order in the antiferromagnetic metal is an incommensurate spin-density wave, resulting from a Fermi surface nesting instability. Spin dynamics in the strongly correlated metal are dominated by spin fluctuations with a {open_quotes}single lobe{close_quotes} spectrum in the Stoner electron-hole continuum. Furthermore, our results in metallic V{sub 2}O{sub 3} represent an unprecedentedly complete characterization of the spin fluctuations near a metallic quantum critical point, and provide quantitative support for the self-consistent renormalization theory for itinerant antiferromagnets in the small moment limit. Dynamic magnetic correlations for {h_bar}{omega}{lt}k{sub B}T in the paramagnetic insulator carry substantial magnetic spectral weight. However, they are extremely short-ranged, extending only to the nearest neighbors. The phase transition to the antiferromagnetic insulator, from the paramagnetic metal and the paramagnetic insulator, introduces a sudden switching of magnetic correlations to a different spatial periodicity which indicates a sudden change in the underlying spin Hamiltonian. To describe this phase transition and also the unusual short-range order in the paramagnetic state, it seems necessary to take into account the orbital degrees of freedom associated with the degenerate {ital d} orbitals at the Fermi level in V{sub 2}O{sub 3}. {copyright} {ital 1998} {ital The American

  14. Magnetic correlations of the quasi-one-dimensional half-integer spin-chain antiferromagnets Sr$M_2$V$_2$O$_8$ ($M$ = Co, Mn)

    OpenAIRE

    Bera, A. K.; Lake, B.; Stein, W. -D.; Zander, S.

    2014-01-01

    Magnetic correlations of two iso-structural quasi-one-dimensional (1D) antiferromagnetic spin-chain compounds Sr$M_2$V$_2$O$_8$ ($M$ = Co, Mn) have been investigated by magnetization and powder neutron diffraction. Two different collinear antiferromagnetic (AFM) structures, characterized by the propagation vectors, $k$ = (0 0 1) and $k$ = (0 0 0), have been found below $\\sim$ 5.2 K and $\\sim$ 42.2 K for the Co- and Mn-compounds, respectively. For the Mn-compound, AFM chains (along the $c$ axi...

  15. Superconductivity, Antiferromagnetism, and Kinetic Correlation in Strongly Correlated Electron Systems

    Directory of Open Access Journals (Sweden)

    Takashi Yanagisawa

    2015-01-01

    Full Text Available We investigate the ground state of two-dimensional Hubbard model on the basis of the variational Monte Carlo method. We use wave functions that include kinetic correlation and doublon-holon correlation beyond the Gutzwiller ansatz. It is still not clear whether the Hubbard model accounts for high-temperature superconductivity. The antiferromagnetic correlation plays a key role in the study of pairing mechanism because the superconductive phase exists usually close to the antiferromagnetic phase. We investigate the stability of the antiferromagnetic state when holes are doped as a function of the Coulomb repulsion U. We show that the antiferromagnetic correlation is suppressed as U is increased exceeding the bandwidth. High-temperature superconductivity is possible in this region with enhanced antiferromagnetic spin fluctuation and pairing interaction.

  16. Antiferromagnetic spin correlations in (Nd,Pr)2-xCexCuO4

    International Nuclear Information System (INIS)

    Thurston, T.R.; Matsuda, M.; Kakurai, K.; Yamada, K.; Endoh, Y.; Birgeneau, R.J.; Gehring, P.M.; Hidaka, Y.; Kastner, M.A.; Murakami, T.; Shirane, G.

    1990-01-01

    Neutron-scattering measurements have been performed on (Nd,Pr) 2-x Ce x CuO 4 (0.0 2 CuO 4 albeit with renormalized spin stiffness constants ρ s . Thus, in the nonsuperconducting doping regime the hole- and electron-doped systems exhibit analogous magnetic behavior except for the drastically different dopant-concentration scales for the destruction of magnetic order

  17. Antiferromagnetic Spin Wave Field-Effect Transistor

    Science.gov (United States)

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-01-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale. PMID:27048928

  18. Heat-driven spin torques in antiferromagnets

    Science.gov (United States)

    Białek, Marcin; Bréchet, Sylvain; Ansermet, Jean-Philippe

    2018-04-01

    Heat-driven magnetization damping, which is a linear function of a temperature gradient, is predicted in antiferromagnets by considering the sublattice dynamics subjected to a heat-driven spin torque. This points to the possibility of achieving spin torque oscillator behavior. The model is based on the magnetic Seebeck effect acting on sublattices which are exchange coupled. The heat-driven spin torque is estimated and the feasibility of detecting this effect is discussed.

  19. Hole pairing induced by antiferromagnetic spin fluctuations

    International Nuclear Information System (INIS)

    Su, Z.B.; Yu Lu; Dong, J.M.; Tosatti, E.

    1987-08-01

    The effective interaction induced by antiferromagnetic spin fluctuations is considered in the random phase approximation in the context of the recently discovered high T c oxide superconductors. This effective attraction favours a triplet pairing of holes. The implications of such pairing mechanism are discussed in connection with the current experimental observations. (author). 30 refs, 2 figs

  20. Spin transport and spin torque in antiferromagnetic devices

    Science.gov (United States)

    Železný, J.; Wadley, P.; Olejník, K.; Hoffmann, A.; Ohno, H.

    2018-03-01

    Ferromagnets are key materials for sensing and memory applications. In contrast, antiferromagnets, which represent the more common form of magnetically ordered materials, have found less practical application beyond their use for establishing reference magnetic orientations via exchange bias. This might change in the future due to the recent progress in materials research and discoveries of antiferromagnetic spintronic phenomena suitable for device applications. Experimental demonstration of the electrical switching and detection of the Néel order open a route towards memory devices based on antiferromagnets. Apart from the radiation and magnetic-field hardness, memory cells fabricated from antiferromagnets can be inherently multilevel, which could be used for neuromorphic computing. Switching speeds attainable in antiferromagnets far exceed those of ferromagnetic and semiconductor memory technologies. Here, we review the recent progress in electronic spin-transport and spin-torque phenomena in antiferromagnets that are dominantly of the relativistic quantum-mechanical origin. We discuss their utility in pure antiferromagnetic or hybrid ferromagnetic/antiferromagnetic memory devices.

  1. Spin Transport in Ferromagnetic and Antiferromagnetic Textures

    KAUST Repository

    Akosa, Collins A.

    2016-12-07

    In this dissertation, we provide an accurate description of spin transport in magnetic textures and in particular, we investigate in detail, the nature of spin torque and magnetic damping in such systems. Indeed, as will be further discussed in this thesis, the current-driven velocity of magnetic textures is related to the ratio between the so-called non-adiabatic torque and magnetic damping. Uncovering the physics underlying these phenomena can lead to the optimal design of magnetic systems with improved efficiency. We identified three interesting classes of systems which have attracted enormous research interest (i) Magnetic textures in systems with broken inversion symmetry: We investigate the nature of magnetic damping in non-centrosymmetric ferromagnets. Based on phenomenological and microscopic derivations, we show that the magnetic damping becomes chiral, i.e. depends on the chirality of the magnetic texture. (ii) Ferromagnetic domain walls, skyrmions and vortices: We address the physics of spin transport in sharp disordered magnetic domain walls and vortex cores. We demonstrate that upon spin-independent scattering, the non-adiabatic torque can be significantly enhanced. Such an enhancement is large for vortex cores compared to transverse domain walls. We also show that the topological spin currents owing in these structures dramatically enhances the non-adiabaticity, an effect unique to non-trivial topological textures (iii) Antiferromagnetic skyrmions: We extend this study to antiferromagnetic skyrmions and show that such an enhanced topological torque also exist in these systems. Even more interestingly, while such a non-adiabatic torque inuences the undesirable transverse velocity of ferromagnetic skyrmions, in antiferromagnetic skyrmions, the topological non-adiabatic torque directly determines the longitudinal velocity. As a consequence, scaling down the antiferromagnetic skyrmion results in a much more efficient spin torque.

  2. High-field spin dynamics of antiferromagnetic quantum spin chains

    DEFF Research Database (Denmark)

    Enderle, M.; Regnault, L.P.; Broholm, C.

    2000-01-01

    present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights......The characteristic internal order of macroscopic quantum ground states in one-dimensional spin systems is usually not directly accessible, but reflected in the spin dynamics and the field dependence of the magnetic excitations. In high magnetic fields quantum phase transitions are expected. We...

  3. Frustrated spin-1/2 ladder with ferro- and antiferromagnetic legs

    Science.gov (United States)

    Maiti, Debasmita; Dey, Dayasindhu; Kumar, Manoranjan

    2018-01-01

    Two-leg spin-1/2 ladder systems consisting of a ferromagnetic leg and an antiferromagnetic leg are considered where the spins on the legs interact through antiferromagnetic rung couplings J1 . These ladders can have two geometrical arrangements either zigzag or normal ladder and these systems are frustrated irrespective of their geometry. This frustration gives rise to incommensurate spin density wave, dimer and spin fluid phases in the ground state. The magnetization in the systems decreases linearly with J12, and the systems show an incommensurate phase for 0.0 spin-spin correlation functions in the incommensurate phase follow power law decay which is very similar to Heisenberg antiferromagnetic chain in external magnetic field. In large J1 limit, the normal ladder behaves like a collection of singlet dimers, whereas the zigzag ladder behaves as a one dimensional spin-1/2 antiferromagnetic chain.

  4. Spin-Mechanical Inertia in Antiferromagnet

    Science.gov (United States)

    Cheng, Ran; Wu, Xiaochuan; Xiao, Di

    Interplay between spin dynamics and mechanical motions is responsible for numerous striking phenomena, which has shaped a rapidly expanding field known as spin-mechanics. The guiding principle of this field has been the conservation of angular momentum that involves both quantum spins and classical mechanical rotations. However, in an antiferromagnet, the macroscopic magnetization vanishes while the order parameter (Néel order) does not carry an angular momentum. It is therefore not clear whether the order parameter dynamics has any mechanical consequence as its ferromagnetic counterparts. Here we demonstrate that the Néel order dynamics affects the mechanical motion of a rigid body by modifying its inertia tensor in the presence of strong magnetocrystalline anisotropy. This effect depends on temperature when magnon excitations are considered. Such a spin-mechanical inertia can produce measurable consequences at nanometer scales. Our discovery establishes spin-mechanical inertia as an essential ingredient to properly describe spin-mechanical effects in AFs, which supplements the known governing physics from angular momentum conservation. This work was supported by the DOE, Basic Energy Sciences, Grant No. DE-SC0012509. D.X. also acknowledges support from a Research Corporation for Science Advancement Cottrell Scholar Award.

  5. Robust spin transfer torque in antiferromagnetic tunnel junctions

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2017-04-18

    We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.

  6. Dynamics of antiferromagnetic skyrmion driven by the spin Hall effect

    Science.gov (United States)

    Jin, Chendong; Song, Chengkun; Wang, Jianbo; Liu, Qingfang

    2016-10-01

    Magnetic skyrmion moved by the spin-Hall effect is promising for the application of the generation racetrack memories. However, the Magnus force causes a deflected motion of skyrmion, which limits its application. Here, we create an antiferromagnetic skyrmion by injecting a spin-polarized pulse in the nanostripe and investigate the spin Hall effect-induced motion of antiferromagnetic skyrmion by micromagnetic simulations. In contrast to ferromagnetic skyrmion, we find that the antiferromagnetic skyrmion has three evident advantages: (i) the minimum driving current density of antiferromagnetic skyrmion is about two orders smaller than the ferromagnetic skyrmion; (ii) the velocity of the antiferromagnetic skyrmion is about 57 times larger than the ferromagnetic skyrmion driven by the same value of current density; (iii) antiferromagnetic skyrmion can be driven by the spin Hall effect without the influence of Magnus force. In addition, antiferromagnetic skyrmion can move around the pinning sites due to its property of topological protection. Our results present the understanding of antiferromagnetic skyrmion motion driven by the spin Hall effect and may also contribute to the development of antiferromagnetic skyrmion-based racetrack memories.

  7. Spin Currents and Spin Orbit Torques in Ferromagnets and Antiferromagnets

    Science.gov (United States)

    Hung, Yu-Ming

    This thesis focuses on the interactions of spin currents and materials with magnetic order, e.g., ferromagnetic and antiferromagnetic thin films. The spin current is generated in two ways. First by spin-polarized conduction-electrons associated with the spin Hall effect in heavy metals (HMs) and, second, by exciting spin-waves in ferrimagnetic insulators using a microwave frequency magnetic field. A conduction-electron spin current can be generated by spin-orbit coupling in a heavy non-magnetic metal and transfer its spin angular momentum to a ferromagnet, providing a means of reversing the magnetization of perpendicularly magnetized ultrathin films with currents that flow in the plane of the layers. The torques on the magnetization are known as spin-orbit torques (SOT). In the first part of my thesis project I investigated and contrasted the quasistatic (slowly swept current) and pulsed current-induced switching characteristics of micrometer scale Hall crosses consisting of very thin (thesis project studies and considers applications of SOT-driven domain wall (DW) motion in a perpendicularly magnetized ultrathin ferromagnet sandwiched between a heavy metal and an oxide. My experiment results demonstrate that the DW motion can be explained by a combination of the spin Hall effect, which generates a SOT, and Dzyaloshinskii-Moriya interaction, which stabilizes chiral Neel-type DW. Based on SOT-driven DW motion and magnetic coupling between electrically isolated ferromagnetic elements, I proposed a new type of spin logic devices. I then demonstrate the device operation by using micromagnetic modeling which involves studying the magnetic coupling induced by fringe fields from chiral DWs in perpendicularly magnetized nanowires. The last part of my thesis project reports spin transport and spin-Hall magnetoresistance (SMR) in yttrium iron garnet Y3Fe5O 12 (YIG)/NiO/Pt trilayers with varied NiO thickness. To characterize the spin transport through NiO we excite

  8. Spin Hall magnetoresistance in antiferromagnet/normal metal bilayers

    KAUST Repository

    Manchon, Aurelien

    2017-01-01

    We investigate the emergence of spin Hall magnetoresistance in a magnetic bilayer composed of a normal metal adjacent to an antiferromagnet. Based on a recently derived drift diffusion equation, we show that the resistance of the bilayer depends on the relative angle between the direction transverse to the current flow and the Néel order parameter. While this effect presents striking similarities with the spin Hall magnetoresistance recently reported in ferromagnetic bilayers, its physical origin is attributed to the anisotropic spin relaxation of itinerant spins in the antiferromagnet.

  9. Antiferromagnetic noise correlations in optical lattices

    DEFF Research Database (Denmark)

    Bruun, Niels Bohr International Academy, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark, Georg Morten; Syljuåsen, F. T.; Pedersen, K. G. L.

    2009-01-01

    We analyze how noise correlations probed by time-of-flight experiments reveal antiferromagnetic (AF) correlations of fermionic atoms in two-dimensional and three-dimensional optical lattices. Combining analytical and quantum Monte Carlo calculations using experimentally realistic parameters, we s...

  10. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2014-05-28

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  11. Spin waves in antiferromagnetic FeF2

    DEFF Research Database (Denmark)

    Hutchings, M T; Rainford, B.D.; Guggenheim, H J

    1970-01-01

    Spin-wave dispersion in antiferromagnetic FeF2 has been investigated by inelastic neutron scattering using a chopper time-of-flight spectrometer. The single mode observed has a relatively flat dispersion curve rising from 53 cm-1 at the zone centre to 79 cm-1 at the zone boundary. A spin...

  12. Spin transfer and spin pumping in disordered normal metal-antiferromagnetic insulator systems

    Science.gov (United States)

    Gulbrandsen, Sverre A.; Brataas, Arne

    2018-02-01

    We consider an antiferromagnetic insulator that is in contact with a metal. Spin accumulation in the metal can induce spin-transfer torques on the staggered field and on the magnetization in the antiferromagnet. These torques relate to spin pumping: the emission of spin currents into the metal by a precessing antiferromagnet. We investigate how the various components of the spin-transfer torque are affected by spin-independent disorder and spin-flip scattering in the metal. Spin-conserving disorder reduces the coupling between the spins in the antiferromagnet and the itinerant spins in the metal in a manner similar to Ohm's law. Spin-flip scattering leads to spin-memory loss with a reduced spin-transfer torque. We discuss the concept of a staggered spin current and argue that it is not a conserved quantity. Away from the interface, the staggered spin current varies around a 0 mean in an irregular manner. A network model explains the rapid decay of the staggered spin current.

  13. Role of the antiferromagnetic bulk spins in exchange bias

    Energy Technology Data Exchange (ETDEWEB)

    Schuller, Ivan K. [Center for Advanced Nanoscience and Physics Department, University of California San Diego, La Jolla, CA 92093 (United States); Morales, Rafael, E-mail: rafael.morales@ehu.es [Department of Chemical-Physics & BCMaterials, University of the Basque Country UPV/EHU (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Batlle, Xavier [Departament Física Fonamental and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, c/ Martí i Franqués s/n, 08028 Barcelona, Catalonia (Spain); Nowak, Ulrich [Department of Physics, University of Konstanz, 78464 Konstanz (Germany); Güntherodt, Gernot [Physics Institute (IIA), RWTH Aachen University, Campus RWTH-Melaten, 52074 Aachen (Germany)

    2016-10-15

    This “Critical Focused Issue” presents a brief review of experiments and models which describe the origin of exchange bias in epitaxial or textured ferromagnetic/antiferromagnetic bilayers. Evidence is presented which clearly indicates that inner, uncompensated, pinned moments in the bulk of the antiferromagnet (AFM) play a very important role in setting the magnitude of the exchange bias. A critical evaluation of the extensive literature in the field indicates that it is useful to think of this bulk, pinned uncompensated moments as a new type of a ferromagnet which has a low total moment, an ordering temperature given by the AFM Néel temperature, with parallel aligned moments randomly distributed on the regular AFM lattice. - Highlights: • We address the role of bulk antiferromagnetic spins in the exchange bias phenomenon. • Significant experiments on how bulk AFM spins determine exchange bias are highlighted. • We explain the model that accounts for experimental results.

  14. Spin Hall effects in metallic antiferromagnets – perspectives for future spin-orbitronics

    Directory of Open Access Journals (Sweden)

    Joseph Sklenar

    2016-05-01

    Full Text Available We investigate angular dependent spin-orbit torques from the spin Hall effect in a metallic antiferromagnet using the spin-torque ferromagnetic resonance technique. The large spin Hall effect exists in PtMn, a prototypical CuAu-I-type metallic antiferromagnet. By applying epitaxial growth, we previously reported an appreciable difference in spin-orbit torques for c- and a-axis orientated samples, implying anisotropic effects in magnetically ordered materials. In this work we demonstrate through bipolar-magnetic-field experiments a small but noticeable asymmetric behavior in the spin-transfer-torque that appears as a hysteresis effect. We also suggest that metallic antiferromagnets may be good candidates for the investigation of various unidirectional effects related to novel spin-orbitronics phenomena.

  15. Muon Spin Relaxation Evidence for the U(1) Quantum Spin-Liquid Ground State in the Triangular Antiferromagnet YbMgGaO_{4}.

    Science.gov (United States)

    Li, Yuesheng; Adroja, Devashibhai; Biswas, Pabitra K; Baker, Peter J; Zhang, Qian; Liu, Juanjuan; Tsirlin, Alexander A; Gegenwart, Philipp; Zhang, Qingming

    2016-08-26

    Muon spin relaxation (μSR) experiments on single crystals of the structurally perfect triangular antiferromagnet YbMgGaO_{4} indicate the absence of both static long-range magnetic order and spin freezing down to 0.048 K in a zero field. Below 0.4 K, the μ^{+} spin relaxation rates, which are proportional to the dynamic correlation function of the Yb^{3+} spins, exhibit temperature-independent plateaus. All these μSR results unequivocally support the formation of a gapless U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO_{4}.

  16. Pure spin current manipulation in antiferromagnetically exchange coupled heterostructures

    Science.gov (United States)

    Avilés-Félix, L.; Butera, A.; González-Chávez, D. E.; Sommer, R. L.; Gómez, J. E.

    2018-03-01

    We present a model to describe the spin currents generated by ferromagnet/spacer/ferromagnet exchange coupled trilayer systems and heavy metal layers with strong spin-orbit coupling. By exploiting the magnitude of the exchange coupling (oscillatory RKKY-like coupling) and the spin-flop transition in the magnetization process, it has been possible to produce spin currents polarized in arbitrary directions. The spin-flop transition of the trilayer system originates pure spin currents whose polarization vector depends on the exchange field and the magnetization equilibrium angles. We also discuss a protocol to control the polarization sign of the pure spin current injected into the metallic layer by changing the initial conditions of magnetization of the ferromagnetic layers previously to the spin pumping and inverse spin Hall effect experiments. The small differences in the ferromagnetic layers lead to a change in the magnetization vector rotation that permits the control of the sign of the induced voltage components due to the inverse spin Hall effect. Our results can lead to important advances in hybrid spintronic devices with new functionalities, particularly, the ability to control microscopic parameters such as the polarization direction and the sign of the pure spin current through the variation of macroscopic parameters, such as the external magnetic field or the thickness of the spacer in antiferromagnetic exchange coupled systems.

  17. Healing of defects in random antiferromagnetic spin chains

    Science.gov (United States)

    Vasseur, R.; Roshani, A.; Haas, S.; Saleur, H.

    2017-09-01

    We study the effects of a weakened link in random antiferromagnetic spin chains. We show that healing occurs, and that homogeneity is restored at low energy, in a way that is qualitatively similar to the fate of impurities in clean ferromagnetic spin chains, or in Luttinger liquids with attractive interactions. Healing in the random case occurs even without interactions, and is characteristic of the random singlet phase. Using real-space renormalization group and exact diagonalization methods, we characterize this universal healing crossover by studying the entanglement across the weak link. We identify a crossover healing length L\\star that separates a regime where the system is cut in half by the weak link from a fixed point where the spin chain is healed. Our results open the way to the study of impurity physics in disordered spin chains.

  18. Terahertz-Driven Nonlinear Spin Response of Antiferromagnetic Nickel Oxide

    Science.gov (United States)

    Baierl, S.; Mentink, J. H.; Hohenleutner, M.; Braun, L.; Do, T.-M.; Lange, C.; Sell, A.; Fiebig, M.; Woltersdorf, G.; Kampfrath, T.; Huber, R.

    2016-11-01

    Terahertz magnetic fields with amplitudes of up to 0.4 Tesla drive magnon resonances in nickel oxide while the induced dynamics is recorded by femtosecond magneto-optical probing. We observe distinct spin-mediated optical nonlinearities, including oscillations at the second harmonic of the 1 THz magnon mode. The latter originate from coherent dynamics of the longitudinal component of the antiferromagnetic order parameter, which are probed by magneto-optical effects of second order in the spin deflection. These observations allow us to dynamically disentangle electronic from lattice-related contributions to magnetic linear birefringence and dichroism—information so far only accessible by ultrafast THz spin control. The nonlinearities discussed here foreshadow physics that will become essential in future subcycle spin switching.

  19. Scattering bottleneck for spin dynamics in metallic helical antiferromagnetic dysprosium

    Science.gov (United States)

    Langner, M. C.; Roy, S.; Kemper, A. F.; Chuang, Y.-D.; Mishra, S. K.; Versteeg, R. B.; Zhu, Y.; Hertlein, M. P.; Glover, T. E.; Dumesnil, K.; Schoenlein, R. W.

    2015-11-01

    Ultrafast studies of magnetization dynamics have revealed fundamental processes that govern spin dynamics, and the emergence of time-resolved x-ray techniques has extended these studies to long-range spin structures that result from interactions with competing symmetries. By combining time-resolved resonant x-ray scattering and ultrafast magneto-optical Kerr studies, we show that the dynamics of the core spins in the helical magnetic structure occur on much longer time scales than the excitation of conduction electrons in the lanthanide metal Dy. The observed spin behavior differs markedly from that observed in the ferromagnetic phase of other lanthanide metals or transition metals and is strongly dependent on temperature and excitation fluence. This unique behavior results from coupling of the real-space helical spin structure to the shape of the conduction electron Fermi surface in momentum space, which creates a bottleneck in spin scattering events that transfer the valence excitation to the core spins. The dependence of the dynamics on the intersite interactions renders the helical ordering much more robust to perturbations than simple ferromagnetic or antiferromagnetic ordering, where dynamics are driven primarily by on-site interactions.

  20. Quantum Spin Liquids in Frustrated Spin-1 Diamond Antiferromagnets

    Science.gov (United States)

    Buessen, Finn Lasse; Hering, Max; Reuther, Johannes; Trebst, Simon

    2018-01-01

    Motivated by the recent synthesis of the spin-1 A -site spinel NiRh2 O4 , we investigate the classical to quantum crossover of a frustrated J1-J2 Heisenberg model on the diamond lattice upon varying the spin length S . Applying a recently developed pseudospin functional renormalization group approach for arbitrary spin-S magnets, we find that systems with S ≥3 /2 reside in the classical regime, where the low-temperature physics is dominated by the formation of coplanar spirals and a thermal (order-by-disorder) transition. For smaller local moments S =1 or S =1 /2 , we find that the system evades a thermal ordering transition and forms a quantum spiral spin liquid where the fluctuations are restricted to characteristic momentum-space surfaces. For the tetragonal phase of NiRh2 O4 , a modified J1-J2--J2⊥ exchange model is found to favor a conventionally ordered Néel state (for arbitrary spin S ), even in the presence of a strong local single-ion spin anisotropy, and it requires additional sources of frustration to explain the experimentally observed absence of a thermal ordering transition.

  1. Self-consistent hole motion and spin excitations in a quantum antiferromagnet

    International Nuclear Information System (INIS)

    Su, Z.B.; Yu, L.; Li, Y.M.; Lai, W.Y.

    1989-12-01

    A new quantum Bogoliubov-de Gennes (BdeG) formalism is developed to study the self-consistent motion of holes and spin excitations in a quantum antiferromagnet within the generalized t-J model. On the one hand, the effects of local distortion of spin configurations and the renormalization of the hole motion due to virtual excitations of the distorted spin background are treated on an equal footing to obtain the hole wave function and its spectrum, as well as the effective mass for a propagating hole. On the other hand, the change of the spin excitation spectrum and the spin correlations due to the presence of dynamical holes are studied within the same adiabatic approximation. The stability of the hole states with respect to such changes justifies the self-consistency of the proposed formalism. (author). 25 refs, 6 figs, 1 tab

  2. Spin stiffness of frustrated Heisenberg antiferromagnets: Finite size scaling

    International Nuclear Information System (INIS)

    Feiguin, A.E.; Gazza, C.J.; Trumper, A.E.

    1995-07-01

    We calculate the spin stiffness of the S = 1/2 frustrated Heisenberg antiferromagnet on finite square lattices by means of the Schwinger - boson approach. COmparison with recent exact numerical results reveals that the observed lack of scaling with lattice size for intermediate to large frustration cannot be taken as an indication of absence of Neel order. This lack of scaling is already apparent for small frustration and is a finite lattice effect. Our results also indicate that the expected behaviour is regained for larger lattices than those considered in numerical studies. (author). 18 refs, 2 figs

  3. Properties of Haldane Excitations and Multiparticle States in the Antiferromagnetic Spin-1 Chain Compound CsNiCl3

    International Nuclear Information System (INIS)

    Kenzelmann, M.; Cowley, R.A.; Buyers, W.J.L.; Tun, Z.; Coldea, Radu; Enderle, M.

    2002-01-01

    We report inelastic time-of-flight and triple-axis neutron scattering measurements of the excitation spectrum of the coupled antiferromagnetic spin-1 Heisenberg chain system CsNiCl 3 . Measurements over a wide range of wave-vector transfers along the chain confirm that above T N CsNiCl 3 is in a quantum-disordered phase with an energy gap in the excitation spectrum. The spin correlations fall off exponentially with increasing distance with a correlation length ζ = 4.0(2) sites at T = 6.2K. This is shorter than the correlation length for an antiferromagnetic spin-1 Heisenberg chain at this temperature, suggesting that the correlations perpendicular to the chain direction and associated with the interchain coupling lower the single-chain correlation length. A multiparticle continuum is observed in the quantum-disordered phase in the region in reciprocal space where antiferromagnetic fluctuations are strongest, extending in energy up to twice the maximum of the dispersion of the well-defined triplet excitations. We show that the continuum satisfies the Hohenberg-Brinkman sum rule. The dependence of the multiparticle continuum on the chain wave vector resembles that of the two-spinon continuum in antiferromagnetic spin-1/2 Heisenberg chains. This suggests the presence of spin-1/2 degrees of freedom in CsNiCl 3 for T ∼< 12 K, possibly caused by multiply frustrated interchain interactions.

  4. Exact Solutions for Correlations in the Kagomé Ising Antiferromagnet

    Science.gov (United States)

    Barry, J. H.; Khatun, M.

    The kagomé Ising antiferromagnet is highly frustrated with its pair correlation decaying exponentially at large distance for all temperatures including absolute zero. Hence, the spin system does not support long-range orderings and is devoid of any phase transition. One proves, via local star-triangle and decoration-decimation transformations, that correlations in the kagomé Ising antiferromagnet at arbitrary temperatures can be represented as linear combinations of correlations in the honeycomb Ising ferromagnet at high temperatures (disordered region). Existent knowledge of all honeycomb Ising correlations upon a select (spatially compact) 10-site cluster is thus sufficient to determine all present kagomé Ising correlations upon an associated 9-site cluster. Examples of resulting exact solutions for pair and multisite correlations in the kagomé Ising antiferromagnet are presented at all temperatures. Applications include joint configuration probabilities, thermodynamic response functions such as the specific heat and the initial perpendicular susceptibility, and the inelastic neutron scattering function.

  5. Evolution of spin excitations in a gapped antiferromagnet from the quantum to the high-temperature limit

    DEFF Research Database (Denmark)

    Kenzelmann, M.; Cowley, R.A.; Buyers, W.J.L.

    2002-01-01

    We have mapped from the quantum to the classical limit the spin excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain system CsNiCl3 in its paramagnetic phase from T=5 to 200 K. Neutron scattering shows that the excitations are resonant and dispersive up to at least T=70 Ksimilar...... or equal to2.7J, but broaden considerably with increasing temperature. The dispersion flattens out with increasing temperature as the resonance energy Delta at the antiferromagnetic wave vector increases and the maximum in the dispersion decreases. The correlation length xi between T=12 and 50 K...

  6. Superconductivity and antiferromagnetism in cuprates and pnictides: Evidence of the role of Coulomb correlation

    International Nuclear Information System (INIS)

    Fan, J.D.; Malozovsky, Y.M.

    2013-01-01

    Highlights: • In a layered 2D cuprates the long-range order antiferromagnetism is driven mainly by the Van Hove singularity. • The long-range antiferromagnetism quickly disappear with doping away from the Van Hove singularity. • For pnictides the antiferromagnetism exists as a result of the nesting condition. • Since the doping steadily changes the nesting conditions, the antiferromagnetism and superconductivity may coexist. -- Abstract: We consider the Hubbard model in terms of the perturbative diagrammatic approach (UN F ⩽1) where the interaction between two electrons with antiparallel spins in the lowest order of perturbation is described by the short-range repulsive contact (on-site) interaction (U>0). We argue that in layered 2D cuprates the long-range order antiferromagnetism is driven mainly by the Van Hove singularity, whereas in the case of pnictides the antiferromagnetism exists as a result of the nesting condition. We show that when the interaction is quite strong (UN F ≈1) in the case of the Van Hove singularity the electron system undergoes the antiferromagnetic phase transition with the log-range order parameter and large insulating gap. The long-range antiferromagnetism quickly disappear, as shown, with the doping away from the Van Hove singularity, but the antiferromagnetic short-range correlation persists (UN F < 1) due to Coulomb repulsive interaction which is the mechanism for superconductivity in cuprates. We argue that in the case of pnictides the antiferromagnetism appears when the nesting conditions for the Fermi surface are met. Since the doping steadily changes the nesting conditions, the antiferromagnetism and superconductivity may coexist as has been observed in pnictides. We show that the proximity of the antiferromagnetism and superconductivity implies the repulsive interaction between electrons, which turns into attractive between quasiparticles as shown by the authors in the article published on the same issue as this one

  7. Spin freezing in the geometrically frustrated pyrochlore antiferromagnet Tb2Mo2O7

    DEFF Research Database (Denmark)

    Gaulin, B.D.; Reimers, J.N.; Mason, T.E.

    1992-01-01

    The magnetic metal ions in the cubic pyrochlore Tb2Mo2O7 form an infinite three-dimensional network of corner-sharing tetrahedra with a very high potential for frustration in the presence of antiferromagnetism. We have performed neutron scattering measurements which show short-range spatial...... correlations that develop continuously with decreasing temperature, while the characteristic time scale for the fluctuating moments decreases dramatically below T(f) is similar to 25 K. Therefore, this pure material, which possesses frustration that is purely geometrical in origin, displays a spin-glass state...

  8. Spin waves treatment of the antiferromagnetic ground state of two Ising-like systems

    Directory of Open Access Journals (Sweden)

    Adegoke Kunle

    2014-01-01

    Full Text Available Using Anderson's spin wave theory, we derive expressions for the ground state energy of two Ising-like systems. Antiferromagnetic long range order is predicted for one of the systems.

  9. Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

    KAUST Repository

    Ghosh, Sumit

    2017-01-24

    We investigate spin transport in two-dimensional ferromagnetic (FTI) and antiferromagnetic (AFTI) topological insulators. In the presence of an in-plane magnetization AFTI supports zero energy modes, which enables topologically protected edge conduction at low energy. We address the nature of current-driven spin torque in these structures and study the impact of spin-independent disorder. Interestingly, upon strong disorder the spin torque develops an antidamping component (i.e., even upon magnetization reversal) along the edges, which could enable current-driven manipulation of the antiferromagnetic order parameter. This antidamping torque decreases when increasing the system size and when the system enters the trivial insulator regime.

  10. Odd number of coupled antiferromagnetic anisotropic Heisenberg chains: Spin wave theory

    International Nuclear Information System (INIS)

    Benyoussef, A.

    1996-10-01

    The effect of the chain and perpendicular anisotropies on the energy gap for odd number of coupled quantum spin-1/2 antiferromagnetic anisotropic Heisenberg chains is investigated using a spin wave theory. The energy gap opens above a critical anisotropic value. The known results of the isotropic case have been obtained. (author). 11 refs, 4 figs

  11. Persistent nonequilibrium dynamics of the thermal energies in the spin and phonon systems of an antiferromagnet

    Directory of Open Access Journals (Sweden)

    A. von Reppert

    2016-09-01

    Full Text Available We present a temperature and fluence dependent Ultrafast X-Ray Diffraction study of a laser-heated antiferromagnetic dysprosium thin film. The loss of antiferromagnetic order is evidenced by a pronounced lattice contraction. We devise a method to determine the energy flow between the phonon and spin system from calibrated Bragg peak positions in thermal equilibrium. Reestablishing the magnetic order is much slower than the cooling of the lattice, especially around the Néel temperature. Despite the pronounced magnetostriction, the transfer of energy from the spin system to the phonons in Dy is slow after the spin-order is lost.

  12. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    2 states. A coherent spin-s state. (CSS) θ φ can then be thought of as having no quantum correlations as the constituent. 2s elementary spins point in the same direction ˆn(θ φ) which is the mean spin direction. 2. State classification and squeezing. In order to discuss squeezing, we begin with the squeezing condition itself.

  13. Frustrated spin-1/2 Ising antiferromagnet on a square lattice in a transverse field

    Science.gov (United States)

    Bobák, A.; Jurčišinová, E.; Jurčišin, M.; Žukovič, M.

    2018-02-01

    We investigate the phase transitions and tricritical behaviors of the frustrated Ising antiferromagnet with first- (J1<0 ) and second- (J2<0 ) nearest-neighbor interactions in a transverse field Ω on the square lattice using an effective-field theory with correlations based on a single-spin approximation. We have proposed a functional for the free energy to obtain the phase diagram in the T -R (R =J2/|J1| ) or T -Ω planes. It is shown that due to the transverse field the phase transition between ordered and disordered phases changes in the tricritical point (TCP) from the second order to the first order. The longitudinal and transverse magnetizations are also studied for selected values of R and Ω . In particular, the variation of TCP at the ground state in the three-dimensional space is constructed. For some special cases, values of the critical temperature and the critical transverse field have been determined analytically.

  14. Real-space imaging of non-collinear antiferromagnetic order with a single-spin magnetometer

    Science.gov (United States)

    Gross, I.; Akhtar, W.; Garcia, V.; Martínez, L. J.; Chouaieb, S.; Garcia, K.; Carrétéro, C.; Barthélémy, A.; Appel, P.; Maletinsky, P.; Kim, J.-V.; Chauleau, J. Y.; Jaouen, N.; Viret, M.; Bibes, M.; Fusil, S.; Jacques, V.

    2017-09-01

    Although ferromagnets have many applications, their large magnetization and the resulting energy cost for switching magnetic moments bring into question their suitability for reliable low-power spintronic devices. Non-collinear antiferromagnetic systems do not suffer from this problem, and often have extra functionalities: non-collinear spin order may break space-inversion symmetry and thus allow electric-field control of magnetism, or may produce emergent spin-orbit effects that enable efficient spin-charge interconversion. To harness these traits for next-generation spintronics, the nanoscale control and imaging capabilities that are now routine for ferromagnets must be developed for antiferromagnetic systems. Here, using a non-invasive, scanning single-spin magnetometer based on a nitrogen-vacancy defect in diamond, we demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature. We image the spin cycloid of a multiferroic bismuth ferrite (BiFeO3) thin film and extract a period of about 70 nanometres, consistent with values determined by macroscopic diffraction. In addition, we take advantage of the magnetoelectric coupling present in BiFeO3 to manipulate the cycloid propagation direction by an electric field. Besides highlighting the potential of nitrogen-vacancy magnetometry for imaging complex antiferromagnetic orders at the nanoscale, these results demonstrate how BiFeO3 can be used in the design of reconfigurable nanoscale spin textures.

  15. Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si

    Science.gov (United States)

    Lou, Paul C.; Kumar, Sandeep

    2018-04-01

    Spin current experiences minimal dephasing and scattering in Si due to small spin-orbit coupling and spin-lattice interactions is the primary source of spin relaxation. We hypothesize that if the specimen dimension is of the same order as the spin diffusion length then spin polarization will lead to non-equilibrium spin accumulation and emergent phase transition. In n-Si, spin diffusion length has been reported up to 6 μm. The spin accumulation in Si will modify the thermal transport behavior of Si, which can be detected with thermal characterization. In this study, we report observation of spin-Hall effect and emergent antiferromagnetic phase transition behavior using magneto-electro-thermal transport characterization. The freestanding Pd (1 nm)/Ni80Fe20 (75 nm)/MgO (1 nm)/n-Si (2 μm) thin film specimen exhibits a magnetic field dependent thermal transport and spin-Hall magnetoresistance behavior attributed to Rashba effect. An emergent phase transition is discovered using self-heating 3ω method, which shows a diverging behavior at 270 K as a function of temperature similar to a second order phase transition. We propose that spin-Hall effect leads to the spin accumulation and resulting emergent antiferromagnetic phase transition. We propose that the length scale for Rashba effect can be equal to the spin diffusion length and two-dimensional electron gas is not essential for it. The emergent antiferromagnetic phase transition is attributed to the site inversion asymmetry in diamond cubic Si lattice.

  16. Spin polaron in two-dimensional antiferromagnetics - from local singlet to compound quasi-particle

    CERN Document Server

    Barabanov, A F; Belemuk, A M

    2002-01-01

    The basic theoretical concepts, related to the spin polaron scenario for the charge excitations in the two-dimensional antiferromagnetics, are presented. The distinctive peculiarity of the developed approach consists in consideration of the local polaron as the zero approximation for the quasi-particles. On the following stage this excitation is coated into the antiferromagnetic spin waves and the radius intermediate polaron is formed. The method makes it possible to continuously describe the transition from the zero temperatures to the finite ones and to consider the wide doping range. The above approach explains basic results of the ARPES-experiments in the CuO sub 2 plane

  17. Magnetization plateaus in the spin-1/2 antiferromagnetic Heisenberg model on a kagome-strip chain

    Science.gov (United States)

    Morita, Katsuhiro; Sugimoto, Takanori; Sota, Shigetoshi; Tohyama, Takami

    2018-01-01

    The spin-1/2 Heisenberg model on a kagome lattice is a typical frustrated quantum spin system. The basic structure of a kagome lattice is also present in the kagome-strip lattice in one dimension, where a similar type of frustration is expected. We thus study the magnetization plateaus of the spin-1/2 Heisenberg model on a kagome-strip chain with three-independent antiferromagnetic exchange interactions using the density-matrix renormalization-group method. In a certain range of exchange parameters, we find twelve kinds of magnetization plateaus, nine of which have magnetic structures breaking translational and/or reflection symmetry spontaneously. The structures are classified by an array of five-site unit cells with specific bond-spin correlations. In a case with a nontrivial plateau, namely a 3/10 plateau, we find long-period magnetic structure with a period of four unit cells.

  18. Antiferromagnetism in the Hubbard model using a cluster slave-spin method

    Science.gov (United States)

    Lee, Wei-Cheng; Lee, Ting-Kuo

    2017-09-01

    The cluster slave-spin method is introduced to systematically investigate the solutions of the Hubbard model including the symmetry-broken phases. In this method, the electron operator is factorized into a fermionic spinon describing the physical spin and a slave-spin describing the charge fluctuations. Following the U (1 ) formalism derived by Yu and Si [Phys. Rev. B 86, 085104 (2012), 10.1103/PhysRevB.86.085104], it is shown that the self-consistent equations to explore various symmetry-broken density wave states can be constructed in general with a cluster of multiple slave-spin sites. We employ this method to study the antiferromagnetic (AFM) state in the single band Hubbard model with the two- and four-site clusters of slave spins. While the Hubbard gap, the charge gap due to the doubly occupied states, scales with the Hubbard interaction U as expected, the AFM gap Δ , the gap in the spinon dispersion in the AFM state, exhibits a crossover from the weak- to strong-coupling behaviors as U increases. Our cluster slave-spin method reproduces not only the traditional mean-field behavior of Δ ˜U in the weak-coupling limit, but also the behavior of Δ ˜t2/U predicted by the superexchange mechanism in the strong-coupling limit. In addition, the holon-doublon correlator as functions of U and doping x is also computed, which exhibits a strong tendency toward the holon-doublon binding in the strong coupling regime. We further show that the quasiparticle weight obtained by the cluster slave-spin method is in a good agreement with the generalized Gutzwiller approximation in both AFM and paramagnetic states, and the results can be improved beyond the generalized Gutzwiller approximation as the cluster is enlarged from a single site to four sites. Our results demonstrate that the cluster slave-spin method can be a powerful tool to systematically investigate the strongly correlated system.

  19. Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets

    KAUST Repository

    Železný, J.

    2017-01-10

    One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J. Železný, Phys. Rev. Lett. 113, 157201 (2014)]PRLTAO0031-900710.1103/PhysRevLett.113.157201, the electrical switching of magnetic moments in an antiferromagnet was demonstrated [P. Wadley, Science 351, 587 (2016)]SCIEAS0036-807510.1126/science.aab1031. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a nonequilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analysis of the symmetry of the spin-orbit torque in locally and globally noncentrosymmetric crystals. We study when the symmetry allows for a nonzero torque, when is the torque effective, and its dependence on the applied current direction and orientation of magnetic moments. For comparison, we consider both antiferromagnetic and ferromagnetic orders. In two representative model crystals we perform microscopic calculations of the spin-orbit torque to illustrate its symmetry properties and to highlight conditions under which the spin-orbit torque can be efficient for manipulating antiferromagnetic moments.

  20. Nonlocally sensing the magnetic states of nanoscale antiferromagnets with an atomic spin sensor.

    Science.gov (United States)

    Yan, Shichao; Malavolti, Luigi; Burgess, Jacob A J; Droghetti, Andrea; Rubio, Angel; Loth, Sebastian

    2017-05-01

    The ability to sense the magnetic state of individual magnetic nano-objects is a key capability for powerful applications ranging from readout of ultradense magnetic memory to the measurement of spins in complex structures with nanometer precision. Magnetic nano-objects require extremely sensitive sensors and detection methods. We create an atomic spin sensor consisting of three Fe atoms and show that it can detect nanoscale antiferromagnets through minute, surface-mediated magnetic interaction. Coupling, even to an object with no net spin and having vanishing dipolar stray field, modifies the transition matrix element between two spin states of the Fe atom-based spin sensor that changes the sensor's spin relaxation time. The sensor can detect nanoscale antiferromagnets at up to a 3-nm distance and achieves an energy resolution of 10 μeV, surpassing the thermal limit of conventional scanning probe spectroscopy. This scheme permits simultaneous sensing of multiple antiferromagnets with a single-spin sensor integrated onto the surface.

  1. Superconductivity, Antiferromagnetism, and Neutron Scattering

    OpenAIRE

    Tranquada, John M.; Xu, Guangyong; Zaliznyak, Igor A.

    2013-01-01

    High-temperature superconductivity in both the copper-oxide and the iron-pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements...

  2. Spin configuration in a frustrated ferromagnetic/antiferromagnetic thin-film system

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, T K [Faculty of Science, Gakushuin University, 171-8588 Mejiro, Tokyo (Japan); MartInez, E [Fachbereich Physik, Universitaet Osnabrueck, D-49069 Osnabrueck (Germany); Vega, A [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47011 Valladolid (Spain); Robles, R [Department of Physics, Uppsala University, SE-75121 (Sweden); Stoeffler, D [Institut de Physique et Chimie des Materiaux de Strasbourg (UMR C7504 CNRS-ULP), Strasbourg (France); Parga, A L Vazquez de [Departamento de Fisica de la Materia Condensada, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Mizoguchi, T [Faculty of Science, Gakushuin University, 171-8588 Mejiro, Tokyo (Japan); Kempen, H van [Institute for Molecules and Materials, Radboud University, Toernooiveld 1, 6525 ED Nijmegen (Netherlands)

    2007-06-13

    We have studied the magnetic configuration in ultrathin antiferromagnetic Mn films grown around monoatomic steps on an Fe(001) surface by spin-polarized scanning tunnelling microscopy/spectroscopy and ab initio-parameterized self-consistent real-space tight-binding calculations in which the spin quantization axis is independent for each site, thus allowing noncollinear magnetism. Mn grown on Fe(001) presents a layered antiferromagnetic structure. In the regions where the Mn films overgrows Fe steps the magnetization of the surface layer is reversed across the steps. Around these defects a frustration of the antiferromagnetic order occurs. Due to the weakened magnetic coupling at the central Mn layers, the amount of frustration is smaller than in Cr, and the width of the wall induced by the step does not change with the thickness, at least for coverages up to seven monolayers.

  3. Ferromagnetic and Antiferromagnetic Coupling of Spin Molecular Interfaces with High Thermal Stability.

    Science.gov (United States)

    Avvisati, Giulia; Cardoso, Claudia; Varsano, Daniele; Ferretti, Andrea; Gargiani, Pierluigi; Betti, Maria Grazia

    2018-03-26

    We report an advanced organic spin-interface architecture with magnetic remanence at room temperature, constituted by metal phthalocyanine molecules magnetically coupled with Co layer(s), mediated by graphene. Fe- and Cu-phthalocyanines assembled on graphene/Co have identical structural configurations, but FePc couples antiferromagnetically with Co up to room temperature, while CuPc couples ferromagnetically with weaker coupling and thermal stability, as deduced by element-selective X-ray magnetic circular dichroic signals. The robust antiferromagnetic coupling is stabilized by a superexchange interaction, driven by the out-of-plane molecular orbitals responsible of the magnetic ground state and electronically decoupled from the underlying metal via the graphene layer, as confirmed by ab initio theoretical predictions. These archetypal spin interfaces can be prototypes to demonstrate how antiferromagnetic and/or ferromagnetic coupling can be optimized by selecting the molecular orbital symmetry.

  4. Microscopic theory of the nearest-neighbor valence bond sector of the spin-1/2 kagome antiferromagnet

    Science.gov (United States)

    Ralko, Arnaud; Mila, Frédéric; Rousochatzakis, Ioannis

    2018-03-01

    The spin-1/2 Heisenberg model on the kagome lattice, which is closely realized in layered Mott insulators such as ZnCu3(OH) 6Cl2 , is one of the oldest and most enigmatic spin-1/2 lattice models. While the numerical evidence has accumulated in favor of a quantum spin liquid, the debate is still open as to whether it is a Z2 spin liquid with very short-range correlations (some kind of resonating valence bond spin liquid), or an algebraic spin liquid with power-law correlations. To address this issue, we have pushed the program started by Rokhsar and Kivelson in their derivation of the effective quantum dimer model description of Heisenberg models to unprecedented accuracy for the spin-1/2 kagome, by including all the most important virtual singlet contributions on top of the orthogonalization of the nearest-neighbor valence bond singlet basis. Quite remarkably, the resulting picture is a competition between a Z2 spin liquid and a diamond valence bond crystal with a 12-site unit cell, as in the density-matrix renormalization group simulations of Yan et al. Furthermore, we found that, on cylinders of finite diameter d , there is a transition between the Z2 spin liquid at small d and the diamond valence bond crystal at large d , the prediction of the present microscopic description for the two-dimensional lattice. These results show that, if the ground state of the spin-1/2 kagome antiferromagnet can be described by nearest-neighbor singlet dimers, it is a diamond valence bond crystal, and, a contrario, that, if the system is a quantum spin liquid, it has to involve long-range singlets, consistent with the algebraic spin liquid scenario.

  5. Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling.

    Science.gov (United States)

    Coffey, David; Diez-Ferrer, José Luis; Serrate, David; Ciria, Miguel; de la Fuente, César; Arnaudas, José Ignacio

    2015-09-03

    High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.

  6. The Multisite Antiferromagnetic Ising Spin Model and Universality of Feigenbaum Constants

    OpenAIRE

    Ananikian, N. S.; Lusiniants, R. R.; Oganessyan, K. A.

    1994-01-01

    The Feigenbaum constants $\\alpha$ and $\\delta$ for the three-site antiferromagnetic Ising spin model on Husimi tree are calculated. It is shown that the numerical values of these constants for this real physical system coincide with the famous universal Feigenbaum constants with high accuracy. The quantitative description from ordering to chaos is also obtained.

  7. Spin wave analysis to the spatially-anisotropic Heisenberg antiferromagnet on triangular lattice

    OpenAIRE

    Trumper, Adolfo E.

    1998-01-01

    We study the phase diagram at T=0 of the antiferromagnetic Heisenberg model on the triangular lattice with spatially-anisotropic interactions. For values of the anisotropy very close to J_alpha/J_beta=0.50, conventional spin wave theory predicts that quantum fluctuations melt the classical structures, for S=1/2. For the regime J_beta

  8. Spin-transfer torques in antiferromagnetic textures: efficiency and quantification method

    Czech Academy of Sciences Publication Activity Database

    Yamane, Y.; Ieda, J.; Sinova, Jairo

    2016-01-01

    Roč. 94, č. 5 (2016), 1-8, č. článku 054409. ISSN 2469-9950 R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : spin-transfer torques * antiferromagnets Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.836, year: 2016

  9. Low-frequency spin dynamics and NMR spin-lattice relaxation in antiferromagnetic rings

    Science.gov (United States)

    Itou, T.; Sagane, T.; Oyamada, A.; Maegawa, S.; Igarashi, S.; Yukawa, Y.

    2011-01-01

    We develop a general theory of the spin dynamics of Heisenberg antiferromagnetic rings (HAFRs) that explains the mechanism of NMR spin-lattice relaxation at low temperatures. In HAFRs, the imaginary parts of the q-summed dynamic spin susceptibilities parallel and perpendicular to an applied static field, χsum∥″(ω) and χsum⊥″(ω), are composed of the sum of many slightly broadened δ-functional modes at many frequencies. The NMR relaxation is caused by the quasielastic mode in χsum∥″(ω) at around zero frequency. This quasielastic mode is characterized by two physical quantities, intensity P0∥ and frequency width Γ0∥. Although P0∥ has to date been assumed to be identical to the uniform static susceptibility, we point out that the two quantities are not identical. Without making this unreliable assumption for P0∥, we demonstrate experimentally how P0∥ and Γ0∥ behave, by analyzing the NMR relaxation rates of two different nuclei, H1 and C13, in a real HAFR. This analysis is more rigorous and thus can be used to estimate Γ0∥ and P0∥ more precisely than previously possible. We find that the temperature dependence of P0∥ exhibits activation-type behavior reflecting the first excitation gap. We also find that Γ0∥ decreases monotonically on cooling but saturates to a nonzero value at zero temperature. This strongly suggests that Γ0∥ is dominated not only by the electron-phonon interactions but also by internanomagnet dipole interactions, which have been neglected to date.

  10. Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

    2017-08-15

    Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

  11. Spin liquid in a single crystal of the frustrated diamond lattice antiferromagnet CoAl2O4

    DEFF Research Database (Denmark)

    Zaharko, O.; Christensen, Niels Bech; Cervellino, A.

    2011-01-01

    We study the evidence for spin liquid in the frustrated diamond lattice antiferromagnet CoAl2O4 by means of single-crystal neutron scattering in zero and applied magnetic fields. The magnetically ordered phase appearing below T-N = 8 K remains nonconventional down to 1.5 K. The magnetic Bragg peaks...... at the q = 0 positions are broad and their line shapes have strong Lorentzian contributions. Additionally, the peaks are connected by weak diffuse streaks oriented along the directions. The observed short-range magnetic correlations are explained within the spiral spin-liquid model. The specific...... shape of the energy landscape of the system, with an extremely flat energy minimum around q = 0 and many low-lying excited spiral states with q = , results in thermal population of this manifold at finite temperatures. The agreement between the experimental results and the spiral spin-liquid model...

  12. Spin-lattice effects in selected antiferromagnetic materials

    Czech Academy of Sciences Publication Activity Database

    Zherlitsyn, S.; Yasin, S.; Wosnitza, J.; Zvyagin, A.A.; Andreev, Alexander V.; Tsurkan, V.

    2014-01-01

    Roč. 40, č. 2 (2014), s. 123-133 ISSN 1063-777X R&D Projects: GA ČR GAP204/12/0150 Grant - others:AVČR(CZ) M100101203 Keywords : low-dimensional spin systems * frustrated chromium spinels * spin-strain interaction * uranium-based compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.786, year: 2014

  13. Correlated electric-field induced reversal of antiferromagnetic order and surface magnetization in magnetoelectric Cr2O3

    Science.gov (United States)

    Wang, Junlei; Singh, Uday; Binek, Christian

    The electric-field-induced Faraday effect in magnetoelectrics comprises a superimposition of linear electric field responses with temperature dependencies of the linear magnetoelectric susceptibility and the antiferromagnetic order parameter. The tunability of the relative strength between the two contributions leads to a table-top set-up allowing to measure voltage-controlled selection and temperature dependence of the antiferromagnetic order parameter. Simultaneous measurement of the polar Kerr effect and the electric-field-induced Faraday effect is utilized to investigate correlated formation and switching of the surface magnetization and bulk antiferromagnetic order in Cr2O3 The correlated reversal of surface or boundary magnetization in response to voltage-controlled reversal of the bulk antiferromagnetic order parameter is of key importance for applications in spintronic devices such as the magnetoelectric MRAM. The Faraday rotation per applied voltage is independent of the sample thickness making the method scalable and versatile for thin film investigations. Scalability, compactness, and simplicity of the data analysis combined with low photon flux requirements make the Faraday approach advantageous for the investigation of the otherwise difficult to access voltage-controlled switching of antiferromagnetic domain states in magnetoelectric thin films. Acknowledgment: This project was supported by SRC through CNFD, an SRC-NRI Center, by C-SPIN, part of STARnet, and by the NSF through MRSEC DMR-0820521.

  14. Itinerant spin dynamics in iron-based superconductors and cerium-based heavy-fermion antiferromagnets

    International Nuclear Information System (INIS)

    Friemel, Gerd

    2014-01-01

    This thesis contains a comprehensive study of the spin excitations by inelastic neutron scattering (INS) in two different correlated electron systems: the alkali-metal iron selenide superconductors (FeSe122) A x Fe 2-y Se 2 (A=K, Rb, Cs) and the heavy-fermion antiferromagnet CeB6. Both systems exhibit intense modes in their spin-fluctuation spectrum below their respective transition temperatures that can be derived from the spin dynamics of the itinerant quasiparticles. However, the implications of these observations, presented here, are different for each particular compound. The A x Fe 2-y Se 2 superconductors, with a uniform T c of 32 K, belong to a qualitative new family of superconductors. They possess a distinctly different Fermi surface compared to the iron-arsenide-based analogues XFe 2 As 2 (X=Ca, Sr, Ba). Instead of the central hole pockets at Γ and the electron pockets at X((1)/(2) 0), which are nested by the Q AFM = ((1)/(2) 0) vector, there exist only large electron pockets at the X point. Therefore, the magnetic instability along Q AFM that presumably provides the pairing glue for the superconductivity in the shape of spin fluctuations is absent in the FeSe122. The search for spin fluctuations by INS was motivated by a theoretical analysis that predicted their presence at an incommensurate wave vector near Q = (0.5 δ), δ = 0.3125 which results from a quasinesting by Q between the flat parts of the electron pockets. Two samples, namely Rb 0.8 Fe 1.6 Se 2 and K 0.77 Fe 1.85 Se 2 , were prepared and both showed a sizable anisotropic magnetic response at Q sf = ((1)/(2) (1)/(4)) in the normal state. Furthermore, upon entering the superconducting (SC) state a strong excitation appears at ℎω res = 14 meV in the spectrum at Q sf , which is referred to as magnetic resonant mode. This mode is interpreted as a bound spin-1 exciton below the SC charge gap. Its presence implies an unconventional order parameter, which changes the sign between the electron

  15. Itinerant spin dynamics in iron-based superconductors and cerium-based heavy-fermion antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Friemel, Gerd

    2014-05-26

    This thesis contains a comprehensive study of the spin excitations by inelastic neutron scattering (INS) in two different correlated electron systems: the alkali-metal iron selenide superconductors (FeSe122) A{sub x}Fe{sub 2-y}Se{sub 2} (A=K, Rb, Cs) and the heavy-fermion antiferromagnet CeB6. Both systems exhibit intense modes in their spin-fluctuation spectrum below their respective transition temperatures that can be derived from the spin dynamics of the itinerant quasiparticles. However, the implications of these observations, presented here, are different for each particular compound. The A{sub x}Fe{sub 2-y}Se{sub 2} superconductors, with a uniform T{sub c} of 32 K, belong to a qualitative new family of superconductors. They possess a distinctly different Fermi surface compared to the iron-arsenide-based analogues XFe{sub 2}As{sub 2} (X=Ca, Sr, Ba). Instead of the central hole pockets at Γ and the electron pockets at X((1)/(2) 0), which are nested by the Q{sub AFM} = ((1)/(2) 0) vector, there exist only large electron pockets at the X point. Therefore, the magnetic instability along Q{sub AFM} that presumably provides the pairing glue for the superconductivity in the shape of spin fluctuations is absent in the FeSe122. The search for spin fluctuations by INS was motivated by a theoretical analysis that predicted their presence at an incommensurate wave vector near Q = (0.5 δ), δ = 0.3125 which results from a quasinesting by Q between the flat parts of the electron pockets. Two samples, namely Rb{sub 0.8}Fe{sub 1.6}Se{sub 2} and K{sub 0.77}Fe{sub 1.85}Se{sub 2}, were prepared and both showed a sizable anisotropic magnetic response at Q{sub sf} = ((1)/(2) (1)/(4)) in the normal state. Furthermore, upon entering the superconducting (SC) state a strong excitation appears at ℎω{sub res} = 14 meV in the spectrum at Q{sub sf}, which is referred to as magnetic resonant mode. This mode is interpreted as a bound spin-1 exciton below the SC charge gap. Its presence

  16. Chiral Spin Liquid on a Kagome Antiferromagnet Induced by the Dzyaloshinskii-Moriya Interaction

    Science.gov (United States)

    Messio, Laura; Bieri, Samuel; Lhuillier, Claire; Bernu, Bernard

    2017-06-01

    The quantum spin liquid material herbertsmithite is described by an antiferromagnetic Heisenberg model on the kagome lattice with a non-negligible Dzyaloshinskii-Moriya interaction (DMI). A well-established phase transition to the q =0 long-range order occurs in this model when the DMI strength increases, but the precise nature of a small-DMI phase remains controversial. Here, we describe a new phase obtained from Schwinger-boson mean-field theory that is stable at small DMI, and which can explain the dispersionless spectrum seen in the inelastic neutron scattering experiment by Han et al. [Nature (London) 492, 406 (2012), 10.1038/nature11659]. It is a time-reversal symmetry breaking Z2 spin liquid, with the unique property of a small and constant spin gap in an extended region of the Brillouin zone. The phase diagram as a function of DMI and spin size is given, and dynamical spin structure factors are presented.

  17. Dynamical Negative Differential Resistance in Antiferromagnetically Coupled Few-Atom Spin Chains

    Science.gov (United States)

    Rolf-Pissarczyk, Steffen; Yan, Shichao; Malavolti, Luigi; Burgess, Jacob A. J.; McMurtrie, Gregory; Loth, Sebastian

    2017-11-01

    We present the appearance of negative differential resistance (NDR) in spin-dependent electron transport through a few-atom spin chain. A chain of three antiferromagnetically coupled Fe atoms (Fe trimer) was positioned on a Cu2 N /Cu (100 ) surface and contacted with the spin-polarized tip of a scanning tunneling microscope, thus coupling the Fe trimer to one nonmagnetic and one magnetic lead. Pronounced NDR appears at the low bias of 7 mV, where inelastic electron tunneling dynamically locks the atomic spin in a long-lived excited state. This causes a rapid increase of the magnetoresistance between the spin-polarized tip and Fe trimer and quenches elastic tunneling. By varying the coupling strength between the tip and Fe trimer, we find that in this transport regime the dynamic locking of the Fe trimer competes with magnetic exchange interaction, which statically forces the Fe trimer into its high-magnetoresistance state and removes the NDR.

  18. Inducing spin-dependent tunneling to probe magnetic correlations in optical lattices

    DEFF Research Database (Denmark)

    Pedersen, Kim Georg Lind; Andersen, Brian Møller; Bruun, Georg Morten

    2012-01-01

    We suggest a simple experimental method for probing antiferromagnetic spin correlations of two-component Fermi gases in optical lattices. The method relies on a spin selective Raman transition to excite atoms of one spin species to their first excited vibrational mode where the tunneling is large....... The resulting difference in the tunneling dynamics of the two spin species can then be exploited, to reveal the spin correlations by measuring the number of doubly occupied lattice sites at a later time. We perform quantum Monte Carlo simulations of the spin system and solve the optical lattice dynamics...... numerically to show how the timed probe can be used to identify antiferromagnetic spin correlations in optical lattices....

  19. Superconductivity, antiferromagnetism, and neutron scattering

    International Nuclear Information System (INIS)

    Tranquada, John M.; Xu, Guangyong; Zaliznyak, Igor A.

    2014-01-01

    High-temperature superconductivity in both the copper-oxide and the iron–pnictide/chalcogenide systems occurs in close proximity to antiferromagnetically ordered states. Neutron scattering has been an essential technique for characterizing the spin correlations in the antiferromagnetic phases and for demonstrating how the spin fluctuations persist in the superconductors. While the nature of the spin correlations in the superconductors remains controversial, the neutron scattering measurements of magnetic excitations over broad ranges of energy and momentum transfers provide important constraints on the theoretical options. We present an overview of the neutron scattering work on high-temperature superconductors and discuss some of the outstanding issues. - Highlights: • High-temperature superconductivity is closely associated with antiferromagnetism. • Antiferromagnetic spin fluctuations coexist with the superconductivity. • Neutron scattering is essential for characterising the full spectrum of spin excitations

  20. Quantum fluctuations in the competition among spin glass, antiferromagnetism and local pairing superconductivity

    International Nuclear Information System (INIS)

    Magalhaes, S.G.; Zimmer, F.M.; Kipper, C.J.; Calegari, E.J.

    2007-01-01

    The competition among spin glass (SG), antiferromagnetism (AF) and local pairing superconductivity (PAIR) is studied in a two-sublattice fermionic Ising SG model with a local BCS pairing interaction in the presence of a transverse magnetic field Γ. The spins in different sublattices interact with Gaussian random couplings with an antiferromagnetic mean. The problem is formulated in a Grassmann path integral formalism. The static ansatz and the replica symmetry are used to obtain the half-filling thermodynamic potential. The results are shown in phase diagrams that exhibit a complex transition line separating the PAIR phase from the others. This line is second order at high temperature which ends in a tricritical point. The presence of Γ affects deeply the transition lines

  1. su(1,2) Algebraic Structure of XYZ Antiferromagnetic Model in Linear Spin-Wave Frame

    International Nuclear Information System (INIS)

    Jin Shuo; Xie Binghao; Yu Zhaoxian; Hou Jingmin

    2008-01-01

    The XYZ antiferromagnetic model in linear spin-wave frame is shown explicitly to have an su(1,2) algebraic structure: the Hamiltonian can be written as a linear function of the su(1,2) algebra generators. Based on it, the energy eigenvalues are obtained by making use of the similar transformations, and the algebraic diagonalization method is investigated. Some numerical solutions are given, and the results indicate that only one group solution could be accepted in physics

  2. Spin-orbit coupling induced anisotropy effects in bimetallic antiferromagnets: A route towards antiferromagnetic spintronics

    Czech Academy of Sciences Publication Activity Database

    Shick, Alexander; Khmelevskyi, S.; Mryasov, O. N.; Wunderlich, J.; Jungwirth, Tomáš

    2010-01-01

    Roč. 81, č. 21 (2010), 212409/1-212409/4 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100912; GA ČR GA202/07/0456; GA AV ČR KAN400100652; GA ČR GEFON/06/E002 EU Projects: European Commission(XE) 215368 - SemiSpinNet; European Commission(XE) 214499 - NAMASTE Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : magnetic anisotropy * tunneling anisotropic magneto-resistance * exchange bias Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010 http://link.aps.org/doi/10.1103/PhysRevB.81.212409

  3. Neutron spin-echo study of the critical dynamics of spin-5/2 antiferromagnets in two and three dimensions

    Science.gov (United States)

    Tseng, K. F.; Keller, T.; Walters, A. C.; Birgeneau, R. J.; Keimer, B.

    2016-07-01

    We report a neutron spin-echo study of the critical dynamics in the S =5/2 antiferromagnets MnF2 and Rb2MnF4 with three-dimensional (3D) and two-dimensional (2D) spin systems, respectively, in zero external field. Both compounds are Heisenberg antiferromagnets with a small uniaxial anisotropy resulting from dipolar spin-spin interactions, which leads to a crossover in the critical dynamics close to the Néel temperature, TN. By taking advantage of the μ eV energy resolution of the spin-echo spectrometer, we have determined the dynamical critical exponents z for both longitudinal and transverse fluctuations. In MnF2, both the characteristic temperature for crossover from 3D Heisenberg to 3D Ising behavior and the exponents z in both regimes are consistent with predictions from the dynamical scaling theory. The amplitude ratio of longitudinal and transverse fluctuations also agrees with predictions. In Rb2MnF4 , the critical dynamics crosses over from the expected 2D Heisenberg behavior for T ≫TN to a scaling regime with exponent z =1.387 (4 ) , which has not been predicted by theory and may indicate the influence of long-range dipolar interactions.

  4. Antiferromagnetism of La2CuO(4-y) studied by muon-spin rotation

    Science.gov (United States)

    Uemura, Y. J.; Kossler, W. J.; Yu, X. H.; Kempton, J. R.; Schone, H. E.

    1987-01-01

    Zero-field spin precession of positive muons has been observed in the antiferromagnetic state of La2CuO(4-y). Sharp onsets of the sublattice magnetization are found at temperatures close to those of the susceptibility maxima of different specimens. The long-lived precession signal indicates a microscopically homogeneous distribution of spin density at each Cu atom below the Neel temperature. A combination of the present results and neutron-scattering studies indicates the ordered moment per Cu atom to be significantly less than 1 mu(B).

  5. Antiferromagnetic spintronics

    Science.gov (United States)

    Baltz, V.; Manchon, A.; Tsoi, M.; Moriyama, T.; Ono, T.; Tserkovnyak, Y.

    2018-01-01

    Antiferromagnetic materials could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics, and are capable of generating large magnetotransport effects. Intense research efforts over the past decade have been invested in unraveling spin transport properties in antiferromagnetic materials. Whether spin transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges currently being addressed. Antiferromagnetic spintronics started out with studies on spin transfer and has undergone a definite revival in the last few years with the publication of pioneering articles on the use of spin-orbit interactions in antiferromagnets. This paradigm shift offers possibilities for radically new concepts for spin manipulation in electronics. Central to these endeavors are the need for predictive models, relevant disruptive materials, and new experimental designs. This paper reviews the most prominent spintronic effects described based on theoretical and experimental analysis of antiferromagnetic materials. It also details some of the remaining bottlenecks and suggests possible avenues for future research. This review covers both spin-transfer-related effects, such as spin-transfer torque, spin penetration length, domain-wall motion, and "magnetization" dynamics, and spin-orbit related phenomena, such as (tunnel) anisotropic magnetoresistance, spin Hall, and inverse spin galvanic effects. Effects related to spin caloritronics, such as the spin Seebeck effect, are linked to the transport of magnons in antiferromagnets. The propagation of spin waves and spin superfluids in antiferromagnets is also covered.

  6. Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems

    KAUST Repository

    Manchon, Aurelien

    2018-01-29

    Spin-orbit coupling in inversion-asymmetric magnetic crystals and structures has emerged as a powerful tool to generate complex magnetic textures, interconvert charge and spin under applied current, and control magnetization dynamics. Current-induced spin-orbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as antiferromagnetic structures. The manipulation of magnetic order, domain walls and skyrmions by spin-orbit torques provides evidence of the microscopic interactions between charge and spin in a variety of materials and opens novel strategies to design spintronic devices with potentially high impact in data storage, nonvolatile logic, and magnonic applications. This paper reviews recent progress in the field of spin-orbitronics, focusing on theoretical models, material properties, and experimental results obtained on bulk noncentrosymmetric conductors and multilayer heterostructures, including metals, semiconductors, and topological insulator systems. Relevant aspects for improving the understanding and optimizing the efficiency of nonequilibrium spin-orbit phenomena in future nanoscale devices are also discussed.

  7. Geometric phase of a central spin coupled to an antiferromagnetic environment

    International Nuclear Information System (INIS)

    Yuan Xiaozhong; Zhu Kadi; Goan, H.-S.

    2010-01-01

    Using the spin-wave approximation, we study the geometric phase (GP) of a central spin (signal qubit) coupled to an antiferromagnetic (AF) environment under the application of an external global magnetic field. The external magnetic field affects the GP of the qubit directly and also indirectly through its effect on the AF environment. We find that when the applied magnetic field is increased to the critical magnetic field point, the AF environment undergoes a spin-flop transition, a first-order phase transition, and at the same time the GP of the qubit changes abruptly to zero. This sensitive change of the GP of a signal qubit to the parameter change of a many-body environment near its critical point may serve as another efficient tool or witness to study the many-body phase transition. The influences of the AF environment temperature and crystal anisotropy field on the GP are also investigated.

  8. RVB signatures in the spin dynamics of the square-lattice Heisenberg antiferromagnet

    Science.gov (United States)

    Ghioldi, E. A.; Gonzalez, M. G.; Manuel, L. O.; Trumper, A. E.

    2016-03-01

    We investigate the spin dynamics of the square-lattice spin-\\frac{1}{2} Heisenberg antiferromagnet by means of an improved mean-field Schwinger boson calculation. By identifying both, the long-range Néel and the RVB-like components of the ground state, we propose an educated guess for the mean-field magnetic excitation consisting on a linear combination of local and bond spin flips to compute the dynamical structure factor. Our main result is that when this magnetic excitation is optimized in such a way that the corresponding sum rule is fulfilled, we recover the low- and high-energy spectral weight features of the experimental spectrum. In particular, the anomalous spectral weight depletion at (π,0) found in recent inelastic neutron scattering experiments can be attributed to the interference of the triplet bond excitations of the RVB component of the ground state. We conclude that the Schwinger boson theory seems to be a good candidate to adequately interpret the dynamic properties of the square-lattice Heisenberg antiferromagnet.

  9. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    Spin squeezing and quantum correlations. K S MALLESH1, SWARNAMALA SIRSI2, MAHMOUD A A SBAIH1, P N DEEPAK1 and G RAMACHANDRAN3. 1Department of Studies in Physics, University of Mysore, Mysore 570 006, India. 2 Department of Physics, Yuvaraja's College, University of Mysore, Mysore 570 005, ...

  10. Persistence of the gapless spin liquid in the breathing kagome Heisenberg antiferromagnet

    Science.gov (United States)

    Iqbal, Yasir; Poilblanc, Didier; Thomale, Ronny; Becca, Federico

    2018-03-01

    The nature of the ground state of the spin S =1 /2 Heisenberg antiferromagnet on the kagome lattice with breathing anisotropy (i.e., with different superexchange couplings J▵ and J▿ within elementary up- and down-pointing triangles) is investigated within the framework of Gutzwiller projected fermionic wave functions and Monte Carlo methods. We analyze the stability of the U(1 ) Dirac spin liquid with respect to the presence of fermionic pairing that leads to a gapped Z2 spin liquid. For several values of the ratio J▿/J▵ , the size scaling of the energy gain due to the pairing fields and the variational parameters are reported. Our results show that the energy gain of the gapped spin liquid with respect to the gapless state either vanishes for large enough system size or scales to zero in the thermodynamic limit. Similarly, the optimized pairing amplitudes (responsible for opening the spin gap) are shown to vanish in the thermodynamic limit. Our outcome is corroborated by the application of one and two Lanczos steps to the gapless and gapped wave functions, for which no energy gain of the gapped state is detected when improving the quality of the variational states. Finally, we discuss the competition with the "simplex" Z2 resonating-valence-bond spin liquid, valence-bond crystal, and nematic states in the strongly anisotropic regime, i.e., J▿≪J▵ .

  11. Multicritical phase diagrams of the antiferromagnetic spin-3/2 Blume-Capel model

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)]. E-mail: keskin@erciyes.edu.tr; Ali Pinar, M. [Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Erdinc, Ahmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2006-04-24

    The antiferromagnetic spin-3/2 Blume-Capel model in an external magnetic field is investigated, and the phase diagrams are obtained in detail by using the cluster variation method. The model exhibits distinct critical regions, including the first-order, second-order and special points: two double critical points, a critical end point, a tricritical point and a zero-temperature critical point. The new phase diagram topology is also found that was not obtained previously. Comparison of the results with those of other studies on this, and closely related systems, is made.

  12. Multicritical phase diagrams of the antiferromagnetic spin-3/2 Blume-Capel model

    International Nuclear Information System (INIS)

    Keskin, Mustafa; Ali Pinar, M.; Erdinc, Ahmet; Canko, Osman

    2006-01-01

    The antiferromagnetic spin-3/2 Blume-Capel model in an external magnetic field is investigated, and the phase diagrams are obtained in detail by using the cluster variation method. The model exhibits distinct critical regions, including the first-order, second-order and special points: two double critical points, a critical end point, a tricritical point and a zero-temperature critical point. The new phase diagram topology is also found that was not obtained previously. Comparison of the results with those of other studies on this, and closely related systems, is made

  13. Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath

    Directory of Open Access Journals (Sweden)

    G. C. Fouokeng

    2014-01-01

    Full Text Available We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ transitions during a two-level crossing of a central electron spin (CES coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

  14. Padé approximations for the magnetic susceptibilities of Heisenberg antiferromagnetic spin chains for various spin values

    International Nuclear Information System (INIS)

    Law, J M; Benner, H; Kremer, R K

    2013-01-01

    The temperature dependence of the spin susceptibilities of S = 1, 3/2 , 2, 5/2 and 7/2 Heisenberg antiferromagnetic 1D spins chains with nearest-neighbor coupling was simulated via quantum Monte Carlo calculations, within the reduced temperature range of 0.005 ≤ T* ≤ 100, and fitted to a Padé approximation with deviations between the simulated and fitted data of the same order of magnitude as or smaller than the quantum Monte Carlo simulation error. To demonstrate the practicality of our theoretical findings, we compare these results with the susceptibility of the well known 1D chain compound TMMC ([(CH 3 ) 4 N[MnCl 3

  15. Antiferromagnetic spintronics

    KAUST Repository

    Baltz, V.

    2018-02-15

    Antiferromagnetic materials could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics, and are capable of generating large magnetotransport effects. Intense research efforts over the past decade have been invested in unraveling spin transport properties in antiferromagnetic materials. Whether spin transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges currently being addressed. Antiferromagnetic spintronics started out with studies on spin transfer and has undergone a definite revival in the last few years with the publication of pioneering articles on the use of spin-orbit interactions in antiferromagnets. This paradigm shift offers possibilities for radically new concepts for spin manipulation in electronics. Central to these endeavors are the need for predictive models, relevant disruptive materials, and new experimental designs. This paper reviews the most prominent spintronic effects described based on theoretical and experimental analysis of antiferromagnetic materials. It also details some of the remaining bottlenecks and suggests possible avenues for future research. This review covers both spin-transfer-related effects, such as spin-transfer torque, spin penetration length, domain-wall motion, and

  16. Parametric excitation of nuclear spin waves in MnCO3 antiferromagnetic crystals

    International Nuclear Information System (INIS)

    Govorkov, S.A.; Tulin, V.A.

    1976-01-01

    Parametric excitation of nuclear spin waves in the antiferromagnetic crystal MnCO 3 is investigated at 1080 MHz by the parallel pumping technique. Two threshold processes are observed in the experiments. One refers to spin wave excitation in a nuclear magnetic system and the other to excitation of magneto-elastic waves. The post-threshold sample susceptibility in such processes is studied. After the second threshold a very pronounced overheating of the nuclear magnetic system of the sample with respect to the lattice is observed. The nature of these overheating phenomena shows that two magneto-elastic oscillation branches are excited in the second threshold process. The dependence of the threshold field on wave vector is more complicated in a small magnetic field due to magnetization processes in the sample. In a large magnetic field complications are evoked by the magneto-elastic coupling

  17. Thermal conductivity of a quantum spin-1/2 antiferromagnetic chain with magnetic impurities

    International Nuclear Information System (INIS)

    Zviagin, A.A.

    2008-01-01

    We present an exact theory that describes how magnetic impurities change the behavior of the thermal conductivity for the integrable Heisenberg antiferromagnetic quantum spin-1/2 chain. Single magnetic impurities and a large concentration of impurities with similar values of the couplings to the host chain (a weak disorder) do not change the linear-in-temperature low-T behavior of the thermal conductivity: Only the slope of that behavior becomes smaller, compared to the homogeneous case. The strong disorder in the distribution of the impurity-host couplings produces more rapid temperature growth of the thermal conductivity, compared to the linear-in-T dependence of the homogeneous chain and the chain with weak disorder. Recent experiments on the thermal conductivity in inhomogeneous quasi-one-dimensional quantum spin systems manifest qualitative agreement with our results

  18. Ab initio calculations of incommensurate antiferromagnetic spin fluctuations in hcp iron under pressure

    Science.gov (United States)

    Thakor, V.; Staunton, J. B.; Poulter, J.; Ostanin, S.; Ginatempo, B.; Bruno, Ezio

    2003-05-01

    We present ab initio calculations of the static paramagnetic spin susceptibility for hcp iron at finite temperatures and for a range of pressures. The dominant magnetic fluctuations in hcp Fe are found to be incommensurate antiferromagnetic, characterized by the wave vector qinc=(0.56,0.22,0). We show that qinc is linked to a Fermi-surface nesting feature. For the lowest pressure ˜16 GPa at which hcp Fe forms, we find that these modes become unstable below a Néel temperature (TN) of 69 K. TN rapidly diminishes with increasing pressure. We therefore predict that hcp Fe will be found to have an incommensurate spin-density-wave-ordered state over a small pressure range starting with the onset of hcp phase. We note the coincidence with the superconductivity recently found in this material.

  19. Correlations, spin dynamics, defects: the highly-frustrated Kagome bilayer

    International Nuclear Information System (INIS)

    Bono, David; Limot, Laurent; Mendels, Philippe; Collin Gaston; Blanchard Nicole

    2005-01-01

    The SrCr 9p Ga 1 -2 -9p O 19 and Ba 2 Sn 2 ZnGa 10-7p Cr 7p O 22 compounds are two highly-frustrated magnets possessing a quasi-two-dimensional Kagome bilayer of spin 3/2 chromium ions with antiferromagnetic interactions. Their magnetic susceptibility was measured by local nuclear magnetic resonance and nonlocal (SQUID) techniques, and their low-temperature spin dynamics by muon spin resonance. Consistent with the theoretical picture drawn for geometrically frustrated systems, the Kagome bilayer is shown here to exhibit: (i) short range spin-spin correlations down to a temperature much lower than the Curie-Weiss temperature, no conventional long-range transition occurring; (ii) a Curie contribution to the susceptibility from paramagnetic defects generated by spin vacancies; (iii) low-temperature spin fluctuations, at least down to 30 mK, which are a trademark of a dynamical ground state. These properties point to a spin-liquid ground state, possibly built on resonating valence bonds with unconfined spinons as the magnetic excitations

  20. Direct evidence of spin frustration in the fcc antiferromagnet NiS sub 2

    CERN Document Server

    Matsuura, M; Endoh, Y; Hirota, K; Yamada, K

    2002-01-01

    NiS sub 2 is a well-known Mott insulator with anomalous antiferromagnetic long-range order of coexistent type I (Q sub M =(1,0,0), T sub N sub 1 =40 K) and type II (Q sub M =(1/2,1/2,1/2), T sub N sub 2 =30 K). Extensive neutron-scattering measurements reveal that magnetism in NiS sub 2 is governed by geometrical spin frustration, resulting in magnetic diffuse scattering extending along the fcc zone boundary. Although the diffuse scattering exists at temperatures as high as 250 K (6T sub N sub 1), it disappears rapidly below T sub N sub 2 , associated with minor crystal distortion. We observed a clear energy gap in addition to the low-energy spin-wave excitation at significantly below 30 K, and obtain evidence that degeneracy due to the coexistence of the two types of antiferromagnetism is relieved in the ground state via the reduction in symmetry due to distortion. (orig.)

  1. Quasi-two-dimensional spin correlations in the triangular lattice bilayer spin glass LuCoGaO4

    Science.gov (United States)

    Fritsch, K.; Ross, K. A.; Granroth, G. E.; Ehlers, G.; Noad, H. M. L.; Dabkowska, H. A.; Gaulin, B. D.

    2017-09-01

    We present a single-crystal time-of-flight neutron scattering study of the static and dynamic spin correlations in LuCoGaO4, a quasi-two-dimensional dilute triangular lattice antiferromagnetic spin-glass material. This system is based on Co2 + ions that are randomly distributed on triangular bilayers within the YbFe2O4 -type, hexagonal crystal structure. Antiferromagnetic short-range two-dimensional correlations at wave vectors Q =(" close=")1 /3 ,1 /3 ,L )">1 /3 ,1 /3 ,L develop within the bilayers at temperatures as high as | ΘCW|˜100 K and extend over roughly five unit cells at temperatures below Tg=19 K. These two-dimensional static correlations are observed as diffuse rods of neutron scattering intensity along c* and display a continuous spin freezing process in their energy dependence. Aside from exhibiting these typical spin-glass characteristics, this insulating material reveals a novel gapped magnetic resonant spin excitation at Δ E ˜12 meV localized around Q. The temperature dependence of the spin gap associated with this two-dimensional excitation correlates with the evolution of the static correlations into the spin-glass state ground state. We associate it with the effect of the staggered exchange field acting on the Seff=1 /2 Ising-like doublet of the Co2 + moments.

  2. Magnetic structure and spin dynamics of the quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8

    DEFF Research Database (Denmark)

    Kawasaki, Yu; Gavilano, Jorge L.; Keller, Lukas

    2011-01-01

    We report a neutron diffraction and muon spin relaxation mu SR study of static and dynamical magnetic properties of BaCo2V2O8, a quasi-one-dimensional spin-chain system. A proposed model for the antiferromagnetic structure includes: a propagation vector (k) over right arrow (AF) = (0......,0,1), independent of external magnetic fields for fields below a critical value H-c(T). The ordered moments of 2.18 mu(B) per Co ion are aligned along the crystallographic c axis. Within the screw chains, along the c axis, the moments are arranged antiferromagnetically. In the basal planes the spins are arranged...... ferromagnetically (forming zigzag paths) along one of the axes and antiferromagnetically along the other. The temperature dependence of the sublattice magnetization is consistent with the expectations of the three-dimensional (3D) Ising model. A similar behavior is observed for the internal static fields...

  3. Magnetic correlations in the intermetallic antiferromagnet Nd3Co4Sn13

    Science.gov (United States)

    Wang, C. W.; Lin, J. W.; Lue, C. S.; Liu, H. F.; Kuo, C. N.; Mole, R. A.; Gardner, J. S.

    2017-11-01

    Specific heat, magnetic susceptibility, and neutron scattering have been used to investigate the nature of the spin system in the antiferromagnet Nd3Co4Sn13. At room temperature Nd3Co4Sn13 has a cubic, Pm-3n structure similar to Yb3Rh4Sn13. Antiferromagnetic interactions between, Nd3+ ions dominate the magnetic character of this sample and at 2.4 K the Nd spins enter a long range order state with a magnetic propagation vector q  =  (0 0 0) with an ordered moment of 1.78(2) µ B at 1.5 K. The magnetic Bragg intensity grows very slowly below 1 K, reaching ~2.4 µ B at 350 mK. The average magnetic Nd3+ configuration corresponds to the 3D irreducible representation Γ7. This magnetic structure can be viewed as three sublattices of antiferromagnetic spin chains coupled with each other in the 120°-configuration. A well-defined magnetic excitation was measured around the 1 1 1 zone centre and the resulting dispersion curve is appropriate for an antiferromagnet with a gap of 0.20(1) meV.

  4. Search for the Heisenberg spin glass on rewired cubic lattices with antiferromagnetic interaction

    International Nuclear Information System (INIS)

    Surungan, Tasrief

    2016-01-01

    Spin glass (SG) is a typical magnetic system which is mainly characterized by a frozen random spin orientation at low temperatures. Frustration and randomness are considered to be the key ingredients for the existence of SGs. Previously, Bartolozzi et al . [Phys. Rev. B73, 224419 (2006)] found that the antiferromagnetic (AF) Ising spins on scale free network (SFN) exhibited SG behavior. This is purely AF system, a new type of SG different from the canonical one which requires the presence of both FM and AF couplings. In this new system, frustration is purely due to a topological factor and its randomness is brought by irregular connectivity. Recently, it was reported that the AF Heisenberg model on SFN exhibited SG behavior [Surungan et al ., JPCS, 640, 012005 (2015)/doi:10.1088/1742-6596/640/1/012005]. In order to accommodate the notion of spatial dimension, we further investigated this type of system by studying an AF Heisenberg model on rewired cubic lattices, constructed by adding one extra bond randomly connecting each spin to one of its next-nearest neighbors. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter to search for the existence of SG phase. (paper)

  5. Long-range inverse two-spin correlations in one-dimensional Potts lattices

    International Nuclear Information System (INIS)

    Tejero, C.F.; Cuesta, J.A.; Brito, R.

    1989-01-01

    The inverse two-spin correlation function of a one-dimensional three-state Potts lattice with constant nearest-neighbor interactions in a uniform external field is derived exactly. It is shown that the external field induces long-range correlations. The inverse two-spin correlation function decays in a monotonic exponential fashion for a ferromagnetic lattice, while it decays in an oscillatory exponential fashion for an antiferromagnetic lattice. With no external field the inverse two-spin correlation function has a finite range equal to that of the interactions

  6. Spin Dynamics and Critical Fluctuations in a Two-Dimensional Random Antiferromagnet

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.

    1975-01-01

    A comprehensive elastic- and inelastic-neutron-scattering study of the binary mixed antiferromagnet Rb2Mn0.5Ni0.5F4 has been carried out. The pure materials, Rb2MnF4 and Rb2NiF4 are [2d] near-Heisenberg antiferromagnets of the K2NiF4 type. Elastic-scattering experiments demonstrate that the Mn...... like the sublattice magnetization while the excitations at larger wave vectors remain well defined through TN and only slightly renormalized from their T=0 energies. Critical scattering measurements of the staggered susceptibility and the correlation length have been carried out between 69 and 120 K...

  7. Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

    2015-05-07

    Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

  8. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    Science.gov (United States)

    Vaknin, David; Zhang, Qiang; Peterson, Spencer; Dennis, Kevin; Tian, Wei

    2015-03-01

    Structure and complex magnetic properties of CeMnAsO, a parent compound of the ``1111''-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. Whereas there is no structural transition from the P4/nmm tetragonal phase below 420 K, CeMnAsO undergoes a C-type antiferromagnetic order with Mn2+ (S = 5 / 2) moments pointing along the c-axis below a relatively high Néel temperature of TN = 345 K. Below TSR = 35 K, two instantaneous transitions occur where the Mn moments reorient to the ab-plane preserving the C-type magnetic order, and Ce moments undergo long-range AFM ordering with moments in the ab-plane. Another transition to a noncollinear magnetic structure occurs below 7 K. We find that CeMnAsO primarily falls into the category of a local-moment antiferromagnetic insulator in which the nearest-neighbor interaction (J1) is dominant. The spin reorientation transition driven by the coupling between rare earth Ce and transition metal seems to be common to Mn, Fe and Cr ion,but not to Co and Ni ions in the iso-structural oxypnictides. Supported by the Office of Basic Energy Sciences, US-DOE, Number DE-AC02-07CH11358.

  9. A separation of antiferromagnetic spin motion modes in the training effect of exchange biased Co/CoO film with in-plane anisotropy

    International Nuclear Information System (INIS)

    Wu, R.; Yun, C.; Ding, S. L.; Wen, X.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Du, H. L.; Yang, J. B.

    2016-01-01

    The motion of antiferromagnetic interfacial spins is investigated through the temperature evolution of training effect in a Co/CoO film with in-plane biaxial anisotropy. Significant differences in the training effect and its temperature dependence are observed in the magnetic easy axis and hard axis (HA) and ascribed to the different motion modes of antiferromagnetic interfacial spins, the collective spin cluster rotation (CSR) and the single spin reversal (SSR), caused by different magnetization reversal modes of ferromagnetic layer. These motion modes of antiferromagnetic spins are successfully separated using a combination of an exponential function and a classic n −1/2 function. A larger CSR to SSR ratio and a shorter lifetime of CSR found in the HA indicates that the domain rotation in the ferromagnetic layer tends to activate and accelerate a CSR mode in the antiferromagnetic spins.

  10. Search for the Heisenberg spin glass on rewired square lattices with antiferromagnetic interaction

    International Nuclear Information System (INIS)

    Surungan, Tasrief; Bansawang, B.J.; Tahir, Dahlang

    2016-01-01

    Spin glass (SG) is a typical magnetic system with frozen random spin orientation at low temperatures. The system exhibits rich physical properties, such as infinite number of ground states, memory effect, and aging phenomena. There are two main ingredients considered to be pivotal for the existence of SG behavior, namely, frustration and randomness. For the canonical SG system, frustration is led by the presence of competing interaction between ferromagnetic (FM) and antiferromagnetic (AF) couplings. Previously, Bartolozzi et al. [Phys. Rev. B73, 224419 (2006)], reported the SG properties of the AF Ising spins on scale free network (SFN). It is a new type of SG, different from the canonical one which requires the presence of both FM and AF couplings. In this new system, frustration is purely caused by the topological factor and its randomness is related to the irregular connectvity. Recently, Surungan et. al. [Journal of Physics: Conference Series, 640, 012001 (2015)] reported SG bahavior of AF Heisenberg model on SFN. We further investigate this type of system by studying an AF Heisenberg model on rewired square lattices. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter to search for the existence of SG phase.

  11. An S=1/2 impurity spin in the antiferromagnetic S=1 bond-alternating chain

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Nobuyuki [Gifu National College of Technology, Dept. of Fundamental Science, Gifu (Japan); Hikihara, Toshiya [National Inst. for Materials Science, Computational Material Research Group, Tsukuba, Ibaraki (Japan); Kaburagi, Makoto [Kobe Univ., Faculty of Cross-Cultural Studies, Kobe, Hyogo (Japan); Tonegawa, Takashi [Fukui Univ. of Technology, Dept. of Mechanical Engineering, Fukui (Japan)

    2002-06-01

    We explore low-lying excited states as well as the ground state of the antiferromagnetic S=1 bond-alternating chain with an S=1/2 impurity spin. For the case where the ground-state phase of the host system is the Haldane phase, we review a numerical analysis of the electron-spin-resonance experimental results on the NENP: Cu{sup 2+} system. For the case where the ground-state phase of the host system is the dimer phase, on the other hand, we calculate, using the exact-diagonalization method, the dependences of the energy differences between the ground and low-lying excited states upon both the impurity-host exchange constant and the single-ion-type anisotropy constant, and also calculate, using the density-matrix renormalization-group method, the external-magnetic-field dependence of the impurity-spin magnetization in the ground state. In these calculations, we keep the NTENP: Cu{sup 2+} system in mind to choose the value of the bond-alternation parameter. We find that a few low-lying excited states which are expected from the valence-bond-solid picture appear as the impurity states in the energy gap between the singlet ground and triplet first-excited states (the dimer gap). Furthermore, for certain values of the above constants, we find that the impurity-spin magnetization shows a clear jump at a magnetic field which is in the dimer-gap region or in the magnetization-plateau region of the host system, and also that the impurity-spin magnetization has a magnetic-field region where it decreases as a function of the magnetic field. (author)

  12. Coexistence of antiferromagnetism and spin polarization in double perovskite SrLaVMoO6

    International Nuclear Information System (INIS)

    Asano, H; Gotoh, H; Matsushima, H; Takeda, Y; Zhong, J; Rajanikanth, A; Hono, K

    2010-01-01

    The magnetic and transport properties of SrLaVMoO 6 bulk samples with an ordered double perovskite structure have been investigated. Magnetization measurements have indicated that the SrLaVMoO 6 compound exhibits a cusp at 125 K, which is attributable to an antiferromagnetic transition. Electrical resistivity ρ for the compound showed metallic temperature dependence from 10 to 300 K, and a spin polarization P value was measured to be 0.50 using the point-contact Andreev reflection (PCAR) technique. It has been found from X-ray photoemission spectroscopy (XPS) study that SrLaVMoO 6 closely resembles the half-metallic Sr 2 FeMoO 6 in the electronic state of the Mo.

  13. A spin-valve-like magnetoresistance of an antiferromagnet-based tunnel junction

    Czech Academy of Sciences Publication Activity Database

    Park, B.G.; Wunderlich, Joerg; Martí, X.; Holý, V.; Kurosaki, Y.; Yamada, M.; Yamamoto, H.; Nishide, A.; Hayakawa, J.; Takahashi, H.; Shick, Alexander; Jungwirth, Tomáš

    2011-01-01

    Roč. 10, č. 5 (2011), s. 347-351 ISSN 1476-1122 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510; GA MŠk(CZ) 7E08087 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 214499 - NAMASTE; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10100520 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 32.841, year: 2011

  14. Theory of Topological Spin Hall Effect in Antiferromagnetic Skyrmion: Impact on Current-induced Motion

    KAUST Repository

    Akosa, Collins Ashu

    2017-09-09

    We demonstrate that the nontrivial magnetic texture of antiferromagnetic skyrmions (AFM-Sks) promotes a non-vanishing topological spin Hall effect (TSHE) on the flowing electrons. This results in a substantial enhancement of the non-adiabatic torque and hence improves the skyrmion mobility. This non-adiabatic torque increases when decreasing the skyrmion size, and therefore scaling down results in a much higher torque efficiency. In clean AFM-Sks, we find a significant boost of the TSHE close to van Hove singularity. Interestingly, this effect is enhanced away from the band gap in the presence of non-magnetic interstitial defects. Furthermore, unlike their ferromagnetic counterpart, TSHE in AFM-Sks increases with increase in disorder strength thus opening promising avenues for materials engineering of this effect.

  15. Glass-like recovery of antiferromagnetic spin ordering in a photo-excited manganite Pr0.7Ca0.3MnO3

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, S. Y.; Langner, M. C.; Zhu, Y.; Chuang, Y. -D.; Rini, M.; Glover, T. E.; Hertlein, M. P.; Gonzalez, A.G. Cruz; Tahir, N.; Tomioka, Y.; Tokura, Y.; Hussain, Z.; Schoenlein, R. W.

    2014-01-16

    Electronic orderings of charges, orbitals and spins are observed in many strongly correlated electron materials, and revealing their dynamics is a critical step toward understanding the underlying physics of important emergent phenomena. Here we use time-resolved resonant soft x-ray scattering spectroscopy to probe the dynamics of antiferromagnetic spin ordering in the manganite Pr0:7Ca0:3MnO3 following ultrafast photo-exitation. Our studies reveal a glass-like recovery of the spin ordering and a crossover in the dimensionality of the restoring interaction from quasi-1D at low pump fluence to 3D at high pump fluence. This behavior arises from the metastable state created by photo-excitation, a state characterized by spin disordered metallic droplets within the larger charge- and spin-ordered insulating domains. Comparison with time-resolved resistivity measurements suggests that the collapse of spin ordering is correlated with the insulator-to-metal transition, but the recovery of the insulating phase does not depend on the re-establishment of the spin ordering.

  16. Anisotropic spin-spin correlations in Mn1/X(111) (X= Pd, Pt, Ag, and Au)

    Science.gov (United States)

    Dos Santos Dias, M.; Staunton, J. B.; Deak, A.; Szunyogh, L.

    2011-02-01

    We present a finite-temperature theory of the anisotropic spin-spin correlations in magnetic metallic monolayers deposited on a suitable substrate. The spins are the local moments set up by the itinerant electrons, and the key concept is the relativistic disordered local moment state, which represents the paramagnetic state of a set of local moments. The spin-spin correlations between these local moments are then extracted using the linear-response formalism. The anisotropy is included in a fully relativistic treatment, based on the Dirac equation, and has a qualitative impact on noncollinear magnetic states by lifting their chiral degeneracy. The theory is applied to Mn monolayers on the hexagonal (111) surfaces of Pd, Pt, Ag, and Au. The presence of competing exchange interactions is highlighted by choosing different substrates, which favor either the row-wise antiferromagnetic state or the chiral triangular Néel state. We correlate the electronic structure with the magnetic properties by comparing filled with partially filled substrate d bands, and low versus high atomic number. The disagreement between theory and experiment for Mn1/Ag(111) is addressed, and the nature of the magnetic domains found experimentally is suggested to be chiral.

  17. Quantum antiferromagnetic Heisenberg half-odd-integer spin model as the entanglement Hamiltonian of the integer-spin Affleck-Kennedy-Lieb-Tasaki states

    Science.gov (United States)

    Rao, Wen-Jia; Zhang, Guang-Ming; Yang, Kun

    2016-03-01

    Applying a symmetric bulk bipartition to the one-dimensional Affleck-Kennedy-Lieb-Tasaki valence-bond solid (VBS) states for the integer spin-S Haldane gapped phase, we can create an array of fractionalized spin-S /2 edge states with the super unit cell l in the reduced bulk system, and the topological properties encoded in the VBS wave functions can be revealed. The entanglement Hamiltonian (EH) with even l corresponds to the quantum antiferromagnetic Heisenberg spin-S /2 model. For the even integer spins, the EH still describes the Haldane gapped phase. For the odd integer spins, however, the EH just corresponds to the quantum antiferromagnetic Heisenberg half-odd integer-spin model with spinon excitations, characterizing the critical point separating the topological Haldane phase from the trivial gapped phase. Our results thus demonstrate that the topological bulk property not only determines its fractionalized edge states but also the quantum criticality associated with the topological phase, where the elementary excitations are precisely those fractionalized edge degrees of freedom confined in the bulk of the topological phase.

  18. Surface-spin magnetism of antiferromagnetic NiO in nanoparticle and bulk morphology

    International Nuclear Information System (INIS)

    Jagodic, M; Jaglicic, Z; Jelen, A; Dolinsek, J; Lee, Jin Bae; Kim, Hae Jin; Kim, Young-Min

    2009-01-01

    The surface-spin magnetism of the antiferromagnetic (AFM) material NiO in nanoparticle and bulk morphology was investigated by magnetic measurements (temperature-dependent zero-field-cooled (zfc) and field-cooled (fc) dc susceptibility, ac susceptibility and zfc and fc hysteresis loops). We addressed the question of whether the multisublattice ordering of the uncompensated surface spins and the exchange bias (EB) effect are only present in the nanoparticles, originating from their high surface-to-volume ratio or if these surface phenomena are generally present in the AFM materials regardless of their bulky or nanoparticle morphology, but the effect is just too small to be detected experimentally in the bulk due to a very small surface magnetization. Performing experiments on the NiO nanoparticles of different sizes and bulk NiO grains, we show that coercivity enhancement and hysteresis loop shift in the fc experiments, considered to be the key experimental manifestations of multisublattice ordering and the EB effect, are true nanoscale phenomena only present in the nanoparticles and absent in the bulk.

  19. Terahertz-Frequency Spin Hall Auto-oscillator Based on a Canted Antiferromagnet

    Science.gov (United States)

    Sulymenko, O. R.; Prokopenko, O. V.; Tiberkevich, V. S.; Slavin, A. N.; Ivanov, B. A.; Khymyn, R. S.

    2017-12-01

    We propose a design of a terahertz-frequency signal generator based on a layered structure consisting of a current-driven platinum (Pt) layer and a layer of an antiferromagnet (AFM) with easy-plane anisotropy, where the magnetization vectors of the AFM sublattices are canted inside the easy plane by the Dzyaloshinskii-Moriya interaction (DMI). The dc electric current flowing in the Pt layer creates due to the spin Hall effect, a perpendicular spin current that, being injected in the AFM layer, tilts the DMI-canted AFM sublattices out of the easy plane, thus exposing them to the action of a strong internal exchange magnetic field of the AFM. The sublattice magnetizations, along with the small net magnetization vector mDMI of the canted AFM, start to rotate about the hard anisotropy axis of the AFM with the terahertz frequency proportional to the injected spin current and the AFM exchange field. The rotation of the small net magnetization mDMI results in the terahertz-frequency dipolar radiation that can be directly received by an adjacent (e.g., dielectric) resonator. We demonstrate theoretically that the radiation frequencies in the range f =0.05 - 2 THz are possible at the experimentally reachable magnitudes of the driving current density, and we evaluate the power of the signal radiated into different types of resonators. This power increases with the increase of frequency f , and it can exceed 1 μ W at f ˜0.5 THz for a typical dielectric resonator of the electric permittivity ɛ ˜10 and a quality factor Q ˜750 .

  20. Single-pulse terahertz coherent control of spin resonance in the canted antiferromagnet YFeO3, mediated by dielectric anisotropy

    DEFF Research Database (Denmark)

    Jin, Zuanming; Mics, Zoltán; Ma, Guohong

    2013-01-01

    We report on the coherent control of terahertz (THz) spin waves in a canted antiferromagnet yttrium orthoferrite, YFeO3, associated with a quasiferromagnetic (quasi-FM) spin resonance at a frequency of 0.3 THz, using a single-incident THz pulse. The spin resonance is excited impulsively by the ma...... polarization of the THz oscillation at the spin resonance frequency, suggests a key role of magnon–phonon coupling in spin-wave energy dissipation....

  1. The finite temperature density matrix and two-point correlations in the antiferromagnetic XXZ chain

    Science.gov (United States)

    Göhmann, Frank; Hasenclever, Nils P.; Seel, Alexander

    2005-10-01

    We derive finite temperature versions of integral formulae for the two-point correlation functions in the antiferromagnetic XXZ chain. The derivation is based on the summation of density matrix elements characterizing a finite chain segment of length m. On this occasion we also supply a proof of the basic integral formula for the density matrix presented in an earlier publication.

  2. Antiferromagnetic versus spin-glass like behavior in MnIn{sub 2}S{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Sagredo, V. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de los Andes, Merida (Venezuela)]. E-mail: sagredo@ula.ve; Moron, M.C. [Instituto de Ciencia de Materiales de Aragon, C.S.I.C.-Universidad de Zaragoza, E-50009, Zaragoza (Spain); Betancourt, L. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de los Andes, Merida (Venezuela); Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Merida (Venezuela)

    2007-05-15

    The low-temperature magnetic properties of MnIn{sub 2}S{sub 4} have been studied using AC magnetic susceptibility and magnetization experiments. High-temperature susceptibility fits indicate the presence of antiferromagnetic interactions. Low-field magnetization data show a peak at 5.6{+-}0.1 K, below which strong irreversibility is observed between zero-field-cooled (ZFC) and field-cooled (FC) cycles suggesting that the observed peak corresponds to a spin-glass-like transition instead of the antiferromagnetic one previously reported. Further evidence of this magnetic state comes from AC susceptibility data at different frequencies. The in-phase component {chi}'(T) exhibits the behavior expected of spin glasses, i.e. a shift of the cusp to higher temperatures for higher frequencies.

  3. Quantum-Classical Phase Transition of the Escape Rate of Two-Sublattice Antiferromagnetic Large Spins

    Science.gov (United States)

    Owerre, Solomon Akaraka; Paranjape, M. B.

    2014-11-01

    The Hamiltonian of a two-sublattice antiferromagnetic spins, with single (hard-axis) and double ion anisotropies described by H = J {\\hat S}1...\\hatS 2-2Jz \\hat {S}1z\\hat {S}2z+K(\\hat {S}1z2 +\\hat {S}2z2) is investigated using the method of effective potential. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and reduced mass. We study the quantum-classical phase transition of the escape rate of this model. We show that the first-order phase transition for this model sets in at the critical value Jc = (Kc+Jz, c)/2 while for the anisotropic Heisenberg coupling H = J(S1xS2x +S1yS2y) + JzS1zS2z + K(S1z2+ S2z2) we obtain Jc = (2Kc-Jz, c)/3. The phase diagrams of the transition are also studied.

  4. Spin glass behavior of the antiferromagnetic Heisenberg model on scale free network

    International Nuclear Information System (INIS)

    Surungan, Tasrief; Zen, Freddy P; Williams, Anthony G

    2015-01-01

    Randomness and frustration are considered to be the key ingredients for the existence of spin glass (SG) phase. In a canonical system, these ingredients are realized by the random mixture of ferromagnetic (FM) and antiferromagnetic (AF) couplings. The study by Bartolozzi et al. [Phys. Rev. B73, 224419 (2006)] who observed the presence of SG phase on the AF Ising model on scale free network (SFN) is stimulating. It is a new type of SG system where randomness and frustration are not caused by the presence of FM and AF couplings. To further elaborate this type of system, here we study Heisenberg model on AF SFN and search for the SG phase. The canonical SG Heisenberg model is not observed in d-dimensional regular lattices for (d ≤ 3). We can make an analogy for the connectivity density (m) of SFN with the dimensionality of the regular lattice. It should be plausible to find the critical value of m for the existence of SG behaviour, analogous to the lower critical dimension (d l ) for the canonical SG systems. Here we study system with m = 2, 3, 4 and 5. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter. We observed SG phase for each value of m and estimated its corersponding critical temperature. (paper)

  5. Antiferromagnetic ordering in spin-chain multiferroic Gd{sub 2}BaNiO{sub 5} studied by electronic spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. M.; Ruan, M. Y.; Cheng, J. J.; Sun, Y. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ouyang, Z. W., E-mail: zwouyang@mail.hust.edu.cn; Xia, Z. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Rao, G. H. [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-06-14

    High-field electron spin resonance (ESR) has been employed to study the antiferromagnetic (AFM) ordering state (T < T{sub N} = 55 K) of spin-chain multiferroic Gd{sub 2}BaNiO{sub 5}. The spin reorientation at T{sub SR} = 24 K is well characterized by the temperature-dependent ESR spectra. The magnetization data evidence a field-induced spin-flop transition at 2 K. The frequency-field relationship of the ESR data can be explained by conventional AFM resonance theory with uniaxial anisotropy, in good agreement with magnetization data. Related discussion on zero-field spin gap is presented.

  6. Dynamic magnetic behavior of the mixed spin (2, 5/2) Ising system with antiferromagnetic/antiferromagnetic interactions on a bilayer square lattice

    International Nuclear Information System (INIS)

    Ertaş Mehmet; Keskin Mustafa

    2013-01-01

    Using the mean-field theory and Glauber-type stochastic dynamics, we study the dynamic magnetic properties of the mixed spin (2, 5/2) Ising system for the antiferromagnetic/antiferromagnetic (AFM/AFM) interactions on the bilayer square lattice under a time varying (sinusoidal) magnetic field. The time dependence of average magnetizations and the thermal variation of the dynamic magnetizations are examined to calculate the dynamic phase diagrams. The dynamic phase diagrams are presented in the reduced temperature and magnetic field amplitude plane and the effects of interlayer coupling interaction on the critical behavior of the system are investigated. We also investigate the influence of the frequency and find that the system displays richer dynamic critical behavior for higher values of frequency than that of the lower values of it. We perform a comparison with the ferromagnetic/ferromagnetic (FM/FM) and AFM/FM interactions in order to see the effects of AFM/AFM interaction and observe that the system displays richer and more interesting dynamic critical behaviors for the AFM/AFM interaction than those for the FM/FM and AFM/FM interactions. (general)

  7. Antiferromagnetic, charge-transfer, and pairing correlations in the three-band Hubbard model

    Science.gov (United States)

    Scalettar, R. T.; Scalapino, D. J.; Sugar, R. L.; White, S. R.

    1991-07-01

    The CuO2 sheets common to the superconducting cuprates are believed to be characterized by a charge-transfer gap in their insulating antiferromagnetic state. The three-band Hubbard model with an on-site Cu Coulomb interaction Ud, which is large compared to the difference in energy ɛ between the O and Cu sites, provides a basic model for such a system. We have carried out Lanczos and Monte Carlo studies of a CuO2 lattice described by a three-band Hubbard model. For Ud large compared with ɛ, and ɛ comparable to or larger than the bandwidth of the lower hole band, we find strong antiferromagnetic correlations and evidence for a charge-transfer gap at a filling of one hole per Cu. The antiferromagnetic correlations decrease with either hole or electron doping, and we see that the additional holes go primarily on the O sites, while additional electrons go onto the Cu sites. For large values of the intersite Cu-O Coulomb interaction V, the hole-doped system exhibits a charge-transfer instability. As V is reduced, this is reflected as a peak in the charge-transfer susceptibility near ɛ+2V~=Ud, which we find is washed out by the strong Cu-O hybridization at realistic values of V. Attractive pairing interactions are found in both the d-wave and extended s*-wave channels near the antiferromagnetic boundary.

  8. Controllable magnetic correlation between two impurities by spin-orbit coupling in graphene.

    Science.gov (United States)

    Hu, F M; Kou, Liangzhi; Frauenheim, Thomas

    2015-03-10

    Two magnetic impurities on the edge of a zigzag graphene nanoribbon strongly interact with each other via indirect coupling, which can be mediated by conducting carriers. By means of Quantum Monte Carlo (QMC) simulations, we find that the spin-orbit coupling λ and the chemical potential μ in system can be used to drive the transition of local-spin exchange from ferromagnetism to anti-ferromagnetism. Since the tunable ranges for λ and μ in graphene are experimentally reachable, we thus open the possibilities for its device application. The symmetry in spatial distribution is broken by the vertical and the transversal spin-spin correlations due to the effect of spin-orbit coupling, leading to the spatial anisotropy of spin exchange, which distinguish our findings from the case in normal Fermi liquid.

  9. Spin-spin correlations in the tt'-Hubbard model

    International Nuclear Information System (INIS)

    Husslein, T.; Newns, D.M.; Mattutis, H.G.; Pattnaik, P.C.; Morgenstern, I.; Singer, J.M.; Fettes, W.; Baur, C.

    1994-01-01

    We present calculations of the tt'-Hubbard model using Quantum Monte Carlo techniques. The parameters are chosen so that the van Hove Singularity in the density of states and the Fermi level coincide. We study the behaviour of the system with increasing Hubbard interaction U. Special emphasis is on the spin-spin correlation (SSC). Unusual behaviour for large U is observed there and in the momentum distribution function (n(q)). (orig.)

  10. Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4.

    Science.gov (United States)

    Sushkov, A B; Tchernyshyov, O; Ratcliff, W; Cheong, S W; Drew, H D

    2005-04-08

    The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, an excellent realization of the Heisenberg antiferromagnet on the pyrochlore network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at T(c)=12.5 K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By using infrared spectroscopy and published data on magnetic specific heat, we demonstrate that the frequency of an optical phonon triplet in ZnCr2O4 tracks the nearest-neighbor spin correlations above T(c). The splitting of the phonon triplet below T(c) provides a way to measure the spin-Peierls order parameter.

  11. Coexistence of antiferromagnetic and ferromagnetic spin correlations in Ca(Fe1-xCox)2As2 revealed by As75 nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J.; Wiecki, P.; Ran, S.; Bud' ko, S. L.; Canfield, P. C.; Furukawa, Y.

    2016-11-22

    Recent nuclear magnetic resonance (NMR) measurements revealed the coexistence of stripe-type antiferromagnetic (AFM) and ferromagnetic (FM) spin correlations in both the hole- and electron-doped BaFe 2 As 2 families of iron-pnictide superconductors by a Korringa ratio analysis. Motivated by the NMR work, we investigate the possible existence of FM fluctuations in another iron-pnictide superconducting family, Ca ( Fe 1 - x Co x ) 2 As 2 . We reanalyzed our previously reported data in terms of the Korringa ratio and found clear evidence for the coexistence of stripe-type AFM and FM spin correlations in the electron-doped CaFe 2 As 2 system. These NMR data indicate that FM fluctuations exist in general in iron-pnictide superconducting families and thus must be included to capture the phenomenology of the iron pnictides.

  12. Antiferromagnetic skyrmions

    Science.gov (United States)

    Tretiakov, Oleg; Barker, Joseph

    Skyrmions are topologically protected entities in magnetic materials which have the potential to be used in spintronics for information storage and processing. However, skyrmions in ferromagnets have some intrinsic difficulties which must be overcome to use them for spintronic applications, such as the inability to move straight along current. We show that skyrmions can also be stabilized and manipulated in antiferromagnetic materials. An antiferromagnetic skyrmion is a compound topological object with a similar but of opposite sign spin texture on each sublattice, which e.g. results in a complete cancelation of the Magnus force. We find that the composite nature of antiferromagnetic skyrmions gives rise to different dynamical behavior, both due to an applied current and temperature effects. O.A.T. and J.B. acknowledge support by the Grants-in-Aid for Scientific Research (Nos. 25800184, 25247056, 25220910 and 15H01009) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan and SpinNet.

  13. Spin-flip transition and Faraday effect in antiferromagnet KMnF3 in megagauss magnetic field

    International Nuclear Information System (INIS)

    Mukhin, A.A.; Plis, V.I.; Popov, A.I.; Zvezdin, A.K.; Platonov, V.; Tatsenko, O.M.

    1998-01-01

    Faraday effect in the antiferromagnet KMnF 3 has been investigated in pulse explosive fields up to 500 T at T=78 K. The laser wavelength 0.63 μm was used in the experiment. The magnetic field dependence of Faraday rotation in this antiferromagnet shows a unique feature of a lack of saturation effect in the fields up to 500 T whereas critical field of spin-flip transition is about 120 T. The theoretical analysis of microscopic nature of Faraday rotation, including the diamagnetic, magneto-dipole and paramagnetic mechanisms has been performed. The strong competition of these mechanisms is important to explain the extremely small value of the effect and its unusual magnetic field dependence

  14. Finite-temperature correlation functions of Heisenberg antiferromagnet

    International Nuclear Information System (INIS)

    Izergin, A.G.; Korepin, V.E.; Slavnov, N.A.

    1988-01-01

    The finite-temperature correlation functions in the one-dimensional Heisenberg XXZ magnet are investigated in the framework of the quantum inverse scattering method. On the transition to nonzero temperatures, it is necessary in this case to solve a number of basically new problems. The main one of these is related to the fact that the ground state of the Hamiltonian (physical vacuum) at nonzero temperature (more precisely, the state of thermodynamic equilibrium) includes many species of particles - not only elementary particles but also bound states of them. We give an appropriate generalization of the method

  15. Effective S =2 antiferromagnetic spin chain in the salt (o -MePy-V)FeCl4

    Science.gov (United States)

    Iwasaki, Y.; Kida, T.; Hagiwara, M.; Kawakami, T.; Hosokoshi, Y.; Tamekuni, Y.; Yamaguchi, H.

    2018-02-01

    We present a model compound for the S =2 antiferromagnetic (AF) spin chain composed of the salt (o -MePy-V ) FeCl4 . Ab initio molecular-orbital calculations indicate the formation of a partially stacked two-dimensional (2D) spin model comprising five types of exchange interactions between S =1 /2 and S =5 /2 spins, which locate on verdazyl radical and Fe ion, respectively. The magnetic properties of the synthesized crystals indicate that the dominant interaction between the S =1 /2 and S =5 /2 spins stabilizes an S =2 spin in the low-temperature region, and an effective S =2 AF chain is formed for T ≪10 K and H chain. At higher fields above quantitatively 4 T, the magnetization curve assumes two-thirds of the full saturation value for fields between 4 and 20 T, and approaches saturation at ˜40 T. The spin model in the high-field region can be considered as a quasi-2D S =1 /2 honeycomb lattice under an effective internal field caused by the fully polarized S =5 /2 spin.

  16. Direct Observation of Localized Spin Antiferromagnetic Transition in PdCrO2 by Angle-Resolved Photoemission Spectroscopy

    Science.gov (United States)

    Noh, Han-Jin; Jeong, Jinwon; Chang, Bin; Jeong, Dahee; Moon, Hyun Sook; Cho, En-Jin; Ok, Jong Mok; Kim, Jun Sung; Kim, Kyoo; Min, B. I.; Lee, Han-Koo; Kim, Jae-Young; Park, Byeong-Gyu; Kim, Hyeong-Do; Lee, Seongsu

    2014-01-01

    We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin ordering pattern of Cr3+ ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements, and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system. PMID:24419488

  17. Unusual magnetic excitations in the weakly ordered spin- 12 chain antiferromagnet Sr2CuO3: Possible evidence for Goldstone magnon coupled with the amplitude mode

    International Nuclear Information System (INIS)

    Sergeicheva, E. G.; Sosin, S. S.; Prozorova, L. A.; Gu, G. D.; Zaliznyak, I. A.

    2017-01-01

    We report on an electron spin resonance (ESR) study of a nearly one-dimensional (1D) spin-1/2 chain antiferromagnet, Sr 2 CuO 3 , with extremely weak magnetic ordering. The ESR spectra at T > T N , in the disordered Luttinger-spin-liquid phase, reveal nearly ideal Heisenberg-chain behavior with only a very small, field-independent linewidth, ~1/T. In the ordered state, below T N , we identify field-dependent antiferromagnetic resonance modes, which are well described by pseudo-Goldstone magnons in the model of a collinear biaxial antiferromagnet. Additionally, we observe a major resonant mode with unusual and strongly anisotropic properties, which is not anticipated by the conventional theory of Goldstone spin waves. Lastly, we propose that this unexpected magnetic excitation can be attributed to a field-independent magnon mode renormalized due to its interaction with the high-energy amplitude (Higgs) mode in the regime of weak spontaneous symmetry breaking.

  18. Topological antiferromagnetic spintronics

    Science.gov (United States)

    Šmejkal, Libor; Mokrousov, Yuriy; Yan, Binghai; MacDonald, Allan H.

    2018-03-01

    The recent demonstrations of electrical manipulation and detection of antiferromagnetic spins have opened up a new chapter in the story of spintronics. Here, we review the emerging research field that is exploring the links between antiferromagnetic spintronics and topological structures in real and momentum space. Active topics include proposals to realize Majorana fermions in antiferromagnetic topological superconductors, to control topological protection and Dirac points by manipulating antiferromagnetic order parameters, and to exploit the anomalous and topological Hall effects of zero-net-moment antiferromagnets. We explain the basic concepts behind these proposals, and discuss potential applications of topological antiferromagnetic spintronics.

  19. Perspectives of antiferromagnetic spintronics

    Science.gov (United States)

    Jungfleisch, Matthias B.; Zhang, Wei; Hoffmann, Axel

    2018-04-01

    Antiferromagnets are promising for future spintronic applications owing to their advantageous properties: They are magnetically ordered, but neighboring magnetic moments point in opposite directions, which results in zero net magnetization. This means antiferromagnets produce no stray fields and are insensitive to external magnetic field perturbations. Furthermore, they show intrinsic high frequency dynamics, exhibit considerable spin-orbit and magneto-transport effects. Over the past decade, it has been realized that antiferromagnets have more to offer than just being utilized as passive components in exchange bias applications. This development resulted in a paradigm shift, which opens the pathway to novel concepts using antiferromagnets for spin-based technologies and applications. This article gives a broad perspective on antiferromagnetic spintronics. In particular, the manipulation and detection of antiferromagnetic states by spintronics effects, as well as spin transport and dynamics in antiferromagnetic materials will be discussed. We will also outline current challenges and future research directions in this emerging field.

  20. Thermal Transport and Magnetotransport Properties of CuCr1-xMgxO2 with a Spin-3/2 Antiferromagnetic Triangular Lattice

    Science.gov (United States)

    Okuda, Tetsuji; Oozono, Satoshi; Kihara, Takumi; Tokunaga, Masashi

    2013-01-01

    We have investigated the thermal conductivity (κ) and magnetoresistance (MR) of non-doped and hole-doped delafossite CuCrO2 with a spin-3/2 antiferromagnetic (AF) triangular sublattice. The phonon mean free path above the Néel temperature (TN) deduced from κ and lattice specific heat is almost identical to the magnetic correlation length, which indicates that, for both compounds, spin fluctuation enhanced in a geometrically frustrated lattice is strongly coupled with acoustic phonon above TN. κ below TN is significantly suppressed by Mg substitution, suggesting the introduction of some disorder into the 120° Néel state. For the hole-doped CuCr0.97Mg0.03O2, a negative MR is observed above TN, which is enhanced with a decrease in T toward TN, while a component of positive MR appears below TN and the residual negative MR component is observed in a high magnetic field, indicating that spin fluctuation coupled with electrical conductivity is critically enhanced above TN and remains below TN. These results evidence that the 120° Néel state is partially disordered by a doped itinerant hole coupled with spin fluctuation, although AF transition is certainly promoted. The dynamic partial disorder may stabilize the Néel order through an order-by-disorder mechanism.

  1. Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compound N a2C o2Te O6

    Science.gov (United States)

    Bera, A. K.; Yusuf, S. M.; Kumar, Amit; Ritter, C.

    2017-03-01

    The crystal structure, magnetic ground state, and the temperature-dependent microscopic spin-spin correlations of the frustrated honeycomb lattice antiferromagnet N a2C o2Te O6 have been investigated by powder neutron diffraction. A long-range antiferromagnetic (AFM) ordering has been found below TN˜24.8 K . The magnetic ground state, determined to be zigzag antiferromagnetic and characterized by a propagation vector k =(1 /2 0 0 ) , occurs due to the competing exchange interactions up to third-nearest neighbors within the honeycomb lattice. The exceptional existence of a limited magnetic correlation length along the c axis (perpendicular to the honeycomb layers in the a b planes) has been found even at 1.8 K, well below the TN˜24.8 K . The observed limited correlation along the c axis is explained by the disorder distribution of the Na ions within the intermediate layers between honeycomb planes. The reduced ordered moments mCo (1 )=2.77 (3 ) μB/C o2 + and mCo (2 )=2.45 (2 ) μB/C o2 + at 1.8 K reflect the persistence of spin fluctuations in the ordered state. Above TN˜24.8 K , the presence of short-range magnetic correlations, manifested by broad diffuse magnetic peaks in the diffraction patterns, has been found. Reverse Monte Carlo analysis of the experimental diffuse magnetic scattering data reveals that the spin correlations are mainly confined within the two-dimensional honeycomb layers (a b plane) with a correlation length of ˜12 Å at 25 K. The nature of the spin arrangements is found to be similar in both the short-range and long-range ordered magnetic states. This implies that the short-range correlation grows with decreasing temperature and leads to the zigzag AFM ordering at T ≤TN . The present study provides a comprehensive picture of the magnetic correlations over the temperature range above and below the TN and their relation to the crystal structure. The role of intermediate soft Na layers on the magnetic coupling between honeycomb planes is

  2. Observation of spatial charge and spin correlations in the 2D Fermi-Hubbard model.

    Science.gov (United States)

    Cheuk, Lawrence W; Nichols, Matthew A; Lawrence, Katherine R; Okan, Melih; Zhang, Hao; Khatami, Ehsan; Trivedi, Nandini; Paiva, Thereza; Rigol, Marcos; Zwierlein, Martin W

    2016-09-16

    Strong electron correlations lie at the origin of high-temperature superconductivity. Its essence is believed to be captured by the Fermi-Hubbard model of repulsively interacting fermions on a lattice. Here we report on the site-resolved observation of charge and spin correlations in the two-dimensional (2D) Fermi-Hubbard model realized with ultracold atoms. Antiferromagnetic spin correlations are maximal at half-filling and weaken monotonically upon doping. At large doping, nearest-neighbor correlations between singly charged sites are negative, revealing the formation of a correlation hole, the suppressed probability of finding two fermions near each other. As the doping is reduced, the correlations become positive, signaling strong bunching of doublons and holes, in agreement with numerical calculations. The dynamics of the doublon-hole correlations should play an important role for transport in the Fermi-Hubbard model. Copyright © 2016, American Association for the Advancement of Science.

  3. Studies of diluted antiferromagnets MnxMg1-xTiO3 with x=0.55 and 0.70 by muon spin relaxation method

    International Nuclear Information System (INIS)

    Fukaya, A.; Ito, A.; Torikai, E.; Nishiyama, K.; Nagamine, K.

    1997-01-01

    Longitudinal fields μSR measurements have been performed in order to probe the spin dynamics in the diluted antiferromagnets Mn x Mg 1-x TiO 3 with x=0.70 and 0.55. In the x=0.70 sample which forms the antiferromagnetic long-range order, the static and fluctuating fields coexist at the muon stopping site below T N . On the other hand, in the x=0.55 sample which shows the spin-glass behavior, the local fields fluctuate rather fast even below T SG . We infer that this drastic change occurs when Mn x Mg 1-x TiO 3 transforms from an antiferromagnetic system to a spin-glass system by dilution

  4. Low temperature magnetic properties and spin dynamics in single crystals of Cr{sub 8}Zn antiferromagnetic molecular rings

    Energy Technology Data Exchange (ETDEWEB)

    Adelnia, Fatemeh [Dipartimento di Fisica, Università degli Studi di Milano and INSTM, I-20133 Milano (Italy); Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, I-27100 Pavia (Italy); Chiesa, Alessandro; Bordignon, Sara; Carretta, Stefano [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, I-43124 Parma (Italy); Ghirri, Alberto; Candini, Andrea [CNR Institute Nanosciences S3, I- 41125 Modena (Italy); Cervetti, Christian [Dipartimento di Scienze Fisiche, Informatiche, Matematiche, Università di Modena e Reggio Emilia, I-41125 Modena (Italy); Evangelisti, Marco [CNR Institute Nanosciences S3, I- 41125 Modena (Italy); Dipartimento di Scienze Fisiche, Informatiche, Matematiche, Università di Modena e Reggio Emilia, I-41125 Modena (Italy); Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Affronte, Marco [CNR Institute Nanosciences S3, I- 41125 Modena (Italy); Dipartimento di Scienze Fisiche, Informatiche, Matematiche, Università di Modena e Reggio Emilia, I-41125 Modena (Italy); Sheikin, Ilya [Grenoble High Magnetic Field Laboratory, CNRS-LNCMI, 25, B.P. 166, 38042 Grenoble Cedex 9 (France); Winpenny, Richard; Timco, Grigore [The Lewis Magnetism Laboratory, The University of Manchester, M13 9PL Manchester (United Kingdom); Borsa, Ferdinando [Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, I-27100 Pavia (Italy); and others

    2015-12-28

    A detailed experimental investigation of the effects giving rise to the magnetic energy level structure in the vicinity of the level crossing (LC) at low temperature is reported for the open antiferromagnetic molecular ring Cr{sub 8}Zn. The study is conducted by means of thermodynamic techniques (torque magnetometry, magnetization and specific heat measurements) and microscopic techniques (nuclear magnetic resonance line width, nuclear spin lattice, and spin-spin relaxation measurements). The experimental results are shown to be in excellent agreement with theoretical calculations based on a minimal spin model Hamiltonian, which includes a Dzyaloshinskii-Moriya interaction. The first ground state level crossing at μ{sub 0}H{sub c1} = 2.15 T is found to be an almost true LC while the second LC at μ{sub 0}H{sub c2} = 6.95 T has an anti-crossing gap of Δ{sub 12} = 0.19 K. In addition, both NMR and specific heat measurements show the presence of a level anti-crossing between excited states at μ{sub 0}H = 4.5 T as predicted by the theory. In all cases, the fit of the experimental data is improved by introducing a distribution of the isotropic exchange couplings (J), i.e., using a J strain model. The peaks at the first and second LCs in the nuclear spin-lattice relaxation rate are dominated by inelastic scattering and a value of Γ ∼ 10{sup 10} rad/s is inferred for the life time broadening of the excited state of the open ring, due to spin phonon interaction. A loss of NMR signal (wipe-out effect) is observed for the first time at LC and is explained by the enhancement of the spin-spin relaxation rate due to the inelastic scattering.

  5. Single reference Coupled Cluster treatment of nearly degenerate problems: Cohesive energy of antiferromagnetic lattices of spin 1 centers

    International Nuclear Information System (INIS)

    Malrieu, Jean-Paul

    2012-01-01

    Lattices of antiferromagnetically coupled spins, ruled by Heisenberg Hamiltonians, are intrinsically highly degenerate systems. The present work tries to estimate the ground state energy of regular bipartite spin lattices of S = 1 sites from a single reference Coupled Cluster expansion starting from a Néel function, taken as reference. The simultaneous changes of spin momentum on adjacent sites play the role of the double excitations in molecular electronic problems. Propagation of the spin changes plays the same role as the triple excitations. The treatment takes care of the deviation of multiple excitation energies from additivity. Specific difficulties appear for 1D chains, which are not due to a near degeneracy between the reference and the vectors which directly interact with it but to the complexity of the processes which lead to the low energy configurations where a consistent reversed-Néel domain is created inside the Néel starting spin wave. Despite these difficulties a reasonable value of the cohesive energy is obtained.

  6. Single reference Coupled Cluster treatment of nearly degenerate problems: Cohesive energy of antiferromagnetic lattices of spin 1 centers

    Science.gov (United States)

    Malrieu, Jean-Paul

    2012-06-01

    Lattices of antiferromagnetically coupled spins, ruled by Heisenberg Hamiltonians, are intrinsically highly degenerate systems. The present work tries to estimate the ground state energy of regular bipartite spin lattices of S = 1 sites from a single reference Coupled Cluster expansion starting from a Néel function, taken as reference. The simultaneous changes of spin momentum on adjacent sites play the role of the double excitations in molecular electronic problems. Propagation of the spin changes plays the same role as the triple excitations. The treatment takes care of the deviation of multiple excitation energies from additivity. Specific difficulties appear for 1D chains, which are not due to a near degeneracy between the reference and the vectors which directly interact with it but to the complexity of the processes which lead to the low energy configurations where a consistent reversed-Néel domain is created inside the Néel starting spin wave. Despite these difficulties a reasonable value of the cohesive energy is obtained.

  7. Neutron scattering studies of two-dimensional antiferromagnetic spin fluctuations in insulating and superconducting S = 1/2 systems

    Energy Technology Data Exchange (ETDEWEB)

    Bech Christensen, N

    2005-01-01

    Time-of-flight and polarized triple axis neutron scattering is used to probe the spin excitations of Cu(DCOO){sub 2}x4D{sub 2}O and La{sub 2-x}Sr{sub x}CuO{sub 4}. The first part of the thesis contains an investigation of the excitation spectrum of the square lattice S = 1/2 Heisenberg antiferromagnet Cu(DCOO){sub 2}4D{sub 2}O. Along the antiferromagnetic zone boundary a pronounced intensity variation is found for the dominant single-magnon excitations. This variation tracks an already known zone boundary dispersion. Using polarization analysis to separate the components of the excitation spectrum, a continuum of longitudinally polarized multimagnon excitations is discovered at energies above the single-magnon branch. At low energies, the findings are well described by linear spin wave theory. At high energies, linear spin wave theory fails and instead the data are very well accounted for by state-of-the-art Quantum Monte Carlo computations. In the second part of the thesis, the spin excitation spectra of the high temperature superconductors La{sub 1.90}Sr{sub 0.10}CuO{sub 4} and La{sub 1.84}Sr{sub 0.16}Cu characterized. The main discovery is that the excitations are dispersive at both doping levels. The dispersion strongly resembles that seen in other high-T{sub c} superconductors. The presence of dispersive excitations does not require superconductivity to exist. For La{sub 1.84}Sr{sub 0.16}CuO{sub 4}, but not for La{sub 1.90}Sr{sub 0.10}CuO{sub 4}, the onset superconductivity gives rise to a spectral weight shift which displays qualitative and quantitative similarities to the resonance mode observed in other high-T{sub c} superconductors. (au)

  8. Investigation of the spin-1 honeycomb antiferromagnet BaNi2V2O8 with easy-plane anisotropy

    Science.gov (United States)

    Klyushina, E. S.; Lake, B.; Islam, A. T. M. N.; Park, J. T.; Schneidewind, A.; Guidi, T.; Goremychkin, E. A.; Klemke, B.; Mânsson, M.

    2017-12-01

    The magnetic properties of the two-dimensional, S =1 honeycomb antiferromagnet BaNi2V2O8 have been comprehensively studied using dc susceptibility measurements and inelastic neutron scattering techniques. The magnetic excitation spectrum is found to be dispersionless within experimental resolution between the honeycomb layers, while it disperses strongly within the honeycomb plane where it consists of two gapped spin-wave modes. The magnetic excitations are compared to linear spin-wave theory allowing the Hamiltonian to be determined. The first- and second-neighbor magnetic exchange interactions are antiferromagnetic and lie within the ranges 10.90 meV ≤Jn≤13.35 meV and 0.85 meV ≤Jn n≤1.65 meV, respectively. The interplane coupling Jout is four orders of magnitude weaker than the intraplane interactions, confirming the highly two-dimensional magnetic behavior of this compound. The sizes of the energy gaps are used to extract the magnetic anisotropies and reveal substantial easy-plane anisotropy and a very weak in-plane easy-axis anisotropy. Together these results reveal that BaNi2V2O8 is a candidate compound for the investigation of vortex excitations and Berezinsky-Kosterliz-Thouless phenomenon.

  9. Neutron scattering studies of two-dimensional antiferromagnetic spin fluctuations in insulating and superconducting S = ½ systems

    DEFF Research Database (Denmark)

    Christensen, Niels Bech

    Time-of-flight and polarized triple axis neutron scattering is used to probe the spin excitations of Cu(DCOO)_2_·_4D_2O and La_2_-_xSr_xCuO_4. The first part of the thesis contains an investigation of the excitation spectrum of the square lattice S = 1/2Heisenberg antiferromagnet Cu(DCOO)_2_·_4D_2O....... Along the antiferromagnetic zone boundary a pronounced intensity variation is found for the dominant single-magnon excitations. This variation tracks an already known zone boundary dispersion. Usingpolarization analysis to separate the components of the excitation spectrum, a continuum of longitudinally...... computations. In the second part of the thesis, the spin excitation spectra of the hightemperature superconductors La_1_._9_0Sr_0_._1_0CuO_4 and La_1_._8_4Sr_0_._1_6CuO_4 are characterized. The main discovery is that the excitations are dispersive at both doping levels. The dispersion strongly resembles...

  10. Perspectives of Antiferromagnetic Spintronics

    Energy Technology Data Exchange (ETDEWEB)

    Jungfleisch, Matthias B.; Zhang, Wei; Hoffmann, Axel

    2018-04-05

    Antiferromagnets are promising for future spintronics applications owing to their interesting properties: They are magnetically ordered, but neighboring magnetic moments point in opposite directions which results in zero net magneti- zation. This means antiferromagnets produce no stray fields and are insensitive to external magnetic field perturbations. Furthermore, they show intrinsic high frequency dynamics, exhibit considerable spin-orbit and magneto-transport effects. Over the past decade, it has been realized that antiferromagnets have more to offer than just being utilized as passive components in exchange bias applications. This development resulted in a paradigm shift, which opens the pathway to novel concepts using antiferromagnets for spin-based technologies and applications. This article gives a broad per- spective on antiferromagnetic spintronics. In particular, the manipulation and detection of anitferromagnetic states by spintronics effects, as well as spin transport and dynamics in antiferromagnetic materials will be discussed. We will also outline current challenges and future research directions in this emerging field.

  11. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    Taking the case of = 1, we show that the `non-oriented' nature and hence squeezing arise from the intrinsic quantum correlations that exist among the ... Department of Studies in Physics, University of Mysore, Mysore 570 006, India; Department of Physics, Yuvaraja's College, University of Mysore, Mysore 570 005, India ...

  12. Density of states and phase diagram of the antiferromagnetic spin chain with Dzyaloshinsky-Moriya interaction and spin-phonon coupling

    International Nuclear Information System (INIS)

    Wang Qin; Chen Hong; Zheng Hang

    2007-01-01

    The effects of DM interaction on the density-of-states, the dimerization and the phase diagram in the antiferromagnetic Heisenberg chain coupled with quantum phonons have been studied by a nonadiabatic analytical approach. The results show that the effect of the DM interaction is to increase the staggered antisymmetric spin exchange interaction order but to decrease the spin dimerization and their competitions result in the lattice dimerization ordering parameter to increase for large staggered DM interaction parameter β and decrease for small β. A crossover of β exists in which the dimerization ordering parameter changes non-monotonously. As the DM interaction parameter D increases, depending on the appropriate values of spin-phonon coupling, phonon frequency and β, the system undergoes phase transition from spin gapless state to gapped state or reversely and can even reenter between the two states. The relation between the phonon-staggered ordering parameter, the spin-dimer order parameter and the staggered DM interaction order parameter gives clearly their contributing weights to the lattice dimerization

  13. Spin Liquid State in the 3D Frustrated Antiferromagnet PbCuTe_{2}O_{6}: NMR and Muon Spin Relaxation Studies.

    Science.gov (United States)

    Khuntia, P; Bert, F; Mendels, P; Koteswararao, B; Mahajan, A V; Baenitz, M; Chou, F C; Baines, C; Amato, A; Furukawa, Y

    2016-03-11

    PbCuTe_{2}O_{6} is a rare example of a spin liquid candidate featuring a three-dimensional magnetic lattice. Strong geometric frustration arises from the dominant antiferromagnetic interaction that generates a hyperkagome network of Cu^{2+} ions although additional interactions enhance the magnetic lattice connectivity. Through a combination of magnetization measurements and local probe investigations by NMR and muon spin relaxation down to 20 mK, we provide robust evidence for the absence of magnetic freezing in the ground state. The local spin susceptibility probed by the NMR shift hardly deviates from the macroscopic one down to 1 K pointing to a homogeneous magnetic system with a low defect concentration. The saturation of the NMR shift and the sublinear power law temperature (T) evolution of the 1/T_{1} NMR relaxation rate at low T point to a nonsinglet ground state favoring a gapless fermionic description of the magnetic excitations. Below 1 K a pronounced slowing down of the spin dynamics is witnessed, which may signal a reconstruction of spinon Fermi surface. Nonetheless, the compound remains in a fluctuating spin liquid state down to the lowest temperature of the present investigation.

  14. Gapped paramagnetic state in a frustrated spin-1/2 Heisenberg antiferromagnet on the cross-striped square lattice

    Science.gov (United States)

    Li, P. H. Y.; Bishop, R. F.

    2018-03-01

    We implement the coupled cluster method to very high orders of approximation to study the spin-1/2 J1 -J2 Heisenberg model on a cross-striped square lattice. Every nearest-neighbour pair of sites on the square lattice has an isotropic antiferromagnetic exchange bond of strength J1 > 0 , while the basic square plaquettes in alternate columns have either both or neither next-nearest-neighbour (diagonal) pairs of sites connected by an equivalent frustrating bond of strength J2 ≡ αJ1 > 0 . By studying the magnetic order parameter (i.e., the average local on-site magnetization) in the range 0 ≤ α ≤ 1 of the frustration parameter we find that the quasiclassical antiferromagnetic Néel and (so-called) double Néel states form the stable ground-state phases in the respective regions α α1bc = 0.615(5) . The double Néel state has Néel (⋯ ↑↓↑↓ ⋯) ordering along the (column) direction parallel to the stripes of squares with both or no J2 bonds, and spins alternating in a pairwise (⋯ ↑↑↓↓↑↑↓↓ ⋯) fashion along the perpendicular (row) direction, so that the parallel pairs occur on squares with both J2 bonds present. Further explicit calculations of both the triplet spin gap and the zero-field uniform transverse magnetic susceptibility provide compelling evidence that the ground-state phase over all or most of the intermediate regime α1ac state with no discernible long-range magnetic order.

  15. The anisotropic quantum spin-1/2 Heisenberg antiferromagnet in the presence of a longitudinal field on a bcc lattice

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Minos A., E-mail: minos@pq.cnpq.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); Roberto Viana, J., E-mail: vianafisica@bol.com.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); Ricardo de Sousa, J., E-mail: jsousa@edu.ufam.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); National Institute of Science and Technology for Complex Systems, 3000, Japiim, Manaus, 69077-000 AM (Brazil)

    2012-08-15

    In this work we study the critical behavior of the quantum spin-1/2 anisotropic Heisenberg antiferromagnet in the presence of a longitudinal field on a body centered cubic (bcc) lattice as a function of temperature, anisotropy parameter ({Delta}) and magnetic field (H), where {Delta}=0 and 1 correspond the isotropic Heisenberg and Ising models, respectively. We use the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). The staggered m{sub s}=(m{sub A}-m{sub B})/2 and total m=(m{sub A}+m{sub B})/2 magnetizations are numerically calculated, where in the limit of m{sub s}{yields}0 the critical line T{sub N}(H,{Delta}) is obtained. The phase diagram in the T-H plane is discussed as a function of the parameter {Delta} for all values of H Element-Of [0,H{sub c}({Delta})], where H{sub c}({Delta}) correspond the critical field (T{sub N}=0). Special focus is given in the low temperature region, where a reentrant behavior is observed around of H=H{sub c}({Delta}){>=}H{sub c}({Delta}=1)=8J in the Ising limit, results in accordance with Monte Carlo simulation, and also was observed for all values of {Delta} Element-Of [0,1]. This reentrant behavior increases with increase of the anisotropy parameter {Delta}. In the limit of low field, our results for the Heisenberg limit are compared with series expansion values. - Highlights: Black-Right-Pointing-Pointer In the lat decade there has been a great interest in the physics of the quantum phase transition in spins system. Black-Right-Pointing-Pointer Effective-field theory in cluster with N=4 spins is generalized to treat the quantum spin-1/2 Heisenberg model. Black-Right-Pointing-Pointer We have obtained phase diagram at finite temperature for the quantum spin-1/2 antiferromagnet Heisenberg model as a bcc lattice.

  16. Weakly spin-dependent band structures of antiferromagnetic perovskite LaMO3(M  =  Cr, Mn, Fe).

    Science.gov (United States)

    Okugawa, Takuya; Ohno, Kaoru; Noda, Yusuke; Nakamura, Shinichiro

    2018-02-21

    We investigate the spin-dependent electronic states of antiferromagnetic (AFM) lanthanum chromite (LaCrO 3 ), lanthanum manganite (LaMnO 3 ), and lanthanum ferrite (LaFeO 3 ) using spin-polarized first-principles density functional theory with Hubbard U correction. The band structures are calculated for 15 types of their different AFM structures. It is verified for these structures that there is a very simple rule to identify which wave number [Formula: see text] exhibits spin splitting or degeneracy in the band structure. This rule uses the symmetry operations that map the up-spin atoms onto the down-spin atoms. The resulting spin splitting is very small for the most stable spin configuration of the most stable experimental structure. We discuss a plausible benefit of this characteristic, i.e. the direction-independence of the spin current, in electrode applications.

  17. Spin-orbit torques in locally and globally noncentrosymmetric crystals: antiferromagnets and ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Železný, Jakub; Gao, H.; Manchon, A.; Freimuth, F.; Mokrousov, Y.; Zemen, J.; Mašek, Jan; Sinova, Jairo; Jungwirth, Tomáš

    2017-01-01

    Roč. 95, č. 1 (2017), 1-18, č. článku 014403. ISSN 2469-9950 R&D Projects: GA MŠk LM2015087; GA ČR GB14-37427G; GA MŠk(CZ) LM2011026 EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.836, year: 2016

  18. High antiferromagnetic domain wall velocity induced by Néel spin-orbit torques

    Czech Academy of Sciences Publication Activity Database

    Gomonay, O.; Jungwirth, Tomáš; Sinova, Jairo

    2016-01-01

    Roč. 117, č. 1 (2016), 1-5, č. článku 017202. ISSN 0031-9007 R&D Projects: GA MŠk(CZ) LM2011026; GA ČR GB14-37427G EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : spintronics * domain walls * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.462, year: 2016

  19. Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films

    Czech Academy of Sciences Publication Activity Database

    Wadley, P.; Edmonds, K. W.; Shahedkhah, M.R.; Campion, R. P.; Gallagher, B. L.; Železný, Jakub; Kuneš, Jan; Novák, Vít; Jungwirth, Tomáš; Saidl, Vít; Němec, P.; Maccherozzi, F.; Dhesi, S.S.

    2017-01-01

    Roč. 7, Sep (2017), 1-6, č. článku 11147. ISSN 2045-2322 R&D Projects: GA MŠk LM2015087; GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : antiferromagnetic spintronics * exchange coupling Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  20. Magnetic Spin Correlations in the One-dimensional Frustrated Spin-chain System Ca3Co2O6

    Science.gov (United States)

    Månsson, M.; Sugiyama, J.; Roessli, B.; Hitti, B.; Ikedo, Y.; Zivkovic, I.; Nozaki, H.; Harada, M.; Sassa, Y.; Andreica, D.; Goko, T.; Amato, A.; Ofer, O.; Ansaldo, E. J.; Brewer, J. H.; Chow, K. H.; Yi, H. T.; Cheong, S.-W.; Prsa, K.

    In this work we present a combination of zero-field and high transverse-field muon spin rotation/relaxation (μ+SR) measurements. The current μ+SR Knight-shift measurements clearly shows that Ca3Co2O6 display strong spin correlations even at room-temperature. Further, several anomalies in the temperature dependent data are proposed to be connected to the onset of a quasi-one-dimensional (Q1D) ferrimagnetic order. Further, we suggest that in the low-temperature regime, the Q1D ferrimagnetic order co-exist within a long-range antiferromagnetic phase, which has been confirmed by our recent neutron scattering studies.

  1. Characterisation of spin-waves in copper(II) deuteroformate tetradeuterate: A square ¤S¤=1/2 Heisenberg antiferromagnet

    DEFF Research Database (Denmark)

    Clarke, S.J.; Harrison, A.; Mason, T.E.

    1999-01-01

    Copper(II) formate tetrahydrate (CFTH) is a model square S = 1/2 Heisenberg antiferromagnet with T-N = 16.54 +/- 0.05 K. The dispersion of spin-waves in the magnetic layers of a fully deuterated sample of this material has been mapped at 4.3 K by inelastic neutron scattering from the zone centre...

  2. Erratum : Critical Properties of Spin-1 Antiferromagnetic Heisenberg Chains with Bond Alternation and Uniaxial Single-Ion-Type Anisotropy (vol 69, pg 237, 2000)

    OpenAIRE

    Chen, Wei; 飛田, 和男; Sanctuary, Bryan C.

    2008-01-01

    Original Paper :Critical Properties of Spin-1 Antiferromagnetic Heisenberg Chains with Bond Alternation and Uniaxial Single-Ion-Type AnisotropyWei Chen, Kazuo Hida and Bryan Clifford Sanctuary Journal of the Physical Society of Japan 69 (2000) pp.237-241

  3. Magnetization process and magnetocaloric effect in geometrically frustrated Ising antiferromagnet and spin ice models on a 'Star of David' nanocluster

    Science.gov (United States)

    Žukovič, M.; Semjan, M.

    2018-04-01

    Magnetic and magnetocaloric properties of geometrically frustrated antiferromagnetic Ising (IA) and ferromagnetic spin ice (SI) models on a nanocluster with a 'Star of David' topology, including next-nearest-neighbor (NNN) interactions, are studied by an exact enumeration. In an external field applied in characteristic directions of the respective models, depending on the NNN interaction sign and magnitude, the ground state magnetization of the IA model is found to display up to three intermediate plateaus at fractional values of the saturation magnetization, while the SI model shows only one zero-magnetization plateau and only for the antiferromagnetic NNN coupling. A giant magnetocaloric effect is revealed in the IA model with the NNN interaction either absent or equal to the nearest-neighbor coupling. The latter is characterized by abrupt isothermal entropy changes at low temperatures and infinitely fast adiabatic temperature variations for specific entropy values in the processes when the magnetic field either vanishes or tends to the critical values related to the magnetization jumps.

  4. Spin frustration and magnetic ordering in triangular lattice antiferromagnet Ca3CoNb2O9

    Science.gov (United States)

    Dai, Jia; Zhou, Ping; Wang, Peng-Shuai; Pang, Fei; Munsie, Tim J.; Luke, Graeme M.; Zhang, Jin-Shan; Yu, Wei-Qiang

    2015-12-01

    We synthesized a quasi-two-dimensional distorted triangular lattice antiferromagnet Ca3CoNb2O9, in which the effective spin of Co2+ is 1/2 at low temperatures, whose magnetic properties were studied by dc susceptibility and magnetization techniques. The x-ray diffraction confirms the quality of our powder samples. The large Weiss constant θCW˜ -55 K and the low Neel temperature TN˜ 1.45 K give a frustration factor f = | θCW/TN | ≈ 38, suggesting that Ca3CoNb2O9 resides in strong frustration regime. Slightly below TN, deviation between the susceptibility data under zero-field cooling (ZFC) and field cooling (FC) is observed. A new magnetic state with 1/3 of the saturate magnetization Ms is suggested in the magnetization curve at 0.46 K. Our study indicates that Ca3CoNb2O9 is an interesting material to investigate magnetism in triangular lattice antiferromagnets with weak anisotropy. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374364 and 11222433), the National Basic Research Program of China (Grant No. 2011CBA00112). Research at McMaster University supported by the Natural Sciences and Engineering Research Council. Work at North China Electric Power University supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

  5. Fullerene/layered antiferromagnetic reconstructed spinterface: Subsurface layer dominates molecular orbitals' spin-split and large induced magnetic moment

    Science.gov (United States)

    Shao, Yangfan; Pang, Rui; Pan, Hui; Shi, Xingqiang

    2018-03-01

    The interfaces between organic molecules and magnetic metals have gained increasing interest for both fundamental reasons and applications. Among them, the C60/layered antiferromagnetic (AFM) interfaces have been studied only for C60 bonded to the outermost ferromagnetic layer [S. L. Kawahara et al., Nano Lett. 12, 4558 (2012) and D. Li et al., Phys. Rev. B 93, 085425 (2016)]. Here, via density functional theory calculations combined with evidence from the literature, we demonstrate that C60 adsorption can reconstruct the layered-AFM Cr(001) surface at elevated annealing temperatures so that C60 bonds to both the outermost and the subsurface Cr layers in opposite spin directions. Surface reconstruction drastically changes the adsorbed molecule spintronic properties: (1) the spin-split p-d hybridization involves multi-orbitals of C60 and top two layers of Cr with opposite spin-polarization, (2) the subsurface Cr atom dominates the C60 electronic properties, and (3) the reconstruction induces a large magnetic moment of 0.58 μB in C60 as a synergistic effect of the top two Cr layers. The induced magnetic moment in C60 can be explained by the magnetic direct-exchange mechanism, which can be generalized to other C60/magnetic metal systems. Understanding these complex hybridization behaviors is a crucial step for molecular spintronic applications.

  6. Reduced interface spin polarization by antiferromagnetically coupled Mn segregated to the C o2MnSi /GaAs (001) interface

    Science.gov (United States)

    Rath, Ashutosh; Sivakumar, Chockalingam; Sun, C.; Patel, Sahil J.; Jeong, Jong Seok; Feng, J.; Stecklein, G.; Crowell, Paul A.; Palmstrøm, Chris J.; Butler, William H.; Voyles, Paul M.

    2018-01-01

    We have investigated the interfacial structure and its correlation with the calculated spin polarization in C o2MnSi /GaAs(001) lateral spin valves. C o2MnSi (CMS) films were grown on As-terminated c(4 ×4 ) GaAs(100) by molecular beam epitaxy using different first atomic layers: MnSi, Co, and Mn. Atomically resolved Z -contrast scanning transmission electron microscopy (STEM) imaging and electron energy loss spectroscopy (EELS) were used to develop atomic structural models of the CMS/GaAs interfaces that were used as inputs for first-principles calculations to understand the magnetic and electronic properties of the interface. First-principles structures were relaxed and then validated by comparing experimental and simulated high-resolution STEM images. STEM-EELS results show that all three films have similar six atomic layer thick, Mn- and As-rich multilayer interfaces. However, the Co-initiated interface contains a M n2As -like layer, which is antiferromagnetic, and which is not present in the other two interfaces. Density functional theory calculations show a higher degree of interface spin polarization in the Mn- and MnSi-initiated cases, compared to the Co-initiated case, although none of the interfaces are half-metallic. The loss of half-metallicity is attributed, at least in part, to the segregation of Mn at the interface, which leads to the formation of interface states. The implications for the performance of lateral spin valves based on these interfaces are discussed briefly.

  7. Mechanism of Basal-Plane Antiferromagnetism in the Spin-Orbit Driven Iridate Ba_{2}IrO_{4}

    Directory of Open Access Journals (Sweden)

    Vamshi M. Katukuri

    2014-06-01

    Full Text Available By ab initio many-body quantum chemistry calculations, we determine the strength of the symmetric anisotropy in the 5d^{5} j≈1/2 layered material Ba_{2}IrO_{4}. While the calculated anisotropic couplings come out in the range of a few meV, orders of magnitude stronger than in analogous 3d transition-metal compounds, the Heisenberg superexchange still defines the largest energy scale. The ab initio results reveal that individual layers of Ba_{2}IrO_{4} provide a close realization of the quantum spin-1/2 Heisenberg-compass model on the square lattice. We show that the experimentally observed basal-plane antiferromagnetism can be accounted for by including additional interlayer interactions and the associated order-by-disorder quantum-mechanical effects, in analogy to undoped layered cuprates.

  8. Writing and reading antiferromagnetic Mn2Au by Néel spin-orbit torques and large anisotropic magnetoresistance.

    Science.gov (United States)

    Bodnar, S Yu; Šmejkal, L; Turek, I; Jungwirth, T; Gomonay, O; Sinova, J; Sapozhnik, A A; Elmers, H-J; Kläui, M; Jourdan, M

    2018-01-24

    Using antiferromagnets as active elements in spintronics requires the ability to manipulate and read-out the Néel vector orientation. Here we demonstrate for Mn 2 Au, a good conductor with a high ordering temperature suitable for applications, reproducible switching using current pulse generated bulk spin-orbit torques and read-out by magnetoresistance measurements. Reversible and consistent changes of the longitudinal resistance and planar Hall voltage of star-patterned epitaxial Mn 2 Au(001) thin films were generated by pulse current densities of ≃10 7  A/cm 2 . The symmetry of the torques agrees with theoretical predictions and a large read-out magnetoresistance effect of more than ≃6% is reproduced by ab initio transport calculations.

  9. Magnetic Raman Scattering in Two-Dimensional Spin-1/2 Heisenberg Antiferromagnets: Explanation of the Spectral Shape Anomaly

    Science.gov (United States)

    Nori, F.; Merlin, R.; Haas, S.; Sandvick, A.; Dagotto, E.

    1996-03-01

    We calculate(F. Nori, R.Merlin, S. Haas, A.W. Sandvik, and E. Dagotto, Physical Review Letters) 75, 553 (1995). the Raman spectrum of the two-dimensional (2D) spin-1/2 Heisenberg antiferromagnet by exact diagonalization and quantum Monte Carlo techniques on clusters of up to 144 sites. On a 16-site cluster, we consider the phonon-magnon interaction which leads to random fluctuations of the exchange integral. Results are in good agreement with experiments on various high-Tc precursors, such as La_2CuO4 and YBa_2Cu_3O_6.2. In particular, our calculations reproduce the broad lineshape of the two-magnon peak, the asymmetry about its maximum, the existence of spectral weight at high energies, and the observation of nominally forbidden A_1g scattering.

  10. Electronic properties of antiferromagnetic UBi2 metal by exact exchange for correlated electrons method

    Directory of Open Access Journals (Sweden)

    E Ghasemikhah

    2012-03-01

    Full Text Available This study investigated the electronic properties of antiferromagnetic UBi2 metal by using ab initio calculations based on the density functional theory (DFT, employing the augmented plane waves plus local orbital method. We used the exact exchange for correlated electrons (EECE method to calculate the exchange-correlation energy under a variety of hybrid functionals. Electric field gradients (EFGs at the uranium site in UBi2 compound were calculated and compared with the experiment. The EFGs were predicted experimentally at the U site to be very small in this compound. The EFG calculated by the EECE functional are in agreement with the experiment. The densities of states (DOSs show that 5f U orbital is hybrided with the other orbitals. The plotted Fermi surfaces show that there are two kinds of charges on Fermi surface of this compound.

  11. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    OpenAIRE

    Zhang, Qiang; Tian, Wei; Peterson, Spencer G.; Dennis, Kevin W.; Vaknin, David

    2014-01-01

    Structure and magnetic properties of high-quality polycrystlline CeMnAsO, a parent compound of the "1111"-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. We find that CeMnAsO undergoes a C-type antiferromagnetic order with Mn$^{2+}$ ($S=5/2$) moments pointing along the \\textit{c}-axis below a relatively high N\\'{e}el temperature of $T_{\\rm N} = 345$ K. Below $T_{\\rm SR} = 35$ K, two instantaneous transitions occur where the Mn moments...

  12. Electric control of Dirac quasiparticles by spin-orbit torque in an antiferromagnet

    Czech Academy of Sciences Publication Activity Database

    Šmejkal, Libor; Železný, Jakub; Sinova, Jairo; Jungwirth, Tomáš

    2017-01-01

    Roč. 118, č. 10 (2017), 1-5, č. článku 106402. ISSN 0031-9007 R&D Projects: GA MŠk LM2015087; GA ČR GB14-37427G EU Projects: European Commission(XE) 610115 - SC2 Institutional support: RVO:68378271 Keywords : spintronics * topological Dirac fermions * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics , supercond.) Impact factor: 8.462, year: 2016

  13. Charge stripes and spin correlations in copper-oxide superconductors

    OpenAIRE

    Tranquada, J. M.

    1997-01-01

    Recent neutron diffraction studies have yielded evidence that, in a particular cuprate family, holes doped into the CuO(2) planes segregate into stripes that separate antiferromagnetic domains. Here it is shown that such a picture provides a quantitatively consistent interpretation of the spin fluctuations measured by neutron scattering in La(1.85)Sr(0.15)CuO(4) and YBa(2)Cu(3)O(6+x).

  14. Spin waves and phonons in a paraelectric antiferromagnet EuTiO3

    Science.gov (United States)

    Cao, Huibo; Hong, Jiawang; Delaire, Olivier; Hahn, Steven; Ehlers, Georg; Chi, Songxue; Garlea, Vasile; Fernandez-Baca, Jaime; Chakoumakos, Bryan; Yan, Jiaqiang; Sales, Brian

    2015-03-01

    Perovskite titanates ATiO3 (A=Ba,Pb,Sr,Ca,Cd,or Eu) are widely studied for their interesting instabilities and broad applications. A ferroelectric (FE) transition occurs in Ba, Pb, and Cd titanates, but not in SrTiO3 (STO) or EuTiO3 (ETO). In the case of STO, fluctuations yield a quantum paraelectric state, but whether ETO is quantum paraelectric remains an open question. Despite a number of similarities with well-studied STO, ETO is also unique owing to the magnetic Eu ions. By applying a tuning parameter, such as bi-axial tension, ETO can be turned into a FE ferromagnet, the ideal multiferroic. [J. H. Lee, et al., Nature 466, 954 (2010)] Studies of spin-spin and spin-lattice couplings in ETO are of great interest not only from a fundamental standpoint, but also for technological applications. We successfully grew a large, high-quality isotopically-enriched ETO crystal for neutron scattering. The crystal and magnetic structures were characterized with single crystal diffraction at HB-3A at HFIR at ORNL. The spin waves and phonons were measured in the temperature range of 1.5-400 K with CNCS at SNS and HB-3 at HFIR at ORNL. In this presentation, we will discuss structural instabilities, spin-spin interactions, and spin-phonon couplings in ETO. This work was supported by Office of Basic Energy Sciences, U.S. Department of Energy.

  15. Phase diagrams of antiferromagnetic spin-1 bosons on a square optical lattice with the quadratic Zeeman effect

    Science.gov (United States)

    de Forges de Parny, L.; Rousseau, V. G.

    2018-02-01

    We study the quadratic Zeeman effect (QZE) in a system of antiferromagnetic spin-1 bosons on a square lattice and derive the ground-state phase diagrams by means of quantum Monte Carlo simulations and mean-field treatment. The QZE imbalances the populations of the magnetic sublevels σ =±1 and σ =0 , and therefore affects the magnetic and mobility properties of the phases. Both methods show that the tip of the even Mott lobes, stabilized by singlet state, is destroyed when turning on the QZE, thus leaving the space to the superfluid phase. Contrariwise, the tips of odd Mott lobes remain unaffected. Therefore, the Mott-superfluid transition with even filling strongly depends on the strength of the QZE, and we show that the QZE can act as a control parameter for this transition at fixed hopping. Using quantum Monte Carlo simulations, we elucidate the nature of the phase transitions and examine in detail the nematic order: the first-order Mott-superfluid transition with even filling observed in the absence of QZE becomes second order for weak QZE, in contradistinction to our mean-field results which predict a first-order transition in a larger range of QZE. Furthermore, a spin nematic order with director along the z axis is found in the odd Mott lobes and in the superfluid phase for energetically favored σ =±1 states. In the superfluid phase with even filling, the x y components of the nematic director remain finite only for moderate QZE.

  16. Strong anisotropic anomalous Hall effect and spin Hall effect in the chiral antiferromagnetic compounds Mn3X (X =Ge , Sn, Ga, Ir, Rh, and Pt)

    Science.gov (United States)

    Zhang, Yang; Sun, Yan; Yang, Hao; Železný, Jakub; Parkin, Stuart P. P.; Felser, Claudia; Yan, Binghai

    2017-02-01

    We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds Mn3X (X = Ge, Sn, Ga, Ir, Rh and Pt) by ab initio band structure and Berry phase calculations. These studies reveal large and anisotropic values of both the intrinsic anomalous Hall effect and spin Hall effect. The Mn3X materials exhibit a noncollinear antiferromagnetic order which, to avoid geometrical frustration, forms planes of Mn moments that are arranged in a Kagome-type lattice. With respect to these Kagome planes, we find that both the anomalous Hall conductivity (AHC) and the spin Hall conductivity (SHC) are quite anisotropic for any of these materials. Based on our calculations, we propose how to maximize AHC and SHC for different materials. The band structures and corresponding electron filling, that we show are essential to determine the AHC and SHC, are compared for these different compounds. We point out that Mn3Ga shows a large SHC of about 600 (ℏ /e ) (Ωcm) -1 . Our work provides insights into the realization of strong anomalous Hall effects and spin Hall effects in chiral antiferromagnetic materials.

  17. Even-parity spin-triplet pairing by purely repulsive interactions for orbitally degenerate correlated fermions

    International Nuclear Information System (INIS)

    Zegrodnik, M; Bünemann, J; Spałek, J

    2014-01-01

    We demonstrate the stability of the spin-triplet paired s-wave (with an admixture of extended s-wave) state for the limit of purely repulsive interactions in a degenerate two-band Hubbard model of correlated fermions. The repulsive interactions limit represents an essential extension of our previous analysis (2013 New J. Phys. 15 073050), regarded here as I. We also show that near the half-filling the considered type of superconductivity can coexist with antiferromagnetism. The calculations have been carried out with the use of the so-called statistically consistent Gutzwiller approximation (SGA) for the case of a square lattice. We suggest that the electron correlations in conjunction with the Hund's rule exchange play the crucial role in stabilizing the real-space spin-triplet superconducting state. A sizable hybridization of the bands suppresses the homogeneous paired state. (paper)

  18. Critical and reentrant behavior of the spin quantum 1/2 anisotropic Heisenberg antiferromagnet model with Dzyaloshinskii–Moriya interaction in a longitudinal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Parente, Walter E.F.; Pacobahyba, J.T.M.; Araújo, Ijanílio G. [Departamento de Física, Universidade Federal de Roraima, BR 174, Km 12. Bairro Monte Cristo. CEP: 69300-000 Boa Vista, Roraima (Brazil); Neto, Minos A., E-mail: minos@pq.cnpq.br [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000, Manaus-AM (Brazil); Ricardo de Sousa, J. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000, Manaus-AM (Brazil); National Institute of Science and Technology for Complex Systems, 3000, Japiim, 69077-000, Manaus-AM (Brazil); Akinci, Ümit [Department of Physics, Dokuz Eylül University, Tr-35160 Izmir (Turkey)

    2014-04-15

    In this paper we study the quantum spin-1/2 anisotropic Heisenberg antiferromagnet model in the presence of a Dzyaloshinskii–Moriya interaction (D) and a uniform longitudinal (H) magnetic field. Using the effective-field theory with a finite cluster N=2 spin (EFT-2) we calculate the phase diagrams in the H−T and D−T planes on a simple cubic lattice (z=6). We have only observed second order phase transitions for values between Δ∈[0,1], where the cases were analysed: Ising (Δ=1), anisotropic Heisenberg (Δ=0.6) and isotropic Heisenberg (Δ=0). - Highlights: • Anisotropic Heisenberg antiferromagnet on a simple cubic lattice. • Effective-field theory. • Dzyaloshinskii–Moriya interaction.

  19. Spin model for nontrivial types of magnetic order in inverse-perovskite antiferromagnets

    Science.gov (United States)

    Mochizuki, Masahito; Kobayashi, Masaya; Okabe, Reoya; Yamamoto, Daisuke

    2018-02-01

    Nontrivial magnetic orders in the inverse-perovskite manganese nitrides are theoretically studied by constructing a classical spin model describing the magnetic anisotropy and frustrated exchange interactions inherent in specific crystal and electronic structures of these materials. With a replica-exchange Monte Carlo technique, a theoretical analysis of this model reproduces the experimentally observed triangular Γ5 g and Γ4 g spin-ordered patterns and the systematic evolution of magnetic orders. Our Rapid Communication solves a 40-year-old problem of nontrivial magnetism for the inverse-perovskite manganese nitrides and provides a firm basis for clarifying the magnetism-driven negative thermal expansion phenomenon discovered in this class of materials.

  20. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    International Nuclear Information System (INIS)

    Park, J.-S.; Lee, S.-R.; Kim, Y.K.

    2004-01-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field (H ex.eff ) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply

  1. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    Science.gov (United States)

    Park, Jeong-Suk; Lee, Seong-Rae; Kim, Young Keun

    2004-08-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field ( Hex.eff) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply.

  2. Low temperature ballistic spin transport in the S=1/2 antiferromagnetic Heisenberg chain compound SrCuO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maeter, H.; Klauss, H.H. [Institut fuer Festkoerperphysik, TU Dresden (Germany); Zvyagin, A.A. [Institut fuer Festkoerperphysik, TU Dresden (Germany); Institute for Low Temperature Physics and Engineering, NAS of Ukraine, Kharkov (Ukraine); Luetkens, H.; Pascua, G.; Shermadini, Z. [Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, Villigen (Switzerland); Hess, C.; Hlubek, N.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung, Dresden (Germany); Saint-Matin, R.; Revcolevschi, A. [Laboratoire de Physico-Chimie de L' Etat Solide, ICMMO, UMR 8182, Universite Paris-Sud, Orsay (France)

    2011-07-01

    For one-dimensional quantum spin chain systems recent experimental and theoretical studies indicate unexpectedly large, in some cases diverging spin and heat transport coefficients. Local probes, like e.g. muon spin relaxation ({mu}SR) can indirectly characterize the spin transport properties of low dimensional systems via the magnetic field dependence of the spin lattice relaxation rate {lambda}(B). For diffusive spin transport {lambda}{proportional_to}B{sup -0.5} is expected. For the ground state of the isotropic spin-1/2 antiferromagnetic Heisenberg chain the eigenstates of the Heisenberg Hamiltonian dominate the spin transport, which is then ballistic. Using the Mueller ansatz {lambda}{proportional_to}B{sup -1} is expected in this case. For SrCuO{sub 2} we find {lambda}{proportional_to}B{sup -0.9(3)}. This result is temperature independent for 5 K{<=}T {<=}300 K. Within conformal field theory and using the Mueller ansatz we conclude ballistic spin transport in SrCuO{sub 2}.

  3. Effect of spatial spin modulation on relaxation and NMR frequencies of sup 5 sup 7 Fe nuclei in ferroelectric antiferromagnetic BiFeO sub 3

    CERN Document Server

    Zalessky, A V; Zvezdin, A K; Gippius, A A; Morozova, E N; Khozeev, D F; Bush, A S; Pokatilov, V S

    2002-01-01

    The NMR spectra on the iron nuclei in the BiFeO sub 3 antiferromagnetic sample enriched by the sup 5 sup 7 Fe (95.43%) with the spatially-modulated magnetic structure are studied. It is established that the cycloid-type spin modulation in the BiFeO sub 3 produces spatial modulation of the nuclear spin-spin relaxation velocity and leads to the spectral nonuniform widening of the NMR local line. It is determined also that the local magnetic moments of the iron ions on various cycloid sections differently depend on temperature which testifies to different character of the spin waves excitation. The analogy of the experimental results with the NMR regularities in the Bloch wall is discussed

  4. Observation of layered antiferromagnetism in self-assembled parallel NiSi nanowire arrays on Si(110) by spin-polarized scanning tunneling spectromicroscopy

    Science.gov (United States)

    Hong, Ie-Hong; Hsu, Hsin-Zan

    2018-03-01

    The layered antiferromagnetism of parallel nanowire (NW) arrays self-assembled on Si(110) have been observed at room temperature by direct imaging of both the topographies and magnetic domains using spin-polarized scanning tunneling microscopy/spectroscopy (SP-STM/STS). The topographic STM images reveal that the self-assembled unidirectional and parallel NiSi NWs grow into the Si(110) substrate along the [\\bar{1}10] direction (i.e. the endotaxial growth) and exhibit multiple-layer growth. The spatially-resolved SP-STS maps show that these parallel NiSi NWs of different heights produce two opposite magnetic domains, depending on the heights of either even or odd layers in the layer stack of the NiSi NWs. This layer-wise antiferromagnetic structure can be attributed to an antiferromagnetic interlayer exchange coupling between the adjacent layers in the multiple-layer NiSi NW with a B2 (CsCl-type) crystal structure. Such an endotaxial heterostructure of parallel magnetic NiSi NW arrays with a layered antiferromagnetic ordering in Si(110) provides a new and important perspective for the development of novel Si-based spintronic nanodevices.

  5. Spin correlations in Ho2Ti2O7: A dipolar spin ice system

    DEFF Research Database (Denmark)

    Bramwell, S.T.; Harris, M.J.; Hertog, B.C. den

    2001-01-01

    described by a nearest neighbor spin ice model and very accurately described by a dipolar spin ice model. The heat capacity is well accounted for by the sum of a dipolar spin ice contribution and an expected nuclear spin contribution, known to exist in other Ho(3+) salts. These results settle the question......The pyrochlore material Ho(2)Ti(2)O(7) has been suggested to show "spin ice" behavior. We present neutron scattering and specific heat results that establish unambiguously that Ho(2)Ti(2)O(7) exhibits spin ice correlations at low temperature. Diffuse magnetic neutron scattering is quite well...

  6. Monte Carlo study of the two-dimensional spin-1/2 quantum Heisenberg model: Spin correlations in La2CuO4

    International Nuclear Information System (INIS)

    Manousakis, E.; Salvador, R.

    1989-01-01

    We study the spin-1/2 quantum ferromagnetic and antiferromagnetic Heisenberg model using Handscomb's Monte Carlo (MC) method on square lattices of various sizes. As the temperature is lowered the calculated correlation length in the antiferromagnetic case grows more rapidly than in the ferromagnetic case. We also obtain the correlation length in the leading order of the high-temperature series expansion which, at high temperatures, agrees very well with the MC results. The correlation length obtained from the MC calculation for the ferromagnetic and antiferromagnetic case is compared with existing theories. Taking the average value for the antiferromagnetic coupling between the values suggested by neutron- and Raman-scattering experiments done on La 2 CuO 4 , we compare our results for the correlation length with those observed by the neutron-scattering experiments. We find that our results for the correlation lengths away from the three-dimensional (3D) Neel temperature T/sub N/∼200 K are consistent with the experimental findings. In order to obtain agreement close to the Neel temperature, however, we need to introduce an interlayer coupling between the CuO 2 planes. The effect on a 3D coupling is only discussed in the framework of the quantum mechanical nonlinear σ model in three space dimensions. For the case of La 2 CuO 4 we find that close to T/sub N/ the σ model in 3+1 dimensions reduces to the classical 3D Heisenberg model whose critical properties are known and fit the neutron-scattering data for T∼T/sub N/

  7. Partially disordered state and spin-lattice coupling in an S=3/2 triangular lattice antiferromagnet Ag2CrO2

    Science.gov (United States)

    Matsuda, M.; Yoshida, H.; Isobe, M.; de La Cruz, C.; Fishman, R. S.

    2012-02-01

    Ag2CrO2 consists of triangular lattice planes of CrO2, which are well separated by the metallic Ag2 layers. [1] This compound is an S=3/2 frustrated triangular lattice antiferromagnet without orbital degree of freedom. We performed neutron diffraction experiments on a powder sample of Ag2CrO2 on a neutron powder diffractometer HB-2A and a triple-axis neutron spectrometer HB-1, installed at HFIR in Oak Ridge National Laboratory. With decreasing temperature, a short-range 4-sublatice spin state develops. However, a long-range partially disordered state with 5 sublattices abruptly appears at TN=24 K, accompanied by a structural distortion, and persists at least down to 2 K. The spin-lattice coupling stabilizes the anomalous state, which is expected to appear only in limited ranges of further-neighbor interactions and temperature. It was found that the spin-lattice coupling is a common feature in triangular lattice antiferromagnets with multiple-sublattice spin states, since the triangular lattice is elastic. [4pt] [1] H. Yoshida et al., to appear in J. Phys. Soc. Jpn.

  8. Quasi-2D J1-J2 antiferromagnet Zn2VO(PO4)2 and its Ti-substituted derivative: A spin-wave analysis

    Science.gov (United States)

    Kar, Satyaki; Saha-Dasgupta, Tanusri

    2014-01-01

    In this study, we present non-linear spin wave analysis of a quasi-2D spin-{1}/{2}J1-J2 antiferromagnet at the parameter regime relevant for the recently studied compound Zn2VO(PO4)2. We obtain the temperature dependence of the spin wave energy, susceptibility and magnetization using Green's function technique and Tyablikov's decoupling or Hartree-Fock factorization. The comparison of our numerical results with the experimental findings is discussed. Magnetic structure factor is calculated and compared with powder neutron diffraction data. We also study the spin wave behavior of the compound Zn2Ti0.25V0.75O(PO4)2 obtained by partial chemical substitution of Ti at V sites of the compound Zn2VO(PO4)2 [Kanungo, et al., Phys. Rev. B 87 (2013) 054431]. Due to the superlattice structure of the spin lattice, the substituted compound possesses multiple spin wave modes. The spin wave analysis confirms the quasi-1D nature of the substituted system.

  9. Spin-spin correlations of magnetic impurities in graphene

    OpenAIRE

    Guclu, A. D.; Bulut, Nejat

    2014-01-01

    We study the interaction between two magnetic adatom impurities in graphene using the Anderson model. The two-impurity Anderson Hamiltonian is solved numerically by using the quantum Monte Carlo technique. We find that the inter-impurity spin susceptibility is strongly enhanced at low temperatures, significantly diverging from the well-known Ruderman-Kittel-Kasuya-Yoshida (RKKY) result which decays as $R^{-3}$.

  10. Magnetotransport evidence for irreversible spin reorientation in the collinear antiferromagnetic state of underdoped Nd2 -xCexCuO4

    Science.gov (United States)

    Dorantes, A.; Alshemi, A.; Huang, Z.; Erb, A.; Helm, T.; Kartsovnik, M. V.

    2018-02-01

    We make use of the strong spin-charge coupling in the electron-doped cuprate Nd2 -xCexCuO4 to probe changes in its spin system via magnetotransport measurements. We present a detailed study of the out-of-plane magnetoresistance in underdoped single crystals of this compound, including the nonsuperconducting, 0.05 ≤x ≤0.115 , and superconducting, 0.12 ≤x ≤0.13 , compositions. Special focus is put on the dependence of the magnetoresistance on the field orientation in the plane of the CuO2 layers. In addition to the kink at the field-induced transition between the noncollinear and collinear antiferromagnetic configurations, a sharp irreversible feature is found in the angle-dependent magnetoresistance of all samples in the high-field regime, at field orientations around the Cu-O-Cu direction. The obtained behavior can be explained in terms of field-induced reorientation of Cu2 + spins within the collinear antiferromagnetic state. It is therefore considered an unambiguous indication of the long-range magnetic order.

  11. Universal scaling of Néel temperature, staggered magnetization density, and spin-wave velocity of three-dimensional disordered and clean quantum antiferromagnets

    Science.gov (United States)

    Tan, D.-R.; Jiang, F.-J.

    2017-02-01

    The Néel temperature, staggered magnetization density, as well as the spin-wave velocity of a three-dimensional (3D) quantum Heisenberg model with antiferromagnetic disorder (randomness) are calculated using first-principles nonperturbative quantum Monte Carlo simulations. In particular, we examine the validity of universal scaling relations that are related to these three studied physical quantities. These relations are relevant to experimental data and are firmly established for clean (regular) 3D dimerized spin-1/2 Heisenberg models. Remarkably, our numerical results show that the considered scaling relations remain true for the investigated model with the introduced disorder. In addition, while the presence of disorder may change the physical properties of regular dimerized models, hence leading to different critical theories, both the obtained data of Néel temperature and staggered magnetization density in our study are fully compatible with the expected critical behavior for clean dimerized systems. As a result, it is persuasive to conclude that the related quantum phase transitions of the considered disordered model and its clean analogues are governed by the same critical theory, which is not always the case in general. Finally, we also find smooth scaling curves even emerging when both the data of the investigated disordered model as well as its associated clean system are taken into account concurrently. This in turn implies that, while in a restricted sense, the considered scaling relations for 3D spin-1/2 antiferromagnets are indeed universal.

  12. Quantum spin correction scheme based on spin-correlation functional for Kohn-Sham spin density functional theory

    International Nuclear Information System (INIS)

    Yamanaka, Shusuke; Takeda, Ryo; Nakata, Kazuto; Takada, Toshikazu; Shoji, Mitsuo; Kitagawa, Yasutaka; Yamaguchi, Kizashi

    2007-01-01

    We present a simple quantum correction scheme for ab initio Kohn-Sham spin density functional theory (KS-SDFT). This scheme is based on a mapping from ab initio results to a Heisenberg model Hamiltonian. The effective exchange integral is estimated by using energies and spin correlation functionals calculated by ab initio KS-SDFT. The quantum-corrected spin-correlation functional is open to be designed to cover specific quantum spin fluctuations. In this article, we present a simple correction for dinuclear compounds having multiple bonds. The computational results are discussed in relation to multireference (MR) DFT, by which we treat the quantum many-body effects explicitly

  13. Magnetic phase diagram and multiferroicity of Ba3MnNb2O9: A spin-5/2 triangular lattice antiferromagnet with weak easy-axis anisotropy

    Science.gov (United States)

    Lee, M.; Choi, E. S.; Huang, X.; Ma, J.; Dela Cruz, C. R.; Matsuda, M.; Tian, W.; Dun, Z. L.; Dong, S.; Zhou, H. D.

    2015-03-01

    We have performed magnetic, electric, thermal, and neutron powder diffraction (NPD) experiments as well as density functional theory (DFT) calculations on Ba3MnNb2O9. All results suggest that Ba3MnNb2O9 is a spin-5/2 triangular lattice antiferromagnet (TLAF) with weak easy-axis anisotropy. At zero field, we observed a narrow two-step transition at TN 1 = 3.4 K and TN 2 = 3.0 K. The neutron diffraction measurement and the DFT calculation indicate a 120° spin structure in the ab plane with out-of-plane canting at low temperatures. With increasing magnetic field, the 120° spin structure evolves into up-up-down (uud) and oblique phase showing successive magnetic phase transitions, which fits well to the theoretical prediction for the 2D Heisenberg TLAF with classical spins. Multiferroicity is observed when the spins are not collinear but suppressed in the uud and the oblique phase. We discuss the results in comparison with our previous works on its sister compounds with small spins, Ba3NiNb2O9 (S = 1) (J. Hwang et al ., Phys. Rev. Lett. 109, 257205 (2012) and Ba3CoNb2O9 (S = 1/2) (M. Lee et al ., Phys. Rev. B 89, 104420 (2014)). NHMFL is supported by NSF, the state of Florida and US DOE. ORNL HFIR was sponsored by U.S. DOE.

  14. Paramagnetic Spin Correlations in CaFe2As2 Single Crystals

    International Nuclear Information System (INIS)

    Omar Diallo, Souleymane; Pratt, Daniel; Fernandes, Rafael; Tian, Wei; Zarestky, J.L.; Lumsden, Mark D.; Perring, T.G.; Broholm, C.; Ni, Ni; Budko, S.L.; Canfield, Paul; Li, Haifeng; Vaknin, D.; Kreyssig, A.; Goldman, A.I.; Mcqueeney, R.J.

    2010-01-01

    Magnetic correlations in the paramagnetic phase of CaFe2As2(TN=172 K) have been examined by means of inelastic neutron scattering from 180 K ( 1.05TN) up to 300 K (1.8TN). Despite the first-order nature of the magnetic ordering, strong but short-ranged antiferromagnetic (AFM) correlations are clearly observed. These correlations, which consist of quasielastic scattering centered at the wave vector QAFM of the low-temperature AFM structure, are observed up to the highest measured temperature of 300 K and at high energy transfer ( >60 meV). The L dependence of the scattering implies rather weak interlayer coupling in the tetragonal c direction corresponding to nearly two-dimensional fluctuations in the (ab) plane. The spin correlation lengths within the Fe layer are found to be anisotropic, consistent with underlying fluctuations of the AFM stripe structure. Similar to the cobalt-doped superconducting BaFe2As2 compounds, these experimental features can be adequately reproduced by a scattering model that describes short-ranged and anisotropic spin correlations with overdamped dynamics.

  15. Femtosecond switching of magnetism via strongly correlated spin-charge quantum excitations.

    Science.gov (United States)

    Li, Tianqi; Patz, Aaron; Mouchliadis, Leonidas; Yan, Jiaqiang; Lograsso, Thomas A; Perakis, Ilias E; Wang, Jigang

    2013-04-04

    The technological demand to push the gigahertz (10(9) hertz) switching speed limit of today's magnetic memory and logic devices into the terahertz (10(12) hertz) regime underlies the entire field of spin-electronics and integrated multi-functional devices. This challenge is met by all-optical magnetic switching based on coherent spin manipulation. By analogy to femtosecond chemistry and photosynthetic dynamics--in which photoproducts of chemical and biochemical reactions can be influenced by creating suitable superpositions of molecular states--femtosecond-laser-excited coherence between electronic states can switch magnetic order by 'suddenly' breaking the delicate balance between competing phases of correlated materials: for example, manganites exhibiting colossal magneto-resistance suitable for applications. Here we show femtosecond (10(-15) seconds) photo-induced switching from antiferromagnetic to ferromagnetic ordering in Pr0.7Ca0.3MnO3, by observing the establishment (within about 120 femtoseconds) of a huge temperature-dependent magnetization with photo-excitation threshold behaviour absent in the optical reflectivity. The development of ferromagnetic correlations during the femtosecond laser pulse reveals an initial quantum coherent regime of magnetism, distinguished from the picosecond (10(-12) seconds) lattice-heating regime characterized by phase separation without threshold behaviour. Our simulations reproduce the nonlinear femtosecond spin generation and underpin fast quantum spin-flip fluctuations correlated with coherent superpositions of electronic states to initiate local ferromagnetic correlations. These results merge two fields, femtosecond magnetism in metals and band insulators, and non-equilibrium phase transitions of strongly correlated electrons, in which local interactions exceeding the kinetic energy produce a complex balance of competing orders.

  16. Ferro- and antiferro-magnetism in (Np, Pu)BC

    Czech Academy of Sciences Publication Activity Database

    Klimczuk, T.; Shick, Alexander; Kozub, Agnieszka L.; Griveau, J.C.; Colineau, E.; Falmbigl, M.; Wastin, F.; Rogl, P.

    2015-01-01

    Roč. 3, č. 4 (2015), "041803-1"-"041803-9" ISSN 2166-532X R&D Projects: GA ČR GA15-07172S Institutional support: RVO:68378271 Keywords : ferromagetism * antiferromagnetism * magnetic anisotropy * strong electron correlations * spin-orbit coupling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.323, year: 2015

  17. Muon spin-relaxation measurements of spin-correlation decay in spin-glass AgMn

    International Nuclear Information System (INIS)

    Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Gupta, L.C.

    1983-01-01

    The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin-glass temperature in AgMn is found to obey an algebraic form given by (H)/sup nu-1/, with nu = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as t - /sup nu/, in agreement with mean field theories of spin-glass dynamics which yield nu less than or equal to 0.5. Near the glass temperature the agreement between the data and theory is not as good

  18. Classification for the universal scaling of Néel temperature and staggered magnetization density of three-dimensional dimerized spin-1/2 antiferromagnets

    Science.gov (United States)

    Tan, D.-R.; Li, C.-D.; Jiang, F.-J.

    2018-03-01

    Inspired by the recent theoretical development relevant to the experimental data of TlCuCl3, particularly those associated with the universal scaling between the Néel temperature TN and the staggered magnetization density Ms, we carry out a detailed investigation of three-dimensional (3D) dimerized quantum antiferromagnets using the first-principles quantum Monte Carlo calculations. Through this study we wish to better understand the microscopic effects on these scaling relations of TN and Ms, hence to shed light on some of the observed inconsistency between the theoretical and the experimental results. Remarkably, for the considered 3D dimerized models, we find that the established universal scaling relations are not only valid, but can each be categorized within its kind by the amount of stronger antiferromagnetic couplings connected to each spin. Convincing numerical evidence is provided to support the validity of this classification scheme. Based on all the related results known in the literature, we further argue that the proposed categorization for the universal scaling investigated in our paper should be applicable for 3D dimerized spin systems with (certain kinds of) quenched disorder and (or) on lattice geometries other than those considered here. The relevance of the outcomes presented in this investigation to the experiments of TlCuCl3 is briefly discussed as well.

  19. Quasistatic spin correlations in the frustrated spin-chain cuprate Li{sub 2}ZrCuO{sub 4} above T{sub N}

    Energy Technology Data Exchange (ETDEWEB)

    Arango, Yulieth; Buechner, Bernd [Institute for Solid State and Material Research, IFW Dresden (Germany); Vavilova, Evgeniya [Kazan Physical Technical Institute, Kazan (Russian Federation); Kataev, Vladik [Institute for Solid State and Material Research, IFW Dresden (Germany); Kazan Physical Technical Institute, Kazan (Russian Federation); Volkova, Olga; Vasilyev, Aleksander [Moscow State University (Russian Federation)

    2008-07-01

    Li{sub 2}ZrCuO{sub 4} is a new frustrated quasi-1D spin system with unusual thermodynamic properties due to its proximity to the ferromagnetic critical point. This material contains CuO{sub 2} chains along the crystallographic c-axis, with frustrated exchange interactions between the Cu spins S=1/2. We carried out high field Cu{sup 2+} ESR and {sup 7}Li-NMR measurements on an oriented powder, in a broad temperature range. The ESR data reveal temperature and orientation dependent anisotropy of the g-factor, as well as a progressive broadening of the linewidth below T{approx}80 K. Two antiferromagnetic resonance modes were observed below T{sub N}{approx} 8 K in long range magnetically ordered state. Surprisingly these modes can be seen also in an extended T-range above T{sub N}. This is in an agreement with the unusual {sup 7}Li-NMR linewidth and relaxation rates behaviour above T{sub N}. The data analysis suggests the occurrence of quasi-static spin correlations in the chain planes (bc-plane) and anisotropic T-dependent internal field below 80 K. The presence of these features far above T{sub N} indicates a substantial frustration of spin-spin interactions in Li{sub 2}ZrCuO{sub 4}.

  20. Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity.

    Science.gov (United States)

    Zaliznyak, Igor; Savici, Andrei T; Lumsden, Mark; Tsvelik, Alexei; Hu, Rongwei; Petrovic, Cedomir

    2015-08-18

    We report neutron scattering measurements which reveal spin-liquid polymorphism in an "11" iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is tuned toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the other is the antiferromagnetic plaquette phase with broken C4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid-liquid phase transformation between these states, in the electronic spin system of FeTe(1-x)(S,Se)(x). We have thus discovered the remarkable physics of competing spin-liquid polymorphs in a correlated electron system approaching superconductivity. Our results facilitate an understanding of large swaths of recent experimental data in unconventional superconductors. In particular, the phase with lower C2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity for forming electronic nematic states which have been observed experimentally, in cuprate and iron-based superconductors alike.

  1. Spin correlations and spin-wave excitations in Dirac-Weyl semimetals

    Science.gov (United States)

    Araki, Yasufumi; Nomura, Kentaro

    We study correlations among magnetic dopants in three-dimensional Dirac and Weyl semimetals. Effective field theory for localized magnetic moments is derived by integrating out the itinerant electron degrees of freedom. We find that spin correlation in the spatial direction parallel to local magnetization is more rigid than that in the perpendicular direction, reflecting spin-momentum locking nature of the Dirac Hamiltonian. Such an anisotropy becomes stronger for Fermi level close to the Dirac points, due to Van Vleck paramagnetism triggered by spin-orbit coupling. One can expect topologically nontrivial spin textures under this anisotropy, such as a hedgehog around a single point, or a radial vortex around an axis, as well as a uniform ferromagnetic order. We further investigate the characteristics of spin waves in the ferromagnetic state. Spin-wave dispersion also shows a spatial anisotropy, which is less dispersed in the direction transverse to the magnetization than that in the longitudinal direction. The spin-wave dispersion anisotropy can be traced back to the rigidity and flexibility of spin correlations discussed above. This work was supported by Grant-in-Aid for Scientific Research (Grants No.15H05854, No.26107505, and No.26400308) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

  2. Magnetic properties of the strongly correlated chain antiferromagnet KTb(WO4)2

    International Nuclear Information System (INIS)

    Khatsko, E.; Loginov, A.; Cherny, A.; Rykova, A.

    2006-01-01

    The susceptibility and magnetization of a single crystal of KTb(WO 4 ) 2 has been measured in the temperature range 0.5-80 K in magnetic fields up to 6 T. It is shown that KTb(WO 4 ) 2 is an Ising magnet with only one component of the magnetic moment. The three-dimensional phase transition to the antiferromagnetically ordered state has been found below 0.7 K. This transition can be described in the molecular field two-level approximation. The principal exchange constant has been estimated. By using experimental data the magnetic structure of KTb(WO 4 ) 2 is proposed

  3. Two spin-canting textures in the antiferromagnetic phase AF1 of MnWO4 based on the new polar atomistic model in P2

    Science.gov (United States)

    Park, S.-H.; Liu, B.-Q.; Behal, D.; Pedersen, B.; Schneidewind, A.

    2018-04-01

    The low temperature antiferromagnetic (AF) phase of MnWO4 (the so-called AF1 phase) exhibits different spin-canting configurations at two Mn2+ sublattices of the (3  +  1)-dimensional magnetic structure. The suggested superspace group {{\\boldsymbol P}}2.1^\\prime(α, 1/2, γ)0s is a significant consequence of the polar space group {{\\boldsymbol P}} 2 true for the nuclear structure of MnWO4. Density functional theory calculations showed that its ground state prefers this two spin-canting system. The structural difference between two independent atomic sites for Mn (Mn a , Mn b ) is too small to allow microscopically detectable electric polarisation. However, this hidden intrinsic polar character allows AF1 two commensurately modulated spin-canting textures. This is considered as the prerequisite onset of the improper ferroelectricity enhanced by the helical spin order in the multiferroic phase AF2 of MnWO4.

  4. Focused issue on antiferromagnetic spintronics: An overview (Part of a collection of reviews on antiferromagnetic spintronics)

    KAUST Repository

    Jungwirth, T.

    2017-05-30

    This focused issue attempts to provide a comprehensive introduction into the field of antiferromagnetic spintronics. Apart from the brief overview below, it features five review articles. The intention is to cover in a coherent and complementary way key physical aspects of the antiferromagnetic spintronics research. These range from microelectronic memory devices and optical manipulation and detection of antiferromagnetic spins, to the fundamentals of antiferromagnetic dynamics in uniform or spin-textured systems, and to the interplay of antiferromagnetic spintronics with topological phenomena. The antiferromagnetic ordering can take a number of forms including fully compensated collinear, non-collinear, and non-coplanar magnetic lattices, compensated and uncompensated ferrimagnets, or metamagnetic materials hosting an antiferromagnetic to ferromagnetic phase transition. Apart from the variety of distinct magnetic crystal structures, the focused issue also encompasses spintronic phenomena and devices studied in antiferromagnet/ferromagnet heterostructures and in synthetic antiferromagnets.

  5. Electrical manipulation of a ferromagnet by an antiferromagnet

    Science.gov (United States)

    Tshitoyan, V.; Ciccarelli, C.; Mihai, A. P.; Ali, M.; Irvine, A. C.; Moore, T. A.; Jungwirth, T.; Ferguson, A. J.

    Several recent studies of antiferromagnetic (AFM) spintronics have focused on transmission and detection of spin-currents in AFMs. Efficient spin transmission through AFMs was inferred from experiments in FM/AFM/NM (normal metal) structures. Measurements in FM/AFM bilayers have demonstrated that a metallic AFM can also act as an efficient ISHE detector of the spin-current, with spin-Hall angles comparable to heavy NMs. Here we demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. We use an all-electrical excitation and detection technique of ferromagnetic resonance in a NiFe/IrMn bilayer. We observe antidamping-like spin torque acting on the NiFe generated by the in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to strong spin-orbit coupling, the AFM order in IrMn governs the observed phenomenon.

  6. Stable magnetic remanence in antiferromagnetic goethite.

    Science.gov (United States)

    Strangway, D W; McMahon, B E; Honea, R M

    1967-11-10

    Goethite, known to be antiferromagnetic, acquires thermoremanent magnetization at its Neel temperature of 120 degrees C. This remanence, extremely stable, is due to the presence of unbalanced spins in the antiferromagnetic structure; the spins may result from grain size, imperfections, or impurities.

  7. First example of a high-level correlated calculation of the indirect spin-spin coupling constants involving tellurium

    DEFF Research Database (Denmark)

    Rusakov, Yury Yu; Krivdin, Leonid B.; Østerstrøm, Freja From

    2013-01-01

    This paper documents a very first example of a high-level correlated calculation of spin-spin coupling constants involving tellurium taking into account relativistic effects, vibrational corrections and solvent effects for the medium sized organotellurium molecules. The 125Te-1H spin-spin coupling...

  8. Properties of spin-1/2 triangular-lattice antiferromagnets CuY2Ge2O8 and CuLa2Ge2O8

    Science.gov (United States)

    Cho, Hwanbeom; Kratochvílová, Marie; Sim, Hasung; Choi, Ki-Young; Kim, Choong Hyun; Paulsen, Carley; Avdeev, Maxim; Peets, Darren C.; Jo, Younghun; Lee, Sanghyun; Noda, Yukio; Lawler, Michael J.; Park, Je-Geun

    2017-04-01

    We found new two-dimensional (2D) quantum (S =1 /2 ) antiferromagnetic systems: Cu R E2G e2O8 (R E =Y and La). According to our analysis of high-resolution x-ray and neutron diffraction experiments, the Cu network of Cu R E2G e2O8 (R E =Y and La) exhibits a 2D triangular lattice linked via weak bonds along the perpendicular b axis. Our bulk characterizations from 0.08 to 400 K show that they undergo a long-range order at 0.51(1) and 1.09(4) K for the Y and La systems, respectively. Interestingly, they also exhibit field induced phase transitions. For theoretical understanding, we carried out the density functional theory (DFT) band calculations to find that they are typical charge-transfer-type insulators with a gap of Eg≅2 eV . Taken together, our observations make Cu R E2G e2O8 (R E =Y and La) additional examples of low-dimensional quantum spin triangular antiferromagnets with the low-temperature magnetic ordering.

  9. NMR on the antiferromagnetic S=1/2 Heisenberg spin chain Sr{sub 2}CuO{sub 3} under the impact of Ni impurities

    Energy Technology Data Exchange (ETDEWEB)

    Utz, Yannic; Hammerath, Franziska; Nishimoto, Satoshi; Drechsler, Stefan-Ludwig; Hess, Christian; Buechner, Bernd; Grafe, Hans-Joachim [IFW Dresden (Germany); Beesetty, Neela Sekhar; Saint-Martin, Romuald; Revcolevschi, Alexandre [SP2M-ICMMO UMR-CNRS, Universite Paris-Sud (France)

    2015-07-01

    We present {sup 63}Cu NMR measurements on single crystals of Sr{sub 2}CuO{sub 3} doped with different amounts of nickel and compare them to numerical DMRG results. The parent compound contains copper-oxygen chains with S=1/2 on the copper site coupled by a large antiferromagnetic exchange coupling J ∼ 2000 K and is known to be a good realization of the 1D Heisenberg model. The measurements show that replacing only a few of the S=1/2 Cu ions with S=1 Ni has a major impact on the magnetic properties of the spin chain system. An unusual line broadening in the low temperature NMR spectra reveals the existence of an impurity-induced local alternating magnetization (LAM), and exponentially decaying spin-lattice relaxation rates T{sup -1}{sub 1} towards low temperatures indicate the opening of a spin gap similar to Ca-doped Sr{sub 2}CuO{sub 3}. While the T{sup -1}{sub 1} measurements could be explained by pure chain segmentation, as expected for a S=0 impurity, the spectra can only be understood by taking the nickel.

  10. Measurements of $t\\overline{t}$ Spin Correlations in CMS

    CERN Document Server

    Beernaert, Kelly Simone

    2014-01-01

    We present an overview of the measurements of $t\\bar{t}$ spin correlations in the CMS Collaboration. We present two analyses both in the dilepton channel using proton-proton collisions at $\\sqrt{s}\\, =\\, 7$ TeV based on an integrated luminosity of 5.0 fb$^{-1}$. The spin correlations and polarization are measured using angular asymmetries. The results are consistent with unpolarized top quarks and Standard Model spin correlation. The second analysis sets a limit on the real part of the top-quark chromo-magnetic dipole moment of $-0.043\\, <\\, Re({\\hat{\\mu}}_{t})\\, <\\, 0.117$ at $95\\,%$ confidence level through the measured azimuthal angle difference between the two charged leptons from $t\\bar{t}$ production.

  11. 89Y NMR observation of ferromagnetic and antiferromagnetic spin fluctuations in the collapsed tetragonal phase of YFe2(Ge,Si)2

    Science.gov (United States)

    Srpčič, J.; Jeglič, P.; Felner, I.; Lv, Bing; Chu, C. W.; Arčon, D.

    2017-11-01

    The surprising discovery of tripling the superconducting critical temperature of KFe2As2 at high pressures has led to an intriguing question of how the superconductivity in the collapsed tetragonal phase differs from that in the noncollapsed phases of Fe-based superconductors. Here we report a 89Y nuclear magnetic resonance study of YFe2GexSi2 -x compounds whose electronic structure is similar to that of iron-pnictide collapsed tetragonal phases already at ambient pressure. We find that Fe(Ge,Si) layers show ferromagnetic spin fluctuations, whereas the layers are coupled antiferromagnetically. Furthermore, localized moments attributed either to Fe interstitial or antisite defects may account for magnetic impurity pair-breaking effects, thus explaining the substantial variation of superconductivity among different YFe2Ge2 samples.

  12. Transverse spin and momentum correlations in quantum ...

    Indian Academy of Sciences (India)

    Collaboration [2] describes correlations of the intrinsic quark transverse momen- tum and the transverse nucleon ..... These results are in agreement with the large Nc predictions [41], Bag. Model results reported in [42], ..... work is supported by a grant from the US Department of Energy under contract. DE-FG02-07ER41460.

  13. Coherent and correlated spin transport in nanoscale superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Morten, Jan Petter

    2008-03-15

    the system varies from e.g. ballistic conductors or tunnel barriers. In the tunneling case, we calculate the magnetization-dependent full counting statistics, which determines all noise properties including the cross-correlations that can resolve the contributions due to crossed Andreev reflection and direct electron transport. We evaluate the magnetization-dependent two-particle probability that the constituents of spin-entangled pairs from crossed Andreev reflection flow into different ferromagnetic contacts. This probability implies violation of a Bell inequality, and determines the performance of a superconductor-ferromagnet entangler. (author). 105 refs., 13 figs

  14. Spin disorder and order in quasi-2D triangular Heisenberg antiferromagnets: comparative study of FeGa2S4, Fe2Ga2S5, and NiGa2S4.

    Science.gov (United States)

    Nakatsuji, S; Tonomura, H; Onuma, K; Nambu, Y; Sakai, O; Maeno, Y; Macaluso, R T; Chan, Julia Y

    2007-10-12

    Our single crystal study reveals that the single-layer S=2 triangular Heisenberg antiferromagnet FeGa2S4 forms a frozen spin-disordered state, similar to the S=1 isostructural magnet NiGa2S4. In this state, the magnetic specific heat C{M} is not only insensitive to the field, but shows a T2 dependence that scales to C{M} of NiGa2S4, suggesting the same underlying mechanism of the 2D coherent behavior. In contrast, the bilayer system Fe2Ga2S5 exhibits a 3D antiferromagnetic order.

  15. Spin delocalization phase transition in a correlated electrons model

    International Nuclear Information System (INIS)

    Huerta, L.

    1990-11-01

    In a simplified one-site model for correlated electrons systems we show the existence of a phase transition corresponding to spin delocalization. The system becomes a solvable model and zero-dimensional functional techniques are used. (author). 7 refs, 3 figs

  16. Quantum spin correlations in relativistic Møller scattering

    Directory of Open Access Journals (Sweden)

    Caban Paweł

    2017-01-01

    Full Text Available We present the relativistic spin correlation function (and the corresponding probabilities for a pair of polarized electrons originating from the Moller scattering. This particular state is easy to prepare experimentally; therefore, the results are discussed in view of a possible measurement. We also discuss the state after the Moller scattering in terms of entanglement and polarization transfer.

  17. Spin gap and antiferromagnetic correlations in the kondo insulator CeNiSn

    DEFF Research Database (Denmark)

    Mason, T.E.; Aeppli, G.; Ramirez, A.P.

    1992-01-01

    Neutron scattering measurements show that the crossover (at T less than or similar to 10 K) from metallic heavy-fermion to semiconducting behavior coincides with the formation of a gap in the magnetic excitation spectrum of CeNiSn. In contrast to the simple band picture of an insulator, the gap...

  18. Numerical study of the enlarged O(5) symmetry of the 3D antiferromagnetic RP2 spin model

    International Nuclear Information System (INIS)

    Fernandez, L.A.; Martin-Mayor, V.; Sciretti, D.; Tarancon, A.; Velasco, J.L.

    2005-01-01

    We investigate by means of Monte Carlo simulation and finite-size scaling analysis the critical properties of the three-dimensional O(5) non-linear σ model and of the antiferromagnetic RP 2 model, both of them regularized on a lattice. High accuracy estimates are obtained for the critical exponents, universal dimensionless quantities and critical couplings. It is concluded that both models belong to the same universality class, provided that rather non-standard identifications are made for the momentum-space propagator of the RP 2 model. We have also investigated the phase diagram of the RP 2 model extended by a second-neighbor interaction. A rich phase diagram is found, where most of the phase transitions are of the first order

  19. Muon spin relaxation studies in strongly correlated electron systems

    Science.gov (United States)

    Uemura, Y. J.; Luke, G. M.

    1993-05-01

    We describe recent progress of muon spin relaxation (μSR) studies in heavy-fermion (HF) and other strongly correlated electron systems. Measurements of the magnetic field penetration depth λ in HF superconductors UPt 3, URu 2Si 2, UPd 2Al 3 and U 2PtC 2 have revealed that these systems are characterized by large ratios Tc/ TF = 0.1-0.01 of Tc vs Fermi temperature TF derived from λ. This feature is common to high- Tc cuprate and other exotic superconductors. Zero-field μSR studies of magnetic order have elucidated a cross-over from spin glass ordering to nonmagnetic ground states in the ‘quadrupolar Kondo regime’ of (Y 1- xU x)Pd 3, and also suggested a possibility of incommensurate spin-density-wave (SDW) ordering in UNi 2Al 3.

  20. Antiferromagnetic spin fluctuations and unconventional nodeless superconductivity in an iron-based new superconductor (Ca4Al2O(6-y))(Fe2As2): 75As nuclear quadrupole resonance study.

    Science.gov (United States)

    Kinouchi, H; Mukuda, H; Yashima, M; Kitaoka, Y; Shirage, P M; Eisaki, H; Iyo, A

    2011-07-22

    We report 75As nuclear quadrupole resonance studies on (Ca4Al2O(6-y))(Fe2As2) with T(c) = 27  K. Measurement of nuclear-spin-relaxation rate 1/T1 has revealed a significant development of two-dimensional antiferromagnetic spin fluctuations down to T(c) in association with the smallest As-Fe-As bond angle. Below T(c), the temperature dependence of 1/T1 without any trace of the coherence peak is well accounted for by a nodeless s(±)-wave multiple-gaps model. From the fact that its T(c) is comparable to T(c) = 28  K in the optimally doped LaFeAsO(1-y) in which antiferromagnetic spin fluctuations are not dominant, we remark that antiferromagnetic spin fluctuations are not a unique factor for enhancing T(c) among Fe-based superconductors, but a condition for optimizing superconductivity should be addressed from the lattice structure point of view.

  1. Correlation functions of the spin chains. Algebraic Bethe Ansatz approach

    International Nuclear Information System (INIS)

    Kitanine, N.

    2007-09-01

    Spin chains are the basic elements of integrable quantum models. These models have direct applications in condense matter theory, in statistical physics, in quantum optics, in field theory and even in string theory but they are also important because they enable us to solve, in an exact manner, non-perturbative phenomena that otherwise would stay unresolved. The method described in this work is based on the algebraic Bethe Ansatz. It is shown how this method can be used for the computation of null temperature correlation functions of the Heisenberg 1/2 spin chain. The important point of this approach is the solution of the inverse quantum problem given by the XXZ spin chain. This solution as well as a simple formulae for the scalar product of the Bethe states, have enabled us to get the most basic correlation functions under the form of multiple integrals. The formalism of multiple integrals open the way for asymptotic analysis for a few physical quantities like the probability of vacuum formation. It is worth noticing that this formalism can give exact results for two-point functions that are the most important correlation functions for applications. A relationship has been discovered between these multiple integrals and the sum of the form factors. The results have been extended to dynamical correlation functions. (A.C.)

  2. High-order study of the quantum critical behavior of a frustrated spin-1/2 antiferromagnet on a stacked honeycomb bilayer

    Science.gov (United States)

    Bishop, R. F.; Li, P. H. Y.

    2017-12-01

    We study a frustrated spin-1/2 J1-J2-J3-J1⊥ Heisenberg antiferromagnet on an A A -stacked bilayer honeycomb lattice. In each layer we consider nearest-neighbor (NN), next-nearest-neighbor, and next-next-nearest-neighbor antiferromagnetic (AFM) exchange couplings J1,J2 , and J3, respectively. The two layers are coupled with an AFM NN exchange coupling J1⊥≡δ J1 . The model is studied for arbitrary values of δ along the line J3=J2≡α J1 that includes the most highly frustrated point at α =1/2 , where the classical ground state is macroscopically degenerate. The coupled cluster method is used at high orders of approximation to calculate the magnetic order parameter and the triplet spin gap. We are thereby able to give an accurate description of the quantum phase diagram of the model in the α δ plane in the window 0 ≤α ≤1 ,0 ≤δ ≤1 . This includes two AFM phases with Néel and striped order, and an intermediate gapped paramagnetic phase that exhibits various forms of valence-bond crystalline order. We obtain accurate estimations of the two phase boundaries, δ =δci(α) , or equivalently, α =αc i(δ ) , with i =1 (Néel) and 2 (striped). The two boundaries exhibit an "avoided crossing" behavior with both curves being re-entrant. Thus, in this α δ window, Néel order exists only for values of δ in the range δc1 (α ) , with δc1 0 for αc 1(0 ) ≈0.49 (1 ) , and striped order similarly exists only for values of δ in the range δc2 (α ) , with δc2 αc2(0) ≈0.600 (5 ) and δc2 0 for αc 2(0 ) >α >α2<≈0.56 (1 ) .

  3. Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

    Science.gov (United States)

    Tshitoyan, V.; Ciccarelli, C.; Mihai, A. P.; Ali, M.; Irvine, A. C.; Moore, T. A.; Jungwirth, T.; Ferguson, A. J.

    2015-12-01

    We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.

  4. Local Field Response Method Phenomenologically Introducing Spin Correlations

    Science.gov (United States)

    Tomaru, Tatsuya

    2018-03-01

    The local field response (LFR) method is a way of searching for the ground state in a similar manner to quantum annealing. However, the LFR method operates on a classical machine, and quantum effects are introduced through a priori information and through phenomenological means reflecting the states during the computations. The LFR method has been treated with a one-body approximation, and therefore, the effect of entanglement has not been sufficiently taken into account. In this report, spin correlations are phenomenologically introduced as one of the effects of entanglement, by which multiple tunneling at anticrossing points is taken into account. As a result, the accuracy of solutions for a 128-bit system increases by 31% compared with that without spin correlations.

  5. pp spin correlations at high p/sub T/

    International Nuclear Information System (INIS)

    Auer, I.P.; Colton, E.; Ditzler, W.R.

    1980-01-01

    New data are presented for measurements of the spin correlation in pp reactions with longitudinally polarized beam and target. Data were obtained at 11.75 GeV/c for both elastic scattering and for π + - and π - -production at high p/sub T/ in pp reactions at 11.75 GeV/c. A comparison is made with recent predictions of quark-parton models

  6. Does long-range antiferromagnetism help or inhibit superconductivity?

    Science.gov (United States)

    Arrachea, Liliana; Aligia, A. A.

    1998-07-01

    We analyze the possible existence of a superconducting state in a background with long-range antiferromagnetism. We consider a generalized Hubbard model with nearest-neighbor correlated hopping in a square lattice. Near half filling, the model exhibits a d-wave-Bardeen-Cooper-Schrieffer (BCS) solution in the paramagnetic state. The superconducting solution would be enhanced by the antiferromagnetic background if the contribution of triplet pairs with d-wave symmetry and total momentum ( π, π) could be neglected. However, we find that due to their contribution, the coexistence of superconductivity and long-range antiferromagnetism is ruled out for large values of the Coulomb repulsion U. Spin-density wave fluctuations (SDWF) do not change this result.

  7. Incommensurate antiferromagnetism and magnetic correlations in CeCu6-xAux

    DEFF Research Database (Denmark)

    Stockert, O.; Lohneysen, H. von; Schröder, A.

    1997-01-01

    Magnetic ordering and correlations in single crystals of the heavy-fermion alloys CeCu5.8Au0.2 and CeCu5.9Au0.1 were investigated by elastic and inelastic neutron scattering. CeCu5.8Au0.2 orders with an incommensurate magnetic structure and a wave vector q = (+/- 0.79 0 0). Only dynamic...

  8. Antiferromagnetic correlations in icosahedral R-Mg-Zn quasicrystals (R rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, B.; Schmitt, D. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Powder neutron-diffraction experiments performed on R-Mg-Zn quasicrystals have shown for the first time the existence of magnetic ordering of the rare earth in these systems at low temperature (T{sub c} {<=} 6.5 K depending on the rare earth). Both narrow and broad magnetic diffraction peaks have been observed showing the presence of two different scales of magnetic correlations. (author). 3 refs.

  9. Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn2 + spins in (Ba1 -xKx) (Zn1-yMny) 2As2

    Science.gov (United States)

    Surmach, M. A.; Chen, B. J.; Deng, Z.; Jin, C. Q.; Glasbrenner, J. K.; Mazin, I. I.; Ivanov, A.; Inosov, D. S.

    2018-03-01

    Dilute magnetic semiconductors (DMS) are nonmagnetic semiconductors doped with magnetic transition metals. The recently discovered DMS material (Ba1 -xKx) (Zn1-yMny) 2As2 offers a unique and versatile control of the Curie temperature TC by decoupling the spin (Mn2 +, S =5 /2 ) and charge (K+) doping in different crystallographic layers. In an attempt to describe from first-principles calculations the role of hole doping in stabilizing ferromagnetic order, it was recently suggested that the antiferromagnetic exchange coupling J between the nearest-neighbor Mn ions would experience a nearly twofold suppression upon doping 20% of holes by potassium substitution. At the same time, further-neighbor interactions become increasingly ferromagnetic upon doping, leading to a rapid increase of TC. Using inelastic neutron scattering, we have observed a localized magnetic excitation at about 13 meV associated with the destruction of the nearest-neighbor Mn-Mn singlet ground state. Hole doping results in a notable broadening of this peak, evidencing significant particle-hole damping, but with only a minor change in the peak position. We argue that this unexpected result can be explained by a combined effect of superexchange and double-exchange interactions.

  10. Magnetotransport property of the hole-doped delafossite CuCr0.97Mg0.03O2 with a Spin-3/2 antiferromagnetic triangular sublattice

    Science.gov (United States)

    Okuda, Tetsuji; Oozono, Satoshi; Kihara, Takumi; Tokunaga, Masashi

    2013-06-01

    The magnetotransport property of a hole-doped delafossite CuCr0.97Mg0.03O2 with a spin-3/2 antiferromagnetic (AF) triangular sublattice was investigated by using a pulsed high magnetic field. A dramatic change of magnetoresistance was observed with a variation of temperature, which indicates that a spin fluctuation due to a competition between the AF and the ferromagnetic Hund's interactions is enhanced at temperatures around the Néel temperatures ( T N). The competition may lead to a partially-disordered state at temperatures below T N which may cause a nontrivial promotion of a 120° Néel state.

  11. Spin-flip configuration interaction singles with exact spin-projection: Theory and applications to strongly correlated systems.

    Science.gov (United States)

    Tsuchimochi, Takashi

    2015-10-14

    Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.

  12. Antiferromagnetic spintronics

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Martí, Xavier; Wadley, P.; Wunderlich, Joerg

    2016-01-01

    Roč. 11, č. 3 (2016), 231-241 ISSN 1748-3387 R&D Projects: GA MŠk(CZ) LM2011026; GA ČR GB14-37427G EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : antiferromagnets * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 38.986, year: 2016

  13. The Bell inequality and correlation of spin projection functions

    International Nuclear Information System (INIS)

    Andreev, V A

    2009-01-01

    The Bell inequality two-particle spin states are considered. It is shown that violation of this inequality at experimental verifications is connected with the fact that it is proved for some arbitrary random variables, but in experimental verification random variables of special type are used. A new inequality is constructed. It contains a correlation coefficient of random variables, measured at the experiment, and does not have to be violated at experimental verification. For factorizable and separable states it coincides with the usual Bell inequality.

  14. Quantum Correlation in Matrix Product States of One-Dimensional Spin Chains

    International Nuclear Information System (INIS)

    Zhu Jing-Min

    2015-01-01

    For our proposed composite parity-conserved matrix product state (MPS), if only a spin block length is larger than 1, any two such spin blocks have correlation including classical correlation and quantum correlation. Both the total correlation and the classical correlation become larger than that in any subcomponent; while the quantum correlations of the two nearest-neighbor spin blocks and the two next-nearest-neighbor spin blocks become smaller and for other conditions the quantum correlation becomes larger, i.e., the increase or the production of the long-range quantum correlation is at the cost of reducing the short-range quantum correlation, which deserves to be investigated in the future; and the ration of the quantum correlation to the total correlation monotonically decreases to a steady value as the spacing spin length increasing. (paper)

  15. Doping Dependence of Collective Spin and Orbital Excitations in the Spin-1 Quantum Antiferromagnet La2 -xSrxNiO4 Observed by X Rays

    Science.gov (United States)

    Fabbris, G.; Meyers, D.; Xu, L.; Katukuri, V. M.; Hozoi, L.; Liu, X.; Chen, Z.-Y.; Okamoto, J.; Schmitt, T.; Uldry, A.; Delley, B.; Gu, G. D.; Prabhakaran, D.; Boothroyd, A. T.; van den Brink, J.; Huang, D. J.; Dean, M. P. M.

    2017-04-01

    We report the first empirical demonstration that resonant inelastic x-ray scattering (RIXS) is sensitive to collective magnetic excitations in S =1 systems by probing the Ni L3 edge of La2 -xSrxNiO4 (x =0 , 0.33, 0.45). The magnetic excitation peak is asymmetric, indicating the presence of single and multi-spin-flip excitations. As the hole doping level is increased, the zone boundary magnon energy is suppressed at a much larger rate than that in hole doped cuprates. Based on the analysis of the orbital and charge excitations observed by RIXS, we argue that this difference is related to the orbital character of the doped holes in these two families. This work establishes RIXS as a probe of fundamental magnetic interactions in nickelates opening the way towards studies of heterostructures and ultrafast pump-probe experiments.

  16. Doping Dependence of Collective Spin and Orbital Excitations in the Spin-1 Quantum Antiferromagnet La_{2-x}Sr_{x}NiO_{4} Observed by X Rays.

    Science.gov (United States)

    Fabbris, G; Meyers, D; Xu, L; Katukuri, V M; Hozoi, L; Liu, X; Chen, Z-Y; Okamoto, J; Schmitt, T; Uldry, A; Delley, B; Gu, G D; Prabhakaran, D; Boothroyd, A T; van den Brink, J; Huang, D J; Dean, M P M

    2017-04-14

    We report the first empirical demonstration that resonant inelastic x-ray scattering (RIXS) is sensitive to collective magnetic excitations in S=1 systems by probing the Ni L_{3} edge of La_{2-x}Sr_{x}NiO_{4} (x=0, 0.33, 0.45). The magnetic excitation peak is asymmetric, indicating the presence of single and multi-spin-flip excitations. As the hole doping level is increased, the zone boundary magnon energy is suppressed at a much larger rate than that in hole doped cuprates. Based on the analysis of the orbital and charge excitations observed by RIXS, we argue that this difference is related to the orbital character of the doped holes in these two families. This work establishes RIXS as a probe of fundamental magnetic interactions in nickelates opening the way towards studies of heterostructures and ultrafast pump-probe experiments.

  17. Classical and quantum 'EPR'-spin correlations in the triplet state

    International Nuclear Information System (INIS)

    Barut, A.O.; Bozic, M.

    1987-01-01

    Quantum correlations and joint probabilities in the triplet state as well as the correlations of components of two correlated classical spin vectors, are evaluated. Correlations in the states with |S tot z |=1 are different from correlations in the state with S tot z =0 which may serve to distinguish different states of the triplet. As in the singlet case, we can reproduce quantum correlations by correlated classical spin vectors which also provide a precision of the notion of ''parallel spins''. Triplet state correlations could in principle be measured, for example, in the decay reaction J/ψ → e + e - for which there is a sufficiently large branching ratio. (author). 12 refs

  18. Constructing a magnetic handle for antiferromagnetic manganites

    Science.gov (United States)

    Glavic, Artur; Dixit, Hemant; Cooper, Valentino R.; Aczel, Adam A.

    2016-04-01

    An intrinsic property of antiferromagnetic materials is the compensation of the magnetic moments from the individual atoms that prohibits the direct interaction of the spin lattice with an external magnetic field. To overcome this limitation we have created artificial spin structures by heteroepitaxy between two bulk antiferromagnets SrMnO3 and NdMnO3. Here, we demonstrate that charge transfer at the interface results in the creation of thin ferromagnetic layers adjacent to A -type antiferromagnetism in thick NdMnO3 layers. A novel interference based neutron diffraction technique and polarized neutron reflectometry are used to confirm the presence of ferromagnetism in the SrMnO3 layers and to probe the relative alignment of antiferromagnetic spins induced by the coupling at the ferro- to antiferromagnet interface. A density functional theory analysis of the driving forces for the exchange reveals strong ferromagnetic interfacial coupling through quantifiable short range charge transfer. These results confirm a layer-by-layer control of magnetic arrangements that constitutes a promising step on a path towards isothermal magnetic control of antiferromagnetic arrangements as would be necessary in spin-based heterostructures like multiferroic devices.

  19. Stabilization of Long-Range Order by Additional Anisotropic Spins in Two-Dimensional Isotropic Heisenberg Antiferromagnets —A Possible Model of an Organic Compound with Magnetic Anions—

    Science.gov (United States)

    Shimahara, Hiroshi; Ito, Kazuhiro

    2014-11-01

    We examine a two-dimensional (2D) coupled antiferromagnetic (AF) Heisenberg model that consists of two subsystems: an isotropic S = 1/2 spin subsystem with strong AF exchange interactions (main system), and a uniaxial S = 5/2 spin subsystem with weak exchange interactions. This model is an example in which additional semiclassical degrees of freedom affect a quantum system; it also describes a possible stabilization mechanism of AF long-range order (LRO) in the 2D organic compound λ-(BETS)2FeCl4, where BETS stands for bis(ethylenedithio)tetraselenafulvalene. Previous experimental studies have revealed that 3d spins on FeCl4 anions passively follow the AF LRO of the π-electron system in the BETS layers, although the AF LRO is stabilized by the 3d spins themselves. To explain this paradoxical behavior, we examine a scenario in which the uniaxial anisotropy of the 3d spins stabilizes the AF LRO on an isotropic 2D π-spin system. We extend Green's function theory, called the Tyablikov approximation, to the present system, which describes spin-wave excitations and is consistent with the Mermin-Wagner theorem. It is shown that even extremely weak interactions with the uniaxial subsystem efficiently stabilize the AF LRO in the main system, even in the absence of AF exchange interactions in the uniaxial subsystem. The AF LRO is triggered by the uniaxial subsystem, but the sublattice magnetization remains smaller than that of the main system in the high-temperature region. These results are consistent with experimental data for λ-(BETS)2FeCl4 and λ-(BETS)2GaCl4; the latter does not have the 3d spins and does not exhibit the AF LRO.

  20. Shot noise as a probe of spin-correlated transport through single atoms

    Science.gov (United States)

    Pradhan, S.; Fransson, J.

    2018-03-01

    We address the shot noise in the tunneling current through a local spin, pertaining to recent experiments on magnetic adatoms and single molecular magnets. We show that both uncorrelated and spin-correlated scattering processes contribute vitally to the noise spectrum. The spin-correlated scattering processes provide an additional contribution to the Landauer-Büttiker shot noise expression, accounting for correlations between the tunneling electrons and the localized spin moment. By calculating the Fano factor, we show that both super- and sub-Poissonian shot noise can be described within our approach. Our theory provides transparent insights into noise spectroscopy, consistent with recent experiments using local probing techniques on magnetic atoms.

  1. Measurement of the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering

    International Nuclear Information System (INIS)

    Stuart, S.J.

    1982-08-01

    The experimental procedures and methods of data analysis used to measure the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering at thirteen different energies in the range 300 to 800 MeV are presented. The results compare favorably with previous data. Good agreement is found with phase shift predictions at energies below 500 MeV

  2. Strong electron correlation in photoionization of spin-orbit doublets

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Chernysheva, L.V.; Manson, S.T.; Msezane, A.M.; Radojevic, V.

    2002-01-01

    A new and explicitly many-body aspect of the 'leveraging' of the spin-orbit interaction is demonstrated, spin-orbit activated interchannel coupling, which can significantly alter the photoionization cross section of a spin-orbit doublet. As an example, it is demonstrated via a modified version of the spin-polarized random phase approximation with exchange, that a recently observed unexplained structure in the Xe 3d 5/2 photoionization cross section [A. Kivimaeki et al., Phys. Rev. A 63, 012716 (2000)] is entirely due to this effect. Similar features are predicted for Cs 3d 5/2 and Ba 3d 5/2

  3. Classical Antiferromagnetism in Kinetically Frustrated Electronic Models

    Science.gov (United States)

    Sposetti, C. N.; Bravo, B.; Trumper, A. E.; Gazza, C. J.; Manuel, L. O.

    2014-05-01

    We study, by means of the density matrix renormalization group, the infinite U Hubbard model—with one hole doped away from half filling—in triangular and square lattices with frustrated hoppings, which invalidate Nagaoka's theorem. We find that these kinetically frustrated models have antiferromagnetic ground states with classical local magnetization in the thermodynamic limit. We identify the mechanism of this kinetic antiferromagnetism with the release of the kinetic energy frustration, as the hole moves in the established antiferromagnetic background. This release can occur in two different ways: by a nontrivial spin Berry phase acquired by the hole, or by the effective vanishing of the hopping amplitude along the frustrating loops.

  4. Exchange and spin-fluctuation superconducting pairing in the strong correlation limit of the Hubbard model

    International Nuclear Information System (INIS)

    Plakida, N. M.; Anton, L.; Adam, S. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO); Adam, Gh. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO)

    2001-01-01

    A microscopical theory of superconductivity in the two-band singlet-hole Hubbard model, in the strong coupling limit in a paramagnetic state, is developed. The model Hamiltonian is obtained by projecting the p-d model to an asymmetric Hubbard model with the lower Hubbard subband occupied by one-hole Cu d-like states and the upper Hubbard subband occupied by two-hole p-d singlet states. The model requires two microscopical parameters only, the p-d hybridization parameter t and the charge-transfer gap Δ. It was previously shown to secure an appropriate description of the normal state properties of the high -T c cuprates. To treat rigorously the strong correlations, the Hubbard operator technique within the projection method for the Green function is used. The Dyson equation is derived. In the molecular field approximation, d-wave superconducting pairing of conventional hole (electron) pairs in one Hubbard subband is found, which is mediated by the exchange interaction given by the interband hopping, J ij = 4 (t ij ) 2 / Δ. The normal and anomalous components of the self-energy matrix are calculated in the self-consistent Born approximation for the electron-spin-fluctuation scattering mediated by kinematic interaction of the second order of the intraband hopping. The derived numerical and analytical solutions predict the occurrence of singlet d x 2 -y 2 -wave pairing both in the d-hole and singlet Hubbard subbands. The gap functions and T c are calculated for different hole concentrations. The exchange interaction is shown to be the most important pairing interaction in the Hubbard model in the strong correlation limit, while the spin-fluctuation coupling results only in a moderate enhancement of T c . The smaller weight of the latter comes from two specific features: its vanishing inside the Brillouin zone (BZ) along the lines, |k x | + |k y |=π pointing towards the hot spots and the existence of a small energy shell within which the pairing is effective. By

  5. Spin correlation and entanglement detection in Cooper pair splitters by current measurements using magnetic detectors

    Science.gov (United States)

    Busz, Piotr; Tomaszewski, Damian; Martinek, Jan

    2017-08-01

    We analyze a model of a double quantum dot Cooper pair splitter coupled to two ferromagnetic detectors and demonstrate the possibility of determination of spin correlation by current measurements. We use perturbation theory, taking account of the exchange interaction with the detectors, which leads to complex spin dynamics in the dots. This affects the measured spin and restricts the use of ferromagnetic detectors to the nonlinear current-voltage characteristic regime at the current plateau, where the relevant spin projection is conserved, in contrast to the linear current-voltage characteristic regime, in which the spin information is distorted. Moreover, we show that for separable states the spin correlation can only be determined in a limited parameter regime, much more restricted than in the case of entangled states. We propose an entanglement test based on the Bell inequality.

  6. Superconductivity by charge and spin fluctuations in strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Quintana, J. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Gonzalez-Leon, E. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Lopez Aguilar, F. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Puig-Puig, L. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Sanchez-Lopez, M.M. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme

    1995-02-01

    We obtain the effective potential from a screened coulombian interaction considering separately the interaction between fermions with parallel and antiparallel spins. In both cases we analyze the possibility of obtaining superconductivity. ((orig.)).

  7. Spin correlations in decay chains involving W bosons TH1"-->

    Science.gov (United States)

    Smillie, J. M.

    2007-08-01

    We study the extent to which spin assignments of new particles produced at the LHC can be deduced in the decay of a scalar or fermion C into a new stable (or quasi-stable) particle A through the chain C→B±q, B±→AW±, W±→ℓ±νℓ where ℓ=e,μ. All possible spin assignments of the particles A and B are considered. Explicit invariant mass distributions of the quark and lepton are given for each set of spins, valid for all masses. We also construct the asymmetry between the chains with a W- and those with a W+. The Kullback Leibler distance between the distributions is then calculated to give a quantitative measure of our ability to distinguish the different spin assignments.

  8. Quantum correlation properties in Matrix Product States of finite-number spin rings

    Science.gov (United States)

    Zhu, Jing-Min; He, Qi-Kai

    2018-02-01

    The organization and structure of quantum correlation (QC) of quantum spin-chains are very rich and complex. Hence the depiction and measures about the QC of finite-number spin rings deserved to be investigated intensively by using Matrix Product States(MPSs) in addition to the case with infinite-number. Here the dependencies of the geometric quantum discord(GQD) of two spin blocks on the total spin number, the spacing spin number and the environment parameter are presented in detail. We also compare the GQD with the total correlation(TC) and the classical correlation(CC) and illustrate its characteristics. Predictably, our findings may provide the potential of designing the optimal QC experimental detection proposals and pave the way for the designation of optimal quantum information processing schemes.

  9. The build up of the correlation between halo spin and the large-scale structure

    Science.gov (United States)

    Wang, Peng; Kang, Xi

    2018-01-01

    Both simulations and observations have confirmed that the spin of haloes/galaxies is correlated with the large-scale structure (LSS) with a mass dependence such that the spin of low-mass haloes/galaxies tend to be parallel with the LSS, while that of massive haloes/galaxies tend to be perpendicular with the LSS. It is still unclear how this mass dependence is built up over time. We use N-body simulations to trace the evolution of the halo spin-LSS correlation and find that at early times the spin of all halo progenitors is parallel with the LSS. As time goes on, mass collapsing around massive halo is more isotropic, especially the recent mass accretion along the slowest collapsing direction is significant and it brings the halo spin to be perpendicular with the LSS. Adopting the fractional anisotropy (FA) parameter to describe the degree of anisotropy of the large-scale environment, we find that the spin-LSS correlation is a strong function of the environment such that a higher FA (more anisotropic environment) leads to an aligned signal, and a lower anisotropy leads to a misaligned signal. In general, our results show that the spin-LSS correlation is a combined consequence of mass flow and halo growth within the cosmic web. Our predicted environmental dependence between spin and large-scale structure can be further tested using galaxy surveys.

  10. Microscopic origin of marginal Fermi-liquid in strongly correlated spin systems

    International Nuclear Information System (INIS)

    Protogenov, A.P.; Ryndyk, D.A.

    1992-08-01

    We consider the consequences of separation of spin and charge degrees of freedom in 2+1D strongly correlated spin systems. Self-consistent spin and charge motions induced by doping in sites of ground and dual lattices form such a spectrum of quasiparticles which together with the dispersionless character of the collective excitation spectrum and the chemical potential pinning in the band centre yield the necessary behavior of charge and spin polarizability to support the theory of marginal liquid formulated by C.M. Varma et al. (Phys. Rev. Lett. 63, 1996 (1989)). (author). 28 refs, 4 figs

  11. Theoretical investigations of quantum correlations in NMR multiple-pulse spin-locking experiments

    Science.gov (United States)

    Gerasev, S. A.; Fedorova, A. V.; Fel'dman, E. B.; Kuznetsova, E. I.

    2018-04-01

    Quantum correlations are investigated theoretically in a two-spin system with the dipole-dipole interactions in the NMR multiple-pulse spin-locking experiments. We consider two schemes of the multiple-pulse spin-locking. The first scheme consists of π /2-pulses only and the delays between the pulses can differ. The second scheme contains φ-pulses (0Quantum discord is obtained for the first scheme of the multiple-pulse spin-locking experiment at different temperatures.

  12. Exchange bias in diluted-antiferromagnet/antiferromagnet bilayers

    International Nuclear Information System (INIS)

    Mao, Zhongquan; Zhan, Xiaozhi; Chen, Xi

    2015-01-01

    The hysteresis-loop properties of a diluted-antiferromagnetic (DAF) layer exchange coupling to an antiferromagnetic (AF) layer are investigated by means of numerical simulations. Remarkable loop shift and coercivity enhancement are observed in such DAF/AF bilayers, while they are absent in the uncoupled DAF single layer. The influences of pinned domains, dilution, cooling field and DAF layer thickness on the loop shift are investigated systematically. The result unambiguously confirms an exchange bias (EB) effect in the DAF/AF bilayers. It also reveals that the EB effect originates from the pinned AF domains within the DAF layer. In contrast to conventional EB systems, frozen uncompensated spins are not found at the interface of the AF pinning layer. (paper)

  13. Anomalous spin disordered properties of strongly correlated honeycomb compound In3Cu2VO9

    Directory of Open Access Journals (Sweden)

    Shi-Qing Jia

    2017-05-01

    Full Text Available We study the ground-state and finite-temperature magnetic properties of an interlayer frustrated J1 − J2 − Jc Heisenberg model on three-dimensional honeycomb lattice by employing the Schwinger boson mean-field theory, focusing on the low-energy physics in In3Cu2VO9. We find that with the increase of interlayer coupling Jc from 0 to 3.6 meV, the interlayer frustrated system transits from an antiferromagnetic (AFM phase to a state with intralayer AFM order and interlayer disorder. This spin disordered phase explains not only the intralayer phase transition at TN = 38 K, but also the qualitative behaviors of the intermediate-temperature specific heat and magnetic susceptibility of In3Cu2VO9.

  14. Strong antiferromagnetic coupling of spins in the (MDABCO+)(C60·-) salt with 3D close packing of the C60·- radical anions (MDABCO+: N-methyldiazabicyclooctanium cation).

    Science.gov (United States)

    Konarev, Dmitri V; Khasanov, Salavat S; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N

    2014-06-01

    A new salt, (MDABCO(+))(C60(·-)) (1; MDABCO(+) = N-methyldiazabicyclooctanium cation), was obtained as single crystals. The crystal structure of 1 determined at 250 and 100 K showed 3D close packing of fullerenes with eight fullerene neighbors for each C60(·-). These neighbors are located at 10.01-10.11 Å center-to-center distances (250 K) and van der Waals interfullerene C⋅⋅⋅C contacts are formed with four fullerene neighbors arranged in the bc plane. Fullerene ordering observed below 160 K is accompanied by the appearance of one and a half independent C60(·-) and trebling of the unit cell along the b axis. Fullerenes are packed closer to each other at 100 K. As a result, fullerenes are located in the three-dimensional packing at 9.91-10.12 Å center-to-center distances and 18 short interfullerene C⋅⋅⋅C contacts are formed for each C60(·-). Although they are closed packed, fullerenes are not dimerized down to 1.9 K. Magnetic data indicate strong antiferromagnetic coupling of spins in the 70-300 K range with a Weiss temperature of Θ = -118 K. Magnetic susceptibility shows a round maximum at 46 K. Such behavior can be described well by the Heisenberg model for square two-dimensional antiferromagnetic coupling of spins with an exchange interaction of J/kB = -25.3 K. This magnetic coupling is one of the strongest observed for C60(·-) salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet with √{3} × √{3} -Type Distortion — Behavior around the Boundaries of the Intermediate Phase

    Science.gov (United States)

    Shimada, Alisa; Nakano, Hiroki; Sakai, Tôru; Yoshimura, Kazuyoshi

    2018-03-01

    The S = 1/2 triangular-lattice Heisenberg antiferromagnet with distortion is investigated by the numerical-diagonalization method. The examined distortion type is √{3} × √{3} . We study the case when the distortion connects the undistorted triangular lattice and the dice lattice. For the intermediate phase reported previously in this system, we obtain results of the boundaries of the intermediate phase for a larger system than those in the previous report and examine the system size dependence of the boundaries in detail. We also report the specific heat of this system, which shows a marked peak structure related to the appearance of the intermediate state.

  16. Femtosecond optomagnetism in dielectric antiferromagnets

    Science.gov (United States)

    Bossini, D.; Rasing, Th

    2017-02-01

    Optical femtosecond manipulation of magnetic order is attractive for the development of new concepts for ultrafast magnetic recording. Theoretical and experimental investigations in this research area aim at establishing a physical understanding of magnetic media in light-induced non-equilibrium states. Such a quest requires one to adjust the theory of magnetism, since the thermodynamical concepts of elementary excitations and spin alignment determined by the exchange interaction are not applicable on the femtosecond time-scale after the photo-excitation. Here we report some key milestones concerning the femtosecond optical control of spins in dielectric antiferromagnets, whose spin dynamics is by nature faster than that of ferromagnets and can be triggered even without any laser heating. The recent progress of the opto-magnetic effect in the sub-wavelength regime makes this exciting research area even more promising, in terms of both fundamental breakthroughs and technological perspectives.

  17. Spin correlations in (Mn,Fe2(P,Si magnetocaloric compounds above Curie temperature

    Directory of Open Access Journals (Sweden)

    X.F. Miao

    2016-06-01

    Full Text Available The longitudinal-field muon-spin relaxation (LF-μSR technique was employed to study the spin correlations in (Mn,Fe2(P,Si compounds above the ferromagnetic transition temperature (TC. The (Mn,Fe2(P,Si compound under study is found to show itinerant magnetism. The standard deviation of the magnetic field distribution of electronic origin increases with a decrease in temperature, which is attributed to the development of spin correlations. The anomalously low magnetic fluctuation rate is suggested to be another signature of the spin correlations. The development of pronounced magnetic fluctuations is in agreement with the observed deviation of the paramagnetic susceptibility from Curie–Weiss behavior. Our study sheds light on the magneto-elastic transition and the mixed magnetism in (Mn,Fe2(P,Si compounds.

  18. Study of quantum spin correlations of relativistic electron pairs - Testing nonlocality of relativistic quantum mechanics

    International Nuclear Information System (INIS)

    Bodek, K.; Rozpędzik, D.; Zejma, J.; Caban, P.; Rembieliński, J.; Włodarczyk, M.; Ciborowski, J.; Enders, J.; Köhler, A.; Kozela, A.

    2013-01-01

    The Polish-German project QUEST aims at studying relativistic quantum spin correlations of the Einstein-Rosen-Podolsky-Bohm type, through measurement of the correlation function and the corresponding probabilities for relativistic electron pairs. The results will be compared to theoretical predictions obtained by us within the framework of relativistic quantum mechanics, based on assumptions regarding the form of the relativistic spin operator. Agreement or divergence will be interpreted in the context of non-uniqueness of the relativistic spin operator in quantum mechanics as well as dependence of the correlation function on the choice of observables representing the spin. Pairs of correlated electrons will originate from the Mo/ller scattering of polarized 15 MeV electrons provided by the superconducting Darmstadt electron linear accelerator S-DALINAC, TU Darmstadt, incident on a Be target. Spin projections will be determined using the Mott polarimetry technique. Measurements (starting 2013) are planned for longitudinal and transverse beam polarizations and different orientations of the beam polarization vector w.r.t. the Mo/ller scattering plane. This is the first project to study relativistic spin correlations for particles with mass

  19. Spin-charge separation and anomalous correlation functions in the edge states of quantum hall liquids

    CERN Document Server

    Lee, H C

    1998-01-01

    First, we have investigated chiral edges of a quantum Hall liquids at filling factor nu=2. The separation of spin and charge degrees of freedom becomes manifest in the presence of long- range Coulomb interaction. Due to the spin-charge separation the tunneling density of states takes the form D(omega) approx ( -lnl omega l) sup 1 sup / sup 2. Experimentally, the spin-charge separation can be revealed in the temperature and voltage dependence of the tunneling current into Fermi liquid reservoir. Second, the charge and spin correlation functions of partially spin-polarized edge electrons of a quantum Hall bar are studied using effective Hamiltonian and bosonization techniques. In the presence of the Coulomb interaction between the edges with opposite chirality we find a different crossover behavior in spin and charge correlation functions. The crossover of the spin correlation function in the Coulomb dominated regime is characterized by an anomalous exponent, which originates from the finite value of the effect...

  20. Measurement of np elastic scattering spin-spin correlation parameters at 484, 634, and 788 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Garnett, R.W.

    1989-03-01

    The spin-spin correlation parameters C/sub LL/ and C/sub SL/ were measured for np elastic scattering at the incident neutron kinetic energy of 634 MeV. Good agreement was obtained with previously measured data. Additionally, the first measurement of the correlation parameter C/sub SS/ was made at the three energies, 484, 634, and 788 MeV. It was found that the new values, in general, do not agree well with phase shift predictions. A study was carried out to determine which of the isospin-0 partial waves will be affected by this new data. It was found that the /sup 1/P/sub 1/ partial wave will be affected significantly at all three measurement energies. At 634 and 788 MeV, the /sup 3/S/sub 1/ phase shifts will also change. 29 refs., 21 figs., 16 tabs.

  1. Measurement of np elastic scattering spin-spin correlation parameters at 484, 634, and 788 MeV

    International Nuclear Information System (INIS)

    Garnett, R.W.

    1989-03-01

    The spin-spin correlation parameters C/sub LL/ and C/sub SL/ were measured for np elastic scattering at the incident neutron kinetic energy of 634 MeV. Good agreement was obtained with previously measured data. Additionally, the first measurement of the correlation parameter C/sub SS/ was made at the three energies, 484, 634, and 788 MeV. It was found that the new values, in general, do not agree well with phase shift predictions. A study was carried out to determine which of the isospin-0 partial waves will be affected by this new data. It was found that the 1 P 1 partial wave will be affected significantly at all three measurement energies. At 634 and 788 MeV, the 3 S 1 phase shifts will also change. 29 refs., 21 figs., 16 tabs

  2. Magnetic field dependence of static correlations and spin dynamics of reentrant spin glasses studied by neutron scattering

    International Nuclear Information System (INIS)

    Hennion, M.; Hennion, B.; Mirebeau, I.; Lequien, S.; Hippert, F.

    1988-01-01

    We report small angle (SANS) and inelastic neutron scattering in zero and applied field for a-FeMn, NiMn and AuFe at composition where both ferromagnetic and frustration characters occur. We discuss the field evolution of the transverse correlations which arise below T c . A study of the field sensitivity of the spin wave anomalies in a-FeMn is reported

  3. Thermoinduced magnetization in nanoparticles of antiferromagnetic materials

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine

    2004-01-01

    We show that there is a thermoinduced contribution to the magnetic moment of nanoparticles of antiferromagnetic materials. It arises from thermal excitations of the uniform spin-precession mode, and it has the unusual property that its magnitude increases with increasing temperature. This has...

  4. The electronic structure of antiferromagnetic chromium

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1981-01-01

    The author has used the local spin density formalism to perform self-consistent calculations of the electronic structure of chromium in the non-magnetic and commensurate antiferromagnetic phases, as a function of the lattice parameter. A change of a few per cent in the atomic radius brings...

  5. Evolution of topological features in finite antiferromagnetic Heisenberg chains

    International Nuclear Information System (INIS)

    Chen Changfeng

    2003-01-01

    We examine the behavior of nonlocal topological order in finite antiferromagnetic Heisenberg chains using the density matrix renormalization group techniques. We find that chains with even and odd site parity show very different behavior in the topological string order parameter, reflecting interesting interplay of the intrinsic magnetic correlation and the topological term in the chains. Analysis of the calculated string order parameter as a function of the chain length and the topological angle indicates that S=1/2 and S=1 chains show special behavior while all S>1 chains have similar topological structure. This result supports an earlier conjecture on the classification of quantum spin chains based on an analysis of their phase diagrams. Implications of the topological behavior in finite quantum spin chains are discussed

  6. Correlation Dimension in Two-Dimensional Disordered Systems with Rashba Spin-Orbit Coupling

    International Nuclear Information System (INIS)

    Hernández, E M; Otero, J A; Delgado, F

    2016-01-01

    The metal-insulator phase transition that arises in the Integer Quantum Hall Effect has been characterized through the multifractal nature of extended states near the center of the Lowest Landau Level. In this work, we obtain numerical solutions for the one-electron Hamiltonian with disorder, where the correlation dimension of extended states in the first two Landau Levels is obtained, by taking into account the Rashba spin-orbit coupling in the Hamiltonian. Although, spin-orbit coupling at moderate field intensities has been determined experimentally, there is no theoretical evidence for the nature of the transition in this case. The correlation dimension of extended states for the resolved spin levels is obtained, and within the statistical error, it is found that the Rashba Hamiltonian in presence of disorder, belongs to the same universality class of spin unresolved systems. (paper)

  7. Quasiparticle excitations in frustrated antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Trumper, Adolfo E. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina)]. E-mail: trumper@ifir.edu.ar; Gazza, Claudio J. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina); Manuel, Luis O. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina)]. E-mail: manuel@ifir.edu.ar

    2004-12-31

    We have computed the quasiparticle wave function corresponding to a hole injected in a triangular antiferromagnet. We have taken into account multi-magnon contributions within the self-consistent Born approximation. We have found qualitative differences, under sign reversal of the integral transfer t, regarding the multi-magnon components and the own existence of the quasiparticle excitations. Such differences are due to the subtle interplay between magnon-assisted and free hopping mechanisms. We conclude that the conventional quasiparticle picture can be broken by geometrical frustration without invoking spin liquid phases.

  8. Quasiparticle excitations in frustrated antiferromagnets

    Science.gov (United States)

    Trumper, Adolfo E.; Gazza, Claudio J.; Manuel, Luis O.

    2004-12-01

    We have computed the quasiparticle wave function corresponding to a hole injected in a triangular antiferromagnet. We have taken into account multi-magnon contributions within the self-consistent Born approximation. We have found qualitative differences, under sign reversal of the integral transfer t, regarding the multi-magnon components and the own existence of the quasiparticle excitations. Such differences are due to the subtle interplay between magnon-assisted and free hopping mechanisms. We conclude that the conventional quasiparticle picture can be broken by geometrical frustration without invoking spin liquid phases.

  9. Quasiparticle excitations in frustrated antiferromagnets

    International Nuclear Information System (INIS)

    Trumper, Adolfo E.; Gazza, Claudio J.; Manuel, Luis O.

    2004-01-01

    We have computed the quasiparticle wave function corresponding to a hole injected in a triangular antiferromagnet. We have taken into account multi-magnon contributions within the self-consistent Born approximation. We have found qualitative differences, under sign reversal of the integral transfer t, regarding the multi-magnon components and the own existence of the quasiparticle excitations. Such differences are due to the subtle interplay between magnon-assisted and free hopping mechanisms. We conclude that the conventional quasiparticle picture can be broken by geometrical frustration without invoking spin liquid phases

  10. X-ray magnetic circular dichroism discloses surface spins correlation in maghemite hollow nanoparticles

    Science.gov (United States)

    Bonanni, Valentina; Basini, Martina; Peddis, Davide; Lascialfari, Alessandro; Rossi, Giorgio; Torelli, Piero

    2018-01-01

    The spin-spin correlations in hollow (H) and full (F) maghemite nanoparticles (NPs) have been studied by X-ray magnetic circular dichroism (XMCD). An unexpected XMCD signal was detected and analyzed under the application of a small field (μ0H = 160 Oe) and at remanence for both F and H NPs. Clear differences in the magnitude and in the lineshape of the XMCD spectra between F and H NPs emerged. By comparing XMCD measurements performed with a variable degree of surface sensitivity, we were able to address the specific role played by the surface spins in the magnetism of the NPs.

  11. Dimensional evolution of spin correlations in the magnetic pyrochlore Yb2Ti2O7

    DEFF Research Database (Denmark)

    Ross, K.A.; Yaraskavitch, L.R.; Laver, Mark

    2011-01-01

    The pyrochlore material Yb2Ti2O7 displays unexpected quasi-two-dimensional (2D) magnetic correlations within a cubic lattice environment at low temperatures, before entering an exotic disordered ground state below T=265 mK. We report neutron scattering measurements of the thermal evolution of the 2......D spin correlations in space and time. Short-range three-dimensional (3D) spin correlations develop below 400 mK, accompanied by a suppression in the quasielastic (QE) scattering below ∼0.2 meV. These show a slowly fluctuating ground state with spins correlated over short distances within a kagome...... analysis. ©2011 American Physical Society...

  12. Effect of grain size on charge and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} manganite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ade, Ramesh; Singh, Rajender, E-mail: rssp@uohyd.ernet.in

    2016-11-15

    In this work we report the electron spin resonance (ESR) and magnetization (M) studies to understand the effect of grain size (GS) on the charge ordering and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} manganite synthesized by sol–gel method. The suppression of charge ordering (CO), long-range antiferromagnetic (AFM) state, shifting of ferromagnetic (FM)-cluster glass (CG) transition towards higher temperatures and evolution of different magnetic correlations with decrease in GS are discussed in view of the changes in surface to volume ratio of nano-grains. - Highlights: • Effect of grain size on charge and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} are studied. • The samples with GS 27, 450 and 1080 nm were synthesized by sol–gel method. • The temperature dependent electron spin resonance (ESR) and magnetization measurements were carried out. • The evolution of different magnetic correlations with decrease in GS are ascribed to increase in surface to volume ratio of grains.

  13. Correlation functions of the spin chains. Algebraic Bethe Ansatz approach; Fonctions de correlation des chaines de spin. Approche de l'ansatz de Bethe algebrique

    Energy Technology Data Exchange (ETDEWEB)

    Kitanine, N

    2007-09-15

    Spin chains are the basic elements of integrable quantum models. These models have direct applications in condense matter theory, in statistical physics, in quantum optics, in field theory and even in string theory but they are also important because they enable us to solve, in an exact manner, non-perturbative phenomena that otherwise would stay unresolved. The method described in this work is based on the algebraic Bethe Ansatz. It is shown how this method can be used for the computation of null temperature correlation functions of the Heisenberg 1/2 spin chain. The important point of this approach is the solution of the inverse quantum problem given by the XXZ spin chain. This solution as well as a simple formulae for the scalar product of the Bethe states, have enabled us to get the most basic correlation functions under the form of multiple integrals. The formalism of multiple integrals open the way for asymptotic analysis for a few physical quantities like the probability of vacuum formation. It is worth noticing that this formalism can give exact results for two-point functions that are the most important correlation functions for applications. A relationship has been discovered between these multiple integrals and the sum of the form factors. The results have been extended to dynamical correlation functions. (A.C.)

  14. First Measurements of Spin Correlation Using Semi-leptonic $t\\bar{t}$ Events at ATLAS

    CERN Document Server

    Lemmer, Boris; The ATLAS collaboration

    2014-01-01

    The top quark decays before it hadronizes. Before its spin state can be changed in a process of strong interaction, it is directly transferred to the top quark decay products. The top quark spin can be deduced by studying angular distributions of the decay products. The Standard Model predicts the top/anti-top quark ($t\\bar{t}$) pairs to have correlated spins. The degree is sensitive to the spin and the production mechanisms of the top quark. Measuring the spin correlation allows to test the predictions. New physics effects can be reflected in deviations from the prediction. The measurement of the spin correlation of $t\\bar{t}$ pairs, produced at the LHC with a center-of-mass energy of $\\sqrt{s} = 7$ TeV and reconstructed with the ATLAS detector, is presented. The dataset corresponds to an integrated luminosity of 4.6 $\\textrm{fb}^{-1}$. $t\\bar{t}$ pairs are reconstructed in the $\\ell$+jets channel using a kinematic likelihood fit offering the identification of light up- and down-type quarks from the $t \\righ...

  15. Spin dynamics and structural phase transitions in quasi-2D R sub 2 CuO sub 4 (R=Pr, Sm and Eu) antiferromagnetics

    CERN Document Server

    Golovenchits, E I

    2001-01-01

    One studied spin dynamics and dynamics of lattice in R sub 2 CuO sub 4 (R = Pr, Sm, and Eu) crystals within 20-250 GHz frequency range and within 50350 K temperature interval. One detected abrupt variation of absorption coefficient within wide range of frequencies above 120 GHz at 20, 80 and 150 K temperatures in R sub 2 CuO sub 4 (R = Pr, Sm, and Eu), respectively. Absorption jumpings result from structural phase transitions. Wide ranges of spin-wave excitations were observed in all examined crystals in high-temperature phase. Close to temperatures of phase transitions within wide range of frequencies including frequencies corresponding to ranges of spin-wave excitations one observed lines of a absorption caused by lattice dynamics

  16. Measurement of the transverse spin correlations in the decay $Z \\rightarrow \\tau^+\\tau^-$

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Miquel, R; Mir, L M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rizzo, G; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Stacey, A M; Williams, M D; Ghete, V M; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Simion, S; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G

    1997-01-01

    For tau leptons produced in e^+e^- -> tau^+ tau^- interactions there are, in addition to the longitudinal spin correlations, two independent transverse spin correlations associated with the transverse (within the production plane) and normal (to the production plane) polarization components. A measurement of the transverse-transverse and transverse-normal tau spin correlations in the decay Z -> tau^+ tau^-, C_{TT} and C_{TN}, is presented based on the aplanarity angle of the decay products of both tau leptons. Using 80 pb^{-1} of data collected by ALEPH on the peak of the Z resonance, the results are C_{TT} = 1.06 +- 0.13 (stat) +- 0.05 (syst), and C_{TN} = 0.08 +- 0.13 (stat) +- 0.04 (syst). These values are in agreement with the Standard Model predictions, C_{TT} = 0.99 and C_{TN} = -0.01.

  17. Measurement of the transverse spin correlations in the decay Z -> τ+τ-

    Science.gov (United States)

    Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Coy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Miquel, R.; Mir, Ll. M.; Orteu, S.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Becker, U.; Bazarko, A. O.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rizzo, G.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Schmidt, M.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Stacey, A. M.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W.; Sloan, T.; Williams, M. I.; Galla, A.; Giehl, I.; Greene, A. M.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Coyle, P.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Choi, Y.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Schune, M.-H.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A.; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-02-01

    For τ leptons produced in e+e- -> τ+τ- interactions there are, in addition to the longitudinal spin correlations, two independent transverse spin correlations associated with the transverse (within the production plane) and normal (to the production plane) polarization components. A measurement of the transverse-transverse and transverse-normal τ spin correlations in the decay Z -> τ+τ-, CTT and CTN, is presented based on the aplanarity angle of the decay products of both τ leptons. Using 80 pb-1 of data collected by ALEPH on the peak of the Z resonance, the results are CTT = 1.06 +/- 0.13 (stat) +/- 0.05 (syst), and CTN = 0.08 +/- 0.13 (stat) +/- 0.04 (syst). These values are in agreement with the Standard Model predictions, CTT = 0.99 and CTN = -0.01.

  18. Novel domain wall dynamics in synthetic antiferromagnets

    Science.gov (United States)

    Yang, See-Hun; Parkin, Stuart

    2017-08-01

    In this article, we review fascinating new mechanisms on recently observed remarkable current driven domain wall motion in nanowires formed from perpendicularly magnetized synthetic antiferromagnets interfaced with heavy metallic layers, sources of spin-orbit torques. All the associated torques such as volumetric adiabatic and non-adiabatic spin-transfer-torque, spin-orbit torques, shape anisotropy field torques, Dzyaloshinkii-Moriya interaction torques and most importantly a new powerful torque, exchange coupling torque, will be discussed based on an analytical model that provides an intuitive description of domain wall dynamics in synthetic ferromagnets as well as synthetic antiferromagnets. In addition, the current driven DW motion in the presence of in-plane fields will be investigated, thus deepening our knowledge about the role of the exchange coupling torque, which will be of potential use for application to various novel spintronic devices.

  19. Measurement of spin amplitudes of neutron scattering on 159Tb by neutron diffraction method in antiferromagnets at ultra-low temperature

    International Nuclear Information System (INIS)

    Akopyan, G.G.; Alfimenkov, V.P.; Lason', L.; Ovchinnikov, O.N.; Sharapov, Eh.I.

    1975-01-01

    The measurement results are presented of the spin-spin amplitude for 159 Tb performed by the method of neutron diffraction by the flight time in the IBR-30 pulse reactor with samples cooled down to ultralow temperatures in a cryostat with 3 He dissolved in 4 He. The scattering angle has been fixed, neutrons incident upon the sample had a continuous energy spectrum, and the wave length satisfying the Bragg-Wolf condition has been determined by the neutron flight time required for given distance. Small-sized helium counters served as detectors. Preliminary measurements have been done with terbium dioxide and cobalt oxide whose intraatomic field values are not high. For main measurements TbAg intermetal has been chosen in which the magnetic field on a terbium nuclei is much greater. The difference of spin amplitudes of the thermal neutron scattering by terbium nuclei appeared to be equal to αsub(+-)αsub(-)=(0.35+-0.14) fermi. The spin-noncoherent scattering cross section has been obtained to be sigmasub(inc)=5+-4 mbn. The experiments have shown that the method is highly sensitive to a temperature

  20. Comparison between muon spin rotation and neutron scattering studies on the 3-dimensional magnetic ordering of La2CuO(4-y)

    Science.gov (United States)

    Uemura, Y. J.; Kossler, W. J.; Kempton, J. R.; Yu, X. H.; Schone, H. E.; Opie, D.; Stronach, C. E.; Brewer, J. H.; Kiefl, R. F.; Kreitzman, S. R.

    1988-01-01

    Muon spin rotation and neutron scattering studies on powder and single-crystal specimens of La2CuO(4-y) are compared. The apparent difference between the muon and neutron results for the ordered moment in the antiferromagnetic state is interpreted as the signature of increasingly short-ranged spatial spin correlations with increasing oxygen content.

  1. Polarized neutron powder diffraction studies of antiferromagnetic order in bulk and nanoparticle NiO

    DEFF Research Database (Denmark)

    Brok, Erik; Lefmann, Kim; Deen, Pascale P.

    2015-01-01

    In many materials it remains a challenge to reveal the nature of magnetic correlations, including antiferromagnetism and spin disorder. Revealing the spin structure in magnetic nanoparticles is further complicated by the large incoherent neutron scattering cross section from water adsorbed...... surface contribution to the magnetic anisotropy. Here we explore the potential use of polarized neutron diffraction to reveal the magnetic structure in NiO bulk and nanoparticle powders by applying the XYZ-polarization analysis method. Our investigations address in particular the spin orientation in bulk...... at the particle surfaces and by the broadening of diffraction peaks due to the finite crystallite size. Moreover, the spin structure in magnetic nanoparticles may deviate significantly from that of the corresponding bulk material because of the low-symmetry surroundings of surface atoms and the large relative...

  2. The phase diagrams and the order parameters of the diluted superlattice with antiferromagnetic interface coupling

    International Nuclear Information System (INIS)

    Oubelkacem, A.; El Aouad, N.; Bentaleb, M.; Laaboudi, B.; Saber, M.

    2004-01-01

    Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions, the magnetic properties of the diluted Ising superlattice consisting of two ferromagnetic materials A and B, with L a layers of diluted spins S a =((1)/(2)) and L b layers of diluted spins S b =1 with antiferromagnetic interface coupling are examined. For fixed values of the reduced exchange interactions and the concentration c of magnetic atoms, the phase diagrams, the two sublattice magnetizations and the total magnetization for the superlattice with the same spin S a =S b =((1)/(2)) and for S a =((1)/(2)), S b =1 are studied as a function of the temperature. We find a number of characteristic phenomena. In particular, the effect of the concentration c of magnetic atoms, the interlayer coupling and the layer thickness on both the compensation temperature and the magnetization profiles are clarified

  3. Angles and Daemons: Spin Correlations at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Nhan V. [Johns Hopkins Univ., Baltimore, MD (United States)

    2011-09-01

    The Large Hadron Collider has recently started collecting data, opening a new energy regime. This will allow us to probe further than ever before many of the current mysteries of the field. New physics beyond the Standard Model, the field's current paradigm, could manifest itself via new particles. In addition, the Higgs boson, hypothesized as a consequence of electroweak symmetry breaking, remains undiscovered. At the time of discovery, the properties of such particles will be unknown. In order to understand the nature of any new physics, it will be important to understand the properties of that new particle. Methods are presented for measuring its spin, parity and coupling to the Standard Model particles. These methods are implemented at the Compact Muon Solenoid experiment and an analysis is presented with the data collected during 2010 and 2011 running at the Large Hadron Collider. An application of these techniques is used to make a measurement of the weak mixing angle. A current status of the search for the Higgs boson is also presented.

  4. Electrical control of antiferromagnetic metal up to 15 nm

    Science.gov (United States)

    Zhang, PengXiang; Yin, GuFan; Wang, YuYan; Cui, Bin; Pan, Feng; Song, Cheng

    2016-08-01

    Manipulation of antiferromagnetic (AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in [Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction, the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics.

  5. Anisotropic Magnetoresistance in Antiferromagnetic Sr_{2}IrO_{4}

    Directory of Open Access Journals (Sweden)

    C. Wang

    2014-11-01

    Full Text Available We report point-contact measurements of anisotropic magnetoresistance (AMR in a single crystal of antiferromagnetic Mott insulator Sr_{2}IrO_{4}. The point-contact technique is used here as a local probe of magnetotransport properties on the nanoscale. The measurements at liquid nitrogen temperature reveal negative magnetoresistances (up to 28% for modest magnetic fields (250 mT applied within the IrO_{2} a-b plane and electric currents flowing perpendicular to the plane. The angular dependence of magnetoresistance shows a crossover from fourfold to twofold symmetry in response to an increasing magnetic field with angular variations in resistance from 1% to 14%. We tentatively attribute the fourfold symmetry to the crystalline component of AMR and the field-induced transition to the effects of applied field on the canting of antiferromagnetic-coupled moments in Sr_{2}IrO_{4}. The observed AMR is very large compared to the crystalline AMRs in 3d transition metal alloys or oxides (0.1%–0.5% and can be associated with the large spin-orbit interactions in this 5d oxide while the transition provides evidence of correlations between electronic transport, magnetic order, and orbital states. The finding of this work opens an entirely new avenue to not only gain a new insight into physics associated with spin-orbit coupling but also to better harness the power of spintronics in a more technically favorable fashion.

  6. Correlation driven charge and spin fluctuations in LaCoO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Karolak, Michael [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Izquierdo, Manuel [European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Synchrotron Soleil, L' Orme des Merisiers St-Aubin, BP-48, 91192, Gif-sur-Yvette (France); Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, 20355 Hamburg (Germany); Molodtsov, Serguei L. [European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Institute of Experimental Physics, Technische Universitaet Bergakademie Freiberg, 09599 Freiberg (Germany); ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg (Russian Federation); Lichtenstein, Alexander I. [Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, 20355 Hamburg (Germany)

    2015-07-01

    The spin transition in LaCoO{sub 3} has been investigated within the DFT+DMFT formalism using continuous time quantum Monte Carlo. Calculations on the experimental rhombohedral atomic structure with two Co sites per unit cell show that an independent treatment of the Co atoms results in a ground state with charge imbalance induced by electronic correlations. Each atom shows a contribution from either a d{sup 5} or a d{sup 7} state in addition to the main d{sup 6} state. These charged states play a relevant role in the spin transition which can be understood as a low spin-high spin (LS-HS) transition with significant contributions (∝ 10%) to the LS and HS states of d{sup 5} and d{sup 7} states. A thermodynamic analysis reveals that the introduction of charge imbalance significantly lowers the total energy of the system.

  7. Correlated calculations of indirect nuclear spin-spin coupling constants using second-order polarization propagator approximations: SOPPA and SOPPA(CCSD)

    DEFF Research Database (Denmark)

    Enevoldsen, Thomas; Oddershede, Jens; Sauer, Stephan P. A.

    1998-01-01

    We present correlated calculations of the indirect nuclear spin-spin coupling constants of HD, HF, H2O, CH4, C2H2, BH, AlH, CO and N2 at the level of the second-order polarization propagator approximation (SOPPA) and the second-order polarization propagator approximation with coupled-cluster sing...

  8. Pairing versus phase coherence of doped holes in distinct quantum spin backgrounds

    Science.gov (United States)

    Zhu, Zheng; Sheng, D. N.; Weng, Zheng-Yu

    2018-03-01

    We examine the pairing structure of holes injected into two distinct spin backgrounds: a short-range antiferromagnetic phase versus a symmetry protected topological phase. Based on density matrix renormalization group (DMRG) simulation, we find that although there is a strong binding between two holes in both phases, phase fluctuations can significantly influence the pair-pair correlation depending on the spin-spin correlation in the background. Here the phase fluctuation is identified as an intrinsic string operator nonlocally controlled by the spins. We show that while the pairing amplitude is generally large, the coherent Cooper pairing can be substantially weakened by the phase fluctuation in the symmetry-protected topological phase, in contrast to the short-range antiferromagnetic phase. It provides an example of a non-BCS mechanism for pairing, in which the paring phase coherence is determined by the underlying spin state self-consistently, bearing an interesting resemblance to the pseudogap physics in the cuprate.

  9. Quantum memory assisted probing of dynamical spin correlations.

    Science.gov (United States)

    Romero-Isart, O; Rizzi, M; Muschik, C A; Polzik, E S; Lewenstein, M; Sanpera, A

    2012-02-10

    We propose a method to probe time-dependent correlations of nontrivial observables in many-body ultracold lattice gases. The scheme uses a quantum nondemolition matter-light interface, first to map the observable of interest on the many-body system into the light and then to store coherently such information into an external system acting as a quantum memory. Correlations of the observable at two (or more) instances of time are retrieved with a single final measurement that includes the readout of the quantum memory. Such a method brings to reach the study of dynamics of many-body systems in and out of equilibrium by means of quantum memories in the field of quantum simulators.

  10. Evidence for spin correlation in ttˉ production

    Czech Academy of Sciences Publication Activity Database

    Abazov, V. M.; Abbott, B.; Acharya, B.S.; Kupčo, Alexander; Lokajíček, Miloš

    2012-01-01

    Roč. 108, č. 3 (2012), "032004-1"-"032004-7" ISSN 0031-9007 R&D Projects: GA MŠk LA08047 Institutional research plan: CEZ:AV0Z10100502 Keywords : Batavia TEVATRON Coll * correlation dilepton * pair production * final state * D0 * anti-p p interaction Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 7.943, year: 2012 http://prl.aps.org/abstract/PRL/v108/i3/e032004

  11. Effects of impurities and vortices on the low-energy spin excitations in high-Tc materials

    DEFF Research Database (Denmark)

    Andersen, Brian Møller; Graser, S.; Schmid, M.

    2011-01-01

    We review a theoretical scenario for the origin of the spin-glass phase of underdoped cuprate materials. In particular it is shown how disorder in a correlated d-wave superconductor generates a magnetic phase by inducing local droplets of antiferromagnetic order which eventually merge and form a ...... disorder and/or applied magnetic fields lead to a slowing down of the dynamical spin fluctuations in agreement with neutron scattering and muon spin rotation (mSR) experiments....

  12. Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures

    Science.gov (United States)

    Cho, Soonha; Baek, Seung-heon Chris; Lee, Kyeong-Dong; Jo, Younghun; Park, Byong-Guk

    2015-01-01

    The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques. PMID:26423608

  13. Nuclear spin-echo detection by means of perturbed angular correlations

    International Nuclear Information System (INIS)

    Kopvillem, U.H.; Shakhmuratova, L.N.

    1973-01-01

    Recent progress in theory and experiment of NMR detection by means of registration of angular distribution of nuclear radiation (NMR/RD) has stimulated us to consider the problem of spin-echo detection by means of nuclear radiation (s-E/RD). We have considered the case when each decaying radioactive nucleus suffers two pulses of magnetic radiofrequency field in its oriented excited state. The time-differential function of radiation's angular distribution is important in the S-E/RD problem, as it displays the motion of nuclear spins in time. The obtained results show that after the first pulse the anisotropy of radiation's angular distribution strongly decreases because of the dephasing of nuclear spins. After the second pulse there exist certain moments of time, determined by the nuclear spin and geometry of experiment, when the anisotropy of radiation's angular distribution sharply increases, whereas before and after these moments the function is swept. It is possible to observe the spin-echo by means of γ-γ angular correlations and by means of registration of γ-radiation's angular distribution after the nuclear reaction, for example after the bombardment of nuclei by a pulsed particle beam. The spin-echo nuclear radiation detection gives the possibility to explore the relaxation processes by the use of a relatively small number nuclei, as it is a microscopic method. (author)

  14. Measurement of Spin Correlation in Top Quark Pair Production at ATLAS

    CERN Document Server

    McLaughlan, Thomas

    2014-01-01

    This thesis presents a study of spin correlation in tt ̄ production in the ATLAS detector, in proton-proton collisions, corresponding to an integrated luminosity of 4.7 fb$^{−1}$, with a centre of mass energy of $\\sqrt{s}$ = 7 TeV. Both the dilepton and single lepton channels are considered, the latter providing a greater challenge due to the neccessity to reconstruct the down-type quark resulting from the W boson decay. A simple technique is employed to reconstruct single lepton $t\\bar{t}$ events, with the transverse angle between the charged lepton and down-type quark used as a probe of the spin correlation. In the dilepton channel, the transverse angle between both charged leptons is used. The extracted value of spin correlation in each channel is consistent with Standard Model predictions, with the result in the eμ channel alone sufficient to exclude a model without spin correlation at 7.8$\\sigma$. Also described is the author’s contribution to the maintenance and development of the Atlantis Event D...

  15. Anti-ferromagnetic Heisenberg model on bilayer honeycomb

    International Nuclear Information System (INIS)

    Shoja, M.; Shahbazi, F.

    2012-01-01

    Recent experiment on spin-3/2 bilayer honeycomb lattice antiferromagnet Bi 3 Mn 4 O 12 (NO 3 ) shows a spin liquid behavior down to very low temperatures. This behavior can be ascribed to the frustration effect due to competitions between first and second nearest neighbour's antiferromagnet interaction. Motivated by the experiment, we study J 1 -J 2 Antiferromagnet Heisenberg model, using Mean field Theory. This calculation shows highly degenerate ground state. We also calculate the effect of second nearest neighbor through z direction and show these neighbors also increase frustration in these systems. Because of these degenerate ground state in these systems, spins can't find any ground state to be freeze in low temperatures. This behavior shows a novel spin liquid state down to very low temperatures.

  16. Strongly Coupled Systems: From Quantum Antiferromagnets To Unified Models For Superconductors

    CERN Document Server

    Chudnovsky, V

    2002-01-01

    I discuss the significance of the antiferromagnetic Heisenberg model (AFHM) in both high-energy and condensed-matter physics, and proceed to describe an efficient cluster algorithm used to simulate the AFHM. This is one of two algorithms with which my collaborators and I were able to obtain numerical results that definitively confirm that chiral perturbation theory, corrected for cutoff effects in the AFHM, leads to a correct field-theoretical description of the low- temperature behavior of the spin correlation length in various spin representations S. Using a finite-size-scaling technique, we explored correlation lengths of up to 105 lattice spacings for spins S = 1 and 5/2. We show how the recent prediction of cutoff effects by P. Hasenfratz is approached for moderate correlation lengths, and smoothly connects with other approaches to modeling the AFHM at smaller correlation lengths. I also simulate and discuss classical antiferromagnetic systems with simultaneous SO(M) and SO( N) symmetries, which have bee...

  17. Strongly Coupled Systems From Quantum Antiferromagnets To Unified Models For Superconductors

    CERN Document Server

    Chudnovsky, V

    2002-01-01

    I discuss the significance of the antiferromagnetic Heisenberg model (AFHM) in both high-energy and condensed-matter physics, and proceed to describe an efficient cluster algorithm used to simulate the AFHM. This is one of two algorithms with which my collaborators and I were able to obtain numerical results that definitively confirm that chiral perturbation theory, corrected for cutoff effects in the AFHM, leads to a correct field-theoretical description of the low- temperature behavior of the spin correlation length in various spin representations S. Using a finite-size-scaling technique, we explored correlation lengths of up to 105 lattice spacings for spins S = 1 and 5/2. We show how the recent prediction of cutoff effects by P. Hasenfratz is approached for moderate correlation lengths, and smoothly connects with other approaches to modeling the AFHM at smaller correlation lengths. I also simulate and discuss classical antiferromagnetic systems with simultaneous SO(M) and SO( N) symmetries, which have bee...

  18. Strong Coupling of Microwave Photons to Antiferromagnetic Fluctuations in an Organic Magnet

    Science.gov (United States)

    Mergenthaler, Matthias; Liu, Junjie; Le Roy, Jennifer J.; Ares, Natalia; Thompson, Amber L.; Bogani, Lapo; Luis, Fernando; Blundell, Stephen J.; Lancaster, Tom; Ardavan, Arzhang; Briggs, G. Andrew D.; Leek, Peter J.; Laird, Edward A.

    2017-10-01

    Coupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium radicals and a superconducting microwave resonator is investigated in a circuit quantum electrodynamics (circuit QED) architecture. The crystal exhibits paramagnetic behavior above 4 K, with antiferromagnetic correlations appearing below this temperature, and we demonstrate strong coupling at base temperature. The magnetic resonance acquires a field angle dependence as the crystal is cooled down, indicating anisotropy of the exchange interactions. These results show that multispin modes in organic crystals are suitable for circuit QED, offering a platform for their coherent manipulation. They also utilize the circuit QED architecture as a way to probe spin correlations at low temperature.

  19. Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment

    Science.gov (United States)

    Jeevanesan, Bhilahari; Chandra, Premala; Coleman, Piers; Orth, Peter P.

    2015-10-01

    In an extensive computational experiment, we test Polyakov's conjecture that under certain circumstances an isotropic Heisenberg model can develop algebraic spin correlations. We demonstrate the emergence of a multispin U(1) order parameter in a Heisenberg antiferromagnet on interpenetrating honeycomb and triangular lattices. The correlations of this relative phase angle are observed to decay algebraically at intermediate temperatures in an extended critical phase. Using finite-size scaling we show that both phase transitions are of the Berezinskii-Kosterlitz-Thouless type, and at lower temperatures we find long-range Z6 order.

  20. Measurement of the transverse spin correlation in $Z \\to \\tau^+\\tau^-$ decays

    CERN Document Server

    Abreu, P; Adye, T; Ajinenko, I; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Andersson, P; Andreazza, A; Antilogus, P; Apel, W D; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbi, M S; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Bärring, O; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Belous, K S; Benvenuti, Alberto C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bizouard, M A; Bloch, D; Blume, M; Bonesini, M; Bonivento, W; Booth, P S L; Borgland, A W; Borisov, G; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozovic, I; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cao, F; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Cindro, V; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; Dijkstra, H; Di Ciaccio, Lucia; Di Diodato, A; Djannati, A; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Durand, J D; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fanourakis, G K; Fassouliotis, D; Feindt, Michael; Ferrari, P; Ferrer, A; Fichet, S; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gokieli, R; Golob, B; Gonçalves, P; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Green, C; Grefrath, A; Gris, P; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Günther, M; Guy, J; Hahn, F; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Hilke, Hans Jürgen; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Katsanevas, S; Katsoufis, E C; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Kluit, P M; Knoblauch, D; Köne, B; Kokkinias, P; Konoplyannikov, A K; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leisos, A; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Libby, J; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Mahon, J R; Maio, A; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Merk, M; Meroni, C; Meyer, S; Meyer, W T; Myagkov, A; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Münich, K; Mulders, M; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Némécek, S; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Nikolenko, M; Niss, P; Nomerotski, A; Normand, Ainsley; Novák, M; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Orazi, G; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Pain, R; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernegger, H; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Podobnik, T; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sahr, O; Sajot, G; Salt, J; Sannino, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Serbelloni, L; Shellard, R C; Siegrist, P; Silvestre, R; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sokolov, A; Solovyanov, O; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stampfer, D; Stanescu, C; Stanic, S; Stapnes, Steinar; Stavitski, I; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Tegenfeldt, F; Terranova, F; Thomas, J; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Todorova, S; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Waldner, F; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wlodek, T; Yi, J; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zontar, D; Zucchelli, G C; Zumerle, G

    1997-01-01

    The measurement of the correlation between the transverse spin components of $\\tau^+\\tau^-$ pairs collected during 1992 to 1994 with the DELPHI detector at LEP1 is presented. A value \\begin{center} $C_{TT}$~=~0.87~$\\pm$~0.20~(stat.)~$^{+~0.10}_{-~0.12}$~(syst.) \\end{center} was obtained for the correlation parameter, in agreement with the St1AU LYi,

  1. Spin-resolved correlations in the warm-dense homogeneous electron gas

    Science.gov (United States)

    Arora, Priya; Kumar, Krishan; Moudgil, R. K.

    2017-04-01

    We have studied spin-resolved correlations in the warm-dense homogeneous electron gas by determining the linear density and spin-density response functions, within the dynamical self-consistent mean-field theory of Singwi et al. The calculated spin-resolved pair-correlation function gσσ'(r) is compared with the recent restricted path-integral Monte Carlo (RPIMC) simulations due to Brown et al. [Phys. Rev. Lett. 110, 146405 (2013)], while interaction energy Eint and exchange-correlation free energy Fxc with the RPIMC and very recent ab initio quantum Monte Carlo (QMC) simulations by Dornheim et al. [Phys. Rev. Lett. 117, 156403 (2016)]. g↑↓(r) is found to be in good agreement with the RPIMC data, while a mismatch is seen in g↑↑(r) at small r where it becomes somewhat negative. As an interesting result, it is deduced that a non-monotonic T-dependence of g(0) is driven primarily by g↑↓(0). Our results of Eint and Fxc exhibit an excellent agreement with the QMC study due to Dornheim et al., which deals with the finite-size correction quite accurately. We observe, however, a visible deviation of Eint from the RPIMC data for high densities ( 8% at rs = 1). Further, we have extended our study to the fully spin-polarized phase. Again, with the exception of high density region, we find a good agreement of Eint with the RPIMC data. This points to the need of settling the problem of finite-size correction in the spin-polarized phase also. Interestingly, we also find that the thermal effects tend to oppose spatial localization as well as spin polarization of electrons. Supplementary material in the form of one zip file available from the Journal web page at http://https://doi.org/10.1140/epjb/e2017-70532-y

  2. Dynamical correlation functions of the quadratic coupling spin-Boson model

    Science.gov (United States)

    Zheng, Da-Chuan; Tong, Ning-Hua

    2017-06-01

    The spin-boson model with quadratic coupling is studied using the bosonic numerical renormalization group method. We focus on the dynamical auto-correlation functions {C}O(ω ), with the operator \\hat{O} taken as {\\hat{{{σ }}}}x, {\\hat{{{σ }}}}z, and \\hat{X}, respectively. In the weak-coupling regime α index and X is the boson displacement operator. Close to the spin flip point, the high frequency peak of {C}{{{σ }}x}(ω ) is broadened significantly and the line shape changes qualitatively, showing enhanced dephasing at the spin flip point. Project supported by the National Key Basic Research Program of China (Grant No. 2012CB921704), the National Natural Science Foundation of China (Grant No. 11374362), the Fundamental Research Funds for the Central Universities, China, and the Research Funds of Renmin University of China (Grant No. 15XNLQ03).

  3. Measurement of the $t\\bar{t}$ spin correlations and top quark polarization in dileptonic channel

    CERN Document Server

    Khatiwada, Ajeeta

    2017-01-01

    The degree of top polarization and strength of $t\\bar{t}$ correlation are dependent on production dynamics, decay mechanism, and choice of the observables. At the LHC, measurement of the top polarization and spin correlations in $t\\bar{t}$ production is possible through various observables related to the angular distribution of decay leptons. A measurement of differential distribution provides a precision test of the standard model of particle physics and probes for deviations, which could be a sign of new physics. In particular, the phase space for the super-symmetric partner of the top quark can be constrained. Results from the Compact Muon Solenoid (CMS) collaboration for top quark polarization and spin correlation in the dileptonic channel are reviewed briefly in this proceeding. The measurements are obtained using 19.5 fb$^{-1}$ of data collected in pp collisions at the center-of-mass energy of 8 TeV.

  4. Antiferromagnetic order in hybrid electromagnetic metamaterials

    Science.gov (United States)

    Miroshnichenko, Andrey E.; Filonov, Dmitry; Lukyanchuk, Boris; Kivshar, Yuri

    2017-08-01

    We demonstrate experimentally a new type of order in optical magnetism resembling the staggered structure of spins in antiferromagnetic ordered materials. We study hybrid electromagnetic metasurfaces created by assembling hybrid meta-atoms formed by metallic split-ring resonators and dielectric particles with a high refractive index, both supporting optically-induced magnetic dipole resonances of different origin. Each pair (or ‘metamolecule’) is characterized by two interacting magnetic dipole moments with the distance-dependent magnetization resembling the spin exchange interaction in magnetic materials. By directly mapping the structure of the electromagnetic fields, we demonstrate experimentally that strong coupling between the optically-induced magnetic moments of different origin can flip the magnetisation orientation in a metamolecule creating an antiferromagnetic lattice of staggered optically-induced magnetic moments in hybrid metasurfaces.

  5. Spin correlation tensor for measurement of quantum entanglement in electron-electron scattering

    Science.gov (United States)

    Tsurikov, D. E.; Samarin, S. N.; Williams, J. F.; Artamonov, O. M.

    2017-04-01

    We consider the problem of correct measurement of a quantum entanglement in the two-body electron-electron scattering. An expression is derived for a spin correlation tensor of a pure two-electron state. A geometric measure of a quantum entanglement as the distance between two forms of this tensor in entangled and separable cases is presented. Due to such definition, one does not need to look for the closest separable state to the analyzed state. We prove that introduced measure satisfies properties of a valid entanglement measure: nonnegativity, discriminance, normalization, non-growth under local operations and classical communication. This measure is calculated for a problem of electron-electron scattering. We prove that it does not depend on the azimuthal rotation angle of the second electron spin relative to the first electron spin before scattering. We specify how to find a spin correlation tensor and the related measure of a quantum entanglement in an experiment with electron-electron scattering. Finally, the introduced measure is extended to the mixed states.

  6. Magnetic correlations in a classic Mott system

    International Nuclear Information System (INIS)

    Bao, W.; Broholm, C.; Aeppli, G.; Carter, S.A.; Dai, D.; Frost, C.D.

    1997-07-01

    The metal-insulator transition in V 2 O 3 causes a fundamental change in its magnetism. While the antiferromagnetic insulator (AFI) is a Heisenberg localized spin system, the antiferromagnetism in the strongly correlated metal is determined by a Fermi surface instability. Paramagnetic fluctuations in the metal and insulator represent similar spatial spin correlations, but are unrelated to the long range order in the AFI. The phase transition to the AFI induces an abrupt switching of magnetic correlations to a different magnetic wave vector. The AFI transition, therefore, is not a conventional spin order-disorder transition. Instead it is accounted for by an ordering in the occupation of the two degenerate d-orbitals at the Fermi level

  7. Emergent criticality and Friedan scaling in a two-dimensional frustrated Heisenberg antiferromagnet

    Science.gov (United States)

    Orth, Peter P.; Chandra, Premala; Coleman, Piers; Schmalian, Jörg

    2014-03-01

    We study a two-dimensional frustrated Heisenberg antiferromagnet on the windmill lattice consisting of triangular and dual honeycomb lattice sites. In the classical ground state, the spins on different sublattices are decoupled, but quantum and thermal fluctuations drive the system into a coplanar state via an "order from disorder" mechanism. We obtain the finite temperature phase diagram using renormalization group approaches. In the coplanar regime, the relative U(1) phase between the spins on the two sublattices decouples from the remaining degrees of freedom, and is described by a six-state clock model with an emergent critical phase. At lower temperatures, the system enters a Z6 broken phase with long-range phase correlations. We derive these results by two distinct renormalization group approaches to two-dimensional magnetism: Wilson-Polyakov scaling and Friedan's geometric approach to nonlinear sigma models where the scaling of the spin stiffnesses is governed by the Ricci flow of a 4D metric tensor.

  8. The phase diagrams and the order parameters of the diluted transverse superlattice with antiferromagnetic interface coupling

    International Nuclear Information System (INIS)

    Oubelkacem, A.; El Aouad, N.; Benaboud, A.; Saber, M.

    2004-01-01

    Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions, the magnetic properties of the Ising superlattice consisting of two ferromagnetic materials A and B, with L a layers of diluted spins S a =((1)/(2)) and L b layers of diluted spins S b =1 in an applied transverse field Ω with antiferromagnetic interface coupling are examined. For fixed values of the reduced exchange interactions and the concentration c of magnetic atoms, the phase diagrams and the total magnetization for the superlattice are studied as a function of the transverse field and the temperature. We find a number of characteristic phenomena. In particular, the effect of the concentration c of magnetic atoms, the interlayer coupling and the transverse field on both the compensation temperature and the magnetization profiles are clarified. Some of them may be related to the experimental works of rare-earth (RE)/transition metal (TM) multilayer films

  9. Elucidation of spin echo small angle neutron scattering correlation functions through model studies.

    Science.gov (United States)

    Shew, Chwen-Yang; Chen, Wei-Ren

    2012-02-14

    Several single-modal Debye correlation functions to approximate part of the overall Debey correlation function of liquids are closely examined for elucidating their behavior in the corresponding spin echo small angle neutron scattering (SESANS) correlation functions. We find that the maximum length scale of a Debye correlation function is identical to that of its SESANS correlation function. For discrete Debye correlation functions, the peak of SESANS correlation function emerges at their first discrete point, whereas for continuous Debye correlation functions with greater width, the peak position shifts to a greater value. In both cases, the intensity and shape of the peak of the SESANS correlation function are determined by the width of the Debye correlation functions. Furthermore, we mimic the intramolecular and intermolecular Debye correlation functions of liquids composed of interacting particles based on a simple model to elucidate their competition in the SESANS correlation function. Our calculations show that the first local minimum of a SESANS correlation function can be negative and positive. By adjusting the spatial distribution of the intermolecular Debye function in the model, the calculated SESANS spectra exhibit the profile consistent with that of hard-sphere and sticky-hard-sphere liquids predicted by more sophisticated liquid state theory and computer simulation. © 2012 American Institute of Physics

  10. Quantum discord and quantum phase transition in spin chains

    OpenAIRE

    Dillenschneider, Raoul

    2008-01-01

    Quantum phase transitions of the transverse Ising and antiferromagnetic XXZ spin S=1/2 chains are studied using quantum discord. Quantum discord allows the measure of quantum correlations present in many-body quantum systems. It is shown that the amount of quantum correlations increases close to the critical points. The observations are in agreement with the information provided by the concurrence which measures the entanglement of the many-body system.

  11. Incommensurate correlations in the anisotropic triangular Heisenberg lattice

    Science.gov (United States)

    Weichselbaum, Andreas; White, Steven R.

    2011-12-01

    We study the anisotropic spin-1/2 antiferromagnetic triangular Heisenberg lattice in two dimensions, seen as a set of chains with couplings J (J') along (in-between) chains, respectively. Our focus is on the incommensurate correlation that emerges in this system in a wide parameter range due to the intrinsic frustration of the spins. We study this system with traditional density matrix renormalization group using cylindrical boundary conditions to least constrain possible incommensurate order. Despite that the limit of essentially decoupled chains J'/J≲0.5 is not very accessible numerically, it appears that the spin-spin correlations remain incommensurate for any finite 0JC', where JC'/J>1. The incommensurate wave vector qJ, however, approaches the commensurate value corresponding to the antiferromagnetic correlation of a single chain very rapidly with decreasing J'/J, roughly as qJ˜π-c1(J'/J)ne-c2J/J'.

  12. Correlated spin currents generated by resonant-crossed Andreev reflections in topological superconductors

    Science.gov (United States)

    He, James J.; Wu, Jiansheng; Choy, Ting-Pong; Liu, Xiong-Jun; Tanaka, Y.; Law, K. T.

    2014-01-01

    Topological superconductors, which support Majorana fermion excitations, have been the subject of intense studies due to their novel transport properties and their potential applications in fault-tolerant quantum computations. Here we propose a new type of topological superconductors that can be used as a novel source of correlated spin currents. We show that inducing superconductivity on a AIII class topological insulator wire, which respects a chiral symmetry and supports protected fermionic end states, will result in a topological superconductor. This topological superconductor supports two topological phases with one or two Majorana fermion end states, respectively. In the phase with two Majorana fermions, the superconductor can split Cooper pairs efficiently into electrons in two spatially separated leads due to Majorana-induced resonant-crossed Andreev reflections. The resulting currents in the leads are correlated and spin-polarized. Importantly, the proposed topological superconductors can be realized using quantum anomalous Hall insulators in proximity to superconductors. PMID:24492649

  13. Top Quark Pair Properties - Spin Correlation, Charge Asymmetry, and Complex Final States - at ATLAS

    Directory of Open Access Journals (Sweden)

    Brost Elizabeth

    2014-04-01

    Full Text Available We present measurements of top quark pair properties performed with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s = 7 TeV. The latest measurements of spin correlation and charge asymmetry in tt¯$t\\overline t $ events, as well as measurements of the cross section for tt¯$t\\overline t $ production in association with vector bosons, are presented.

  14. Producing coherent excitations in pumped Mott antiferromagnetic insulators

    Science.gov (United States)

    Wang, Yao; Claassen, Martin; Moritz, B.; Devereaux, T. P.

    2017-12-01

    Nonequilibrium dynamics in correlated materials has attracted attention due to the possibility of characterizing, tuning, and creating complex ordered states. To understand the photoinduced microscopic dynamics, especially the linkage under realistic pump conditions between transient states and remnant elementary excitations, we performed nonperturbative simulations of various time-resolved spectroscopies. We used the Mott antiferromagnetic insulator as a model platform. The transient dynamics of multiparticle excitations can be attributed to the interplay between Floquet virtual states and a modification of the density of states, in which interactions induce a spectral weight transfer. Using an autocorrelation of the time-dependent spectral function, we show that resonance of the virtual states with the upper Hubbard band in the Mott insulator provides the route towards manipulating the electronic distribution and modifying charge and spin excitations. Our results link transient dynamics to the nature of many-body excitations and provide an opportunity to design nonequilibrium states of matter via tuned laser pulses.

  15. Spin-density functional for exchange anisotropic Heisenberg model

    International Nuclear Information System (INIS)

    Prata, G.N.; Penteado, P.H.; Souza, F.C.; Libero, Valter L.

    2009-01-01

    Ground-state energies for antiferromagnetic Heisenberg models with exchange anisotropy are estimated by means of a local-spin approximation made in the context of the density functional theory. Correlation energy is obtained using the non-linear spin-wave theory for homogeneous systems from which the spin functional is built. Although applicable to chains of any size, the results are shown for small number of sites, to exhibit finite-size effects and allow comparison with exact-numerical data from direct diagonalization of small chains.

  16. Ground state properties of a spin chain within Heisenberg model with a single lacking spin site

    International Nuclear Information System (INIS)

    Mebrouki, M.

    2011-01-01

    The ground state and first excited state energies of an antiferromagnetic spin-1/2 chain with and without a single lacking spin site are computed using exact diagonalization method, within the Heisenberg model. In order to keep both parts of a spin chain with a lacking site connected, next nearest neighbors interactions are then introduced. Also, the Density Matrix Renormalization Group (DMRG) method is used, to investigate ground state energies of large system sizes; which permits us to inquire about the effect of large system sizes on energies. Other quantum quantities such as fidelity and correlation functions are also studied and compared in both cases. - Research highlights: → In this paper we compute ground state and first excited state energies of a spin chain with and without a lacking spin site. The next nearest neighbors are introduced with the antiferromagnetic Heisenberg spin-half. → Exact diagonalization is used for small systems, where DMRG method is used to compute energies for large systems. Other quantities like quantum fidelity and correlation are also computed. → Results are presented in figures with comments. → E 0 /N is computed in a function of N for several values of J 2 and for both systems. First excited energies are also investigated.

  17. Evolution of spin correlations in SrDy2O4 in an applied magnetic field

    Science.gov (United States)

    Petrenko, O. A.; Young, O.; Brunt, D.; Balakrishnan, G.; Manuel, P.; Khalyavin, D. D.; Ritter, C.

    2017-03-01

    The development of short- and long-range magnetic order induced in a frustrated zigzag ladder compound SrDy2O4 by an applied field is studied using neutron-diffraction techniques. In zero field, SrDy2O4 lacks long-range magnetic order down to temperatures as low as 60 mK, and the observed powder-neutron-diffraction (PND) patterns are dominated by very broad diffuse scattering peaks. Single-crystal neutron diffraction reveals that the zero-field magnetic structure consists of a collection of antiferromagnetic chains running along the c axis and that there is very little correlation between the chains in the a b plane. In an applied magnetic field, the broad diffuse scattering features in PND are gradually replaced by much sharper peaks, however, the pattern remains rather complex, reflecting the highly anisotropic nature of SrDy2O4 . Single-crystal neutron diffraction shows that a moderate field applied along the b axis induces an up-up-down magnetic order associated with a 1/3 -magnetization plateau, in which magnetic correlation length in the a b plane is significantly increased, but it nevertheless remains finite. The resolution-limited k =0 peaks associated with a ferromagnetic arrangement appear in powder and single-crystal neutron-diffraction patterns in fields of 2.5 T and above.

  18. Investigation of spin correlations in top-pair production with the CMS detector at the LHC

    International Nuclear Information System (INIS)

    Davids, Martina

    2011-01-01

    In spring 2010 the Large Hadron Collider (LHC) started its operation with a center-of-mass energy of 7 TeV, that will be increased up to 14 TeV in the following years. Considering a medium energy of √(s)=10 TeV and a luminosity of L=10 33 cm -2 s -1 some million top quarks are produced per year. This offers the opportunity to investigate spin-correlations between the top quarks from pair production. As the spinconfiguration of the top-quark pair depends on the production mechanism, a measurement of such effects is a unique tool to study the contributions of the production processes and spin effects. This allows to test the Standard Model. This thesis investigates dileptonic top-pair decays at the Compact Muon Solenoid based on simulated events. A quantitative measure of spin correlations is the asymmetry A, that manifests itself in the angular distribution of the two leptons. A full kinematic reconstruction of the top pair is necessary to determine this distribution. The MC generators Pythia, MC rate at NLO, and TopReX are tested with respect to their treatment of spin-correlations. Pythia is used to generate uncorrelated samples. MC rate at NLO reproduces the Standard Model prediction. These samples are used to determine the sensitivity of the present analysis. Due to an incorrect implementation of the helicity states, TopReX is not usable. A full event selection and reconstruction are adapted. The reconstructed angular distribution shows a significant distortion. A template method is implemented to determine the asymmetry. Here, the angular distribution is decomposed into a flat, a completely asymmetric, and a background part, that are fitted by a binned χ 2 approach to toy-data. An ensemble study is performed to estimate the statistical uncertainty. As the main systematic uncertainties, generator effects, the jet energy scale and uncertainties in the cross sections or selection efficiency are investigated. Considering an integrated luminosity of L int =1 fb

  19. Calculations of Exchange Bias in Thin Films with Ferromagnetic/Antiferromagnetic Interfaces

    Science.gov (United States)

    Koon, N. C.

    1997-06-01

    A microscopic explanation of exchange bias in thin films with compensated ferro/antiferromagnetic interfaces is presented. Full micromagnetic calculations show the interfacial exchange coupling to be relatively strong with a perpendicular orientation between the ferro/antiferromagnetic axis directions, similar to the classic ``spin-flop'' state in bulk antiferromagnets. With reasonable parameters the calculations predict bias fields comparable to those observed and provide a possible explanation for both anomalous high field rotational hysteresis and recently discovered ``positive'' exchange bias.

  20. Charge dynamics of the antiferromagnetically ordered Mott insulator

    International Nuclear Information System (INIS)

    Han, Xing-Jie; Li, Xin; Chen, Jing; Liao, Hai-Jun; Xiang, Tao; Liu, Yu; Liu, Zhi-Yuan; Xie, Zhi-Yuan; Normand, B

    2016-01-01

    We introduce a slave-fermion formulation in which to study the charge dynamics of the half-filled Hubbard model on the square lattice. In this description, the charge degrees of freedom are represented by fermionic holons and doublons and the Mott-insulating characteristics of the ground state are the consequence of holon–doublon bound-state formation. The bosonic spin degrees of freedom are described by the antiferromagnetic Heisenberg model, yielding long-ranged (Néel) magnetic order at zero temperature. Within this framework and in the self-consistent Born approximation, we perform systematic calculations of the average double occupancy, the electronic density of states, the spectral function and the optical conductivity. Qualitatively, our method reproduces the lower and upper Hubbard bands, the spectral-weight transfer into a coherent quasiparticle band at their lower edges and the renormalisation of the Mott gap, which is associated with holon–doublon binding, due to the interactions of both quasiparticle species with the magnons. The zeros of the Green function at the chemical potential give the Luttinger volume, the poles of the self-energy reflect the underlying quasiparticle dispersion with a spin-renormalised hopping parameter and the optical gap is directly related to the Mott gap. Quantitatively, the square-lattice Hubbard model is one of the best-characterised problems in correlated condensed matter and many numerical calculations, all with different strengths and weaknesses, exist with which to benchmark our approach. From the semi-quantitative accuracy of our results for all but the weakest interaction strengths, we conclude that a self-consistent treatment of the spin-fluctuation effects on the charge degrees of freedom captures all the essential physics of the antiferromagnetic Mott–Hubbard insulator. We remark in addition that an analytical approximation with these properties serves a vital function in developing a full understanding of

  1. Charge dynamics of the antiferromagnetically ordered Mott insulator

    Science.gov (United States)

    Han, Xing-Jie; Liu, Yu; Liu, Zhi-Yuan; Li, Xin; Chen, Jing; Liao, Hai-Jun; Xie, Zhi-Yuan; Normand, B.; Xiang, Tao

    2016-10-01

    We introduce a slave-fermion formulation in which to study the charge dynamics of the half-filled Hubbard model on the square lattice. In this description, the charge degrees of freedom are represented by fermionic holons and doublons and the Mott-insulating characteristics of the ground state are the consequence of holon-doublon bound-state formation. The bosonic spin degrees of freedom are described by the antiferromagnetic Heisenberg model, yielding long-ranged (Néel) magnetic order at zero temperature. Within this framework and in the self-consistent Born approximation, we perform systematic calculations of the average double occupancy, the electronic density of states, the spectral function and the optical conductivity. Qualitatively, our method reproduces the lower and upper Hubbard bands, the spectral-weight transfer into a coherent quasiparticle band at their lower edges and the renormalisation of the Mott gap, which is associated with holon-doublon binding, due to the interactions of both quasiparticle species with the magnons. The zeros of the Green function at the chemical potential give the Luttinger volume, the poles of the self-energy reflect the underlying quasiparticle dispersion with a spin-renormalised hopping parameter and the optical gap is directly related to the Mott gap. Quantitatively, the square-lattice Hubbard model is one of the best-characterised problems in correlated condensed matter and many numerical calculations, all with different strengths and weaknesses, exist with which to benchmark our approach. From the semi-quantitative accuracy of our results for all but the weakest interaction strengths, we conclude that a self-consistent treatment of the spin-fluctuation effects on the charge degrees of freedom captures all the essential physics of the antiferromagnetic Mott-Hubbard insulator. We remark in addition that an analytical approximation with these properties serves a vital function in developing a full understanding of the

  2. Polyakov loop and spin correlators on finite lattices. A study beyond the mass gap

    International Nuclear Information System (INIS)

    Engels, J.; Neuhaus, T.

    1995-01-01

    We derive an analytic expression for point-to-point correlation functions of the Polyakov loop based on the transfer matrix formalism. For the 2D Ising model we show that the results deduced from point-point spin correlators are coinciding with those from zero momentum correlators. We investigate the contributions from eigenvalues of the transfer matrix beyond the mass gap and discuss the limitations and possibilities of such an analysis. The finite size behaviour of the obtained 2D Ising model matrix elements is examined. The point-to-point correlator formula is then applied to Polyakov loop data in finite temperature SU(2) gauge theory. The leading matrix element shows all expected scaling properties. Just above the critical point we find a Debye screening mass μ D /T∼4, independent of the volume. ((orig.))

  3. Spin-orbit and electron correlation effects on the structure of EF3 (E = I, At, and element 117).

    Science.gov (United States)

    Kim, Hyoseok; Choi, Yoon Jeong; Lee, Yoon Sup

    2008-12-18

    Structures and vibrational frequencies of group 17 fluorides EF3 (E = I, At, and element 117) are calculated at the density functional theory (DFT) level of theory using relativistic effective core potentials (RECPs) with and without spin-orbit terms in order to investigate the effects of spin-orbit interactions and electron correlations on the structures and vibrational frequencies of EF3. Various tests imply that spin-orbit and electron correlation effects estimated presently from Hartree-Fock (HF) and DFT calculations with RECPs with and without spin-orbit terms are quite reasonable. Spin-orbit and electron correlation effects generally increase bond lengths and/or angles in both C2v and D3h structures. For IF3, the C2v structure is a global minimum, and the D3h structure is a second-order saddle point in both HF and DFT calculations with and without spin-orbit interactions. Spin-orbit effects for IF3 are negligible in comparison to electron correlation effects. The D3h global minimum is the only minimum structure for (117)F3 in all RECP calculations, and the C2v structure is neither a local minimum nor a saddle point. In the case of AtF3, the C2v structure is found to be a local minimum in all RECP calculations without spin-orbit terms, and the D3h structure becomes a local minimum at the DFT level of theory with and without spin-orbit interactions. In the HF calculation with spin-orbit terms, the D3h structure of AtF3 is a second-order saddle point. AtF3 is a borderline case between the valence-shell-electron-pair-repulsion (VSEPR) structure of IF3 and the non-VSEPR structure of (117)F3. Relativistic effects, including scalar relativistic and spin-orbit effects, and electron correlation effects together or separately stabilize the D3h structures more than the C2v structures. As a result, one may suggest that the VSEPR predictions agree very well with the structures optimized by the nonrelativistic HF level of theory even for heavy-atom molecules but not so

  4. Enhanced exchange bias fields for CoO/Co bilayers: influence of antiferromagnetic grains and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Cheng-Hsun-Tony; Chang, Shin-Chen [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Tsay, Jyh-Shen, E-mail: jstsay@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Yao, Yeong-Der [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

    2017-05-31

    Highlights: • An antiferromagnetic grain model on exchange bias phenomena is proposed. • Grain size and grain density are considered. • For smaller grain size, the dependence of t{sub CoO} on T{sub B} showed a less pronounced variation. • An increased grain density is responsible for the enhancement in the exchange bias fields. - Abstract: The emergence and optimization of devices that can be applied to spintronics have attracted considerable interest, and both experimental and theoretical approaches have been used in studies of exchange bias phenomena. A survey of the literature indicates that great efforts have been devoted to improving exchange bias fields, while only limited attempts have been made to control the temperature dependence of exchange bias. In this study, the influence of antiferromagnetic grains on exchange bias phenomena in CoO/Co bilayers on a semiconductor surface was investigated. Based on an antiferromagnetic grain model, a correlation between grain size, grain density, blocking temperature, and the exchange bias field was established. For crystallites with a smaller median diameter, the dependence of the thickness of the CoO layer on blocking temperature showed a less pronounced variation. This is due to the larger thermal agitation of the atomic spin moments in the grain, which causes a weaker exchange coupling between atomic spin moments. The enhanced density of antiferromagnetic/ferromagnetic pinning sites resulting from an increased grain density is responsible for the enhancement in the exchange bias fields. The results reported herein provide insights into our knowledge related to controlling the temperature dependence of exchange bias and related mechanisms.

  5. Measurement of the neutrino-spin correlation parameter B neutron decay using ultracold neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Wilburn, Wesley S [Los Alamos National Laboratory

    2009-01-01

    We present a new approach to measuring the neutrino-spin correlation parameter B in neutron decay. The approach combines the technology of large-area ion-implanted silicon detectors being developed for the abBA experiment, with an ultracold neutron source to provide more precise neutron polarimetry. The technique detects both proton and electron from the neutron decay in coincidence. B is determined from an electron-energy-dependent measurement of the proton spin asymmetry. This approach will provide a statistical precision of 1 x 10-4 . The systematic precision is still being evaluated, but is expected to be below 1 x 10-3 , and could approach 1 x 10-4 . A measurement of B with this precision would place constraints on supersymmetric extensions to the Standard Model.

  6. Quantum correlations in a system of nuclear s = 1/2 spins in a strong magnetic field

    International Nuclear Information System (INIS)

    Fel’dman, E B; Kuznetsova, E I; Yurishchev, M A

    2012-01-01

    Entanglement and quantum discord for a pair of nuclear spins s = 1/2 in a nanopore filled with a gas of spin-carrying molecules (atoms) are studied. The correlation functions describing dynamics of dipolar-coupled spins in a nanopore are found. The dependence of spin-pair entanglement on the temperature and the number of spins is obtained from the reduced density matrix, which is centrosymmetric (CS). An analytic expression for the concurrence is obtained for an arbitrary CS density matrix. It is shown that the quantum discord as a measure of quantum correlations attains a significant value at low temperatures. It is also shown that the discord in the considered model has ‘flickering’ character and disappears periodically in the course of time evolution of the system. The geometric discord is studied for arbitrary 4 × 4 CS density matrices. (paper)

  7. A statistical correlation investigation for the role of surface spins to the spin relaxation of nitrogen vacancy centers

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xuerui; Zhang, Jian; Feng, Fupan; Wang, Junfeng; Zhang, Wenlong; Lou, Liren; Zhu, Wei; Wang, Guanzhong, E-mail: gzwang@ustc.edu.cn [Hefei National Laboratory for Physical Science at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026 (China)

    2014-04-15

    We investigated the influence of spins on surface of nanodiamonds (NDs) to the longitudinal relaxation time (T{sub 1}) and transverse relaxation time (T{sub 2}) of nitrogen vacancy (NV) centers in ND. A spherical model of the NDs was suggested to account for the experimental results of T{sub 1} and T{sub 2}, and the density of surface spins was roughly estimated based on the statistical analysis of experimental results of 72 NDs containing a single NV center. For NDs studied here, the T{sub 1} of NV center inside is highly dependent to the surface spins of the NDs. However, for the T{sub 2} of NV center, intrinsic contributions must be much pronounced than that by surface spins. In other words, T{sub 1} of an NV center in NDs is more sensitive to the change of the surface spin density than T{sub 2}.

  8. A statistical correlation investigation for the role of surface spins to the spin relaxation of nitrogen vacancy centers

    Directory of Open Access Journals (Sweden)

    Xuerui Song

    2014-04-01

    Full Text Available We investigated the influence of spins on surface of nanodiamonds (NDs to the longitudinal relaxation time (T1 and transverse relaxation time (T2 of nitrogen vacancy (NV centers in ND. A spherical model of the NDs was suggested to account for the experimental results of T1 and T2, and the density of surface spins was roughly estimated based on the statistical analysis of experimental results of 72 NDs containing a single NV center. For NDs studied here, the T1 of NV center inside is highly dependent to the surface spins of the NDs. However, for the T2 of NV center, intrinsic contributions must be much pronounced than that by surface spins. In other words, T1 of an NV center in NDs is more sensitive to the change of the surface spin density than T2.

  9. Magnonic topological insulators in antiferromagnets

    Science.gov (United States)

    Nakata, Kouki; Kim, Se Kwon; Klinovaja, Jelena; Loss, Daniel

    2017-12-01

    Extending the notion of symmetry protected topological phases to insulating antiferromagnets (AFs) described in terms of opposite magnetic dipole moments associated with the magnetic N e ´el order, we establish a bosonic counterpart of topological insulators in semiconductors. Making use of the Aharonov-Casher effect, induced by electric field gradients, we propose a magnonic analog of the quantum spin Hall effect (magnonic QSHE) for edge states that carry helical magnons. We show that such up and down magnons form the same Landau levels and perform cyclotron motion with the same frequency but propagate in opposite direction. The insulating AF becomes characterized by a topological Z2 number consisting of the Chern integer associated with each helical magnon edge state. Focusing on the topological Hall phase for magnons, we study bulk magnon effects such as magnonic spin, thermal, Nernst, and Ettinghausen effects, as well as the thermomagnetic properties of helical magnon transport both in topologically trivial and nontrivial bulk AFs and establish the magnonic Wiedemann-Franz law. We show that our predictions are within experimental reach with current device and measurement techniques.

  10. Virtual-site correlation mean field approach to criticality in spin systems

    International Nuclear Information System (INIS)

    Sen, Aditi; Sen, Ujjwal

    2013-01-01

    We propose a virtual-site correlation mean field theory for dealing with interacting many-body systems. It involves a coarse-graining technique that terminates a step before the mean field theory: While mean field theory deals with only single-body physical parameters, the virtual-site correlation mean field theory deals with single- as well as two-body ones, and involves a virtual site for every interaction term in the Hamiltonian. We generalize the theory to a cluster virtual-site correlation mean field, that works with a fundamental unit of the lattice of the many-body system. We apply these methods to interacting Ising spin systems in several lattice geometries and dimensions, and show that the predictions of the onset of criticality of these models are generally much better in the proposed theories as compared to the corresponding ones in mean field theories

  11. The role of three-gluon correlation functions in the single spin asymmetry

    Directory of Open Access Journals (Sweden)

    Beppu Hiroo

    2015-01-01

    Full Text Available We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the asymmetry at the RHIC energy, using a model for the three-gluon correlation functions suggested by the asymmetry for the D-meson production at RHIC. We found that the asymmetries for the light-hadron and the jet productions are very useful to constrain the magnitude and form of the correlation functions. Since the three-gluon correlation functions shift the asymmetry for all kinds of hadrons in the same direction, it is unlikely that they become a main source of the asymmetry.

  12. Pairwise correlations via quantum discord and its geometric measure in a four-qubit spin chain

    Directory of Open Access Journals (Sweden)

    Abdel-Baset A. Mohamed

    2013-04-01

    Full Text Available The dynamic of pairwise correlations, including quantum entanglement (QE and discord (QD with geometric measure of quantum discord (GMQD, are shown in the four-qubit Heisenberg XX spin chain. The results show that the effect of the entanglement degree of the initial state on the pairwise correlations is stronger for alternate qubits than it is for nearest-neighbor qubits. This parameter results in sudden death for QE, but it cannot do so for QD and GMQD. With different values for this entanglement parameter of the initial state, QD and GMQD differ and are sensitive for any change in this parameter. It is found that GMQD is more robust than both QD and QE to describe correlations with nonzero values, which offers a valuable resource for quantum computation.

  13. Interplay of spin-orbit coupling and superconducting correlations in germanium telluride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Vijay; Nguyen, Thuy-Anh; Mansell, Rhodri; Ritchie, David [Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE (United Kingdom); Mussler, Gregor [Peter Gruenberg Institute (PGI-9), Forschungszentrum Juelich, 52425, Juelich (Germany)

    2016-03-15

    There is much current interest in combining superconductivity and spin-orbit coupling in order to induce the topological superconductor phase and associated Majorana-like quasiparticles which hold great promise towards fault-tolerant quantum computing. Experimentally these effects have been combined by the proximity-coupling of super-conducting leads and high spin-orbit materials such as InSb and InAs, or by controlled Cu-doping of topological insu-lators such as Bi{sub 2}Se{sub 3}. However, for practical purposes, a single-phase material which intrinsically displays both these effects is highly desirable. Here we demonstrate coexisting superconducting correlations and spin-orbit coupling in molecular-beam-epitaxy-grown thin films of GeTe. The former is evidenced by a precipitous low-temperature drop in the electrical resistivity which is quelled by a magnetic field, and the latter manifests as a weak antilocalisation (WAL) cusp in the magnetotransport. Our studies reveal several other intriguing features such as the presence of two-dimensional rather than bulk transport channels below 2 K, possible signatures of topological superconductivity, and unexpected hysteresis in the magnetotransport. Our work demonstrates GeTe to be a potential host of topological SC and Majorana-like excitations, and to be a versatile platform to develop quantum information device architectures. (copyright 2016 The Authors. Phys. Status Solidi RRL published by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Quantum correlation dynamics subjected to critical spin environment with short-range anisotropic interaction.

    Science.gov (United States)

    Guo, J L; Zhang, X Z

    2016-09-06

    Short-range interaction among the spins can not only results in the rich phase diagram but also brings about fascinating phenomenon both in the contexts of quantum computing and information. In this paper, we investigate the quantum correlation of the system coupled to a surrounding environment with short-range anisotropic interaction. It is shown that the decay of quantum correlation of the central spins measured by pairwise entanglement and quantum discord can serve as a signature of quantum phase transition. In addition, we study the decoherence factor of the system when the environment is in the vicinity of the phase transition point. In the strong coupling regime, the decay of the decoherence factor exhibits Gaussian envelop in the time domain. However, in weak coupling limit, the quantum correlation of the system is robust against the disturbance of the magnetic field through optimal control of the anisotropic short-range interaction strength. Based on this, the effects of the short-range anisotropic interaction on the sudden transition from classical to quantum decoherence are also presented.

  15. Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs

    Science.gov (United States)

    Edén, Mattias

    2010-05-01

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t2 domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t1) dimension. We employ experimental 23Na and 27Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl2O5), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations.

  16. A general explanation on the correlation of dark matter halo spin with the large-scale environment

    Science.gov (United States)

    Wang, Peng; Kang, Xi

    2017-06-01

    Both simulations and observations have found that the spin of halo/galaxy is correlated with the large-scale environment, and particularly the spin of halo flips in filament. A consistent picture of halo spin evolution in different environments is still lacked. Using N-body simulation, we find that halo spin with its environment evolves continuously from sheet to cluster, and the flip of halo spin happens both in filament and nodes. The flip in filament can be explained by halo formation time and migrating time when its environment changes from sheet to filament. For low-mass haloes, they form first in sheets and migrate into filaments later, so their mass and spin growth inside filament are lower, and the original spin is still parallel to filament. For high-mass haloes, they migrate into filaments first, and most of their mass and spin growth are obtained in filaments, so the resulted spin is perpendicular to filament. Our results well explain the overall evolution of cosmic web in the cold dark matter model and can be tested using high-redshift data. The scenario can also be tested against alternative models of dark matter, such as warm/hot dark matter, where the structure formation will proceed in a different way.

  17. Thermal Phase Transitions of Strongly Correlated Bosons with Spin-Orbit Coupling

    Science.gov (United States)

    Hickey, Ciarán; Paramekanti, Arun

    2014-12-01

    Experiments on ultracold atoms have started to explore lattice effects and thermal fluctuations for two-component bosons with spin-orbit coupling (SOC). Motivated by this, we derive and study a t J model for lattice bosons with equal Rashba-Dresselhaus SOC and strong Hubbard repulsion in a uniform Zeeman magnetic field. Using the Gutzwiller ansatz, we find strongly correlated ground states with stripe superfluid (SF) order. We formulate a finite temperature generalization of the Gutzwiller method, and show that thermal fluctuations in the doped Mott insulator drive a two-step melting of the stripe SF, revealing a wide regime of a stripe normal fluid.

  18. Nanoparticles of antiferromagnetic materials

    DEFF Research Database (Denmark)

    Madsen, Daniel Esmarch

    2008-01-01

    I denne Ph.D. afhandling studeres forskellige egenskaber ved antiferromagnetiske nanopartikler. I en ideel antiferromagnet er spinnene orienteret således at der ikke er et resulterende magnetisk moment. I nanopartikler af antiferromagnetiske materialer er denne kompensation på grund af forskellig...

  19. Prospect for antiferromagnetic spintronics

    Czech Academy of Sciences Publication Activity Database

    Martí, Xavier; Fina, I.; Jungwirth, Tomáš

    2015-01-01

    Roč. 51, č. 4 (2015), s. 2900104 ISSN 0018-9464 R&D Projects: GA MŠk(CZ) LM2011026; GA ČR GB14-37427G EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.277, year: 2015

  20. Synthetic antiferromagnetic spintronics

    Science.gov (United States)

    Duine, R. A.; Lee, Kyung-Jin; Parkin, Stuart S. P.; Stiles, M. D.

    2018-03-01

    Spintronic and nanomagnetic devices often derive their functionality from layers of different materials and the interfaces between them. We discuss the opportunities that arise from synthetic antiferromagnets consisting of two or more ferromagnetic layers that are separated by metallic spacers or tunnel barriers and have antiparallel magnetizations.

  1. Translationally invariant treatment of pair correlations in nuclei: I. Spin and isospin dependent correlations

    Energy Technology Data Exchange (ETDEWEB)

    Guardiola, R. [Valencia Univ., Burjassot (Spain). Dept. de Fisica Atomica, Molecular y Nucl.; Moliner, P.I. [Valencia Univ., Burjassot (Spain). Dept. de Fisica Atomica, Molecular y Nucl.; Navarro, J. [IFIC (Centre Mixt CSIC -Universitat de Valencia), Avda. Dr. Moliner 50, E-46100 Burjassot (Spain); Bishop, R.F. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Puente, A. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Walet, N.R. [Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom)

    1996-11-11

    We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation operators. Our techniques are tailored to those nuclei that can be dealt with in LS coupling, which includes all nuclei up to the shell closure at A=40. We study mainly p-shell nuclei in this paper. A detailed comparison with other microscopic many-body approaches is made, using a variety of schematic nuclear interactions. It is shown that our methodology produces very good energies, and presumably also wave functions, for medium mass nuclei. (orig.).

  2. Spin-polarized current in noncollinear antiferromagnets

    Czech Academy of Sciences Publication Activity Database

    Železný, Jakub; Zhang, Y.; Felser, C.; Yan, B.

    2017-01-01

    Roč. 119, č. 18 (2017), s. 1-7, č. článku 187204. ISSN 0031-9007 Institutional support: RVO:68378271 Keywords : anisotropic magnetoresistance * wannier functions * room-temperature * torques * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 8.462, year: 2016

  3. Investigation of the chiral antiferromagnetic Heisenberg model using projected entangled pair states

    Science.gov (United States)

    Poilblanc, Didier

    2017-09-01

    A simple spin-1/2 frustrated antiferromagnetic Heisenberg model (AFHM) on the square lattice—including chiral plaquette cyclic terms—was argued [A. E. B. Nielsen, G. Sierra, and J. I. Cirac, Nat. Commun. 4, 2864 (2013), 10.1038/ncomms3864] to host a bosonic Kalmeyer-Laughlin (KL) fractional quantum Hall ground state [V. Kalmeyer and R. B. Laughlin, Phys. Rev. Lett. 59, 2095 (1987), 10.1103/PhysRevLett.59.2095]. Here, we construct generic families of chiral projected entangled pair states (chiral PEPS) with low bond dimension (D =3 ,4 ,5 ) which, upon optimization, provide better variational energies than the KL Ansatz. The optimal D =3 PEPS exhibits chiral edge modes described by the Wess-Zumino-Witten SU(2) 1 model, as expected for the KL spin liquid. However, we find evidence that, in contrast to the KL state, the PEPS spin liquids have power-law dimer-dimer correlations and exhibit a gossamer long-range tail in the spin-spin correlations. We conjecture that these features are genuine to local chiral AFHM on bipartite lattices.

  4. Is gadolinium a helical antiferromagnet or a collinear ferromagnet?

    Indian Academy of Sciences (India)

    as low as 15 Oe suffice to transform the helical antiferromagnetism into collinear ferro- magnetism. This picture of the spin structure in Gd had to be discarded after subsequent. £Article presented at the International Symposium on Advances in Superconductivity and Mag- netism: Materials, Mechanisms and Devices, ...

  5. Observation of Antiferromagnetic Resonance in an Organic Superconductor

    DEFF Research Database (Denmark)

    Torrance, J. B.; Pedersen, H. J.; Bechgaard, K.

    1982-01-01

    Anomalous microwave absorption has been observed in the organic superconductor TMTSF2AsF6 (TMTSF: tetramethyltetraselenafulvalene) below its metal-nonmetal transition near 12 K. This absorption is unambiguously identified as antiferromagnetic resonance by the excellent agreement between a spin...

  6. Monopoles in an Antiferromagnetic Bose-Einstein Condensate

    NARCIS (Netherlands)

    Stoof, H.T.C.; Vliegen, E.; Al Khawaja, U.

    2001-01-01

    We show that even in three dimensions an antiferromagnetic spin-1 Bose-Einstein condensate, which can, for instance, be created with 23Na atoms in an optical trap, has not only singular linelike vortex excitations, but also allows for singular pointlike topological excitations, i.e., monopoles

  7. Entanglement in correlated random spin chains, RNA folding and kinetic roughening

    International Nuclear Information System (INIS)

    Rodríguez-Laguna, Javier; Santalla, Silvia N; Ramírez, Giovanni; Sierra, Germán

    2016-01-01

    Average block entanglement in the 1D XX-model with uncorrelated random couplings is known to grow as the logarithm of the block size, in similarity to conformal systems. In this work we study random spin chains whose couplings present long range correlations, generated as gaussian fields with a power-law spectral function. Ground states are always planar valence bond states, and their statistical ensembles are characterized in terms of their block entropy and their bond-length distribution, which follow power-laws. We conjecture the existence of a critical value for the spectral exponent, below which the system behavior is identical to the case of uncorrelated couplings. Above that critical value, the entanglement entropy violates the area law and grows as a power law of the block size, with an exponent which increases from zero to one. Interestingly, we show that XXZ models with positive anisotropy present the opposite behavior, and strong correlations in the couplings lead to lower entropies. Similar planar bond structures are also found in statistical models of RNA folding and kinetic roughening, and we trace an analogy between them and quantum valence bond states. Using an inverse renormalization procedure we determine the optimal spin-chain couplings which give rise to a given planar bond structure, and study the statistical properties of the couplings whose bond structures mimic those found in RNA folding. (paper)

  8. Correlation between vestibular and autonomous function after 6 months of spaceflight: Data of the SPIN and GAZE-SPIN experiments.

    Science.gov (United States)

    Wuyts, Floris; Clement, Gilles; Naumov, Ivan; Kornilova, Ludmila; Glukhikh, Dmitriy; Hallgren, Emma; MacDougall, Hamish; Migeotte, Pierre-Francois; Delière, Quentin; Weerts, Aurelie; Moore, Steven; Diedrich, Andre

    In 13 cosmonauts, the vestibulo-autonomic reflex was investigated before and after 6 months duration spaceflight. Cosmonauts were rotated on the mini-centrifuge VVIS, which is installed in Star City. Initially, this mini-centrifuge flew on board of the Neurolab mission (STS-90), and served to generate intermittent artificial gravity during that mission, with apparent very positive effects on the preservation of the orthostatic tolerance upon return to earth in the 4 crew members that were subjected to the rotations in space. The current experiments SPIN and GAZE-SPIN are control experiments to test the hypothesis that intermittent artificial gravity in space can serve as a counter measure against several deleterious effects of microgravity. Additionally, the effect of microgravity on the gaze holding system is studied as well. Cosmonauts from a long duration stay in the International Space Station were tested on the VVIS (1 g centripetal interaural acceleration; consecutive right-ear-out anti-clockwise and left-ear-out clockwise measurement) on 5 different days. Two measurements were scheduled about one month and a half prior to launch and the remaining three immediately after their return from space (typically on R+2, R+4, R+9; R = return day from space). The ocular counter roll (OCR) as a measure of otolith function was measured on before, during and after the rotation in the mini centrifuge, using infrared video goggles. The perception of verticality was monitored using an ultrasound system. Gaze holding was tested before, during and after rotation. After the centrifugation part, the crew was installed on a tilt table, and instrumented with several cardiovascular recording equipment (ECG, continuous blood pressure monitoring, respiratory monitoring), as well as with impedance measurement devices to investigate fluid redistribution throughout the operational tilt test. To measure heart rate variability parameters, imposed breathing periods were included in the

  9. Untersuchung der magnetischen und strukturellen Eigenschaften der beiden niedrigdimensionalen Antiferromagnete TiPO4 und CrOCl

    OpenAIRE

    Reuvekamp, Patrick Gerald

    2014-01-01

    Titanium (III) phosphate TiPO4 (3d1 electronic configuration with S = 1/2) is a one-dimensional quantum antiferromagnet exhibiting non-conventional spin-Peierls behaviour at low temperatures. Chromium oxychloride CrOCl (3d3 electronic configuration with S = 3/2) is a two-dimensional antiferromagnet consisting of ferromagnetic spin chains interconnected by competing anti and ferromagnetic spin exchanges interactions. The magnetic and the structural properties of these compounds are intimately ...

  10. Walls, anomalies, and deconfinement in quantum antiferromagnets

    Science.gov (United States)

    Komargodski, Zohar; Sulejmanpasic, Tin; Ünsal, Mithat

    2018-02-01

    We consider the Abelian-Higgs model in 2 +1 dimensions with instanton-monopole defects. This model is closely related to the phases of quantum antiferromagnets. In the presence of Z2 preserving monopole operators, there are two confining ground states in the monopole phase, corresponding to the valence bond solid (VBS) phase of quantum magnets. We show that the domain wall carries a 't Hooft anomaly in this case. The anomaly can be saturated by, e.g., charge-conjugation breaking on the wall or by the domain wall theory becoming gapless (a gapless model that saturates the anomaly is S U (2) 1 WZW). Either way the fundamental scalar particles (i.e., spinons) which are confined in the bulk are deconfined on the domain wall. This Z2 phase can be realized either with spin-1/2 on a rectangular lattice or spin-1 on a square lattice. In both cases the domain wall contains spin-1/2 particles (which are absent in the bulk). We discuss the possible relation to recent lattice simulations of domain walls in VBS. We further generalize the discussion to Abrikosov-Nielsen-Olsen (ANO) vortices in a dual superconductor of the Abelian-Higgs model in 3 +1 dimensions and to the easy-plane limit of antiferromagnets. In the latter case the wall can undergo a variant of the BKT transition (consistent with the anomalies) while the bulk is still gapped. The same is true for the easy-axis limit of antiferromagnets. We also touch upon some analogies to Yang-Mills theory.

  11. Simplifying the complex 1H NMR spectra of fluorine-substituted benzamides by spin system filtering and spin-state selection: multiple-quantum-single-quantum correlation.

    Science.gov (United States)

    Baishya, Bikash; Reddy, G N Manjunatha; Prabhu, Uday Ramesh; Row, T N Guru; Suryaprakash, N

    2008-10-23

    The proton NMR spectra of fluorine-substituted benzamides are very complex (Figure 1) due to severe overlap of (1)H resonances from the two aromatic rings, in addition to several short and long-range scalar couplings experienced by each proton. With no detectable scalar couplings between the inter-ring spins, the (1)H NMR spectra can be construed as an overlap of spectra from two independent phenyl rings. In the present study we demonstrate that it is possible to separate the individual spectrum for each aromatic ring by spin system filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spin-state selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes.

  12. Correlated displacement-T2 MRI by means of a pulsed field gradient - milti spin echo method

    NARCIS (Netherlands)

    Windt, C.W.; Vergeldt, F.J.; As, van H.

    2007-01-01

    A method for correlated displacement-T2 imaging is presented. A Pulsed Field Gradient-Multi Spin Echo (PFG-MSE) sequence is used to record T2 resolved propagators on a voxel-by-voxel basis, making it possible to perform single voxel correlated displacement-T2 analyses. In spatially heterogeneous

  13. Short-range magnetic correlations and spin dynamics in the paramagnetic regime of (Mn,Fe)2(P,Si)

    NARCIS (Netherlands)

    Miao, X.F.; Caron, L.; Cedervall, J.; Gubbens, P.C.M.; Dalmas de Réotier, P; Yaouanc, A; Qian, F.; Wildes, A. R.; Luetkens, H.; Amato, A; van Dijk, N.H.; Brück, E.H.

    2016-01-01

    The spatial and temporal correlations of magnetic moments in the paramagnetic regime of (Mn,Fe)2(P,Si) have been investigated by means of polarized neutron diffraction and muon-spin relaxation techniques. Short-range magnetic correlations are present at temperatures far above the ferromagnetic

  14. Concepts of antiferromagnetic spintronics

    Czech Academy of Sciences Publication Activity Database

    Gomonay, O.; Jungwirth, Tomáš; Sinova, Jairo

    2017-01-01

    Roč. 11, č. 4 (2017), 1-8, č. článku 1700022. ISSN 1862-6254 R&D Projects: GA MŠk LM2015087; GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.032, year: 2016

  15. Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn.

    Science.gov (United States)

    Galceran, R; Fina, I; Cisneros-Fernández, J; Bozzo, B; Frontera, C; López-Mir, L; Deniz, H; Park, K-W; Park, B-G; Balcells, Ll; Martí, X; Jungwirth, T; Martínez, B

    2016-10-20

    Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.

  16. Relativistic Néel-Order Fields Induced by Electrical Current in Antiferromagnets

    KAUST Repository

    Železný, J.

    2014-10-06

    We predict that a lateral electrical current in antiferromagnets can induce nonequilibrium Néel-order fields, i.e., fields whose sign alternates between the spin sublattices, which can trigger ultrafast spin-axis reorientation. Based on microscopic transport theory calculations we identify staggered current-induced fields analogous to the intraband and to the intrinsic interband spin-orbit fields previously reported in ferromagnets with a broken inversion-symmetry crystal. To illustrate their rich physics and utility, we consider bulk Mn2Au with the two spin sublattices forming inversion partners, and a 2D square-lattice antiferromagnet with broken structural inversion symmetry modeled by a Rashba spin-orbit coupling. We propose an antiferromagnetic memory device with electrical writing and reading.

  17. Study of spin-polaron formation in 1D systems

    Energy Technology Data Exchange (ETDEWEB)

    Arredondo, Y.; Navarro, O. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, 04510 México D.F. (Mexico); Vallejo, E. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Coahuila, Carretera Torreón-Matamoros Km. 7.5 Ciudad Universitaria, 27276 Torreón, Coahuila (Mexico)

    2014-05-15

    We study numerically the formation of spin-polarons in low-dimensional systems. We consider a ferromagnetic Kondo lattice model with Hund coupling J{sub H} and localized spins interacting antiferromagnetically with coupling constant J. We investigate the ground state phase diagram as a function of the exchange couplings J{sub H} and J and as a function of the band filling, since it has been observed that doping either on the ferromagnetic or antiferromagnetic regime lead to formation of magnetic domains [1]. We explore the quasi-particle formation and phase separation using the density-matrix renormalization group method, which is a highly efficient method to investigate quasi-one-dimensional strongly correlated systems.

  18. Brownian motion and entropic torque driven motion of domain walls in antiferromagnets

    Science.gov (United States)

    Yan, Zhengren; Chen, Zhiyuan; Qin, Minghui; Lu, Xubing; Gao, Xingsen; Liu, Junming

    2018-02-01

    We study the spin dynamics in antiferromagnetic nanowire under an applied temperature gradient using micromagnetic simulations on a classical spin model with a uniaxial anisotropy. The entropic torque driven domain-wall motion and the Brownian motion are discussed in detail, and their competition determines the antiferromagnetic wall motion towards the hotter or colder region. Furthermore, the spin dynamics in an antiferromagnet can be well tuned by the anisotropy and the temperature gradient. Thus, this paper not only strengthens the main conclusions obtained in earlier works [Kim et al., Phys. Rev. B 92, 020402(R) (2015), 10.1103/PhysRevB.92.020402; Selzer et al., Phys. Rev. Lett. 117, 107201 (2016), 10.1103/PhysRevLett.117.107201], but more importantly gives the concrete conditions under which these conclusions apply, respectively. Our results may provide useful information on the antiferromagnetic spintronics for future experiments and storage device design.

  19. Long Range Order and Spin-Fluctuations in Strongly Correlated Electron System with Valence Instability

    Science.gov (United States)

    Alekseev, P. A.; Menushenkov, A. P.; Mignot, J.-M.; Nemkovski, K. S.; Yaroslavtsev, A. A.; Kozlenko, D. P.

    Rare-earth based strongly correlated electron systems (SCES) exhibit a large variety of different ground states, ranging from the simple paramagnetism of crystal-field-split f-electron multiplets to highly unconventional Kondo-insulator states with a combination of charge gap, spin gap and valence instability, in which long-range magnetic order can eventually arise from an initially singlet state. The physical background for these properties of the electron subsystem may be clarified by performing detailed neutron scattering experiments, namely magnetic neutron scattering spectroscopy and diffraction. This report reviews the results of the previous and new experimental studies on a number of rare-earth intermetallic compounds, which shed light on peculiar features of those unusual ground states.

  20. Correlation mediated superconductivity in a Spin Peierls Phase of the Hubbard Model

    International Nuclear Information System (INIS)

    Long, M.W.

    1987-08-01

    The author explores the consequences of a mapping of the Hubbard Hamiltonian with a view to finding possible superconducting phases. The transformation pairs up all the sites and is therefore a much more natural starting point for describing a 'Spin Peierls' transition, generating enhanced singlet correlations for this pairing, than it is for describing the 'Resonating Valence Bond' state. It is shown that in the less than half filling case, an effective non-linear hopping Hamiltonian is quite useful in describing half of the electrons. This effective Hamiltonian can show a form of superconducting instability when nearest neighbour hopping is introduced to stabilise it. This superconducting phase seems to be a very unlikely possibility for the standard Hubbard model. (author)

  1. A T-shaped double quantum dot system as a Fano interferometer: Interplay of coherence and correlation upon spin currents

    Science.gov (United States)

    Fernandes, I. L.; Cabrera, G. G.

    2018-05-01

    Based on Keldysh non-equilibrium Green function method, we have investigated spin current production in a hybrid T-shaped device, consisting of a central quantum dot connected to the leads and a side dot which only couples to the central dot. The topology of this structure allows for quantum interference of the different paths that go across the device, yielding Fano resonances in the spin dependent transport properties. Correlation effects are taken into account at the central dot and handled within a mean field approximation. Its interplay with the Fano effect is analyzed in the strong coupling regime. Non-vanishing spin currents are only obtained when the leads are ferromagnetic, the current being strongly dependent on the relative orientation of the lead polarizations. We calculate the conductance (spin and charge) by numerically differentiating the current, and a rich structure is obtained as a manifestation of quantum coherence and correlation effects. Increase of the Coulomb interaction produces localization of states at the side dot, largely suppressing Fano resonances. The interaction is also responsible for the negative values of the spin conductance in some regions of the voltage near resonances, effect which is the spin analog of the Esaki tunnel diode. We also analyze control of the currents via gate voltages applied to the dots, possibility which is interesting for practical operations.

  2. An effective correlated mean-field theory applied in the spin-1/2 Ising ferromagnetic model

    Energy Technology Data Exchange (ETDEWEB)

    Roberto Viana, J.; Salmon, Octávio R. [Universidade Federal do Amazonas – UFAM, Manaus 69077-000, AM (Brazil); Ricardo de Sousa, J. [Universidade Federal do Amazonas – UFAM, Manaus 69077-000, AM (Brazil); National Institute of Science and Technology for Complex Systems, Universidade Federal do Amazonas, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Neto, Minos A.; Padilha, Igor T. [Universidade Federal do Amazonas – UFAM, Manaus 69077-000, AM (Brazil)

    2014-11-15

    We developed a new treatment for mean-field theory applied in spins systems, denominated effective correlated mean-field (ECMF). We apply this theory to study the spin-1/2 Ising ferromagnetic model with nearest-neighbor interactions on a square lattice. We use clusters of finite sizes and study the criticality of the ferromagnetic system, where we obtain a convergence of critical temperature for the value k{sub B}T{sub c}/J≃2.27905±0.00141. Also the behavior of magnetic and thermodynamic properties, using the condition of minimum energy of the physical system is obtained. - Highlights: • We developed spin models to study real magnetic systems. • We study the thermodynamic and magnetic properties of the ferromagnetism. • We enhanced a mean-field theory applied in spins models.

  3. Quantum correlations at infinite temperature: The dynamical Nagaoka effect

    Science.gov (United States)

    Kanász-Nagy, Márton; Lovas, Izabella; Grusdt, Fabian; Greif, Daniel; Greiner, Markus; Demler, Eugene A.

    2017-07-01

    Do quantum correlations play a role in high-temperature dynamics of many-body systems? A common expectation is that thermal fluctuations lead to fast decoherence and make dynamics classical. In this paper we provide a striking example that a single particle created in a featureless, infinite temperature spin bath not only exhibits nonclassical dynamics but it also induces strong long-lived correlations between the surrounding spins. We study the nonequilibrium dynamics of a hole created in a Mott insulator in the atomic limit, which corresponds to a degenerate spin system. In the absence of interactions, the spin correlations arise purely from quantum interference. Furthermore, these correlations are both antiferromagnetic and ferromagnetic, in striking contrast to the equilibrium Nagaoka effect. These results are relevant for a number of condensed matter spin systems and should be observable using state of the art bosonic or fermionic quantum gas microscopes.

  4. Weyl magnons in noncoplanar stacked kagome antiferromagnets

    Science.gov (United States)

    Owerre, S. A.

    2018-03-01

    Weyl nodes have been experimentally realized in photonic, electronic, and phononic crystals. However, magnonic Weyl nodes are yet to be seen experimentally. In this paper, we propose Weyl magnon nodes in noncoplanar stacked frustrated kagome antiferromagnets, naturally available in various real materials. Most crucially, the Weyl nodes in the current system occur at the lowest excitation and possess a topological thermal Hall effect, therefore they are experimentally accessible at low temperatures due to the population effect of bosonic quasiparticles. In stark contrast to other magnetic systems, the current Weyl nodes do not rely on time-reversal symmetry breaking by the magnetic order. Rather, they result from explicit macroscopically broken time reversal symmetry by the scalar spin chirality of noncoplanar spin textures and can be generalized to chiral spin liquid states. Moreover, the scalar spin chirality gives a real space Berry curvature which is not available in previously studied magnetic Weyl systems. We show the existence of magnon arc surface states connecting projected Weyl magnon nodes on the surface Brillouin zone. We also uncover the first realization of triply-degenerate nodal magnon point in the noncollinear regime with zero scalar spin chirality.

  5. Development of antiferromagnetic Heusler alloys for the replacement of iridium as a critically raw material

    Science.gov (United States)

    Hirohata, Atsufumi; Huminiuc, Teodor; Sinclair, John; Wu, Haokaifeng; Samiepour, Marjan; Vallejo-Fernandez, Gonzalo; O'Grady, Kevin; Balluf, Jan; Meinert, Markus; Reiss, Günter; Simon, Eszter; Khmelevskyi, Sergii; Szunyogh, Laszlo; Yanes Díaz, Rocio; Nowak, Ulrich; Tsuchiya, Tomoki; Sugiyama, Tomoko; Kubota, Takahide; Takanashi, Koki; Inami, Nobuhito; Ono, Kanta

    2017-11-01

    As a platinum group metal, iridium (Ir) is the scarcest element on the earth but it has been widely used as an antiferromagnetic layer in magnetic recording, crucibles and spark plugs due to its high melting point. In magnetic recording, antiferromagnetic layers have been used to pin its neighbouring ferromagnetic layer in a spin-valve read head in a hard disk drive for example. Recently, antiferromagnetic layers have also been found to induce a spin-polarised electrical current. In these devices, the most commonly used antiferromagnet is an Ir-Mn alloy because of its corrosion resistance and the reliable magnetic pinning of adjacent ferromagnetic layers. It is therefore crucial to explore new antiferromagnetic materials without critical raw materials. In this review, recent research on new antiferromagnetic Heusler alloys and their exchange interactions along the plane normal is discussed. These new antiferromagnets are characterised by very sensitive magnetic and electrical measurement techniques recently developed to determine their characteristic temperatures together with atomic structural analysis. Mn-based alloys and compounds are found to be most promising based on their robustness against atomic disordering and large pinning strength up to 1.4 kOe, which is comparable with that for Ir-Mn. The search for new antiferromagnetic films and their characterisation are useful for further miniaturisation and development of spintronic devices in a sustainable manner.

  6. Correlated spins of complementary fragment pairs in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Smith, A. G.; Simpson, G. S.; Billowes, J.; Dagnall, P. J.; Durell, J. L.; Freeman, S. J.; Leddy, M.; Phillips, W. R.; Roach, A. A.; Smith, J. F.

    1999-01-01

    A study of the γ-ray decay of low-lying excited states in fragments produced in the spontaneous fission of 252 Cf has revealed a significant correlation between the angles of emission of the 2 1 + →0 1 + transitions of complementary fragment pairs. Calculations of the amount of dealignment that is needed to reproduce the measured a 2 values, and a comparison with the results of previous fragment-γ angular distribution measurements, suggests that at scission there may be significant population of m≠0 substates associated with the projection of the fragment spin vector on the fission axis. Fragments from the spontaneous fission of 248 Cm emit 2 1 + →0 1 + γ rays that show markedly reduced interfragment correlations, suggesting that either a larger role is played by the relative angular momentum of the fragments, or that the dealignment introduced by the neutron emission and statistical γ decay to the 2 1 + state is larger in 248 Cm than 252 Cf fission. (c) 1999 The American Physical Society

  7. New correlation potential for the local-spin-density functional formalism. II

    International Nuclear Information System (INIS)

    Kolar, M.; Farkas, L.

    1982-01-01

    Using the new parameterization for the correlation potential which seems to be the best that is at present available within the local-spin-density (LSD) functional formalism, the Fermi contact term in light atoms (up to Ni) is calculated. Although the overall improvement of the previous LSD results is obtained, discrepancy between theory and experiment remains rather large. It seems that the local approximation for exchange and correlation fails to predict such quantities as magnetic-moment density near the nucleus. It is also shown that the self-interaction correction does not remedy this failure. Further, the effect of the nonzero nuclear radius is investigated and found to be most important in the lightest atoms (e.g. a factor of 0.664 appears in the case of Li). This fact was omitted in all previous calculations and throws doubt on the reported excellent agreement of the results of many-body perturbation theory with experiment. It was also verified that the contact approximation of the Fermi contact term is really good enough. (author)

  8. Magnetic phase diagrams of classical triangular and kagome antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Gvozdikova, M V [Department of Physics, Kharkov National University, 61077 Kharkov (Ukraine); Melchy, P-E; Zhitomirsky, M E, E-mail: mike.zhitomirsky@cea.fr [Service de Physique Statistique, Magnetisme et Supraconductivite, UMR-E9001 CEA-INAC/UJF, 17 rue des Martyrs, 38054 Grenoble (France)

    2011-04-27

    We investigate the effect of geometrical frustration on the H-T phase diagrams of the classical Heisenberg antiferromagnets on triangular and kagome lattices. The phase diagrams for the two models are obtained from large-scale Monte Carlo simulations. For the kagome antiferromagnet, thermal fluctuations are unable to lift degeneracy completely and stabilize translationally disordered multipolar phases. We find a substantial difference in the temperature scales of the order by disorder effect related to different degeneracy of the low- and the high-field classical ground states in the kagome antiferromagnet. In the low-field regime, the Kosterlitz-Thouless transition into a spin-nematic phase is produced by unbinding of half-quantum vortices.

  9. Effective Hamiltonian and low-lying eigenenergy clustering patterns of four-sublattice antiferromagnets

    DEFF Research Database (Denmark)

    Zhang, N.G.; Henley, C.L.; Rischel, C.

    2002-01-01

    We study the low-lying eigenenergy clustering patterns of quantum antiferromagnets with p sublattices (in particular p = 4). We treat each sublattice as a large spin, and using second-order degenerate perturbation theory, we derive the effective (biquadratic) Hamiltonian coupling the p large spins....... In order to compare with exact diagonalizations, the Hamiltonian is explicitly written for a finite-size lattice, and it contains information on energies of excited states as well as the ground state. The result is applied to the face-centered-cubic Type-I antiferromagnet of spin 1/2, including second...

  10. Spin Correlation in $t \\bar{t}$ Production from $p\\bar{p}$ Collisions at $\\sqrt{s}$ = 1.8-TeV

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Suyong [Seoul Natl. U.

    1999-01-01

    The Standard Model predicts that the lifetime of the top quark is shorter than the typical time scale at which hadronization process occurs, and the spin information at its production is preserved. Spin correlation of the $t\\overline{t}$ system from $p\\overline{p}$ collisions at the Tevatron is analyzed using 6 events in the dilepton channels collected using the D0 detector. Spin correlation factor of $\\kappa$ > -0:25 at 68% CL is obtained from the data.

  11. Spin dynamics simulations of topological magnon insulators: From transverse current correlation functions to the family of magnon Hall effects

    Science.gov (United States)

    Mook, Alexander; Henk, Jürgen; Mertig, Ingrid

    2016-11-01

    We demonstrate theoretically that atomistic spin dynamics simulations of topological magnon insulators (TMIs) provide access to the magnon-mediated transport of both spin and heat. The TMIs, modeled by kagome ferromagnets with Dzyaloshinskii-Moriya interaction, exhibit nonzero transverse-current correlation functions from which conductivities are derived for the entire family of magnon Hall effects. Both longitudinal and transverse conductivities are studied in dependence on temperature and on an external magnetic field. A comparison between theoretical and experimental results for Cu(1,3-benzenedicarboxylate), a recently discovered TMI, is drawn.

  12. Superconducting pairing of spin polarons in the t - J model

    International Nuclear Information System (INIS)

    Plakida, N.M.; Horsch, P.; Liechtenstein, A.; Oudovenko, V.S.

    1995-07-01

    A spin polaron model derived from the t - J model on a two-sublattice antiferromagnet is considered. The self-consistent Born approximation for the matrix Green functions for doped holes (spin polarons) and magnons is used to study temperature and doping dependence of the quasi-particle hole spectrum and superconducting pairing of two holes on different sublattices. A numerical solution of the self-consistent system of equations by the fast Fourier transformation method shows a strong renormalization of the quasi-particle hole spectrum due to spin fluctuations, and a singlet superconducting pairing of d-wave symmetry with maximal T c ∼ 0.01t around the hole concentration 0.25. We argue that the superconducting pairing of spin polarons for the model with strong electron correlations represents the mechanism of high-temperature superconductivity. (author). 26 refs, 10 figs

  13. Antiferromagnetic exchange mechanism of superconductivity in cuprates

    CERN Document Server

    Plakida, N M

    2001-01-01

    One examines theory of superconducting coupling resulted from antiferromagnetic exchange in terms of which one explains strong dependence of T sub c superconducting transition temperature on alpha lattice constant. Calculations are based on the Hubbard p-d two-region model within strong correlation limit. DELTA pd excitation high energy at antiferromagnetic exchange of two particles from different Hubbard subregions results in suppression o delay effects and in coupling of all particles in conductivity subregion with Fermi energy E sub F >= DELTA pd : T sub c approx = E sub F exp(-1/lambda), where lambda propor to J. T sub c (alpha) and isotopic effect are explained by J exchange interaction dependence on alpha and on zero oscillations of oxygen ions

  14. Ab initio dynamical exchange interactions in frustrated antiferromagnets

    Science.gov (United States)

    Simoni, Jacopo; Stamenova, Maria; Sanvito, Stefano

    2017-08-01

    The ultrafast response to an optical pulse excitation of the spin-spin exchange interaction in transition metal antiferromagnets is studied within the framework of the time-dependent spin-density functional theory. We propose a formulation for the full dynamical exchange interaction, which is nonlocal in space, and it is derived starting from ab initio arguments. Then, we investigate the effect of the laser pulse on the onset of the dynamical process. It is found that we can distinguish two types of excitations, both activated immediately after the action of the laser pulse. While the first one can be associated to a Stoner-like excitation and involves the transfer of spin from one site to another, the second one is related to the ultrafast modification of a Heisenberg-like exchange interaction and can trigger the formation of spin waves in the first few hundred femtoseconds of the time evolution.

  15. Spin-echo based diagonal peak suppression in solid-state MAS NMR homonuclear chemical shift correlation spectra

    Science.gov (United States)

    Wang, Kaiyu; Zhang, Zhiyong; Ding, Xiaoyan; Tian, Fang; Huang, Yuqing; Chen, Zhong; Fu, Riqiang

    2018-02-01

    The feasibility of using the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed in such a way that in the indirect dimension only the spin diffused signals are evolved, while all signals not involved in polarization transfer are refocused for cancellation. A data processing procedure is further introduced to reconstruct this acquired spectrum into a conventional two-dimensional homonuclear chemical shift correlation spectrum. A uniformly 13C, 15N labeled Fmoc-valine sample and the transmembrane domain of a human protein, LR11 (sorLA), in native Escherichia coli membranes have been used to illustrate the capability of the proposed method in comparison with standard 13C-13C chemical shift correlation experiments.

  16. Dynamical pairwise entanglement and two-point correlations in the three-ligand spin-star structure

    Science.gov (United States)

    Motamedifar, M.

    2017-10-01

    We consider the three-ligand spin-star structure through homogeneous Heisenberg interactions (XXX-3LSSS) in the framework of dynamical pairwise entanglement. It is shown that the time evolution of the central qubit ;one-particle; state (COPS) brings about the generation of quantum W states at periodical time instants. On the contrary, W states cannot be generated from the time evolution of a ligand ;one-particle; state (LOPS). We also investigate the dynamical behavior of two-point quantum correlations as well as the expectation values of the different spin-components for each element in the XXX-3LSSS. It is found that when a W state is generated, the same value of the concurrence between any two arbitrary qubits arises from the xx and yy two-point quantum correlations. On the opposite, zz quantum correlation between any two qubits vanishes at these time instants.

  17. Spin control of 12B and 12N and the axial charge from their β-ray spin-alignment correlations

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Minamisono, K.; Ikeda, T.; Muramoto, Y.; Fukuda, M.; Matsuta, K.; Nojiri, Y.; Minamisono, T.

    1999-01-01

    The spin manipulation technique by use of the β-NMR is further refined, based on the recent thorough studies of hyperfine interactions of 12 B and 12 N in Mg. By using this technique, the alignment correlation terms in the β-ray angular distribution of the A = 12 system are precisely measured, so that the axial charge is singled out to be y = 4.66 ± 0.06 (stat.) ± 0.13 (syst.) which shows clear mesonic enhancement over the impulse value

  18. Chiral Spin-Density Wave, Spin-Charge-Chern Liquid, and d+id Superconductivity in 1/4-Doped Correlated Electronic Systems on the Honeycomb Lattice

    Directory of Open Access Journals (Sweden)

    Shenghan Jiang

    2014-09-01

    Full Text Available Recently, two interesting candidate quantum phases—the chiral spin-density wave state featuring anomalous quantum Hall effect and the d+id superconductor—were proposed for the Hubbard model on the honeycomb lattice at 1/4 doping. Using a combination of exact diagonalization, density matrix renormalization group, the variational Monte Carlo method, and quantum field theories, we study the quantum phase diagrams of both the Hubbard model and the t-J model on the honeycomb lattice at 1/4 doping. The main advantage of our approach is the use of symmetry quantum numbers of ground-state wave functions on finite-size systems (up to 32 sites to sharply distinguish different quantum phases. Our results show that for 1≲U/t<40 in the Hubbard model and for 0.1spin-density wave state or a spin-charge-Chern liquid, but not a d+id superconductor. However, in the t-J model, upon increasing J, the system goes through a first-order phase transition at J/t=0.80(2 into the d+id superconductor. Here, the spin-charge-Chern liquid state is a new type of topologically ordered quantum phase with Abelian anyons and fractionalized excitations. Experimental signatures of these quantum phases, such as tunneling conductance, are calculated. These results are discussed in the context of 1/4-doped graphene systems and other correlated electronic materials on the honeycomb lattice.

  19. Manifestations of classical physics in the quantum evolution of correlated spin states in pulsed NMR experiments.

    Science.gov (United States)

    Ligare, Martin

    2016-05-01

    Multiple-pulse NMR experiments are a powerful tool for the investigation of molecules with coupled nuclear spins. The product operator formalism provides a way to understand the quantum evolution of an ensemble of weakly coupled spins in such experiments using some of the more intuitive concepts of classical physics and semi-classical vector representations. In this paper I present a new way in which to interpret the quantum evolution of an ensemble of spins. I recast the quantum problem in terms of mixtures of pure states of two spins whose expectation values evolve identically to those of classical moments. Pictorial representations of these classically evolving states provide a way to calculate the time evolution of ensembles of weakly coupled spins without the full machinery of quantum mechanics, offering insight to anyone who understands precession of magnetic moments in magnetic fields.

  20. Spin-glass transition in disordered terbium

    International Nuclear Information System (INIS)

    Hauser, J.J.

    1985-01-01

    While crystalline Tb is a helix antiferromagnet with a Neel temperature of 229 K which becomes ferromagnetic at 222 K, disordered Tb exhibits a spin-glass transition. The spin-glass freezing temperature ranges from 183 to 53 K, the lowest temperatures corresponding to the greatest degree of atomic disorder. These experiments constitute the first evidence for an elemental spin-glass. (author)

  1. Magnetic properties of a diluted transverse spin-1 Ising nanocube with a longitudinal crystal-field

    Science.gov (United States)

    El Hamri, M.; Bouhou, S.; Essaoudi, I.; Ainane, A.; Ahuja, R.

    2016-12-01

    In the present work, the effective field theory with correlations based on the probability distribution technique has been used to investigate the effect of the surface shell longitudinal cristal field on the magnetic properties of a diluted antiferromagnetic spin-1 Ising nanocube particle. This effect has also been studied on the hysteresis loops of the system. It is found that this parameter has a strong effect on the magnetization profiles, compensation temperature, coercive field and remanent magnetization.

  2. The epitaxial Bain path of antiferromagnetic tetragonal Mn

    Science.gov (United States)

    Qiu, S. L.; Marcus, P. M.; Ma, Hong

    2000-03-01

    The epitaxial Bain path (EBP) of antiferromagnetic (AF) tetragonal Mn has been found by first-principles total-energy calculations using the full-potential linearized-augmented-plane-wave (FLAPW) method with two different potentials: (1) the local-spin-density-approximation without relativistic corrections (LSDA-NREL) and (2) the Perdew-Burke-Ernzerhof exchange-correlation potential in a generalized-gradient-approximation with relativistic corrections (GGA-REL). The EBP curve of AF Mn from the LSDA-NREL calculations shows a metastable tetragonal state at c/a = 0.68 (fct notation) and a stable tetragonal state at c/a = 0.99. The EBP curve from the GGA-REL calculations shows that these two states are at c/a = 0.60 and 0.96 respectively. Alloy measurements[1] find the stable tetragonal state at c/a = 0.95. The bcc state at c/a = 0.707 is inherently unstable from both LSDA and GGA calculations. The volume vs c/a curve shows that when grown epitaxially[2] on V and Pd, the AF Mn films are strained δ-Mn and γ-Mn respectively. [1] Y. Endoh and Y. Ishikawa, J. Phys. Soc. Jpn., 30 1614 (1971). [2] Y. Tian, F. Jona, and P. M. Marcus, Phys. Rev. B59, 12647 (1999).

  3. The Landau-Lifshitz equation describes the Ising spin correlation function in the free-fermion model

    CERN Document Server

    Rutkevich, S B

    1998-01-01

    We consider time and space dependence of the Ising spin correlation function in a continuous one-dimensional free-fermion model. By the Ising spin we imply the 'sign' variable, which takes alternating +-1 values in adjacent domains bounded by domain walls (fermionic world paths). The two-point correlation function is expressed in terms of the solution of the Cauchy problem for a nonlinear partial differential equation, which is proved to be equivalent to the exactly solvable Landau-Lifshitz equation. A new zero-curvature representation for this equation is presented. In turn, the initial condition for the Cauchy problem is given by the solution of a nonlinear ordinary differential equation, which has also been derived. In the Ising limit the above-mentioned partial and ordinary differential equations reduce to the sine-Gordon and Painleve III equations, respectively. (author)

  4. Vector correlation analysis for inelastic and reactive collisions between partners possessing spin and orbital angular momentum.

    Science.gov (United States)

    Balint-Kurti, Gabriel G; Vasyutinskii, Oleg S

    2009-12-31

    A general reactive collision of the type A + B --> C + D is considered where both the collision partners (A and B) or the products (C and D) may possess internal, i.e., spin, orbital or rotational, angular momenta. Compact expressions are derived using a rigorous quantum mechanical analysis for the angular momentum anisotropy of either of the products (C or D) arising from an initially polarized distribution of the reactant angular momentum. The angular momentum distribution of the product is expressed in terms of canonical spherical tensors multiplied by anisotropy-transforming coefficients c(K(i)q(k))(K)(K(r),L). These coefficients act as transformation coefficients between the angular momentum anisotropy of the reactants and that of the product. They are independent of scattering angle but depend on the details of the scattering dynamics. The relationship between the coefficients c(K(i)q(k))(K)(K(r),L) and the body-fixed scattering S matrix is given and the methodology for the quantum mechanical calculation of the anisotropy-transforming coefficients is clearly laid out. The anisotropy-transforming coefficients are amenable to direct experimental measurement in a similar manner to vector correlation and alignment parameters in photodissociation processes. A key aspect of the theory is the use of projections of both reactant and product angular momenta onto the product recoil vector direction. An important new conservation rule is revealed through the analysis, namely that if the state multipole for reactant angular momentum distribution has a projection q(k) onto the product recoil vector the state multipoles for the product angular momentum distribution all have this same projection. Expressions are also presented for the distribution of the product angular momentum when its components are evaluated relative to the space-fixed Z-axis. Notes with detailed derivations of all the formulas are available as Supporting Information.

  5. Spin-polarized ballistic conduction through correlated Au-NiMnSb-Au heterostructures

    KAUST Repository

    Morari, C.

    2017-11-20

    We examine the ballistic conduction through Au-NiMnSb-Au heterostructures consisting of up to four units of the half-metallic NiMnSb in the scattering region, using density functional theory (DFT) methods. For a single NiMnSb unit the transmission function displays a spin polarization of around 50% in a window of 1eV centered around the Fermi level. By increasing the number of layers, an almost complete spin polarization of the transmission is obtained in this energy range. Supplementing the DFT calculations with local electronic interactions, of Hubbard-type on the Mn sites, leads to a hybridization between the interface and many-body states. The significant reduction of the spin polarization seen in the density of states is not apparent in the spin polarization of the conduction electron transmission, which suggests that the hybridized interface and many-body induced states are localized.

  6. Indirectly detected chemical shift correlation NMR spectroscopy in solids under fast magic angle spinning

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Kanmi [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The development of fast magic angle spinning (MAS) opened up an opportunity for the indirect detection of insensitive low-γ nuclei (e.g., 13C and 15N) via the sensitive high-{gamma} nuclei (e.g., 1H and 19F) in solid-state NMR, with advanced sensitivity and resolution. In this thesis, new methodology utilizing fast MAS is presented, including through-bond indirectly detected heteronuclear correlation (HETCOR) spectroscopy, which is assisted by multiple RF pulse sequences for 1H-1H homonuclear decoupling. Also presented is a simple new strategy for optimization of 1H-1H homonuclear decoupling. As applications, various classes of materials, such as catalytic nanoscale materials, biomolecules, and organic complexes, are studied by combining indirect detection and other one-dimensional (1D) and two-dimensional (2D) NMR techniques. Indirectly detected through-bond HETCOR spectroscopy utilizing refocused INEPT (INEPTR) mixing was developed under fast MAS (Chapter 2). The time performance of this approach in 1H detected 2D 1H{l_brace}13C{r_brace} spectra was significantly improved, by a factor of almost 10, compared to the traditional 13C detected experiments, as demonstrated by measuring naturally abundant organic-inorganic mesoporous hybrid materials. The through-bond scheme was demonstrated as a new analytical tool, which provides complementary structural information in solid-state systems in addition to through-space correlation. To further benefit the sensitivity of the INEPT transfer in rigid solids, the combined rotation and multiple-pulse spectroscopy (CRAMPS) was implemented for homonuclear 1H decoupling under fast MAS (Chapter 3). Several decoupling schemes (PMLG5m$\\bar{x}$, PMLG5mm$\\bar{x}$x and SAM3) were analyzed to maximize the performance of through-bond transfer based

  7. Quantum phase transitions in effective spin-ladder models for graphene zigzag nanoribbons

    Science.gov (United States)

    Koop, Cornelie; Wessel, Stefan

    2017-10-01

    We examine the magnetic correlations in quantum spin models that were derived recently as effective low-energy theories for electronic correlation effects on the edge states of graphene nanoribbons. For this purpose, we employ quantum Monte Carlo simulations to access the large-distance properties, accounting for quantum fluctuations beyond mean-field-theory approaches to edge magnetism. For certain chiral nanoribbons, antiferromagnetic interedge couplings were previously found to induce a gapped quantum disordered ground state of the effective spin model. We find that the extended nature of the intraedge couplings in the effective spin model for zigzag nanoribbons leads to a quantum phase transition at a large, finite value of the interedge coupling. This quantum critical point separates the quantum disordered region from a gapless phase of stable edge magnetism at weak intraedge coupling, which includes the ground states of spin-ladder models for wide zigzag nanoribbons. To study the quantum critical behavior, the effective spin model can be related to a model of two antiferromagnetically coupled Haldane-Shastry spin-half chains with long-ranged ferromagnetic intrachain couplings. The results for the critical exponents are compared also to several recent renormalization-group calculations for related long-ranged interacting quantum systems.

  8. Correlation between magnetic spin structure and the three-dimensional geometry in chemically synthesized nanoscale magnetite rings

    DEFF Research Database (Denmark)

    Eltschka, M.; Klaui, M.; Rudiger, U

    2008-01-01

    The correlation between magnetic spin structure and geometry in nanoscale chemically synthesized Fe3O4 rings has been investigated by transmission electron microscopy. We find primarily the flux closure vortex states but in rings with thickness variations, an effective stray field occurs. Using t....... The interaction between exchange coupled rings leads to antiparallel vortex states and extended onion states. (c) 2008 American Institute of Physics....

  9. Dynamic rotor mode in antiferromagnetic nanoparticles

    DEFF Research Database (Denmark)

    Lefmann, Kim; Jacobsen, H.; Garde, J.

    2015-01-01

    measured neutron data and reveal that thermally activated spin canting gives rise to an unusual type of coherent magnetic precession mode. This "rotor" mode can be seen as a high-temperature version of superparamagnetism and is driven by exchange interactions between the two magnetic sublattices......We present experimental, numerical, and theoretical evidence for an unusual mode of antiferromagnetic dynamics in nanoparticles. Elastic neutron scattering experiments on 8-nm particles of hematite display a loss of diffraction intensity with temperature, the intensity vanishing around 150 K....... The frequency of the rotor mode behaves in fair agreement with a simple analytical model, based on a high-temperature approximation of the generally accepted Hamiltonian of the system. The extracted model parameters, such as the magnetic interaction and the axial anisotropy, are in excellent agreement...

  10. Correlation Effects and Hidden Spin-Orbit Entangled Electronic Order in Parent and Electron-Doped Iridates Sr_{2}IrO_{4}

    Directory of Open Access Journals (Sweden)

    Sen Zhou

    2017-10-01

    Full Text Available Analogs of the high-T_{c} cuprates have been long sought after in transition metal oxides. Because of the strong spin-orbit coupling, the 5d perovskite iridates Sr_{2}IrO_{4} exhibit a low-energy electronic structure remarkably similar to the cuprates. Whether a superconducting state exists as in the cuprates requires understanding the correlated spin-orbit entangled electronic states. Recent experiments discovered hidden order in the parent and electron-doped iridates, some with striking analogies to the cuprates, including Fermi surface pockets, Fermi arcs, and pseudogap. Here, we study the correlation and disorder effects in a five-orbital model derived from the band theory. We find that the experimental observations are consistent with a d-wave spin-orbit density wave order that breaks the symmetry of a joint twofold spin-orbital rotation followed by a lattice translation. There is a Berry phase and a plaquette spin flux due to spin procession as electrons hop between Ir atoms, akin to the intersite spin-orbit coupling in quantum spin Hall insulators. The associated staggered circulating J_{eff}=1/2 spin current can be probed by advanced techniques of spin-current detection in spintronics. This electronic order can emerge spontaneously from the intersite Coulomb interactions between the spatially extended iridium 5d orbitals, turning the metallic state into an electron-doped quasi-2D Dirac semimetal with important implications on the possible superconducting state suggested by recent experiments.

  11. Neutron-scattering study of static antiferromagnetic correlations in La2-xSrxCu1-yZnyO4

    International Nuclear Information System (INIS)

    Kimura, H.; Hirota, K.; Matsushita, H.; Yamada, K.; Endoh, Y.; Lee, S.; Majkrzak, C.F.; Erwin, R.; Shirane, G.; Greven, M.; Lee, Y.S.; Kastner, M.A.; Birgeneau, R.J.

    1999-01-01

    Neutron-scattering measurements have been performed to search for possible elastic incommensurate magnetic peaks in superconducting La 2-x Sr x CuO 4 with x=0.10, 0.12, and 0.15. The most dramatic effects are found for x=0.12; in this case, the peak intensity first appears at the onset of superconductivity T c (=31 K). The resolution-limited peak width indicates that the static magnetic correlation length exceeds 200 Angstrom isotropically in the CuO 2 planes. Weak elastic peaks are also observed at low temperatures for x=0.10 while for x=0.15 any incommensurate elastic scattering is below the limit of detectability. Elastic peaks are observed in Zn-substituted nonsuperconducting La 1.88 Sr 0.12 Cu 0.97 Zn 0.03 0 4 . However, in this case, the Zn substitution degrades the magnetic order; the peak appears at lower temperature (17 K) and the correlation length is shorter (80 Angstrom) than that in the Zn-free x=0.12 sample. copyright 1999 The American Physical Society

  12. Orbital-dependent second-order scaled-opposite-spin correlation functionals in the optimized effective potential method

    Energy Technology Data Exchange (ETDEWEB)

    Grabowski, Ireneusz, E-mail: ig@fizyka.umk.pl; Śmiga, Szymon; Buksztel, Adam [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Fabiano, Eduardo [National Nanotechnology Laboratory, Istituto Nanoscienze–CNR, Via per Arnesano, I-73100 Lecce (Italy); Teale, Andrew M. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); Sala, Fabio Della [National Nanotechnology Laboratory, Istituto Nanoscienze–CNR, Via per Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies @UNILE, Istituto Italiano di Tecnologia (IIT), Via Barsanti, 73010 Arnesano (LE) (Italy)

    2014-07-14

    The performance of correlated optimized effective potential (OEP) functionals based on the spin-resolved second-order correlation energy is analysed. The relative importance of singly- and doubly- excited contributions as well as the effect of scaling the same- and opposite- spin components is investigated in detail comparing OEP results with Kohn–Sham (KS) quantities determined via an inversion procedure using accurate ab initio electronic densities. Special attention is dedicated in particular to the recently proposed scaled-opposite–spin OEP functional [I. Grabowski, E. Fabiano, and F. Della Sala, Phys. Rev. B 87, 075103 (2013)] which is the most advantageous from a computational point of view. We find that for high accuracy, a careful, system dependent, selection of the scaling coefficient is required. We analyse several size-extensive approaches for this selection. Finally, we find that a composite approach, named OEP2-SOSh, based on a post-SCF rescaling of the correlation energy can yield high accuracy for many properties, being comparable with the most accurate OEP procedures previously reported in the literature but at substantially reduced computational effort.

  13. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    Science.gov (United States)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E. M.

    1991-10-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$-- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y2).

  14. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    International Nuclear Information System (INIS)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E.M.

    1991-01-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$---- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y 2 )

  15. Temperature dependence of magnetic excitations in the frustrated antiferromagnetic spinel ZnMn2O4

    Science.gov (United States)

    Chang, Hun; Hwang, In-Yong; Chung, Jae-Ho; Stewart, J. Ross; Higemoto, Wataru; Miyake, Yasuhiro

    2018-01-01

    We report the temperature-dependent evolution of spin ordering and excitations of the frustrated tetragonal (c >a ) spinel ZnMn2O4 across the two-dimensional antiferromagnetic transition. Muon spin relaxation indicates full development of ordered magnetic moments immediately below TN=62.7 (2 ) K in spite of the apparent low-dimensional ordering. Using inelastic neutron scattering, we obtained the spin Hamiltonian accounting for the temperature-dependent spin excitations. The damped spin waves at high temperature exhibit a continuous increase in their lifetime on cooling across TN. In contrast, the finite anisotropy gap appears suddenly below TN indicating that single-ion anisotropy stabilizes the antiferromagnetic chains. We also observed the frustrated out-of-plane exchange contributing to the high-energy modes.

  16. Nuclear and magnetic correlations in a topologically frustrated elemental magnet

    International Nuclear Information System (INIS)

    Stewart, J.R.; Andersen, K.H.; Cywinski, R.

    1999-01-01

    β-Mn is an exchange enhanced paramagnetic metal on the verge of antiferromagnetic order. However, strong spin-fluctuations and topological frustration prevent the formation of static long-range order. We investigate the magnetic properties of the β-MnAl series of alloys in which short-range magnetic order is achieved at low temperature. We extract the short-range nuclear and magnetic correlations using a novel reverse Monte-Carlo procedure. (authors)

  17. Noncommutative Wilson lines in higher-spin theory and correlation functions of conserved currents for free conformal fields

    Science.gov (United States)

    Bonezzi, Roberto; Boulanger, Nicolas; De Filippi, David; Sundell, Per

    2017-11-01

    We first prove that, in Vasiliev’s theory, the zero-form charges studied in Sezgin E and Sundell P 2011 (arXiv:1103.2360 [hep-th]) and Colombo N and Sundell P 20 (arXiv:1208.3880 [hep-th]) are twisted open Wilson lines in the noncommutative Z space. This is shown by mapping Vasiliev’s higher-spin model on noncommutative Yang–Mills theory. We then prove that, prior to Bose-symmetrising, the cyclically-symmetric higher-spin invariants given by the leading order of these n-point zero-form charges are equal to corresponding cyclically-invariant building blocks of n-point correlation functions of bilinear operators in free conformal field theories (CFT) in three dimensions. On the higher spin gravity side, our computation reproduces the results of Didenko V and Skvortsov E 2013 J. High Energy Phys. JHEP04(2013)158 using an alternative method amenable to the computation of subleading corrections obtained by perturbation theory in normal order. On the free CFT side, our proof involves the explicit computation of the separate cyclic building blocks of the correlation functions of n conserved currents in arbitrary dimension d>2 using polarization vectors, which is an original result. It is shown to agree, for d=3 , with the results obtained in Gelfond O A and Vasiliev M A 2013 Nucl. Phys. B 876 871–917 in various dimensions and where polarization spinors were used.

  18. Measurement of spin correlation in ttbar production using a matrix element approach

    Czech Academy of Sciences Publication Activity Database

    Abazov, V. M.; Abbott, B.; Acharya, B.S.; Kupčo, Alexander; Lokajíček, Miloš

    2011-01-01

    Roč. 107, č. 3 (2011), "032001-1"-"032001-7" ISSN 0031-9007 R&D Projects: GA MŠk LA08047 Institutional research plan: CEZ:AV0Z10100502 Keywords : D0 * Tevatron * dilepton * anti-p p * spin Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 7.370, year: 2011

  19. Magnetic fluctuations and correlations in MnSi : Evidence for a chiral skyrmion spin liquid phase

    NARCIS (Netherlands)

    Pappas, C.; Lelièvre-Berna, E.; Bentley, P.; Falus, P.; Fouquet, P.; Farago, B.

    2011-01-01

    We present a comprehensive analysis of high-resolution neutron scattering data involving neutron spin echo spectroscopy and spherical polarimetry, which confirm the first-order nature of the helical transition in MnSi. The experiments reveal the existence of a totally chiral dynamic phase in a very

  20. Doping dependence of spin fluctuations and electron correlations in iron pnictides

    Czech Academy of Sciences Publication Activity Database

    Ikeda, H.; Arita, R.; Kuneš, Jan

    2010-01-01

    Roč. 82, č. 2 (2010), 024508/1-024508/6 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : iron pnicitdes * dynamic spin susceptibility * fluctuation- exchange approximation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010 http://prb.aps.org/abstract/PRB/v82/i2/e024508

  1. Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO3

    NARCIS (Netherlands)

    Tomiyasu, K.; Okamoto, Jun; Huang, H. Y.; Chen, Z. Y.; Sinaga, E. P.; Wu, W. B.; Chu, Audrey Y; Singh, A.; Wang, R. P.; De Groot, F. M.F.; Chainani, A.; Ishihara, S; Chen, C. T.; Huang, Di Jing

    2017-01-01

    We carried out temperature-dependent (20-550 K) measurements of resonant inelastic x-ray scattering on LaCoO3 to investigate the evolution of its electronic structure across the spin-state crossover. In combination with charge-transfer multiplet calculations, we accurately quantified the renomalized

  2. Spinon-vison interactions in kagome-lattice spin liquids

    Science.gov (United States)

    Chowdhury, Debanjan; Gopalakrishnan, Sarang; Sachdev, Subir

    2013-03-01

    Recent neutron-scattering measurements on the kagome-lattice antiferromagnet Herbertsmithite suggest that the ground state is well-described by a spin liquid consisting of weakly correlated (i.e., non-dispersing) singlets. We consider how these observations can be accounted for within a Schwinger-boson mean-field theory, by including interactions between spinons (i.e., the spin-1/2 excitations of the Z2 spin liquid) and the topological excitations known as visons. We compute the dynamic structure factor (which is measured in the experiments of Ref.) as a function of a phenomenological spinon-vison coupling constant, and discuss how this coupling constant may be extracted from numerics.

  3. Antiferromagnetism and hot spots in CeIn3

    Science.gov (United States)

    Grigoriev, Pavel; Gor'kov, Lev

    2006-03-01

    Enormous mass enhancement at ``hot spots'' on the Fermi surface (FS) of the antiferromagnetic CeIn3 has been reported at strong magnetic field near its antiferromagnetic quantum critical point [T. Ebihara et al., Phys. Rev. Lett. 93, 246401 (2004)]. The effect was ascribed to anomalous spin fluctuations at these spots owing to peculiar strong many-body interactions. The ``hot spots'' lie at the positions on FS same as in non-magnetic LaIn3 where the narrow necks are protruded, thus, hinting on their possible relation. Assuming that in paramagnetic phase CeIn3 has similar spectrum, we study the influence of the antiferromagnetic ordering (AFM) on the energy spectrum of CeIn3 and show that its FS undergoes a topological change at the onset of AFM. The necks at the ``hot spots'' are truncated by the AFM, thus restoring the almost spherical d-part of the FS of CeIn3. Applied field suppresses the AFM and restores the necks on the FS (so-called 2.5-order phase transition) leading to logarithmic divergence of the dHvA effective mass when the electron trajectory passes near or through the restored necks. This effect fully explains the observed dHvA mass enhancement in the ``hot spots'' in the frameworks of one-particle approximation and leads to the predictions concerning the spin-dependence of the effective electron mass.

  4. Antiferromagnetic Skyrmion: Stability, Creation and Manipulation

    Science.gov (United States)

    Zhang, Xichao; Zhou, Yan; Ezawa, Motohiko

    2016-04-01

    Magnetic skyrmions are particle-like topological excitations in ferromagnets, which have the topo-logical number Q = ± 1, and hence show the skyrmion Hall effect (SkHE) due to the Magnus force effect originating from the topology. Here, we propose the counterpart of the magnetic skyrmion in the antiferromagnetic (AFM) system, that is, the AFM skyrmion, which is topologically protected but without showing the SkHE. Two approaches for creating the AFM skyrmion have been described based on micromagnetic lattice simulations: (i) by injecting a vertical spin-polarized current to a nanodisk with the AFM ground state; (ii) by converting an AFM domain-wall pair in a nanowire junction. It is demonstrated that the AFM skyrmion, driven by the spin-polarized current, can move straightly over long distance, benefiting from the absence of the SkHE. Our results will open a new strategy on designing the novel spintronic devices based on AFM materials.

  5. Spin correlations and magnetic order in Co-Ga alloys: A comprehensive study

    Energy Technology Data Exchange (ETDEWEB)

    Yasin, Sk Mohammad [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Saha, Ritwik [Department of Condensed Matter Physics and Materials Science, TIFR, Colaba, Mumbai 400 005 (India); Srinivas, V., E-mail: veeturi@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Kasiviswanathan, S. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Nigam, A.K. [Department of Condensed Matter Physics and Materials Science, TIFR, Colaba, Mumbai 400 005 (India)

    2015-11-15

    Low temperature magnetic properties of binary Co{sub x}Ga{sub 100−x} alloy with Co concentration in the range 54 ≤ x ≤ 61.5 at% have been investigated. From the temperature and magnetic field dependent magnetization measurements magnetic phase diagram has been identified. Cluster spin glass like features are noticed in x = 54, 55 compositions, while the compositions x > 57 exhibit double magnetic transition i.e., at higher temperatures paramagnetic (PM) – ferromagnetic (FM) and at lower temperatures FM-SG like transition. The critical concentration is identified to be near x = 57 composition where discernible spontaneous magnetization emerges and the long range ferromagnetic order develops above this composition in addition to the spin glass transition (or mixed magnetic phase). Analysis of temperature dependence magnetization data in the different temperature ranges for the compositions x = 60 and 61.5 indicate that the mean field models are not suitable to understand the phase transition. Magnetic isotherms in the critical region were analyzed using non-mean-field approach and the critical exponents (γ = 1.31 and β = 0.337) found to be close to 3D Heisenberg model suggesting the importance of short range magnetic order. The data satisfies magnetic equation of state characteristic of a second order phase transition. The results obtained from the present study corroborate well with the phenomenological interacting spin cluster model. - Graphical abstract: Low temperature magnetic properties of binary Co{sub x}Ga{sub 1−x} alloy with Co concentration in the range 54 ≤ x ≤ 61.5 at% have been investigated. From the temperature and magnetic field dependent magnetization measurements magnetic phase diagram has been identified. Cluster spin glass (SG) like features are noticed in x = 54, 55.5 compositions, while the compositions x > 57 exhibit double magnetic transition i.e., at higher temperatures paramagnetic (PM) – ferromagnetic (FM) and at lower

  6. The thermodynamic spin magnetization of strongly correlated 2d electrons in a silicon inversion layer

    OpenAIRE

    Prus, O.; Yaish, Y.; Reznikov, M.; Sivan, U.; Pudalov, V.

    2002-01-01

    A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the suscep...

  7. GGA+U calculations of correlated spin excitations in LaCoO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Knížek, Karel; Jirák, Zdeněk; Hejtmánek, Jiří; Novák, Pavel; Ku, W.

    2009-01-01

    Roč. 79, č. 1 (2009), 014430/1-014430/8 ISSN 1098-0121 R&D Projects: GA ČR GA202/06/0051; GA AV ČR IAA100100611 Institutional research plan: CEZ:AV0Z10100521 Keywords : ground states * lanthanum compounds * magnetic structure * spin systems Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  8. Soft modes in the easy plane pyrochlore antiferromagnet

    International Nuclear Information System (INIS)

    Champion, J D M; Holdsworth, P C W

    2004-01-01

    Thermal fluctuations lift the high ground state degeneracy of the classical nearest neighbour pyrochlore antiferromagnet, with easy plane anisotropy, giving a first-order phase transition to a long range ordered state. We show, from spin wave analysis and numerical simulation, that even below this transition a continuous manifold of states, of dimension N 2/3 , exist (N is the number of degrees of freedom). As the temperature goes to zero a further 'order by disorder' selection is made from this manifold. The pyrochlore antiferromagnet Er 2 Ti 2 O 7 is believed to have an easy plane anisotropy and is reported to have the same magnetic structure. This is perhaps surprising, given that the dipole interaction lifts the degeneracy of the classical model in favour of a different structure. We interpret our results in the light of these facts

  9. Study of Spin and Decay-Plane Correlations of W Bosons in the $e^{+} e^{-} \\to W^{+} W^{-}$ Process at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, G J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Echenard, B; Eline, A; El-Hage, A; El-Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, F; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kraber, M; Krämer, R W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Novák, T; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosemann, C; Rosenbleck, C; Rosier-Lees, S; Roth, S; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; Schotanus, D J; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, L; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, Q; Wang, X L; Wang, Z M; Weber, M; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2005-01-01

    Data collected at LEP at centre-of-mass energies \\sqrt(s) = 189 - 209 GeV are used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~ events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events. Decay-plane correlations, consistent with zero and with the Standard Model predictions, are measured.

  10. Misjudging frustrations in spin liquids from oversimplified use of Curie-Weiss law

    Energy Technology Data Exchange (ETDEWEB)

    Nag, Abhishek, E-mail: msan@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Ray, Sugata [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Centre for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2017-02-15

    Absence of a single smoking-gun experiment to identify a quantum spin liquid, has kept their characterisation difficult till date. Featureless dc magnetic susceptibility and large antiferromagnetic frustration are always considered as the essential pointers to these systems. However, we show that the amount of frustration estimated by using generalised Curie-Weiss law on these susceptibility data are prone to errors and thus should be dealt with caution. We measure and analyse susceptibility data of Ba{sub 3}ZnIr{sub 2}O{sub 9}, a spin orbital liquid candidate and Gd{sub 2}O{sub 3}, a 1.5 K antiferromagnet and show the distinguishing features between them. A continuous and significant change in Curie and Weiss constants is seen to take place in Ba{sub 3}ZnIr{sub 2}O{sub 9} and other reported spin liquids with the change in the range of fitting temperatures showing the need of a temperature ‘range-of-fit’ analysis before commenting on the Weiss constants of spin liquids. The variation observed is similar to fluctuations among topological sectors persisting over a range of temperature in spin-ice candidates. On the other hand, even though we find correlations to exist at even 100 times the ordering temperature in Gd{sub 2}O{sub 3}, no such fluctuation is observed which may be used as an additional distinguishing signature of spin liquids over similarly featureless correlated paramagnets. - Highlights: • Curie-Weiss fitting may give erroneous frustration parameters in spin-liquids. • The results depend upon choice of fitting method and temperature range used. • More appropriate method is to use a ʽrange of fit’ analysis. • Can distinguish between spin-liquids and correlated paramagnets.

  11. Broken discrete and continuous symmetries in two-dimensional spiral antiferromagnets

    International Nuclear Information System (INIS)

    Mezio, A; Sposetti, C N; Manuel, L O; Trumper, A E

    2013-01-01

    We study the occurrence of symmetry breaking, at zero and finite temperatures, in the J 1 –J 3 antiferromagnetic Heisenberg model on the square lattice using Schwinger boson mean field theory. For spin- 1/2 the ground state always breaks the SU(2) symmetry with a continuous quasi-critical transition at J 3 /J 1 ∼ 0.38, from Néel to spiral long range order, although local spin fluctuation considerations suggest an intermediate disordered regime around 0.35 ≲ J 3 /J 1 ≲ 0.5, in qualitative agreement with recent numerical results. At low temperatures we find a Z 2 broken symmetry region with short range spiral order characterized by an Ising-like nematic order parameter that compares qualitatively well with classical Monte Carlo results. At intermediate temperatures the phase diagram shows regions with collinear short range orders: for J 3 /J 1 3 /J 1 > 1 a novel phase consisting of four decoupled third neighbour sublattices with Néel (π,π) correlations in each one. We conclude that the effect of quantum and thermal fluctuations is to favour collinear correlations even in the strongly frustrated regime. (paper)

  12. Broken discrete and continuous symmetries in two-dimensional spiral antiferromagnets

    Science.gov (United States)

    Mezio, A.; Sposetti, C. N.; Manuel, L. O.; Trumper, A. E.

    2013-11-01

    We study the occurrence of symmetry breaking, at zero and finite temperatures, in the J1-J3 antiferromagnetic Heisenberg model on the square lattice using Schwinger boson mean field theory. For spin-\\frac{1}{2} the ground state always breaks the SU(2) symmetry with a continuous quasi-critical transition at J3/J1 ˜ 0.38, from Néel to spiral long range order, although local spin fluctuation considerations suggest an intermediate disordered regime around 0.35 ≲ J3/J1 ≲ 0.5, in qualitative agreement with recent numerical results. At low temperatures we find a Z2 broken symmetry region with short range spiral order characterized by an Ising-like nematic order parameter that compares qualitatively well with classical Monte Carlo results. At intermediate temperatures the phase diagram shows regions with collinear short range orders: for J3/J1 1 a novel phase consisting of four decoupled third neighbour sublattices with Néel (π,π) correlations in each one. We conclude that the effect of quantum and thermal fluctuations is to favour collinear correlations even in the strongly frustrated regime.

  13. Persistent low-temperature spin dynamics in the mixed-valence iridate Ba3InIr2O9

    Science.gov (United States)

    Dey, Tusharkanti; Majumder, M.; Orain, J. C.; Senyshyn, A.; Prinz-Zwick, M.; Bachus, S.; Tokiwa, Y.; Bert, F.; Khuntia, P.; Büttgen, N.; Tsirlin, A. A.; Gegenwart, P.

    2017-11-01

    Using thermodynamic measurements, neutron diffraction, nuclear magnetic resonance, and muon spin relaxation, we establish putative quantum spin-liquid behavior in Ba3InIr2O9 , where unpaired electrons are localized on mixed-valence Ir2O9 dimers with Ir4.5 + ions. Despite the antiferromagnetic Curie-Weiss temperature on the order of 10 K, neither long-range magnetic order nor spin freezing are observed down to at least 20 mK, such that spins are short-range correlated and dynamic over nearly three decades in temperature. Quadratic power-law behavior of both the spin-lattice relaxation rate and specific heat indicates the gapless nature of the ground state. We envisage that this exotic behavior may be related to an unprecedented combination of the triangular and buckled honeycomb geometries of nearest-neighbor exchange couplings in the mixed-valence setting.

  14. Anomalous Hall-like effect probe of antiferromagnetic domain wall.

    Science.gov (United States)

    Lang, Lili; Qiu, Xuepeng; Zhou, Shiming

    2018-01-10

    Of crucial importance to antiferromagnetic (AF) spintronic devices, AF domain wall (AFDW), created in exchange biased Y 3 Fe 5 O 12 /Ni 0.50 Co 0.50 O (NiCoO)/Pt, is characterized by anomalous Hall-like effect through magnetic proximity effect and spin Hall magnetoresistance at NiCoO/Pt interface. The AFDW thickness, in the order of nanometers, has been for the first time proved in experiments to increase with increasing temperature. AF spins within AFDW show the same chirality in decent and ascent branches of ferromagnetic magnetization reversal process. Moreover, the uncompensated magnetic moment at the NiCoO/Pt interface is of perpendicular magnetization anisotropy and changes linearly in magnitude with temperature due to the reduced coordination of the magnetic atoms on the AF surface. This work will help to clarify the mechanism of the spin current propagation in AF materials and fully understand the physics behind exchange bias.

  15. Large anomalous Hall effect in a non-collinear antiferromagnet at room temperature

    Science.gov (United States)

    Nakatsuji, Satoru; Kiyohara, Naoki; Higo, Tomoya

    2015-11-01

    In ferromagnetic conductors, an electric current may induce a transverse voltage drop in zero applied magnetic field: this anomalous Hall effect is observed to be proportional to magnetization, and thus is not usually seen in antiferromagnets in zero field. Recent developments in theory and experiment have provided a framework for understanding the anomalous Hall effect using Berry-phase concepts, and this perspective has led to predictions that, under certain conditions, a large anomalous Hall effect may appear in spin liquids and antiferromagnets without net spin magnetization. Although such a spontaneous Hall effect has now been observed in a spin liquid state, a zero-field anomalous Hall effect has hitherto not been reported for antiferromagnets. Here we report empirical evidence for a large anomalous Hall effect in an antiferromagnet that has vanishingly small magnetization. In particular, we find that Mn3Sn, an antiferromagnet that has a non-collinear 120-degree spin order, exhibits a large anomalous Hall conductivity of around 20 per ohm per centimetre at room temperature and more than 100 per ohm per centimetre at low temperatures, reaching the same order of magnitude as in ferromagnetic metals. Notably, the chiral antiferromagnetic state has a very weak and soft ferromagnetic moment of about 0.002 Bohr magnetons per Mn atom (refs 10, 12), allowing us to switch the sign of the Hall effect with a small magnetic field of around a few hundred oersted. This soft response of the large anomalous Hall effect could be useful for various applications including spintronics—for example, to develop a memory device that produces almost no perturbing stray fields.

  16. Spin lattices of walking droplets

    Science.gov (United States)

    Saenz, Pedro; Pucci, Giuseppe; Goujon, Alexis; Dunkel, Jorn; Bush, John

    2017-11-01

    We present the results of an experimental investigation of the spontaneous emergence of collective behavior in spin lattice of droplets walking on a vibrating fluid bath. The bottom topography consists of relatively deep circular wells that encourage the walking droplets to follow circular trajectories centered at the lattice sites, in one direction or the other. Wave-mediated interactions between neighboring drops are enabled through a thin fluid layer between the wells. The sense of rotation of the walking droplets may thus become globally coupled. When the coupling is sufficiently strong, interactions with neighboring droplets may result in switches in spin that lead to preferred global arrangements, including correlated (all drops rotating in the same direction) or anti-correlated (neighboring drops rotating in opposite directions) states. Analogies with ferromagnetism and anti-ferromagnetism are drawn. Different spatial arrangements are presented in 1D and 2D lattices to illustrate the effects of topological frustration. This work was supported by the US National Science Foundation through Grants CMMI-1333242 and DMS-1614043.

  17. A new problem in the correlation of nuclear-spin relaxation and ionic conductivity in superionic glasses

    Science.gov (United States)

    Tatsumisago, M.; Angell, C. A.; Martin, S. W.

    1992-11-01

    Following the recent resolution of the longstanding problem of reconciling constant frequency nuclear-spin lattice relaxation (SLR) activation energies and d.c. conductivity activity energies in ion conducting glasses, we point out a new problem which seems not to have been discussed previously. We report conductivity data measured at a series of fixed frequencies and variable temperatures on a lithium chloroborate glass and compare them with SLR data on identically prepared samples, also using different fixed frequencies. While phenomenological similarities due to comparable departures from exponential relaxation are found in each case, pronounced differences in the most probable relaxation times themselves are observed. The conductivity relaxation at 500 K occurs on a time scale shorter by some 2 orders of magnitude than the 7Li SLR correlation, and has a significantly lower activation energy. We show from a literature review that this distinction is a common but unreported finding for highly decoupled (fast-ion conducting) systems, and that an inverse relationship is found in supercoupled salt/polymer ``solid'' electrolytes. In fast-ion conducting glasses, the slower SLR process would imply special features in the fast-ion motion which permit spin correlations to survive many more successive ion displacements than previously expected. It is conjectured that the SLR in superionic glasses depends on the existence of a class of low-lying traps infrequently visited by migrating ions.

  18. Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate

    Directory of Open Access Journals (Sweden)

    S.M. Moosavi Nejad

    2016-04-01

    Full Text Available Basically, the energy distribution of bottom-flavored hadrons produced through polarized top quark decays t(↑→W++b(→Xb, is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay t(↑→bW+. Here we present, for the first time, the analytical expressions for the O(αs radiative corrections to the differential azimuthal decay rates of the partonic process t(↑→b+W+ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the hadrons produced in polarized top decays. These spin-momentum correlations between the top quark spin and its decay product momenta will allow the detailed studies of the top decay mechanism. Our predictions of the hadron energy distributions also enable us to deepen our knowledge of the hadronization process and to test the universality and scaling violations of the bottom-flavored meson fragmentation functions.

  19. Pairwise NMR experiments for the determination of protein backbone dihedral angle Φ based on cross-correlated spin relaxation

    International Nuclear Information System (INIS)

    Takahashi, Hideo; Shimada, Ichio

    2007-01-01

    Novel cross-correlated spin relaxation (CCR) experiments are described, which measure pairwise CCR rates for obtaining peptide dihedral angles Φ. The experiments utilize intra-HNCA type coherence transfer to refocus 2-bond J NCα coupling evolution and generate the N (i)-C α (i) or C'(i-1)-C α (i) multiple quantum coherences which are required for measuring the desired CCR rates. The contribution from other coherences is also discussed and an appropriate setting of the evolution delays is presented. These CCR experiments were applied to 15 N- and 13 C-labeled human ubiquitin. The relevant CCR rates showed a high degree of correlation with the Φ angles observed in the X-ray structure. By utilizing these CCR experiments in combination with those previously established for obtaining dihedral angle Ψ, we can determine high resolution structures of peptides that bind weakly to large target molecules

  20. Angular Correlations Between Fragment Spin and Prompt Neutron Evaporation in Spontaneous Fission of 252Cf: CORA-Demon Experiment

    Science.gov (United States)

    Prokhorova, E.; Gönnenwein, F.; Kopatch, Yu.; Mutterer, M.; Hanappe, F.; Kinnard, V.; Stuttgé, L.; Dorvaux, O.; Wollersheim, H.-J.

    2007-05-01

    A novel method to search for the anisotropic emission of prompt neutrons in the center-of-mass system of fission fragments is presented. The anisotropy is conjectured to be due to the large spins of fission fragments are known to carry. Triple neutron- neutron-fragment correlations in spontaneous fission of 252Cf were investigated in an exploratory experiment dubbed CORA-DEMON experiment. Fission fragments were intercepted in a double ionization chamber while neutrons were spotted in 2 two-dimensional cylindrical walls of Demon detectors with the target on the vertical cylinder axis. A new method of analysis of triple angular correlations between 2 neutrons and a fission fragment was applied. Preliminary results are reported.

  1. 't Hooft-Polyakov monopoles in an antiferromagnetic Bose-Einstein condensate

    NARCIS (Netherlands)

    Stoof, H.T.C.; Vliegen, E.; Al Khawaja, U.

    2001-01-01

    We show that an antiferromagnetic spin-1 Bose-Einstein condensate, which can for instance be created with 23-Na atoms in an optical trap, has not only singular line-like vortex excitations, but also allows for singular point-like topological excitations, i.e., 't Hooft-Polyakov monopoles. We discuss

  2. The dynamical frustration of interlayer excitons delocalizing in bilayer quantum antiferromagnets

    NARCIS (Netherlands)

    Rademaker, L.; Wu, K.; Hilgenkamp, H.; Zaanen, J.

    2012-01-01

    Using the self-consistent Born approximation we study the delocalization of interlayer excitons in the bilayer Heisenberg quantum antiferromagnet. Under realistic conditions we find that the coupling between the exciton motion and the spin system is strongly enhanced as compared to the case of a

  3. Construction and study of exact ground states for a class of quantum antiferromagnets

    International Nuclear Information System (INIS)

    Fannes, M.

    1989-01-01

    Techniques of quantum probability are used to construct the exact ground states for a class of quantum spin systems in one dimension. This class in particular contains the antiferromagnetic models introduced by various authors under the name of VBS-models. The construction permits a detailed study of these ground states. (A.C.A.S.) [pt

  4. How to manipulate magnetic states of antiferromagnets

    Science.gov (United States)

    Song, Cheng; You, Yunfeng; Chen, Xianzhe; Zhou, Xiaofeng; Wang, Yuyan; Pan, Feng

    2018-03-01

    Antiferromagnetic materials, which have drawn considerable attention recently, have fascinating features: they are robust against perturbation, produce no stray fields, and exhibit ultrafast dynamics. Discerning how to efficiently manipulate the magnetic state of an antiferromagnet is key to the development of antiferromagnetic spintronics. In this review, we introduce four main methods (magnetic, strain, electrical, and optical) to mediate the magnetic states and elaborate on intrinsic origins of different antiferromagnetic materials. Magnetic control includes a strong magnetic field, exchange bias, and field cooling, which are traditional and basic. Strain control involves the magnetic anisotropy effect or metamagnetic transition. Electrical control can be divided into two parts, electric field and electric current, both of which are convenient for practical applications. Optical control includes thermal and electronic excitation, an inertia-driven mechanism, and terahertz laser control, with the potential for ultrafast antiferromagnetic manipulation. This review sheds light on effective usage of antiferromagnets and provides a new perspective on antiferromagnetic spintronics.

  5. Observation of spin correlation in $t\\overline{t}$ events from $pp$ collisions at $\\sqrt{s}$ = 7 TeV using the ATLAS detector

    CERN Document Server

    Aad, Georges; Abdallah, Jalal; Abdel Khalek, Samah; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Aderholz, Michael; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allbrooke, Benedict; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral, Pedro; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amorós, Gabriel; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Andrieux, Marie-Laure; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Astvatsatourov, Anatoli; Aubert, Bernard; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barashkou, Andrei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Sebastian; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Behera, Prafulla; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Benchouk, Chafik; Bendel, Markus; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertella, Claudia; Bertin, Antonio; Bertinelli, Francesco; Bertolucci, Federico; Besana, Maria Ilaria; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blanchot, Georges; Blazek, Tomas; Blocker, Craig; Blocki, Jacek; Blondel, Alain; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Boddy, Christopher Richard; Boehler, Michael; Boek, Jennifer; Boelaert, Nele; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Bolnet, Nayanka Myriam; Bomben, Marco; Bona, Marcella; Bondarenko, Valery; Bondioli, Mario; Boonekamp, Maarten; Booth, Chris; Bordoni, Stefania; Borer, Claudia; Borisov, Anatoly; Borissov, Guennadi; Borjanovic, Iris; Borri, Marcello; Borroni, Sara; Bortolotto, Valerio; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Botterill, David; Bouchami, Jihene; Boudreau, Joseph; Bouhova-Thacker, Evelina Vassileva; Boumediene, Djamel Eddine; Bourdarios, Claire; Bousson, Nicolas; Boveia, Antonio; Boyd, James; Boyko, Igor; Bozhko, Nikolay; Bozovic-Jelisavcic, Ivanka; Bracinik, Juraj; Braem, André; Branchini, Paolo; Brandenburg, George; Brandt, Andrew; Brandt, Gerhard; Brandt, Oleg; Bratzler, Uwe; Brau, Benjamin; Brau, James; Braun, Helmut; Brelier, Bertrand; Bremer, Johan; Brendlinger, Kurt; Brenner, Richard; Bressler, Shikma; Britton, Dave; Brochu, Frederic; Brock, Ian; Brock, Raymond; Brodbeck, Timothy; Brodet, Eyal; Broggi, Francesco; Bromberg, Carl; Bronner, Johanna; Brooijmans, Gustaaf; Brooks, William; Brown, Gareth; Brown, Heather; Bruckman de Renstrom, Pawel; Bruncko, Dusan; Bruneliere, Renaud; Brunet, Sylvie; Bruni, Alessia; Bruni, Graziano; Bruschi, Marco; Buanes, Trygve; Buat, Quentin; Bucci, Francesca; Buchanan, James; Buchanan, Norman; Buchholz, Peter; Buckingham, Ryan; Buckley, Andrew; Buda, Stelian Ioan; Budagov, Ioulian; Budick, Burton; Büscher, Volker; Bugge, Lars; Bulekov, Oleg; Bunse, Moritz; Buran, Torleiv; Burckhart, Helfried; Burdin, Sergey; Burgess, Thomas; Burke, Stephen; Busato, Emmanuel; Bussey, Peter; Buszello, Claus-Peter; Butin, François; Butler, Bart; Butler, John; Buttar, Craig; Butterworth, Jonathan; Buttinger, William; Cabrera Urbán, Susana; Caforio, Davide; Cakir, Orhan; Calafiura, Paolo; Calderini, Giovanni; Calfayan, Philippe; Calkins, Robert; Caloba, Luiz; Caloi, Rita; Calvet, David; Calvet, Samuel; Camacho Toro, Reina; Camarri, Paolo; Cambiaghi, Mario; Cameron, David; Caminada, Lea Michaela; Campana, Simone; Campanelli, Mario; Canale, Vincenzo; Canelli, Florencia; Canepa, Anadi; Cantero, Josu; Capasso, Luciano; Capeans Garrido, Maria Del Mar; Caprini, Irinel; Caprini, Mihai; Capriotti, Daniele; Capua, Marcella; Caputo, Regina; Cardarelli, Roberto; Carli, Tancredi; Carlino, Gianpaolo; Carminati, Leonardo; Caron, Bryan; Caron, Sascha; Carquin, Edson; Carrillo Montoya, German D; Carter, Antony; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Cascella, Michele; Caso, Carlo; Castaneda Hernandez, Alfredo Martin; Castaneda-Miranda, Elizabeth; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Cataldi, Gabriella; Cataneo, Fernando; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cauz, Diego; Cavalleri, Pietro; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Ceradini, Filippo; Santiago Cerqueira, Augusto; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cetin, Serkant Ali; Cevenini, Francesco; Chafaq, Aziz; Chakraborty, Dhiman; Chan, Kevin; Chapleau, Bertrand; Chapman, John Derek; Chapman, John Wehrley; Chareyre, Eve; Charlton, Dave; Chavda, Vikash; Chavez Barajas, Carlos Alberto; Cheatham, Susan; Chekanov, Sergei; Chekulaev, Sergey; Chelkov, Gueorgui; Chelstowska, Magda Anna; Chen, Chunhui; Chen, Hucheng; Chen, Shenjian; Chen, Tingyang; Chen, Xin; Cheng, Shaochen; Cheplakov, Alexander; Chepurnov, Vladimir; Cherkaoui El Moursli, Rajaa; Chernyatin, Valeriy; Cheu, Elliott; Cheung, Sing-Leung; Chevalier, Laurent; Chiefari, Giovanni; Chikovani, Leila; Childers, John Taylor; Chilingarov, Alexandre; Chiodini, Gabriele; Chisholm, Andrew; Chislett, Rebecca Thalatta; Chizhov, Mihail; Choudalakis, Georgios; Chouridou, Sofia; Christidi, Illectra-Athanasia; Christov, Asen; Chromek-Burckhart, Doris; Chu, Ming-Lee; Chudoba, Jiri; Ciapetti, Guido; Ciftci, Abbas Kenan; Ciftci, Rena; Cinca, Diane; Cindro, Vladimir; Ciobotaru, Matei Dan; Ciocca, Claudia; Ciocio, Alessandra; Cirilli, Manuela; Citterio, Mauro; Ciubancan, Mihai; Clark, Allan G; Clark, Philip James; Cleland, Bill; Clemens, Jean-Claude; Clement, Benoit; Clement, Christophe; Clifft, Roger; Coadou, Yann; Cobal, Marina; Coccaro, Andrea; Cochran, James H; Coe, Paul; Cogan, Joshua Godfrey; Coggeshall, James; Cogneras, Eric; Colas, Jacques; Colijn, Auke-Pieter; Collins, Neil; Collins-Tooth, Christopher; Collot, Johann; Colon, German; Conde Muiño, Patricia; Coniavitis, Elias; Conidi, Maria Chiara; Consonni, Michele; Consonni, Sofia Maria; Consorti, Valerio; Constantinescu, Serban; Conta, Claudio; Conti, Geraldine; Conventi, Francesco; Cook, James; Cooke, Mark; Cooper, Ben; Cooper-Sarkar, Amanda; Copic, Katherine; Cornelissen, Thijs; Corradi, Massimo; Corriveau, Francois; Cortes-Gonzalez, Arely; Cortiana, Giorgio; Costa, Giuseppe; Costa, María José; Costanzo, Davide; Costin, Tudor; Côté, David; Coura Torres, Rodrigo; Courneyea, Lorraine; Cowan, Glen; Cowden, Christopher; Cox, Brian; Cranmer, Kyle; Crescioli, Francesco; Cristinziani, Markus; Crosetti, Giovanni; Crupi, Roberto; Crépé-Renaudin, Sabine; Cuciuc, Constantin-Mihai; Cuenca Almenar, Cristóbal; Cuhadar Donszelmann, Tulay; Curatolo, Maria; Curtis, Chris; Cuthbert, Cameron; Cwetanski, Peter; Czirr, Hendrik; Czodrowski, Patrick; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; D'Orazio, Alessia; Da Silva, Paulo Vitor; Da Via, Cinzia; Dabrowski, Wladyslaw; Dafinca, Alexandru; Dai, Tiesheng; Dallapiccola, Carlo; Dam, Mogens; Dameri, Mauro; Damiani, Daniel; Danielsson, Hans Olof; Dannheim, Dominik; Dao, Valerio; Darbo, Giovanni; Darlea, Georgiana Lavinia; Davey, Will; Davidek, Tomas; Davidson, Nadia; Davidson, Ruth; Davies, Eleanor; Davies, Merlin; Davison, Adam; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Dawson, John; Daya-Ishmukhametova, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Castro Faria Salgado, Pedro; De Cecco, Sandro; de Graat, Julien; De Groot, Nicolo; de Jong, Paul; De La Taille, Christophe; De la Torre, Hector; De Lotto, Barbara; de Mora, Lee; De Nooij, Lucie; De Pedis, Daniele; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; De Zorzi, Guido; Dean, Simon; Dearnaley, William James; Debbe, Ramiro; Debenedetti, Chiara; Dechenaux, Benjamin; Dedovich, Dmitri; Degenhardt, James; Dehchar, Mohamed; Del Papa, Carlo; Del Peso, Jose; Del Prete, Tarcisio; Delemontex, Thomas; Deliyergiyev, Maksym; Dell'Acqua, Andrea; Dell'Asta, Lidia; Della Pietra, Massimo; della Volpe, Domenico; Delmastro, Marco; Delruelle, Nicolas; Delsart, Pierre-Antoine; Deluca, Carolina; Demers, Sarah; Demichev, Mikhail; Demirkoz, Bilge; Deng, Jianrong; Denisov, Sergey; Derendarz, Dominik; Derkaoui, Jamal Eddine; Derue, Frederic; Dervan, Paul; Desch, Klaus Kurt; Devetak, Erik; Deviveiros, Pier-Olivier; Dewhurst, Alastair; DeWilde, Burton; Dhaliwal, Saminder; Dhullipudi, Ramasudhakar; Di Ciaccio, Anna; Di Ciaccio, Lucia; Di Girolamo, Alessandro; Di Girolamo, Beniamino; Di Luise, Silvestro; Di Mattia, Alessandro; Di Micco, Biagio; Di Nardo, Roberto; Di Simone, Andrea; Di Sipio, Riccardo; Diaz, Marco Aurelio; Diblen, Faruk; Diehl, Edward; Dietrich, Janet; Dietzsch, Thorsten; Diglio, Sara; Dindar Yagci, Kamile; Dingfelder, Jochen; Dionisi, Carlo; Dita, Petre; Dita, Sanda; Dittus, Fridolin; Djama, Fares; Djobava, Tamar; Barros do Vale, Maria Aline; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobbs, Matt; Dobinson, Robert; Dobos, Daniel; Dobson, Ellie; Dodd, Jeremy; Doglioni, Caterina; Doherty, Tom; Doi, Yoshikuni; Dolejsi, Jiri; Dolenc, Irena; Dolezal, Zdenek; Dolgoshein, Boris; Dohmae, Takeshi; Donadelli, Marisilvia; Donega, Mauro; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dos Anjos, Andre; Dosil, Mireia; Dotti, Andrea; Dova, Maria-Teresa; Dowell, John; Doxiadis, Alexander; Doyle, Tony; Drasal, Zbynek; Drees, Jürgen; Dressnandt, Nandor; Drevermann, Hans; Driouichi, Chafik; Dris, Manolis; Dubbert, Jörg; Dube, Sourabh; Duchovni, Ehud; Duckeck, Guenter; Dudarev, Alexey; Dudziak, Fanny; Dührssen, Michael; Duerdoth, Ian; Duflot, Laurent; Dufour, Marc-Andre; Dunford, Monica; Duran Yildiz, Hatice; Duxfield, Robert; Dwuznik, Michal; Dydak, Friedrich; Düren, Michael; Ebenstein, William; Ebke, Johannes; Eckweiler, Sebastian; Edmonds, Keith; Edwards, Clive; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Ehrich, Thies; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Eisenhandler, Eric; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Katherine; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Emeliyanov, Dmitry; Engelmann, Roderich; Engl, Albert; Epp, Brigitte; Eppig, Andrew; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Escobar, Carlos; Espinal Curull, Xavier; Esposito, Bellisario; Etienne, Francois; Etienvre, Anne-Isabelle; Etzion, Erez; Evangelakou, Despoina; Evans, Hal; Fabbri, Laura; Fabre, Caroline; Fakhrutdinov, Rinat; Falciano, Speranza; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farley, Jason; Farooque, Trisha; Farrell, Steven; Farrington, Sinead; Farthouat, Philippe; Fassnacht, Patrick; Fassouliotis, Dimitrios; Fatholahzadeh, Baharak; Favareto, Andrea; Fayard, Louis; Fazio, Salvatore; Febbraro, Renato; Federic, Pavol; Fedin, Oleg; Fedorko, Woiciech; Fehling-Kaschek, Mirjam; Feligioni, Lorenzo; Fellmann, Denis; Feng, Cunfeng; Feng, Eric; Fenyuk, Alexander; Ferencei, Jozef; Ferland, Jonathan; Fernando, Waruna; Ferrag, Samir; Ferrando, James; Ferrara, Valentina; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrer, Maria Lorenza; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filippas, Anastasios; Filthaut, Frank; Fincke-Keeler, Margret; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Gordon; Fischer, Peter; Fisher, Matthew; Flechl, Martin; Fleck, Ivor; Fleckner, Johanna; Fleischmann, Philipp; Fleischmann, Sebastian; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Flowerdew, Michael; Fokitis, Manolis; Fonseca Martin, Teresa; Forbush, David Alan; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Foster, Joe; Fournier, Daniel; Foussat, Arnaud; Fowler, Andrew; Fowler, Ken; Fox, Harald; Francavilla, Paolo; Franchino, Silvia; Francis, David; Frank, Tal; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; Fratina, Sasa; French, Sky; Friedrich, Felix; Froeschl, Robert; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gadfort, Thomas; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Gan, KK; Gao, Yongsheng; Gapienko, Vladimir; Gaponenko, Andrei; Garberson, Ford; Garcia-Sciveres, Maurice; García, Carmen; García Navarro, José Enrique; Gardner, Robert; Garelli, Nicoletta; Garitaonandia, Hegoi; Garonne, Vincent; Garvey, John; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gauzzi, Paolo; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gayde, Jean-Christophe; Gazis, Evangelos; Ge, Peng; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerlach, Peter; Gershon, Avi; Geweniger, Christoph; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giakoumopoulou, Victoria; Giangiobbe, Vincent; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Adam; Gibson, Stephen; Gilbert, Laura; Gilewsky, Valentin; Gillberg, Dag; Gillman, Tony; Gingrich, Douglas; Ginzburg, Jonatan; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Francesco Michelangelo; Giovannini, Paola; Giraud, Pierre-Francois; Giugni, Danilo; Giunta, Michele; Giusti, Paolo; Gjelsten, Børge Kile; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glazov, Alexandre; Glitza, Karl-Walter; Glonti, George; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goebel, Martin; Göpfert, Thomas; Goeringer, Christian; Gössling, Claus; Göttfert, Tobias; Goldfarb, Steven; Golling, Tobias; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; Gonidec, Allain; Gonzalez, Saul; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez Silva, Laura; Gonzalez-Sevilla, Sergio; Goodson, Jeremiah Jet; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorfine, Grant; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Gorokhov, Serguei; Goryachev, Vladimir; Gosdzik, Bjoern; Gosselink, Martijn; Gostkin, Mikhail Ivanovitch; Gough Eschrich, Ivo; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Grancagnolo, Francesco; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Grau, Nathan; Gray, Heather; Gray, Julia Ann; Graziani, Enrico; Grebenyuk, Oleg; Greenshaw, Timothy; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grigalashvili, Nugzar; Grillo, Alexander; Grinstein, Sebastian; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Groh, Manfred; Gross, Eilam; Grosse-Knetter, Joern; Groth-Jensen, Jacob; Grybel, Kai; Guarino, Victor; Guest, Daniel; Guicheney, Christophe; Guida, Angelo; Guindon, Stefan; Guler, Hulya; Gunther, Jaroslav; Guo, Bin; Guo, Jun; Gupta, Ambreesh; Gusakov, Yury; Gushchin, Vladimir; Gutierrez, Phillip; Guttman, Nir; Gutzwiller, Olivier; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haas, Stefan; Haber, Carl; Hadavand, Haleh Khani; Hadley, David; Haefner, Petra; Hahn, Ferdinand; Haider, Stefan; Hajduk, Zbigniew; Hakobyan, Hrachya; Hall, David; Haller, Johannes; Hamacher, Klaus; Hamal, Petr; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Han, Hongguang; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Handel, Carsten; Hanke, Paul; Hansen, John Renner; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hansson, Per; Hara, Kazuhiko; Hare, Gabriel; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Karl; Hartert, Jochen; Hartjes, Fred; Haruyama, Tomiyoshi; Harvey, Alex; Hasegawa, Satoshi; Hasegawa, Yoji; Hassani, Samira; Hatch, Mark; Hauff, Dieter; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawes, Brian; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hawkins, Donovan; Hayakawa, Takashi; Hayashi, Takayasu; Hayden, Daniel; Hayward, Helen; Haywood, Stephen; Hazen, Eric; He, Mao; Head, Simon; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heinemann, Beate; Heisterkamp, Simon; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, Robert; Henke, Michael; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Henry-Couannier, Frédéric; Hensel, Carsten; Henß, Tobias; Medina Hernandez, Carlos; Hernández Jiménez, Yesenia; Herrberg, Ruth; Hershenhorn, Alon David; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Higón-Rodriguez, Emilio; Hill, Daniel; Hill, John; Hill, Norman; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirsch, Florian; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hohlfeld, Marc; Holder, Martin; Holmgren, Sven-Olof; Holy, Tomas; Holzbauer, Jenny; Homma, Yasuhiro; Hong, Tae Min; Hooft van Huysduynen, Loek; Horazdovsky, Tomas; Horn, Claus; Horner, Stephan; Hostachy, Jean-Yves; Hou, Suen; Houlden, Michael; Hoummada, Abdeslam; Howarth, James; Howell, David; Hristova, Ivana; Hrivnac, Julius; Hruska, Ivan; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Huang, Guang Shun; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huettmann, Antje; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Hughes-Jones, Richard; Huhtinen, Mika; Hurst, Peter; Hurwitz, Martina; Husemann, Ulrich; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibbotson, Michael; Ibragimov, Iskander; Ichimiya, Ryo; Iconomidou-Fayard, Lydia; Idarraga, John; Iengo, Paolo; Igonkina, Olga; Ikegami, Yoichi; Ikeno, Masahiro; Ilchenko, Yuri; Iliadis, Dimitrios; Ilic, Nikolina; Imori, Masatoshi; Ince, Tayfun; Inigo-Golfin, Joaquin; Ioannou, Pavlos; Iodice, Mauro; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishikawa, Akimasa; Ishino, Masaya; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakubek, Jan; Jana, Dilip; Jankowski, Ernest; Jansen, Eric; Jansen, Hendrik; Jantsch, Andreas; Janus, Michel; Jarlskog, Göran; Jeanty, Laura; Jelen, Kazimierz; Jen-La Plante, Imai; Jenni, Peter; Jeremie, Andrea; Jež, Pavel; Jézéquel, Stéphane; Jha, Manoj Kumar; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Ge; Jin, Shan; Jinnouchi, Osamu; Joergensen, Morten Dam; Joffe, David; Johansen, Lars; Johansen, Marianne; Johansson, Erik; Johansson, Per; Johnert, Sebastian; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tegid; Jones, Tim; Jonsson, Ove; Joram, Christian; Jorge, Pedro; Joseph, John; Jovicevic, Jelena; Jovin, Tatjana; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Juranek, Vojtech; Jussel, Patrick; Juste Rozas, Aurelio; Kabachenko, Vasily; Kabana, Sonja; Kaci, Mohammed; Kaczmarska, Anna; Kadlecik, Peter; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kaiser, Steffen; Kajomovitz, Enrique; Kalinin, Sergey; Kalinovskaya, Lidia; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kaplon, Jan; Kar, Deepak; Karagounis, Michael; Karagoz, Muge; Karnevskiy, Mikhail; Karr, Kristo; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Mayuko; Kataoka, Yousuke; Katsoufis, Elias; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kayl, Manuel; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Kehoe, Robert; Keil, Markus; Kekelidze, George; Keller, John; Kennedy, John; Kenyon, Mike; Kepka, Oldrich; Kerschen, Nicolas; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Kharchenko, Dmitri; Khodinov, Alexander; Kholodenko, Anatoli; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Nikolai; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hyeon Jin; Kim, Min Suk; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; Kirk, Julie; Kirsch, Lawrence; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kittelmann, Thomas; Kiver, Andrey; Kladiva, Eduard; Klaiber-Lodewigs, Jonas; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klemetti, Miika; Klier, Amit; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klinkby, Esben; Klioutchnikova, Tatiana; Klok, Peter; Klous, Sander; Kluge, Eike-Erik; Kluge, Thomas; Kluit, Peter; Kluth, Stefan; Knecht, Neil; Kneringer, Emmerich; Knobloch, Juergen; Knoops, Edith; Knue, Andrea; Ko, Byeong Rok; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Köneke, Karsten; König, Adriaan; Koenig, Sebastian; Köpke, Lutz; Koetsveld, Folkert; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohn, Fabian; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kokott, Thomas; Kolachev, Guennady; Kolanoski, Hermann; Kolesnikov, Vladimir; Koletsou, Iro; Koll, James; Kollefrath, Michael; Kolya, Scott; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kono, Takanori; Kononov, Anatoly; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kootz, Andreas; Koperny, Stefan; Korcyl, Krzysztof; Kordas, Kostantinos; Koreshev, Victor; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotamäki, Miikka Juhani; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, James; Kraus, Jana; Kreisel, Arik; Krejci, Frantisek; Kretzschmar, Jan; Krieger, Nina; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruth, Andre; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Thorsten; Kuhn, Dietmar; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kummer, Christian; Kuna, Marine; Kundu, Nikhil; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurata, Masakazu; Kurochkin, Yurii; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; Kwee, Regina; La Rosa, Alessandro; La Rotonda, Laura; Labarga, Luis; Labbe, Julien; Lablak, Said; Lacasta, Carlos; Lacava, Francesco; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laisne, Emmanuel; Lamanna, Massimo; Lambourne, Luke; Lampen, Caleb; Lampl, Walter; Lancon, Eric; Landgraf, Ulrich; Landon, Murrough; Lane, Jenna; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Larionov, Anatoly; Larner, Aimee; Lasseur, Christian; Lassnig, Mario; Laurelli, Paolo; Lavorini, Vincenzo; Lavrijsen, Wim; Laycock, Paul; Lazarev, Alexandre; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Maner, Christophe; Le Menedeu, Eve; Lebel, Céline; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Michel; Legendre, Marie; Leger, Annie; LeGeyt, Benjamin; Legger, Federica; Leggett, Charles; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Leltchouk, Mikhail; Lemmer, Boris; Lendermann, Victor; Leney, Katharine; Lenz, Tatiana; Lenzen, Georg; Lenzi, Bruno; Leonhardt, Kathrin; Leontsinis, Stefanos; Leroy, Claude; Lessard, Jean-Raphael; Lesser, Jonas; Lester, Christopher; Leung Fook Cheong, Annabelle; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levitski, Mikhail; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bo; Li, Haifeng; Li, Shu; Li, Xuefei; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lichtnecker, Markus; Lie, Ki; Liebig, Wolfgang; Lifshitz, Ronen; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Linnemann, James; Lipeles, Elliot; Lipinsky, Lukas; Lipniacka, Anna; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Chuanlei; Liu, Dong; Liu, Hao; Liu, Jianbei; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Loken, James; Lombardo, Vincenzo Paolo; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lo Sterzo, Francesco; Losty, Michael; Lou, Xinchou; Lounis, Abdenour; Loureiro, Karina; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Ludwig, Andreas; Ludwig, Dörthe; Ludwig, Inga; Ludwig, Jens; Luehring, Frederick; Luijckx, Guy; Lukas, Wolfgang; Lumb, Debra; Luminari, Lamberto; Lund, Esben; Lund-Jensen, Bengt; Lundberg, Björn; Lundberg, Johan; Lundquist, Johan; Lungwitz, Matthias; Lutz, Gerhard; Lynn, David; Lys, Jeremy; Lytken, Else; Ma, Hong; Ma, Lian Liang; Macana Goia, Jorge Andres; Maccarrone, Giovanni; Macchiolo, Anna; Maček, Boštjan; Machado Miguens, Joana; Mackeprang, Rasmus; Madaras, Ronald; Mader, Wolfgang; Maenner, Reinhard; Maeno, Tadashi; Mättig, Peter; Mättig, Stefan; Magnoni, Luca; Magradze, Erekle; Mahalalel, Yair; Mahboubi, Kambiz; Mahmoud, Sara; Mahout, Gilles; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Malecki, Piotr; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mameghani, Raphael; Mamuzic, Judita; Manabe, Atsushi; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Mangeard, Pierre-Simon; Manhaes de Andrade Filho, Luciano; Manjavidze, Ioseb; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Manz, Andreas; Mapelli, Alessandro; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchese, Fabrizio; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marroquim, Fernando; Marshall, Robin; Marshall, Zach; Martens, Kalen; Marti-Garcia, Salvador; Martin, Andrew; Martin, Brian; Martin, Brian Thomas; Martin, Franck Francois; Martin, Jean-Pierre; Martin, Philippe; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martin-Haugh, Stewart; Martinez, Mario; Martinez Outschoorn, Verena; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massaro, Graziano; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Matricon, Pierre; Matsumoto, Hiroshi; Matsunaga, Hiroyuki; Matsushita, Takashi; Mattravers, Carly; Maugain, Jean-Marie; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; May, Edward; Mayne, Anna; Mazini, Rachid; Mazur, Michael; Mazzanti, Marcello; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; McGlone, Helen; Mchedlidze, Gvantsa; McLaren, Robert Andrew; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Mechtel, Markus; Medinnis, Mike; Meera-Lebbai, Razzak; Meguro, Tatsuma; Mehdiyev, Rashid; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Mendoza Navas, Luis; Meng, Zhaoxia; Mengarelli, Alberto; Menke, Sven; Menot, Claude; Meoni, Evelin; Mercurio, Kevin Michael; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Meyer, Joerg; Meyer, Thomas Christian; Meyer, W Thomas; Miao, Jiayuan; Michal, Sebastien; Micu, Liliana; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Miller, Robert; Mills, Bill; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Miñano Moya, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Miralles Verge, Lluis; Misiejuk, Andrzej; Mitrevski, Jovan; Mitrofanov, Gennady; Mitsou, Vasiliki A; Mitsui, Shingo; Miyagawa, Paul; Miyazaki, Kazuki; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mockett, Paul; Moed, Shulamit; Moeller, Victoria; Mönig, Klaus; Möser, Nicolas; Mohapatra, Soumya; Mohr, Wolfgang; Mohrdieck-Möck, Susanne; Moisseev, Artemy; Moles-Valls, Regina; Molina-Perez, Jorge; Monk, James; Monnier, Emmanuel; Montesano, Simone; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moorhead, Gareth; Mora Herrera, Clemencia; Moraes, Arthur; Morange, Nicolas; Morel, Julien; Morello, Gianfranco; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Morin, Jerome; Morley, Anthony Keith; Mornacchi, Giuseppe; Morozov, Sergey; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Mudrinic, Mihajlo; Mueller, Felix; Mueller, James; Mueller, Klemens; Müller, Thomas; Mueller, Timo; Muenstermann, Daniel; Muir, Alex; Munwes, Yonathan; Murray, Bill; Mussche, Ido; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nadal, Jordi; Nagai, Koichi; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Nanava, Gizo; Napier, Austin; Narayan, Rohin; Nash, Michael; Nation, Nigel; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Neal, Homer; Nebot, Eduardo; Nechaeva, Polina; Neep, Thomas James; Negri, Andrea; Negri, Guido; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neusiedl, Andrea; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen Thi Hong, Van; Nickerson, Richard; Nicolaidou, Rosy; Nicolas, Ludovic; Nicquevert, Bertrand; Niedercorn, Francois; Nielsen, Jason; Niinikoski, Tapio; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolaev, Kirill; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsen, Henrik; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nishiyama, Tomonori; Nisius, Richard; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Nordberg, Markus; Nordkvist, Bjoern; Norton, Peter; Novakova, Jana; Nozaki, Mitsuaki; Nozka, Libor; Nugent, Ian Michael; Nuncio-Quiroz, Adriana-Elizabeth; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; O'Brien, Brendan Joseph; O'Neale, Steve; O'Neil, Dugan; O'Shea, Val; Oakes, Louise Beth; Oakham, Gerald; Oberlack, Horst; Ocariz, Jose; Ochi, Atsuhiko; Oda, Susumu; Odaka, Shigeru; Odier, Jerome; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohshima, Takayoshi; Ohshita, Hidetoshi; Ohsugi, Takashi; Okada, Shogo; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olcese, Marco; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira, Miguel Alfonso; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olivito, Dominick; Olszewski, Andrzej; Olszowska, Jolanta; Omachi, Chihiro; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Orlov, Iliya; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Osuna, Carlos; Otero y Garzon, Gustavo; Ottersbach, John; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Owen, Simon; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagan Griso, Simone; Paganis, Efstathios; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Paleari, Chiara; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panes, Boris; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Panuskova, Monika; Paolone, Vittorio; Papadelis, Aras; Papadopoulou, Theodora; Paramonov, Alexander; Paredes Hernandez, Daniela; Park, Woochun; Parker, Andy; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pashapour, Shabnaz; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pecsy, Martin; Pedraza Morales, Maria Isabel; Peleganchuk, Sergey; Peng, Haiping; Pengo, Ruggero; Penning, Bjoern; Penson, Alexander; Penwell, John; Perantoni, Marcelo; Perez, Kerstin; Perez Cavalcanti, Tiago; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Perrodo, Pascal; Persembe, Seda; Peshekhonov, Vladimir; Peters, Krisztian; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petschull, Dennis; Petteni, Michele; Pezoa, Raquel; Phan, Anna; Phillips, Peter William; Piacquadio, Giacinto; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piec, Sebastian Marcin; Piegaia, Ricardo; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Ping, Jialun; Pinto, Belmiro; Pirotte, Olivier; Pizio, Caterina; Plamondon, Mathieu; Pleier, Marc-Andre; Pleskach, Anatoly; Plotnikova, Elena; Poblaguev, Andrei; Poddar, Sahill; Podlyski, Fabrice; Poggioli, Luc; Poghosyan, Tatevik; Pohl, Martin; Polci, Francesco; Polesello, Giacomo; Policicchio, Antonio; Polini, Alessandro; Poll, James; Polychronakos, Venetios; Pomarede, Daniel Marc; Pomeroy, Daniel; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Posch, Christoph; Pospelov, Guennady; Pospisil, Stanislav; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Prabhu, Robindra; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Pretzl, Klaus Peter; Pribyl, Lukas; Price, Darren; Price, Joe; Price, Lawrence; Price, Michael John; Prieur, Damien; Primavera, Margherita; Prokofiev, Kirill; Prokoshin, Fedor; Protopopescu, Serban; Proudfoot, James; Prudent, Xavier; Przybycien, Mariusz; Przysiezniak, Helenka; Psoroulas, Serena; Ptacek, Elizabeth; Pueschel, Elisa; Purdham, John; Purohit, Milind; Puzo, Patrick; Pylypchenko, Yuriy; Qian, Jianming; Qian, Zuxuan; Qin, Zhonghua; Quadt, Arnulf; Quarrie, David; Quayle, William; Quinonez, Fernando; Raas, Marcel; Radescu, Voica; Radics, Balint; Radloff, Peter; Rador, Tonguc; Ragusa, Francesco; Rahal, Ghita; Rahimi, Amir; Rahm, David; Rajagopalan, Srinivasan; Rammensee, Michael; Rammes, Marcus; Randle-Conde, Aidan Sean; Randrianarivony, Koloina; Ratoff, Peter; Rauscher, Felix; Rave, Tobias Christian; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Reichold, Armin; Reinherz-Aronis, Erez; Reinsch, Andreas; Reisinger, Ingo; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Reznicek, Pavel; Rezvani, Reyhaneh; Richards, Alexander; Richter, Robert; Richter-Was, Elzbieta; Ridel, Melissa; Rijpstra, Manouk; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Rios, Ryan Randy; Riu, Imma; Rivoltella, Giancesare; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Rocha de Lima, Jose Guilherme; Roda, Chiara; Roda Dos Santos, Denis; Rodriguez, Diego; Roe, Adam; Roe, Shaun; Røhne, Ole; Rojo, Victoria; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romanov, Victor; Romeo, Gaston; Romero Adam, Elena; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Anthony; Rose, Matthew; Rosenbaum, Gabriel; Rosenberg, Eli; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rosselet, Laurent; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexander; Rozen, Yoram; Ruan, Xifeng; Rubinskiy, Igor; Ruckert, Benjamin; Ruckstuhl, Nicole; Rud, Viacheslav; Rudolph, Christian; Rudolph, Gerald; Rühr, Frederik; Ruggieri, Federico; Ruiz-Martinez, Aranzazu; Rumiantsev, Viktor; Rumyantsev, Leonid; Runge, Kay; Rurikova, Zuzana; Rusakovich, Nikolai; Rutherfoord, John; Ruwiedel, Christoph; Ruzicka, Pavel; Ryabov, Yury; Ryadovikov, Vasily; Ryan, Patrick; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Rzaeva, Sevda; Saavedra, Aldo; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Samset, Björn Hallvard; Sanchez, Arturo; Sanchez Martinez, Victoria; Sandaker, Heidi; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandoval, Carlos; Sandstroem, Rikard; Sandvoss, Stephan; Sankey, Dave; Sansoni, Andrea; Santamarina Rios, Cibran; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Saraiva, João; Sarangi, Tapas; Sarkisyan-Grinbaum, Edward; Sarri, Francesca; Sartisohn, Georg; Sasaki, Osamu; Sasao, Noboru; Satsounkevitch, Igor; Sauvage, Gilles; Sauvan, Emmanuel; Sauvan, Jean-Baptiste; Savard, Pierre; Savinov, Vladimir; Savu, Dan Octavian; Sawyer, Lee; Saxon, David; Saxon, James; 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Dean; Schamov, Andrey; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schioppa, Marco; Schlenker, Stefan; Schlereth, James; Schmidt, Evelyn; Schmieden, Kristof; Schmitt, Christian; Schmitt, Sebastian; Schmitz, Martin; Schöning, André; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schram, Malachi; Schroeder, Christian; Schroer, Nicolai; Schuler, Georges; Schultens, Martin Johannes; Schultes, Joachim; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Jan; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwanenberger, Christian; Schwartzman, Ariel; Schwemling, Philippe; Schwienhorst, Reinhard; Schwierz, Rainer; Schwindling, Jerome; Schwindt, Thomas; Schwoerer, Maud; Sciolla, Gabriella; Scott, Bill; Searcy, Jacob; Sedov, George; Sedykh, Evgeny; Segura, Ester; Seidel, Sally; Seiden, Abraham; Seifert, Frank; Seixas, José; Sekhniaidze, Givi; Sekula, Stephen; Selbach, Karoline Elfriede; Seliverstov, Dmitry; 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Skottowe, Hugh Philip; Skovpen, Kirill; Skubic, Patrick; Skvorodnev, Nikolai; Slater, Mark; Slavicek, Tomas; Sliwa, Krzysztof; Sloper, John erik; Smakhtin, Vladimir; Smart, Ben; Smirnov, Sergei; Smirnov, Yury; Smirnova, Lidia; Smirnova, Oxana; Smith, Ben Campbell; Smith, Douglas; Smith, Kenway; Smizanska, Maria; Smolek, Karel; Snesarev, Andrei; Snow, Steve; Snow, Joel; Snuverink, Jochem; Snyder, Scott; Soares, Mara; Sobie, Randall; Sodomka, Jaromir; Soffer, Abner; Solans, Carlos; Solar, Michael; Solc, Jaroslav; Soldatov, Evgeny; Soldevila, Urmila; Solfaroli Camillocci, Elena; Solodkov, Alexander; Solovyanov, Oleg; Soni, Nitesh; Sopko, Vit; Sopko, Bruno; Sosebee, Mark; Soualah, Rachik; Soukharev, Andrey; Spagnolo, Stefania; Spanò, Francesco; Spighi, Roberto; Spigo, Giancarlo; Spila, Federico; Spiwoks, Ralf; Spousta, Martin; Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stanescu-Bellu, Madalina; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staude, Arnold; Stavina, Pavel; Steele, Genevieve; Steinbach, Peter; Steinberg, Peter; Stekl, Ivan; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stern, Sebastian; Stevenson, Kyle; Stewart, Graeme; Stillings, Jan Andre; Stockton, Mark; Stoerig, Kathrin; Stoicea, Gabriel; Stonjek, Stefan; Strachota, Pavel; Stradling, Alden; Straessner, Arno; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strang, Michael; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Strong, John; Stroynowski, Ryszard; Strube, Jan; Stugu, Bjarne; Stumer, Iuliu; Stupak, John; Sturm, Philipp; Styles, Nicholas Adam; Soh, Dart-yin; Su, Dong; Subramania, Halasya Siva; Succurro, Antonella; Sugaya, Yorihito; Sugimoto, Takuya; Suhr, Chad; Suita, Koichi; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Sushkov, Serge; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Suzuki, Yuta; Svatos, Michal; Sviridov, Yuri; Swedish, Stephen; Sykora, Ivan; Sykora, Tomas; Szeless, Balazs; Sánchez, Javier; Ta, Duc; Tackmann, Kerstin; Taffard, Anyes; Tafirout, Reda; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Takubo, Yosuke; Talby, Mossadek; Talyshev, Alexey; Tamsett, Matthew; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanaka, Yoshito; Tanasijczuk, Andres Jorge; Tani, Kazutoshi; Tannoury, Nancy; Tappern, Geoffrey; Tapprogge, Stefan; Tardif, Dominique; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tassi, Enrico; Tatarkhanov, Mous; Tayalati, Yahya; Taylor, Christopher; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teinturier, Marthe; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Terada, Susumu; Terashi, Koji; Terron, Juan; Testa, Marianna; Teuscher, Richard; Thadome, Jocelyn; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thioye, Moustapha; Thoma, Sascha; Thomas, Juergen; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomsen, Lotte Ansgaard; Thomson, Evelyn; Thomson, Mark; Thun, Rudolf; Tian, Feng; Tibbetts, Mark James; Tic, Tomáš; Tikhomirov, Vladimir; Tikhonov, Yury; Timoshenko, Sergey; Tipton, Paul; Tique Aires Viegas, Florbela De Jes; Tisserant, Sylvain; Toczek, Barbara; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokunaga, Kaoru; Tokushuku, Katsuo; Tollefson, Kirsten; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Tong, Guoliang; Tonoyan, Arshak; Topfel, Cyril; Topilin, Nikolai; Torchiani, Ingo; Torrence, Eric; Torres, Heberth; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Trefzger, Thomas; Tremblet, Louis; Tricoli, Alesandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Trinh, Thi Nguyet; Tripiana, Martin; Trischuk, William; Trivedi, Arjun; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiakiris, Menelaos; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsung, Jieh-Wen; Tsuno, Soshi; Tsybychev, Dmitri; Tua, Alan; Tudorache, Alexandra; Tudorache, Valentina; Tuggle, Joseph; Turala, Michal; Turecek, Daniel; Turk Cakir, Ilkay; Turlay, Emmanuel; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Tzanakos, George; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ugland, Maren; Uhlenbrock, Mathias; Uhrmacher, Michael; Ukegawa, Fumihiko; Unal, Guillaume; Underwood, David; Undrus, Alexander; Unel, Gokhan; Unno, Yoshinobu; Urbaniec, Dustin; Usai, Giulio; Uslenghi, Massimiliano; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Vahsen, Sven; Valenta, Jan; Valente, Paolo; Valentinetti, Sara; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; van der Graaf, Harry; van der Kraaij, Erik; Van Der Leeuw, Robin; van der Poel, Egge; van der Ster, Daniel; van Eldik, Niels; van Gemmeren, Peter; van Kesteren, Zdenko; van Vulpen, Ivo; Vanadia, Marco; Vandelli, Wainer; Vandoni, Giovanna; Vaniachine, Alexandre; Vankov, Peter; Vannucci, Francois; Varela Rodriguez, Fernando; Vari, Riccardo; Varnes, Erich; Varol, Tulin; Varouchas, Dimitris; Vartapetian, Armen; Varvell, Kevin; Vassilakopoulos, Vassilios; Vazeille, Francois; Vazquez Schroeder, Tamara; Vegni, Guido; Veillet, Jean-Jacques; Vellidis, Constantine; Veloso, Filipe; Veness, Raymond; Veneziano, Stefano; Ventura, Andrea; Ventura, Daniel; Venturi, Manuela; Venturi, Nicola; Vercesi, Valerio; Verducci, Monica; Verkerke, Wouter; Vermeulen, Jos; Vest, Anja; Vetterli, Michel; Vichou, Irene; Vickey, Trevor; Vickey Boeriu, Oana Elena; Viehhauser, Georg; Viel, Simon; Villa, Mauro; Villaplana Perez, Miguel; Vilucchi, Elisabetta; Vincter, Manuella; Vinek, Elisabeth; Vinogradov, Vladimir; Virchaux, Marc; Virzi, Joseph; Vitells, Ofer; Viti, Michele; Vivarelli, Iacopo; Vives Vaque, Francesc; Vlachos, Sotirios; Vladoiu, Dan; Vlasak, Michal; Vlasov, Nikolai; Vogel, Adrian; Vokac, Petr; Volpi, Guido; Volpi, Matteo; Volpini, Giovanni; von der Schmitt, Hans; von Loeben, Joerg; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorobiev, Alexander; Vorwerk, Volker; Vos, Marcel; Voss, Rudiger; Voss, Thorsten Tobias; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Wagner, Wolfgang; Wagner, Peter; Wahlen, Helmut; Wakabayashi, Jun; Walch, Shannon; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Wang, Chiho; Wang, Haichen; Wang, Hulin; Wang, Jike; Wang, Jin; Wang, Joshua C; Wang, Rui; Wang, Song-Ming; Wang, Tan; Warburton, Andreas; Ward, Patricia; Warsinsky, Markus; Wasicki, Christoph; Watkins, Peter; Watson, Alan; Watson, Ian; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Anthony; Waugh, Ben; Weber, Marc; Weber, Michele; Weber, Pavel; Weidberg, Anthony; Weigell, Philipp; Weingarten, Jens; Weiser, Christian; Wellenstein, Hermann; Wells, Phillippa; Wenaus, Torre; Wendland, Dennis; Wendler, Shanti; Weng, Zhili; Wengler, Thorsten; Wenig, Siegfried; Wermes, Norbert; Werner, Matthias; Werner, Per; Werth, Michael; Wessels, Martin; Wetter, Jeffrey; Weydert, Carole; Whalen, Kathleen; Wheeler-Ellis, Sarah Jane; Whitaker, Scott; White, Andrew; White, Martin; Whitehead, Samuel Robert; Whiteson, Daniel; Whittington, Denver; Wicek, Francois; Wicke, Daniel; Wickens, Fred; Wiedenmann, Werner; Wielers, Monika; Wienemann, Peter; Wiglesworth, Craig; Wiik-Fuchs, Liv Antje Mari; Wijeratne, Peter Alexander; Wildauer, Andreas; Wildt, Martin Andre; Wilhelm, Ivan; Wilkens, Henric George; Will, Jonas Zacharias; Williams, Eric; Williams, Hugh; Willis, William; Willocq, Stephane; Wilson, John; Wilson, Michael Galante; Wilson, Alan; Wingerter-Seez, Isabelle; Winkelmann, Stefan; Winklmeier, Frank; Wittgen, Matthias; Wolter, Marcin Wladyslaw; Wolters, Helmut; Wong, Wei-Cheng; Wooden, Gemma; Wosiek, Barbara; Wotschack, Jorg; Woudstra, Martin; Wozniak, Krzysztof; Wraight, Kenneth; Wright, Catherine; Wright, Michael; Wrona, Bozydar; Wu, Sau Lan; Wu, Xin; Wu, Yusheng; Wulf, Evan; Wunstorf, Renate; Wynne, Benjamin; Xella, Stefania; Xiao, Meng; Xie, Song; Xie, Yigang; Xu, Chao; Xu, Da; Xu, Guofa; Yabsley, Bruce; Yacoob, Sahal; Yamada, Miho; Yamaguchi, Hiroshi; Yamamoto, Akira; Yamamoto, Kyoko; Yamamoto, Shimpei; Yamamura, Taiki; Yamanaka, Takashi; Yamaoka, Jared; Yamazaki, Takayuki; Yamazaki, Yuji; Yan, Zhen; Yang, Haijun; Yang, Un-Ki; Yang, Yi; Yang, Yi; Yang, Zhaoyu; Yanush, Serguei; Yao, Yushu; Yasu, Yoshiji; Ybeles Smit, Gabriel Valentijn; Ye, Jingbo; Ye, Shuwei; Yilmaz, Metin; Yoosoofmiya, Reza; Yorita, Kohei; Yoshida, Riktura; Young, Charles; Youssef, Saul; Yu, Dantong; Yu, Jaehoon; Yu, Jie; Yuan, Li; Yurkewicz, Adam; Zabinski, Bartlomiej; Zaets, Vassilli; Zaidan, Remi; Zaitsev, Alexander; Zajacova, Zuzana; Zanello, Lucia; Zaytsev, Alexander; Zeitnitz, Christian; Zeller, Michael; Zeman, Martin; Zemla, Andrzej; Zendler, Carolin; Zenin, Oleg; Ženiš, Tibor; Zinonos, Zinonas; Zenz, Seth; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhan, Zhichao; Zhang, Dongliang; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Long; Zhao, Tianchi; Zhao, Zhengguo; Zhemchugov, Alexey; Zheng, Shuchen; Zhong, Jiahang; Zhou, Bing; Zhou, Ning; Zhou, Yue; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Junjie; Zhu, Yingchun; Zhuang, Xuai; Zhuravlov, Vadym; Zieminska, Daria; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Ziolkowski, Michael; Zitoun, Robert; Živković, Lidija; Zmouchko, Viatcheslav; Zobernig, Georg; Zoccoli, Antonio; Zolnierowski, Yves; Zsenei, Andras; zur Nedden, Martin; Zutshi, Vishnu; Zwalinski, Lukasz

    2012-01-01

    A measurement of spin correlation in $t\\overline{t}$ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb$^{-1}$. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured degree of correlation corresponds to $A_{helicity} = 0.40^{+0.09}_{-0.08}$, in agreement with the next-to-leading-order Standard Model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.

  6. Two-dimensional magnetism in the triangular antiferromagnet NiGa2S4

    International Nuclear Information System (INIS)

    Nambu, Yusuke

    2013-01-01

    At sufficiently low temperatures, electron spins in normal magnets generally order into some fashion, for instance, ferromagnetic and antiferromagnetic. Geometrical frustration and/or reduced dimensionality can suppress such conventional orders, and occasionally induce unknown states of matter. This is the case for the two-dimensional (2D) triangular antiferromagnet Ni(Ga 2 S 4 , in which S=1 nickel spins do not order, instead show an exotic magnetism. We found (1) a resonant critical slowing down toward T*=8.5 K followed by a viscous spin liquid behavior, and (2) a spin-size dependent ground state. To elucidate (1), spin dynamics ranging from 10 -13 to 10 0 seconds were quantitatively explored through the experimental techniques such as inelastic neutron scattering, backscattering, neutron spin echo, ac and nonlinear susceptibilities. The finding of (2) is evidenced by impurity effects. Integer spins substituted systems such as zinc and iron ions retain a quadratic temperature dependence of the magnetic specific heat as for the parent compound. However, substitutions of half-odd integer spins, cobalt and manganese ions, eventually induce a distinct behavior, indicating an importance of integer size of spins to stabilize the 2D magnetism realized in NiGa 2 S 4 . The article gives our experimental findings and as well as some relevant theoretical scenarios. (author)

  7. Heteronuclear Correlation SSNMR Spectroscopy with Indirect Detection under Fast Magic-Angle Spinning [Book Chapter

    Energy Technology Data Exchange (ETDEWEB)

    Kobayshi, Takeshi [Ames Laboratory (AMES), Ames, IA (United States); Nishiyama, Yusuke [Ames Laboratory (AMES), Ames, IA (United States); Pruski, Marek [Ames Laboratory (AMES), Ames, IA (United States)

    2018-01-01

    The main focus of this chapter is to address experimental strategies on the subject by providing a hands-on guide to fast MAS experiments, with a particular focus on indirect detection. Although our experience is limited to our respective laboratories in Ames and Yokohama, we hope that our descriptions of experimental setups and optimization procedures are sufficiently general to be applicable to all modern instruments. The chapter is organized as follows. Section 2 below introduces briefly the fast MAS technology and its main advantages. In Section 3, we describe the hardware associated with this remarkable technology and provide practical advices on its use, including procedures for loading and unloading the samples, maintaining the probe, reducing t1 noise, etc. In Section 4, we describe the principles and hands-on aspects of experiments involving the indirect detection of spin-1/2 and 14N nuclei

  8. Room-temperature antiferromagnetism in CuMnAs

    Czech Academy of Sciences Publication Activity Database

    Máca, František; Mašek, Jan; Stelmakhovych, O.; Martí, X.; Reichlová, Helena; Uhlířová, K.; Beran, Přemysl; Wadley, P.; Novák, Vít; Jungwirth, Tomáš

    2012-01-01

    Roč. 324, č. 8 (2012), s. 1606-1612 ISSN 0304-8853 R&D Projects: GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet; European Commission(XE) 268066 - 0MSPIN Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521; CEZ:AV0Z10480505 Keywords : antiferromagnetic semiconductors * spintronics * molecular beam epitaxy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012

  9. Determining the short-range spin correlations in the spin-chain Li.sub.2./sub.CuO.sub.2./sub. and CuGeO.sub.3./sub. compounds using resonant Inelastic X-ray scattering

    Czech Academy of Sciences Publication Activity Database

    Monney, C.; Bisogni, V.; Zhou, K.J.; Kraus, R.; Strocov, V.N.; Behr, G.; Málek, Jiří; Kuzian, R.; Drechsler, S.-L.; Johnston, S.; Revcolevschi, A.; Büchner, B.; Ronnow, H.M.; van den Brink, J.; Geck, J.; Schmitt, T.

    2013-01-01

    Roč. 110, č. 8 (2013), "087403-1"-"087403-5" ISSN 0031-9007 Institutional support: RVO:68378271 Keywords : RIXS * spin correlations * temperature dependence of Zhang-Rice singlet Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.728, year: 2013

  10. Quantum spin liquid and spin ice states in new pyrochlores

    Science.gov (United States)

    Sibille, Romain

    Magnetic systems with competing interactions can adopt exotic ground states. A particularly promising class is that of the geometrically frustrated magnets, such as the A2B2O7 pyrochlores, in which unusual spin liquids appear. Some of these phases feature short-range correlated states analogous to a Coulomb phase and give rise to emergent quasiparticle excitations. Although cases like the classical spin ice are reasonably well understood, the theoretical expectation is that quantum fluctuations lead to novel phases which are quantum spin liquids (QSLs). For instance, the quantum spin ice (QSI) is a generalization of the classical spin ice state to include quantum fluctuations, such that the effective theory becomes emergent quantum electrodynamics - the classical monopoles become coherent quantum quasiparticles, and a novel excitation playing the role of the photon appears. In this talk, I will present results on three novel materials with potential for QSL states. Each of them corresponds to a way to potentially strengthen the role of quantum fluctuations on the ground state properties of pyrochlore magnets. Firstly, I will demonstrate that, in Tb2Hf2O7, where a sizeable gap isolates the non-Kramers ground state doublet at low temperature, a large amount of anion Frenkel disorder leads to quenched random crystal fields and disordered magnetic interactions. The detailed study of this material demonstrates that disorder can play a crucial role in preventing long-range magnetic order at low temperatures, and instead induces a strongly-fluctuating Coulomb spin liquid with defect-induced frozen magnetic degrees of freedom. Secondly, I will present results on another QSL candidate based on non-Kramers ions, Pr2Hf2O7, which displays striking characteristics of the ferromagnetic correlations expected in a QSI. Finally, in the pyrochlore Ce2Sn2O7, where macroscopic measurements suggest an antiferromagnetic liquid ground state with quantum fluctuations, I will present

  11. Room-temperature antiferromagnetic memory resistor.

    Science.gov (United States)

    Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

    2014-04-01

    The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

  12. Landau model for the multiferroic delafossite antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J.L, E-mail: jlr@fisica.uminho.pt [Centro de Física da Universidade do Minho, 4710-057 Braga (Portugal); Perez-Mato, J.M [Dpto. de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apartado 644, 48080 Bilbao (Spain); Vieira, L.G [Centro de Física da Universidade do Minho, 4710-057 Braga (Portugal)

    2016-10-15

    A symmetry based framework is used to describe the complex phase diagrams observed in the multiferroic delafossite compounds. A free energy Landau functional is derived from the analysis of the transformation properties of the most general incommensurate magnetic spin order parameter. A principle of maximal symmetry is invoked and the stability of each of the different higher symmetry phases considered. The competition between different potential ground states is analysed within the scope of a simplified model, which emphasizes the role of the symmetry allowed phase dependent biquadratic couplings. The cross-over between the different competing states is also discussed. The results show that the diverse set of phase diagrams that are experimentally observed in this class of triangular lattice antiferromagnets and, in particular, the stabilization of magnetically induced ferroelectric states, can be well interpreted and described within this integrated phenomenological approximation. - Highlights: • Symmetry considerations are used to analyze the phase diagrams of the compounds. • The competition between possible ground states is discussed. • The field induced transitions between competing states are described.

  13. Perfusion imaging of brain gliomas using arterial spin labeling: correlation with histopathological vascular density in MRI-guided biopsies

    Energy Technology Data Exchange (ETDEWEB)

    Di, Ningning; Pang, Haopeng; Ren, Yan; Yao, Zhenwei; Feng, Xiaoyuan [Huashan Hospital Fudan University, Department of Radiology, Shanghai (China); Dang, Xuefei [Shang Hai Gamma Knife Hospital, Shanghai (China); Cheng, Wenna [Binzhou Medical University Affiliated Hospital, Department of Pharmacy, Binzhou (China); Wu, Jingsong; Yao, Chengjun [Huashan Hospital Fudan University, Department of Neurosurgery, Shanghai (China)

    2017-01-15

    This study was designed to determine if cerebral blood flow (CBF) derived from arterial spin labeling (ASL) perfusion imaging could be used to quantitatively evaluate the microvascular density (MVD) of brain gliomas on a ''point-to-point'' basis by matching CBF areas and surgical biopsy sites as accurate as possible. The study enrolled 47 patients with treatment-naive brain gliomas who underwent preoperative ASL, 3D T1-weighted imaging with gadolinium contrast enhancement (3D T1C+), and T2 fluid acquisition of inversion recovery (T2FLAIR) sequences before stereotactic surgery. We histologically quantified MVD from CD34-stained sections of stereotactic biopsies and co-registered biopsy locations with localized CBF measurements. The correlation between CBF and MVD was determined using Spearman's correlation coefficient. P ≤.05 was considered statistically significant. Of the 47 patients enrolled in the study, 6 were excluded from the analysis because of brain shift or poor co-registration and localization of the biopsy site during surgery. Finally, 84 biopsies from 41 subjects were included in the analysis. CBF showed a statistically significant positive correlation with MVD (ρ = 0.567; P =.029). ASL can be a useful noninvasive perfusion MR method for quantitative evaluation of the MVD of brain gliomas. (orig.)

  14. Perfusion imaging of brain gliomas using arterial spin labeling: correlation with histopathological vascular density in MRI-guided biopsies

    International Nuclear Information System (INIS)

    Di, Ningning; Pang, Haopeng; Ren, Yan; Yao, Zhenwei; Feng, Xiaoyuan; Dang, Xuefei; Cheng, Wenna; Wu, Jingsong; Yao, Chengjun

    2017-01-01

    This study was designed to determine if cerebral blood flow (CBF) derived from arterial spin labeling (ASL) perfusion imaging could be used to quantitatively evaluate the microvascular density (MVD) of brain gliomas on a ''point-to-point'' basis by matching CBF areas and surgical biopsy sites as accurate as possible. The study enrolled 47 patients with treatment-naive brain gliomas who underwent preoperative ASL, 3D T1-weighted imaging with gadolinium contrast enhancement (3D T1C+), and T2 fluid acquisition of inversion recovery (T2FLAIR) sequences before stereotactic surgery. We histologically quantified MVD from CD34-stained sections of stereotactic biopsies and co-registered biopsy locations with localized CBF measurements. The correlation between CBF and MVD was determined using Spearman's correlation coefficient. P ≤.05 was considered statistically significant. Of the 47 patients enrolled in the study, 6 were excluded from the analysis because of brain shift or poor co-registration and localization of the biopsy site during surgery. Finally, 84 biopsies from 41 subjects were included in the analysis. CBF showed a statistically significant positive correlation with MVD (ρ = 0.567; P =.029). ASL can be a useful noninvasive perfusion MR method for quantitative evaluation of the MVD of brain gliomas. (orig.)

  15. Dynamics of Coupled Quantum Spin Chains

    International Nuclear Information System (INIS)

    Schulz, H.J.

    1996-01-01

    Static and dynamical properties of weakly coupled antiferromagnetic spin chains are treated using a mean-field approximation for the interchain coupling and exact results for the resulting effective one-dimensional problem. Results for staggered magnetization, Nacute eel temperature, and spin wave excitations are in agreement with experiments on KCuF 3 . The existence of a narrow longitudinal mode is predicted. The results are in agreement with general scaling arguments, contrary to spin wave theory. copyright 1996 The American Physical Society

  16. A mean field study of the quasi-one-dimensional antiferromagnetic anisotropic Heisenberg model

    International Nuclear Information System (INIS)

    Benyoussef, A.

    1996-10-01

    The effect of the chain and the dimer anisotropies on the ground state energy and the energy gap of the spin-1/2 quasi-one-dimensional antiferromagnetic Heisenberg model is investigated using a mean field theory. The dependence of the magnetization and the effective hopping parameters on the anisotropy α xy (=J xy perpendicular /J xy parallel ) are presented for several values of the chain anisotropy. However, such a system exhibits a transition from antiferromagnetic ordered to disordered phases for arbitrary chain anisotropy and dimer anisotropy. (author). 22 refs, 11 figs

  17. Ground-state candidate for the classical dipolar kagome Ising antiferromagnet

    Science.gov (United States)

    Chioar, I. A.; Rougemaille, N.; Canals, B.

    2016-06-01

    We have investigated the low-temperature thermodynamic properties of the classical dipolar kagome Ising antiferromagnet using Monte Carlo simulations, in the quest for the ground-state manifold. In spite of the limitations of a single-spin-flip approach, we managed to identify certain ordering patterns in the low-temperature regime and we propose a candidate for this unknown state. This configuration presents some intriguing features and is fully compatible with the extrapolations of the at-equilibrium thermodynamic behavior sampled so far, making it a very likely choice for the dipolar long-range ordered state of the classical kagome Ising antiferromagnet.

  18. Spintronic materials and devices based on antiferromagnetic metals

    Directory of Open Access Journals (Sweden)

    Y.Y. Wang

    2017-04-01

    Full Text Available In this paper, we review our recent experimental developments on antiferromagnet (AFM spintronics mainly comprising Mn-based noncollinear AFM metals. IrMn-based tunnel junctions and Hall devices have been investigated to explore the manipulation of AFM moments by magnetic fields, ferromagnetic materials and electric fields. Room-temperature tunneling anisotropic magnetoresistance based on IrMn as well as FeMn has been successfully achieved, and electrical control of the AFM exchange spring is realized by adopting ionic liquid. In addition, promising spin-orbit effects in AFM as well as spin transfer via AFM spin waves reported by different groups have also been reviewed, indicating that the AFM can serve as an efficient spin current source. To explore the crucial role of AFM acting as efficient generators, transmitters, and detectors of spin currents is an emerging topic in the field of magnetism today. AFM metals are now ready to join the rapidly developing fields of basic and applied spintronics, enriching this area of solid-state physics and microelectronics.

  19. Metamagnetic phase transition of the antiferromagnetic Heisenberg icosahedron.

    Science.gov (United States)

    Schröder, Christian; Schmidt, Heinz-Jürgen; Schnack, Jürgen; Luban, Marshall

    2005-05-27

    The observation of hysteresis effects in single molecule magnets like Mn12-acetate has initiated ideas of future applications in storage technology. The appearance of a hysteresis loop in such compounds is an outcome of their magnetic anisotropy. In this Letter we report that magnetic hysteresis occurs in a spin system without any anisotropy, specifically where spins mounted on the vertices of an icosahedron are coupled by antiferromagnetic isotropic nearest-neighbor Heisenberg interaction giving rise to geometric frustration. At T = 0 this system undergoes a first-order metamagnetic phase transition at a critical field Bc between two distinct families of ground state configurations. The metastable phase of the system is characterized by a temperature and field dependent survival probability distribution.

  20. Magnetocaloric properties of a frustrated Blume-Capel antiferromagnet

    Directory of Open Access Journals (Sweden)

    Žukovič Milan

    2014-07-01

    Full Text Available Low-temperature magnetization processes and magnetocaloric properties of a geometrically frustrated spin-1 Blume-Capel model on a triangular lattice are studied by Monte Carlo simulations. The model is found to display qualitatively different behavior depending on the sign of the single-ion anisotropy D. For positive values of D we observe two magnetization plateaus, similar to the spin-1/2 Ising antiferromagnet, and negative isothermal entropy changes for any field intensity. For a range of small negative values of D there are four magnetization plateaus and the entropy changes can be either negative or positive, depending on the field. If D is negative but large in absolute value then the entropy changes are solely positive.

  1. Magnetic structure and interactions in the quasi-1D antiferromagnet CaV{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, Oliver; Lake, Bella [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Technische Universitaet Berlin, Institut fuer Festkoerperphysik, Berlin (Germany); Daoud-Aladine, Aziz [ISIS Facility, Rutherford Appleton Lab., Chilton (United Kingdom); Reehuis, Manfred [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Prokes, Karel; Klemke, Bastian; Kiefer, Klaus [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Yan, Jiaqiang; Niazi, Asad; Johnston, David C. [Ames Lab., Departement of Physics and Astronomy, Iowa State University, Ames (United States); Honecker, Andreas [Universitaet Goettingen, Institut fuer Theoretische Physik, Goettingen (Germany)

    2009-07-01

    CaV{sub 2}O{sub 4} is a spin-1 antiferromagnet where the magnetic vanadium ions are arranged on quasi-one-dimensional zig-zag chains with frustrated antiferromagnetic exchange interactions. Here we present high temperature susceptibility and single-crystal neutron diffraction measurements, which are used to deduce the magnetic structure, dominant exchange interactions and orbital configurations. The results suggest that at high temperatures of CaV{sub 2}O{sub 4}, the zig-zags behave as Haldane chains but at low temperatures, orbital ordering lifts the exchange frustration and the zig-zags become spin-1 ladders.

  2. Surface and step dynamics of a semi-infinite insulating antiferromagnet system

    CERN Document Server

    Tamine, M

    2003-01-01

    We have carried out a theoretical study of the localized spin-wave modes near the surface step of the insulating Heisenberg antiferromagnet. In this work, we study the full magnetic problem arising from the absence of translational symmetry due to the presence of a magnetic surface and step. The calculation concerns in particular the spin fluctuation dynamics and employs the matching procedure in the random-phase approximation. Only the nearest neighbours exchange interactions are considered between the spins in the model. The analytical formalism presented here determines the bulk and evanescent spin fluctuation fields in the two-dimensional plane normal to the surface and step regions. The results are used to calculate the localized modes of magnons associated with the step and surface terraces. The present model may be generalized to treat the spin fluctuations dynamics of other extended surface imperfections or nanostructures, provided they preserve the translation symmetry of the ordered spins along a di...

  3. Variational treatment of the Shastry-Sutherland antiferromagnet using Projected Entangled Pair States (PEPS)

    OpenAIRE

    Isacsson, A.; Syljuasen, O. F.

    2006-01-01

    We have applied a variational algorithm based on Projected Entangled Pair States (PEPS) to a two dimensional frustrated spin system, the spin-1/2 antiferromagnetic Heisenberg model on the Shastry-Sutherland lattice. We use the class of PEPS with internal tensor dimension D=2, the first step beyond product states (D=1 PEPS). We have found that the D=2 variational PEPS algorithm is able to capture the physics in both the valence-bond crystal and the Neel ordered state. Also the spin-textures gi...

  4. The importance of the on-site electron-electron interaction for the magnetic coupling in the zigzag spin-chain compound In2VO5

    KAUST Repository

    Wang, Hao

    2010-09-27

    We present first-principles electronic structure calculations for the zigzag spin-chain compound In2VO5 using the generalized gradient approximation both with and without inclusion of an on-site Coulomb interaction. It has been proposed that In2VO5 is characterized by itinerant V 3d electrons at high temperature and localized electrons at low temperature. Consequently, it is to be expected that electronic correlations play an important role for the magnetic transition from ferromagnetic to antiferromagnetic exchange around 120 K. In this context, we study the electronic and magnetic properties of a set of possible spin configurations. Our calculations show that inclusion of an on-site Coulomb interaction in fact changes the ground state from ferromagnetic to antiferromagnetic. © 2010 IOP Publishing Ltd.

  5. Singular ferromagnetic susceptibility of the transverse-field Ising antiferromagnet on the triangular lattice

    Science.gov (United States)

    Biswas, Sounak; Damle, Kedar

    2018-02-01

    A transverse magnetic field Γ is known to induce antiferromagnetic three-sublattice order of the Ising spins σz in the triangular lattice Ising antiferromagnet at low enough temperature. This low-temperature order is known to melt on heating in a two-step manner, with a power-law ordered intermediate temperature phase characterized by power-law correlations at the three-sublattice wave vector Q : ˜cos(Q .R ⃗) /|R⃗| η (T ) with the temperature-dependent power-law exponent η (T )∈(1 /9 ,1 /4 ) . Here, we use a quantum cluster algorithm to study the ferromagnetic easy-axis susceptibility χu(L ) of an L ×L sample in this power-law ordered phase. Our numerical results are consistent with a recent prediction of a singular L dependence χu(L ) ˜L2 -9 η when η (T ) is in the range (1 /9 ,2 /9 ) . This finite-size result implies, via standard scaling arguments, that the ferromagnetic susceptibility χu(B ) to a uniform field B along the easy axis is singular at intermediate temperatures in the small B limit, χu(B ) ˜|B| -4/-18 η 4 -9 η for η (T )∈(1 /9 ,2 /9 ) , although there is no ferromagnetic long-range order in the low temperature state. Additionally we establish similar two-step melting behavior (via a study of the order parameter susceptibility χQ) in the case of the ferrimagnetic three-sublattice ordered phase which is stabilized by ferromagnetic next-neighbor couplings (J2) and confirm that the ferromagnetic susceptibility obeys the predicted singular form in the associated power-law ordered phase.

  6. Antiferromagnetic Heisenberg model on the icosahedron: influence of connectivity and the transition from the classical to the quantum limit.

    Science.gov (United States)

    Konstantinidis, N P

    2015-02-25

    The antiferromagnetic Heisenberg model on the icosahedron presents unconventional properties at the classical and quantum level, which originate in the frustrated nature of the interactions between the spins. Here we examine the importance of the connectivity of the icosahedron for the appearance of a magnetization discontinuity as a function of an external field which separates two families of lowest energy configurations. We also investigate the transition from the classical to the quantum limit. The influence of connectivity on the magnetic properties is revealed by considering the cluster as being made up of a closed strip of a triangular lattice with two additional spins attached. The classical magnetization discontinuity is shown to evolve continuously from the discontinuity effected by these two spins when they are uncoupled to the cluster. In the second part the transition from the classical to the quantum limit is examined by focusing on the low energy spectrum, taking fully into account the spatial and the spin symmetry of the model in the characterization of the states. A symmetry analysis of the highly degenerate lowest energy classical manifold identifies as its direct fingerprint the low energy quantum states for spin magnitude as low as s = 1, with the latter following a tower of states behavior which relates to the icosahedron having a structure reminiscent of a depleted triangular lattice. The classical character of the AHM for small s is also detected on the ground state energy and correlation functions. On the other hand the classical magnetization discontinuity in a field eventually disappears for small s, after a weak reentrant behavior.

  7. Influence of growth conditions on exchange bias of NiMn-based spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Wienecke, Anja; Kruppe, Rahel; Rissing, Lutz [Institute for Microproduction Technology, Leibniz Universität Hannover, 30823 Garbsen (Germany)

    2015-05-07

    As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with high exchange bias are thermally more stable than samples with low exchange bias. Those structures promoting a high exchange bias are seemingly the same suppressing thermally induced diffusion processes (A. Wienecke and L. Rissing, “Relationship between thermal stability and layer-stack/structure of NiMn-based GMR systems,” in IEEE Transaction on Magnetic Conference (EMSA 2014)). Many investigations were carried out on the influence of the sputtering parameters as well as the layer thickness on the magnetoresistive effect. The influence of these parameters on the exchange bias and the sample's thermal stability, respectively, was hardly taken into account. The investigation described here concentrates on the last named issue. The focus lies on the influence of the sputtering parameters and layer thickness of the “starting layers” in the stack and the layers forming the (synthetic) antiferromagnet. This paper includes a guideline for the evaluated sputtering conditions and layer thicknesses to realize a high exchange bias and presumably good thermal stability for NiMn-based spin valves with a synthetic antiferromagnet.

  8. Quantum mechanics and the theories of local hidden variables: an experimental test by measuring the spin correlation function in p-p scattering

    International Nuclear Information System (INIS)

    Lamehi-Rachti, Mohammad.

    1976-01-01

    The Einstein-Podolsky-Rosen paradox is briefly exposed with the Bell theorem on hidden variables and the locality principle. The conditions for an ideal experiment are discussed and the results from γ-γ correlation experiments are given. The principle of an experimental measurement of the spin correlation function predicted by the quantum mechanics theory is derived, new hypotheses to be introduced are discussed. The formula giving the dependence of the counting asymmetry on the spin correlation function, polarimeter analyzing power, and geometric correlation is developed. The principle of a Monte Carlo calculation is also exposed. The experimental device is described with the methods for measuring the subsidiary quantities and experimental results are analyzed [fr

  9. Static and Dynamical Properties of Antiferromagnetic Skyrmions in the Presence of Applied Current and Temperature

    Science.gov (United States)

    Barker, Joseph; Tretiakov, Oleg A.

    2016-04-01

    Skyrmions are topologically protected entities in magnetic materials which have the potential to be used in spintronics for information storage and processing. However, Skyrmions in ferromagnets have some intrinsic difficulties which must be overcome to use them for spintronic applications, such as the inability to move straight along current. We show that Skyrmions can also be stabilized and manipulated in antiferromagnetic materials. An antiferromagnetic Skyrmion is a compound topological object with a similar but of opposite sign spin texture on each sublattice, which, e.g., results in a complete cancellation of the Magnus force. We find that the composite nature of antiferromagnetic Skyrmions gives rise to different dynamical behavior due to both an applied current and temperature effects.

  10. Scaling relations of three-dimensional random-exchange quantum antiferromagnets

    Science.gov (United States)

    Tan, Deng-Ruei; Jiang, Fu-Jiun

    2015-11-01

    The thermal and ground state properties of a class of three-dimensional (3D) random-exchange spin-1/2 antiferromagnets are studied using first principles quantum Monte Carlo method. Our motivation is to examine whether the newly discovered universal scaling properties, which connect the Néel temperature and the staggered magnetization density, for the clean 3D quantum dimerized Heisenberg models remain valid for the random-exchange models considered here. Remarkably, similar to the clean systems, our Monte Carlo results indicate that these scaling relations also emerge for the considered models with the introduced antiferromagnetic randomness. The scope of the validity of these scaling properties for the 3D quantum antiferromagnets is investigated as well.

  11. Spin thermoelectric effects in organic single-molecule devices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.L.; Wang, M.X.; Qian, C.; Hong, X.K.; Zhang, D.B.; Liu, Y.S.; Yang, X.F., E-mail: xfyang@cslg.edu.cn

    2017-05-25

    Highlights: • A stronger spin thermoelectric performance in a polyacetylene device is observed. • For the antiferromagnetic (AFM) ordering, a transport gap is opened. Thus the thermoelectric effects are largely enhanced. - Abstract: The spin thermoelectric performance of a polyacetylene chain bridging two zigzag graphene nanoribbons (ZGNRs) is investigated based on first principles method. Two different edge spin arrangements in ZGNRs are considered. For ferromagnetic (FM) ordering, transmission eigenstates with different spin indices distributed below and above Fermi level are observed, leading directly to a strong spin thermoelectric effect in a wide temperature range. With the edge spins arranged in the antiferromagnetic (AFM) ordering, an obvious transport gap appears in the system, which greatly enhances the thermoelectric effects. The presence of a small spin splitting also induces a spin thermoelectric effect greater than the charge thermoelectric effect in certain temperature range. In general, the single-molecule junction exhibits the potential to be used for the design of perfect thermospin devices.

  12. Arterial spin labeling in patients with chic cerebral artery steno-occlusive disease - Correlation with 15O-PET

    International Nuclear Information System (INIS)

    Kamano, Hironori; Yoshiura, Takashi; Hiwatashi, Akio; Abe, Koichiro; Yamashita, Koji; Honda, Hiroshi; Togao, Osamu

    2013-01-01

    Background: Heterogeneity of arterial transit time due to cerebral artery steno-occlusive lesions hampers accurate regional cerebral blood flow measurement by arterial spin labeling (ASL). Purpose: To assess the feasibility of regional cerebral blood flow measurement by ASL with multiple-delay time sampling in patients with steno-occlusive diseases by comparing with positron emission tomography (PET), and to determine whether regional arterial transit time measured by this ASL technique is correlated with regional mean transit time, a PET index of perfusion pressure. Material and Methods: Sixteen patients with steno-occlusive diseases received both ASL and 15 O-PET. The mean regional cerebral blood flow measured by ASL and PET, regional arterial transit time by ASL, and regional mean transit time by PET were obtained by a region-of-interest analysis. Correlation between regional cerebral blood flow by ASL and that by PET, and correlation between regional arterial transit time by ASL and regional mean transit time by PET were tested using Pearson's correlation coefficient for both absolute and relative values. A multivariate regression analysis was performed to test whether regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling the effect of regional cerebral blood flow by ASL. Results: A significant positive correlation was found between regional cerebral blood flow by ASL and that by PET for both absolute (r = 0.520, P < 0.0001) and relative (r = 0.691, P < 0.0001) values. A significant positive correlation was found between regional arterial transit time by ASL and regional mean transit time by PET both for absolute (r = 0.369, P = 0.0002) and relative (r = 0.443, P < 0.0001) values. The regression analysis revealed that regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling regional cerebral blood flow by ASL

  13. Simultaneous optimization of spin fluctuations and superconductivity under pressure in an iron-based superconductor.

    Science.gov (United States)

    Ji, G F; Zhang, J S; Ma, Long; Fan, P; Wang, P S; Dai, J; Tan, G T; Song, Y; Zhang, C L; Dai, Pengcheng; Normand, B; Yu, Weiqiang

    2013-09-06

    We present a high-pressure NMR study of the overdoped iron pnictide superconductor NaFe0.94Co0.06As. The low-energy antiferromagnetic spin fluctuations in the normal state, manifest as the Curie-Weiss upturn in the spin-lattice relaxation rate 1/(75)T1T, first increase strongly with pressure but fall again at P>Popt=2.2  GPa. Neither long-ranged magnetic order nor a structural phase transition is encountered up to 2.5 GPa. The superconducting transition temperature Tc shows a pressure dependence identical to the spin fluctuations. Our observations demonstrate that magnetic correlations and superconductivity are optimized simultaneously as a function of the electronic structure, thereby supporting very strongly a magnetic origin of superconductivity.

  14. Coherent Two-Dimensional Terahertz Magnetic Resonance Spectroscopy of Collective Spin Waves.

    Science.gov (United States)

    Lu, Jian; Li, Xian; Hwang, Harold Y; Ofori-Okai, Benjamin K; Kurihara, Takayuki; Suemoto, Tohru; Nelson, Keith A

    2017-05-19

    We report a demonstration of two-dimensional (2D) terahertz (THz) magnetic resonance spectroscopy using the magnetic fields of two time-delayed THz pulses. We apply the methodology to directly reveal the nonlinear responses of collective spin waves (magnons) in a canted antiferromagnetic crystal. The 2D THz spectra show all of the third-order nonlinear magnon signals including magnon spin echoes, and 2-quantum signals that reveal pairwise correlations between magnons at the Brillouin zone center. We also observe second-order nonlinear magnon signals showing resonance-enhanced second-harmonic and difference-frequency generation. Numerical simulations of the spin dynamics reproduce all of the spectral features in excellent agreement with the experimental 2D THz spectra.

  15. Magnetism, spin-lattice-orbital coupling and exchange-correlation energy in oxide heterostructures: Nickelate, titanate, and ruthenate

    Science.gov (United States)

    Han, Myung-Joon

    Many interesting physical phenomena and material characteristics in transition-metal oxides (TMO) come out of the intriguing interplay between charge, spin, orbital, and lattice degrees of freedom. In the thin film and/or heterointerface form of TMO, this feature can be controlled and thus be utilized. Simultaneously, however, its detailed characteristic is more difficult to be identified experimentally. For this reason, the first-principles-based approach has been playing an important role in this field of research. In this talk, I will try to give an overview of current status of first-principles methodologies especially for the magnetism in the correlated oxide heterostructures or thin films. Nickelate, titanate, and ruthenate will be taken as representative examples to demonstrate the powerfulness of and the challenges to the current methodologies On the one hand, first-principles calculation provides the useful information, understanding and prediction which can hardly be obtained from other theoretical and experimental techniques. Nickelate-manganite superlattices (LaNiO3/LaMnO3 and LaNiO3/CaMnO3) are taken as examples. In this interface, the charge transfer can induce the ferromagnetism and it can be controlled by changing the stacking sequence and number of layers. The exchange-correlation (XC) functional dependence seems to give only quantitatively different answers in this case. On the other hand, for the other issues such as orbital polarization/order coupled with spin order, the limitation of current methodology can be critical. This point will be discussed with the case of tatinate superlattice (LaTiO3/LaAlO3) . For ruthenates (SrRuO3\\ and Sr2RuO4) , we found that the probably more fundamental issue could be involved. The unusually strong dependence on the XC functional parametrization is found to give a qualitatively different conclusion for the experimentally relevant parameter regions. This work was supported by National Research Foundation of

  16. Spin-Orbital Correlated Dynamics in the Spinel-Type Vanadium Oxide MnV2 O4

    Science.gov (United States)

    Matsuura, Keisuke; Sagayama, Hajime; Uehara, Amane; Nii, Yoichi; Kajimoto, Ryoichi; Kamazawa, Kazuya; Ikeuchi, Kazuhiko; Ji, Sungdae; Abe, Nobuyuki; Arima, Taka-hisa

    2017-07-01

    We investigate the magnetic dynamics in the spinel-type vanadium oxide MnV2 O4 . Inelastic neutron scattering around 10 meV and a Heisenberg model analysis have revealed that V3 + spin-wave modes exist at a lower-energy region than previously reported. The scattering around 20 meV cannot be reproduced with the spin-wave analysis. We propose that this scattering could originate from the spin-orbital coupled excitation. This scattering is most likely attributable to V3 + spin-wave modes, entangled with the orbital hybridization between t2 g orbitals.

  17. Unconventional spin order in the triangular lattice system NaCrO2: A neutron scattering study

    International Nuclear Information System (INIS)

    Hsieh, D.; Qian, D.; Berger, R.F.; Cava, R.J.; Lynn, J.W.; Huang, Q.; Hasan, M.Z.

    2008-01-01

    We report high resolution neutron scattering measurements on the rhombohedrally stacked triangular antiferromagnet NaCrO 2 which has recently been shown to exhibit an unusually broad fluctuating cross-over regime extending far below the onset of spin freezing at T c . Our results show that at T c purely two-dimensional quasi-static spin correlations of the 120 o type exist. Below some cross-over temperature (T∼0.75T c ) a small incommensuration develops which helps resolve the inter-layer spin frustration and drives short-range three-dimensional magnetic order. This incommensuration assisted dimensional cross-over suggests that inter-layer frustration is responsible for stabilizing the rare 2D correlated phase above 0.75T c

  18. NMR Studies of the Vanadium Spin Dynamics and Spin Structure in LiV2O4, CaV2O4, and (LixV1-x)3BO5 (x is almost equal to 0.33, 0.40)

    International Nuclear Information System (INIS)

    Xiaopeng Zong

    2007-01-01

    Strong electron correlation is believed to be an essential and unifying factor in diverse properties of condensed matter systems. Ground states that can arise due to electron correlation effects include Mott insulators, heavy fermion, ferromagnetism and antiferromagnetism, spin glasses, and high-temperature superconductivity. The electronic systems in transition metal oxide compounds are often highly correlated. In this thesis, the author presents experimental studies on three strongly correlated vanadium oxide compounds: LiV 2 O 4 , (Li x V 1-x ) 3 BO 5 , and CaV 2 O 4 , which have completely different ground states

  19. Spin-charge separation in the t-J model: Magnetic and transport anomalies

    International Nuclear Information System (INIS)

    Weng, Z.Y.; Sheng, D.N.; Ting, C.S.

    1995-01-01

    A real spin-charge separation scheme is found based on a saddle-point state of the t-J model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at finite doping so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic residual couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at (π/a,π/a) with a doping-dependent width. This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exists a characteristic temperature scale below thich a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a finite energy regime. In the transport, a strong-range phase intereference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-T resistivity and a T 2 Hall angle. We discuss the striking similarities of these theoretical features with those found in the high-T c cuprates and give a consistent picture for the latter. Electronic properties like Fermi surface and superconducting pairing in this framework are also discussed

  20. Spin fluctuations and the

    Directory of Open Access Journals (Sweden)

    V.M. Loktev

    2008-09-01

    Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

  1. Cross-Correlated Relaxation of Dipolar Coupling and Chemical-Shift Anisotropy in Magic-Angle Spinning R1ρ NMR Measurements: Application to Protein Backbone Dynamics Measurements

    Science.gov (United States)

    Kurauskas, Vilius; Weber, Emmanuelle; Hessel, Audrey; Ayala, Isabel; Marion, Dominique; Schanda, Paul

    2016-01-01

    Transverse relaxation rate measurements in MAS solid-state NMR provide information about molecular motions occurring on nanoseconds-to-milliseconds (ns-ms) time scales. The measurement of heteronuclear (13C, 15N) relaxation rate constants in the presence of a spin-lock radio-frequency field (R1ρ relaxation) provides access to such motions, and an increasing number of studies involving R1ρ relaxation in proteins has been reported. However, two factors that influence the observed relaxation rate constants have so far been neglected, namely (i) the role of CSA/dipolar cross-correlated relaxation (CCR), and (ii) the impact of fast proton spin flips (i.e. proton spin diffusion and relaxation). We show that CSA/D CCR in R1ρ experiments is measurable, and that this cross-correlated relaxation rate constant depends on ns-ms motions, and can thus itself provide insight into dynamics. We find that proton spin-diffusion attenuates this cross-correlated relaxation, due to its decoupling effect on the doublet components. For measurements of dynamics, the use of R1ρ rate constants has practical advantages over the use of CCR rates, and the present manuscript reveals factors that have so far been disregarded and which are important for accurate measurements and interpretation. PMID:27500976

  2. Studies of a Large Odd-Numbered Odd-Electron Metal Ring: Inelastic Neutron Scattering and Muon Spin Relaxation Spectroscopy of Cr8 Mn.

    Science.gov (United States)

    Baker, Michael L; Lancaster, Tom; Chiesa, Alessandro; Amoretti, Giuseppe; Baker, Peter J; Barker, Claire; Blundell, Stephen J; Carretta, Stefano; Collison, David; Güdel, Hans U; Guidi, Tatiana; McInnes, Eric J L; Möller, Johannes S; Mutka, Hannu; Ollivier, Jacques; Pratt, Francis L; Santini, Paolo; Tuna, Floriana; Tregenna-Piggott, Philip L W; Vitorica-Yrezabal, Iñigo J; Timco, Grigore A; Winpenny, Richard E P

    2016-01-26

    The spin dynamics of Cr8 Mn, a nine-membered antiferromagnetic (AF) molecular nanomagnet, are investigated. Cr8 Mn is a rare example of a large odd-membered AF ring, and has an odd-number of 3d-electrons present. Odd-membered AF rings are unusual and of interest due to the presence of competing exchange interactions that result in frustrated-spin ground states. The chemical synthesis and structures of two Cr8 Mn variants that differ only in their crystal packing are reported. Evidence of spin frustration is investigated by inelastic neutron scattering (INS) and muon spin relaxation spectroscopy (μSR). From INS studies we accurately determine an appropriate microscopic spin Hamiltonian and we show that μSR is sensitive to the ground-spin-state crossing from S=1/2 to S=3/2 in Cr8 Mn. The estimated width of the muon asymmetry resonance is consistent with the presence of an avoided crossing. The investigation of the internal spin structure of the ground state, through the analysis of spin-pair correlations and scalar-spin chirality, shows a non-collinear spin structure that fluctuates between non-planar states of opposite chiralities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Breakdown of antiferromagnet order in polycrystalline NiFe/NiO bilayers probed with acoustic emission

    Science.gov (United States)

    Lebyodkin, M. A.; Lebedkina, T. A.; Shashkov, I. V.; Gornakov, V. S.

    2017-07-01

    Magnetization reversal of polycrystalline NiFe/NiO bilayers was investigated using magneto-optical indicator film imaging and acoustic emission techniques. Sporadic acoustic signals were detected in a constant magnetic field after the magnetization reversal. It is suggested that they are related to elastic waves excited by sharp shocks in the NiO layer with strong magnetostriction. Their probability depends on the history and number of repetitions of the field cycling, thus testifying the thermal-activation nature of the long-time relaxation of an antiferromagnetic order. These results provide evidence of spontaneous thermally activated switching of the antiferromagnetic order in NiO grains during magnetization reversal in ferromagnet/antiferromagnet (FM/AFM) heterostructures. The respective deformation modes are discussed in terms of the thermal fluctuation aftereffect in the Fulcomer and Charap model which predicts that irreversible breakdown of the original spin orientation can take place in some antiferromagnetic grains with disordered anisotropy axes during magnetization reversal of exchange-coupled FM/AFM structures. The spin reorientation in the saturated state may induce abrupt distortion of isolated metastable grains because of the NiO magnetostriction, leading to excitation of shock waves and formation of plate (or Lamb) waves.

  4. GPU-Accelerated Population Annealing Algorithm: Frustrated Ising Antiferromagnet on the Stacked Triangular Lattice

    Directory of Open Access Journals (Sweden)

    Borovský Michal

    2016-01-01

    Full Text Available The population annealing algorithm is a novel approach to study systems with rough free-energy landscapes, such as spin glasses. It combines the power of simulated annealing, Boltzmann weighted differential reproduction and sequential Monte Carlo process to bring the population of replicas to the equilibrium even in the low-temperature region. Moreover, it provides a very good estimate of the free energy. The fact that population annealing algorithm is performed over a large number of replicas with many spin updates, makes it a good candidate for massive parallelism. We chose the GPU programming using a CUDA implementation to create a highly optimized simulation. It has been previously shown for the frustrated Ising antiferromagnet on the stacked triangular lattice with a ferromagnetic interlayer coupling, that standard Markov Chain Monte Carlo simulations fail to equilibrate at low temperatures due to the effect of kinetic freezing of the ferromagnetically ordered chains. We applied the population annealing to study the case with the isotropic intra- and interlayer antiferromagnetic coupling (J2/|J1| = −1. The reached ground states correspond to non-magnetic degenerate states, where chains are antiferromagnetically ordered, but there is no long-range ordering between them, which is analogical with Wannier phase of the 2D triangular Ising antiferromagnet.

  5. Measurement of spin correlation between top and antitop quarks produced in $p\\bar{p}$ collisions at $\\sqrt{s} = 1.96$ TeV

    CERN Document Server

    Abazov, Victor Mukhamedovich; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Agnew, James P; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Askew, Andrew Warren; Atkins, Scott; Augsten, Kamil; Aushev, Volodymyr; Aushev, Yegor; Avila, Carlos A; Badaud, Frederique; Bagby, Linda F; Baldin, Boris; Bandurin, Dmitry V; Banerjee, Sunanda; Barberis, Emanuela; Baringer, Philip S; Bartlett, JFrederick; Bassler, Ursula Rita; Bazterra, Victor; Bean, Alice L; Begalli, Marcia; Bellantoni, Leo; Beri, Suman B; Bernardi, Gregorio; Bernhard, Ralf Patrick; Bertram, Iain A; Besancon, Marc; Beuselinck, Raymond; Bhat, Pushpalatha C; Bhatia, Sudeep; Bhatnagar, Vipin; Blazey, Gerald Charles; Blessing, Susan K; Bloom, Kenneth A; Boehnlein, Amber S; Boline, Daniel Dooley; Boos, Edward E; Borissov, Guennadi; Borysova, Maryna; Brandt, Andrew; Brandt, Oleg; Brock, Raymond L; Bross, Alan D; Brown, Duncan Paul; Bu, Xue-Bing; Buehler, Marc; Buescher, Volker; Bunichev, Viacheslav Yevgenyevich; Burdin, Sergey; Buszello, Claus Peter; Camacho-Perez, Enrique; Casey, Brendan Cameron Kieran; Castilla-Valdez, Heriberto; Caughron, Seth Aaron; Chakrabarti, Subhendu; Chan, Kwok Ming Leo; Chandra, Avdhesh; Chapon, Emilien; Chen, Guo; Cho, Sung-Woong; Choi, Suyong; Choudhary, Brajesh C; Cihangir, Selcuk; Claes, Daniel R; Clutter, Justace Randall; Cooke, Michael P; Cooper, William Edward; Corcoran, Marjorie D; Couderc, Fabrice; Cousinou, Marie-Claude; Cuth, Jakub; Cutts, David; Das, Amitabha; Davies, Gavin John; de Jong, Sijbrand Jan; De La Cruz-Burelo, Eduard; Deliot, Frederic; Demina, Regina; Denisov, Dmitri S; Denisov, Sergei P; Desai, Satish Vijay; Deterre, Cecile; DeVaughan, Kayle Otis; Diehl, HThomas; Diesburg, Michael; Ding, Pengfei; Dominguez, DAaron M; Dubey, Abhinav Kumar; Dudko, Lev V; Duperrin, Arnaud; Dutt, Suneel; Eads, Michael T; Edmunds, Daniel L; Ellison, John A; Elvira, VDaniel; Enari, Yuji; Evans, Harold G; Evdokimov, Anatoly V; Evdokimov, Valeri N; Faure, Alexandre; Feng, Lei; Ferbel, Thomas; Fiedler, Frank; Filthaut, Frank; Fisher, Wade Cameron; Fisk, HEugene; Fortner, Michael R; Fox, Harald; Franc, Jiri; Fuess, Stuart C; Garbincius, Peter H; Garcia-Bellido, Aran; Garcia-Gonzalez, Jose Andres; Gavrilov, Vladimir B; Geng, Weigang; Gerber, Cecilia Elena; Gershtein, Yuri S; Ginther, George E; Gogota, Olga; Golovanov, Georgy Anatolievich; Grannis, Paul D; Greder, Sebastien; Greenlee, Herbert B; Grenier, Gerald Jean; Gris, Phillipe Luc; Grivaz, Jean-Francois; Grohsjean, Alexander; Gruenendahl, Stefan; Gruenewald, Martin Werner; Guillemin, Thibault; Gutierrez, Gaston R; Gutierrez, Phillip; Haley, Joseph Glenn Biddle; Han, Liang; Harder, Kristian; Harel, Amnon; Hauptman, John Michael; Hays, Jonathan M; Head, Tim; Hebbeker, Thomas; Hedin, David R; Hegab, Hatim; Heinson, Ann; Heintz, Ulrich; Hensel, Carsten; Heredia-De La Cruz, Ivan; Herner, Kenneth Richard; Hesketh, Gavin G; Hildreth, Michael D; Hirosky, Robert James; Hoang, Trang; Hobbs, John D; Hoeneisen, Bruce; Hogan, Julie; Hohlfeld, Mark; Holzbauer, Jenny Lyn; Howley, Ian James; Hubacek, Zdenek; Hynek, Vlastislav; Iashvili, Ia; Ilchenko, Yuriy; Illingworth, Robert A; Ito, Albert S; Jabeen, Shabnam; Jaffre, Michel J; Jayasinghe, Ayesh; Jeong, Min-Soo; Jesik, Richard L; Jiang, Peng; Johns, Kenneth Arthur; Johnson, Emily; Johnson, Marvin E; Jonckheere, Alan M; Jonsson, Per Martin; Joshi, Jyoti; Jung, Andreas Werner; Juste, Aurelio; Kajfasz, Eric; Karacheban, Olena; Karmanov, Dmitriy Y; Katsanos, Ioannis; Kaur, Manbir; Kehoe, Robert Leo Patrick; Kermiche, Smain; Khalatyan, Norayr; Khanov, Alexander; Kharchilava, Avto; Kharzheev, Yuri N; Kiselevich, Ivan Lvovich; Kohli, Jatinder M; Kozelov, Alexander V; Kraus, James Alexander; Kumar, Ashish; Kupco, Alexander; Kurca, Tibor; Kuzmin, Valentin Alexandrovich; Lammers, Sabine Wedam; Lebrun, Patrice; Lee, Hyeon-Seung; Lee, Seh-Wook; Lee, William M; Lei, Xiaowen; Lellouch, Jeremie; Li, Dikai; Li, Hengne; Li, Liang; Li, Qi-Zhong; Lim, Jeong Ku; Lincoln, Donald W; Linnemann, James Thomas; Lipaev, Vladimir V; Lipton, Ronald J; Liu, Huanzhao; Liu, Yanwen; Lobodenko, Alexandre; Lokajicek, Milos; Lopes de Sa, Rafael; Luna-Garcia, Rene; Lyon, Adam Leonard; Maciel, Arthur KA; Madar, Romain; Magana-Villalba, Ricardo; Malik, Sudhir; Malyshev, Vladimir L; Mansour, Jason; Martinez-Ortega, Jorge; McCarthy, Robert L; Mcgivern, Carrie Lynne; Meijer, Melvin M; Melnitchouk, Alexander S; Menezes, Diego D; Mercadante, Pedro Galli; Merkin, Mikhail M; Meyer, Arnd; Meyer, Jorg Manfred; Miconi, Florian; Mondal, Naba K; Mulhearn, Michael James; Nagy, Elemer; Narain, Meenakshi; Nayyar, Ruchika; Neal, Homer A; Negret, Juan Pablo; Neustroev, Petr V; Nguyen, Huong Thi; Nunnemann, Thomas P; Hernandez Orduna, Jose de Jesus; Osman, Nicolas Ahmed; Osta, Jyotsna; Pal, Arnab; Parashar, Neeti; Parihar, Vivek; Park, Sung Keun; Partridge, Richard A; Parua, Nirmalya; Patwa, Abid; Penning, Bjoern; Perfilov, Maxim Anatolyevich; Peters, Reinhild Yvonne Fatima; Petridis, Konstantinos; Petrillo, Gianluca; Petroff, Pierre; Pleier, Marc-Andre; Podstavkov, Vladimir M; Popov, Alexey V; Prewitt, Michelle; Price, Darren; Prokopenko, Nikolay N; Qian, Jianming; Quadt, Arnulf; Quinn, Gene Breese; Ratoff, Peter N; Razumov, Ivan A; Ripp-Baudot, Isabelle; Rizatdinova, Flera; Rominsky, Mandy Kathleen; Ross, Anthony; Royon, Christophe; Rubinov, Paul Michael; Ruchti, Randal C; Sajot, Gerard; Sanchez-Hernandez, Alberto; Sanders, Michiel P; Santos, Angelo Souza; Savage, David G; Savitskyi, Mykola; Sawyer, HLee; Scanlon, Timothy P; Schamberger, RDean; Scheglov, Yury A; Schellman, Heidi M; Schott, Matthias; Schwanenberger, Christian; Schwienhorst, Reinhard H; Sekaric, Jadranka; Severini, Horst; Shabalina, Elizaveta K; Shary, Viacheslav V; Shaw, Savanna; Shchukin, Andrey A; Simak, Vladislav J; Skubic, Patrick Louis; Slattery, Paul F; Smirnov, Dmitri V; Snow, Gregory R; Snow, Joel Mark; Snyder, Scott Stuart; Soldner-Rembold, Stefan; Sonnenschein, Lars; Soustruznik, Karel; Stark, Jan; Stefaniuk, Nazar; Stoyanova, Dina A; Strauss, Michael G; Suter, Louise; Svoisky, Peter V; Titov, Maxim; Tokmenin, Valeriy V; Tsai, Yun-Tse; Tsybychev, Dmitri; Tuchming, Boris; Tully, Christopher George T; Uvarov, Lev; Uvarov, Sergey L; Uzunyan, Sergey A; Van Kooten, Richard J; van Leeuwen, Willem M; Varelas, Nikos; Varnes, Erich W; Vasilyev, Igor A; Verkheev, Alexander Yurievich; Vertogradov, Leonid S; Verzocchi, Marco; Vesterinen, Mika; Vilanova, Didier; Vokac, Petr; Wahl, Horst D; Wang, Michael HLS; Warchol, Jadwiga; Watts, Gordon Thomas; Wayne, Mitchell R; Weichert, Jonas; Welty-Rieger, Leah Christine; Williams, Mark Richard James; Wilson, Graham Wallace; Wobisch, Markus; Wood, Darien Robert; Wyatt, Terence R; Xie, Yunhe; Yamada, Ryuji; Yang, Siqi; Yasuda, Takahiro; Yatsunenko, Yuriy A; Ye, Wanyu; Ye, Zhenyu; Yin, Hang; Yip, Kin; Youn, Sungwoo; Yu, Jiaming; Zennamo, Joseph; Zhao, Tianqi Gilbert; Zhou, Bing; Zhu, Junjie; Zielinski, Marek; Zieminska, Daria; Zivkovic, Lidija

    2016-06-10

    We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \\pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.

  6. One dimensionalization in the spin-1 Heisenberg model on the anisotropic triangular lattice

    Science.gov (United States)

    Gonzalez, M. G.; Ghioldi, E. A.; Gazza, C. J.; Manuel, L. O.; Trumper, A. E.

    2017-11-01

    We investigate the effect of dimensional crossover in the ground state of the antiferromagnetic spin-1 Heisenberg model on the anisotropic triangular lattice that interpolates between the regime of weakly coupled Haldane chains (J'≪J ) and the isotropic triangular lattice (J'=J ). We use the density-matrix renormalization group (DMRG) and Schwinger boson theory performed at the Gaussian correction level above the saddle-point solution. Our DMRG results show an abrupt transition between decoupled spin chains and the spirally ordered regime at (J'/J) c˜0.42 , signaled by the sudden closing of the spin gap. Coming from the magnetically ordered side, the computation of the spin stiffness within Schwinger boson theory predicts the instability of the spiral magnetic order toward a magnetically disordered phase with one-dimensional features at (J'/J) c˜0.43 . The agreement of these complementary methods, along with the strong difference found between the intra- and the interchain DMRG short spin-spin correlations for sufficiently large values of the interchain coupling, suggests that the interplay between the quantum fluctuations and the dimensional crossover effects gives rise to the one-dimensionalization phenomenon in this frustrated spin-1 Hamiltonian.

  7. Neutron-scattering study of the spin-state transition and magnetic correlations in La1-xSrxCoO3 (x=0 and 0.08)

    International Nuclear Information System (INIS)

    Asai, K.; Yokokura, O.; Nishimori, N.; Chou, H.; Tranquada, J.M.; Shirane, G.; Higuchi, S.; Okajima, Y.; Kohn, K.

    1994-01-01

    LaCoO 3 exhibits two magnetic-electronic transitions, one near 90 K and a second near 500 K. A previous study of the paramagnetic scattering using polarized neutrons demonstrated that the low-temperature transition is associated with the thermal excitation of Co 3+ ions from the low-spin to the high-spin state. In the present work, we extend the paramagnetic-scattering measurements up to a temperature of 700 K. We find that the magnetic-scattering intensity decreases monotonically for temperatures above 300 K, indicating that the high-temperature transition is not dominantly magnetic in origin. Furthermore, the anomalous thermal expansion associated with the low-temperature transition is measured and shown to be consistent with a simple theoretical model for the spin-state transition. For comparison, paramagnetic-scattering measurements for La 0.92 Sr 0.08 CoO 3 are also presented. In this material the ferromagnetic correlations are substantially stronger than in the undoped compound, and no transition to the low-spin state is observed. Instead, the paramagnetic scattering increases steadily with decreasing temperature until saturating below 24 K, the same temperature at which the magnetization of the zero-field-cooled specimen shows a sharp cusp. These results suggest that the magnetic moments in the doped compound freeze into a spin-glass state at low temperature

  8. Antiferromagnetic CsCrF5 and canted antiferromagnetism in RbCrF5 and KCrF5

    Science.gov (United States)

    Jagličić, Zvonko; Mazej, Zoran

    2017-07-01

    In ACrF5 (A = Cs, Rb, K), Cr(IV) ions are coordinated by six fluoride ligands where the resulting CrF6 octahedra share cis vertexes to form infinite chains of ([CrIVF5]-)n. The geometry of the latter in Cs compound differs from that in K and Rb compounds. The results of investigations of the magnetic behaviour of these compounds have shown that an antiferromagnetic superexchange interaction is present within the chains with JCs = -10.2 cm-1, JRb = -13.3 cm-1, and JK = -13.1 cm-1. Additional ferromagnetic-like long-range ordering has been observed in KCrF5 and RbCrF5 below 6 K which can be explained, in a correlation with their crystal structures, as canted antiferromagnetism.

  9. Breatherlike electromagnetic wave propagation in an antiferromagnetic medium with Dzyaloshinsky-Moriya interaction

    International Nuclear Information System (INIS)

    Kavitha, L.; Saravanan, M.; Srividya, B.; Gopi, D.

    2011-01-01

    We investigate the nature of propagation of electromagnetic waves (EMWs) in an antiferromagnetic medium with Dzyaloshinsky-Moriya (DM) interaction environment. The interplay of bilinear and DM exchange spin coupling with the magnetic field component of the EMW has been studied by solving Maxwell's equations coupled with a nonlinear spin equation for the magnetization of the medium. We made a nonuniform expansion of the magnetization and magnetic field along the direction of propagation of EMW, in the framework of reductive perturbation method, and the dynamics of the system is found to be governed by a generalized derivative nonlinear Schroedinger (DNLS) equation. We employ the Jacobi-elliptic function method to solve the DNLS equation, and the electromagnetic wave propagation in an antiferromagnetic medium is governed by the breatherlike spatially and temporally coherent localized modes under the influence of DM interaction parameter.

  10. Spin texture motion in antiferromagnetic and ferromagnetic nanowires

    Czech Academy of Sciences Publication Activity Database

    Rodrigues, D.R.; Everschor-Sitte, K.; Tretiakov, O.A.; Sinova, Jairo; Abanov, A.

    2017-01-01

    Roč. 95, č. 17 (2017), s. 1-7, č. článku 174408. ISSN 2469-9950 R&D Projects: GA ČR GB14-37427G EU Projects: European Commission(XE) 610115 - SC2 Institutional support: RVO:68378271 Keywords : orbit torques * magnetization * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  11. Spinon confinement in the quasi-1D Ising-like antiferromagnet SrCo{sub 2}V{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe; Schmidt, Michael; Loidl, Alois; Deisenhofer, Joachim [Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg (Germany); Bera, Anup Kumar [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Lake, Bella [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Berlin (Germany)

    2015-07-01

    Using THz transmission spectroscopy in magnetic field, we have investigated low-energy magnetic excitations in the quasi-one-dimensional Ising-like XXZ antiferromagnet SrCo{sub 2}V{sub 2}O{sub 8}. Spinon-pair excitations on the antiferromagnetic ground state have been observed in the XXZ antiferromagnet. Spinon-pair bound states with entangled spin-orbit moment S = 1 are determined unambiguously. The hierarchy of the spinon-pair boundstates can be described by a one-dimensional Schroedinger equation with a linear confinement potential imposed by the interchain interaction.

  12. Collective spin excitations in the singlet-correlated band model: a comparison with resonant inelastic x-ray scattering

    International Nuclear Information System (INIS)

    Eremin, M V; Shigapov, I M; Thuy, Ho Thi Duyen

    2013-01-01

    We analyse the spin excitations near the optimal doping of superconducting layered cuprates taking into account both the local and the itinerant spin components self-consistently. The obtained expression allows us to reproduce well the basic features of the resonant inelastic x-ray scattering and neutron scattering data experiments using a reasonable set of tight-binding parameters corresponding to the angle-resolved photoemission spectroscopy data. We also find that the spin excitation branch along the (0,0) − (0,π) symmetry direction in the first Brillouin zone shows a splitting at T c . Possible experiments for verification of that prediction are briefly discussed. (paper)

  13. Magnetic hysteresis and domain wall dynamics in single chain magnets with antiferromagnetic interchain coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bukharov, A A; Ovchinnikov, A S; Baranov, N V [Department of Physics, Ural State University, Ekaterinburg, 620083 (Russian Federation); Inoue, K [Institute for Advanced Materials Research, Hiroshima University, Hiroshima (Japan)

    2010-11-03

    Using Monte Carlo simulations we investigate magnetic hysteresis in two- and three-dimensional systems of weakly antiferromagnetically coupled spin chains based on a scenario of domain wall (kink) motion within the chains. By adapting the model of walkers to simulate the domain wall dynamics and using the Ising-like dipole-dipole model, we study the effects of interchain coupling, temperature and anisotropy axis direction on hysteresis curves.

  14. Photo-induced antiferromagnetic interlayer coupling in Fe superlattices with iron silicide spacers

    Energy Technology Data Exchange (ETDEWEB)

    Mattson, J.E.; Fullerton, E.E.; Kumar, S.; Lee, S.R.; Sowers, C.H.; Grimsditch, M.; Bader, S.D. [Argonne National Lab., IL (United States); Parker, F.T. [California Univ., San Diego, La Jolla, CA (United States). Center for Magnetic Recording Research

    1993-09-01

    Sputtered Fe/FeSi films possessing antiferromagnetic (AF) interlayer coupling at room temperature develop ferromagnetic remanence when cooled below 100K, but the AF coupling can be restored at low temperature by exposure to visible light of sufficient intensity (>10 mW/mm{sup 2}). We attribute these effects to charge carriers in the FeSi spacer layer which, when thermally or photo-generated, are capable of communicating spin information between the Fe layers.

  15. Remanent Magnetization: Signature of Many-Body Localization in Quantum Antiferromagnets

    Science.gov (United States)

    Ros, V.; Müller, M.

    2017-06-01

    We study the remanent magnetization in antiferromagnetic, many-body localized quantum spin chains, initialized in a fully magnetized state. Its long time limit is an order parameter for the localization transition, which is readily accessible by standard experimental probes in magnets. We analytically calculate its value in the strong-disorder regime exploiting the explicit construction of quasilocal conserved quantities of the localized phase. We discuss analogies in cold atomic systems.

  16. Magnetotransport and Antiferromagnetic Behavior in ErP Epitaxial Layers on GaInP(001)

    Science.gov (United States)

    Nakamura, A.; Ito, T.; Ohnishi, H.; Koizumi, A.; Takeda, Y.

    2007-04-01

    We have investigated transport and magnetic properties in ErP ultrathin films grown on the GaInP (001) surface. Hall resistance and transverse magnetoresistance measurements yield the carrier density of ˜1.4×1020 cm-3 and the electron and hole mobilities of 1250-1450 cm2/Vs at 10 K. The resistivity anomaly in the longitudinal megnetoresistance is interpreted in terms of the spin-disorder scattering in the antiferromagnetic phase below 3.5 K.

  17. Field-Induced Magnetostructural Transitions in Antiferromagnetic Fe1+ y Te1- x S x

    Science.gov (United States)

    Tokunaga, M.; Kihara, T.; Mizuguchi, Y.; Takano, Y.

    2013-03-01

    Transport and structural properties of Fe1+ y Te1- x S x were studied in pulsed magnetic fields. Application of high magnetic fields induces first order transitions showing positive magnetoresistance effects in the antiferromagnetic phase. Polarizing microscope images taken at high magnetic fields revealed the concomitant melting of the orbital order. These results indicate the importance of crossed coupling between spin and lattice or orbital degrees of freedom in this compound.

  18. Anisotropic phase diagram and spin fluctuations of the hyperkagome magnet Gd3Ga5O12 as revealed by sound velocity measurements

    Science.gov (United States)

    Rousseau, Alexandre; Parent, Jean-Michel; Quilliam, Jeffrey A.

    2017-08-01

    Sound velocity and attenuation measurements on the frustrated garnet material Gd3Ga5O12 (GGG) are presented as a function of field and temperature, with two different magnetic field orientations: [100 ] and [110 ] . We demonstrate that the phase diagram is highly anisotropic, with two distinct field-induced ordered phases for H ||[110 ] and only one for H ||[100 ] . Extensive lattice softening is found to occur at low fields, which can be associated with spin fluctuations. However, deep within the spin liquid phase a low-temperature stiffening of the lattice and reduced attenuation provide evidence for a spin gap which may be related to short-range antiferromagnetic correlations over minimal ten-spin loops.

  19. Prediction for spin Fano factor generated by biased quantum spin chains

    Science.gov (United States)

    Aftergood, Joshua; Takei, So

    We theoretically study noise in the spin current injected into a normal metal from a 1D Heisenberg spin- 1 / 2 antiferromagnet. We consider the noise generated in two separate scenarios: first by inducing an over-population of one chiral mode relative to the other in the spin chain at uniform temperature, and second by elevating the temperature of the spin chain relative to the metal, i.e., by way of the spin Seebeck effect. We compute excess noise in the normal metal generated by the coupling to the spin chain and predict the spin Fano factor, defined as the noise in the spin current normalized by the average spin current, for both scenarios. The authors thank the PSC-CUNY Research Award Program for its support.

  20. Mean Field Theory of a Coupled Heisenberg Model and Its Application to an Organic Antiferromagnet with Magnetic Anions

    Science.gov (United States)

    Ito, Kazuhiro; Shimahara, Hiroshi

    2016-02-01

    We examine the mean field theory of a uniaxial coupled Heisenberg antiferromagnet with two subsystems, one of which consists of strongly interacting small spins and the other consists of weakly interacting large spins. We reanalyze the experimental data of specific heat and magnetic susceptibility obtained by previous authors for the organic compound λ-(BETS)2FeCl4 at low temperatures, where BETS stands for bis(ethylenedithio)tetraselenafulvalene. The model parameters for this compound are evaluated, where the applicability of the theory is checked. As a result, it is found that J1 ≫ J12 ≫ J2, where J1, J2, and J12 denote the exchange coupling constant between π spins, that between 3d spins, and that between π and 3d spins, respectively. At the low-temperature limit, both sublattice magnetizations of the 3d and π spins are saturated, and the present model is reduced to the Schottky model, which successfully explains experimental observations in previous studies. As temperature increases, fluctuations of 3d spins increase, while π spins remain almost saturated. Near the critical temperature, both spins fluctuate significantly, and thus the mean field approximation breaks down. It is revealed that the magnetic anisotropy, which may be crucial to the antiferromagnetic long-range order, originates from J12 rather than from J2 and that the angle between the magnetic easy-axis and the crystal c-axis is approximately 26-27° in the present effective model.

  1. Measurements of $t\\bar{t}$ spin correlations and top-quark polarization using dilepton final states in pp collisions at $\\sqrt{s}$ = 7 TeV

    CERN Document Server

    Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Luyckx, Sten; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Heracleous, Natalie; Kalogeropoulos, Alexis; Keaveney, James; Kim, Tae Jeong; Lowette, Steven; Maes, Michael; Olbrechts, Annik; Strom, Derek; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Favart, Laurent; Gay, Arnaud; Hreus, Tomas; Léonard, Alexandre; Marage, Pierre Edouard; Mohammadi, Abdollah; Perniè, Luca; Reis, Thomas; Seva, Tomislav; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Benucci, Leonardo; Cimmino, Anna; Costantini, Silvia; Dildick, Sven; Garcia, Guillaume; Klein, Benjamin; Lellouch, Jérémie; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Sigamani, Michael; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Walsh, Sinead; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Beluffi, Camille; Bruno, Giacomo; Castello, Roberto; Caudron, Adrien; Ceard, Ludivine; Da Silveira, Gustavo Gil; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Popov, Andrey; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; Martins, Thiago; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Malbouisson, Helena; Malek, Magdalena; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santaolalla, Javier; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Genchev, Vladimir; Iaydjiev, Plamen; Marinov, Andrey; Piperov, Stefan; Rodozov, Mircho; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Du, Ran; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Plestina, Roko; Tao, Junquan; Wang, Xianyou; Wang, Zheng; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Yifei; Li, Qiang; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Zhang, Linlin; Zou, Wei; Avila, Carlos; Carrillo Montoya, Camilo Andres; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Kadija, Kreso; Luetic, Jelena; Mekterovic, Darko; Morovic, Srecko; Tikvica, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Abdelalim, Ahmed Ali; Assran, Yasser; Elgammal, Sherif; Ellithi Kamel, Ali; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Müntel, Mait; Murumaa, Marion; Raidal, Martti; Rebane, Liis; Tiko, Andres; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami

    2014-05-05

    Spin correlations in the t-tbar quark system and the polarization of the top quark are measured using dilepton final states produced in pp collisions at the LHC at $\\sqrt{s}$=7 TeV. The data correspond to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector. The measurements are performed using events with two oppositely charged leptons (electrons or muons), a significant imbalance in transverse momentum, and two or more jets, where at least one of the jets is identified as likely originating from a b quark. The spin correlations and polarization are measured through asymmetries in angular distributions of the two selected leptons, unfolded to the parton level. All measurements are found to be in agreement with predictions of the standard model.

  2. Measurements of spin correlation in top-antitop quark events from proton-proton collisions at $\\sqrt{s}=7$ TeV using the ATLAS detector

    CERN Document Server

    Aad, Georges; Abdallah, Jalal; Abdel Khalek, Samah; Abdinov, Ovsat; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Abreu, Ricardo; Abulaiti, Yiming; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Adelman, Jahred; Adomeit, Stefanie; Adye, Tim; Agatonovic-Jovin, Tatjana; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahmadov, Faig; Aielli, Giulio; Akerstedt, Henrik; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alberghi, Gian Luigi; Albert, Justin; Albrand, Solveig; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Alimonti, Gianluca; Alio, Lion; Alison, John; Allbrooke, Benedict; Allison, Lee John; Allport, Phillip; Almond, John; Aloisio, Alberto; Alonso, Alejandro; Alonso, Francisco; Alpigiani, Cristiano; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral Coutinho, Yara; Amelung, Christoph; Amidei, Dante; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amram, Nir; Amundsen, Glenn; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Angelidakis, Stylianos; Angelozzi, Ivan; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Araque, Juan Pedro; Arce, Ayana; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arnold, Hannah; Arratia, Miguel; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Asai, Shoji; Asbah, Nedaa; Ashkenazi, Adi; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Atkinson, Markus; Atlay, Naim Bora; Auerbach, Benjamin; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baas, Alessandra; Bacci, Cesare; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Backus Mayes, John; Badescu, Elisabeta; Bagiacchi, Paolo; Bagnaia, Paolo; Bai, Yu; Bain, Travis; Baines, John; Baker, Oliver Keith; Balek, Petr; Balli, Fabrice; Banas, Elzbieta; Banerjee, Swagato; Bannoura, Arwa A E; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Barnovska, Zuzana; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartos, Pavol; Bartsch, Valeria; Bassalat, Ahmed; Basye, Austin; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Marco; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Becot, Cyril; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Beermann, Thomas; Begel, Michael; Behr, Katharina; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Beringer, Jürg; Bernard, Clare; Bernat, Pauline; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Berta, Peter; Bertella, Claudia; Bertoli, Gabriele; Bertolucci, Federico; Bertsche, David; Besana, Maria Ilaria; Besjes, Geert-Jan; Bessidskaia, Olga; Bessner, Martin Florian; Besson, Nathalie; Betancourt, Christopher; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilbao De Mendizabal, Javier; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Black, Curtis; Black, James; Black, Kevin; Blackburn, Daniel; Blair, Robert; Blanchard, Jean-Baptiste; Blazek, Tomas; Bloch, Ingo; Blocker, Craig; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Bock, Christopher; Boddy, Christopher Richard; Boehler, Michael; Boek, Thorsten Tobias; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Boldyrev, Alexey; Bomben, Marco; Bona, Marcella; Boonekamp, Maarten; Borisov, Anatoly; Borissov, Guennadi; Borri, Marcello; Borroni, Sara; Bortfeldt, Jonathan; Bortolotto, Valerio; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Boudreau, Joseph; Bouffard, Julian; Bouhova-Thacker, Evelina Vassileva; Boumediene, Djamel Eddine; Bourdarios, Claire; Bousson, Nicolas; Boutouil, Sara; Boveia, Antonio; Boyd, James; Boyko, Igor; Bracinik, Juraj; Brandt, Andrew; Brandt, Gerhard; Brandt, Oleg; Bratzler, Uwe; Brau, Benjamin; Brau, James; Braun, Helmut; Brazzale, Simone Federico; Brelier, Bertrand; Brendlinger, Kurt; Brennan, Amelia Jean; Brenner, Richard; Bressler, Shikma; Bristow, Kieran; Bristow, Timothy Michael; Britton, Dave; Brochu, Frederic; Brock, Ian; Brock, Raymond; Bromberg, Carl; Bronner, Johanna; Brooijmans, Gustaaf; Brooks, Timothy; Brooks, William; Brosamer, Jacquelyn; Brost, Elizabeth; Brown, Jonathan; Bruckman de Renstrom, Pawel; Bruncko, Dusan; Bruneliere, Renaud; Brunet, Sylvie; Bruni, Alessia; Bruni, Graziano; Bruschi, Marco; Bryngemark, Lene; Buanes, Trygve; Buat, Quentin; Bucci, Francesca; Buchholz, Peter; Buckingham, Ryan; Buckley, Andrew; Buda, Stelian Ioan; Budagov, Ioulian; Buehrer, Felix; Bugge, Lars; Bugge, Magnar Kopangen; Bulekov, Oleg; Bundock, Aaron Colin; Burckhart, Helfried; Burdin, Sergey; Burghgrave, Blake; Burke, Stephen; Burmeister, Ingo; Busato, Emmanuel; Büscher, Daniel; Büscher, Volker; Bussey, Peter; Buszello, Claus-Peter; Butler, Bart; Butler, John; Butt, Aatif Imtiaz; Buttar, Craig; Butterworth, Jonathan; Butti, Pierfrancesco; Buttinger, William; Buzatu, Adrian; Byszewski, Marcin; Cabrera Urbán, Susana; Caforio, Davide; Cakir, Orhan; Calafiura, Paolo; Calandri, Alessandro; Calderini, Giovanni; Calfayan, Philippe; Calkins, Robert; Caloba, Luiz; Calvet, David; Calvet, Samuel; Camacho Toro, Reina; Camarda, Stefano; Cameron, David; Caminada, Lea Michaela; Caminal Armadans, Roger; Campana, Simone; Campanelli, Mario; Campoverde, Angel; Canale, Vincenzo; Canepa, Anadi; Cano Bret, Marc; Cantero, Josu; Cantrill, Robert; Cao, Tingting; Capeans Garrido, Maria Del Mar; Caprini, Irinel; Caprini, Mihai; Capua, Marcella; Caputo, Regina; Cardarelli, Roberto; Carli, Tancredi; Carlino, Gianpaolo; Carminati, Leonardo; Caron, Sascha; Carquin, Edson; Carrillo-Montoya, German D; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Casolino, Mirkoantonio; Castaneda-Miranda, Elizabeth; Castelli, Angelantonio; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Catastini, Pierluigi; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cavaliere, Viviana; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Ceradini, Filippo; Cerio, Benjamin; Cerny, Karel; Santiago Cerqueira, Augusto; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cerv, Matevz; Cervelli, Alberto; Cetin, Serkant Ali; Chafaq, Aziz; Chakraborty, Dhiman; Chalupkova, Ina; Chang, Philip; Chapleau, Bertrand; Chapman, John Derek; Charfeddine, Driss; Charlton, Dave; Chau, Chav Chhiv; Chavez Barajas, Carlos Alberto; Cheatham, Susan; Chegwidden, Andrew; Chekanov, Sergei; Chekulaev, Sergey; Chelkov, Gueorgui; Chelstowska, Magda Anna; Chen, Chunhui; Chen, Hucheng; Chen, Karen; Chen, Liming; Chen, Shenjian; Chen, Xin; Chen, Yujiao; Cheng, Hok Chuen; Cheng, Yangyang; Cheplakov, Alexander; Cherkaoui El Moursli, Rajaa; Chernyatin, Valeriy; Cheu, Elliott; Chevalier, Laurent; Chiarella, Vitaliano; Chiefari, Giovanni; Childers, John Taylor; Chilingarov, Alexandre; Chiodini, Gabriele; Chisholm, Andrew; Chislett, Rebecca Thalatta; Chitan, Adrian; Chizhov, Mihail; Chouridou, Sofia; Chow, Bonnie Kar Bo; Chromek-Burckhart, Doris; Chu, Ming-Lee; Chudoba, Jiri; Chwastowski, Janusz; Chytka, Ladislav; Ciapetti, Guido; Ciftci, Abbas Kenan; Ciftci, Rena; Cinca, Diane; Cindro, Vladimir; Ciocio, Alessandra; Cirkovic, Predrag; Citron, Zvi Hirsh; Citterio, Mauro; Ciubancan, Mihai; Clark, Allan G; Clark, Philip James; Clarke, Robert; Cleland, Bill; Clemens, Jean-Claude; Clement, Christophe; Coadou, Yann; Cobal, Marina; Coccaro, Andrea; Cochran, James H; Coffey, Laurel; Cogan, Joshua Godfrey; Coggeshall, James; Cole, Brian; Cole, Stephen; Colijn, Auke-Pieter; Collot, Johann; Colombo, Tommaso; Colon, German; Compostella, Gabriele; Conde Muiño, Patricia; Coniavitis, Elias; Conidi, Maria Chiara; Connell, Simon Henry; Connelly, Ian; Consonni, Sofia Maria; Consorti, Valerio; Constantinescu, Serban; Conta, Claudio; Conti, Geraldine; Conventi, Francesco; Cooke, Mark; Cooper, Ben; Cooper-Sarkar, Amanda; Cooper-Smith, Neil; Copic, Katherine; Cornelissen, Thijs; Corradi, Massimo; Corriveau, Francois; Corso-Radu, Alina; Cortes-Gonzalez, Arely; Cortiana, Giorgio; Costa, Giuseppe; Costa, María José; Costanzo, Davide; Côté, David; Cottin, Giovanna; Cowan, Glen; Cox, Brian; Cranmer, Kyle; Cree, Graham; Crépé-Renaudin, Sabine; Crescioli, Francesco; Cribbs, Wayne Allen; Crispin Ortuzar, Mireia; Cristinziani, Markus; Croft, Vince; Crosetti, Giovanni; Cuciuc, Constantin-Mihai; Cuhadar Donszelmann, Tulay; Cummings, Jane; Curatolo, Maria; Cuthbert, Cameron; Czirr, Hendrik; Czodrowski, Patrick; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; Da Cunha Sargedas De Sousa, Mario Jose; Da Via, Cinzia; Dabrowski, Wladyslaw; Dafinca, Alexandru; Dai, Tiesheng; Dale, Orjan; Dallaire, Frederick; Dallapiccola, Carlo; Dam, Mogens; Daniells, Andrew Christopher; Dano Hoffmann, Maria; Dao, Valerio; Darbo, Giovanni; Darmora, Smita; Dassoulas, James; Dattagupta, Aparajita; Davey, Will; David, Claire; Davidek, Tomas; Davies, Eleanor; Davies, Merlin; Davignon, Olivier; Davison, Adam; Davison, Peter; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Daya-Ishmukhametova, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Cecco, Sandro; De Groot, Nicolo; de Jong, Paul; De la Torre, Hector; De Lorenzi, Francesco; De Nooij, Lucie; De Pedis, Daniele; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; Dearnaley, William James; Debbe, Ramiro; Debenedetti, Chiara; Dechenaux, Benjamin; Dedovich, Dmitri; Deigaard, Ingrid; Del Peso, Jose; Del Prete, Tarcisio; Deliot, Frederic; Delitzsch, Chris Malena; Deliyergiyev, Maksym; Dell'Acqua, Andrea; Dell'Asta, Lidia; Dell'Orso, Mauro; Della Pietra, Massimo; della Volpe, Domenico; Delmastro, Marco; Delsart, Pierre-Antoine; Deluca, Carolina; Demers, Sarah; Demichev, Mikhail; Demilly, Aurelien; Denisov, Sergey; Derendarz, Dominik; Derkaoui, Jamal Eddine; Derue, Frederic; Dervan, Paul; Desch, Klaus Kurt; Deterre, Cecile; Deviveiros, Pier-Olivier; Dewhurst, Alastair; Dhaliwal, Saminder; Di Ciaccio, Anna; Di Ciaccio, Lucia; Di Domenico, Antonio; Di Donato, Camilla; Di Girolamo, Alessandro; Di Girolamo, Beniamino; Di Mattia, Alessandro; Di Micco, Biagio; Di Nardo, Roberto; Di Simone, Andrea; Di Sipio, Riccardo; Di Valentino, David; Dias, Flavia; Diaz, Marco Aurelio; Diehl, Edward; Dietrich, Janet; Dietzsch, Thorsten; Diglio, Sara; Dimitrievska, Aleksandra; Dingfelder, Jochen; Dionisi, Carlo; Dita, Petre; Dita, Sanda; Dittus, Fridolin; Djama, Fares; Djobava, Tamar; Barros do Vale, Maria Aline; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobos, Daniel; Doglioni, Caterina; Doherty, Tom; Dohmae, Takeshi; Dolejsi, Jiri; Dolezal, Zdenek; Dolgoshein, Boris; Donadelli, Marisilvia; Donati, Simone; Dondero, Paolo; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dova, Maria-Teresa; Doyle, Tony; Dris, Manolis; Dubbert, Jörg; Dube, Sourabh; Dubreuil, Emmanuelle; Duchovni, Ehud; Duckeck, Guenter; Ducu, Otilia Anamaria; Duda, Dominik; Dudarev, Alexey; Dudziak, Fanny; Duflot, Laurent; Duguid, Liam; Dührssen, Michael; Dunford, Monica; Duran Yildiz, Hatice; Düren, Michael; Durglishvili, Archil; Dwuznik, Michal; Dyndal, Mateusz; Ebke, Johannes; Edson, William; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Emeliyanov, Dmitry; Enari, Yuji; Endner, Oliver Chris; Endo, Masaki; Engelmann, Roderich; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernis, Gunar; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Esch, Hendrik; Escobar, Carlos; Esposito, Bellisario; Etienvre, Anne-Isabelle; Etzion, Erez; Evans, Hal; Ezhilov, Alexey; Fabbri, Laura; Facini, Gabriel; Fakhrutdinov, Rinat; Falciano, Speranza; Falla, Rebecca Jane; Faltova, Jana; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farooque, Trisha; Farrell, Steven; Farrington, Sinead; Farthouat, Philippe; Fassi, Farida; Fassnacht, Patrick; Fassouliotis, Dimitrios; Favareto, Andrea; Fayard, Louis; Federic, Pavol; Fedin, Oleg; Fedorko, Wojciech; Fehling-Kaschek, Mirjam; Feigl, Simon; Feligioni, Lorenzo; Feng, Cunfeng; Feng, Eric; Feng, Haolu; Fenyuk, Alexander; Fernandez Perez, Sonia; Ferrag, Samir; Ferrando, James; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filipuzzi, Marco; Filthaut, Frank; Fincke-Keeler, Margret; Finelli, Kevin Daniel; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Adam; Fischer, Julia; Fisher, Wade Cameron; Fitzgerald, Eric Andrew; Flechl, Martin; Fleck, Ivor; Fleischmann, Philipp; Fleischmann, Sebastian; Fletcher, Gareth Thomas; Fletcher, Gregory; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Florez Bustos, Andres Carlos; Flowerdew, Michael; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Fournier, Daniel; Fox, Harald; Fracchia, Silvia; Francavilla, Paolo; Franchini, Matteo; Franchino, Silvia; Francis, David; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; French, Sky; Friedrich, Conrad; Friedrich, Felix; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fulsom, Bryan Gregory; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gabrielli, Alessandro; Gabrielli, Andrea; Gadatsch, Stefan; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Galhardo, Bruno; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Galster, Gorm Aske Gram Krohn; Gan, KK; Gandrajula, Reddy Pratap; Gao, Jun; Gao, Yongsheng; Garay Walls, Francisca; Garberson, Ford; García, Carmen; García Navarro, José Enrique; Garcia-Sciveres, Maurice; Gardner, Robert; Garelli, Nicoletta; Garonne, Vincent; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gauzzi, Paolo; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gazis, Evangelos; Ge, Peng; Gecse, Zoltan; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerbaudo, Davide; Gershon, Avi; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giangiobbe, Vincent; Giannetti, Paola; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Stephen; Gilchriese, Murdock; Gillam, Thomas; Gillberg, Dag; Gilles, Geoffrey; Gingrich, Douglas; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Filippo Maria; Giorgi, Francesco Michelangelo; Giraud, Pierre-Francois; Giugni, Danilo; Giuliani, Claudia; Giulini, Maddalena; Gjelsten, Børge Kile; Gkaitatzis, Stamatios; Gkialas, Ioannis; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glaysher, Paul; Glazov, Alexandre; Glonti, George; Goblirsch-Kolb, Maximilian; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goeringer, Christian; Goldfarb, Steven; Golling, Tobias; Golubkov, Dmitry; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez-Sevilla, Sergio; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Goshaw, Alfred; Gössling, Claus; Gostkin, Mikhail Ivanovitch; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabas, Herve Marie Xavier; Graber, Lars; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Gramling, Johanna; Gramstad, Eirik; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Gray, Heather; Graziani, Enrico; Grebenyuk, Oleg; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grillo, Alexander; Grimm, Kathryn; Grinstein, Sebastian; Gris, Philippe Luc Yves; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Grohs, Johannes Philipp; Grohsjean, Alexander; Gross, Eilam; Grosse-Knetter, Joern; Grossi, Giulio Cornelio; Groth-Jensen, Jacob; Grout, Zara Jane; Guan, Liang; Guescini, Francesco; Guest, Daniel; Gueta, Orel; Guicheney, Christophe; Guido, Elisa; Guillemin, Thibault; Guindon, Stefan; Gul, Umar; Gumpert, Christian; Gunther, Jaroslav; Guo, Jun; Gupta, Shaun; Gutierrez, Phillip; Gutierrez Ortiz, Nicolas Gilberto; Gutschow, Christian; Guttman, Nir; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haber, Carl; Hadavand, Haleh Khani; Haddad, Nacim; Haefner, Petra; Hageböck, Stephan; Hajduk, Zbigniew; Hakobyan, Hrachya; Haleem, Mahsana; Hall, David; Halladjian, Garabed; Hamacher, Klaus; Hamal, Petr; Hamano, Kenji; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Hamnett, Phillip George; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Hanke, Paul; Hanna, Remie; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hara, Kazuhiko; Hard, Andrew; Harenberg, Torsten; Hariri, Faten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Paul Fraser; Hartjes, Fred; Hasegawa, Satoshi; Hasegawa, Yoji; Hasib, A; Hassani, Samira; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hayashi, Takayasu; Hayden, Daniel; Hays, Chris; Hayward, Helen; Haywood, Stephen; Head, Simon; Heck, Tobias; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heim, Timon; Heinemann, Beate; Heinrich, Lukas; Hejbal, Jiri; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, James; Henderson, Robert; Heng, Yang; Hengler, Christopher; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Hensel, Carsten; Herbert, Geoffrey Henry; Hernández Jiménez, Yesenia; Herrberg-Schubert, Ruth; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Hickling, Robert; Higón-Rodriguez, Emilio; Hill, Ewan; Hill, John; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hofmann, Julia Isabell; Hohlfeld, Marc; Holmes, Tova Ray; Hong, Tae Min; Hooft van Huysduynen, Loek; Hostachy, Jean-Yves; Hou, Suen; Hoummada, Abdeslam; Howard, Jacob; Howarth, James; Hrabovsky, Miroslav; Hristova, Ivana; Hrivnac, Julius; Hryn'ova, Tetiana; Hsu, Catherine; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Hu, Diedi; Hu, Xueye; Huang, Yanping; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Huhtinen, Mika; Hülsing, Tobias Alexander; Hurwitz, Martina; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibragimov, Iskander; Iconomidou-Fayard, Lydia; Ideal, Emma; Iengo, Paolo; Igonkina, Olga; Iizawa, Tomoya; Ikegami, Yoichi; Ikematsu, Katsumasa; Ikeno, Masahiro; Ilchenko, Iurii; Iliadis, Dimitrios; Ilic, Nikolina; Inamaru, Yuki; Ince, Tayfun; Ioannou, Pavlos; Iodice, Mauro; Iordanidou, Kalliopi; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishino, Masaya; Ishitsuka, Masaki; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Iturbe Ponce, Julia Mariana; Iuppa, Roberto; Ivarsson, Jenny; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, Matthew; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakoubek, Tomas; Jakubek, Jan; Jamin, David Olivier; Jana, Dilip; Jansen, Eric; Jansen, Hendrik; Janssen, Jens; Janus, Michel; Jarlskog, Göran; Javadov, Namig; Javůrek, Tomáš; Jeanty, Laura; Jejelava, Juansher; Jeng, Geng-yuan; Jennens, David; Jenni, Peter; Jentzsch, Jennifer; Jeske, Carl; Jézéquel, Stéphane; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Shan; Jinaru, Adam; Jinnouchi, Osamu; Joergensen, Morten Dam; Johansson, Erik; Johansson, Per; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tim; Jongmanns, Jan; Jorge, Pedro; Joshi, Kiran Daniel; Jovicevic, Jelena; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Jussel, Patrick; Juste Rozas, Aurelio; Kaci, Mohammed; Kaczmarska, Anna; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kajomovitz, Enrique; Kalderon, Charles William; Kama, Sami; Kamenshchikov, Andrey; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kar, Deepak; Karakostas, Konstantinos; Karastathis, Nikolaos; Karnevskiy, Mikhail; Karpov, Sergey; Karpova, Zoya; Karthik, Krishnaiyengar; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Yousuke; Katre, Akshay; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kazama, Shingo; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Kehoe, Robert; Keil, Markus; Keller, John; Kempster, Jacob Julian; Keoshkerian, Houry; Kepka, Oldrich; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Khodinov, Alexander; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hee Yeun; Kim, Hyeon Jin; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; King, Samuel Burton; Kirk, Julie; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kiss, Florian; Kittelmann, Thomas; Kiuchi, Kenji; Kladiva, Eduard; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klioutchnikova, Tatiana; Klok, Peter; Kluge, Eike-Erik; Kluit, Peter; Kluth, Stefan; Kneringer, Emmerich; Knoops, Edith; Knue, Andrea; Kobayashi, Dai; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohlmann, Simon; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kolanoski, Hermann; Koletsou, Iro; Koll, James; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kondrashova, Nataliia; Köneke, Karsten; König, Adriaan; König, Sebastian; Kono, Takanori; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kopeliansky, Revital; Koperny, Stefan; Köpke, Lutz; Kopp, Anna Katharina; Korcyl, Krzysztof; Kordas, Kostantinos; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasnopevtsev, Dimitriy; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, Jana; Kravchenko, Anton; Kreiss, Sven; Kretz, Moritz; Kretzschmar, Jan; Kreutzfeldt, Kristof; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruse, Amanda; Kruse, Mark; Kruskal, Michael; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Andrew; Kuhl, Thorsten; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kuna, Marine; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurochkin, Yurii; Kurumida, Rie; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; La Rosa, Alessandro; La Rotonda, Laura; Lacasta, Carlos; Lacava, Francesco; Lacey, James; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laier, Heiko; Lambourne, Luke; Lammers, Sabine; Lampen, Caleb; Lampl, Walter; Lançon, Eric; Landgraf, Ulrich; Landon, Murrough; Lang, Valerie Susanne; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Lassnig, Mario; Laurelli, Paolo; Lavrijsen, Wim; Law, Alexander; Laycock, Paul; Le, Bao Tran; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Menedeu, Eve; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Claire Alexandra; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Guillaume; Lefebvre, Michel; Legger, Federica; Leggett, Charles; Lehan, Allan; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leight, William Axel; Leisos, Antonios; Leister, Andrew Gerard; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Lemmer, Boris; Leney, Katharine; Lenz, Tatjana; Lenzen, Georg; Lenzi, Bruno; Leone, Robert; Leone, Sandra; Leonhardt, Kathrin; Leonidopoulos, Christos; Leontsinis, Stefanos; Leroy, Claude; Lester, Christopher; Lester, Christopher Michael; Levchenko, Mikhail; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levy, Mark; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bing; Li, Bo; Li, Haifeng; Li, Ho Ling; Li, Lei; Li, Liang; Li, Shu; Li, Yichen; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lie, Ki; Liebal, Jessica; Liebig, Wolfgang; Limbach, Christian; Limosani, Antonio; Lin, Simon; Lin, Tai-Hua; Linde, Frank; Lindquist, Brian Edward; Linnemann, James; Lipeles, Elliot; Lipniacka, Anna; Lisovyi, Mykhailo; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Bo; Liu, Dong; Liu, Jianbei; Liu, Kun; Liu, Lulu; Liu, Miaoyuan; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lo Sterzo, Francesco; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loevschall-Jensen, Ask Emil; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Lombardo, Vincenzo Paolo; Long, Brian Alexander; Long, Jonathan; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lopez Paredes, Brais; Lopez Paz, Ivan; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lou, XinChou; Lounis, Abdenour; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Luehring, Frederick; Lukas, Wolfgang; Luminari, Lamberto; Lundberg, Olof; Lund-Jensen, Bengt; Lungwitz, Matthias; Lynn, David; Lysak, Roman; Lytken, Else; Ma, Hong; Ma, Lian Liang; Maccarrone, Giovanni; Macchiolo, Anna; Machado Miguens, Joana; Macina, Daniela; Madaffari, Daniele; Madar, Romain; Maddocks, Harvey Jonathan; Mader, Wolfgang; Madsen, Alexander; Maeno, Mayuko; Maeno, Tadashi; Magradze, Erekle; Mahboubi, Kambiz; Mahlstedt, Joern; Mahmoud, Sara; Maiani, Camilla; Maidantchik, Carmen; Maier, Andreas Alexander; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mamuzic, Judita; Mandelli, Beatrice; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Manfredini, Alessandro; Manhaes de Andrade Filho, Luciano; Manjarres Ramos, Joany Andreina; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Mantifel, Rodger; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marjanovic, Marija; Marques, Carlos; Marroquim, Fernando; Marsden, Stephen Philip; Marshall, Zach; Marti, Lukas Fritz; Marti-Garcia, Salvador; Martin, Brian; Martin, Brian Thomas; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martinez, Homero; Martinez, Mario; Martin-Haugh, Stewart; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Mättig, Peter; Mattmann, Johannes; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; Mazini, Rachid; Mazzaferro, Luca; Mc Goldrick, Garrin; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; Mchedlidze, Gvantsa; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Medinnis, Michael; Meehan, Samuel; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meineck, Christian; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Meloni, Federico; Mengarelli, Alberto; Menke, Sven; Meoni, Evelin; Mercurio, Kevin Michael; Mergelmeyer, Sebastian; Meric, Nicolas; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Milic, Adriana; Miller, David; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Mitani, Takashi; Mitrevski, Jovan; Mitsou, Vasiliki A; Mitsui, Shingo; Miucci, Antonio; Miyagawa, Paul; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mochizuki, Kazuya; Mohapatra, Soumya; Mohr, Wolfgang; Molander, Simon; Moles-Valls, Regina; Mönig, Klaus; Monini, Caterina; Monk, James; Monnier, Emmanuel; Montejo Berlingen, Javier; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moraes, Arthur; Morange, Nicolas; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Moritz, Sebastian; Morley, Anthony Keith; Mornacchi, Giuseppe; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Motohashi, Kazuki; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Muanza, Steve; Mudd, Richard; Mueller, Felix; Mueller, James; Mueller, Klemens; Mueller, Thibaut; Mueller, Timo; Muenstermann, Daniel; Munwes, Yonathan; Murillo Quijada, Javier Alberto; Murray, Bill; Musheghyan, Haykuhi; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nackenhorst, Olaf; Nadal, Jordi; Nagai, Koichi; Nagai, Ryo; Nagai, Yoshikazu; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Namasivayam, Harisankar; Nanava, Gizo; Narayan, Rohin; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Nayyar, Ruchika; Neal, Homer; Nechaeva, Polina; Neep, Thomas James; Nef, Pascal Daniel; Negri, Andrea; Negri, Guido; Negrini, Matteo; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neumann, Manuel; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen, Duong Hai; Nickerson, Richard; Nicolaidou, Rosy; Nicquevert, Bertrand; Nielsen, Jason; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nisius, Richard; Nobe, Takuya; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Norberg, Scarlet; Nordberg, Markus; Novgorodova, Olga; Nowak, Sebastian; Nozaki, Mitsuaki; Nozka, Libor; Ntekas, Konstantinos; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; Nuti, Francesco; O'Brien, Brendan Joseph; O'grady, Fionnbarr; O'Neil, Dugan; O'Shea, Val; Oakham, Gerald; Oberlack, Horst; Obermann, Theresa; Ocariz, Jose; Ochi, Atsuhiko; Ochoa, Ines; Oda, Susumu; Odaka, Shigeru; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohman, Henrik; Ohshima, Takayoshi; Okamura, Wataru; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olszewski, Andrzej; Olszowska, Jolanta; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Otero y Garzon, Gustavo; Otono, Hidetoshi; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Oussoren, Koen Pieter; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pachal, Katherine; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagáčová, Martina; Pagan Griso, Simone; Paganis, Efstathios; Pahl, Christoph; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Palestini, Sandro; Palka, Marek; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panduro Vazquez, William; Pani, Priscilla; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Paolozzi, Lorenzo; Papadopoulou, Theodora; Papageorgiou, Konstantinos; Paramonov, Alexander; Paredes Hernandez, Daniela; Parker, Michael Andrew; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pearce, James; Pedersen, Maiken; Pedraza Lopez, Sebastian; Pedro, Rute; Peleganchuk, Sergey; Pelikan, Daniel; Peng, Haiping; Penning, Bjoern; Penwell, John; Perepelitsa, Dennis; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Peschke, Richard; Peshekhonov, Vladimir; Peters, Krisztian; Peters, Yvonne; Petersen, Brian; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Pettersson, Nora Emilia; Pezoa, Raquel; Phillips, Peter William; Piacquadio, Giacinto; Pianori, Elisabetta; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piegaia, Ricardo; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Pingel, Almut; Pinto, Belmiro; Pires, Sylvestre; Pitt, Michael; Pizio, Caterina; Plazak, Lukas; Pleier, Marc-Andre; Pleskot, Vojtech; Plotnikova, Elena; Plucinski, Pawel; Poddar, Sahill; Podlyski, Fabrice; Poettgen, Ruth; Poggioli, Luc; Pohl, David-leon; Pohl, Martin; Polesello, Giacomo; Policicchio, Antonio; Polifka, Richard; Polini, Alessandro; Pollard, Christopher Samuel; Polychronakos, Venetios; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Pospisil, Stanislav; Potamianos, Karolos; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Price, Darren; Price, Joe; Price, Lawrence; Prieur, Damien; Primavera, Margherita; Proissl, Manuel; Prokofiev, Kirill; Prokoshin, Fedor; Protopapadaki, Eftychia-sofia; Protopopescu, Serban; Proudfoot, James; Przybycien, Mariusz; Przysiezniak, Helenka; Ptacek, Elizabeth; Puddu, Daniele; Pueschel, Elisa; Puldon, David; Purohit, Milind; Puzo, Patrick; Qian, Jianming; Qin, Gang; Qin, Yang; Quadt, Arnulf; Quarrie, David; Quayle, William; Queitsch-Maitland, Michaela; Quilty, Donnchadha; Qureshi, Anum; Radeka, Veljko; Radescu, Voica; Radhakrishnan, Sooraj Krishnan; Radloff, Peter; Rados, Pere; Ragusa, Francesco; Rahal, Ghita; Rajagopalan, Srinivasan; Rammensee, Michael; Randle-Conde, Aidan Sean; Rangel-Smith, Camila; Rao, Kanury; Rauscher, Felix; Rave, Tobias Christian; Ravenscroft, Thomas; Raymond, Michel; Read, Alexander Lincoln; Readioff, Nathan Peter; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Rehnisch, Laura; Reisin, Hernan; Relich, Matthew; Rembser, Christoph; Ren, Huan; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Rezanova, Olga; Reznicek, Pavel; Rezvani, Reyhaneh; Richter, Robert; Ridel, Melissa; Rieck, Patrick; Rieger, Julia; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Ritsch, Elmar; Riu, Imma; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Roda, Chiara; Rodrigues, Luis; Roe, Shaun; Røhne, Ole; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romero Adam, Elena; Rompotis, Nikolaos; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Matthew; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rosten, Rachel; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexandre; Rozen, Yoram; Ruan, Xifeng; Rubbo, Francesco; Rubinskiy, Igor; Rud, Viacheslav; Rudolph, Christian; Rudolph, Matthew Scott; Rühr, Frederik; Ruiz-Martinez, Aranzazu; Rurikova, Zuzana; Rusakovich, Nikolai; Ruschke, Alexander; Rutherfoord, John; Ruthmann, Nils; Ryabov, Yury; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Saavedra, Aldo; Sacerdoti, Sabrina; Saddique, Asif; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Sakurai, Yuki; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salek, David; Sales De Bruin, Pedro Henrique; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Sanchez, Arturo; Sánchez, Javier; Sanchez Martinez, Victoria; Sandaker, Heidi; Sandbach, Ruth Laura; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandoval, Carlos; Sandstroem, Rikard; Sankey, Dave; Sansoni, Andrea; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Santoyo Castillo, Itzebelt; Sapp, Kevin; Sapronov, Andrey; Saraiva, João; Sarrazin, Bjorn; Sartisohn, Georg; Sasaki, Osamu; Sasaki, Yuichi; Sauvage, Gilles; Sauvan, Emmanuel; Savard, Pierre; Savu, Dan Octavian; Sawyer, Craig; Sawyer, Lee; Saxon, David; Saxon, James; Sbarra, Carla; Sbrizzi, Antonio; Scanlon, Tim; Scannicchio, Diana; Scarcella, Mark; Scarfone, Valerio; Schaarschmidt, Jana; Schacht, Peter; Schaefer, Douglas; Schaefer, Ralph; Schaepe, Steffen; Schaetzel, Sebastian; Schäfer, Uli; Schaffer, Arthur; Schaile, Dorothee; Schamberger, R~Dean; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schillo, Christian; Schioppa, Marco; Schlenker, Stefan; Schmidt, Evelyn; Schmieden, Kristof; Schmitt, Christian; Schmitt, Christopher; Schmitt, Sebastian; Schneider, Basil; Schnellbach, Yan Jie; Schnoor, Ulrike; Schoeffel, Laurent; Schoening, Andre; Schoenrock, Bradley Daniel; Schorlemmer, Andre Lukas; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schramm, Steven; Schreyer, Manuel; Schroeder, Christian; Schuh, Natascha; Schultens, Martin Johannes; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwanenberger, Christian; Schwartzman, Ariel; Schwegler, Philipp; Schwemling, Philippe; Schwienhorst, Reinhard; Schwindling, Jerome; Schwindt, Thomas; Schwoerer, Maud; Sciacca, Gianfranco; Scifo, Estelle; Sciolla, Gabriella; Scott, Bill; Scuri, Fabrizio; Scutti, Federico; Searcy, Jacob; Sedov, George; Sedykh, Evgeny; Seidel, Sally; Seiden, Abraham; Seifert, Frank; Seixas, José; Sekhniaidze, Givi; Sekula, Stephen; Selbach, Karoline Elfriede; Seliverstov, Dmitry; Sellers, Graham; Semprini-Cesari, Nicola; Serfon, Cedric; Serin, Laurent; Serkin, Leonid; Serre, Thomas; Seuster, Rolf; Severini, Horst; Sfiligoj, Tina; Sforza, Federico; Sfyrla, Anna; Shabalina, Elizaveta; Shamim, Mansoora; Shan, Lianyou; Shang, Ruo-yu; Shank, James; Shapiro, Marjorie; Shatalov, Pavel; Shaw, Kate; Shehu, Ciwake Yusufu; Sherwood, Peter; Shi, Liaoshan; Shimizu, Shima; Shimmin, Chase Owen; Shimojima, Makoto; Shiyakova, Mariya; Shmeleva, Alevtina; Shochet, Mel; Short, Daniel; Shrestha, Suyog; Shulga, Evgeny; Shupe, Michael; Shushkevich, Stanislav; Sicho, Petr; Sidiropoulou, Ourania; Sidorov, Dmitri; Sidoti, Antonio; Siegert, Frank; Sijacki, Djordje; Silva, José; Silver, Yiftah; Silverstein, Daniel; Silverstein, Samuel; Simak, Vladislav; Simard, Olivier; Simic, Ljiljana; Simion, Stefan; Simioni, Eduard; Simmons, Brinick; Simoniello, Rosa; Simonyan, Margar; Sinervo, Pekka; Sinev, Nikolai; Sipica, Valentin; Siragusa, Giovanni; Sircar, Anirvan; Sisakyan, Alexei; Sivoklokov, Serguei; Sjölin, Jörgen; Sjursen, Therese; Skottowe, Hugh Philip; Skovpen, Kirill; Skubic, Patrick; Slater, Mark; Slavicek, Tomas; Sliwa, Krzysztof; Smakhtin, Vladimir; Smart, Ben; Smestad, Lillian; Smirnov, Sergei; Smirnov, Yury; Smirnova, Lidia; Smirnova, Oxana; Smith, Kenway; Smizanska, Maria; Smolek, Karel; Snesarev, Andrei; Snidero, Giacomo; Snyder, Scott; Sobie, Randall; Socher, Felix; Soffer, Abner; Soh, Dart-yin; Solans, Carlos; Solar, Michael; Solc, Jaroslav; Soldatov, Evgeny; Soldevila, Urmila; Solfaroli Camillocci, Elena; Solodkov, Alexander; Soloshenko, Alexei; Solovyanov, Oleg; Solovyev, Victor; Sommer, Philip; Song, Hong Ye; Soni, Nitesh; Sood, Alexander; Sopczak, Andre; Sopko, Bruno; Sopko, Vit; Sorin, Veronica; Sosebee, Mark; Soualah, Rachik; Soueid, Paul; Soukharev, Andrey; South, David; Spagnolo, Stefania; Spanò, Francesco; Spearman, William Robert; Spettel, Fabian; Spighi, Roberto; Spigo, Giancarlo; Spousta, Martin; Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Staerz, Steffen; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stanescu-Bellu, Madalina; Stanitzki, Marcel Michael; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staszewski, Rafal; Stavina, Pavel; Steinberg, Peter; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stern, Sebastian; Stewart, Graeme; Stillings, Jan Andre; Stockton, Mark; Stoebe, Michael; Stoicea, Gabriel; Stolte, Philipp; Stonjek, Stefan; Stradling, Alden; Straessner, Arno; Stramaglia, Maria Elena; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Stroynowski, Ryszard; Stucci, Stefania Antonia; Stugu, Bjarne; Styles, Nicholas Adam; Su, Dong; Su, Jun; Subramania, Halasya Siva; Subramaniam, Rajivalochan; Succurro, Antonella; Sugaya, Yorihito; Suhr, Chad; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Svatos, Michal; Swedish, Stephen; Swiatlowski, Maximilian; Sykora, Ivan; Sykora, Tomas; Ta, Duc; Taccini, Cecilia; Tackmann, Kerstin; Taenzer, Joe; Taffard, Anyes; Tafirout, Reda; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Takubo, Yosuke; Talby, Mossadek; Talyshev, Alexey; Tam, Jason; Tan, Kong Guan; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanasijczuk, Andres Jorge; Tannenwald, Benjamin Bordy; Tannoury, Nancy; Tapprogge, Stefan; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tashiro, Takuya; Tassi, Enrico; Tavares Delgado, Ademar; Tayalati, Yahya; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teischinger, Florian Alfred; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Teoh, Jia Jian; Terada, Susumu; Terashi, Koji; Terron, Juan; Terzo, Stefano; Testa, Marianna; Teuscher, Richard; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thomas, Juergen; Thomas-Wilsker, Joshuha; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomsen, Lotte Ansgaard; Thomson, Evelyn; Thomson, Mark; Thong, Wai Meng; Thun, Rudolf; Tian, Feng; Tibbetts, Mark James; Tikhomirov, Vladimir; Tikhonov, Yury; Timoshenko, Sergey; Tiouchichine, Elodie; Tipton, Paul; Tisserant, Sylvain; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokushuku, Katsuo; Tollefson, Kirsten; Tomlinson, Lee; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Topilin, Nikolai; Torrence, Eric; Torres, Heberth; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Tran, Huong Lan; Trefzger, Thomas; Tremblet, Louis; Tricoli, Alessandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Tripiana, Martin; Triplett, Nathan; Trischuk, William; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trovatelli, Monica; True, Patrick; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsirintanis, Nikolaos; Tsiskaridze, Shota; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsuno, Soshi; Tsybychev, Dmitri; Tudorache, Alexandra; Tudorache, Valentina; Tuna, Alexander Naip; Tupputi, Salvatore; Turchikhin, Semen; Turecek, Daniel; Turk Cakir, Ilkay; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ughetto, Michael; Ugland, Maren; Uhlenbrock, Mathias; Ukegawa, Fumihiko; Unal, Guillaume; Undrus, Alexander; Unel, Gokhan; Ungaro, Francesca; Unno, Yoshinobu; Urbaniec, Dustin; Urquijo, Phillip; Usai, Giulio; Usanova, Anna; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Valencic, Nika; Valentinetti, Sara; Valero, Alberto; Valery, Loic; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; Van Den Wollenberg, Wouter; Van Der Deijl, Pieter; van der Geer, Rogier; van der Graaf, Harry; Van Der Leeuw, Robin; van der Ster, Daniel; van Eldik, Niels; van Gemmeren, Peter; Van Nieuwkoop, Jacobus; van Vulpen, Ivo; van Woerden, Marius Cornelis; Vanadia, Marco; Vandelli, Wainer; Vanguri, Rami; Vaniachine, Alexandre; Vankov, Peter; Vannucci, Francois; Vardanyan, Gagik; Vari, Riccardo; Varnes, Erich; Varol, Tulin; Varouchas, Dimitris; Vartapetian, Armen; Varvell, Kevin; Vazeille, Francois; Vazquez Schroeder, Tamara; Veatch, Jason; Veloso, Filipe; Veneziano, Stefano; Ventura, Andrea; Ventura, Daniel; Venturi, Manuela; Venturi, Nicola; Venturini, Alessio; Vercesi, Valerio; Verducci, Monica; Verkerke, Wouter; Vermeulen, Jos; Vest, Anja; Vetterli, Michel; Viazlo, Oleksandr; Vichou, Irene; Vickey, Trevor; Vickey Boeriu, Oana Elena; Viehhauser, Georg; Viel, Simon; Vigne, Ralph; Villa, Mauro; Villaplana Perez, Miguel; Vilucchi, Elisabetta; Vincter, Manuella; Vinogradov, Vladimir; Virzi, Joseph; Vivarelli, Iacopo; Vives Vaque, Francesc; Vlachos, Sotirios; Vladoiu, Dan; Vlasak, Michal; Vogel, Adrian; Vogel, Marcelo; Vokac, Petr; Volpi, Guido; Volpi, Matteo; von der Schmitt, Hans; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorobev, Konstantin; Vos, Marcel; Voss, Rudiger; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Vykydal, Zdenek; Wagner, Peter; Wagner, Wolfgang; Wahlberg, Hernan; Wahrmund, Sebastian; Wakabayashi, Jun; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Walsh, Brian; Wang, Chao; Wang, Chiho; Wang, Fuquan; Wang, Haichen; Wang, Hulin; Wang, J