WorldWideScience

Sample records for spin wave research

  1. Spin-Wave Diode

    Directory of Open Access Journals (Sweden)

    Jin Lan (兰金

    2015-12-01

    Full Text Available A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.

  2. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

    1975-01-01

    with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results......, which are corrected for the effect of the direct coupling between the magnons and the phonons, and for the field dependence of the relative magnetization at finite temperatures. A large q⃗-dependent difference between the two energy components is observed, showing that the anisotropy of the two...

  3. Studies on spin waves

    International Nuclear Information System (INIS)

    Prets, A.

    1998-07-01

    In the present Ph. D. thesis we are considering a special form of scaling limits, namely the hydrodynamic limit. Such limits are considered to explain macroscopic behavior of matter by means of microscopic dynamic laws. In this procedure a rescaling of space and time plays a central role. The limit will be formulated in a quantum mechanical way. Within this framework we study derivations of the Landau Lifshitz equation for ferromagnets. This equation is a macroscopic equation of motion for the magnetization vector and results into the theory of spin waves. Since we have no exact knowledge of the Heisenberg operator's time evolution no definitive statement an how to regain the Landau Lifshitz equation from the microscopic dynamics can be given. In contrast to the Heisenberg operator, for an Ising type interaction inside a ferromagnet one is able to recover macroscopically a solution of a linearized Landau Lifschitz equation. (author)

  4. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden

    1975-01-01

    The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been...... explained by Liu as originating from the mixing of the spin states of the conduction electrons due to the spin-orbit coupling. We find that this coupling mechanism introduces interactions which violate the selection rules for a simple ferromagnet. The interactions between the magnons and phonons propagating...... in the c direction of Tb have been studied experimentally by means of inelastic neutron scattering. The magnons are coupled to both the acoustic- and optical-transverse phonons. By studying the behavior of the acoustic-optical coupling, we conclude that it is a spin-mixed-induced coupling as proposed...

  5. Spin Waves in Ho2Co17

    DEFF Research Database (Denmark)

    Clausen, Kurt Nørgaard; Lebech, Bente

    1980-01-01

    Spin wave excitations in a single crystal of Ho2Co17 have been studied at 4.8 and 78 K. The results are discussed in terms of a linear spin wave model. At 78 K both ground state and excited state spin waves are observed.......Spin wave excitations in a single crystal of Ho2Co17 have been studied at 4.8 and 78 K. The results are discussed in terms of a linear spin wave model. At 78 K both ground state and excited state spin waves are observed....

  6. Lattice Waves, Spin Waves, and Neutron Scattering

    Science.gov (United States)

    Brockhouse, Bertram N.

    1962-03-01

    Use of neutron inelastic scattering to study the forces between atoms in solids is treated. One-phonon processes and lattice vibrations are discussed, and experiments that verified the existence of the quantum of lattice vibrations, the phonon, are reviewed. Dispersion curves, phonon frequencies and absorption, and models for dispersion calculations are discussed. Experiments on the crystal dynamics of metals are examined. Dispersion curves are presented and analyzed; theory of lattice dynamics is considered; effects of Fermi surfaces on dispersion curves; electron-phonon interactions, electronic structure influence on lattice vibrations, and phonon lifetimes are explored. The dispersion relation of spin waves in crystals and experiments in which dispersion curves for spin waves in Co-Fe alloy and magnons in magnetite were obtained and the reality of the magnon was demonstrated are discussed. (D.C.W)

  7. Spin waves in quantum crystals

    International Nuclear Information System (INIS)

    Kondratenko, P.S.

    1975-01-01

    The paper considers the spectrum of spin waves of a quantum magnetic crystal. It has been assumed that the crystal is characterized by gapless Fermi excitations. The properties of a single-particle Green function for a magnetic crystal are briefly outlined. The dispersion equation system describing the spin wave spectrum has been derived. The spectrum described by the equation system comprises a group of Goldstone modes and a family of spin waves of the zero sound type, associated with the group by an interaction. The maximum number of Goldstone modes in an antiferromagnet is three, whereas in a ferromagnet it is two. At frequencies higher than the characteristic frequencies of magnetic interactions, in an antiferromagnet all three modes have a linear spectrum, whereas in a ferromagnet the longitudinal mode is represented by a linear spectrum and the transverse mode, by a quadratic one. The dynamical susceptibility of a magnetically ordered crystal has been calculated. The thermodynamical potential of the crystal has been proved to vary as a function of the angular crystal orientation in a spin subspace. The results have been obtained by methods of the quantum field theory for the case of zero temperature

  8. Spin waves and spin instabilities in quantum plasmas

    OpenAIRE

    Andreev, P. A.; Kuz'menkov, L. S.

    2014-01-01

    We describe main ideas of method of many-particle quantum hydrodynamics allows to derive equations for description of quantum plasma evolution. We also present definitions of collective quantum variables suitable for quantum plasmas. We show that evolution of magnetic moments (spins) in quantum plasmas leads to several new branches of wave dispersion: spin-electromagnetic plasma waves and self-consistent spin waves. Propagation of neutron beams through quantum plasmas is also considered. Inst...

  9. Excitation of coherent propagating spin waves by pure spin currents.

    Science.gov (United States)

    Demidov, Vladislav E; Urazhdin, Sergei; Liu, Ronghua; Divinskiy, Boris; Telegin, Andrey; Demokritov, Sergej O

    2016-01-28

    Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

  10. Acoustic parametric pumping of spin waves

    Science.gov (United States)

    Keshtgar, Hedyeh; Zareyan, Malek; Bauer, Gerrit E. W.

    2014-11-01

    Recent experiments demonstrated generation of spin currents by ultrasound. We can understand this acoustically induced spin pumping in terms of the coupling between magnetization and lattice waves. Here we study the parametric excitation of magnetization by longitudinal acoustic waves and calculate the acoustic threshold power. The induced magnetization dynamics can be detected by the spin pumping into an adjacent normal metal that displays the inverse spin Hall effect.

  11. Acoustic parametric pumping of spin waves

    OpenAIRE

    Keshtgar, Hedyeh; Zareyan, Malek; Bauer, Gerrit E. W.

    2013-01-01

    Recent experiments demonstrated generation of spin currents by ultrasound. We can understand this acoustically induced spin pumping in terms of the coupling between magnetization and lattice waves. Here we study the parametric excitation of magnetization by longitudinal acoustic waves and calculate the acoustic threshold power. The induced magnetization dynamics can be detected by the spin pumping into an adjacent normal metal that displays the inverse spin Hall effect.

  12. Spin wave spectrum of magnetic nanotubes

    International Nuclear Information System (INIS)

    Gonzalez, A.L.; Landeros, P.; Nunez, Alvaro S.

    2010-01-01

    We investigate the spin wave spectra associated to a vortex domain wall confined within a ferromagnetic nanotube. Basing our study upon a simple model for the energy functional we obtain the dispersion relation, the density of states and dissipation induced life-times of the spin wave excitations in presence of a magnetic domain wall. Our aim is to capture the basics spin wave physics behind the geometrical confinement of nobel magnetic textures.

  13. Spin wave Feynman diagram vertex computation package

    Science.gov (United States)

    Price, Alexander; Javernick, Philip; Datta, Trinanjan

    Spin wave theory is a well-established theoretical technique that can correctly predict the physical behavior of ordered magnetic states. However, computing the effects of an interacting spin wave theory incorporating magnons involve a laborious by hand derivation of Feynman diagram vertices. The process is tedious and time consuming. Hence, to improve productivity and have another means to check the analytical calculations, we have devised a Feynman Diagram Vertex Computation package. In this talk, we will describe our research group's effort to implement a Mathematica based symbolic Feynman diagram vertex computation package that computes spin wave vertices. Utilizing the non-commutative algebra package NCAlgebra as an add-on to Mathematica, symbolic expressions for the Feynman diagram vertices of a Heisenberg quantum antiferromagnet are obtained. Our existing code reproduces the well-known expressions of a nearest neighbor square lattice Heisenberg model. We also discuss the case of a triangular lattice Heisenberg model where non collinear terms contribute to the vertex interactions.

  14. Skyrmion creation and annihilation by spin waves

    International Nuclear Information System (INIS)

    Liu, Yizhou; Yin, Gen; Lake, Roger K.; Zang, Jiadong; Shi, Jing

    2015-01-01

    Single skyrmion creation and annihilation by spin waves in a crossbar geometry are theoretically analyzed. A critical spin-wave frequency is required both for the creation and the annihilation of a skyrmion. The minimum frequencies for creation and annihilation are similar, but the optimum frequency for creation is below the critical frequency for skyrmion annihilation. If a skyrmion already exists in the cross bar region, a spin wave below the critical frequency causes the skyrmion to circulate within the central region. A heat assisted creation process reduces the spin-wave frequency and amplitude required for creating a skyrmion. The effective field resulting from the Dzyaloshinskii-Moriya interaction and the emergent field of the skyrmion acting on the spin wave drive the creation and annihilation processes

  15. Beam Splitter for Spin Waves in Quantum Spin Network

    OpenAIRE

    Yang, S.; Song, Z.; Sun, C. P.

    2005-01-01

    We theoretically design and analytically study a controllable beam splitter for the spin wave propagating in a star-shaped (e.g., a $Y$-shaped beam) spin network. Such a solid state beam splitter can display quantum interference and quantum entanglement by the well-aimed controls of interaction on nodes. It will enable an elementary interferometric device for scalable quantum information processing based on the solid system.

  16. Spin-Wave Wave Function for Quantum Spin Models : Condensed Matter and Statistical Physics

    OpenAIRE

    Franjo, FRANJIC; Sandro, SORELLA; Istituto Nazionale di Fisica della Materia International School for Advance Studies; Istituto Nazionale di Fisica della Materia International School for Advance Studies

    1997-01-01

    We present a new approach to determine an accurate variational wave function for general quantum spin models, completely defined by a consistency requirement with the simple and well-known linear spin-wave expansion. With this wave function, it is also possible to obtain the correct behavior of the long distance correlation functions for the 1D S=1/2 antiferromagnet. In 2D the proposed spin-wave wave function represents an excellent approximation to the exact ground state of the S=1.2 XY mode...

  17. SCATTERING OF SPIN WAVES BY MAGNETIC DEFECTS

    Energy Technology Data Exchange (ETDEWEB)

    Callaway, Joseph

    1962-12-15

    The scattering of spin waves by magnetic point defects is considered using a Green's function method. A partial wave expansion for the scattering amplitude is derived. An expression for the cross section is determined that includes the effect of resonant states. Application is made to the calculation of the thermal conductivity of an insulating ferromagnet. (auth)

  18. 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.

  19. Spin waves theory and applications

    CERN Document Server

    Stancil, Daniel D

    2009-01-01

    Magnetic materials can support propagating waves of magnetization; since these are oscillations in the magneto static properties of the material, they are called magneto static waves (sometimes 'magnons' or 'magnetic polarons'). This book discusses magnetic properties of materials, and magnetic moments of atoms and ions

  20. Unidirectional spin-wave heat conveyer.

    Science.gov (United States)

    An, T; Vasyuchka, V I; Uchida, K; Chumak, A V; Yamaguchi, K; Harii, K; Ohe, J; Jungfleisch, M B; Kajiwara, Y; Adachi, H; Hillebrands, B; Maekawa, S; Saitoh, E

    2013-06-01

    When energy is introduced into a region of matter, it heats up and the local temperature increases. This energy spontaneously diffuses away from the heated region. In general, heat should flow from warmer to cooler regions and it is not possible to externally change the direction of heat conduction. Here we show a magnetically controllable heat flow caused by a spin-wave current. The direction of the flow can be switched by applying a magnetic field. When microwave energy is applied to a region of ferrimagnetic Y3Fe5O12, an end of the magnet far from this region is found to be heated in a controlled manner and a negative temperature gradient towards it is formed. This is due to unidirectional energy transfer by the excitation of spin-wave modes without time-reversal symmetry and to the conversion of spin waves into heat. When a Y3Fe5O12 film with low damping coefficients is used, spin waves are observed to emit heat at the sample end up to 10 mm away from the excitation source. The magnetically controlled remote heating we observe is directly applicable to the fabrication of a heat-flow controller.

  1. Spectrum of spin waves in cold polarized gases

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, T. L., E-mail: phdocandreeva@yandex.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-02-15

    The spin dynamics of cold polarized gases are investigated using the Boltzmann equation. The dispersion relation for spin waves (transverse component of the magnetic moment) and the spin diffusion coefficient of the longitudinal component of the magnetic moment are calculated without using fitting parameters. The spin wave frequency and the diffusion coefficient for rubidium atoms are estimated numerically.

  2. Spin wave scattering and interference in ferromagnetic cross

    Energy Technology Data Exchange (ETDEWEB)

    Nanayakkara, Kasuni; Kozhanov, Alexander [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Center for Nano Optics, Georgia State University, Atlanta, Georgia 30303 (United States); Jacob, Ajey P. [Exploratory Research Device and Integration, GLOBALFOUNDRIES, Albany, New York 12203 (United States)

    2015-10-28

    Magnetostatic spin wave scattering and interference across a CoTaZr ferromagnetic spin wave waveguide cross junction were investigated experimentally and by micromagnetic simulations. It is observed that the phase of the scattered waves is dependent on the wavelength, geometry of the junction, and scattering direction. It is found that destructive and constructive interference of the spin waves generates switching characteristics modulated by the input phase of the spin waves. Micromagnetic simulations are used to analyze experimental data and simulate the spin wave scattering and interference.

  3. Low temperature spin wave dynamics in classical Heisenberg chains

    International Nuclear Information System (INIS)

    Heller, P.; Blume, M.

    1977-11-01

    A detailed and quantitative study of the low-temperature spin-wave dynamics was made for the classical Heisenberg-coupled chain using computer simulation. Results for the spin-wave damping rates and the renormalization of the spin-wave frequencies are presented and compared with existing predictions

  4. Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

    Science.gov (United States)

    Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

    2017-11-01

    The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

  5. Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves

    OpenAIRE

    Hashimoto, Yusuke; Bossini, Davide; Johansen, Tom H.; Saitoh, Eiji; Kirilyuk, Andrei; Rasing, Theo

    2017-01-01

    Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of s...

  6. Spin flip statistics and spin wave interference patterns in Ising ferromagnetic films: A Monte Carlo study.

    Science.gov (United States)

    Acharyya, Muktish

    2017-07-01

    The spin wave interference is studied in two dimensional Ising ferromagnet driven by two coherent spherical magnetic field waves by Monte Carlo simulation. The spin waves are found to propagate and interfere according to the classic rule of interference pattern generated by two point sources. The interference pattern of spin wave is observed in one boundary of the lattice. The interference pattern is detected and studied by spin flip statistics at high and low temperatures. The destructive interference is manifested as the large number of spin flips and vice versa.

  7. Control of Spin Wave Dynamics in Spatially Twisted Magnetic Structures

    Science.gov (United States)

    2017-06-27

    control the spin wave dynamics of magnetic structures twisted spatially, we prepared the exchange-coupled films with the hard magnetic L10-FePt and...information writing of magnetic storage and spintronic applications. Introduction and Objective: Recent rapid progress in the research field of nano...scaled bilayer elements is also an important aim of this project. Approach/Method: The exchange-coupled films with the hard magnetic L10-FePt and

  8. Demonstration of a robust magnonic spin wave interferometer.

    Science.gov (United States)

    Kanazawa, Naoki; Goto, Taichi; Sekiguchi, Koji; Granovsky, Alexander B; Ross, Caroline A; Takagi, Hiroyuki; Nakamura, Yuichi; Inoue, Mitsuteru

    2016-07-22

    Magnonics is an emerging field dealing with ultralow power consumption logic circuits, in which the flow of spin waves, rather than electric charges, transmits and processes information. Waves, including spin waves, excel at encoding information via their phase using interference. This enables a number of inputs to be processed in one device, which offers the promise of multi-input multi-output logic gates. To realize such an integrated device, it is essential to demonstrate spin wave interferometers using spatially isotropic spin waves with high operational stability. However, spin wave reflection at the waveguide edge has previously limited the stability of interfering waves, precluding the use of isotropic spin waves, i.e., forward volume waves. Here, a spin wave absorber is demonstrated comprising a yttrium iron garnet waveguide partially covered by gold. This device is shown experimentally to be a robust spin wave interferometer using the forward volume mode, with a large ON/OFF isolation value of 13.7 dB even in magnetic fields over 30 Oe.

  9. Position dependent spin wave spectrum in nanostrip magnonic waveguides

    International Nuclear Information System (INIS)

    Wang, Qi; Zhang, Huaiwu; Ma, Guokun; Liao, Yulong; Zhong, Zhiyong; Zheng, Yun

    2014-01-01

    The dispersion curves of propagating spin wave along different positions in nanostrip magnonic waveguides were studied by micromagnetic simulation. The results show that the modes of spin wave in the nanostrip magnonic waveguide are dependent on the position and the weak even modes of spin wave are excited even by symmetric excitation fields in a nanostrip magnonic waveguide. The reasons of the position dependent dispersion curve are explained by associating with geometrical confinement in the nanostrip magnonic waveguide

  10. Light-front wave function of composite system with spin

    International Nuclear Information System (INIS)

    Karmanov, V.A.

    1979-01-01

    The method to construct the relativistic wave function with spin on the light front is developed. The spin structure of the deuteron wave function in relativistic range is found. The calculation methods are illustrated by the calculation of elastic pd-scattering cross section. The consideration carried out is equivalent to the solution of the problem of taking into account the spins and angular momenta in the parton wave functions in the infinite momentum frame

  11. A switchable spin-wave signal splitter for magnonic networks

    Science.gov (United States)

    Heussner, F.; Serga, A. A.; Brächer, T.; Hillebrands, B.; Pirro, P.

    2017-09-01

    The influence of an inhomogeneous magnetization distribution on the propagation of caustic-like spin-wave beams in unpatterned magnetic films has been investigated by utilizing micromagnetic simulations. Our study reveals a locally controllable and reconfigurable tractability of the beam directions. This feature is used to design a device combining split and switch functionalities for spin-wave signals on the micrometer scale. A coherent transmission of spin-wave signals through the device is verified. This attests the applicability in magnonic networks where the information is encoded in the phase of the spin waves.

  12. Nonlinear spin wave coupling in adjacent magnonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2016-07-25

    We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

  13. Information processing in patterned magnetic nanostructures with edge spin waves.

    Science.gov (United States)

    Lara, Antonio; Robledo Moreno, Javier; Guslienko, Konstantin Y; Aliev, Farkhad G

    2017-07-17

    Low dissipation data processing with spins is one of the promising directions for future information and communication technologies. Despite a significant progress, the available magnonic devices are not broadband yet and have restricted capabilities to redirect spin waves. Here we propose a breakthrough approach to spin wave manipulation in patterned magnetic nanostructures with unmatched characteristics, which exploits a spin wave analogue to edge waves propagating along a water-wall boundary. Using theory, micromagnetic simulations and experiment we investigate spin waves propagating along the edges in magnetic structures, under an in-plane DC magnetic field inclined with respect to the edge. The proposed edge spin waves overcome important challenges faced by previous technologies such as the manipulation of the spin wave propagation direction, and they substantially improve the capability of transmitting information at frequencies exceeding 10 GHz. The concept of the edge spin waves allows to design a broad of logic devices such as splitters, interferometers, or edge spin wave transistors with unprecedented characteristics and a potentially strong impact on information technologies.

  14. Nonlinear spin wave coupling in adjacent magnonic crystals

    International Nuclear Information System (INIS)

    Sadovnikov, A. V.; Nikitov, S. A.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E.

    2016-01-01

    We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

  15. Stimulated polarization wave process in spin 3/2 chains

    International Nuclear Information System (INIS)

    Furman, G. B.

    2007-01-01

    Stimulated wave of polarization, triggered by a flip of a single spin, presents a simple model of quantum amplification. Recently, it has been demonstrated that, in an idealized one-dimensional Ising spin 1/2 chain with nearest-neighbor interactions and realistic spin 1/2 chain including the natural dipole-dipole interactions, irradiated by a weak resonant transverse field, a wave of flipped spins can be triggered by a single spin flip. Here we focuse on control of polarization wave in chain of spin 3/2, where the nuclear quadrupole interaction is dominant. Results of simulations for 1D spin chains and rings with up to five spins are presented.

  16. Spin-wave wavelength down-conversion at thickness steps

    Science.gov (United States)

    Stigloher, Johannes; Taniguchi, Takuya; Madami, Marco; Decker, Martin; Körner, Helmut S.; Moriyama, Takahiro; Gubbiotti, Gianluca; Ono, Teruo; Back, Christian H.

    2018-05-01

    We report a systematic experimental study on the refraction and reflection of magnetostatic spin-waves at a thickness step between two Permalloy films of different thickness. The transmitted spin-waves for the transition from a thick film to a thin film have a higher wave vector compared to the incoming waves. Consequently, such systems may find use as passive wavelength transformers in magnonic networks. We investigate the spin-wave transmission behavior by studying the influence of the external magnetic field, incident angle, and thickness ratio of the films using time-resolved scanning Kerr microscopy and micro-focused Brillouin light scattering.

  17. Spin-wave logic devices based on isotropic forward volume magnetostatic waves

    International Nuclear Information System (INIS)

    Klingler, S.; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V.

    2015-01-01

    We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves

  18. Spin-wave logic devices based on isotropic forward volume magnetostatic waves

    Energy Technology Data Exchange (ETDEWEB)

    Klingler, S., E-mail: stefan.klingler@wmi.badw-muenchen.de; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

    2015-05-25

    We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves.

  19. Spin Waves in a Classical Compressible Heisenberg Chain

    NARCIS (Netherlands)

    Fivez, J.; Raedt, H. De

    1980-01-01

    The effect of the spin—lattice interaction on the spin dynamics of a classical Heisenberg chain is studied by means of a truncated continued fraction. At low temperature, the spin correlation length and the spin wave frequency show the same simple dependence on the coupling.

  20. SU (N ) spin-wave theory: Application to spin-orbital Mott insulators

    Science.gov (United States)

    Dong, Zhao-Yang; Wang, Wei; Li, Jian-Xin

    2018-05-01

    We present the application of the SU (N ) spin-wave theory to spin-orbital Mott insulators whose ground states exhibit magnetic orders. When taking both spin and orbital degrees of freedom into account rather than projecting Hilbert space onto the Kramers doublet, which is the lowest spin-orbital locked energy levels, the SU (N ) spin-wave theory should take the place of the SU (2 ) one due to the inevitable spin-orbital multipole exchange interactions. To implement the application, we introduce an efficient general local mean-field method, which involves all local fluctuations, and develop the SU (N ) linear spin-wave theory. Our approach is tested firstly by calculating the multipolar spin-wave spectra of the SU (4 ) antiferromagnetic model. Then, we apply it to spin-orbital Mott insulators. It is revealed that the Hund's coupling would influence the effectiveness of the isospin-1 /2 picture when the spin-orbital coupling is not large enough. We further carry out the SU (N ) spin-wave calculations of two materials, α -RuCl3 and Sr2IrO4 , and find that the magnonic and spin-orbital excitations are consistent with experiments.

  1. Theory of Spin Waves in Strongly Anisotropic Magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Cooke, J. F.

    1976-01-01

    A new infinite-order perturbation approach to the theory of spin waves in strongly anisotropic magnets is introduced. The system is transformed into one with effective two-ion anisotropy and considerably reduced ground-state corrections. A general expression for the spin-wave energy, valid to any...

  2. Bifurcation of the spin-wave equations

    International Nuclear Information System (INIS)

    Cascon, A.; Koiller, J.; Rezende, S.M.

    1990-01-01

    We study the bifurcations of the spin-wave equations that describe the parametric pumping of collective modes in magnetic media. Mechanisms describing the following dynamical phenomena are proposed: (i) sequential excitation of modes via zero eigenvalue bifurcations; (ii) Hopf bifurcations followed (or not) by Feingenbaum cascades of period doubling; (iii) local and global homoclinic phenomena. Two new organizing center for routes to chaos are identified; in the classification given by Guckenheimer and Holmes [GH], one is a codimension-two local bifurcation, with one pair of imaginary eigenvalues and a zero eigenvalue, to which many dynamical consequences are known; secondly, global homoclinic bifurcations associated to splitting of separatrices, in the limit where the system can be considered a Hamiltonian subjected to weak dissipation and forcing. We outline what further numerical and algebraic work is necessary for the detailed study following this program. (author)

  3. Spin wave absorber generated by artificial surface anisotropy for spin wave device network

    Directory of Open Access Journals (Sweden)

    Naoki Kanazawa

    2016-09-01

    Full Text Available Spin waves (SWs have the potential to reduce the electric energy loss in signal processing networks. The SWs called magnetostatic forward volume waves (MSFVWs are advantageous for networking due to their isotropic dispersion in the plane of a device. To control the MSFVW flow in a processing network based on yttrium iron garnet, we developed a SW absorber using artificial structures. The mechanical surface polishing method presented in this work can well control extrinsic damping without changing the SW dispersion of the host material. Furthermore, enhancement of the ferromagnetic resonance linewidth over 3 Oe was demonstrated.

  4. Spin wave vortex from the scattering on Bloch point solitons

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho-Santos, V.L., E-mail: vagson.carvalho@usach.cl [Instituto Federal de Educação, Ciência e Tecnologia Baiano - Campus Senhor do Bonfim, Km 04 Estrada da Igara, 48970-000 Senhor do Bonfim, Bahia (Brazil); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Elías, R.G., E-mail: gabriel.elias@usach.cl [Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, A.S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile)

    2015-12-15

    The interaction of a spin wave with a stationary Bloch point is studied. The topological non-trivial structure of the Bloch point manifests in the propagation of spin waves endowing them with a gauge potential that resembles the one associated with the interaction of a magnetic monopole and an electron. By pursuing this analogy, we are led to the conclusion that the scattering of spin waves and Bloch points is accompanied by the creation of a magnon vortex. Interference between such a vortex and a plane wave leads to dislocations in the interference pattern that can be measurable by means of magnon holography.

  5. Spin-wave damping in ferromagnets in the ordered regime

    International Nuclear Information System (INIS)

    Reinecke, T.L.; Stinchcombe, R.B.

    1978-01-01

    Theoretical results based on a high-density approach are compared with experimental measurements for the damping of long-wavelength spin waves in the nearly isotropic ferromagnet for temperatures up to the critical regime. The theory, which has no adjustable parameters, is shown to account well for the overall magnitude of the spin-wave widths measured in recent neutron scattering experiments on EuO, and it is also in satisfactory agreement with the measured wave vector and temperature dependence of these widths. An estimate is also given for the contribution of dipolar coupling to the spin-wave widths

  6. RESEARCH PLAN FOR SPIN PHYSICS AT RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    AIDALA, C.; BUNCE, G.; ET AL.

    2005-02-01

    In this report we present the research plan for the RHIC spin program. The report covers (1) the science of the RHIC spin program in a world-wide context; (2) the collider performance requirements for the RHIC spin program; (3) the detector upgrades required, including timelines; (4) time evolution of the spin program.

  7. Perspectives of using spin waves for computing and signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Csaba, György, E-mail: gcsaba@gmail.com [Center for Nano Science and Technology, University of Notre Dame (United States); Faculty for Information Technology and Bionics, Pázmány Péter Catholic University (Hungary); Papp, Ádám [Center for Nano Science and Technology, University of Notre Dame (United States); Faculty for Information Technology and Bionics, Pázmány Péter Catholic University (Hungary); Porod, Wolfgang [Center for Nano Science and Technology, University of Notre Dame (United States)

    2017-05-03

    Highlights: • We give an overview of spin wave-based computing with emphasis on non-Boolean signal processors. • Spin waves can combine the best of electronics and photonics and do it in an on-chip and integrable way. • Copying successful approaches from microelectronics may not be the best way toward spin-wave based computing. • Practical devices can be constructed by minimizing the number of required magneto-electric interconnections. - Abstract: Almost all the world's information is processed and transmitted by either electric currents or photons. Now they may get a serious contender: spin-wave-based devices may just perform some information-processing tasks in a lot more efficient and practical way. In this article, we give an engineering perspective of the potential of spin-wave-based devices. After reviewing various flavors for spin-wave-based processing devices, we argue that the niche for spin-wave-based devices is low-power, compact and high-speed signal-processing devices, where most traditional electronics show poor performance.

  8. Tunable spin waves in diluted magnetic semiconductor nanoribbon

    Science.gov (United States)

    Lyu, Pin; Zhang, Jun-Yi

    2018-01-01

    The spin wave excitation spectrum in diluted magnetic semiconductor (DMS) nanoribbons was calculated by taking account of the quantum confinement effect of carriers and spin waves. By introducing the boundary condition for the spin waves, we derived the spin wave dispersion using the path-integral formulation and Green's function method. It was shown that the spin wave excitation spectrum is discrete due to the confinement effect and strongly dependent on the carrier density, the magnetic ion density, and the width of the nanoribbon. When the width of the nanoribbon is beyond the typical nanoscales, the size effect on the excitation energies of the spin waves disappears in our calculation, which is in qualitative agreement with no obvious size effect observed in the as-made nanodevices of (Ga,Mn)As in this size regime. Our results provide a potential way to control the spin waves in the DMS nanoribbon not only by the carrier density and the magnetic ion density but also by the nanostructure geometry.

  9. Spin effect on parametric interactions of waves in magnetoplasmas

    International Nuclear Information System (INIS)

    Shahid, M.; Melrose, D. B.; Jamil, M.; Murtaza, G.

    2012-01-01

    The parametric decay instability of upper hybrid wave into low-frequency electromagnetic Shear Alfvén wave and Ordinary mode radiation (O-mode) has been investigated in an electron-ion plasma immersed in the uniform external magnetic field. Incorporating quantum effect due to electron spin, the fluid model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling in a magnetoplasma. It is shown that the spin of electrons has considerable effect on the parametric decay of upper hybrid wave into Ordinary mode radiation (O-mode) and Shear Alfvén wave even in classical regime.

  10. 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 Hamilton......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...

  11. Gravitational waves from spinning eccentric binaries

    Science.gov (United States)

    Csizmadia, Péter; Debreczeni, Gergely; Rácz, István; Vasúth, Mátyás

    2012-12-01

    This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations, while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems, it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity, thus confirming a similar result obtained by Brown and Zimmerman (2010 Phys. Rev. D 81 024007). In addition, by investigating the validity of the energy balance relation we show that, contrary to the general expectations, the PN approximation should not be applied once the PN parameter gets beyond the critical value ˜0.08 - 0.1. Finally, by studying the early phase of the gravitational waves emitted by strongly eccentric binary systems—which could be formed e.g. in various many-body interactions in the galactic halo—we have found that they possess very specific characteristics which may be used to identify these type of binary systems. This paper is dedicated to the memory of our colleague and friend Péter Csizmadia a young physicist, computer expert and one of the best Hungarian mountaineers who disappeared in China’s Sichuan near the Ren Zhong Feng peak of the Himalayas on 23 Oct. 2009. We started to develop CBwaves jointly with Péter a couple of months before he left for China.

  12. Frequency selective tunable spin wave channeling in the magnonic network

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Odincov, S. A.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Stognij, A. I. [Scientific-Practical Materials Research Center, National Academy of Sciences of Belarus, 220072 Minsk (Belarus)

    2016-04-25

    Using the space-resolved Brillouin light scattering spectroscopy, we study the frequency and wavenumber selective spin-wave channeling. We demonstrate the frequency selective collimation of spin-wave in an array of magnonic waveguides, formed between the adjacent magnonic crystals on the surface of yttrium iron garnet film. We show the control over spin-wave propagation length by the orientation of an in-plane bias magnetic field. Fabricated array of magnonic crystal can be used as a magnonic platform for multidirectional frequency selective signal processing applications in magnonic networks.

  13. Scattering of spinning test particles by gravitational plane waves

    International Nuclear Information System (INIS)

    Bini, D.; Gemelli, G.

    1997-01-01

    The authors study the motion of spinning particles in the gravitational plane-wave background and discuss particular solutions under a suitable choice of supplementary conditions. An analysis of the discontinuity of the motion across the wavefront is presented too

  14. Spin waves and the order-disorder transition in chromium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.

    1969-01-01

    The inelastic magnetic scattering of neutrons has been studied in Cr and Cr0.95-Mn0.05 both below and above the Neel temperature. The temperature dependence of the spin-wave velocity in the alloy has been measured below TN. The scattering above TN may also be interpreted in terms of spin-wavelike...

  15. Gravitational Waves and the Maximum Spin Frequency of Neutron Stars

    NARCIS (Netherlands)

    Patruno, A.; Haskell, B.; D'Angelo, C.

    2012-01-01

    In this paper, we re-examine the idea that gravitational waves are required as a braking mechanism to explain the observed maximum spin frequency of neutron stars. We show that for millisecond X-ray pulsars, the existence of spin equilibrium as set by the disk/magnetosphere interaction is sufficient

  16. Magnetic domain walls as reconfigurable spin-wave nano-channels

    Science.gov (United States)

    Wagner, Kai

    Research efforts to utilize spin waves as information carriers for wave based logic in micro- and nano-structured ferromagnetic materials have increased tremendously over the recent years. However, finding efficient means of tailoring and downscaling guided spin-wave propagation in two dimensions, while maintaining energy efficiency and reconfigurability, still remains a delicate challenge. Here we target these challenges by spin-wave transport inside nanometer-scaled potential wells formed along magnetic domain walls. For this, we investigate the magnetization dynamics of a rectangular-like element in a Landau state exhibiting a so called 180° Néel wall along its center. By microwave antennae the rf-excitation is constricted to one end of the domain wall and the spin-wave intensities are recorded by means of Brillouin-Light Scattering microscopy revealing channeled transport. Additional micromagnetic simulations with pulsed as well as cw-excitation are performed to yield further insight into this class of modes. We find several spin-wave modes quantized along the width of the domain wall yet with well defined wave vectors along the wall, exhibiting positive dispersion. In a final step, we demonstrate the flexibility of these spin-wave nano-channels based on domain walls. In contrast to wave guides realised by fixed geometries, domain walls can be easily manipulated. Here we utilize small external fields to control its position with nanometer precision over a micrometer range, while still enabling transport. Domain walls thus, open the perspective for reprogrammable and yet non-volatile spin-wave waveguides of nanometer width. Financial support by the Deutsche Forschungsgemeinschaft within project SCHU2922/1-1 is gratefully acknowledged.

  17. Spin wave spectrum and zero spin fluctuation of antiferromagnetic solid 3He

    International Nuclear Information System (INIS)

    Roger, M.; Delrieu, J.M.

    1981-08-01

    The spin wave spectrum and eigenvectors of the uudd antiferromagnetic phase of solid 3 He are calculated; an optical mode is predicted around 150 - 180 Mc and a zero point spin deviation of 0.74 is obtained in agreement with the antiferromagnetic resonance frequency measured by Osheroff

  18. Magnetohydrodynamic spin waves in degenerate electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mushtaq, A. [TPPD, PINSTECH Nilore, 44000 Islamabad (Pakistan); National Center for Physics, Shahdrah Valley Road, 44000 Islamabad (Pakistan); Maroof, R.; Ahmad, Zulfiaqr [Institute of Physics and Electronics, University of Peshawar, 25000 Peshawar (Pakistan); Qamar, A. [National Center for Physics, Shahdrah Valley Road, 44000 Islamabad (Pakistan); Institute of Physics and Electronics, University of Peshawar, 25000 Peshawar (Pakistan)

    2012-05-15

    Low frequency magnetosonic waves are studied in magnetized degenerate electron-positron-ion plasmas with spin effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, and spin magnetization energy, a generalized dispersion relation for oblique magnetosonic waves is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. For three different values of angle {theta}, the generalized dispersion relation is reduced to three different relations under the low frequency magnetohydrodynamic assumptions. It is found that the effect of quantum corrections in the presence of positron concentration significantly modifies the dispersive properties of these modes. The importance of the work relevant to compact astrophysical bodies is pointed out.

  19. Bandwidth broadening and asymmetric softening of collective spin waves in magnonic crystals

    International Nuclear Information System (INIS)

    Montoncello, F.; Giovannini, L.

    2014-01-01

    We investigate the dependence on the applied field of the frequency/wavevector dispersion relations of collective spin waves in arrays of dots, close to a magnetic transition. In particular, we focus on the low frequency “soft” modes in three different cases: end modes in the transition between two different saturated states in ellipses, fundamental mode in the saturated-to-vortex transition in disks, and gyrotropic mode in the vortex-to-saturated transition in disks. Noteworthy, the spin waves with nonzero Bloch wavevector along the direction of the applied field happen to soften earlier than spin waves with a Bloch wavevector along different directions, and this feature is responsible for an asymmetric broadening of the bandwidth along the different lattice directions. This is particularly useful in magnonic/spin-logic device research, if different binary digits are associated to modes with the same cell function but different propagation directions.

  20. Spin precession and spin waves in a chiral electron gas: Beyond Larmor's theorem

    Science.gov (United States)

    Karimi, Shahrzad; Baboux, Florent; Perez, Florent; Ullrich, Carsten A.; Karczewski, Grzegorz; Wojtowicz, Tomasz

    2017-07-01

    Larmor's theorem holds for magnetic systems that are invariant under spin rotation. In the presence of spin-orbit coupling this invariance is lost and Larmor's theorem is broken: for systems of interacting electrons, this gives rise to a subtle interplay between the spin-orbit coupling acting on individual single-particle states and Coulomb many-body effects. We consider a quasi-two-dimensional, partially spin-polarized electron gas in a semiconductor quantum well in the presence of Rashba and Dresselhaus spin-orbit coupling. Using a linear-response approach based on time-dependent density-functional theory, we calculate the dispersions of spin-flip waves. We obtain analytic results for small wave vectors and up to second order in the Rashba and Dresselhaus coupling strengths α and β . Comparison with experimental data from inelastic light scattering allows us to extract α and β as well as the spin-wave stiffness very accurately. We find significant deviations from the local density approximation for spin-dependent electron systems.

  1. Magnetization oscillations and waves driven by pure spin currents

    Energy Technology Data Exchange (ETDEWEB)

    Demidov, V.E. [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, Corrensstrasse 2-4, 48149 Muenster (Germany); Urazhdin, S. [Department of Physics, Emory University, Atlanta, GA 30322 (United States); Loubens, G. de [SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Klein, O. [INAC-SPINTEC, CEA/CNRS and Univ. Grenoble Alpes, 38000 Grenoble (France); Cros, V.; Anane, A. [Unité Mixte de Physique CNRS, Thales, Univ. Paris Sud, Université Paris-Saclay, 91767 Palaiseau (France); Demokritov, S.O., E-mail: demokrit@uni-muenster.de [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, Corrensstrasse 2-4, 48149 Muenster (Germany); Institute of Metal Physics, Ural Division of RAS, Yekaterinburg 620041 (Russian Federation)

    2017-02-23

    Recent advances in the studies of pure spin currents–flows of angular momentum (spin) not accompanied by the electric currents–have opened new horizons for the emerging technologies based on the electron’s spin degree of freedom, such as spintronics and magnonics. The main advantage of pure spin current, as compared to the spin-polarized electric current, is the possibility to exert spin transfer torque on the magnetization in thin magnetic films without the electrical current flow through the material. In addition to minimizing Joule heating and electromigration effects, this enables the implementation of spin torque devices based on the low-loss insulating magnetic materials, and offers an unprecedented geometric flexibility. Here we review the recent experimental achievements in investigations of magnetization oscillations excited by pure spin currents in different nanomagnetic systems based on metallic and insulating magnetic materials. We discuss the spectral properties of spin-current nano-oscillators, and relate them to the spatial characteristics of the excited dynamic magnetic modes determined by the spatially-resolved measurements. We also show that these systems support locking of the oscillations to external microwave signals, as well as their mutual synchronization, and can be used as efficient nanoscale sources of propagating spin waves.

  2. Spin waves propagation and confinement in magnetic microstructures

    International Nuclear Information System (INIS)

    Bailleul, Matthieu

    2002-01-01

    In this thesis, ferromagnetic thin film elements have been studied on a small scale (μm) and at high frequencies (GHz). For those studies, a microwave spectrometer based on the use of micro-antennae has been developed. It had been applied to two different systems. In a first time, we have launched and detected spin waves in continuous films. This allowed us to describe both the transduction process and the relaxation law for long wavelength spin waves. In a second time, we have studied micrometer-wide stripe for which the magnetic ground state is inhomogeneous. The obtained microwave response has been interpreted in terms of micro-magnetic phase transitions and in terms of spin waves confinement. (author)

  3. Tunable Snell's law for spin waves in heterochiral magnetic films

    Science.gov (United States)

    Mulkers, Jeroen; Van Waeyenberge, Bartel; Milošević, Milorad V.

    2018-03-01

    Thin ferromagnetic films with an interfacially induced DMI exhibit nontrivial asymmetric dispersion relations that lead to unique and useful magnonic properties. Here we derive an analytical expression for the magnon propagation angle within the micromagnetic framework and show how the dispersion relation can be approximated with a comprehensible geometrical interpretation in the k space of the propagation of spin waves. We further explore the refraction of spin waves at DMI interfaces in heterochiral magnetic films, after deriving a generalized Snell's law tunable by an in-plane magnetic field, that yields analytical expressions for critical incident angles. The found asymmetric Brewster angles at interfaces of regions with different DMI strengths, adjustable by magnetic field, support the conclusion that heterochiral ferromagnetic structures are an ideal platform for versatile spin-wave guides.

  4. Spin-wave utilization in a quantum computer

    Science.gov (United States)

    Khitun, A.; Ostroumov, R.; Wang, K. L.

    2001-12-01

    We propose a quantum computer scheme using spin waves for quantum-information exchange. We demonstrate that spin waves in the antiferromagnetic layer grown on silicon may be used to perform single-qubit unitary transformations together with two-qubit operations during the cycle of computation. The most attractive feature of the proposed scheme is the possibility of random access to any qubit and, consequently, the ability to recognize two qubit gates between any two distant qubits. Also, spin waves allow us to eliminate the use of a strong external magnetic field and microwave pulses. By estimate, the proposed scheme has as high as 104 ratio between quantum system coherence time and the time of a single computational step.

  5. Spin Wave Theory of Strongly Anisotropic Magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A strong anisotropy gives rise to a non-spherical precession of the spins with different amplitudes in the x and y directions. The highly anharmonic exchange interaction thereby becomes effectively anisotropic. The possibility of detecting a genuine two-ion anisotropy is discussed, and comments...

  6. Nonlinear dynamics and chaotic behaviour of spin wave instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Rezende, S M; Aguiar, F.M. de.

    1986-09-01

    Recent experiments revealed that spin wave instabilities driven by microwave fields, either parallel or transverse to the static magnetic field, display chaotic dynamics similar to other physical systems. A theory based on the coupled nonlinear equations of motion for two spin wave modes is presented which explains most features of the experimental observations. The model predicts subharmonic routes to chaos that depend on the parameter values. For certain parameters the system exhibits a Feigenbaum scenario characteristic of one-dimensional maps. Other parameters lead to different subharmonic routes indicative of multidimensional behavior, as observed in some experiments.

  7. Four-wave neutron-resonance spin echo

    International Nuclear Information System (INIS)

    Grigoriev, S.V.; Kraan, W.H.; Rekveldt, M.Th.

    2004-01-01

    We develop a technique of scattering from many-body systems. It is based on the principle of the neutron spin echo (SE), where a neutron wave in the magnetic field splits into two waves, which are separated in space or in time after propagation in this field. The neutron thus prepared as a probe passes through the sample to test its properties on a space R or time t scale. This separation in space or in time can be measured using coherence of these two waves as a phase shift φ between them. These two waves are collected or focused and compensated by the SE technique in order to compare their phases after interaction with the sample. In this way one studies interference between these waves and thus can directly measure the pair-correlation function in space or in time. Instead of two-wave SE we propose to realize the four-wave neutron-resonance spin-echo (NRSE). In our experiments, spin precession produced by a couple of the neutron-resonance coils in one arm is compensated by an identical couple of other NR coils in a second arm of a spin-echo machine. The neutron spin-flip probability ρ in the resonance coils is a key parameter of the NRSE arm. The limiting cases, ρ=0 and ρ=1, provide, in quantum terms, a two-level-two-wave k splitting of the neutron and result in the separation of the split waves into two different lengths in space (R 1 ,R 2 ) or in time (t 1 ,t 2 ). These two cases correspond to Larmor precession with phase φ 1 in the static magnetic fields of the NR flippers or to NRSE precession with φ 2 , respectively. The intermediate case, 0 1 ,R 2 ,R 3 ) or in time (t 1 ,t 2 ,t 3 ). The interference of each pair of waves after compensation results in three different echos with phases φ 1 , φ 2 , and φ 3 =(φ 1 +φ 2 )/2. Focusing or compensating all four waves into a single point of the phase-of-waves diagram produces quantum interference of all newly created waves. This task of focusing is experimentally performed. Different options for the

  8. Control phase shift of spin-wave by spin-polarized current and its application in logic gates

    International Nuclear Information System (INIS)

    Chen, Xiangxu; Wang, Qi; Liao, Yulong; Tang, Xiaoli; Zhang, Huaiwu; Zhong, Zhiyong

    2015-01-01

    We proposed a new ways to control the phase shift of propagating spin waves by applying a local spin-polarized current on ferromagnetic stripe. Micromagnetic simulation showed that a phase shift of about π can be obtained by designing appropriate width and number of pinned magnetic layers. The ways can be adopted in a Mach-Zehnder-type interferometer structure to fulfill logic NOT gates based on spin waves. - Highlights: • Spin-wave phase shift can be controlled by a local spin-polarized current. • Spin-wave phase shift increased with the increasing of current density. • Spin-wave phase shift can reach about 0.3π at a particular current density. • The ways can be used in a Mach-Zehnder-type interferometer to fulfill logic gates

  9. Spin-wave interference patterns created by spin-torque nano-oscillators for memory and computation

    International Nuclear Information System (INIS)

    Macia, Ferran; Kent, Andrew D; Hoppensteadt, Frank C

    2011-01-01

    Magnetization dynamics in nanomagnets has attracted broad interest since it was predicted that a dc current flowing through a thin magnetic layer can create spin-wave excitations. These excitations are due to spin momentum transfer, a transfer of spin angular momentum between conduction electrons and the background magnetization, that enables new types of information processing. Here we show how arrays of spin-torque nano-oscillators can create propagating spin-wave interference patterns of use for memory and computation. Memristic transponders distributed on the thin film respond to threshold tunnel magnetoresistance values, thereby allowing spin-wave detection and creating new excitation patterns. We show how groups of transponders create resonant (reverberating) spin-wave interference patterns that may be used for polychronous wave computation and information storage.

  10. Statistical mechanics of magnetic excitations from spin waves to stripes and checkerboards

    CERN Document Server

    Rastelli, Enrico

    2013-01-01

    The aim of this advanced textbook is to provide the reader with a comprehensive explanation of the ground state configurations, the spin wave excitations and the equilibrium properties of spin lattices described by the Ising-Heisenberg Hamiltonians in the presence of short (exchange) and long range (dipole) interactions.The arguments are presented in such detail so as to enable advanced undergraduate and graduate students to cross the threshold of active research in magnetism by using both analytic calculations and Monte Carlo simulations.Recent results about unorthodox spin configurations suc

  11. Micromagnetic computer simulations of spin waves in nanometre-scale patterned magnetic elements

    International Nuclear Information System (INIS)

    Kim, Sang-Koog

    2010-01-01

    Current needs for further advances in the nanotechnologies of information-storage and -processing devices have attracted a great deal of interest in spin (magnetization) dynamics in nanometre-scale patterned magnetic elements. For instance, the unique dynamic characteristics of non-uniform magnetic microstructures such as various types of domain walls, magnetic vortices and antivortices, as well as spin wave dynamics in laterally restricted thin-film geometries, have been at the centre of extensive and intensive researches. Understanding the fundamentals of their unique spin structure as well as their robust and novel dynamic properties allows us to implement new functionalities into existing or future devices. Although experimental tools and theoretical approaches are effective means of understanding the fundamentals of spin dynamics and of gaining new insights into them, the limitations of those same tools and approaches have left gaps of unresolved questions in the pertinent physics. As an alternative, however, micromagnetic modelling and numerical simulation has recently emerged as a powerful tool for the study of a variety of phenomena related to spin dynamics of nanometre-scale magnetic elements. In this review paper, I summarize the recent results of simulations of the excitation and propagation and other novel wave characteristics of spin waves, highlighting how the micromagnetic computer simulation approach contributes to an understanding of spin dynamics of nanomagnetism and considering some of the merits of numerical simulation studies. Many examples of micromagnetic modelling for numerical calculations, employing various dimensions and shapes of patterned magnetic elements, are given. The current limitations of continuum micromagnetic modelling and of simulations based on the Landau-Lifshitz-Gilbert equation of motion of magnetization are also discussed, along with further research directions for spin-wave studies.

  12. Micromagnetic computer simulations of spin waves in nanometre-scale patterned magnetic elements

    Science.gov (United States)

    Kim, Sang-Koog

    2010-07-01

    Current needs for further advances in the nanotechnologies of information-storage and -processing devices have attracted a great deal of interest in spin (magnetization) dynamics in nanometre-scale patterned magnetic elements. For instance, the unique dynamic characteristics of non-uniform magnetic microstructures such as various types of domain walls, magnetic vortices and antivortices, as well as spin wave dynamics in laterally restricted thin-film geometries, have been at the centre of extensive and intensive researches. Understanding the fundamentals of their unique spin structure as well as their robust and novel dynamic properties allows us to implement new functionalities into existing or future devices. Although experimental tools and theoretical approaches are effective means of understanding the fundamentals of spin dynamics and of gaining new insights into them, the limitations of those same tools and approaches have left gaps of unresolved questions in the pertinent physics. As an alternative, however, micromagnetic modelling and numerical simulation has recently emerged as a powerful tool for the study of a variety of phenomena related to spin dynamics of nanometre-scale magnetic elements. In this review paper, I summarize the recent results of simulations of the excitation and propagation and other novel wave characteristics of spin waves, highlighting how the micromagnetic computer simulation approach contributes to an understanding of spin dynamics of nanomagnetism and considering some of the merits of numerical simulation studies. Many examples of micromagnetic modelling for numerical calculations, employing various dimensions and shapes of patterned magnetic elements, are given. The current limitations of continuum micromagnetic modelling and of simulations based on the Landau-Lifshitz-Gilbert equation of motion of magnetization are also discussed, along with further research directions for spin-wave studies.

  13. Coherence and stiffness of spin waves in diluted ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Turek, Ilja; Kudrnovský, Josef; Drchal, Václav

    2016-01-01

    Roč. 94, č. 17 (2016), č. článku 174447. ISSN 2469-9950 R&D Projects: GA ČR GA15-13436S Institutional support: RVO:68081723 ; RVO:68378271 Keywords : spin wave s * diluted ferromagnets * disordered systems Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.836, year: 2016

  14. Spin-wave and critical neutron scattering from chromium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Axe, J.D.; Shirane, G.

    1971-01-01

    Chromium and its dilute alloys are unique examples of magnetism caused by itinerant electrons. The magnetic excitations have been studied by inelastic neutron scattering using a high-resolution triple-axis spectrometer. Spin-wave peaks in q scans at constant energy transfer ℏω could, in general...

  15. Spin waves in two-dimensional ferromagnet with large easy-plane anisotropy

    International Nuclear Information System (INIS)

    Fridman, Yu.A.; Spirin, D.V.

    2002-01-01

    Spin waves in easy-plane two-dimensional ferromagnet when anisotropy is much stronger than exchange are investigated. The spectra of magnons, the spin-spin and quadrupolar correlation functions have been derived. It is shown that in such a system there exist spin waves at low temperatures. Some properties of the quadrupolar ordering in ferromagnets are discussed

  16. Spin Wave Theory in Two-Dimensional Coupled Antiferromagnets

    Science.gov (United States)

    Shimahara, Hiroshi

    2018-04-01

    We apply spin wave theory to two-dimensional coupled antiferromagnets. In particular, we primarily examine a system that consists of small spins coupled by a strong exchange interaction J1, large spins coupled by a weak exchange interaction J2, and an anisotropic exchange interaction J12 between the small and large spins. This system is an effective model of the organic antiferromagnet λ-(BETS)2FeCl4 in its insulating phase, in which intriguing magnetic phenomena have been observed, where the small and large spins correspond to π electrons and 3d spins, respectively. BETS stands for bis(ethylenedithio)tetraselenafulvalene. We obtain the antiferromagnetic transition temperature TN and the sublattice magnetizations m(T) and M(T) of the small and large spins, respectively, as functions of the temperature T. When T increases, m(T) is constant with a slight decrease below TN, even where M(T) decreases significantly. When J1 ≫ J12 and J2 = 0, an analytical expression for TN is derived. The estimated value of TN and the behaviors of m(T) and M(T) agree with the observations of λ-(BETS)2FeCl4.

  17. Theory of magnetic properties and spin-wave dispersion for ferroamgnetic (Ga, Mn)As

    Czech Academy of Sciences Publication Activity Database

    König, J.; Jungwirth, Tomáš; MacDonald, A. H.

    2001-01-01

    Roč. 64, č. 18 (2001), s. 184423-1 - 184423-7 ISSN 0163-1829 R&D Projects: GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * spin waves Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.070, year: 2001

  18. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2016-05-01

    Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  19. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Energy Technology Data Exchange (ETDEWEB)

    Polzikova, N. I., E-mail: polz@cplire.ru; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P. [Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Mokhovaya 11, building 7, Moscow, 125009 (Russian Federation)

    2016-05-15

    We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  20. Magnetization rotation or generation of incoherent spin waves? Suggestions for a spin-transfer effect experiment

    International Nuclear Information System (INIS)

    Bazaliy, Y. B.; Jones, B. A.

    2002-01-01

    ''Spin-transfer'' torque is created when electric current is passed through metallic ferromagnets and may have interesting applications in spintronics. So far it was experimentally studied in ''collinear'' geometries, where it is difficult to predict whether magnetization will coherently rotate or spin-waves will be generated. Here we propose an easy modification of existing experiment in which the spin-polarization of incoming current will no longer be collinear with magnetization and recalculate the switching behavior of the device. We expect that a better agreement with the magnetization rotation theory will be achieved. That can be an important step in reconciling alternative points of view on the effect of spin-transfer torque

  1. Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

    International Nuclear Information System (INIS)

    Ono, K.; Inami, N.; Saito, K.; Takeichi, Y.; Kawana, D.; Yokoo, T.; Itoh, S.; Yano, M.; Shoji, T.; Manabe, A.; Kato, A.; Kaneko, Y.

    2014-01-01

    The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant D sw (100.0 ± 4.9 meV.Å 2 ) and the exchange stiffness constant A (6.6 ± 0.3 pJ/m)

  2. Resonant tunneling of spin-wave packets via quantized states in potential wells.

    Science.gov (United States)

    Hansen, Ulf-Hendrik; Gatzen, Marius; Demidov, Vladislav E; Demokritov, Sergej O

    2007-09-21

    We have studied the tunneling of spin-wave pulses through a system of two closely situated potential barriers. The barriers represent two areas of inhomogeneity of the static magnetic field, where the existence of spin waves is forbidden. We show that for certain values of the spin-wave frequency corresponding to the quantized spin-wave states existing in the well formed between the barriers, the tunneling has a resonant character. As a result, transmission of spin-wave packets through the double-barrier structure is much more efficient than the sequent tunneling through two single barriers.

  3. Resonant spin wave excitations in a magnonic crystal cavity

    Science.gov (United States)

    Kumar, N.; Prabhakar, A.

    2018-03-01

    Spin polarized electric current, injected into permalloy (Py) through a nano contact, exerts a torque on the magnetization. The spin waves (SWs) thus excited propagate radially outward. We propose an antidot magnonic crystal (MC) with a three-hole defect (L3) around the nano contact, designed so that the frequency of the excited SWs, lies in the band gap of the MC. L3 thus acts as a resonant SW cavity. The energy in this magnonic crystal cavity can be tapped by an adjacent MC waveguide (MCW). An analysis of the simulated micromagnetic power spectrum, at the output port of the MCW reveals stable SW oscillations. The quality factor of the device, calculated using the decay method, was estimated as Q > 105 for an injected spin current density of 7 ×1012 A/m2.

  4. Spin waves at the liquid 3He-4He interface

    International Nuclear Information System (INIS)

    Heff, A.; Candela, D.; Edwards, D.O.; Kumar, S.

    1987-01-01

    The properties of various interfaces in helium and, in particular, the interface between liquid 3 He and a solution of 3 He in 4 He, may be studied using spin waves. Assuming no transverse relaxation, the boundary condition for the transverse magnetization contains one complex kinetic coefficient, b. For the normal 3 He to 3 He- 4 He interface, b is related to the 3 He quasi-particle transmission probability antiτ, which we estimate from a simple model. A calculation of the spin wave absorption spectrum for a typical geometry shows that b and antiτ may be measured by NMR. Neither b nor antiτ is greatly affected when the pure 3 He enters the A phase, but both are strongly reduced in the B phase

  5. Collective spin wave and phonon excitations in ferromagnetic organic polymers

    International Nuclear Information System (INIS)

    Leong, Jit-Liang; Sun, Shih-Jye

    2013-01-01

    We proposed a model to investigate the properties of a conductive and ferromagnetic organic-polymer (OCP), which contains two collective excitations—spin wave and phonon—competing with each other; namely, the spin wave excitation accompanies the electron–phonon (e–ph) interactions in the conductive and ferromagnetic OCP. The ferromagnetism of the OCP is induced from the conductive carriers which couple with the phonon to become polarons. Due to the competition between both excitations, the Curie temperature (T C ) is sensitively suppressed by the e–ph interaction. In addition, an optimal T C with a small e–ph interaction exists in a specific density of conduction carrier, yet is contrary to the large e–ph interaction case. Furthermore, the dimerization, i.e. the atomic displacement induced from the e–ph interactions, increases with the strength of the e–ph interaction and decreases upon reaching the maximum dimerization. (paper)

  6. Spin wave steering in three-dimensional magnonic networks

    Science.gov (United States)

    Beginin, E. N.; Sadovnikov, A. V.; Sharaevskaya, A. Yu.; Stognij, A. I.; Nikitov, S. A.

    2018-03-01

    We report the concept of three-dimensional (3D) magnonic structures which are especially promising for controlling and manipulating magnon currents. The approach for fabrication of 3D magnonic crystals (MCs) and 3D magnonic networks is presented. A meander type ferromagnetic film grown at the top of the initially structured substrate can be a candidate for such 3D crystals. Using the finite element method, transfer matrix method, and micromagnetic simulations, we study spin-wave propagation in both isolated and coupled 3D MCs and reconstruct spin-wave dispersion and transmission response to elucidate the mechanism of magnonic bandgap formation. Our results show the possibility of the utilization of proposed structures for fabrication of a 3D magnonic network.

  7. Spin-density wave state in simple hexagonal graphite

    Science.gov (United States)

    Mosoyan, K. S.; Rozhkov, A. V.; Sboychakov, A. O.; Rakhmanov, A. L.

    2018-02-01

    Simple hexagonal graphite, also known as AA graphite, is a metastable configuration of graphite. Using tight-binding approximation, it is easy to show that AA graphite is a metal with well-defined Fermi surface. The Fermi surface consists of two sheets, each shaped like a rugby ball. One sheet corresponds to electron states, another corresponds to hole states. The Fermi surface demonstrates good nesting: a suitable translation in the reciprocal space superposes one sheet onto another. In the presence of the electron-electron repulsion, a nested Fermi surface is unstable with respect to spin-density-wave ordering. This instability is studied using the mean-field theory at zero temperature, and the spin-density-wave order parameter is evaluated.

  8. Spin wave propagation in perpendicular magnetized 20 nm Yttrium Iron Garnet with different antenna design

    Science.gov (United States)

    Chen, Jilei; Stueckler, Tobias; Zhang, Youguang; Zhao, Weisheng; Yu, Haiming; Chang, Houchen; Liu, Tao; Wu, Mingzhong; Liu, Chuanpu; Liao, Zhimin; Yu, Dapeng; Fert Beijing research institute Team; Colorado State University Team; Peking University Collaboration

    Magnonics offers a new way to transport information using spin waves free of charge current and could lead to a new paradigm in the area of computing. Forward volume (FV) mode spin wave with perpendicular magnetized configuration is suitable for spin wave logic device because it is free of non-reciprocity effect. Here, we study FV mode spin wave propagation in YIG thin film with an ultra-low damping. We integrated differently designed antenna i.e., coplanar waveguide and micro stripline with different dimensions. The k vectors of the spin waves defined by the design of the antenna are calculated using Fourier transform. We show FV mode spin wave propagation results by measuring S12 parameter from vector network analyzer and we extract the group velocity of the FV mode spin wave as well as its dispersion relations.

  9. Nonreciprocity of spin waves in metallized magnonic crystal

    International Nuclear Information System (INIS)

    Mruczkiewicz, M; Krawczyk, M; Gubbiotti, G; Tacchi, S; Filimonov, Yu A; Kalyabin, D V; Lisenkov, I V; Nikitov, S A

    2013-01-01

    The nonreciprocal properties of spin waves in metallized one-dimensional bi-component magnonic crystal composed of two materials with different magnetizations are investigated numerically. Nonreciprocity leads to the appearance of indirect magnonic band gaps for magnonic crystals with both low and high magnetization contrast. Specific features of the nonreciprocity in low contrast magnonic crystals lead to the appearance of several magnonic band gaps located within the first Brillouin zone for waves propagating along the metallized surface. Analysis of the spatial distribution of dynamic magnetization amplitudes explains the mechanism of dispersion band formation and hybridization between magnonic bands in magnonic crystals with metallization. (paper)

  10. Linear spin waves in a trapped Bose gas

    International Nuclear Information System (INIS)

    Nikuni, T.; Williams, J.E.; Clark, C.W.

    2002-01-01

    An ultracold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with 87 Rb atoms confined in a harmonic trap. We present a theory of the spin-wave collective modes based on the moment method for trapped gases. In the collisionless and hydrodynamic limits, we derive analytic expressions for the frequencies and damping rates of modes with dipole and quadrupole symmetry. We find that the frequency for a given mode is given by a temperature-independent function of the peak density n, and falls off as 1/n. We also find that, to a very good approximation, excitations in the radial and axial directions are decoupled. We compare our model to the numerical integration of a one-dimensional version of the kinetic equation and find very good qualitative agreement. The damping rates, however, show the largest deviation for intermediate densities, where one expects Landau damping--which is unaccounted for in our moment approach--to play a significant role

  11. Inelastic scattering of neutrons by spin waves in terbium

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Houmann, Jens Christian Gylden

    1966-01-01

    Measurements of spin-wave dispersion relations for magnons propagating in symmetry directions in ferromagnetic Tb; it is first experiment to give detailed information on magnetic excitations in heavy rare earths; Tb was chosen for these measurements because it is one of few rare-earth metals which...... does not have very high thermal-neutron capture cross section, so that inelastic neutron scattering experiments can give satisfactory information on magnon dispersion relations....

  12. Transverse spin and transverse momentum in scattering of plane waves

    OpenAIRE

    Saha, Sudipta; Singh, Ankit K.; Ray, Subir K.; Banerjee, Ayan; Gupta, Subhasish Dutta; Ghosh, Nirmalya

    2016-01-01

    We study the near field to the far field evolution of spin angular momentum (SAM) density and the Poynting vector of the scattered waves from spherical scatterers. The results show that at the near field, the SAM density and the Poynting vector are dominated by their transverse components. While the former (transverse SAM) is independent of the helicity of the incident circular polarization state, the latter (transverse Poynting vector) depends upon the polarization state. It is further demon...

  13. Overcoming thermal noise in non-volatile spin wave logic

    Science.gov (United States)

    Dutta, Sourav; Nikonov, Dmitri; Manipatruni, Sasikanth; Young, Ian; Naeemi, Azad

    Spin waves are propagating disturbances in magnetically ordered materials. To compete as a promising candidate for beyond-CMOS application, the all-magnon based computing system must undergo the essential steps of careful selection of materials and demonstrate robustness with respect to thermal noise/variability. Here, we identify suitable materials and investigate two viable options for translating the theoretical idea of phase-dependent switching of the spin wave detector to a practical realization of a thermally reliable magnonic device by - (a) using the built-in strain in the ME cell, arising from the lattice mismatch and/or thermal expansion coefficient mismatch between the film and the substrate, for compensation of the demagnetization, and (b) using an exchange-spring structure that exhibits a strong exchange-coupling between the ME cell and PMA SWB and provides a modification of the energy landscape of the ME cell magnet. A high switching success and error-free logic functionality can be ensured if the amplitude of the detected spin wave () remains higher than a threshold value of around 6°C and the detected phase falls within the window from 280°C through 0 to 20°C or from 100°C to 200°C with a maximum allowable ϕ range of around 100°C.

  14. Part I: Spin wave dynamics in YIG spheres

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    An experimental study is made of the interactions between spin wave modes excited in a sphere of yttrium iron garnet by pumping the Suhl subsidiary absorption with microwaves. The dynamical behavior of the magnetization is observed under high resolution by varying the dc field and microwave pump power. Varied behavior is found: (1) onset of the Suhl instability by excitation of a single spin wave mode; (2) when two or more modes are excited, interactions lead to auto-oscillations displaying period-doubling to chaos; (3) quasiperiodicity, locking, and chaos occur when three or more modes are excited; (4) abrupt transition to wide band power spectra (i.e., turbulence), with hysteresis; (5) irregular relaxation oscillations and aperiodic spiking behavior. A theoretical model is developed using the plane wave approximation obtaining the lowest order nonlinear interaction terms between the excited modes. Extension of this analysis to the true spherical spin-modes is discussed. Bifurcation behavior is examined, and dynamical behavior is numerically computed and compared to the experimental data. A theory is developed regarding the nature of the experimentally observed relaxation oscillations and spiking behavior based on the interaction of ''weak'' and ''strong'' modes, and this is demonstrated in the numerical simulations for two modes. Quasiperiodicity is shown to occur in the numerical study when at least 3 modes are excited with appropriate parameter values. A possible mechanism for generating microwave subharmonics at half of the pumping frequency is discussed. 57 refs., 25 figs., 5 tabs

  15. Quantum dust magnetosonic waves with spin and exchange correlation effects

    Energy Technology Data Exchange (ETDEWEB)

    Maroof, R.; Qamar, A. [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); National Center for Physics, Shahdra Valley Road, Islamabad 44000 (Pakistan)

    2016-01-15

    Dust magnetosonic waves are studied in degenerate dusty plasmas with spin and exchange correlation effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, spin magnetization energy, and exchange correlation, a generalized dispersion relation is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. The exchange-correlation potentials are used, based on the adiabatic local-density approximation, and can be described as a function of the electron density. For three different values of angle, the dispersion relation is reduced to three different modes under the low frequency magnetohydrodynamic assumptions. It is found that the effects of quantum corrections in the presence of dust concentration significantly modify the dispersive properties of these modes. The results are useful for understanding numerous collective phenomena in quantum plasmas, such as those in compact astrophysical objects (e.g., the cores of white dwarf stars and giant planets) and in plasma-assisted nanotechnology (e.g., quantum diodes, quantum free-electron lasers, etc.)

  16. Quantum dust magnetosonic waves with spin and exchange correlation effects

    Science.gov (United States)

    Maroof, R.; Mushtaq, A.; Qamar, A.

    2016-01-01

    Dust magnetosonic waves are studied in degenerate dusty plasmas with spin and exchange correlation effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, spin magnetization energy, and exchange correlation, a generalized dispersion relation is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. The exchange-correlation potentials are used, based on the adiabatic local-density approximation, and can be described as a function of the electron density. For three different values of angle, the dispersion relation is reduced to three different modes under the low frequency magnetohydrodynamic assumptions. It is found that the effects of quantum corrections in the presence of dust concentration significantly modify the dispersive properties of these modes. The results are useful for understanding numerous collective phenomena in quantum plasmas, such as those in compact astrophysical objects (e.g., the cores of white dwarf stars and giant planets) and in plasma-assisted nanotechnology (e.g., quantum diodes, quantum free-electron lasers, etc.).

  17. Topological Magnonics: A Paradigm for Spin-Wave Manipulation and Device Design

    Science.gov (United States)

    Wang, X. S.; Zhang, H. W.; Wang, X. R.

    2018-02-01

    Conventional magnonic devices use magnetostatic waves whose properties are sensitive to device geometry and the details of magnetization structure, so the design and the scalability of the device or circuitry are difficult. We propose topological magnonics, in which topological exchange spin waves are used as information carriers, that do not suffer from conventional problems of magnonic devices with additional nice features of nanoscale wavelength and high frequency. We show that a perpendicularly magnetized ferromagnet on a honeycomb lattice is generically a topological magnetic material in the sense that topologically protected chiral edge spin waves exist in the band gap as long as a spin-orbit-induced nearest-neighbor pseudodipolar interaction (and/or a next-nearest-neighbor Dzyaloshinskii-Moriya interaction) is present. The edge spin waves propagate unidirectionally along sample edges and domain walls regardless of the system geometry and defects. As a proof of concept, spin-wave diodes, spin-wave beam splitters, and spin-wave interferometers are designed by using sample edges and domain walls to manipulate the propagation of topologically protected chiral spin waves. Since magnetic domain walls can be controlled by magnetic fields or electric current or fields, one can essentially draw, erase, and redraw different spin-wave devices and circuitry on the same magnetic plate so that the proposed devices are reconfigurable and tunable. The topological magnonics opens up an alternative direction towards a robust, reconfigurable and scalable spin-wave circuitry.

  18. Spin-wave propagation spectrum in magnetization-modulated cylindrical nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhi-xiong; Wang, Meng-ning; Nie, Yao-zhuang; Wang, Dao-wei; Xia, Qing-lin [School of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Wei [School of Physics and Electronics, Central South University, Changsha 410083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Zeng, Zhong-ming [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Guo, Guang-hua, E-mail: guogh@mail.csu.edu.cn [School of Physics and Electronics, Central South University, Changsha 410083 (China)

    2016-09-15

    Spin-wave propagation in periodic magnetization-modulated cylindrical nanowires is studied by micromagnetic simulation. Spin wave scattering at the interface of two magnetization segments causes a spin-wave band structure, which can be effectively tuned by changing either the magnetization modulation level or the period of the cylindrical nanowire magnonic crystal. The bandgap width is oscillating with either the period or magnetization modulation due to the oscillating variation of the spin wave transmission coefficient through the interface of the two magnetization segments. Analytical calculation based on band theory is used to account for the micromagnetic simulation results. - Highlights: • A magnetization-modulated cylindrical nanowire magnonic crystal is proposed. • Propagating characteristics of spin waves in such magnonic crystal are studied. • Spin-wave spectra can be manipulated by changing modulation level and period.

  19. Non-equilibrium study of spin wave interference in systems with both Rashba and Dresselhaus (001) spin-orbit coupling

    International Nuclear Information System (INIS)

    Chen, Kuo-Chin; Su, Yu-Hsin; Chang, Ching-Ray; Chen, Son-Hsien

    2014-01-01

    We study the electron spin transport in two dimensional electron gas (2DEG) system with both Rashba and Dresselhaus (001) spin-orbital coupling (SOC). We assume spatial behavior of spin precession in the non-equilibrium transport regime, and study also quantum interference induced by non-Abelian spin-orbit gauge field. The method we adopt in this article is the non-equilibrium Green's function within a tight binding framework. We consider one ferromagnetic lead which injects spin polarized electron to a system with equal strength of Rashba and Dresselhaus (001) SOC, and we observe the persistent spin helix property. We also consider two ferromagnetic leads injecting spin polarized electrons into a pure Dresselhaus SOC system, and we observe the resultant spin wave interference pattern

  20. Gravity dual of spin and charge density waves

    Science.gov (United States)

    Jokela, Niko; Järvinen, Matti; Lippert, Matthew

    2014-12-01

    At high enough charge density, the homogeneous state of the D3-D7' model is unstable to fluctuations at nonzero momentum. We investigate the end point of this instability, finding a spatially modulated ground state, which is a charge and spin density wave. We analyze the phase structure of the model as a function of chemical potential and magnetic field and find the phase transition from the homogeneous state to be first order, with a second-order critical point at zero magnetic field.

  1. Spin-waves in antiferromagnetic single crystal LiFePO$_4$

    OpenAIRE

    Li, Jiying; Garlea, Vasile O.; Zarestky, Jerel L.; Vaknin, David

    2005-01-01

    Spin-wave dispersions in the antiferromagnetic state of single crystal LiFePO$_4$ were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (010) reflection along both {\\it a}$^\\ast$ and {\\it b}$^\\ast$ reciprocal-space directions reflect the anisotropic coupling of the layered Fe$^{2+}$ (S = 2) spin-system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin-Hamiltonian in-plane nearest- ...

  2. Coherent Waves in Seismic Researches

    Science.gov (United States)

    Emanov, A.; Seleznev, V. S.

    2013-05-01

    reflected waves. With use of developed algorithms of head wave conversion in time sections a work of studying of refracting boundaries in Siberia have been executed. Except for the research by method of refracting waves, the conversion of head waves in time sections, applied to seismograms of reflected wave method, allows to obtain information about refracting horizons in upper part of section in addition to reflecting horizons data. Recovery method of wave field coherent components is the basis of the engineering seismology on the level of accuracy and detail. In seismic microzoning resonance frequency of the upper part of section are determined on the basis of this method. Maps of oscillation amplification and result accuracy are constructed for each of the frequencies. The same method makes it possible to study standing wave field in buildings and constructions with high accuracy and detail, realizing diagnostics of their physical state on set of natural frequencies and form of self-oscillations, examined with high detail. The method of standing waves permits to estimate a seismic stability of structure on new accuracy level.

  3. Design of a spin-wave majority gate employing mode selection

    Energy Technology Data Exchange (ETDEWEB)

    Klingler, S., E-mail: klingler@physik.uni-kl.de; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

    2014-10-13

    The design of a microstructured, fully functional spin-wave majority gate is presented and studied using micromagnetic simulations. This all-magnon logic gate consists of three-input waveguides, a spin-wave combiner, and an output waveguide. In order to ensure the functionality of the device, the output waveguide is designed to perform spin-wave mode selection. We demonstrate that the gate evaluates the majority of the input signals coded into the spin-wave phase. Moreover, the all-magnon data processing device is used to perform logic AND-, OR-, NAND-, and NOR- operations.

  4. Mapping of spin wave propagation in a one-dimensional magnonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ordóñez-Romero, César L., E-mail: cloro@fisica.unam.mx; Lazcano-Ortiz, Zorayda; Aguilar-Huerta, Melisa; Monsivais, Guillermo [Instituto de Física, Universidad Nacional Autónoma de México, CU, México D.F. 04510 (Mexico); Drozdovskii, Andrey; Kalinikos, Boris [St. Petersburg Electrotechnical University, 197376 St. Petersburg (Russian Federation); International laboratory “MultiferrLab,” ITMO University, 197101 St. Petersburg (Russian Federation); Domínguez-Juárez, J. L. [Cátedras CONACyT, CFATA, Universidad Nacional Autónoma de México, Juriquilla, Querétaro 76230 (Mexico); Lopez-Maldonado, Guillermo [Universidad Autónoma Metropolitana, Lerma de Villada, 52006 Estado de México (Mexico); Qureshi, Naser; Kolokoltsev, Oleg [CCADET, Universidad Nacional Autónoma de México, CU, México D.F. 04510 (Mexico)

    2016-07-28

    The formation and evolution of spin wave band gaps in the transmission spectrum of a magnonic crystal have been studied. A time and space resolved magneto inductive probing system has been used to map the spin wave propagation and evolution in a geometrically structured yttrium iron garnet film. Experiments have been carried out using (1) a chemically etched magnonic crystal supporting the propagation of magnetostatic surface spin waves, (2) a short microwave pulsed excitation of the spin waves, and (3) direct spin wave detection using a movable magneto inductive probe connected to a synchronized fast oscilloscope. The results show that the periodic structure not only modifies the spectra of the transmitted spin waves but also influences the distribution of the spin wave energy inside the magnonic crystal as a function of the position and the transmitted frequency. These results comprise an experimental confirmation of Bloch′s theorem in a spin wave system and demonstrate good agreement with theoretical observations in analogue phononic and photonic systems. Theoretical prediction of the structured transmission spectra is achieved using a simple model based on microwave transmission lines theory. Here, a spin wave system illustrates in detail the evolution of a much more general physical concept: the band gap.

  5. Spin waves in terbium. II. Magnon-phonon interaction

    International Nuclear Information System (INIS)

    Jensen, J.; Houmann, J.G.

    1975-01-01

    The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been explained by Liu as originating from the mixing of the spin states of the conduction electrons due to the spin-orbit coupling. We find that this coupling mechanism introduces interactions which violate the selection rules for a simple ferromagnet. The interactions between the magnons and phonons propagating in the c direction of Tb have been studied experimentally by means of inelastic neutron scatttering. The magnons are coupled to both the acoustic- and optical-transverse phonons. By studying the behavior of the acoustic-optical coupling, we conclude that it is a spin-mixed-induced coupling as proposed by Liu. The coupled magnon--transverse-phonon system for the c direction of Tb is analyzed in detail, and the strengths of the couplings are deduced as a function of wave vector by combining the experimental studies with the theory

  6. Exchange anisotropy pinning of a standing spin-wave mode

    Science.gov (United States)

    Magaraggia, R.; Kennewell, K.; Kostylev, M.; Stamps, R. L.; Ali, M.; Greig, D.; Hickey, B. J.; Marrows, C. H.

    2011-02-01

    Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin-wave thickness mode in Ni80Fe20/Ir25Mn75 exchange-biased bilayers was studied for a range of Ir25Mn75 thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique “fingerprint” of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet-antiferromagnet interface anisotropy. Thermal effects are studied for ultrathin antiferromagnetic Ir25Mn75 thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

  7. Spin wave dynamics in Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-09-15

    The spin wave dynamics, including the magnetization, spin wave dispersion relation, and energy level splitting, of Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes are systematically calculated by use of the double-time Green’s function method within the random phase approximation. The role of temperature, diameter of the tube, and wave vector on spin wave energy spectrum and energy level splitting are carefully analyzed. There are two categories of spin wave modes, which are quantized and degenerate, and the total number of independent magnon branches is dependent on diameter of the tube, caused by the physical symmetry of nanotubes. Moreover, the number of flat spin wave modes increases with diameter of the tube rising. The spin wave energy and the energy level splitting decrease with temperature rising, and become zero as temperature reaches the critical point. At any temperature, the energy level splitting varies with wave vector, and for a larger wave vector it is smaller. When pb=π, the boundary of first Brillouin zone, spin wave energies are degenerate, and the energy level splittings are zero.

  8. Brillouin-Mandelstam spectroscopy of standing spin waves in a ferrite waveguide

    Science.gov (United States)

    Balinskiy, Michael; Kargar, Fariborz; Chiang, Howard; Balandin, Alexander A.; Khitun, Alexander G.

    2018-05-01

    This article reports results of experimental investigation of the spin wave interference over large distances in the Y3Fe2(FeO4)3 waveguide using Brillouin-Mandelstam spectroscopy. Two coherent spin waves are excited by the micro-antennas fabricated at the edges of the waveguide. The amplitudes of the input spin waves are adjusted to provide approximately the same intensity in the central region of the waveguide. The relative phase between the excited spin waves is controlled by the phase shifter. The change of the local intensity distribution in the standing spin wave is monitored using Brillouin-Mandelstam light scattering spectroscopy. Experimental data demonstrate the oscillation of the scattered light intensity depending on the relative phase of the interfering spin waves. The oscillations of the intensity, tunable via the relative phase shift, are observed as far as 7.5 mm away from the spin-wave generating antennas at room temperature. The obtained results are important for developing techniques for remote control of spin currents, with potential applications in spin-based memory and logic devices.

  9. Magnetic Spin Waves in CsNiF3 with an Applied Field

    DEFF Research Database (Denmark)

    Steiner, M.; Kjems, Jørgen

    1977-01-01

    The spin wave dispersion in the planar 1D ferromagnet CsNiF3 has been measured by inelastic neutron scattering in an external field. The spin wave linewidths are found to decrease with increasing field and become resolution-limited for H>10 kG at 4.2K. At high fields, H>10 kG, both energies...

  10. Are Gravitational Waves Spinning Down PSR J1023+0038?

    Science.gov (United States)

    Haskell, B; Patruno, A

    2017-10-20

    The pulsar J1023+0038 rotates with a frequency ν≈592  Hz and has been observed to transition between a radio state, during which it is visible as a millisecond radio pulsar, and a low-mass x-ray binary (LMXB) state, during which accretion powered x-ray pulsations are visible. Timing during the two phases reveals that during the LMXB phase the neutron star is spinning down at a rate of ν[over ˙]≈-3×10^{-15}  Hz/s, which is approximately 27% faster than the rate measured during the radio phase, ν[over ˙]≈-2.4×10^{-15}  Hz/s, and is at odds with the predictions of accretion models. We suggest that the increase in spin-down rate is compatible with gravitational wave emission, particularly with the creation of a "mountain" during the accretion phase. We show that asymmetries in pycnonuclear reaction rates in the crust can lead to a large enough mass quadrupole to explain the observed spin-down rate, which thus far has no other self-consistent explanation. We also suggest two observational tests of this scenario, involving radio timing at the onset of the next millisecond radio pulsar phase, when the mountain should dissipate, and accurate timing during the next LMXB phase to track the increase in torque as the mountain builds up. Another possibility is that an unstable r mode with an amplitude α≈5×10^{-8} may be present in the system.

  11. Theory of spin and lattice wave dynamics excited by focused laser pulses

    Science.gov (United States)

    Shen, Ka; Bauer, Gerrit E. W.

    2018-06-01

    We develop a theory of spin wave dynamics excited by ultrafast focused laser pulses in a magnetic film. We take into account both the volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. We show that the sound waves generated by local heating by an ultrafast focused laser pulse can excite a wide spectrum of spin waves (on top of a dominant magnon–phonon contribution). Good agreement with recent experiments supports the validity of the model.

  12. Spin waves in terbium. III. Magnetic anisotropy at zero wave vector

    DEFF Research Database (Denmark)

    Houmann, Jens Christian Gylden; Jensen, J.; Touborg, P.

    1975-01-01

    The energy gap at zero wave vector in the spin-wave dispersion relation of ferromagnetic. Tb has been studied by inelastic neutron scattering. The energy was measured as a function of temperature and applied magnetic field, and the dynamic anisotropy parameters were deduced from the results...... the effects of zero-point deviations from the fully aligned ground state, and we tentatively propose polarization-dependent two-ion couplings as their origin........ The axial anisotropy is found to depend sensitively on the orientation of the magnetic moments in the basal plane. This behavior is shown to be a convincing indication of considerable two-ion contributions to the magnetic anisotropy at zero wave vector. With the exception of the sixfold basal...

  13. Ion Bernstein wave heating research

    International Nuclear Information System (INIS)

    Ono, Masayuki.

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity (ω/k perpendicular ∼ V Ti much-lt V α ) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion α-particles. In addition, the property of IBW's that k perpendicular ρ i ∼ 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research

  14. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength

    OpenAIRE

    Savochkin, I. V.; J?ckl, M.; Belotelov, V. I.; Akimov, I. A.; Kozhaev, M. A.; Sylgacheva, D. A.; Chernov, A. I.; Shaposhnikov, A. N.; Prokopov, A. R.; Berzhansky, V. N.; Yakovlev, D. R.; Zvezdin, A. K.; Bayer, M.

    2017-01-01

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with ...

  15. Engineering spin-wave channels in submicrometer magnonic waveguides

    Directory of Open Access Journals (Sweden)

    XiangJun Xing

    2013-03-01

    Full Text Available Based on micromagnetic simulations and model calculations, we demonstrate that degenerate well and barrier magnon modes can exist concurrently in a single magnetic waveguide magnetized perpendicularly to the long axis in a broad frequency band, corresponding to copropagating edge and centre spin waves, respectively. The dispersion relations of these magnon modes clearly show that the edge and centre modes possess much different wave characteristics. By tailoring the antenna size, the edge mode can be selectively activated. If the antenna is sufficiently narrow, both the edge and centre modes are excited with considerable efficiency and propagate along the waveguide. By roughening the lateral boundary of the waveguide, the characteristics of the relevant channel can be easily engineered. Moreover, the coupling of the edge and centre modes can be conveniently controlled by scaling the width of the waveguide. For a wide waveguide with a narrow antenna, the edge and centre modes travel relatively independently in spatially-separate channels, whereas for a narrow strip, these modes strongly superpose in space. These discoveries might find potential applications in emerging magnonic devices.

  16. Synchronization of propagating spin-wave modes in a double-contact spin-torque oscillator: A micromagnetic study

    International Nuclear Information System (INIS)

    Puliafito, V.; Consolo, G.; Lopez-Diaz, L.; Azzerboni, B.

    2014-01-01

    This work tackles theoretical investigations on the synchronization of spin-wave modes generated by spin-transfer-torque in a double nano-contact geometry. The interaction mechanisms between the resulting oscillators are analyzed in the case of propagating modes which are excited via a normal-to-plane magnetic bias field. To characterize the underlying physical mechanisms, a multi-domain analysis is performed. It makes use of an equivalent electrical circuit, to deduce the output electrical power, and of micromagnetic simulations, through which information on the frequency spectra and on the spatial distribution of the wavefront of the emitted spin-waves is extracted. This study provides further and intriguing insights into the physical mechanisms giving rise to synchronization of spin-torque oscillators

  17. Recent advances of spin crossover research

    NARCIS (Netherlands)

    Gutlich, P; van Koningsbruggen, PJ; Renz, F; Schonherr, T

    2004-01-01

    Thermal spin transition (spin crossover), one of the most fascinating dynamic electronic structure phenomena occurring in coordination compounds of third row transition metal ions, mostly of iron(II), iron(III) and cobalt(II) with critical ligand field strengths competing with the spin pairing

  18. High-efficiency control of spin-wave propagation in ultra-thin yttrium iron garnet by the spin-orbit torque

    Energy Technology Data Exchange (ETDEWEB)

    Evelt, M.; Demidov, V. E., E-mail: demidov@uni-muenster.de [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, 48149 Muenster (Germany); Bessonov, V. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Yekaterinburg 620041 (Russian Federation); Demokritov, S. O. [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, 48149 Muenster (Germany); M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Yekaterinburg 620041 (Russian Federation); Prieto, J. L. [Instituto de Sistemas Optoelectrónicos y Microtecnologa (UPM), Ciudad Universitaria, Madrid 28040 (Spain); Muñoz, M. [IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), PTM, E-28760 Tres Cantos, Madrid (Spain); Ben Youssef, J. [Laboratoire de Magnétisme de Bretagne CNRS, Université de Bretagne Occidentale, 29285 Brest (France); Naletov, V. V. [Service de Physique de l' État Condensé, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Institute of Physics, Kazan Federal University, Kazan 420008 (Russian Federation); Loubens, G. de [Service de Physique de l' État Condensé, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Klein, O. [INAC-SPINTEC, CEA/CNRS and Univ. Grenoble Alpes, 38000 Grenoble (France); Collet, M.; Garcia-Hernandez, K.; Bortolotti, P.; Cros, V.; Anane, A. [Unité Mixte de Physique CNRS, Thales, Univ. Paris Sud, Université Paris-Saclay, 91767 Palaiseau (France)

    2016-04-25

    We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by the nonlinear scattering of the coherent spin waves from current-induced excitations.

  19. High-efficiency control of spin-wave propagation in ultra-thin yttrium iron garnet by the spin-orbit torque

    International Nuclear Information System (INIS)

    Evelt, M.; Demidov, V. E.; Bessonov, V.; Demokritov, S. O.; Prieto, J. L.; Muñoz, M.; Ben Youssef, J.; Naletov, V. V.; Loubens, G. de; Klein, O.; Collet, M.; Garcia-Hernandez, K.; Bortolotti, P.; Cros, V.; Anane, A.

    2016-01-01

    We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by the nonlinear scattering of the coherent spin waves from current-induced excitations.

  20. Gravitational waves from a spinning particle scattered by a relativistic star: Axial mode case

    International Nuclear Information System (INIS)

    Tominaga, Kazuhiro; Saijo, Motoyuki; Maeda, Kei-ichi

    2001-01-01

    We use a perturbation method to study gravitational waves from a spinning test particle scattered by a relativistic star. The present analysis is restricted to axial modes. By calculating the energy spectrum, the wave forms, and the total energy and angular momentum of gravitational waves, we analyze the dependence of the emitted gravitational waves on particle spin. For a normal neutron star, the energy spectrum has one broad peak whose characteristic frequency corresponds to the angular velocity at the turning point (a periastron). Since the turning point is determined by the orbital parameter, there exists a dependence of the gravitational wave on particle spin. We find that the total energy of l=2 gravitational waves gets larger as the spin increases in the antiparallel direction to the orbital angular momentum. For an ultracompact star, in addition to such an orbital contribution, we find the quasinormal modes excited by a scattered particle, whose excitation rate to gravitational waves depends on the particle spin. We also discuss the ratio of the total angular momentum to the total energy of gravitational waves and explain its spin dependence

  1. Spin waves in the soft layer of exchange-coupled soft/hard bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Zheng-min; Ge, Su-qin; Wang, Xi-guang; Li, Zhi-xiong; Xia, Qing-lin; Wang, Dao-wei; Nie, Yao-zhuang; Guo, Guang-hua, E-mail: guogh@mail.csu.edu.cn [School of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Wei [School of Physics and Electronics, Central South University, Changsha 410083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Zeng, Zhong-ming [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2016-05-15

    The magnetic dynamical properties of the soft layer in exchange-coupled soft/hard bilayers have been investigated numerically using a one-dimensional atomic chain model. The frequencies and spatial profiles of spin wave eigenmodes are calculated during the magnetization reversal process of the soft layer. The spin wave modes exhibit a spatially modulated amplitude, which is especially evident for high-order modes. A dynamic pinning effect of surface magnetic moment is observed. The spin wave eigenfrequency decreases linearly with the increase of the magnetic field in the uniformly magnetized state and increases nonlinearly with field when spiral magnetization configuration is formed in the soft layer.

  2. Spin waves in the soft layer of exchange-coupled soft/hard bilayers

    Directory of Open Access Journals (Sweden)

    Zheng-min Xiong

    2016-05-01

    Full Text Available The magnetic dynamical properties of the soft layer in exchange-coupled soft/hard bilayers have been investigated numerically using a one-dimensional atomic chain model. The frequencies and spatial profiles of spin wave eigenmodes are calculated during the magnetization reversal process of the soft layer. The spin wave modes exhibit a spatially modulated amplitude, which is especially evident for high-order modes. A dynamic pinning effect of surface magnetic moment is observed. The spin wave eigenfrequency decreases linearly with the increase of the magnetic field in the uniformly magnetized state and increases nonlinearly with field when spiral magnetization configuration is formed in the soft layer.

  3. Interplay of charge density wave and spin density wave in high-T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, B. [Government Science College, Malkangiri 764 048 (India)], E-mail: brunda@iopb.res.in; Raj, B.K. [B.J.B. College, Bhubaneswar 751 014 (India); Rout, G.C. [Condensed Matter Physics Group, P.G. Department of Applied Physics and Ballistics, F.M. University, Balasore 756 019 (India)], E-mail: gcr@iopb.res.in

    2008-12-01

    We present a mean-field theory theoretical model study for the coexistence of the two strongly interacting charge density wave (CDW) and spin density wave (SDW) for high-T{sub c} cuprates in the underdoped region before the onset of the superconductivity in the system. The analytic expressions for the temperature dependence of the CDW and SDW order parameters are derived and solved self-consistently. Their interplay is studied by varying their respective coupling constants. It is observed that in the interplay region both the gap parameters exhibit very strong dependence of their gap values for the coupling constants. Further, the electronic density of states (DOS) for the conduction electrons, which represents the scanning tunneling data, show two gap parameters in the interplay region from these experimental data. Our model can help to determine separately the CDW and SDW parameters.

  4. Interplay of charge density wave and spin density wave in high-Tc superconductors

    International Nuclear Information System (INIS)

    Pradhan, B.; Raj, B.K.; Rout, G.C.

    2008-01-01

    We present a mean-field theory theoretical model study for the coexistence of the two strongly interacting charge density wave (CDW) and spin density wave (SDW) for high-T c cuprates in the underdoped region before the onset of the superconductivity in the system. The analytic expressions for the temperature dependence of the CDW and SDW order parameters are derived and solved self-consistently. Their interplay is studied by varying their respective coupling constants. It is observed that in the interplay region both the gap parameters exhibit very strong dependence of their gap values for the coupling constants. Further, the electronic density of states (DOS) for the conduction electrons, which represents the scanning tunneling data, show two gap parameters in the interplay region from these experimental data. Our model can help to determine separately the CDW and SDW parameters

  5. Angle-resolved spin wave band diagrams of square antidot lattices studied by Brillouin light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G.; Tacchi, S. [Istituto Officina dei Materiali del Consiglio Nazionale delle Ricerche (IOM-CNR), Sede di Perugia, c/o Dipartimento di Fisica e Geologia, Via A. Pascoli, I-06123 Perugia (Italy); Montoncello, F.; Giovannini, L. [Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via G. Saragat 1, I-44122 Ferrara (Italy); Madami, M.; Carlotti, G. [Dipartimento di Fisica e Geologia, Università di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Ding, J.; Adeyeye, A. O. [Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-06-29

    The Brillouin light scattering technique has been exploited to study the angle-resolved spin wave band diagrams of squared Permalloy antidot lattice. Frequency dispersion of spin waves has been measured for a set of fixed wave vector magnitudes, while varying the wave vector in-plane orientation with respect to the applied magnetic field. The magnonic band gap between the two most dispersive modes exhibits a minimum value at an angular position, which exclusively depends on the product between the selected wave vector magnitude and the lattice constant of the array. The experimental data are in very good agreement with predictions obtained by dynamical matrix method calculations. The presented results are relevant for magnonic devices where the antidot lattice, acting as a diffraction grating, is exploited to achieve multidirectional spin wave emission.

  6. Spin-waves in Antiferromagnetic Single-crystal LiFePO4

    International Nuclear Information System (INIS)

    Li, Jiying; Garlea, Vasile O.; Zarestky, Jarel; Vaknin, D.

    2006-01-01

    Spin-wave dispersions in the antiferromagnetic state of single-crystal LiFePO 4 were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (0,1,0) reflection along both a* and b* reciprocal-space directions reflect the anisotropic coupling of the layered Fe 2+ (S=2) spin system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin Hamiltonian in-plane nearest- and next-nearest-neighbor interactions (J 1 and J 2 ), inter-plane nearest-neighbor interactions (J(perpendicular)) and a single-ion anisotropy (D). A weak (0,1,0) magnetic peak was observed in elastic neutron scattering studies of the same crystal indicating that the ground state of the staggered iron moments is not along the (0,1,0) direction, as previously reported from polycrystalline samples studies, but slightly rotated away from this axis.

  7. Electromagnetic wave energy conversion research

    Science.gov (United States)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  8. Improved spin wave theory: An application to the spin-1/2 antiferromagnetic Heisenberg model on a square lattice

    International Nuclear Information System (INIS)

    Tao, Ruibao.

    1991-09-01

    A method is developed to make a Bose transformation which is restricted in proper space. A self-consistent independent spin wave representation (SCISWR) is found for two dimensional isotropic antiferromagnet of Heisenberg square lattices. In the SCISWR, we have successfully done the renormalization from both the dynamic and kinematic interaction and calculated the corrections from the correlations of the nearest neighbour and next nearest neighbour sites. An anisotropic excitation energy of spin wave in improper space is found self-consistently and has a gap. The difficulty of divergence appearing from higher order perturbation terms in the conventional spin wave theory has been overcome and the convergence in our approach seems quite good. We find the energy of ground state E approx. -0.659 in low order approximation and the magnetization of sublattice M z = 0.430 x (N/2) for system with spin 1/2. It is also proved that a physical spin excitation restricted in proper space is still isotropic and has no gap. (author). 17 refs

  9. Width dependent transition of quantized spin-wave modes in Ni80Fe20 square nanorings

    Science.gov (United States)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Rousseau, Olivier; Otani, YoshiChika; Barman, Anjan

    2014-10-01

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni80Fe20 nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  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. A cluster-bethe-lattice approach to spin-waves in dilute ferromagnets

    International Nuclear Information System (INIS)

    Salzberg, J.B.; Silva, C.E.T.G. da; Falicov, L.M.

    1975-01-01

    The spin-wave spectra of a dilute ferromagnet within the cluster-bethe-lattice approximation is studied. Short range order effects for the alloy are included. A study of finite size clusters connected at their edges to Bethe lattices of the same coordination number allows one to determine:(i) the stability condition for the magnetic system; (ii) the continuum spin-wave local density of states and (iii) the existence of localized states below and above the continuum states

  12. Suhl instabilities for spin waves in ferromagnetic nanostripes and ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Haghshenasfard, Zahra, E-mail: zhaghshe@uwo.ca; Nguyen, Hoa T.; Cottam, Michael G., E-mail: cottam@uwo.ca

    2017-03-15

    A microscopic (or Hamiltonian-based) theory is employed for the spin-wave instability thresholds of nonlinear processes in ultrathin ferromagnetic stripes and films under perpendicular pumping with an intense microwave field. The spatially-quantized linear spin waves in these nanostructures may participate in parametric processes through the three-magnon interactions (the first-order Suhl process) and the four-magnon interactions (the second-order Suhl process) when pumped. By contrast with most previous studies of spin-wave instabilities made for larger samples, where macroscopic (or continuum) theories involving Maxwell's equations for magnetic dipolar effects are used, a discrete lattice of effective spins is employed. Then a dipole-exchange spin Hamiltonian is employed to investigate the behavior of the quantized spin waves under perpendicular pumping, when modifications due to the more extensive spatial confinement and edges effects in these nanostructures become pronounced. The instability thresholds versus applied magnetic field are calculated, with emphasis on the size effects and geometries of the nanostructures and on the different relative strengths of the magnetic dipole-dipole and exchange interactions in materials. Numerical results are presented using parameters for Permalloy, YIG, and EuS. - Highlights: • Suhl instabilities for spin waves in magnetic stripes and films are investigated. • Three- and four-magnon processes in perpendicular pumping are taken into account. • Numerical applications are made to Permalloy, YIG, and EuS.

  13. Assessing the Detectability of Gravitational Waves from Coalescing Binary Black Holes with Precessing Spin

    Science.gov (United States)

    Frederick, Sara; Privitera, Stephen; Weinstein, Alan J.; LIGO Scientific Collaboration

    2015-01-01

    The Advanced LIGO and Virgo gravitational wave detectors will come online within the year and are expected to outperform the strain sensitivity of initial LIGO/Virgo detectors by an order of magnitude and operate with greater bandwidth, possibly to frequencies as low as 10 Hz. Coalescing binary black holes (BBH) are anticipated to be among the most likely sources of gravitational radiation observable by the detectors. Searches for such systems benefit greatly from the use of accurate predictions for the gravitational wave signal to filter the data. The component black holes of these systems are predicted to have substantial spin, which greatly influences the gravitational waveforms from these sources; however, recent LIGO/Virgo searches have made use of banks of waveform models which neglect the effects of the component spins. The inclusion of spinning components is relatively simplified when the spins are taken to be aligned with the orbital angular momentum, though the difficult task of including precession (allowing for mis-aligned component spins) remains a goal of this work. We aim to assess the ability of the GSTLAL gravitational wave search pipeline using IMR aligned-spin template waveforms to recover signals from generically spinning black hole binaries injected into simulated Advanced LIGO and Virgo detector noise. If black holes are highly spinning as predicted, use of aligned-spin template banks in upcoming searches could increase the detection rate of these systems in Advanced LIGO and Virgo data, providing the opportunity for a deeper understanding of the sources.

  14. Counter-rotating standing spin waves: A magneto-optical illusion

    Science.gov (United States)

    Shihab, S.; Thevenard, L.; Lemaître, A.; Gourdon, C.

    2017-04-01

    We excite perpendicular standing spin waves by a laser pulse in a GaMnAsP ferromagnetic layer and detect them using time-resolved magneto-optical effects. Quite counterintuitively, we find the first two excited modes to be of opposite chirality. We show that this can only be explained by taking into account absorption and optical phase shift inside the layer. This optical illusion is particularly strong in weakly absorbing layers. These results provide a correct identification of spin waves modes, enabling a trustworthy estimation of their respective weight as well as an unambiguous determination of the spin stiffness parameter.

  15. Performance of wave function and density functional methods for water hydrogen bond spin-spin coupling constants.

    Science.gov (United States)

    García de la Vega, J M; Omar, S; San Fabián, J

    2017-04-01

    Spin-spin coupling constants in water monomer and dimer have been calculated using several wave function and density functional-based methods. CCSD, MCSCF, and SOPPA wave functions methods yield similar results, specially when an additive approach is used with the MCSCF. Several functionals have been used to analyze their performance with the Jacob's ladder and a set of functionals with different HF exchange were tested. Functionals with large HF exchange appropriately predict 1 J O H , 2 J H H and 2h J O O couplings, while 1h J O H is better calculated with functionals that include a reduced fraction of HF exchange. Accurate functionals for 1 J O H and 2 J H H have been tested in a tetramer water model. The hydrogen bond effects on these intramolecular couplings are additive when they are calculated by SOPPA(CCSD) wave function and DFT methods. Graphical Abstract Evaluation of the additive effect of the hydrogen bond on spin-spin coupling constants of water using WF and DFT methods.

  16. Spin waves in ferromagnetic Tb/sub 0.76/Y/sub 0.24/

    International Nuclear Information System (INIS)

    Wakabayashi, N.; Nicklow, R.M.; Child, H.R.

    1978-01-01

    The conduction electron susceptibility chi (q) is considered to play an important role in the magnetism of rare-earth metals and alloys. In order to obtain information about chi (q), studies of the spin waves in the alloy Tb/sub 0.76/Y/sub 0.24/ have been carried out in a magnetic field. The magnetic structure of this alloy was found to remain spiral down to liquid helium temperature with zero field. The spin-wave dispersion curve in this structure has already been studied along the c*-direction, and the results were analyzed successfully in terms of a susceptibility function corresponding to a one-dimensional system with a slight modification. In order to obtain somewhat independent information about chi (q), the spin-wave dispersion curve for the ferromagnetic phase has been studied. A field of 14 kG was necessary to transform the structure into a ferromagnet at liquid helium temperature. Spin-wave energies which are calculated in terms of the susceptibility function determined from the measurements in the spiral structure agree rather well with the observed energies. A large damping and softening of the spin wave has been observed near the wave vector q=0.16 which characterized the spiral configuration. The origin of the phenomenon may be related to the instability of the ferromagnetic structure

  17. Self-generation and management of spin-electromagnetic wave solitons and chaos

    International Nuclear Information System (INIS)

    Ustinov, Alexey B.; Kondrashov, Alexandr V.; Nikitin, Andrey A.; Kalinikos, Boris A.

    2014-01-01

    Self-generation of microwave spin-electromagnetic wave envelope solitons and chaos has been observed and studied. For the investigation, we used a feedback active ring oscillator based on artificial multiferroic, which served as a nonlinear waveguide. We show that by increasing the wave amplification in the feedback ring circuit, a transition from monochromatic auto-generation to soliton train waveform and then to dynamical chaos occurs in accordance with the Ruelle-Takens scenario. Management of spin-electromagnetic-wave solitons and chaos parameters by both dielectric permittivity and magnetic permeability of the multiferroic waveguiding structure is demonstrated.

  18. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    International Nuclear Information System (INIS)

    Kryshtal, R.G.; Medved, A.V.

    2015-01-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined

  19. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    Energy Technology Data Exchange (ETDEWEB)

    Kryshtal, R.G.; Medved, A.V., E-mail: avm@ms.ire.rssi.ru

    2015-12-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined.

  20. Continuous wave protocol for simultaneous polarization and optical detection of P1-center electron spin resonance

    Science.gov (United States)

    Kamp, E. J.; Carvajal, B.; Samarth, N.

    2018-01-01

    The ready optical detection and manipulation of bright nitrogen vacancy center spins in diamond plays a key role in contemporary quantum information science and quantum metrology. Other optically dark defects such as substitutional nitrogen atoms (`P1 centers') could also become potentially useful in this context if they could be as easily optically detected and manipulated. We develop a relatively straightforward continuous wave protocol that takes advantage of the dipolar coupling between nitrogen vacancy and P1 centers in type 1b diamond to detect and polarize the dark P1 spins. By combining mutual spin flip transitions with radio frequency driving, we demonstrate the simultaneous optical polarization and detection of the electron spin resonance of the P1 center. This technique should be applicable to detecting and manipulating a broad range of dark spin populations that couple to the nitrogen vacancy center via dipolar fields, allowing for quantum metrology using these spin populations.

  1. Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

    Science.gov (United States)

    Farr, Will M; Stevenson, Simon; Miller, M Coleman; Mandel, Ilya; Farr, Ben; Vecchio, Alberto

    2017-08-23

    The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10 -7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

  2. Spin-wave resonances and surface spin pinning in Ga1-xMnxAs thin films

    Science.gov (United States)

    Bihler, C.; Schoch, W.; Limmer, W.; Goennenwein, S. T. B.; Brandt, M. S.

    2009-01-01

    We investigate the dependence of the spin-wave resonance (SWR) spectra of Ga0.95Mn0.05As thin films on the sample treatment. We find that for the external magnetic field perpendicular to the film plane, the SWR spectrum of the as-grown thin films and the changes upon etching and short-term hydrogenation can be quantitatively explained via a linear gradient in the uniaxial magnetic anisotropy field in growth direction. The model also qualitatively explains the SWR spectra observed for the in-plane easy-axis orientation of the external magnetic field. Furthermore, we observe a change in the effective surface spin pinning of the partially hydrogenated sample, which results from the tail in the hydrogen-diffusion profile. The latter leads to a rapidly changing hole concentration/magnetic anisotropy profile acting as a barrier for the spin-wave excitations. Therefore, short-term hydrogenation constitutes a simple method to efficiently manipulate the surface spin pinning.

  3. Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

    Directory of Open Access Journals (Sweden)

    D. Andrew Golter

    2016-12-01

    Full Text Available The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics.

  4. Design of a CMOS integrated on-chip oscilloscope for spin wave characterization

    Directory of Open Access Journals (Sweden)

    Eugen Egel

    2017-05-01

    Full Text Available Spin waves can perform some optically-inspired computing algorithms, e.g. the Fourier transform, directly than it is done with the CMOS logic. This article describes a new approach for on-chip characterization of spin wave based devices. The readout circuitry for the spin waves is simulated with 65-nm CMOS technology models. Commonly used circuits for Radio Frequency (RF receivers are implemented to detect a sinusoidal ultra-wideband (5-50 GHz signal with an amplitude of at least 15 μV picked up by a loop antenna. First, the RF signal is amplified by a Low Noise Amplifier (LNA. Then, it is down-converted by a mixer to Intermediate Frequency (IF. Finally, an Operational Amplifier (OpAmp brings the IF signal to higher voltages (50-300 mV. The estimated power consumption and the required area of the readout circuit is approximately 55.5 mW and 0.168 mm2, respectively. The proposed On-Chip Oscilloscope (OCO is highly suitable for on-chip spin wave characterization regarding the frequency, amplitude change and phase information. It offers an integrated low power alternative to current spin wave detecting systems.

  5. Research in magnetospheric wave phenomena

    International Nuclear Information System (INIS)

    Barfield, J.N.

    1975-01-01

    During the last 4 years a number of developments have occurred which have led to an increased understanding of the role of wave phenomena in the physical processes of the magnetosphere. While the studies span the frequency regime from millihertz to the electron gyrofrequency, the developments to be discussed in this paper have in common that they have added substantially to the understanding of the controlling processes, regions, and boundaries in the magnetosphere. The topics discussed are the increased awareness and documentation of the role of the plasmapause in micropulsation generation and propagation; the establishment of the role of ion cyclotron waves in the wave-particle interactions at the plasmapause; the discovery of magnetospheric electrostatic waves with ω = (3/2)Ω/sub -/; the discovery and preliminary identification of the source of plasmaspheric hiss; and the analysis of storm time Pc 5 waves as observed on the satellites ATS 1 and Explorer 45. (auth)

  6. Energy-imbalance mechanism of domain wall motion induced by propagation spin waves in finite magnetic nanostripe

    International Nuclear Information System (INIS)

    Zhu, Jinrong; Han, Zhaoyan; Su, Yuanchang; Hu, Jingguo

    2014-01-01

    The mechanism of the domain wall (DW) motions induced by spin wave in finite magnetic nanostripe is studied by micromagnetic simulations. We find that the spin-wave induced DM motions are always accompanied by an energy imbalance between two sides of the DW. The DW motion can be attributed to the expansion of the low-energy-density area and the contraction of the high-energy-density area. The energy imbalance strongly depends on whether the spin wave passes through the DW or is reflected by the DW. In the area of the spin wave propagation, the energy density increases with the time. However, in the superposition area of the incident spin wave and the reflected spin wave, the energy density decreases with the increasing of the time. It shows that this energy imbalance can be controlled by tuning the frequency of the spin wave. Finally, the effect of the damping parameter value is discussed. - Highlights: • The mechanism of the spin-wave induced DW motions is studied. • The spin-wave induced DW motions and the energy imbalance mechanism are given. • The DW motion with the same direction to that of SW is explained. • The DW motion with the opposite direction to that of SW is explained

  7. Observation of linear spin wave dispersion in the reentrant spin glass Fe sub 0 sub . sub 7 Al sub 0 sub . sub 3

    CERN Document Server

    Shapiro, S M; Raymond, S; Lee, S H; Motoya, K

    2002-01-01

    Fe sub 0 sub . sub 7 Al sub 0 sub . sub 3 is a reentrant spin glass, which undergoes a transition from a paramagnet to a disordered ferromagnet at T sub c propor to 500 K; at a lower temperature the spins progressively freeze and it exhibits a spin-glass-like behavior. In the ferromagnetic phase spin waves with a q sup 2 dispersion are observed at small q, which broaden rapidly and become diffusive beyond a critical wave vector q sub 0. On cooling the spin waves also disappear and a strong elastic central peak develops. For measurements around the (1,1,1) Bragg peak, a new sharp excitation is observed which has a linear dispersion behavior. It disappears above T sub c , but persists throughout the spin-glass phase. It is not present in the stoichiometric Fe sub 3 Al material. (orig.)

  8. Proceedings of RIKEN BNL Research Center workwhop on RHIC spin

    Energy Technology Data Exchange (ETDEWEB)

    SOFFER,J.

    1999-10-06

    This RHIC Spin Workshop is the 1999 annual meeting of the RHIC Spin Collaboration, and the second to be hosted at Brookhaven and sponsored by the RIKEN BNL Research Center. The previous meetings were at Brookhaven (1998), Marseille (1996), MIT in 1995, Argonne 1994, Tucson in 1991, and the Polarized Collider Workshop at Penn State in 1990. As noted last year, the Center provides a home for combined work on spin by theorists, experimenters, and accelerator physicists. This proceedings, as last year, is a compilation of 1 page summaries and 5 selected transparencies for each speaker. It is designed to be available soon after the workshop is completed. Speakers are welcome to include web or other references for additional material. The RHIC spin program and RHIC are rapidly becoming reality. RHIC has completed its first commissioning run, as described here by Steve Peggs. The first Siberian Snake for spin has been completed and is being installed in RHIC. A new polarized source from KEK and Triumf with over 1 milliampere of polarized H{sup minus} is being installed, described by Anatoli Zelenski. They have had a successful test of a new polarimeter for RHIC, described by Kazu Kurita and Haixin Huang. Spin commissioning is expected next spring (2000), and the first physics run for spin is anticipated for spring 2001. The purpose of the workshop is to get everyone together about once per year and discuss goals of the spin program, progress, problems, and new ideas. They also have many separate regular forums on spin. There are spin discussion sessions every Tuesday, now organized by Naohito Saito and Werner Vogelsang. The spin discussion schedule and copies of presentations are posted on http://riksg01.rhic.bnl.gov/rsc. Speakers and other spinners are encouraged to come to BNL and to lead a discussion on your favorite idea. They also have regular polarimeter and snake meetings on alternate Thursdays, led by Bill McGahern, the lead engineer for the accelerator spin

  9. Proceedings of RIKEN BNL Research Center workshop on RHIC spin

    International Nuclear Information System (INIS)

    Soffer, J.

    1999-01-01

    This RHIC Spin Workshop is the 1999 annual meeting of the RHIC Spin Collaboration, and the second to be hosted at Brookhaven and sponsored by the RIKEN BNL Research Center. The previous meetings were at Brookhaven (1998), Marseille (1996), MIT in 1995, Argonne 1994, Tucson in 1991, and the Polarized Collider Workshop at Penn State in 1990. As noted last year, the Center provides a home for combined work on spin by theorists, experimenters, and accelerator physicists. This proceedings, as last year, is a compilation of 1 page summaries and 5 selected transparencies for each speaker. It is designed to be available soon after the workshop is completed. Speakers are welcome to include web or other references for additional material. The RHIC spin program and RHIC are rapidly becoming reality. RHIC has completed its first commissioning run, as described here by Steve Peggs. The first Siberian Snake for spin has been completed and is being installed in RHIC. A new polarized source from KEK and Triumf with over 1 milliampere of polarized H minus is being installed, described by Anatoli Zelenski. They have had a successful test of a new polarimeter for RHIC, described by Kazu Kurita and Haixin Huang. Spin commissioning is expected next spring (2000), and the first physics run for spin is anticipated for spring 2001. The purpose of the workshop is to get everyone together about once per year and discuss goals of the spin program, progress, problems, and new ideas. They also have many separate regular forums on spin. There are spin discussion sessions every Tuesday, now organized by Naohito Saito and Werner Vogelsang. The spin discussion schedule and copies of presentations are posted on http://riksg01.rhic.bnl.gov/rsc. Speakers and other spinners are encouraged to come to BNL and to lead a discussion on your favorite idea. They also have regular polarimeter and snake meetings on alternate Thursdays, led by Bill McGahern, the lead engineer for the accelerator spin effort

  10. Ballistic transport of spin waves incident from cobalt leads across cobalt–gadolinium alloy nanojunctions

    International Nuclear Information System (INIS)

    Ashokan, V.; Abou Ghantous, M.; Ghader, D.; Khater, A.

    2014-01-01

    Calculations are presented for the scattering and ballistic transport of spin waves (SW) incident from cobalt leads, on ultrathin ferrimagnetic cobalt–gadolinium ‥Co][Co (1−c) Gd (c) ] ℓ [Co‥ nanojunction systems. The nanojunction [Co (1−c) Gd (c) ] ℓ itself is a randomly disordered alloy of thickness ℓ hcp lattice planes between matching hcp planes of the Co leads, at known stable concentrations c≤0.5 for this alloy system. To compute the spin dynamics, and the SW scattering and ballistic transport, this alloy nanojunction is modeled in the virtual crystal approximation (VCA), valid in particular at the length scale of the nanojunction for submicroscopic SW wavelengths. The phase field matching theory (PFMT) is applied to compute the localized and resonant magnons on the nanojunction. These magnons, characteristic of the embedded nanostructure, propagate in its symmetry plane with spin precession amplitudes that decay or match the spin wave states in the semi-infinite leads. The eigenvectors of these magnon modes are calculated for certain cases to illustrate the spin precession configurations on the nanojunction. The VCA-PFMT approach is also used to calculate the reflection and transmission spectra for the spin waves incident from the Co leads on the nanojunction. The results demonstrate resonance assisted maxima for the ballistic SW transmission spectra due to interactions between the incident spin waves and the nanojunction magnon modes. These properties are general for variable nanojunction thicknesses and alloy stable concentrations c≤0.5. In particular, the positions of the resonance assisted maxima of spin wave transmission can be modified with nanojunction thickness and alloy concentration. - Highlights: • Model is presented for spin wave scattering at CoGd disordered alloy nanojunctions. • Computations yield the localized and resonant magnon modes on the nanojunctions. • The spin waves ballistic reflection and transmission

  11. Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy

    Science.gov (United States)

    Mohseni, S. Morteza; Yazdi, H. F.; Hamdi, M.; Brächer, T.; Mohseni, S. Majid

    2018-03-01

    Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current.

  12. Eavesdropping on spin waves inside the domain-wall nanochannel via three-magnon processes

    Science.gov (United States)

    Zhang, Beining; Wang, Zhenyu; Cao, Yunshan; Yan, Peng; Wang, X. R.

    2018-03-01

    One recent breakthrough in the field of magnonics is the experimental realization of reconfigurable spin-wave nanochannels formed by a magnetic domain wall with a width of 10-100 nm [Wagner et al., Nat. Nano. 11, 432 (2016), 10.1038/nnano.2015.339]. This remarkable progress enables an energy-efficient spin-wave propagation with a well-defined wave vector along its propagating path inside the wall. In the mentioned experiment, a microfocus Brillouin light scattering spectroscopy was taken in a line-scans manner to measure the frequency of the bounded spin wave. Due to their localization nature, the confined spin waves can hardly be detected from outside the wall channel, which guarantees the information security to some extent. In this work, we theoretically propose a scheme to detect/eavesdrop on the spin waves inside the domain-wall nanochannel via nonlinear three-magnon processes. We send a spin wave (ωi,ki) in one magnetic domain to interact with the bounded mode (ωb,kb) in the wall, where kb is parallel with the domain-wall channel defined as the z ̂ axis. Two kinds of three-magnon processes, i.e., confluence and splitting, are expected to occur. The confluence process is conventional: conservation of energy and momentum parallel with the wall indicates a transmitted wave in the opposite domain with ω (k ) =ωi+ωb and (ki+kb-k ) .z ̂=0 , while the momentum perpendicular to the domain wall is not necessary to be conserved due to the nonuniform internal field near the wall. We predict a stimulated three-magnon splitting (or "magnon laser") effect: the presence of a bound magnon propagating along the domain wall channel assists the splitting of the incident wave into two modes, one is ω1=ωb,k1=kb identical to the bound mode in the channel, and the other one is ω2=ωi-ωb with (ki-kb-k2) .z ̂=0 propagating in the opposite magnetic domain. Micromagnetic simulations confirm our theoretical analysis. These results demonstrate that one is able to uniquely

  13. Splitting of standing spin-wave modes in circular submicron ferromagnetic dot under axial symmetry violation

    OpenAIRE

    Bunyaev, S. A.; Golub, V. O.; Salyuk, O. Yu.; Tartakovskaya, E. V.; Santos, N. M.; Timopheev, A. A.; Sobolev, N. A.; Serga, A. A.; Chumak, A. V.; Hillebrands, B.; Kakazei, G. N.

    2015-01-01

    The spin wave dynamics in patterned magnetic nanostructures is under intensive study during the last two decades. On the one hand, this interest is generated by new physics that can be explored in such structures. On the other hand, with the development of nanolithography, patterned nanoelements and their arrays can be used in many practical applications (magnetic recording systems both as media and read-write heads, magnetic random access memory, and spin-torque oscillators just to name a fe...

  14. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength.

    Science.gov (United States)

    Savochkin, I V; Jäckl, M; Belotelov, V I; Akimov, I A; Kozhaev, M A; Sylgacheva, D A; Chernov, A I; Shaposhnikov, A N; Prokopov, A R; Berzhansky, V N; Yakovlev, D R; Zvezdin, A K; Bayer, M

    2017-07-18

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with the spectrum of the optically generated spin waves. Here we tackle this problem by launching spin waves by a sequence of femtosecond laser pulses with pulse interval much shorter than the relaxation time of the magnetization oscillations. This leads to the cumulative phenomenon and allows us to generate magnons in a specific narrow range of wavenumbers. The wavelength of spin waves can be tuned from 15 μm to hundreds of microns by sweeping the external magnetic field by only 10 Oe or by slight variation of the pulse repetition rate. Our findings expand the capabilities of the optical spin pump-probe technique and provide a new method for the spin wave generation and control.

  15. Spin waves in full-polarized state of Dzyaloshinskii-Moriya helimagnets: Small-angle neutron scattering study

    Science.gov (United States)

    Grigoriev, S. V.; Sukhanov, A. S.; Altynbaev, E. V.; Siegfried, S.-A.; Heinemann, A.; Kizhe, P.; Maleyev, S. V.

    2015-12-01

    We develop the technique to study the spin-wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin-waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centered at the momentum transfer corresponding to the helix wave vector in helimagnetic phase ks, which is oriented along the applied magnetic field H . The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness A for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature Tc.

  16. Magnonic band structure, complete bandgap, and collective spin wave excitation in nanoscale two-dimensional magnonic crystals

    International Nuclear Information System (INIS)

    Kumar, D.; Barman, A.; Kłos, J. W.; Krawczyk, M.

    2014-01-01

    We present the observation of a complete bandgap and collective spin wave excitation in two-dimensional magnonic crystals comprised of arrays of nanoscale antidots and nanodots, respectively. Considering that the frequencies dealt with here fall in the microwave band, these findings can be used for the development of suitable magnonic metamaterials and spin wave based signal processing. We also present the application of a numerical procedure, to compute the dispersion relations of spin waves for any high symmetry direction in the first Brillouin zone. The results obtained from this procedure have been reproduced and verified by the well established plane wave method for an antidot lattice, when magnetization dynamics at antidot boundaries are pinned. The micromagnetic simulation based method can also be used to obtain iso–frequency contours of spin waves. Iso–frequency contours are analogous of the Fermi surfaces and hence, they have the potential to radicalize our understanding of spin wave dynamics. The physical origin of bands, partial and full magnonic bandgaps have been explained by plotting the spatial distribution of spin wave energy spectral density. Although, unfettered by rigid assumptions and approximations, which afflict most analytical methods used in the study of spin wave dynamics, micromagnetic simulations tend to be computationally demanding. Thus, the observation of collective spin wave excitation in the case of nanodot arrays, which can obviate the need to perform simulations, may also prove to be valuable

  17. Measuring the spin of black holes in binary systems using gravitational waves.

    Science.gov (United States)

    Vitale, Salvatore; Lynch, Ryan; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-06-27

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries.

  18. High energy spin waves in iron measured by neutron scattering

    International Nuclear Information System (INIS)

    Boothroyd, A.T.; Paul, D.M.; Mook, H.A.

    1991-01-01

    We present new results for the spin were dispersion relation measured along the [ζζ0] direction in bcc iron (12% silicon) by time-of-flight, neutron inelastic scattering. The excitations were followed to the zone boundary, where they are spread over a range of energies around 300meV. 6 refs., 2 figs

  19. Spin wave differential circuit for realization of thermally stable magnonic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Taichi, E-mail: goto@ee.tut.ac.jp; Kanazawa, Naoki; Buyandalai, Altansargai; Takagi, Hiroyuki; Nakamura, Yuichi; Inoue, Mitsuteru [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibari-Ga-Oka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Okajima, Shingo; Hasegawa, Takashi [Murata Manufacturing Co., Ltd., Kyoto 617-8555 (Japan); Granovsky, Alexander B. [Faculty of Physics, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Sekiguchi, Koji [Department of Physics, Keio University, Yokohama 223-8522 (Japan); JST-PRESTO, Kawaguchi, Saitama 332-0012 (Japan); Ross, Caroline A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

    2015-03-30

    A magnetic-field sensor with a high sensitivity of 38 pT/Hz was demonstrated. By utilizing a spin-wave differential circuit (SWDC) using two yttrium iron garnet (YIG) films, the temperature sensitivity was suppressed, and the thermal stability of the phase of the spin waves was −0.0095° K{sup −1}, which is three orders of magnitude better than a simple YIG-based sensor, ∼20° K{sup −1}. The SWDC architecture opens the way to design YIG-based magnonic devices.

  20. Spin wave differential circuit for realization of thermally stable magnonic sensors

    International Nuclear Information System (INIS)

    Goto, Taichi; Kanazawa, Naoki; Buyandalai, Altansargai; Takagi, Hiroyuki; Nakamura, Yuichi; Inoue, Mitsuteru; Okajima, Shingo; Hasegawa, Takashi; Granovsky, Alexander B.; Sekiguchi, Koji; Ross, Caroline A.

    2015-01-01

    A magnetic-field sensor with a high sensitivity of 38 pT/Hz was demonstrated. By utilizing a spin-wave differential circuit (SWDC) using two yttrium iron garnet (YIG) films, the temperature sensitivity was suppressed, and the thermal stability of the phase of the spin waves was −0.0095° K −1 , which is three orders of magnitude better than a simple YIG-based sensor, ∼20° K −1 . The SWDC architecture opens the way to design YIG-based magnonic devices

  1. Bias-free spin-wave phase shifter for magnonic logic

    Energy Technology Data Exchange (ETDEWEB)

    Louis, Steven; Tyberkevych, Vasyl; Slavin, Andrei [Department of Physics, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan, 48309–4401 (United States); Lisenkov, Ivan, E-mail: ivan.lisenkov@phystech.edu [Department of Physics, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan, 48309–4401 (United States); Kotelnikov Institute of Radio-engineering and Electronics of RAS, 11–7 Mokhovaya st., Moscow, 125009 (Russian Federation); Nikitov, Sergei [Kotelnikov Institute of Radio-engineering and Electronics of RAS, 11–7 Mokhovaya st., Moscow, 125009 (Russian Federation); Moscow Institute of Physics and Technology, 9 Instituskij per., Dolgoprudny, 141700, Moscow Region (Russian Federation); Department of Physics, Saratov State University, 83 Astrakhanskaya Street, Saratov, 410012 (Russian Federation)

    2016-06-15

    A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall “waveguide” in a dipolarly-coupled magnetic dot array with a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that the remagnetization of a single magnetic dot adjacent to the domain wall waveguide introduces a controllable phase shift in the propagating spin wave mode without significant change to the mode amplitude. It is also demonstrated that a logic XOR gate can be realized in the same system.

  2. Glass transition in the spin-density wave phase of (TMTSF)2PF6

    DEFF Research Database (Denmark)

    Lasjaunias, J.C.; Biljakovic, K.; Nad, F.

    1994-01-01

    We present the results of low frequency dielectric measurements and a detailed kinetic investigation of the specific heat anomaly in the spin-density wave phase of (TMTSF)(2)PF6 in the temperature range between 2 and 4 K. The dielectric relaxation shows a critical slowing down towards a ''static'......'' glass transition around 2 K. The jump in the specific heat in different controlled kinetic conditions shows all the characteristics of freezing in supercooled liquids. Both effects give direct evidence of a glass transition in the spin-density wave ground state....

  3. The phase accumulation and antenna near field of microscopic propagating spin wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Crosby S.; Kostylev, Mikhail, E-mail: mikhail.kostylev@uwa.edu.au; Ivanov, Eugene [School of Physics M013, The University of Western Australia, Crawley, WA 6009 (Australia); Ding, Junjia; Adeyeye, Adekunle O. [Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore (Singapore)

    2014-01-20

    We studied phase accumulation by the highly non-reciprocal magnetostatic surface spin waves in thin Permalloy microstripes excited and received by microscopic coplanar antennae. We find that the experimentally measured characteristic length of the near field of the antenna is smaller than the total width of the coplanar. This is confirmed by our numerical simulations. Consequently, the distance over which the spin wave accumulates its phase while travelling between the input and output antennae coincides with the distance between the antennae symmetry axes with good accuracy.

  4. The phase accumulation and antenna near field of microscopic propagating spin wave devices

    International Nuclear Information System (INIS)

    Chang, Crosby S.; Kostylev, Mikhail; Ivanov, Eugene; Ding, Junjia; Adeyeye, Adekunle O.

    2014-01-01

    We studied phase accumulation by the highly non-reciprocal magnetostatic surface spin waves in thin Permalloy microstripes excited and received by microscopic coplanar antennae. We find that the experimentally measured characteristic length of the near field of the antenna is smaller than the total width of the coplanar. This is confirmed by our numerical simulations. Consequently, the distance over which the spin wave accumulates its phase while travelling between the input and output antennae coincides with the distance between the antennae symmetry axes with good accuracy

  5. Experimental methods of shock wave research

    CERN Document Server

    Seiler, Friedrich

    2016-01-01

    This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.

  6. Hybrid excitations due to crystal field, spin-orbit coupling, and spin waves in LiFePO4

    Science.gov (United States)

    Yiu, Yuen; Le, Manh Duc; Toft-Peterson, Rasmus; Ehlers, Georg; McQueeney, Robert J.; Vaknin, David

    2017-03-01

    We report on the spin waves and crystal field excitations in single crystal LiFePO4 by inelastic neutron scattering over a wide range of temperatures, below and above the antiferromagnetic transition of this system. In particular, we find extra excitations below TN=50 K that are nearly dispersionless and are most intense around magnetic zone centers. We show that these excitations correspond to transitions between thermally occupied excited states of Fe2 + due to splitting of the S =2 levels that arise from the crystal field and spin-orbit interactions. These excitations are further amplified by the highly distorted nature of the oxygen octahedron surrounding the iron atoms. Above TN, magnetic fluctuations are observed up to at least 720 K, with an additional inelastic excitation around 4 meV, which we attribute to single-ion effects, as its intensity weakens slightly at 720 K compared to 100 K, which is consistent with the calculated cross sections using a single-ion model. Our theoretical analysis, using the MF-RPA model, provides both detailed spectra of the Fe d shell and estimates of the average ordered magnetic moment and TN. By applying the MF-RPA model to a number of existing spin-wave results from other Li M PO4 (M =Mn , Co, and Ni), we are able to obtain reasonable predictions for the moment sizes and transition temperatures.

  7. Toward nonlinear magnonics: Intensity-dependent spin-wave switching in insulating side-coupled magnetic stripes

    Science.gov (United States)

    Sadovnikov, A. V.; Odintsov, S. A.; Beginin, E. N.; Sheshukova, S. E.; Sharaevskii, Yu. P.; Nikitov, S. A.

    2017-10-01

    We demonstrate that the nonlinear spin-wave transport in two laterally parallel magnetic stripes exhibit the intensity-dependent power exchange between the adjacent spin-wave channels. By the means of Brillouin light scattering technique, we investigate collective nonlinear spin-wave dynamics in the presence of magnetodipolar coupling. The nonlinear intensity-dependent effect reveals itself in the spin-wave mode transformation and differential nonlinear spin-wave phase shift in each adjacent magnetic stripe. The proposed analytical theory, based on the coupled Ginzburg-Landau equations, predicts the geometry design involving the reduction of power requirement to the all-magnonic switching. A very good agreement between calculation and experiment was found. In addition, a micromagnetic and finite-element approach has been independently used to study the nonlinear behavior of spin waves in adjacent stripes and the nonlinear transformation of spatial profiles of spin-wave modes. Our results show that the proposed spin-wave coupling mechanism provides the basis for nonlinear magnonic circuits and opens the perspectives for all-magnonic computing architecture.

  8. Spin wave isolator based on frequency displacement nonreciprocity in ferromagnetic bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Shichi, Shinsuke, E-mail: shinsuke-shichi@murata.com; Matsuda, Kenji; Okajima, Shingo; Hasegawa, Takashi; Okada, Takekazu [Murata Manufacturing Co., Ltd., Kyoto 617-8555 (Japan); Kanazawa, Naoki; Goto, Taichi, E-mail: goto@ee.tut.ac.jp; Takagi, Hiroyuki; Inoue, Mitsuteru [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibari-Ga-Oka, Tempaku, Toyohashi, Aichi 441-8580 (Japan)

    2015-05-07

    We demonstrated the spin wave isolator using bilayer ferromagnetic media comprising single crystalline and poly-crystalline yttrium iron garnet films, which can control the propagation frequency of magnetostatic waves by the direction of applied magnetic field. This isolator's property does not depend on their thickness then this can be downsized and integrated for nano-scale magnonic circuits. Calculated dispersion relationship shows good agreement with measured one.

  9. The technique of the modified hamiltonian for construction of the spin-projected wave function

    International Nuclear Information System (INIS)

    Tsaune, A.Ya.; Glushkov, V.N.

    1991-01-01

    A method is suggested to construct the wave function, which is an eigenfunction for operator S 2 . A combination of Lowdin's projection operators and the method of taking into account the orthogonality conditions in variational problems previously developed by the authors is used for determination of the spin-current wave functions component. It is shown that the suggested method gives better results for the energies that the traditional restricted Hartee-Fock scheme

  10. All optical detection of picosecond spin-wave dynamics in 2D annular antidot lattice

    Science.gov (United States)

    Porwal, Nikita; Mondal, Sucheta; Choudhury, Samiran; De, Anulekha; Sinha, Jaivardhan; Barman, Anjan; Datta, Prasanta Kumar

    2018-02-01

    Novel magnetic structures with precisely controlled dimensions and shapes at the nanoscale have potential applications in spin logic, spintronics and other spin-based communication devices. We report the fabrication of 2D bi-structure magnonic crystal in the form of embedded nanodots in a periodic Ni80Fe20 antidot lattice structure (annular antidot) by focused ion-beam lithography. The spin-wave spectra of the annular antidot sample, studied for the first time by a time-resolved magneto-optic Kerr effect microscopy show a remarkable variation with bias field, which is important for the above device applications. The optically induced spin-wave spectra show multiple modes in the frequency range 14.7 GHz-3.5 GHz due to collective interactions between the dots and antidots as well as the annular elements within the whole array. Numerical simulations qualitatively reproduce the experimental results, and simulated mode profiles reveal the spatial distribution of the spin-wave modes and internal magnetic fields responsible for these observations. It is observed that the internal field strength increases by about 200 Oe inside each dot embedded within the hole of annular antidot lattice as compared to pure antidot lattice and pure dot lattice. The stray field for the annular antidot lattice is found to be significant (0.8 kOe) as opposed to the negligible values of the same for the pure dot lattice and pure antidot lattice. Our findings open up new possibilities for development of novel artificial crystals.

  11. Breakdown of Spin-Waves in Anisotropic Magnets: Spin Dynamics in α-RuCl3

    Science.gov (United States)

    Winter, Stephen; Riedl, Kira; Honecker, Andreas; Valenti, Roser

    α -RuCl3 has recently emerged as a promising candidate for realizing the hexagonal Kitaev model in a real material. Similar to the related iridates (e.g. Na2IrO3), complex magnetic interactions arise from a competition between various similar energy scales, including spin-orbit coupling (SOC), Hund's coupling, and crystal-field splitting. Due to this complexity, the correct spin Hamiltonians for such systems remain hotly debated. For α-RuCl3, a combination of ab-initio calculations, microscopic considerations, and analysis of the static magnetic response have suggested off-diagonal couplings (Γ ,Γ') and long-range interactions in addition to the expected Kitaev exchange. However, the effect of such additional terms on the dynamic response remains unclear. In this contribution, we discuss the recently measured inelastic neutron scattering response in the context of realistic proposals for the microscopic spin Hamiltonian. We conclude that the observed scattering continuum, which has been taken as a signature of Kitaev spin liquid physics, likely persists over a broad range of parameters.

  12. Partial wave expansions for arbitrary spin and the role of non-central forces

    International Nuclear Information System (INIS)

    Johnson, R.C.

    1976-09-01

    The partial wave expansion of the amplitudes used by Hooton and Johnson for the scattering of particles of arbitrary spin is derived. A discussion is given of the extent to which effects arising from transition matrix elements that are diagonal and nondiagonal in orbital angular momentum can be distinguished in observables

  13. Imaging of propagation dynamics of optically-excited spin waves in a garnet film

    International Nuclear Information System (INIS)

    Hashimoto, Yusuke; Saitoh, Eiji

    2016-01-01

    We demonstrate the direct imaging of the propagation dynamics of the optically-excited spin waves in a garnet film observed with an all-optical pump-and-probe magneto-optical imaging technique having sub-pico second time-resolution, sub-micrometer spatial resolution, and milli-degrees of accuracy in the rotation angle of the light polarization. (author)

  14. Partial wave expansions for arbitrary spin and the role of non-central forces

    International Nuclear Information System (INIS)

    Johnson, R.C.

    1977-01-01

    The partial wave expansion of the amplitudes used by Hooton and Johnson for the scattering of particles of arbitrary spin is derived. A discussion is given of the extent to which effects arising from transition matrix elements that are diagonal and non-diagonal in orbital angular momentum can be distinguished in observables. (Auth.)

  15. Ground eigenvalue and eigenfunction of a spin-weighted spheroidal wave equation in low frequencies

    Institute of Scientific and Technical Information of China (English)

    Tang Wen-Lin; Tian Gui-Hua

    2011-01-01

    Spin-weighted spheroidal wave functions play an important role in the study of the linear stability of rotating Kerr black holes and are studied by the perturbation method in supersymmetric quantum mechanics. Their analytic ground eigenvalues and eigenfunctions are obtained by means of a series in low frequency. The ground eigenvalue and eigenfunction for small complex frequencies are numerically determined.

  16. Universal relations for spin-orbit-coupled Fermi gas near an s -wave resonance

    Science.gov (United States)

    Zhang, Pengfei; Sun, Ning

    2018-04-01

    Synthetic spin-orbit-coupled quantum gases have been widely studied both experimentally and theoretically in the past decade. As shown in previous studies, this modification of single-body dispersion will in general couple different partial waves of the two-body scattering and thus distort the wave function of few-body bound states which determines the short-distance behavior of many-body wave function. In this work, we focus on the two-component Fermi gas with one-dimensional or three-dimensional spin-orbit coupling (SOC) near an s -wave resonance. Using the method of effective field theory and the operator product expansion, we derive universal relations for both systems, including the adiabatic theorem, viral theorem, and pressure relation, and obtain the momentum distribution matrix 〈ψa†(q ) ψb(q ) 〉 at large q (a ,b are spin indices). The momentum distribution matrix shows both spin-dependent and spatial anisotropic features. And the large momentum tail is modified at the subleading order thanks to the SOC. We also discuss the experimental implication of these results depending on the realization of the SOC.

  17. The influence of boundary conditions on domain structure stability in spin wave approximation

    International Nuclear Information System (INIS)

    Wachinewski, A.

    1974-01-01

    Instead of the usually used Born-Karman cyclic conditions, boundary conditions which take into account the situation of the boundary lattice sites lying on the crystal's surface are assumed. It is shown that the particular choice of the boundary conditions secures the stability of domain structure in ferromagnet (positive spin wave energies), without including the Winter term in Hamiltonian. (author)

  18. Ferroelectricity Induced by Acentric Spin-Density Waves in YMn2O5

    NARCIS (Netherlands)

    Chapon, L.C.; Radaelli, P.G.; Blake, G.R.; Park, S.; Cheong, S.-W.

    2006-01-01

    The commensurate and incommensurate magnetic structures of the magnetoelectric system YMn2O5, as determined from neutron diffraction, were found to be spin-density waves lacking a global center of symmetry. We propose a model, based on a simple magnetoelastic coupling to the lattice, which enables

  19. Effects of the magnetic field variation on the spin wave interference in a magnetic cross junction

    Science.gov (United States)

    Balynskiy, M.; Chiang, H.; Kozhevnikov, A.; Dudko, G.; Filimonov, Y.; Balandin, A. A.; Khitun, A.

    2018-05-01

    This article reports results of the investigation of the effect of the external magnetic field variation on the spin wave interference in a magnetic cross junction. The experiments were performed using a micrometer scale Y3Fe5O12 cross structure with a set of micro-antennas fabricated on the edges of the cross arms. Two of the antennas were used for the spin wave excitation while a third antenna was used for detecting the inductive voltage produced by the interfering spin waves. It was found that a small variation of the bias magnetic field may result in a significant change of the output inductive voltage. The effect is most prominent under the destructive interference condition. The maximum response exceeds 30 dB per 0.1 Oe at room temperature. It takes a relatively small bias magnetic field variation of about 1 Oe to drive the system from the destructive to the constructive interference conditions. The switching is accompanied by a significant, up to 50 dB, change in the output voltage. The obtained results demonstrate a feasibility of the efficient spin wave interference control by an external magnetic field, which may be utilized for engineering novel type of magnetometers and magnonic logic devices.

  20. Unidirectional Spin-Wave-Propagation-Induced Seebeck Voltage in a PEDOT:PSS/YIG Bilayer

    Science.gov (United States)

    Wang, P.; Zhou, L. F.; Jiang, S. W.; Luan, Z. Z.; Shu, D. J.; Ding, H. F.; Wu, D.

    2018-01-01

    We clarify the physical origin of the dc voltage generation in a bilayer of a conducting polymer film and a micrometer-thick magnetic insulator Y3Fe5O12 (YIG) film under ferromagnetic resonance and/or spin wave excitation conditions. The previous attributed mechanism, the inverse spin Hall effect in the polymer [Nat. Mater. 12, 622 (2013), 10.1038/nmat3634], is excluded by two control experiments. We find an in-plane temperature gradient in YIG which has the same angular dependence with the generated voltage. Both vanish when the YIG thickness is reduced to a few nanometers. Thus, we argue that the dc voltage is governed by the Seebeck effect in the polymer, where the temperature gradient is created by the nonreciprocal magnetostatic surface spin wave propagation in YIG.

  1. Generalized spin-wave theory: Application to the bilinear-biquadratic model

    Science.gov (United States)

    Muniz, Rodrigo A.; Kato, Yasuyuki; Batista, Cristian D.

    2014-08-01

    We present a mathematical framework for the multi-boson approach that has been used several times for treating spin systems. We demonstrate that the multi-boson approach corresponds to a generalization of the traditional spin-wave theory from SU(2) to SU(N), where N is the number of states of the local degree of freedom. Low-energy excitations are waves of the local order parameter that fluctuates in the SU(N) space of unitary transformations of the local spin states, instead of the SU(2) space of local spin rotations. Since the generators of the SU(N) group can be represented as bilinear forms in N-flavored bosons, the low-energy modes of the generalized spin-wave theory (GSWT) are described with N-1 different bosons, which provide a more accurate description of low-energy excitations even for the usual ferromagnetic and antiferromagnetic phases. The generalization enables the treatment of quantum spin systems whose ground states exhibit multipolar ordering as well as the detection of instabilities of magnetically ordered states (dipolar ordering) towards higher multipolar orderings. We illustrate the advantages of the GSWT by applying it to a bilinear-biquadratic model of arbitrary spin S on hypercubic lattices, and then analyzing the spectrum of dipolar phases in order to find their instabilities. In contrast to the known results for S=1 when the biquadratic term in the Hamiltonian is negative, we find that there is no nematic phase between the ferromagnetic or antiferromagnetic orderings for S>1.

  2. Fermi wave vector for the partially spin-polarized composite-fermion Fermi sea

    Science.gov (United States)

    Balram, Ajit C.; Jain, J. K.

    2017-12-01

    The fully spin-polarized composite-fermion (CF) Fermi sea at the half-filled lowest Landau level has a Fermi wave vector kF*=√{4 π ρe } , where ρe is the density of electrons or composite fermions, supporting the notion that the interaction between composite fermions can be treated perturbatively. Away from ν =1 /2 , the area is seen to be consistent with kF*=√{4 π ρe } for ν 1 /2 , where ρh is the density of holes in the lowest Landau level. This result is consistent with particle-hole symmetry in the lowest Landau level. We investigate in this article the Fermi wave vector of the spin-singlet CF Fermi sea (CFFS) at ν =1 /2 , for which particle-hole symmetry is not a consideration. Using the microscopic CF theory, we find that for the spin-singlet CFFS the Fermi wave vectors for up- and down-spin CFFSs at ν =1 /2 are consistent with kF*↑,↓=√{4 π ρe↑,↓ } , where ρe↑=ρe↓=ρe/2 , which implies that the residual interactions between composite fermions do not cause a nonperturbative correction for spin-singlet CFFS either. Our results suggest the natural conjecture that for arbitrary spin polarization the CF Fermi wave vectors are given by kF*↑=√{4 π ρe↑ } and kF*↓=√{4 π ρe↓ } .

  3. Linear spin-wave theory of incommensurably modulated magnets

    DEFF Research Database (Denmark)

    Ziman, Timothy; Lindgård, Per-Anker

    1986-01-01

    Calculations of linearized theories of spin dynamics encounter difficulties when applied to incommensurable magnetic phases: lack of translational invariance leads to an infinite coupled system of equations. The authors resolve this for the case of a `single-Q' structure by mapping onto the problem......: at higher frequency there appear bands of response sharply defined in frequency, but broad in momentum transfer; at low frequencies there is a response maximum at the q vector corresponding to the modulation vector. They discuss generalizations necessary for application to rare-earth magnets...

  4. Spin effects in nonlinear Compton scattering in a plane-wave laser pulse

    International Nuclear Information System (INIS)

    Boca, Madalina; Dinu, Victor; Florescu, Viorica

    2012-01-01

    We study theoretically the electron angular and energy distribution in the non-linear Compton effect in a finite plane-wave laser pulse. We first present analytical and numerical results for unpolarized electrons (described by a Volkov solution of the Dirac equation), in comparison with those corresponding to a spinless particle (obeying the Klein–Gordon equation). Then, in the spin 1/2 case, we include results for the spin flip probability. The regime in which the spin effects are negligible, i.e. the results for the unpolarized spin 1/2 particle coincide practically with those for the spinless particle, is the same as the regime in which the emitted radiation is well described by classical electrodynamics.

  5. Holocaust survivors: three waves of resilience research.

    Science.gov (United States)

    Greene, Roberta R; Hantman, Shira; Sharabi, Adi; Cohen, Harriet

    2012-01-01

    Three waves of resilience research have resulted in resilience-enhancing educational and therapeutic interventions. In the first wave of inquiry, researchers explored the traits and environmental characteristics that enabled people to overcome adversity. In the second wave, researchers investigated the processes related to stress and coping. In the third wave, studies examined how people grow and are transformed following adverse events, often leading to self-actualize, client creativity and spirituality. In this article the authors examined data from a study, "Forgiveness, Resiliency, and Survivorship among Holocaust Survivors" funded by the John Templeton Foundation ( Greene, Armour, Hantman, Graham, & Sharabi, 2010 ). About 65% of the survivors scored on the high side for resilience traits. Of the survivors, 78% engaged in processes considered resilient and felt they were transcendent or had engaged in behaviors that help them grow and change over the years since the Holocaust, including leaving a legacy and contributing to the community.

  6. 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.

  7. Beating the Spin-Down Limit on Gravitational Wave Emission from the Crab Pulsar

    International Nuclear Information System (INIS)

    Abbott, B.; Babak, S.; Abbott, R.; Adhikari, R.; Anderson, S. B.; Araya, M.; Armandula, H.; Ballmer, S.; Ajith, P.; Allen, B.; Aulbert, C.; Allen, G.; Amin, R.; Anderson, W. G.; Armor, P.; Arain, M. A.; Aso, Y.; Aston, S.; Aufmuth, P.; Bantilan, H.

    2008-01-01

    We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first 9 months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret our results in the context of two possible gravitational wave emission mechanisms.

  8. Template banks to search for compact binaries with spinning components in gravitational wave data

    International Nuclear Information System (INIS)

    Van Den Broeck, Chris; Cokelaer, Thomas; Harry, Ian; Jones, Gareth; Sathyaprakash, B. S.; Brown, Duncan A.; Tagoshi, Hideyuki; Takahashi, Hirotaka

    2009-01-01

    Gravitational waves from coalescing compact binaries are one of the most promising sources for detectors such as LIGO, Virgo, and GEO600. If the components of the binary possess significant angular momentum (spin), as is likely to be the case if one component is a black hole, spin-induced precession of a binary's orbital plane causes modulation of the gravitational-wave amplitude and phase. If the templates used in a matched-filter search do not accurately model these effects then the sensitivity, and hence the detection rate, will be reduced. We investigate the ability of several search pipelines to detect gravitational waves from compact binaries with spin. We use the post-Newtonian approximation to model the inspiral phase of the signal and construct two new template banks using the phenomenological waveforms of Buonanno, Chen, and Vallisneri [A. Buonanno, Y. Chen, and M. Vallisneri, Phys. Rev. D 67, 104025 (2003)]. We compare the performance of these template banks to that of banks constructed using the stationary phase approximation to the nonspinning post-Newtonian inspiral waveform currently used by LIGO and Virgo in the search for compact binary coalescence. We find that, at the same false alarm rate, a search pipeline using phenomenological templates is no more effective than a pipeline which uses nonspinning templates. We recommend the continued use of the nonspinning stationary phase template bank until the false alarm rate associated with templates which include spin effects can be substantially reduced.

  9. Spin-wave stiffness in the Dzyaloshinskii-Moriya helimagnets Mn1 -xFexSi

    Science.gov (United States)

    Grigoriev, S. V.; Altynbaev, E. V.; Siegfried, S.-A.; Pschenichnyi, K. A.; Menzel, D.; Heinemann, A.; Chaboussant, G.

    2018-01-01

    The small-angle neutron scattering is used to measure the spin-wave stiffness in the field-polarized state of the Dzyaloshinskii-Moriya helimagnets Mn1 -xFexSi with x =0.03 , 0.06, 0.09, and 0.10. The Mn1 -xFexSi compounds are helically ordered below Tc and show a helical fluctuation regime above Tc in a wide range up to TDM. The critical temperatures Tc and TDM decrease with x and tend to 0 at x =0.11 and 0.17, respectively. We have found that the spin-wave stiffness A change weakly with temperature for each individual Fe-doped compound. On the other hand, the spin-wave stiffness A decreases with x duplicating the TDM dependence on x , rather than Tc(x ) . These findings classify the thermal phase transition in all Mn1 -xFexSi compounds as an abrupt change in the spin state caused, most probably, by the features of an electronic band structure. Moreover, the criticality in these compounds is not related to the value of the ferromagnetic interaction but demonstrates the remarkable role of the Dzyaloshinskii-Moriya interaction as a factor destabilizing the magnetic order.

  10. Modulated spin waves and robust quasi-solitons in classical Heisenberg rings

    International Nuclear Information System (INIS)

    Schmidt, Heinz-Juergen; Schroeder, Christian; Luban, Marshall

    2011-01-01

    We investigate the dynamical behavior of finite rings of classical spin vectors interacting via nearest-neighbor isotropic exchange in an external magnetic field. Our approach is to utilize the solutions of a continuum version of the discrete spin equations of motion (EOM) which we derive by assuming continuous modulations of spin wave solutions of the EOM for discrete spins. This continuum EOM reduces to the Landau-Lifshitz equation in a particular limiting regime. The usefulness of the continuum EOM is demonstrated by the fact that the time-evolved numerical solutions of the discrete spin EOM closely track the corresponding time-evolved solutions of the continuum equation. It is of special interest that our continuum EOM possesses soliton solutions, and we find that these characteristics are also exhibited by the corresponding solutions of the discrete EOM. The robustness of solitons is demonstrated by considering cases where initial states are truncated versions of soliton states and by numerical simulations of the discrete EOM equations when the spins are coupled to a heat bath at finite temperatures. (paper)

  11. Comparison of continuous wave, spin echo, and rapid scan EPR of irradiated fused quartz

    International Nuclear Information System (INIS)

    Mitchell, Deborah G.; Quine, Richard W.; Tseitlin, Mark; Meyer, Virginia; Eaton, Sandra S.; Eaton, Gareth R.

    2011-01-01

    The E' defect in irradiated fused quartz has spin lattice relaxation times (T 1 ) about 100-300 μs and spin-spin relaxation times (T 2 ) up to about 200 μs, depending on the concentration of defects and other species in the sample. These long relaxation times make it difficult to record an unsaturated continuous wave (CW) electron paramagnetic resonance (EPR) signal that is free of passage effects. Signals measured at X-band (∼9.5 GHz) by three EPR methods: conventional slow-scan field-modulated EPR, rapid scan EPR, and pulsed EPR, were compared. To acquire spectra with comparable signal-to-noise, both pulsed and rapid scan EPR require less time than conventional CW EPR. Rapid scan spectroscopy does not require the high power amplifiers that are needed for pulsed EPR. The pulsed spectra, and rapid scan spectra obtained by deconvolution of the experimental data, are free of passage effects.

  12. Spin-wave resonance in magnetic films in conditions of skin effect

    International Nuclear Information System (INIS)

    Nosov, R.N.; Sementsov, D.I.

    2002-01-01

    The effect of the finite depth of the high-frequency field penetration into the ferromagnetic metal on the spin-wave resonance spectrum perpendicular to the magnetized layer with different types of the spins surface fixation and by availability of attenuation in the spin system is studied. The exact numerical solution of the magnetization motion equation with an account of the skin-layer finite thickness is obtained. The change in the form of the resonance curve on the frequencies close to the frequency of the ferromagnetic resonance is identified in the case of essentially nonuniform high-frequency field distribution by the layer thickness along with widening and decreasing in the amplitude of all resonance peaks [ru

  13. 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.

  14. Do spin-off companies make academics' heads spin? The impacts of research-based spin-off companies on the production of scientific knowledge

    NARCIS (Netherlands)

    Zomer, A.H.

    2011-01-01

    Public research organisations nowadays are very much involved in the commercialisation of their research results, especially by creating spin-off companies. Government generally views research commercialisation as an important driver of innovation and as an opportunity to supplement increasingly

  15. Spin dynamics and implications for superconductivity. Some problems with the d-wave scenario

    International Nuclear Information System (INIS)

    Levin, K.; Zha, Y.; Radtke, R.J.; Si, Q.; Norman, M.R.; Schuettler, H.B.

    1994-01-01

    We review the spin dynamics of the normal state of the cuprates with special emphasis on neutron data in both the YBa 2 Cu 3 O 7-δ and La 2-x Sr x CuO 4 systems. When realistic models of the Fermi surface shapes are incorporated, along with a moderate degree of spin fluctuations, we find good semiquantitative agreement with experiment for both cuprates. Building on the success of this Fermi-liquid-based scheme, we explore the implications for d-wave pairing from a number of vantage points. We conclude that our present experimental and theoretical understanding is inadequate to confirm or refute the d-wave scenario. 26 refs., 6 figs

  16. Coherent storage of temporally multimode light using a spin-wave atomic frequency comb memory

    International Nuclear Information System (INIS)

    Gündoğan, M; Mazzera, M; Ledingham, P M; Cristiani, M; De Riedmatten, H

    2013-01-01

    We report on the coherent and multi-temporal mode storage of light using the full atomic frequency comb memory scheme. The scheme involves the transfer of optical atomic excitations in Pr 3+ :Y 2 SiO 5 to spin waves in hyperfine levels using strong single-frequency transfer pulses. Using this scheme, a total of five temporal modes are stored and recalled on-demand from the memory. The coherence of the storage and retrieval is characterized using a time-bin interference measurement resulting in visibilities higher than 80%, independent of the storage time. This coherent and multimode spin-wave memory is promising as a quantum memory for light. (paper)

  17. Relativistic wave functions of two spin 1/2 quarks in a model with QCD interaction

    International Nuclear Information System (INIS)

    Skachkov, N.B.; Solovtsov, I.L.

    1981-01-01

    Within the hamiltonian formulation of quantum field theory an equation is obtained for the vertex and wave functions of a composite system of two spin 1/2 quarks. Exact solutions are found for the relativistic potential having in the momentum representation the ''asymptotically-free'' behaviour at large values of momentum transfer Q 2 . It is shown that within the given model the π-meson wave function has zero at a finite distance corresponding to the point of discontinuity of the effective potential [ru

  18. Collective spin waves on a nanowire array with step-modulated thickness

    International Nuclear Information System (INIS)

    Gubbiotti, G; Tacchi, S; Kostylev, M; Ivanov, E; Samarin, S; Madami, M; Carlotti, G; Ding, J; Adeyeye, A O; Zighem, F; Stashkevich, A A

    2014-01-01

    It is shown experimentally that collective Bloch spin waves are able to propagate in a dense periodic array of nanowires with step-modulated thickness along the periodicity direction. The spin wave dispersion (frequency versus wave vector k) was measured using the Brillouin light scattering technique by sweeping the wave vector perpendicularly to the wire length. Remarkably, the mode measured at the lowest frequency exhibits an oscillating dispersion and its frequency is up-shifted with respect to the homogeneous-thickness wires of the same width. The modes located at higher frequencies have negligible dependencies on the wave number, i.e. are practically dispersionless. Complementary ferromagnetic resonance measurements enabled us to independently measure the whole set of modes at k = 0, showing a good agreement with the Brillouin light scattering data. These results have been successfully reproduced in a numerical simulation employing a two-dimensional Green's function description of the dynamic dipole field of the precessing magnetization. The theory also allowed visualizing the non-trivial distribution of dynamic magnetization across the wire cross-section and estimating the Brillouin light scattering cross-section. The analysis of these intensities suggests complicated magneto-optical coupling between the light and the dynamic magnetization in the arrays of nanowires with step-modulated thickness. This work can stimulate the design, tailoring, and characterization of three-dimensional magnonic crystals. (paper)

  19. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    Science.gov (United States)

    Maroof, R.; Ali, S.; Mushtaq, A.; Qamar, A.

    2015-11-01

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  20. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maroof, R. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Qamar, A. [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan)

    2015-11-15

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  1. Spin-off produced by the fusion research and development

    International Nuclear Information System (INIS)

    Koizumi, Koichi; Konishi, T.; Tsuji, Hiroshi

    2001-03-01

    Nuclear fusion devices are constructed by the integration of many frontier technologies and fusion science based on a wide area of science such as physics, electromagnetics, thermodynamics, mechanics, electrical engineering, electronics, material engineering, heat transfer and heat flow, thermal engineering, neutronics, cryogenics, chemical engineering, control engineering, instrumentation engineering, vacuum engineering. For this, the research and development of elementary technology for fusion devices contributes to advance the technology level of each basic field. In addition, the mutual stimulus among various research fields contributes to increase the potential level of whole 'science and technology'. The spin-offs produced by the fusion technology development give much contribution not only to the general industrial technologies such as semiconductor technology, precision machining of large component, but also contribute to the progress of the accelerator technology, application technology of superconductivity, instrumentation and diagnostics, plasma application technology, heat-resistant and heavy radiation-resistant material technology, vacuum technology, and computer simulation technology. The spin-off produced by the fusion technology development expedite the development of frontier technology of other field and give much contribution to the progress of basic science on physics, space science, material science, medical science, communication, and environment. This report describes the current status of the spin-off effects of fusion research and development by focusing on the contribution of technology development for International Thermonuclear Experimental Reactor (ITER) to industrial technology. The possibilities of future application in the future are also included in this report from the view point of researchers working for nuclear fusion development. Although the nuclear fusion research has a characteristic to integrate the frontier technologies of

  2. Theory of Collective Spin-Wave Modes of Interacting Ferromagnetic Spheres

    Science.gov (United States)

    2004-09-29

    Office (Durham) through Contract No. CS0001028. R. A. thanks also Proyecto Fondecyt Grant No. 7030063. *Present address: Universidad de Chile...Departamento de Fisica FCFM, Santiago, Chile. 1 For examples of experimental studies of the collective spin wave modes of superlattices and multilayers, see M...character to those shown above. In this case, there is no simple symmetry de - composition one canmake for the collective modes, so all branches appear

  3. Competition between spin, charge, and bond waves in a Peierls-Hubbard model

    International Nuclear Information System (INIS)

    Venegas, P.A.; Henriquez, C.; Roessler, J.

    1996-01-01

    We study a one-dimensional extended Peierls-Hubbard model coupled to intracell and intercell phonons for a half-filled band. The calculations are made using the Hartree-Fock and adiabatic approximations for arbitrary temperature. In addition to static spin, charge, and bond density waves, we predict intermediate phases that lack inversion symmetry, and phase transitions that reduce symmetry on increasing temperature. copyright 1996 The American Physical Society

  4. Spin-Wave Dispersion and Sublattice Magnetization in NiCl_2

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Birgeneau, R. J.; Als-Nielsen, Jens Aage

    1975-01-01

    temperature dependence on the sublattice magnetization, gap energy and specific heat. The authors report an inelastic neutron scattering study of the spin waves both at low temperatures and, for selected q-vectors, for temperatures up to TN=52.3K. The sublattice magnetization has been measured from 1.5K to TN......-dependent dispersion relations (together with the sublattice magnetization) and the gap energy up to approximately 0.4 TN are properly predicted....

  5. Spin-wave excitations and magnetism of sputtered Fe/Au multilayers

    Indian Academy of Sciences (India)

    2LMPG, Ecole supérieure de technologie, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Morocco. 3LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Morocco. MS received 15 September 2015; accepted 15 February 2016. Abstract. The spin-wave excitations and ...

  6. Polarization dependence of the spin-density-wave excitations in single-domain chromium

    Energy Technology Data Exchange (ETDEWEB)

    Boeni, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Roessli, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France); Sternlieb, B.J. [Brookhaven (United States); Lorenzo, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Werner, S.A. [Missouri (United States)

    1997-09-01

    A polarized neutron scattering experiment has been performed with a single-Q, single domain sample of chromium in a magnetic field of 4 T. It is confirmed that the longitudinal fluctuations are enhanced for small energy transfers and that the spin wave modes with {delta}S parallel to Q and {delta}S perpendicular to Q are similar. (author) 2 figs., 1 tab., 2 refs.

  7. 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

  8. Two-magnon Raman scattering in a spin density wave antiferromagnet

    OpenAIRE

    Schoenfeld, Friedhelm; Kampf, Arno P.; Mueller-Hartmann, Erwin

    1996-01-01

    We present the results for a model calculation of resonant two-magnon Raman scattering in a spin density wave (SDW) antiferromagnet. The resonant enhancement of the two-magnon intensity is obtained from a microscopic analysis of the photon-magnon coupling vertex. By combining magnon-magnon interactions with `triple resonance` phenomena in the vertex function the resulting intensity line shape is found to closely resemble the measured two-magnon Raman signal in antiferromagnetic cuprates. Both...

  9. Magnetic studies of spin wave excitations in Fe/Mn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco); LMPG, Ecole supérieure de technologie, Université Hassan de Casablanca, Casablanca (Morocco); Moubah, R.; El Bahoui, A.; Lassri, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco)

    2017-04-15

    The structural and magnetic properties of Fe/Mn multilayers grown by thermal evaporation technique were investigated by transmission electron microscopy, vibrating sample magnetometer and spin wave theory. Transmission electron microscopy shows that the Fe and Mn layers are continuous with a significant interfacial roughness. The magnetic properties of Fe/Mn multilayers were studied for various Fe thicknesses (t{sub Fe}). The change of magnetization as a function of temperature is well depicted by a T{sup 3/2} law. The Fe spin-wave constant was extracted and found to be larger than that reported for bulk Fe, which we attribute to the fluctuation of magnetic moments at the interface, due to the interfacial roughness. The experimental M (T) data were satisfactory fitted for multilayers with different Fe thicknesses; and several exchange interactions were extracted. - Highlights: • The structural and magnetic properties of Fe/Mn multilayers were studied. • Fe and Mn layers are continuous with an important interfacial roughness. • The Fe spin-wave constant is larger than that reported for bulk Fe due to the fluctuation of the interfacial magnetic moments.

  10. Magnetic studies of spin wave excitations in Fe/Mn multilayers

    International Nuclear Information System (INIS)

    Salhi, H.; Moubah, R.; El Bahoui, A.; Lassri, H.

    2017-01-01

    The structural and magnetic properties of Fe/Mn multilayers grown by thermal evaporation technique were investigated by transmission electron microscopy, vibrating sample magnetometer and spin wave theory. Transmission electron microscopy shows that the Fe and Mn layers are continuous with a significant interfacial roughness. The magnetic properties of Fe/Mn multilayers were studied for various Fe thicknesses (t Fe ). The change of magnetization as a function of temperature is well depicted by a T 3/2 law. The Fe spin-wave constant was extracted and found to be larger than that reported for bulk Fe, which we attribute to the fluctuation of magnetic moments at the interface, due to the interfacial roughness. The experimental M (T) data were satisfactory fitted for multilayers with different Fe thicknesses; and several exchange interactions were extracted. - Highlights: • The structural and magnetic properties of Fe/Mn multilayers were studied. • Fe and Mn layers are continuous with an important interfacial roughness. • The Fe spin-wave constant is larger than that reported for bulk Fe due to the fluctuation of the interfacial magnetic moments.

  11. Angle-dependent spin-wave resonance spectroscopy of (Ga,Mn)As films

    Science.gov (United States)

    Dreher, L.; Bihler, C.; Peiner, E.; Waag, A.; Schoch, W.; Limmer, W.; Goennenwein, S. T. B.; Brandt, M. S.

    2013-06-01

    A modeling approach for standing spin-wave resonances based on a finite-difference formulation of the Landau-Lifshitz-Gilbert equation is presented. In contrast to a previous study [C. Bihler , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.79.045205 79, 045205 (2009)], this formalism accounts for elliptical magnetization precession and magnetic properties arbitrarily varying across the layer thickness, including the magnetic anisotropy parameters, the exchange stiffness, the Gilbert damping, and the saturation magnetization. To demonstrate the usefulness of our modeling approach, we experimentally study a set of (Ga,Mn)As samples grown by low-temperature molecular-beam epitaxy by means of angle-dependent standing spin-wave resonance spectroscopy and electrochemical capacitance-voltage measurements. By applying our modeling approach, the angle dependence of the spin-wave resonance data can be reproduced in a simulation with one set of simulation parameters for all external field orientations. We find that the approximately linear gradient in the out-of-plane magnetic anisotropy is related to a linear gradient in the hole concentrations of the samples.

  12. Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Rousseau, Olivier [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Otani, YoshiChika [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2014-10-28

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  13. Spin wave propagation detected over 100 μm in half-metallic Heusler alloy Co2MnSi

    Science.gov (United States)

    Stückler, Tobias; Liu, Chuanpu; Yu, Haiming; Heimbach, Florian; Chen, Jilei; Hu, Junfeng; Tu, Sa; Alam, Md. Shah; Zhang, Jianyu; Zhang, Youguang; Farrell, Ian L.; Emeny, Chrissy; Granville, Simon; Liao, Zhi-Min; Yu, Dapeng; Zhao, Weisheng

    2018-03-01

    The field of magnon spintronics offers a charge current free way of information transportation by using spin waves (SWs). Compared to forward volume spin waves for example, Damon-Eshbach (DE) SWs need a relatively weak external magnetic field which is suitable for small spintronic devices. In this work we study DE SWs in Co2MnSi, a half-metallic Heusler alloy with significant potential for magnonics. Thin films have been produced by pulsed laser deposition. Integrated coplanar waveguide (CPW) antennas with different distances between emitter and detection antenna have been prepared on a Co2MnSi film. We used a vector network analyzer to measure spin wave reflection and transmission. We observe spin wave propagation up to 100 μm, a new record for half-metallic Heusler thin films.

  14. Influence of external magnetic field on parameters of surface two-focus spin-wave ferromagnetic lens

    International Nuclear Information System (INIS)

    Reshetnyak, S.A.; Berezhinskij, A.S.

    2012-01-01

    The influence of external magnetic field on refraction of surface spin wave propagating through inhomogeneity created in the form of a lens, that is a biaxial ferromagnet placed into uniaxial ferromagnetic medium, is studied.

  15. Edge-state-dependent tunneling of dipole-exchange spin waves in submicrometer magnetic strips with an air gap.

    Science.gov (United States)

    Xing, X J; Zhang, D; Li, S W

    2012-12-14

    We have investigated the tunneling of dipole-exchange spin waves across an air gap in submicrometer-sized permalloy magnetic strips by means of micromagnetic simulations. The magnetizations beside the gap could form three distinct end-domain states with various strengths of dipolar coupling. Spin-wave tunneling through the gap at individual end-domain states is studied. It is found that the tunneling behavior is strongly dependent on these domain states. Nonmonotonic decay of transmission of spin waves with the increase of the gap width is observed. The underlying mechanism for these behaviors is proposed. The tunneling characteristics of the dipole-exchange spin waves differ essentially from those of the magnetostatic ones reported previously.

  16. Phase control of spin waves based on a magnetic defect in a one-dimensional magnonic crystal

    Science.gov (United States)

    Baumgaertl, Korbinian; Watanabe, Sho; Grundler, Dirk

    2018-04-01

    Magnonic crystals are interesting for spin-wave based data processing. We investigate one-dimensional magnonic crystals (1D MCs) consisting of bistable Co 20 Fe 60 B 20 nanostripes separated by 75 nm wide air gaps. By adjusting the magnetic history, we program a single stripe of opposed magnetization in an otherwise saturated 1D MC. Its influence on propagating spin waves is studied via broadband microwave spectroscopy. Depending on an in-plane bias magnetic field, we observe spin wave phase shifts of up to almost π and field-controlled attenuation attributed to the reversed nanostripe. Our findings are of importance for magnetologics, where the control of spin wave phases is essential.

  17. Physics Colloquium: Theory of the spin wave Seebeck effect in magnetic insulators

    CERN Multimedia

    Université de Genève

    2011-01-01

    Geneva University Physics Department 24, quai Ernest-Ansermet CH-1211 Geneva 4 Lundi 28 février 2011 17h00 - École de Physique, Auditoire Stückelberg Theory of the spin wave Seebeck effect in magnetic insulators Prof. Gerrit Bauer Delft University of Technology The subfield of spin caloritronics addresses the coupling of heat, charge and spin currents in nanostructures. In the center of interest is here the spin Seebeck effect, which was discovered in an iron-nickel alloy. Uchida et al. recently observed the effect also in an electrically insulating Yttrium Iron Garnett (YIG) thin magnetic film. To our knowledge this is the first observation of a Seebeck effect generated by an insulator, implying that the physics is fundamentally different from the conventional Seebeck effect in metals. We explain the experiments by the pumping of a spin current into the detecting contacts by the thermally excited magnetization dynamics. In this talk I will give a brief overview over the state o...

  18. Spin-wave thermal population as temperature probe in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Le Goff, A., E-mail: adrien.le-goff@u-psud.fr; Devolder, T. [Institut d' Electronique Fondamentale, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Nikitin, V. [SAMSUNG Electronics Corporation, 601 McCarthy Blvd Milpitas, California 95035 (United States)

    2016-07-14

    We study whether a direct measurement of the absolute temperature of a Magnetic Tunnel Junction (MTJ) can be performed using the high frequency electrical noise that it delivers under a finite voltage bias. Our method includes quasi-static hysteresis loop measurements of the MTJ, together with the field-dependence of its spin wave noise spectra. We rely on an analytical modeling of the spectra by assuming independent fluctuations of the different sub-systems of the tunnel junction that are described as macrospin fluctuators. We illustrate our method on perpendicularly magnetized MgO-based MTJs patterned in 50 × 100 nm{sup 2} nanopillars. We apply hard axis (in-plane) fields to let the magnetic thermal fluctuations yield finite conductance fluctuations of the MTJ. Instead of the free layer fluctuations that are observed to be affected by both spin-torque and temperature, we use the magnetization fluctuations of the sole reference layers. Their much stronger anisotropy and their much heavier damping render them essentially immune to spin-torque. We illustrate our method by determining current-induced heating of the perpendicularly magnetized tunnel junction at voltages similar to those used in spin-torque memory applications. The absolute temperature can be deduced with a precision of ±60 K, and we can exclude any substantial heating at the spin-torque switching voltage.

  19. Magnetic properties of the spin-density wave in (TMTSF)2X and (TMTTF)2Br

    International Nuclear Information System (INIS)

    Matsunaga, N.; Hosokawa, Y.; Iwasaki, H.; Nomura, K.; Nakamura, T.; Takahashi, T.; Saito, G.

    1999-01-01

    Magnetic properties of the spin density wave (SDW) phase in (TMTSF) 2 X (X=AsF 6 , PF 6 ) and (TMTTF) 2 Br were investigated through analyses of 1 H-NMR and static magnetization measurements. A divergent peak was observed, at the temperature T * well below the SDW transition temperature, in the 1 H spin-lattice relaxation rate in the incommensurate SDW phase of (TMTSF) 2 X. A decrease of the differential magnetic susceptibility of (TMTSF) 2 X with the field parallel to the a-axis was observed around T * . This anomaly indicates a difference of the spin canting above and below T * which divides the SDW phase. In the measurements of magnetic susceptibility on the commensurate SDW phase of (TMTTF) 2 Br, a large decrease of the spin susceptibility was observed above T SDW and non-activated type behavior in the b'-axis susceptibility is observed below the spin-flop field at low temperature. The data are discussed on the basis of commensurability. (orig.)

  20. Spin-wave dynamics in Invar Fe65Ni35 studied by small-angle polarized neutron scattering

    NARCIS (Netherlands)

    Brück, E.H.; Grigoriev, S.V.; Deriglazov, V.V.; Okorokov, A.I.; Dijk van, N.H.; Klaasse, J.C.P.

    2002-01-01

    Abstract. Spin dynamics in Fe65Ni35 Invar alloy has been studied by left-right asymmetry of small-angle polarized neutron scattering below TC=485 K in external magnetic fields of H=0.05-0.25 T inclined relative to the incident beam. The spin-wave stiffness D and the damping & were obtained by

  1. Spin wave mode coexistence on the nanoscale: A consequence of the Oersted field induced asymmetric energy landscape

    Science.gov (United States)

    Dumas, Randy

    2014-03-01

    The emerging field of magnonics relies on the systematic generation, manipulation, and detection of spin waves (SWs). Nanocontact spin torque oscillators (NC-STOs) provide an ideal platform to study spin transfer torque induced SW emission. In analogy to two species competing for the same food supply it has been argued that only one SW mode can survive in the steady state. However, as evidenced in many experiments clear signatures of mode-hopping are often observed. Here, we present a third possibility, namely that under the correct experimental conditions, mode coexistencecan be realized in NC-STOs. Micromagnetic simulations reveal that the SW modes are spatially separated under the NC. Mode coexistence is facilitated by the local field asymmetries induced by the spatially inhomogeneous Oersted field in the vicinity of the NC and further promoted by SW localization. Finally, both simulation and experiment reveal a weak low frequency signal exactly at the difference of the mode frequencies, consistent with inter-modulation of two coexistent modes. The Swedish Research Council, The Swedish Foundation for Strategic Research, and the Knut and Alice Wallenberg Foundation are acknowledged. ANL is a US DOE Science Laboratory operated under contract no. DE-AC02-06CH11357 by UChicago Argonne, LLC.

  2. Wave aberrations in a spinning pipe gas lens

    CSIR Research Space (South Africa)

    Mafusire, C

    2009-06-01

    Full Text Available The graded index (GRIN-like) medium generated by a gas inside a heated pipe when it is rotated about its longitudinal axis has the ability to focus a laser beam. However, recent research has shown that the medium generated has a deleterious effect...

  3. Exchange interactions, spin waves, and transition temperatures in itinerant magnets

    Czech Academy of Sciences Publication Activity Database

    Turek, Ilja; Kudrnovský, Josef; Drchal, Václav; Bruno, P.

    2003-01-01

    Roč. 1, č. 59 (2003), s. 112-147 R&D Projects: GA ČR GA106/02/0943; GA AV ČR IAA1010203 Institutional research plan: CEZ:AV0Z2041904 Keywords : exchange interactions * itinerant magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism http://psi-k.dl.ac.uk/psi-k/newsletters.html

  4. Banks of templates for directed searches of gravitational waves from spinning neutron stars

    International Nuclear Information System (INIS)

    Pisarski, Andrzej; Jaranowski, Piotr; Pietka, Maciej

    2011-01-01

    We construct efficient banks of templates suitable for directed searches of almost monochromatic gravitational waves originating from spinning neutron stars in our Galaxy in data being collected by currently operating interferometric detectors. We thus assume that the position of the gravitational-wave source in the sky is known, but we do not assume that the wave's frequency and its derivatives are a priori known. In the construction we employ a simplified model of the signal with constant amplitude and phase which is a polynomial function of time. All our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood F-statistic for nodes of the grids defining the bank. We study and employ the dependence of the grid's construction on the choice of the position of the observational interval with respect to the origin of time axis. We also study the usage of the fast Fourier transform algorithms with nonstandard frequency resolutions achieved by zero padding or folding the data. In the case of the gravitational-wave signal with one spin-down parameter included we have found grids with covering thicknesses which are only 0.1-16% larger than the thickness of the optimal 2-dimensional hexagonal covering.

  5. Self-consistent treatment of interacting spin waves at finite temperatures; Etude a temperature finie d'un systeme d'ondes de spin en interaction dans une approximation self-consistante

    Energy Technology Data Exchange (ETDEWEB)

    Bloch, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    A spin wave theory is developed where account is taken of spin wave interactions at finite temperatures. The temperature dependence of the spin wave energies and of the magnetization is derived. The theory is developed for ferro-, ferri-, and antiferromagnets. (author) [French] On expose une theorie d'ondes de spin en interaction a temperature finie. On en deduit l'evolution avec la temperature du spectre en energie des ondes de spin et de l'aimantation. La theorie est developpee pour les corps ferro-, ferri-, et antiferromagnetiques. (auteur)

  6. Excitation of spin waves in BiFeO3 multiferroic film by the slot line transducer

    Science.gov (United States)

    Korneev, V. I.; Popkov, A. F.; Solov'yov, S. V.

    2018-01-01

    Analysis of the efficiency of magnetoelectric excitation of spin-waves in BiFeO3 multiferroic films by a slot line is performed based on the solution of dynamic Ginzburg-Landau equations for the antiferromagnetic vector. The excitation efficiency is determined by the magnitude of the conversion coefficient of the electromagnetic wave to the spin wave by the slot line transducer or in other words, losses on conversion in the slot line. Calculations are made for a homogeneous antiferromagnetic state of the multiferroic in the presence of a sufficiently large magnetic field and for a spatially modulated spin state (SMSS) at zero magnetic field. It is shown that in the case of a homogeneous antiferromagnetic state, the losses on the excitation of spin waves exceed the excitation efficiency in the SMSS state; however, as the frequency approaches the spin excitation gap, it falls and becomes lower than in the SMSS state. Spin wave excitation in the presence of antiferromagnetic cycloid strongly depends on the relation of the slot width of the transducer to the cycloid periodicity and on the magnitude of the shift of the position of the transducer along the cycloid on its period. The usage of multiferroics for delay lines in the considered frequency range from 100 to 600 GHz requires significant reduction in conversion and propagation losses. More promising seems multiferroic usage in phase shifters and switches for this range.

  7. Parallel ferromagnetic resonance and spin-wave excitation in exchange-biased NiFe/IrMn bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Marcos Antonio de, E-mail: marcossharp@gmail.com [Instituto de Física, Universidade Federal de Goiás, Goiânia, 74001-970 (Brazil); Pelegrini, Fernando [Instituto de Física, Universidade Federal de Goiás, Goiânia, 74001-970 (Brazil); Alayo, Willian [Departamento de Física, Universidade Federal de Pelotas, Pelotas, 96010-900 (Brazil); Quispe-Marcatoma, Justiniano; Baggio-Saitovitch, Elisa [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, 22290-180 (Brazil)

    2014-10-01

    Ferromagnetic Resonance study of sputtered Ru(7 nm)/NiFe(t{sub FM})/IrMn(6 nm)/Ru(5 nm) exchange-biased bilayers at X and Q-band microwave frequencies reveals the excitation of spin-wave and NiFe resonance modes. Angular variations of the in-plane resonance fields of spin-wave and NiFe resonance modes show the effect of the unidirectional anisotropy, which is about twice larger for the spin-wave mode due to spin pinning at the NiFe/IrMn interface. At Q-band frequency the angular variations of in-plane resonance fields also reveal the symmetry of a uniaxial anisotropy. A modified theoretical model which also includes the contribution of a rotatable anisotropy provides a good description of the experimental results.

  8. Detecting gravitational waves from precessing binaries of spinning compact objects: Adiabatic limit

    International Nuclear Information System (INIS)

    Buonanno, Alessandra; Chen Yanbei; Vallisneri, Michele

    2003-01-01

    Black-hole (BH) binaries with single-BH masses m=(5-20)M · , moving on quasicircular orbits, are among the most promising sources for first-generation ground-based gravitational-wave (GW) detectors. Until now, the development of data-analysis techniques to detect GWs from these sources has been focused mostly on nonspinning BHs. The data-analysis problem for the spinning case is complicated by the necessity to model the precession-induced modulations of the GW signal, and by the large number of parameters needed to characterize the system, including the initial directions of the spins, and the position and orientation of the binary with respect to the GW detector. In this paper we consider binaries of maximally spinning BHs, and we work in the adiabatic-inspiral regime to build families of modulated detection templates that (i) are functions of very few physical and phenomenological parameters, (ii) model remarkably well the dynamical and precessional effects on the GW signal, with fitting factors on average > or approx. 0.97, (iii) but, however, might require increasing the detection thresholds, offsetting at least partially the gains in the fitting factors. Our detection-template families are quite promising also for the case of neutron-star-black-hole binaries, with fitting factors on average ≅0.93. For these binaries we also suggest (but do not test) a further template family, which would produce essentially exact waveforms written directly in terms of the physical spin parameters

  9. Dirac-fermions in graphene d-wave superconducting heterojunction with the spin orbit interaction

    Science.gov (United States)

    Wang, Juntao; Wang, Andong; Zhang, Rui; Sun, Deng; Yang, Yanling

    2017-09-01

    In this study, based on the Dirac-Bogoliubov-de Gennes equation, we theoretically investigate the interaction effect between the anisotropic d-wave pairing symmetry and the spin orbit interaction (the Rashba spin orbit interaction (RSOI) and the Dresselhaus spin orbit interaction (DSOI)) in a graphene superconducting heterojunction. We find that the spin orbit interaction (SOI) plays a critical role on the tunneling conductance in the pristine case, but minimally affecting the tunneling conductance in the heavily doped case. As for the zero bias state, in contrast to the keep intact feature in the heavily doped case, it exhibits a distinct dependence on the RSOI and the DSOI in the pristine case. In particular, the damage of the zero bias state with a slight DSOI results in the disappearance of the zero bias conductance peak. Moreover, the tunneling conductances also show a qualitative difference with respect to the RSOI when both the RSOI and the DSOI are finite. These remarkable results suggest that the SOI and the anisotropic superconducting gap can be regarded as a key tool for diagnosing the specular Andreev reflection.

  10. Spin-Wave Excitations Evidencing the Kitaev Interaction in Single Crystalline α -RuCl3

    Science.gov (United States)

    Ran, Kejing; Wang, Jinghui; Wang, Wei; Dong, Zhao-Yang; Ren, Xiao; Bao, Song; Li, Shichao; Ma, Zhen; Gan, Yuan; Zhang, Youtian; Park, J. T.; Deng, Guochu; Danilkin, S.; Yu, Shun-Li; Li, Jian-Xin; Wen, Jinsheng

    2017-03-01

    Kitaev interactions underlying a quantum spin liquid have long been sought, but experimental data from which their strengths can be determined directly, are still lacking. Here, by carrying out inelastic neutron scattering measurements on high-quality single crystals of α -RuCl3 , we observe spin-wave spectra with a gap of ˜2 meV around the M point of the two-dimensional Brillouin zone. We derive an effective-spin model in the strong-coupling limit based on energy bands obtained from first-principles calculations, and find that the anisotropic Kitaev interaction K term and the isotropic antiferromagnetic off-diagonal exchange interaction Γ term are significantly larger than the Heisenberg exchange coupling J term. Our experimental data can be well fit using an effective-spin model with K =-6.8 meV and Γ =9.5 meV . These results demonstrate explicitly that Kitaev physics is realized in real materials.

  11. Magnetic structures, phase diagram and spin waves of magneto-electric LiNiPO4

    DEFF Research Database (Denmark)

    Jensen, Thomas Bagger Stibius

    2007-01-01

    LiNiPO4 is a magneto-electric material, having co-existing antiferromagnetic and ferroelectric phases when suitable magnetic fields are applied at low temperatures. Such systems have received growing interest in recent years, but the nature of the magneticelectric couplings is yet to be fully...... through the last three years, it is not the primary subject of this thesis. The objective of the phD project has been to provide groundwork that may be beneficiary to future studies of LiNiPO4. More specifically, we have mapped out the magnetic HT phase diagram with magnetic fields below 14.7 T applied...... along the crystallographic c-axis, determined the magnetic structures for the phases in the phase diagram, and have set up a spin model Hamiltonian describing the spin wave dynamics and estimating the relevant magnetic interactions....

  12. Basic mode of nonlinear spin-wave resonance in normally magnetized ferrite films

    International Nuclear Information System (INIS)

    Gulyaev, Yu.V.; Zil'berman, P.E.; Timiryazev, A.G.; Tikhomirova, M.P.

    2000-01-01

    Modes of nonlinear and spin-wave resonance (SWR) in the normally magnetized ferrite films were studied both theoretically and experimentally. The particular emphasis was placed on the basic mode of SWR. One showed theoretically that with the growth of the precession amplitude the profile of the basic mode changed. The nonlinear shift of the resonance field depends on the parameters of fixing of the surface spins. Films of ferroyttrium garnet (FYG) with strong gradient of the single-axis anisotropy field along the film thickness, as well as, FYG films of the submicron thickness where investigated experimentally. With the intensification of Uhf-power one observed the sublinear shift of the basic mode resonance field following by the superlinear growth of the absorbed power. That kind of behaviour is explained by variation of the profile of the varying magnetization space distribution [ru

  13. Research on backward traveling wave electron linac

    International Nuclear Information System (INIS)

    Chen Huaibi; Zheng Shuxin; Ding Xiaodong; Lin Yuzheng

    1999-01-01

    Future electron linacs require high gradient acceleration. The studies on the high shunt impedance backward traveling wave electron linac accelerating structure (BTW) are presented. At first, the characteristics of BTW are researched. The option of mode and optimal design methods of accelerating cavity for BTW are studied. A physical design method for BTW accelerators, including longitudinal and transversal particle dynamics, is given. Based on above studies, a 9 MeV BTW accelerating tube at 3π/4 mode with frequency 2856 MHz for inspecting large container as radiation source at customs is designed, and a comparison with disk-loaded waveguide accelerating tube is made. The result of research leads to the conclusion that backward traveling wave accelerating structure is preferable. Because BTW has higher effective shunt impedance, shorter filling time and more stable operation

  14. Voltage-Controlled Reconfigurable Spin-Wave Nanochannels and Logic Devices

    Science.gov (United States)

    Rana, Bivas; Otani, YoshiChika

    2018-01-01

    Propagating spin waves (SWs) promise to be a potential information carrier in future spintronics devices with lower power consumption. Here, we propose reconfigurable nanochannels (NCs) generated by voltage-controlled magnetic anisotropy (VCMA) in an ultrathin ferromagnetic waveguide for SW propagation. Numerical micromagnetic simulations are performed to demonstrate the confinement of magnetostatic forward volumelike spin waves in NCs by VCMA. We demonstrate that the NCs, with a width down to a few tens of a nanometer, can be configured either into a straight or curved structure on an extended SW waveguide. The key advantage is that either a single NC or any combination of a number of NCs can be easily configured by VCMA for simultaneous propagation of SWs either with the same or different wave vectors according to our needs. Furthermore, we demonstrate the logic operation of a voltage-controlled magnonic xnor and universal nand gate and propose a voltage-controlled reconfigurable SW switch for the development of a multiplexer and demultiplexer. We find that the NCs and logic devices can even be functioning in the absence of the external-bias magnetic field. These results are a step towards the development of all-voltage-controlled magnonic devices with an ultralow power consumption.

  15. Quantum Monte Carlo studies of a metallic spin-density wave transition

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, Max Henner

    2017-01-20

    Plenty experimental evidence indicates that quantum critical phenomena give rise to much of the rich physics observed in strongly correlated itinerant electron systems such as the high temperature superconductors. A quantum critical point of particular interest is found at the zero-temperature onset of spin-density wave order in two-dimensional metals. The appropriate low-energy theory poses an exceptionally hard problem to analytic theory, therefore the unbiased and controlled numerical approach pursued in this thesis provides important contributions on the road to comprehensive understanding. After discussing the phenomenology of quantum criticality, a sign-problem-free determinantal quantum Monte Carlo approach is introduced and an extensive toolbox of numerical methods is described in a self-contained way. By the means of large-scale computer simulations we have solved a lattice realization of the universal effective theory of interest. The finite-temperature phase diagram, showing both a quasi-long-range spin-density wave ordered phase and a d-wave superconducting dome, is discussed in its entirety. Close to the quantum phase transition we find evidence for unusual scaling of the order parameter correlations and for non-Fermi liquid behavior at isolated hot spots on the Fermi surface.

  16. Introduction to Shock Waves and Shock Wave Research

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, William Wyatt [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    M-9 and a number of other organizations at LANL and elsewhere study materials in dynamic processes. Often, this is described as “shock wave research,” but in reality is broader than is implied by that term. Most of our work is focused on dynamic compression and associated phenomena, but you will find a wide variety of things we do that, while related, are not simple compression of materials, but involve a much richer variety of phenomena. This tutorial will introduce some of the underlying physics involved in this work, some of the more common types of phenomena we study, and common techniques. However, the list will not be exhaustive by any means.

  17. Spin wave energy dispersion in KCuF/sub 3/: a nearly one-dimensional spin-1/2 antiferromagnet. [4. 7/sup 0/K

    Energy Technology Data Exchange (ETDEWEB)

    Hutchings, M T; Ikeda, H; Milne, J M

    1979-09-28

    Using inelastic neutron scattering techniques, the spin wave energy dispersion in the (010) plane of the distorted perovskite KCuF/sub 3/, which exhibits many magnetic properties of the spin-1/2 one-dimensional antiferromagnet, has been investigated at 4.7 K (T/sub N/ = 39 K). The measurements confirm the very strong exchange interaction between the spins in the (001) direction, and show that in this direction the expression for the excitation energies of the spin-1/2 antiferromagnetic chain given by J des Cloizeaux and J J Pearson is obeyed. The exchange interaction between these chains is found to be only 1.6% of that within the chains.

  18. Spin-wave excitation and Moessbauer spectrometry of amorphous interface in Tb/Fe multilayer

    International Nuclear Information System (INIS)

    El Khiraoui, S.; Sajieddine, M.; Lassri, H.; Sahlaoui, M.

    2009-01-01

    Magnetic properties of Tb(48 A)/Fe(26 A) multilayer were studied with Moessbauer spectrometry at different temperatures before and after isothermal annealing at 673 K. For this last case, a significant perpendicular magnetic anisotropy is induced. This phenomenon is related to the existence of an amorphous and homogenous Tb-Fe alloy, located at the interfaces, which is produced by interdiffusion during the heat processing. The thermal evolution of hyperfine field deduced for interfacial Tb-Fe alloy is found to obey the Bloch law. The spin-wave stiffness constant, the distance between nearest magnetic atoms and the exchange parameter A were calculated from the experimental results

  19. Localized excitation of magnetostatic surface spin waves in yttrium iron garnet by shorted coaxial probe detected via spin pumping and rectification effect

    International Nuclear Information System (INIS)

    Soh, Wee Tee; Ong, C. K.; Peng, Bin

    2015-01-01

    We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films

  20. Brillouin light scattering study of spin waves in NiFe/Co exchange spring bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Haldar, Arabinda; Banerjee, Chandrima; Laha, Pinaki; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098 (India)

    2014-04-07

    Spin waves are investigated in Permalloy(Ni{sub 80}Fe{sub 20})/Cobalt(Co) exchange spring bilayer thin films using Brillouin light scattering (BLS) experiment. The magnetic hysteresis loops measured by magneto-optical Kerr effect show a monotonic decrease in coercivity of the bilayer films with increasing Py thickness. BLS study shows two distinct modes, which are modelled as Damon-Eshbach and perpendicular standing wave modes. Linewidths of the frequency peaks are found to increase significantly with decreasing Py layer thickness. Interfacial roughness causes to fluctuate exchange coupling at the nanoscale regimes and the effect is stronger for thinner Py films. A quantitative analysis of the magnon linewidths shows the presence of strong local exchange coupling field which is much larger compared to macroscopic exchange field.

  1. Frequency-domain reduced order models for gravitational waves from aligned-spin compact binaries

    International Nuclear Information System (INIS)

    Pürrer, Michael

    2014-01-01

    Black-hole binary coalescences are one of the most promising sources for the first detection of gravitational waves. Fast and accurate theoretical models of the gravitational radiation emitted from these coalescences are highly important for the detection and extraction of physical parameters. Spinning effective-one-body models for binaries with aligned-spins have been shown to be highly faithful, but are slow to generate and thus have not yet been used for parameter estimation (PE) studies. I provide a frequency-domain singular value decomposition-based surrogate reduced order model that is thousands of times faster for typical system masses and has a faithfulness mismatch of better than ∼0.1% with the original SEOBNRv1 model for advanced LIGO detectors. This model enables PE studies up to signal-to-noise ratios (SNRs) of 20 and even up to 50 for total masses below 50 M ⊙ . This paper discusses various choices for approximations and interpolation over the parameter space that can be made for reduced order models of spinning compact binaries, provides a detailed discussion of errors arising in the construction and assesses the fidelity of such models. (paper)

  2. Effect of spin-orbit coupling on the wave vector and spin dependent transmission probability for the GaN/AlGaN/GaN heterostructure

    International Nuclear Information System (INIS)

    Li, M; Zhao, Z B; Fan, L B

    2015-01-01

    The effect of the Rashba and Dresselhaus spin–orbit coupling (SOC) on the transmission of electrons through the GaN/AlGaN/GaN heterostructure is studied. It is found that the Dresselhaus SOC causes the evident dependence of the transmission probability on the spin polarization and the in-plane wave vector of electrons, and also induces evident spin splitting of the resonant peaks in the (E z -k) plane. Because the magnitude of the Rashba SOC is relatively small, its effect on the transmission of electrons is much less. As k increases, the peaks of transmission probability for spin-up electrons (T + ) shift to a higher energy region and increase in magnitude, while the peaks of transmission probability for spin-down electrons (T − ) shift to a lower energy region and decrease in magnitude. The polarization efficiency (P) is found to peak at the resonant energies and increases with the in-plane wave vector. Moreover, the built-in electric field caused by the spontaneous and piezoelectric polarization can increase the amplitude of P. Results obtained here are helpful for the efficient spin injection into the III-nitride heterostructures by nonmagnetic means from the device point of view. (paper)

  3. Frequency and magnetic field mapping of magnetoelastic spin pumping in high overtone bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2018-05-01

    Full Text Available We report on the first observation of microvolt-scale inverse spin Hall effect (ISHE dc voltage driven by an acoustic spin pumping (ASP in a bulk acoustic wave (BAW resonator formed by a Al-ZnO-Al-YIG(1-GGG-YIG(2-Pt structure. When 2 mW power is applied to an Al-ZnO-Al transducer, the voltage VISHE ∼ 4 μV in the Pt film is observed as a result of resonant ASP from YIG(2 to Pt in the area ∼ 170 μm. The results of frequency and magnetic field mapping of VISHE(f,H together with reflectivity of the resonator show an obvious agreement between the positions of the voltage maxima and BAW resonance frequencies fn(H on the (f, H plane. At the same time a significant asymmetry of the VISHE(fn(H value in reference to the magnetoelastic resonance (MER line fMER(H position is revealed, which is explained by asymmetry of the magnetoelastic waves dispersion law.

  4. Frequency and magnetic field mapping of magnetoelastic spin pumping in high overtone bulk acoustic wave resonator

    Science.gov (United States)

    Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Luzanov, V. A.; Raevskiy, A. O.; Kotov, V. A.

    2018-05-01

    We report on the first observation of microvolt-scale inverse spin Hall effect (ISHE) dc voltage driven by an acoustic spin pumping (ASP) in a bulk acoustic wave (BAW) resonator formed by a Al-ZnO-Al-YIG(1)-GGG-YIG(2)-Pt structure. When 2 mW power is applied to an Al-ZnO-Al transducer, the voltage VISHE ˜ 4 μV in the Pt film is observed as a result of resonant ASP from YIG(2) to Pt in the area ˜ 170 μm. The results of frequency and magnetic field mapping of VISHE(f,H) together with reflectivity of the resonator show an obvious agreement between the positions of the voltage maxima and BAW resonance frequencies fn(H) on the (f, H) plane. At the same time a significant asymmetry of the VISHE(fn(H)) value in reference to the magnetoelastic resonance (MER) line fMER(H) position is revealed, which is explained by asymmetry of the magnetoelastic waves dispersion law.

  5. Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

    Directory of Open Access Journals (Sweden)

    V. L. Zhang

    2016-11-01

    Full Text Available The spin-wave dispersions in nanostructured magnonic crystals with periodic defects have been mapped by Brillouin light scattering. The otherwise perfect crystals are one-dimensional arrays of alternating 460nm-wide Ni80Fe20 stripes and 40nm-wide air gaps, where one in ten Ni80Fe20 stripes is a defect of width other than 460 nm. Experimentally, the defects are manifested as additional Brillouin peaks, lying within the first and second bandgaps of the perfect crystal, whose frequencies decrease with increasing defect stripe width. Finite-element calculations, based on a supercell comprising one defect and nine perfect Py stripes, show that the defect modes are localized about the defects, with the localization exhibiting an approximate U-shaped dependence on defect size. Calculations also reveal extra magnon branches and the opening of mini-bandgaps, within the allowed bands of the perfect crystal, arising from Bragg reflections at the boundaries of the shorter supercell Brillouin zone. Simulated magnetization profiles of the band-edge modes of the major and mini-bandgaps reveal their different symmetries and localization properties. The findings could find application in microwave magnonic devices like single-frequency passband spin-wave filters.

  6. 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.

  7. Spin-wave resonance frequency in ferromagnetic thin film with interlayer exchange coupling and surface anisotropy

    Science.gov (United States)

    Zhang, Shuhui; Rong, Jianhong; Wang, Huan; Wang, Dong; Zhang, Lei

    2018-01-01

    We have investigated the dependence of spin-wave resonance(SWR) frequency on the surface anisotropy, the interlayer exchange coupling, the ferromagnetic layer thickness, the mode number and the external magnetic field in a ferromagnetic superlattice film by means of the linear spin-wave approximation and Green's function technique. The SWR frequency of the ferromagnetic thin film is shifted to higher values corresponding to those of above factors, respectively. It is found that the linear behavior of SWR frequency curves of all modes in the system is observed as the external magnetic field is increasing, however, SWR frequency curves are nonlinear with the lower and the higher modes for different surface anisotropy and interlayer exchange coupling in the system. In addition, the SWR frequency of the lowest (highest) mode is shifted to higher (lower) values when the film thickness is thinner. The interlayer exchange coupling is more important for the energetically higher modes than for the energetically lower modes. The surface anisotropy has a little effect on the SWR frequency of the highest mode, when the surface anisotropy field is further increased.

  8. Tweaking the spin-wave dispersion and suppressing the incommensurate phase in LiNiPO4 by iron substitution

    DEFF Research Database (Denmark)

    Li, Jiying; Jensen, Thomas Bagger Stibius; Andersen, Niels Hessel

    2009-01-01

    ) indicates the instability of the Ising-type ground state that eventually evolves into the incommensurate phase as the temperature is raised. The pure LiNiPO4 system (x=0) undergoes a first-order magnetic phase transition from a long-range incommensurate phase to an antiferromagnetic (AFM) ground state at TN......Elastic and inelastic neutron-scattering studies of Li(Ni1−xFex)PO4 single crystals reveal anomalous spin-wave dispersions along the crystallographic direction parallel to the characteristic wave vector of the magnetic incommensurate phase. The anomalous spin-wave dispersion (magnetic soft mode......=20.8 K. At 20% Fe concentrations, although the AFM ground state is to a large extent preserved as that of the pure system, the phase transition is second order, and the incommensurate phase is completely suppressed. Analysis of the dispersion curves using a Heisenberg spin Hamiltonian that includes...

  9. Low-relaxation spin waves in laser-molecular-beam epitaxy grown nanosized yttrium iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Lutsev, L. V., E-mail: l-lutsev@mail.ru; Korovin, A. M.; Bursian, V. E.; Gastev, S. V.; Fedorov, V. V.; Suturin, S. M.; Sokolov, N. S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2016-05-02

    Synthesis of nanosized yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10{sup −5}. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

  10. Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

    Science.gov (United States)

    Maendl, Stefan; Grundler, Dirk

    2018-05-01

    We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

  11. Wave Energy Research, Testing and Demonstration Center

    Energy Technology Data Exchange (ETDEWEB)

    Batten, Belinda [Oregon State Univ., Corvallis, OR (United States)

    2014-09-30

    The purpose of this project was to build upon the research, development and testing experience of the Northwest National Marine Renewable Energy Center (NNMREC) to establish a non-grid connected open-ocean testing facility for wave energy converters (WECs) off the coast of Newport, Oregon. The test facility would serve as the first facility of its kind in the continental US with a fully energetic wave resource where WEC technologies could be proven for west coast US markets. The test facility would provide the opportunity for self-contained WEC testing or WEC testing connected via an umbilical cable to a mobile ocean test berth (MOTB). The MOTB would act as a “grid surrogate” measuring energy produced by the WEC and the environmental conditions under which the energy was produced. In order to realize this vision, the ocean site would need to be identified through outreach to community stakeholders, and then regulatory and permitting processes would be undertaken. Part of those processes would require environmental baseline studies and site analysis, including benthic, acoustic and wave resource characterization. The MOTB and its myriad systems would need to be designed and constructed.The first WEC test at the facility with the MOTB was completed within this project with the WET-NZ device in summer 2012. In summer 2013, the MOTB was deployed with load cells on its mooring lines to characterize forces on mooring systems in a variety of sea states. Throughout both testing seasons, studies were done to analyze environmental effects during testing operations. Test protocols and best management practices for open ocean operations were developed. As a result of this project, the non-grid connected fully energetic WEC test facility is operational, and the MOTB system developed provides a portable concept for WEC testing. The permitting process used provides a model for other wave energy projects, especially those in the Pacific Northwest that have similar

  12. Foldover, quasi-periodicity, spin-wave instabilities in ultra-thin films subject to RF fields

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)]. E-mail: mdaquino@unina.it; Bertotti, G. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Serpico, C. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States); Bonin, R. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Guida, G. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)

    2007-09-15

    We study magnetization dynamics in a uniaxial ultra-thin ferromagnetic disk subject to spatially uniform microwave external fields. The rotational invariance of the system is such that the only admissible spatially uniform steady states are periodic (P-modes) and quasi-periodic (Q-modes) modes. The stability of P-modes versus spatially uniform and nonuniform perturbations is studied by using spin-wave analysis and the instability diagram for all possible P-modes is computed. The predictions of the spin-wave analysis are compared with micromagnetic simulations.

  13. Coupling between Current and Dynamic Magnetization : from Domain Walls to Spin Waves

    Science.gov (United States)

    Lucassen, M. E.

    2012-05-01

    So far, we have derived some general expressions for domain-wall motion and the spin motive force. We have seen that the β parameter plays a large role in both subjects. In all chapters of this thesis, there is an emphasis on the determination of this parameter. We also know how to incorporate thermal fluctuations for rigid domain walls, as shown above. In Chapter 2, we study a different kind of fluctuations: shot noise. This noise is caused by the fact that an electric current consists of electrons, and therefore has fluctuations. In the process, we also compute transmission and reflection coefficients for a rigid domain wall, and from them the linear momentum transfer. More work on fluctuations is done in Chapter 3. Here, we consider a (extrinsically pinned) rigid domain wall under the influence of thermal fluctuations that induces a current via spin motive force. We compute how the resulting noise in the current is related to the β parameter. In Chapter 4 we look into in more detail into the spin motive forces from field driven domain walls. Using micro magnetic simulations, we compute the spin motive force due to vortex domain walls explicitly. As mentioned before, this gives qualitatively different results than for a rigid domain wall. The final subject in Chapter 5 is the application of the general expression for spin motive forces to magnons. Although this might seem to be unrelated to domain-wall motion, this calculation allows us to relate the β parameter to macroscopic transport coefficients. This work was supported by Stichting voor Fundamenteel Onderzoek der Materie (FOM), the Netherlands Organization for Scientific Research (NWO), and by the European Research Council (ERC) under the Seventh Framework Program (FP7).

  14. Self-Calibrating Wave-Encoded Variable-Density Single-Shot Fast Spin Echo Imaging.

    Science.gov (United States)

    Chen, Feiyu; Taviani, Valentina; Tamir, Jonathan I; Cheng, Joseph Y; Zhang, Tao; Song, Qiong; Hargreaves, Brian A; Pauly, John M; Vasanawala, Shreyas S

    2018-04-01

    It is highly desirable in clinical abdominal MR scans to accelerate single-shot fast spin echo (SSFSE) imaging and reduce blurring due to T 2 decay and partial-Fourier acquisition. To develop and investigate the clinical feasibility of wave-encoded variable-density SSFSE imaging for improved image quality and scan time reduction. Prospective controlled clinical trial. With Institutional Review Board approval and informed consent, the proposed method was assessed on 20 consecutive adult patients (10 male, 10 female, range, 24-84 years). A wave-encoded variable-density SSFSE sequence was developed for clinical 3.0T abdominal scans to enable high acceleration (3.5×) with full-Fourier acquisitions by: 1) introducing wave encoding with self-refocusing gradient waveforms to improve acquisition efficiency; 2) developing self-calibrated estimation of wave-encoding point-spread function and coil sensitivity to improve motion robustness; and 3) incorporating a parallel imaging and compressed sensing reconstruction to reconstruct highly accelerated datasets. Image quality was compared pairwise with standard Cartesian acquisition independently and blindly by two radiologists on a scale from -2 to 2 for noise, contrast, confidence, sharpness, and artifacts. The average ratio of scan time between these two approaches was also compared. A Wilcoxon signed-rank tests with a P value under 0.05 considered statistically significant. Wave-encoded variable-density SSFSE significantly reduced the perceived noise level and improved the sharpness of the abdominal wall and the kidneys compared with standard acquisition (mean scores 0.8, 1.2, and 0.8, respectively, P variable-density sampling SSFSE achieves improved image quality with clinically relevant echo time and reduced scan time, thus providing a fast and robust approach for clinical SSFSE imaging. 1 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:954-966. © 2017 International Society for Magnetic Resonance in Medicine.

  15. Coulomb singularities in scattering wave functions of spin-orbit-coupled states

    International Nuclear Information System (INIS)

    Bogdanski, P.; Ouerdane, H.

    2011-01-01

    We report on our analysis of the Coulomb singularity problem in the frame of the coupled channel scattering theory including spin-orbit interaction. We assume that the coupling between the partial wave components involves orbital angular momenta such that Δl= 0, ±2. In these conditions, the two radial functions, components of a partial wave associated to two values of the angular momentum l, satisfy a system of two second-order ordinary differential equations. We examine the difficulties arising in the analysis of the behavior of the regular solutions near the origin because of this coupling. First, we demonstrate that for a singularity of the first kind in the potential, one of the solutions is not amenable to a power series expansion. The use of the Lippmann-Schwinger equations confirms this fact: a logarithmic divergence arises at the second iteration. To overcome this difficulty, we introduce two auxilliary functions which, together with the two radial functions, satisfy a system of four first-order differential equations. The reduction of the order of the differential system enables us to use a matrix-based approach, which generalizes the standard Frobenius method. We illustrate our analysis with numerical calculations of coupled scattering wave functions in a solid-state system.

  16. Investigation of the stationary state of parametric spin waves in antiferromagnetics by the modulation technique

    International Nuclear Information System (INIS)

    Andrienko, A.V.; Safonov, V.L.; Yakubovskij, A.Yu.

    1987-01-01

    The response of parametric electron and nuclear spin waves to weak modulation of a stationary magnetic field is investigated in the antiferromagnetics MnCO 3 and CsMnF 3 . The modulation response is calculated by taking into accout the phase mechanism of restriction of the parametric wave amplitude and positive nonlinear attenuation of the waves. Some characteristics of the stationary state of parametric electron and nuclear magnons are determined within the framework of the model by analysis of the experimental results: the nonlinear magnon interaction coefficient S k and the parameter κ which characterizes the relative contribution from positive nonlinear attenuation and the phase mechanism to the restriction of the number of parametric magnons. An anomaly in the behavior of the modulation response of the parametric nuclear magnons is observed in CsMnF 3 ; this is manifest in asubstantial decrease of the modulation response in a narrow supercriticality and modulation frequency range. A giant hexagonal anisotropy of the modulation response and nonlinear dynamic susceptibility of the nuclear magnons is observed in the same crystal. This may indicate a nonisotropic distribution of the magnons in k-space

  17. Spin wave collapse and incommensurate fluctuations in URu2Si2

    DEFF Research Database (Denmark)

    Buyers, W.J.L.; Tun, Z.; Petersen, T.

    1994-01-01

    To test if the T(N) = 17.7 K transition in URu2Si2 is driven by a divergence of a magnetic order parameter we performed high-resolution neutron scattering. At the ordering wave vector the spin-wave energy collapsed. and the susceptibility diverged as T(N) was approached. This confirms that the or...... that the order parameter is the magnetic dipole, as shown by recent symmetry arguments and polarized neutron experiments [1]. We also observe incommensurate fluctuations, suggesting that competing temperature-dependent interactions may influence this weak-moment transition.......To test if the T(N) = 17.7 K transition in URu2Si2 is driven by a divergence of a magnetic order parameter we performed high-resolution neutron scattering. At the ordering wave vector the spin-wave energy collapsed. and the susceptibility diverged as T(N) was approached. This confirms...

  18. Control of propagation characteristics of spin wave pulses via elastic and thermal effects

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Arista, Ivan [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Kolokoltsev, O., E-mail: oleg.kolokoltsev@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Acevedo, A.; Qureshi, N. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Ordóñez-Romero, César L. [Instituto de Física, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico)

    2017-05-01

    A study of the magnetoelastic (ME) and thermal effects governing the phase (φ) and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides is presented. The ME effects were studied in a flexural configuration, under punctual mechanical force (F). Thermally induced ME and demagnetization phenomena were controlled by optically injected thermal power P{sub th}. It was determined that in an unclamped Ga:YIG waveguide, the force F that induces the phase shift Δφ=π, decreases by a quadratic law in the range from 1 mN to nN, and the P{sub th} at which Δφ=π decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. For nano-volume waveguides the ME control energy (E{sub me}) can be of order of aJ, and the thermal control energy (ΔE{sub th}) can be as small as 50 fJ. The response time of these effects lies in the ns time scale. Both the mechanical and the thermo-magnetic forces provide an effective control of MSSW pulse amplitude, in addition to its phase shift. The thermo-magnetic effect allows one to realize variable delays of a MSSW pulse. - Highlights: • The Magneto-elastic (ME) and optically induced thermal effects governing the phase and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides are presented. • A mechanical force that causes phase shift Δφ=π for spin waves in the waveguides decreases by a quadratic law in the range from 1 mN to nN, and the optical power that induces the phase shift Δφ=π, decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. • The response time of these effects can lie in the ns time scale.

  19. Polarization study of non-resonant X-ray magnetic scattering from spin-density-wave modulation in chromium

    International Nuclear Information System (INIS)

    Ohsumi, Hiroyuki; Takata, Masaki

    2007-01-01

    We present a polarization study of non-resonant X-ray magnetic scattering in pure chromium. Satellite reflections are observed at +/-Q and +/-2Q, where Q is the modulation wave vector of an itinerant spin-density-wave. The first and second harmonics are confirmed to have magnetic and charge origin, respectively, by means of polarimetry without using an analyzer crystal. This alternative technique eliminates intolerable intensity loss at an analyzer by utilizing the sample crystal also as an analyzer crystal

  20. Enhanced spin wave propagation in magnonic rings by bias field modulation

    Science.gov (United States)

    Venkat, G.; Venkateswarlu, D.; Joshi, R. S.; Franchin, M.; Fangohr, H.; Anil Kumar, P. S.; Prabhakar, A.

    2018-05-01

    We simulate the spin wave (SW) dynamics in ring structures and obtain the ω - k dispersion relations corresponding to the output waveguide. Different bias field configurations affect the transfer of SW power from one arm of the structure to the other arm. To this end, we show that circular or radial bias fields are more suitable for energy transfer across the ring than the conventional horizontal bias field Hx. The SW dispersion shows that modes excited, when the bias field is along the ring radius, are almost 10 dB higher in power when compared to the modal power in the case of Hx. This is also corroborated by the SW energy density in the receiving stub.

  1. Spin-wave dispersion relations in disordered Fe-V alloys

    International Nuclear Information System (INIS)

    Nakai, Y.; Schibuya, N.; Kunitomi, N.; Wakabayashi, N.; Cooke, J.F.

    1982-01-01

    The spin-wave dispersion relations of the ferromagnetic disordered alloys Fe/sub 1-x/V/sub x/(x = 0.076, 0.135, 0.160, and 0.187) were studied by means of the inelastic scattering of neutrons. The observed dispersion relations are adequately represented by the power law, E = Dq 2 (1-βq 2 ), in a wide energy range up to 80 meV. The concentration dependence of the exchange stiffness constant D shows good agreement with previous results obtained by means of the small-angle scattering of neutrons and by the analysis of the temperature dependence of the bulk magnetization. The observed results can be explained by the Heisenberg model and, to some extent, by the itinerant-electron model

  2. Ferromagnetic resonance and spin-wave resonances in GaMnAsP films

    Science.gov (United States)

    Liu, Xinyu; Li, Xiang; Bac, Seul-Ki; Zhang, Xucheng; Dong, Sining; Lee, Sanghoon; Dobrowolska, Margaret; Furdyna, Jacek K.

    2018-05-01

    A series of Ga1-xMnxAs1-yPy films grown by MBE on GaAs (100) substrates was systematically studied by ferromagnetic resonance (FMR). Magnetic anisotropy parameters were obtained by analyzing the angular dependence of the FMR data. The results clearly show that the easy axis of the films shifts from the in-plane [100] direction to the out-of-plane [001], indicating the emergence of a strong tensile-strain-induced perpendicular anisotropy when the P content exceeds y ≈ 0.07. Multiple resonances were observed in Ga1-xMnxAs1-yPy films with thicknesses over 48 nm, demonstrating the existence of exchange-dominated non-propagating spin-wave modes governed by surface anisotropy.

  3. Spin wave propagation in perpendicularly magnetized nm-thick yttrium iron garnet films

    Science.gov (United States)

    Chen, Jilei; Heimbach, Florian; Liu, Tao; Yu, Haiming; Liu, Chuanpu; Chang, Houchen; Stückler, Tobias; Hu, Junfeng; Zeng, Lang; Zhang, Youguang; Liao, Zhimin; Yu, Dapeng; Zhao, Weisheng; Wu, Mingzhong

    2018-03-01

    Magnonics offers a new way for information transport that uses spin waves (SWs) and is free of charge currents. Unlike Damon-Eshbach SWs, the magneto-static forward volume SWs offer the reciprocity configuration suitable for SW logic devices with low power consumption. Here, we study forward volume SW propagation in yttrium iron garnet (YIG) thin films with an ultra-low damping constant α = 8 ×10-5 . We design different integrated microwave antenna with different k-vector excitation distributions on YIG thin films. Using a vector network analyzer, we measured SW transmission with the films magnetized in perpendicular orientation. Based on the experimental results, we extract the group velocity as well as the dispersion relation of SWs and directly compare the power efficiency of SW propagation in YIG using coplanar waveguide and micro stripline for SW excitation and detection.

  4. Tunneling Conductance in Ferromagnetic Metal/Normal Metal/Spin-Singlet -Wave Ferromagnetic Superconductor Junctions

    Directory of Open Access Journals (Sweden)

    Hamidreza Emamipour

    2013-01-01

    Full Text Available In the framework of scattering theory, we study the tunneling conductance in a system including two junctions, ferromagnetic metal/normal metal/ferromagnetic superconductor, where ferromagnetic superconductor is in spin-singlet -wave pairing state. The non-magnetic normal metal is placed in the intermediate layer with the thickness ( which varies from 1 nm to 10000 nm. The interesting result which we have found is the existence of oscillations in conductance curves. The period of oscillations is independent of FS and FN exchange field while it depends on . The obtained results can serve as a useful tool to determine the kind of pairing symmetry in ferromagnetic superconductors.

  5. Integrable open spin chain in Super Yang-Mills and the plane-wave/SYM duality

    International Nuclear Information System (INIS)

    Chen Bin; Wang Xiaojun; Wu Yongshi

    2004-01-01

    We investigate the integrable structures in an N = 2 superconfomal Sp(N) Yang-Mills theory with matter, which is dual to an open+closed string system. We restrict ourselves to the BMN operators that correspond to free string states. In the closed string sector, an integrable structure is inherited from its parent theory, N = 4 SYM. For the open string sector, the planar one-loop mixing matrix for gauge invariant holomorphic operators is identified with the Hamiltonian of an integrable SU(3) open spin chain. Using the K-matrix formalism we identify the integrable open-chain boundary conditions that correspond to string boundary conditions. The solutions to the algebraic Bethe ansatz equations (ABAE) with a few impurities are shown to recover the anomalous dimensions that exactly match the spectrum of free open string in the plane-wave background. We also discuss the properties of the solutions of ABAE beyond the BMN regime. (author)

  6. Galvanomagnetic properties in the spin-density-wave phase of (TMTSF)2PF6

    International Nuclear Information System (INIS)

    Korin-Hamzic, B.; Bechgaard, K.

    1999-01-01

    We have measured the magnetoresistance and the Hall effect in the spin-density-wave (SDW) state of (TMTSF) 2 PF 6 down to 2 K and in magnetic fields up to 9 T in order to gain an additional insight into the nature of the possible subphases in the SDW state. We have found that the temperature dependent magnetoresistance anisotropy changes below 4 K; this change being maximal for the current in the lowest conductivity direction. The Hall resistivity has showed different magnetic field dependencies for T>4 K and T<4 K. The resistivity and the Hall resistivity were also investigated as the function of the electric field. The backflow coefficient α does not change below 4 K. (orig.)

  7. Magnetic studies of spin wave excitations in Ni/Au multilayers

    International Nuclear Information System (INIS)

    Salhi, H.; Chafai, K.; Benkirane, K.; Lassri, H.; Abid, M.; Hlil, E.K.

    2010-01-01

    Ni/Au multilayers were prepared by the electron beam evaporation method under ultra high vacuum conditions. The multilayer films have a coherent structure with (1 1 1) texture. The magnetic properties of Ni/Au multilayers are examined as a function of Ni layer thickness t Ni . The temperature dependence of the spontaneous magnetization M(T) is well described by a T 3/2 law in all multilayers. A spin wave theory has been used to explain the magnetization versus temperature. Based on this theory, the approximate values for the bulk exchange interaction J b , surface exchange interaction J S and the interlayer coupling strength J I have been obtained for various Ni layer thicknesses.

  8. Dual Band Magnonic Crystals: Model System and Basic Spin Wave Dynamics

    Directory of Open Access Journals (Sweden)

    Federico Montoncello

    2016-01-01

    Full Text Available We investigate a special design of two-dimensional magnonic crystal, consisting of two superimposed lattices with different lattice constants, such that spin waves (SWs can propagate either in one or the other sublattice, depending on which of the two frequency bands they belong to. The SW bands are separated by a very large bandgap (in our model system, 6 GHz, easily tunable by changing the direction of an applied magnetic field, and the overlap of their spatial distribution, for any frequency of their bands, is always negligible. These properties make the designed system an ideal test system for a magnonic dual band waveguide, where the simultaneous excitation and subsequent propagation of two independent SW signals are allowed, with no mutual interference.

  9. Long-range spin wave mediated control of defect qubits in nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Andrich, Paolo; de las Casas, Charles F.; Liu, Xiaoying; Bretscher, Hope L.; Berman, Jonson R.; Heremans, F. Joseph; Nealey, Paul F.; Awschalom, David D.

    2017-07-17

    Hybrid architectures that combine nitrogen-vacancy (NV) centers in diamond with other materials and physical systems have been proposed to enhance the NV center’s capabilities in many quantum sensing and information applications. In particular, spin waves (SWs) in ferromagnetic materials are a promising candidate to implement these platforms due to their strong magnetic fields, which could be used to efficiently interact with the NV centers. Here we develop an yttrium iron garnet-nanodiamond hybrid architecture constructed with the help of directed assembly and transfer printing techniques. Operating at ambient conditions, we demonstrate that surface confined SWs excited in the ferromagnet (FM) can strongly amplify the interactions between a microwave source and the NV centers by enhancing the local microwave magnetic field by several orders of magnitude. Crucially, we show the existence of a regime in which coherent interactions between SWs and NV centers dominate over incoherent mechanisms associated with the broadband magnetic field noise generated by the FM. These accomplishments enable the SW mediated coherent control of spin qubits over distances larger than 200 um, and allow low power operations for future spintronic technologies.

  10. Anomalous spin waves and the commensurate-incommensurate magnetic phase transition in LiNiPO4

    DEFF Research Database (Denmark)

    Jensen, Thomas Bagger Stibius; Christensen, Niels Bech; Kenzelmann, M.

    2009-01-01

    Detailed spin-wave spectra of magnetoelectric LiNiPO4 have been measured by neutron scattering at low temperatures in the commensurate (C) antiferromagnetic (AF) phase below T-N=20.8 K. An anomalous shallow minimum is observed at the modulation vector of the incommensurate (IC) AF phase appearing...

  11. Inelastic neutron scattering in the spin wave energy gap of the polydomain γ-Mn(12%Ge) alloy

    International Nuclear Information System (INIS)

    Jankowska-Kisielinska, J.; Mikke, K.

    1999-01-01

    The subject of the present experiment was the investigation of the inelastic neutron scattering (INS) for energy transfers lower than and close to the energy gap of the spin wave spectrum for long wavelengths. The aim was a search for the excitations at the magnetic Brillouin zone (MBZ) boundary in polydomain Mn(12%Ge) alloy. The present measurements were performed by a 3-axis spectrometer at Maria Reactor at IEA in Swierk. We observed the INS in the polydomain Mn(12%Ge) alloy for energies smaller than and close to the energy gap value of the spin wave spectrum at room temperature. The observed intensity can be treated as a sum of intensity of neutrons scattered on spin waves around magnetic Brillouin zone centre and that of neutrons scattered on fluctuations at the zone boundary. The intensity of both components for energies 2-6 MeV was found to be of the same order. For higher energies spin waves around magnetic zone centre dominate. (author)

  12. Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

    Science.gov (United States)

    Siegfried, S.-A.; Sukhanov, A. S.; Altynbaev, E. V.; Honecker, D.; Heinemann, A.; Tsvyashchenko, A. V.; Grigoriev, S. V.

    2017-04-01

    We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225 K up to TC≈278.7 K by small-angle neutron scattering. The method we have used is based on [Grigoriev et al., Phys. Rev. B 92, 220415(R) (2015), 10.1103/PhysRevB.92.220415] and was extended here for the application in polycrystalline samples. We confirm the validity of the anisotropic spin-wave dispersion for FeGe caused by the Dzyaloshinskii-Moriya interaction. We have shown that the spin-wave stiffness A for the FeGe helimagnet decreases with a temperature as A (T ) =194 [1 -0.7 (T/TC) 4.2] meVÅ 2 . The finite value of the spin-wave stiffness A =58 meVÅ 2 at TC classifies the order-disorder phase transition in FeGe as being the first-order one.

  13. Effects of disorder on atomic density waves and spin-singlet dimers in one-dimensional optical lattices

    International Nuclear Information System (INIS)

    Gao Xianlong

    2008-01-01

    Using the Bethe-ansatz density-functional theory, we study a one-dimensional Hubbard model of confined attractively interacting fermions in the presence of a uniformly distributed disorder. The strongly correlated Luther-Emery nature of the attractive one-dimensional Hubbard model is fully taken into account as the reference system in the density-functional theory. The effects of the disorder are investigated on the atomic density waves in the weak-to-intermediate attractive interaction and on the spin-singlet dimers of doubly occupied sites in the strongly attractive regime. It is found that atomic density waves are sensitive to the disorder and the spin-singlet dimers of doubly occupied sites are quite unstable against the disorder. We also show that a very weak disorder could smear the singularities in the stiffness, thus, suppresses the spin-singlet pairs

  14. Angstrom-Resolution Magnetic Resonance Imaging of Single Molecules via Wave-Function Fingerprints of Nuclear Spins

    Science.gov (United States)

    Ma, Wen-Long; Liu, Ren-Bao

    2016-08-01

    Single-molecule sensitivity of nuclear magnetic resonance (NMR) and angstrom resolution of magnetic resonance imaging (MRI) are the highest challenges in magnetic microscopy. Recent development in dynamical-decoupling- (DD) enhanced diamond quantum sensing has enabled single-nucleus NMR and nanoscale NMR. Similar to conventional NMR and MRI, current DD-based quantum sensing utilizes the "frequency fingerprints" of target nuclear spins. The frequency fingerprints by their nature cannot resolve different nuclear spins that have the same noise frequency or differentiate different types of correlations in nuclear-spin clusters, which limit the resolution of single-molecule MRI. Here we show that this limitation can be overcome by using "wave-function fingerprints" of target nuclear spins, which is much more sensitive than the frequency fingerprints to the weak hyperfine interaction between the targets and a sensor under resonant DD control. We demonstrate a scheme of angstrom-resolution MRI that is capable of counting and individually localizing single nuclear spins of the same frequency and characterizing the correlations in nuclear-spin clusters. A nitrogen-vacancy-center spin sensor near a diamond surface, provided that the coherence time is improved by surface engineering in the near future, may be employed to determine with angstrom resolution the positions and conformation of single molecules that are isotope labeled. The scheme in this work offers an approach to breaking the resolution limit set by the "frequency gradients" in conventional MRI and to reaching the angstrom-scale resolution.

  15. 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.

  16. A possible scheme for measuring gravitational waves by using a spinful quantum fluid

    Directory of Open Access Journals (Sweden)

    Cheng Yao

    2014-06-01

    Full Text Available A method is proposed for measuring gravitational waves (GWs from the collective electromagnetic (EM response of a spinful quantum fluid, based on recent studies of the long-lived Mössbauer state 93mNb in a pure Nb crystal. A pronounced EM response was found for the geometric phase by rotating the sample in a magnetic field, suggesting that GWs could also be detected. It was recently suggested that the macroscopic wave functions confined in two twisted nonspherical superconductors would give a geometrical phase oscillation induced by GWs. The sensitivity to GWs would be inversely proportional to the square of the bound length, which is the detector size. The proposed sensitivity to GWs would be dramatically enhanced by changing the characteristic size, i.e., using the microscopic size of a non-spherical particle instead of the macroscopic detector size of a scalar quantum fluid. The collective EM response from the quantum fluid would allow the macroscopic geometrical phase to be read from microscopic particles. GWs in the millihertz range, with amplitude of 10−22, would be detectable.

  17. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    International Nuclear Information System (INIS)

    Gruszecki, P.; Krawczyk, M.; Romero-Vivas, J.; Dadoenkova, Yu. S.; Dadoenkova, N. N.; Lyubchanskii, I. L.

    2014-01-01

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale

  18. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Gruszecki, P., E-mail: pawel.gruszecki@amu.edu.pl; Krawczyk, M., E-mail: krawczyk@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, Poznań 61-614 (Poland); Romero-Vivas, J. [Department of Electronic and Computer Engineering, University of Limerick, Limerick (Ireland); Dadoenkova, Yu. S.; Dadoenkova, N. N. [Donetsk Physical and Technical Institute of the National Academy of Sciences of Ukraine, 83114 Donetsk (Ukraine); Ulyanovsk State University, 42 Leo Tolstoy str., 432000 Ulyanovsk (Russian Federation); Lyubchanskii, I. L. [Donetsk Physical and Technical Institute of the National Academy of Sciences of Ukraine, 83114 Donetsk (Ukraine)

    2014-12-15

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

  19. Spin density waves predicted in zigzag puckered phosphorene, arsenene and antimonene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaohua; Zhang, Xiaoli; Wang, Xianlong [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zeng, Zhi, E-mail: zzeng@theory.issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China)

    2016-04-15

    The pursuit of controlled magnetism in semiconductors has been a persisting goal in condensed matter physics. Recently, Vene (phosphorene, arsenene and antimonene) has been predicted as a new class of 2D-semiconductor with suitable band gap and high carrier mobility. In this work, we investigate the edge magnetism in zigzag puckered Vene nanoribbons (ZVNRs) based on the density functional theory. The band structures of ZVNRs show half-filled bands crossing the Fermi level at the midpoint of reciprocal lattice vectors, indicating a strong Peierls instability. To remove this instability, we consider two different mechanisms, namely, spin density wave (SDW) caused by electron-electron interaction and charge density wave (CDW) caused by electron-phonon coupling. We have found that an antiferromagnetic Mott-insulating state defined by SDW is the ground state of ZVNRs. In particular, SDW in ZVNRs displays several surprising characteristics:1) comparing with other nanoribbon systems, their magnetic moments are antiparallelly arranged at each zigzag edge and almost independent on the width of nanoribbons; 2) comparing with other SDW systems, its magnetic moments and band gap of SDW are unexpectedly large, indicating a higher SDW transition temperature in ZVNRs; 3) SDW can be effectively modified by strains and charge doping, which indicates that ZVNRs have bright prospects in nanoelectronic device.

  20. Spin density waves predicted in zigzag puckered phosphorene, arsenene and antimonene nanoribbons

    Directory of Open Access Journals (Sweden)

    Xiaohua Wu

    2016-04-01

    Full Text Available The pursuit of controlled magnetism in semiconductors has been a persisting goal in condensed matter physics. Recently, Vene (phosphorene, arsenene and antimonene has been predicted as a new class of 2D-semiconductor with suitable band gap and high carrier mobility. In this work, we investigate the edge magnetism in zigzag puckered Vene nanoribbons (ZVNRs based on the density functional theory. The band structures of ZVNRs show half-filled bands crossing the Fermi level at the midpoint of reciprocal lattice vectors, indicating a strong Peierls instability. To remove this instability, we consider two different mechanisms, namely, spin density wave (SDW caused by electron-electron interaction and charge density wave (CDW caused by electron-phonon coupling. We have found that an antiferromagnetic Mott-insulating state defined by SDW is the ground state of ZVNRs. In particular, SDW in ZVNRs displays several surprising characteristics:1 comparing with other nanoribbon systems, their magnetic moments are antiparallelly arranged at each zigzag edge and almost independent on the width of nanoribbons; 2 comparing with other SDW systems, its magnetic moments and band gap of SDW are unexpectedly large, indicating a higher SDW transition temperature in ZVNRs; 3 SDW can be effectively modified by strains and charge doping, which indicates that ZVNRs have bright prospects in nanoelectronic device.

  1. Light Spins of Cylindrical Electromagnetic Waves and their Jumps across Material Interfaces in the Presence of Energy Exchange

    Directory of Open Access Journals (Sweden)

    J. Mok

    2016-08-01

    Full Text Available We investigate light spins for cylindrical electromagnetic waves on resonance. To this goal, we consider both a dielectric cylinder of infinite length immersed in vacuum and a cylindrical hole punched through a dense dielectric medium. In order for waves of constant frequencies to be established through lossless media, energy absorption is allowed in the surrounding medium to compensate for radiation loss. The dispersion relation is then numerically solved for an asymmetry parameter implying a balance in energy exchange. Numerical studies are performed by varying parameters of refractive index contrast, azimuthal mode index, and size parameter of a cylindrical object. The resulting data is presented mostly in terms of a specific spin, defined as light spin per energy density. This specific spin is found to be bounded in its magnitude, with its maximum associated with either optical vortices or large rotations. Depending on parametric combinations, the specific spin could not only undergo finite jumps across the material interface but also exhibit limit behaviors.

  2. Research on the development of the centrifugal spinning

    Directory of Open Access Journals (Sweden)

    Zhang Zhiming

    2017-01-01

    Full Text Available Centrifugal spinning is a new and efficient method to produce nanofibers quickly. It makes use of the centrifugal force instead of high voltage to produce the nanofibers. The centrifugal spinning has many advantages such as no high voltage, high yield, simple structure, no pollution and can be applied to high polymer material, ceramic and metal material. In order to have more understand about this novel nanofibers formation method, this paper introduces the method of centrifugal spinning and the effect of rotation speed, the properties of material such as viscosity and solvent evaporation, collector distance which have an impact on nanofibers morphology and diameter were also analyzed.

  3. Charge transport in 2DEG/s-wave superconductor junction with Dresselhaus-type spin-orbit coupling

    International Nuclear Information System (INIS)

    Sawa, Y.; Yokoyama, T.; Tanaka, Y.

    2007-01-01

    We study spin-dependent charge transport in superconducting junctions. We consider ballistic two-dimensional electron gas (2DEG)/s-wave superconductor junctions with Dresselhaus-type spin-orbit coupling (DSOC). We calculate the conductance normalized by that in the normal state of superconductor in order to study the effect of DSOC in 2DEG on conductance, changing the height of insulating barrier. We find the DSOC suppresses the conductance for low insulating barrier, while it can slightly enhance the conductance for high insulating barrier. It has a reentrant dependence on DSOC for middle strength insulating barrier. The effect of DSOC is weaken as the insulating barrier becomes high

  4. Magnon Accumulation by Clocked Laser Excitation as Source of Long-Range Spin Waves in Transparent Magnetic Films

    Directory of Open Access Journals (Sweden)

    M. Jäckl

    2017-04-01

    Full Text Available Optical tools are promising for spin-wave generation because of the possibilities of ultrafast manipulation and local excitation. However, a single laser pulse can inject spin waves (SWs only with a broad frequency spectrum, resulting in short propagation distances and low wave amplitudes. Here, we excite a magnetic garnet film by a train of fs-laser pulses with a 1-GHz repetition rate so that the pulse separation is shorter than the decay time of magnetic modes, which allows us to achieve a collective impact on the magnetization and establish a quasistationary source of spin waves, namely, a coherent accumulation of magnons (“magnon cloud”. This approach has several appealing features: (i The magnon source is tunable, (ii the SW amplitude can be significantly enhanced, (iii the SW spectrum is quite narrow, providing long-distance propagation, (iv the periodic pumping results in an almost constant-in-time SW amplitude for the distances larger than 20  μm away from the source, and (v the SW emission shows pronounced directionality. These results expand the capabilities of ultrafast coherent optical control of magnetization and pave the way for applications in data processing, including the quantum regime. The quasistationary magnon accumulation might also be of interest for applications in magnon Bose-Einstein condensates.

  5. New materials research for high spin polarized current

    International Nuclear Information System (INIS)

    Tezuka, Nobuki

    2012-01-01

    The author reports here a thorough investigation of structural and magnetic properties of Co 2 FeAl 0.5 Si 0.5 Heusler alloy films, and the tunnel magnetoresistance effect for junctions with Co 2 FeAl 0.5 Si 0.5 electrodes, spin injection into GaAs semiconductor from Co 2 FeAl 0.5 Si 0.5 , and spin filtering phenomena for junctions with CoFe 2 O 4 ferrite barrier. It was observed that tunnel magnetoresistance ratio up to 832%(386%) at 9 K (room temperature), which corresponds to the tunnel spin polarization of 0.90 (0.81) for the junctions using Co 2 FeAl 0.5 Si 0.5 Heusler electrodes by optimizing the fabrication condition. It was also found that the tunnel magnetoresistance ratio are almost the same between the junctions with Co 2 FeAl 0.5 Si 0.5 Heusler electrodes on Cr buffered (1 0 0) and (1 1 0) MgO substrates, which indicates that tunnel spin polarization of Co 2 FeAl 0.5 Si 0.5 for these two direction are almost the same. The next part of this paper is a spin filtering effect using a Co ferrite. The spin filtering effect was observed through a thin Co-ferrite barrier. The inverse type tunnel magnetoresistance ratio of −124% measured at 10 K was obtained. The inverse type magnetoresistance suggests the negative spin polarization of Co-ferrite barrier. The magnetoresistance ratio of −124% corresponds to the spin polarization of −0.77 by the Co-ferrite barrier. The last part is devoted to the spin injection from Co 2 FeAl 0.5 Si 0.5 into GaAs. The spin injection signal was clearly obtained by three terminal Hanle measurement. The spin relaxation time was estimated to be 380 ps measured at 5 K.

  6. Azimuthally spinning wave modes and heat release in an annular combustor

    Science.gov (United States)

    Nygard, Hakon; Mazur, Marek; Dawson, James R.; Worth, Nicholas A.

    2017-11-01

    In order to reduce NOx emissions from aeroengines and stationary gas turbines the fuel-air mixture can be made leaner, at the risk of introducing potentially damaging thermo-acoustic instabilities. At present this phenomenon is not understood well enough to eliminate these instabilities at the design stage. Recently, the presence of different azimuthal modes in annular combustors has been demonstrated both experimentally and numerically. These naturally occurring instabilities in annular geometry have been observed to constantly switch between spinning and standing modes, making it more difficult to analyse the flame structure and dynamics. Very recently this issue was partially addressed using novel acoustic forcing to generate a standing mode. In the present study this concept has been developed further by creating an azimuthal array of loud speakers, which for the first time permits predominantly spinning modes to be set up inside the combustion chamber. The use of pressure and high speed OH* measurements enables the study of the flame dynamics and heat release rate oscillations of the combustor, which will be reported in the current paper. The ability to precisely control the azimuthal mode of oscillation greatly enhances our further understanding of the phenomenon. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No 677931 TAIAC).

  7. Electric-field tunable spin waves in PMN-PT/NiFe heterostructure: Experiment and micromagnetic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ziȩtek, Slawomir, E-mail: zietek@agh.edu.pl [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Chȩciński, Jakub [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059 Kraków (Poland); Frankowski, Marek; Skowroński, Witold; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland)

    2017-04-15

    We present a comprehensive theoretical and experimental study of voltage-controlled standing spin waves resonance (SSWR) in PMN-PT/NiFe multiferroic heterostructures patterned into microstrips. A spin-diode technique was used to observe ferromagnetic resonance (FMR) mode and SSWR in NiFe strip mechanically coupled with a piezoelectric substrate. Application of an electric field to a PMN-PT creates a strain in permalloy and thus shifts the FMR and SSWR fields due to the magnetostriction effect. The experimental results are compared with micromagnetic simulations and a good agreement between them is found for dynamics of FMR and SSWR with and without electric field. Moreover, micromagnetic simulations enable us to discuss the amplitude and phase spatial distributions of FMR and SSWR modes, which are not directly observable by means of spin diode detection technique.

  8. Spin wave eigenmodes in single and coupled sub-150 nm rectangular permalloy dots

    Energy Technology Data Exchange (ETDEWEB)

    Carlotti, G., E-mail: giovanni.carlotti@fisica.unipg.it; Madami, M. [Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Tacchi, S. [Istituto Officina dei Materiali del CNR (CNR-IOM), Dipartimento di Fisica e Geologia, Perugia (Italy); Gubbiotti, G.; Dey, H.; Csaba, G.; Porod, W. [Center for Nano Science and Technology, Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2015-05-07

    We present the results of a Brillouin light scattering investigation of thermally excited spin wave eigenmodes in square arrays of either isolated rectangular dots of permalloy or twins of dipolarly coupled elements, placed side-by-side or head-to-tail. The nanodots, fabricated by e-beam lithography and lift-off, are 20 nm thick and have the major size D in the range between 90 nm and 150 nm. The experimental spectra show the presence of two main peaks, corresponding to modes localized either at the edges or in the center of the dots. Their frequency dependence on the dot size and on the interaction with adjacent elements has been measured and successfully interpreted on the basis of dynamical micromagnetic simulations. The latter enabled us also to describe the spatial profile of the eigenmodes, putting in evidence the effects induced by the dipolar interaction between coupled dots. In particular, in twinned dots the demagnetizing field is appreciably modified in proximity of the “internal edges” if compared to the “external” ones, leading to a splitting of the edge mode. These results can be relevant for the exploitation of sub-150 nm magnetic dots in new applications, such as magnonic metamaterials, bit-patterned storage media, and nano-magnetic logic devices.

  9. First Higher-Multipole Model of Gravitational Waves from Spinning and Coalescing Black-Hole Binaries.

    Science.gov (United States)

    London, Lionel; Khan, Sebastian; Fauchon-Jones, Edward; García, Cecilio; Hannam, Mark; Husa, Sascha; Jiménez-Forteza, Xisco; Kalaghatgi, Chinmay; Ohme, Frank; Pannarale, Francesco

    2018-04-20

    Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipoles (ℓ=2,|m|=2) of the radiation during inspiral, merger, and ringdown. We introduce a simple method to include the subdominant multipoles to binary black hole gravitational waveforms, given a frequency-domain model for the dominant multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two. No additional tuning to numerical-relativity simulations is required. We apply a variant of this method to the nonprecessing PhenomD model. The result, PhenomHM, constitutes the first higher-multipole model of spinning and coalescing black-hole binaries, and currently includes the (ℓ,|m|)=(2,2),(3,3),(4,4),(2,1),(3,2),(4,3) radiative moments. Comparisons with numerical-relativity waveforms demonstrate that PhenomHM is more accurate than dominant-multipole-only models for all binary configurations, and typically improves the measurement of binary properties.

  10. Moessbauer spectra studied of spin-wave excitation for amorphous alloys

    International Nuclear Information System (INIS)

    Huang Zhigao

    1992-01-01

    The average hyperfine fields of amorphous Fe 70 Co 20 Zr 10 , Fe 80 Co 10 Zr 10 and Fe 86 Co 4 -Zr 10 alloys at different temperature were measured by the Moessbauer technique. According to Bloch's T 3/2 relation, spin-wave excitations of above amorphous alloys were studied and their B 3/2 values were found to be 0.40 +- 0.02, 0.45 +- 0.02 and 0.88 +- 0.04, respectively. Comparing the B 3/2 values of crystals, a-Fe-(Co, Ni)-ME, a-Fe-(Cr, Mn, W)-ME and a-Fe-B or TM-Zr invar alloys, the obvious difference among them was observed. Above results can be explained well by the exchange coupling fluctuation and the disorder of spatial arrangement. In this work, the difference between the stiffness coefficients obtained from the inelastic neutron scattering and the magnetization measurements for amorphous Invar alloys was also explained

  11. First Higher-Multipole Model of Gravitational Waves from Spinning and Coalescing Black-Hole Binaries

    Science.gov (United States)

    London, Lionel; Khan, Sebastian; Fauchon-Jones, Edward; García, Cecilio; Hannam, Mark; Husa, Sascha; Jiménez-Forteza, Xisco; Kalaghatgi, Chinmay; Ohme, Frank; Pannarale, Francesco

    2018-04-01

    Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipoles (ℓ=2 ,|m |=2 ) of the radiation during inspiral, merger, and ringdown. We introduce a simple method to include the subdominant multipoles to binary black hole gravitational waveforms, given a frequency-domain model for the dominant multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two. No additional tuning to numerical-relativity simulations is required. We apply a variant of this method to the nonprecessing PhenomD model. The result, PhenomHM, constitutes the first higher-multipole model of spinning and coalescing black-hole binaries, and currently includes the (ℓ,|m |)=(2 ,2 ),(3 ,3 ),(4 ,4 ),(2 ,1 ),(3 ,2 ),(4 ,3 ) radiative moments. Comparisons with numerical-relativity waveforms demonstrate that PhenomHM is more accurate than dominant-multipole-only models for all binary configurations, and typically improves the measurement of binary properties.

  12. General partial wave analysis of the decay of a hyperon of spin 1/2

    International Nuclear Information System (INIS)

    Lee, T.D.; Yang, C.N.

    1983-01-01

    This note is to consider the general problem of the decay of a hyperon of spin 1/2 into a pion and a nucleon under the general assumption of possible violations of parity conservation, charge-conjugation invariance, and time-reversal invariance. The discussion is in essence a partial wave analysis of the decay phenomena and is independent of the dynamics of the decay. Nonrelativistic approximations are not made on either of the decay products. In the reference system in which the hyperon is at rest there are two possible final states of the pion-nucleon system:s/sub 1/2/ and p/sub 1/2/. Denoting the amplitudes of these two states by A and B, one observes that the decay is physically characterized by three real constants specifying the magnitudes and the relative phase between these amplitudes. One of these constants can be taken to be absolute value a 2 + absolute value B 2 , and is evidently proportional to the decay probability per unit time. The other two constants are best defined in terms of experimentally measurable quantities. They discuss three types of experiments: (a) The angular distribution of the decay pion from a completely polarized hyperon at rest. (b) The longitudinal polarization of the nucleon emitted in the decay of unpolarized hyperons at rest. (c) Transverse polarization of the nucleon emitted in a given direction in the decay of a polarized hyperon

  13. Commensurate and incommensurate spin-density waves in heavy electron systems

    Directory of Open Access Journals (Sweden)

    P. Schlottmann

    2016-05-01

    Full Text Available The nesting of the Fermi surfaces of an electron and a hole pocket separated by a nesting vector Q and the interaction between electrons gives rise to itinerant antiferromagnetism. The order can gradually be suppressed by mismatching the nesting and a quantum critical point (QCP is obtained as the Néel temperature tends to zero. The transfer of pairs of electrons between the pockets can lead to a superconducting dome above the QCP (if Q is commensurate with the lattice, i.e. equal to G/2. If the vector Q is not commensurate with the lattice there are eight possible phases: commensurate and incommensurate spin and charge density waves and four superconductivity phases, two of them with modulated order parameter of the FFLO type. The renormalization group equations are studied and numerically integrated. A re-entrant SDW phase (either commensurate or incommensurate is obtained as a function of the mismatch of the Fermi surfaces and the magnitude of |Q − G/2|.

  14. Spin polarization driven by a charge-density wave in monolayer 1T−TaS2

    KAUST Repository

    Zhang, Qingyun

    2014-08-06

    Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer T-phase TaS2. We demonstrate that a charge-density wave is energetically favorable at low temperature, similar to bulk 1T-TaS2. Electron-phonon coupling is found to be essential for the lattice reconstruction. The charge-density wave results in a strong localization of the electronic states near the Fermi level and consequently in spin polarization, transforming the material into a magnetic semiconductor with enhanced electronic correlations. The combination of inherent spin polarization with a semiconducting nature distinguishes the monolayer fundamentally from the bulk compound as well as from other two-dimensional transition metal dichalcogenides. Monolayer T-phase TaS2 therefore has the potential to enable two-dimensional spintronics. © 2014 American Physical Society.

  15. Phase-dependent deterministic switching of magnetoelectric spin wave detector in the presence of thermal noise via compensation of demagnetization

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Sourav, E-mail: sdutta38@gatech.edu; Naeemi, Azad [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A. [Components Research, Intel Corporation, Hillsboro, Oregon 97124 (United States)

    2015-11-09

    The possibility of achieving phase-dependent deterministic switching of the magnetoelectric spin wave detector in the presence of thermal noise has been discussed. The proposed idea relies on the modification of the energy landscape by partially canceling the out-of-plane demagnetizing field and the resultant change in the intrinsic magnetization dynamics to drive the nanomagnet towards a preferential final magnetization state. The remarkable increase in the probability of successful switching can be accounted for by the shift in the location of the saddle point in the energy landscape and a resultant change in the nature of the relaxation dynamics of the magnetization from a highly precessional to a fairly damped one and an increased dependence on the initial magnetization values, a crucial requirement for phase-dependent spin wave detection.

  16. Proximity effects on the spin density waves in X/Cr(001) multilayers (X = Sn, V, and Mn)

    International Nuclear Information System (INIS)

    Amitouche, F.; Bouarab, S.; Tazibt, S.; Vega, A.; Demangeat, C.

    2011-01-01

    We present ab initio density functional calculations of the electronic structure and magnetic properties of X 2 /Cr 36 (001) and X 1 /Cr 37 (001) multilayers, with X = Sn, V and Mn, to investigate the impact of the proximity effects of the X layers on the spin density waves of the Cr slab. We find different magnetic profiles corresponding to the spin density wave and to the layered antiferromagnetic configurations. The nature of the different magnetic solutions is discussed in terms of the different interfacial environments in the proximity of Sn, V or Mn. The magnetic behavior at the interface is discussed in connection with the electronic structure through the density of electronic states projected at the interfacial X and Cr sites. We compare the results with those previously obtained for Fe 3 /X 1 /Cr 37 /X 1 (001) multilayers to analyze the role played by the ferromagnetic iron slab.

  17. Spin polarization driven by a charge-density wave in monolayer 1T−TaS2

    KAUST Repository

    Zhang, Qingyun; Gan, Liyong; Cheng, Yingchun; Schwingenschlö gl, Udo

    2014-01-01

    Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer T-phase TaS2. We demonstrate that a charge-density wave is energetically favorable at low temperature, similar to bulk 1T-TaS2. Electron-phonon coupling is found to be essential for the lattice reconstruction. The charge-density wave results in a strong localization of the electronic states near the Fermi level and consequently in spin polarization, transforming the material into a magnetic semiconductor with enhanced electronic correlations. The combination of inherent spin polarization with a semiconducting nature distinguishes the monolayer fundamentally from the bulk compound as well as from other two-dimensional transition metal dichalcogenides. Monolayer T-phase TaS2 therefore has the potential to enable two-dimensional spintronics. © 2014 American Physical Society.

  18. Superconductor to spin-density-wave transition in quasi-one-dimensional metals with repulsive anisotropic interaction

    International Nuclear Information System (INIS)

    Rozhkov, A.V.

    2007-01-01

    A mechanism for superconductivity in a quasi-one-dimensional system with repulsive Ising-anisotropic interaction is studied. The Ising anisotropy opens the gap Δ s in the spin sector of the model. This gap allows the triplet superconductivity and the spin-density wave as the only broken symmetry phases. These phases are separated by the first order transition. The transport properties of the system are investigated in different parts of the phase diagram. The calculation of DC conductivity σ(T) in the high-temperature phase shows that the function σ(T) cannot be used as an indicator of a superconducting ground state: even if σ(T) is a decreasing function at high temperature, yet, the ground state may be insulating spin-density wave; the opposite is also true. The calculation of the spin dynamical structure factor S zz (q, ω) demonstrates that it is affected by the superconducting phase transition in a qualitative fashion: below T c the structure factor develops a gap with a coherent excitation inside this gap

  19. Design of a 40-nm CMOS integrated on-chip oscilloscope for 5-50 GHz spin wave characterization

    Science.gov (United States)

    Egel, Eugen; Csaba, György; Dietz, Andreas; Breitkreutz-von Gamm, Stephan; Russer, Johannes; Russer, Peter; Kreupl, Franz; Becherer, Markus

    2018-05-01

    Spin wave (SW) devices are receiving growing attention in research as a strong candidate for low power applications in the beyond-CMOS era. All SW applications would require an efficient, low power, on-chip read-out circuitry. Thus, we provide a concept for an on-chip oscilloscope (OCO) allowing parallel detection of the SWs at different frequencies. The readout system is designed in 40-nm CMOS technology and is capable of SW device characterization. First, the SWs are picked up by near field loop antennas, placed below yttrium iron garnet (YIG) film, and amplified by a low noise amplifier (LNA). Second, a mixer down-converts the radio frequency (RF) signal of 5 - 50 GHz to lower intermediate frequencies (IF) around 10 - 50 MHz. Finally, the IF signal can be digitized and analyzed regarding the frequency, amplitude and phase variation of the SWs. The power consumption and chip area of the whole OCO are estimated to 166.4 mW and 1.31 mm2, respectively.

  20. Metal-ligand delocalization and spin density in the CuCl2 and [CuCl4](2-) molecules: Some insights from wave function theory.

    Science.gov (United States)

    Giner, Emmanuel; Angeli, Celestino

    2015-09-28

    The aim of this paper is to unravel the physical phenomena involved in the calculation of the spin density of the CuCl2 and [CuCl4](2-) systems using wave function methods. Various types of wave functions are used here, both variational and perturbative, to analyse the effects impacting the spin density. It is found that the spin density on the chlorine ligands strongly depends on the mixing between two types of valence bond structures. It is demonstrated that the main difficulties found in most of the previous studies based on wave function methods come from the fact that each valence bond structure requires a different set of molecular orbitals and that using a unique set of molecular orbitals in a variational procedure leads to the removal of one of them from the wave function. Starting from these results, a method to compute the spin density at a reasonable computational cost is proposed.

  1. Effect of Quark Spins to the Hadron Distributions for Chiral Magnetic Wave in Ultrarelativistic Heavy-Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Byungsik [Korea University, Seoul (Korea, Republic of)

    2017-07-15

    Topological fluctuation of the gluon field in quantum chromodynamics modifies the vacuum structure, and causes various chiral anomalies. In the strong magnetic field generated by semi-central heavy-ion collisions, the axial and vector density fluctuations propagate along the external magnetic field, called the chiral magnetic wave. Up to now the investigation of the various chiral anomalies in heavy ion collisions has been focussed on the charge distribution in the transverse plane. However, this paper points out that the information on the charge distribution is not enough and the spin effect should also be taken into account. Considering the charge and spin distributions together, π{sup ±} with spin 0 are not proper particle species to study the chiral anomalies, as the signal may be significantly suppressed as one of the constituent (anti)quarks should come from background to form the pseudoscalar states. It is, therefore, necessary to analyze explicitly the vector mesons with spin 1 (K⋆{sup ±} (892)) and baryons with spin 3/2 (Δ{sup ++}(1232), Σ{sup −} (1385) and Ω{sup −} ). If the chiral anomaly effects exist, the elliptic flow parameter is expected to be larger for negative particles for each particle species.

  2. Underwater Shock Wave Research Applied to Therapeutic Device Developments

    Science.gov (United States)

    Takayama, K.; Yamamoto, H.; Shimokawa, H.

    2013-07-01

    The chronological development of underwater shock wave research performed at the Shock Wave Research Center of the Institute of Fluid Science at the Tohoku University is presented. Firstly, the generation of planar underwater shock waves in shock tubes and their visualization by using the conventional shadowgraph and schlieren methods are described. Secondly, the generation of spherical underwater shock waves by exploding lead azide pellets weighing from several tens of micrograms to 100 mg, that were ignited by irradiating with a Q-switched laser beam, and their visualization by using double exposure holographic interferometry are presented. The initiation, propagation, reflection, focusing of underwater shock waves, and their interaction with various interfaces, in particular, with air bubbles, are visualized quantitatively. Based on such a fundamental underwater shock wave research, collaboration with the School of Medicine at the Tohoku University was started for developing a shock wave assisted therapeutic device, which was named an extracorporeal shock wave lithotripter (ESWL). Miniature shock waves created by irradiation with Q-switched HO:YAG laser beams are studied, as applied to damaged dysfunctional nerve cells in the myocardium in a precisely controlled manner, and are effectively used to design a catheter for treating arrhythmia.

  3. Research Centre for the Study of the Rogue Waves

    Science.gov (United States)

    Shamin, Roman

    2013-04-01

    In 2012, in Sakhalin (Russia) was established Research Center for the Study of the Rogue Waves. This center unites many known scientists, who study rogue waves. The center is founded by the following scientific organizations: - The Institute of Marine Geology and Geophysics of FEB RAS - The Far Eastern Federal University - Special Research Bureau for Automation of Marine Researches of FEB RAS - The Institute of Applied Physics of RAS - Shirshov Institute of Oceanology of RAS Heads this center Dr. Roman V. Shamin (Russia). Topics projects: - Probability of emergence of rogue waves - Finding of the sites of the Ocean most dangerous from the point of view of rogue waves - Assessment of risk of dangerous impact of rogue waves - and many others... Our Center is open for new participants from all countries. Our Centre have web-site: roguewaves.ru For contacts: center@roguewaves.ru (Dr. Roman Shamin)

  4. Experimental Research of a New Wave Energy Conversion Device

    Science.gov (United States)

    Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Chen, Gewei

    2018-01-01

    With the increasing tension of contemporary social energy, the development and utilization of renewable energy has become an important development direction. As an important part of renewable energy, wave energy has the characteristics of green environmental protection and abundant reserves, attracting more investment and research. For small marine equipment energy supply problem, this paper puts forward a micro wave energy conversion device as the basic of heaving motion of waves in the ocean. This paper designed a new type of power output device can solve the micro wave energy conversion problem.

  5. Illuminating "spin-polarized" Bloch wave-function projection from degenerate bands in decomposable centrosymmetric lattices

    Science.gov (United States)

    Li, Pengke; Appelbaum, Ian

    2018-03-01

    The combination of space inversion and time-reversal symmetries results in doubly degenerate Bloch states with opposite spin. Many lattices with these symmetries can be constructed by combining a noncentrosymmetric potential (lacking this degeneracy) with its inverted copy. Using simple models, we unravel the evolution of local spin splitting during this process of inversion symmetry restoration, in the presence of spin-orbit interaction and sublattice coupling. Importantly, through an analysis of quantum mechanical commutativity, we examine the difficulty of identifying states that are simultaneously spatially segregated and spin polarized. We also explain how surface-sensitive experimental probes (such as angle-resolved photoemission spectroscopy, or ARPES) of "hidden spin polarization" in layered materials are susceptible to unrelated spin splitting intrinsically induced by broken inversion symmetry at the surface.

  6. Interface boundary conditions for dynamic magnetization and spin wave dynamics in a ferromagnetic layer with the interface Dzyaloshinskii-Moriya interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kostylev, M. [School of Physics, M013, University of Western Australia, Crawley, Perth 6009, Western Australia (Australia)

    2014-06-21

    In this work, we derive the interface exchange boundary conditions for the classical linear dynamics of magnetization in ferromagnetic layers with the interface Dzyaloshinskii-Moriya interaction (IDMI). We show that IDMI leads to pinning of dynamic magnetization at the interface. An unusual peculiarity of the IDMI-based pinning is that its scales as the spin-wave wave number. We incorporate these boundary conditions into an existing numerical model for the dynamics of the Damon-Eshbach spin wave in ferromagnetic films. IDMI affects the dispersion and the frequency non-reciprocity of the travelling Damon-Eshbach spin wave. For a broad range of film thicknesses L and wave numbers, the results of the numerical simulations of the spin wave dispersion are in a good agreement with a simple analytical expression, which shows that the contribution of IDMI to the dispersion scales as 1/L, similarly to the effect of other types of interfacial anisotropy. Suggestions to experimentalists how to detect the presence of IDMI in a spin wave experiment are given.

  7. Localized spin-wave modes in a triangular magnetic element studied by micro-focused Brillouin light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, S.; Kwon, J.-H. [School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Grünberg, P. [Grünberg Center for Magnetic Nanomaterials, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Cho, B.K., E-mail: chobk@gist.ac.kr [School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of)

    2017-09-01

    Highlights: • Direct evidence of localized mode in a triangular nano-magnet using μ-BLS. • Localized regions are identified by the internal field distribution. • The spatially resolved measurement was performed to obtain 2-D intensity map. • Spin modes in same positions can be distinguish comparing with simulated spectrum. • Localized modes were identified by comparing with the simulated spatial profiles. - Abstract: Localized spin-wave modes, which were thermally excited at a specific position in a triangular magnetic element, were investigated using micro-focused Brillouin light scattering in two saturated states, the buckle and Y-states, with an applied magnetic field of 0.24 T parallel and perpendicular to the basal edge, respectively. The measured frequency spectrum at a specific beam spot position, rather than an integrated spectrum, was analyzed by comparing it with the simulation data at a precisely selected position within the beam spot area. The analyzed results were used to plot a two-dimensional intensity map and simulation spatial profile to verify the validity of the analysis. From the analysis process, two localized spin-wave modes in a triangular magnetic element were successfully identified near the apex region in the buckle state and near the basal edge region in the Y-state.

  8. Gravitational-wave research: Current status and future prospects

    International Nuclear Information System (INIS)

    Thorne, K.S.

    1980-01-01

    There is a reasonably good change that in the 1980s cosmic gravitational waves will be discovered and will become a powerful tool for astronomy. This prospect has stimulated a three-pronged research effort. First, relativity theorists are developing new mathematical tools for the analysis of gravitational radiation: including (i) methods of analyzing the generation of gravity waves by sources with strong self-gravity and large internal velocities (e.g., collisions of black holes), (ii) methods of computing radiation reaction in sources, and (iii) methods of analyzing how gravitational waves propagate through our lumpy curved-space Universe. Second, astrophysicists are attempting to identify the most promissing sources of gravitational waves, and are using the relativity theorists' mathematical tools to estimate the characteristics of the waves they emit. Third, with the estimated wave characteristics in mind, experimenters are designing and constructing a second generation of gravitational-wave detectors: detectors of three types: Doppler tracking of interplanetary spacecraft, Earth-based laser interferometers, and Earth-based Weber-type resonant bars. This article reviews, in brief, all three prongs of the research effort and gives references to more detailed articles about specialized aspects of gravitational-wave physics

  9. Giant titanium electron wave function in gallium oxide: A potential electron-nuclear spin system for quantum information processing

    Science.gov (United States)

    Mentink-Vigier, Frédéric; Binet, Laurent; Vignoles, Gerard; Gourier, Didier; Vezin, Hervé

    2010-11-01

    The hyperfine interactions of the unpaired electron with eight surrounding G69a and G71a nuclei in Ti-doped β-Ga2O3 were analyzed by electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopies. They are dominated by strong isotropic hyperfine couplings due to a direct Fermi contact interaction with Ga nuclei in octahedral sites of rutile-type chains oriented along b axis, revealing a large anisotropic spatial extension of the electron wave function. Titanium in β-Ga2O3 is thus best described as a diffuse (Ti4+-e-) pair rather than as a localized Ti3+ . Both electron and G69a nuclear spin Rabi oscillations could be observed by pulsed EPR and pulsed ENDOR, respectively. The electron spin decoherence time is about 1μs (at 4 K) and an upper bound of 520μs (at 8 K) is estimated for the nuclear decoherence time. Thus, β-Ga2O3:Ti appears to be a potential spin-bus system for quantum information processing with a large nuclear spin quantum register.

  10. Effect of external magnetic field on superconducting and spin density wave gaps of high-T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, B., E-mail: brunda@iopb.res.i [Govt. Science College, Malkangiri 764 048 (India); Raj, B.K. [B.J.B. College, Bhubaneswar 751 014 (India); Rout, G.C., E-mail: gcr@iopb.res.i [Condensed Matter Physics Group P.G. Dept. of Applied Physics and Ballistics, F.M. University, Balasore 756 019 (India)

    2009-07-01

    A theoretical model is addressed here to study the interplay of the superconductivity (SC) and the spin density wave (SDW) long range orders in underdoped region in the vicinity of on-set of superconductivity in presence of an external magnetic field. The order parameters are calculated by using Zubarev's technique of Green's functions and determined numerically self-consistently. The gap parameters are found to be strongly coupled to each other through their coupling constants. The interplay displays BCS type two gaps in the quasi-particle density of states (DOS) which resemble the tunneling conductance of STM experiments. The gap edges in the DOS appear at +-(z+z{sub 1}) and +-(z-z{sub 1}). The applied magnetic field further induces Zeeman splitting which is explained on the basis of spin-filter effect of tunneling experiment.

  11. Effect of external magnetic field on superconducting and spin density wave gaps of high-Tc superconductors

    International Nuclear Information System (INIS)

    Pradhan, B.; Raj, B.K.; Rout, G.C.

    2009-01-01

    A theoretical model is addressed here to study the interplay of the superconductivity (SC) and the spin density wave (SDW) long range orders in underdoped region in the vicinity of on-set of superconductivity in presence of an external magnetic field. The order parameters are calculated by using Zubarev's technique of Green's functions and determined numerically self-consistently. The gap parameters are found to be strongly coupled to each other through their coupling constants. The interplay displays BCS type two gaps in the quasi-particle density of states (DOS) which resemble the tunneling conductance of STM experiments. The gap edges in the DOS appear at ±(z+z 1 ) and ±(z-z 1 ). The applied magnetic field further induces Zeeman splitting which is explained on the basis of spin-filter effect of tunneling experiment.

  12. Switching of the Spin-Density-Wave in CeCoIn5 probed by Thermal Conductivity

    Science.gov (United States)

    Kim, Duk Y.; Lin, Shi-Zeng; Weickert, Franziska; Bauer, Eric D.; Ronning, Filip; Thompson, Joe D.; Movshovich, Roman

    Unconventional superconductor CeCoIn5 orders magnetically in a spin-density-wave (SDW) in the low-temperature and high-field corner of the superconducting phase. Recent neutron scattering experiment revealed that the single-domain SDW's ordering vector Q depends strongly on the direction of the magnetic field, switching sharply as the field is rotated through the anti-nodal direction. This switching may be manifestation of a pair-density-wave (PDW) p-wave order parameter, which develops in addition to the well-established d-wave order parameter due to the SDW formation. We have investigated the hypersensitivity of the magnetic domain with a thermal conductivity measurement. The heat current (J) was applied along the [110] direction such that the Q vector is either perpendicular or parallel to J, depending on the magnetic field direction. A discontinuous change of the thermal conductivity was observed when the magnetic field is rotated around the [100] direction within 0 . 2° . The thermal conductivity with the Q parallel to the heat current (J ∥Q) is approximately 15% lager than that with the Q perpendicular to the heat current (J ⊥Q). This result is consistent with additional gapping of the nodal quasiparticle by the p-wave PDW coupled to SDW. Work at Los Alamos was performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

  13. Proceedings of RIKEN BNL Research Center Workshop: Brookhaven Summer Program on Nucleon Spin Physics

    Energy Technology Data Exchange (ETDEWEB)

    Aschenauer, A.; Qiu, Jianwei; Vogelsang, W.; Yuan, F.

    2011-08-02

    Understanding the structure of the nucleon is of fundamental importance in sub-atomic physics. Already the experimental studies on the electro-magnetic form factors in the 1950s showed that the nucleon has a nontrivial internal structure, and the deep inelastic scattering experiments in the 1970s revealed the partonic substructure of the nucleon. Modern research focuses in particular on the spin and the gluonic structure of the nucleon. Experiments using deep inelastic scattering or polarized p-p collisions are carried out in the US at the CEBAF and RHIC facilities, respectively, and there are other experimental facilities around the world. More than twenty years ago, the European Muon Collaboration published their first experimental results on the proton spin structure as revealed in polarized deep inelastic lepton-nucleon scattering, and concluded that quarks contribute very little to the proton's spin. With additional experimental and theoretical investigations and progress in the following years, it is now established that, contrary to naive quark model expectations, quarks and anti-quarks carry only about 30% of the total spin of the proton. Twenty years later, the discovery from the polarized hadron collider at RHIC was equally surprising. For the phase space probed by existing RHIC experiments, gluons do not seem to contribute any to the proton's spin. To find out what carries the remaining part of proton's spin is a key focus in current hadronic physics and also a major driving force for the new generation of spin experiments at RHIC and Jefferson Lab and at a future Electron Ion Collider. It is therefore very important and timely to organize a series of annual spin physics meetings to summarize the status of proton spin physics, to focus the effort, and to layout the future perspectives. This summer program on 'Nucleon Spin Physics' held at Brookhaven National Laboratory (BNL) on July 14-27, 2010 [http://www.bnl.gov/spnsp/] is the

  14. Magnetic field influence on the spin-density wave of the organic conductor (TMTSF)2NO3

    International Nuclear Information System (INIS)

    Tomic, S.; Biskup, N.; Korin-Hamzic, B.; Basletic, M.; Hamzic, A.; Maki, K.; Fabre, J.M.; Bechgaard, K.

    1993-01-01

    We present the influence of a transverse magnetic field on the spin-density wave (SDW) ground state of the organic conductor (TMTSF) 2 NO 3 . Magnetic field increases the single-particle activation energy. A finite magnetic field (H C ) induces discontinuities in the magnetoresistance behaviour and its value is temperature dependent. The threshold electric field (E T ) for the SDW sliding increases in a magnetic field. All observed effects are strongly angle-dependent indicating that they are determined by the magnetic field component along the least-conduction (c * ) direction. We discuss these results in the framework of a theoretical model for the SDW with large imperfect nesting. (orig.)

  15. In-plane angular dependence of the spin-wave nonreciprocity of an ultrathin film with Dzyaloshinskii-Moriya interaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Vanessa Li; Di, Kai; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau, E-mail: phykmh@nus.edu.sg [Department of Physics, National University of Singapore, Singapore 117551 (Singapore); Yu, Jiawei; Yoon, Jungbum; Qiu, Xuepeng; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-07-13

    The nonreciprocal propagation of spin waves in an ultrathin Pt/Co/Ni film has been measured by Brillouin light scattering. The frequency nonreciprocity, due to the interfacial Dzyaloshinskii-Moriya interaction (DMI), has a sinusoidal dependence on the in-plane angle between the magnon wavevector and the applied magnetic field. The results, which are in good agreement with analytical predictions reported earlier, yield a value of the DMI constant which is the same as that obtained previously from a study of the magnon dispersion relations. We have demonstrated that our magnon-dynamics based method can experimentally ascertain the DMI constant of multilayer thin films.

  16. Polarized-neutron-scattering study of the spin-wave excitations in the 3-k ordered phase of uranium antimonide.

    Science.gov (United States)

    Magnani, N; Caciuffo, R; Lander, G H; Hiess, A; Regnault, L-P

    2010-03-24

    The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.

  17. Making waves | IDRC - International Development Research Centre

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-01-26

    Jan 26, 2011 ... However, in 1990 there were no models for how information and ... Computers, the Internet, mobile phones, interactive CD-ROMs, newspapers, the radio ... The research: Creative technological fixes and social innovations.

  18. Wave-current interactions at the FloWave Ocean Energy Research Facility

    Science.gov (United States)

    Noble, Donald; Davey, Thomas; Steynor, Jeffrey; Bruce, Tom; Smith, Helen; Kaklis, Panagiotis

    2015-04-01

    Physical scale model testing is an important part of the marine renewable energy development process, allowing the study of forces and device behaviour in a controlled environment prior to deployment at sea. FloWave is a new state-of-the-art ocean energy research facility, designed to provide large scale physical modelling services to the tidal and wave sector. It has the unique ability to provide complex multi-directional waves that can be combined with currents from any direction in the 25m diameter circular tank. The facility is optimised for waves around 2s period and 0.4m height, and is capable of generating currents upwards of 1.6m/s. This offers the ability to model metocean conditions suitable for most renewable energy devices at a typical scale of between 1:10 and 1:40. The test section is 2m deep, which can be classed as intermediate-depth for most waves of interest, thus the full dispersion equation must be solved as the asymptotic simplifications do not apply. The interaction between waves and currents has been studied in the tank. This has involved producing in the tank sets of regular waves, focussed wave groups, and random sea spectra including multi-directional sea states. These waves have been both inline-with and opposing the current, as well as investigating waves at arbitrary angles to the current. Changes in wave height and wavelength have been measured, and compared with theoretical results. Using theoretical wave-current interaction models, methods have been explored to "correct" the wave height in the central test area of the tank when combined with a steady current. This allows the wave height with current to be set equal to that without a current. Thus permitting, for example, direct comparison of device motion response between tests with and without current. Alternatively, this would also permit a specific wave height and current combination to be produced in the tank, reproducing recorded conditions at a particular site of interest. The

  19. Kinetic analysis of spin current contribution to spectrum of electromagnetic waves in spin-1/2 plasma. I. Dielectric permeability tensor for magnetized plasmas

    Science.gov (United States)

    Andreev, Pavel A.

    2017-02-01

    The dielectric permeability tensor for spin polarized plasmas is derived in terms of the spin-1/2 quantum kinetic model in six-dimensional phase space. Expressions for the distribution function and spin distribution function are derived in linear approximations on the path of dielectric permeability tensor derivation. The dielectric permeability tensor is derived for the spin-polarized degenerate electron gas. It is also discussed at the finite temperature regime, where the equilibrium distribution function is presented by the spin-polarized Fermi-Dirac distribution. Consideration of the spin-polarized equilibrium states opens possibilities for the kinetic modeling of the thermal spin current contribution in the plasma dynamics.

  20. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  1. A two-component wave equation for particles of spin 1/2 and non-zero rest mass

    International Nuclear Information System (INIS)

    Srivastava, T.

    1981-11-01

    We have discussed here the qualifications of the equation (delta 0 +sigmasup(k)deltasub(k))psi = -kappaTpsi, where deltasub(μ) is identical to delta/deltaxsup(μ), sigmasup(k) are the Pauli spin matrices, T is the linear operator which changes the sign of t, kappa=m 0 c/(h/2π) and psi a function with two components, as a suitable wave equation for a spin 1/2 particle with non-zero rest mass. We have established that both components of all its solutions satisfy the Klein-Gordon equation and that a 1-1 correspondence can be set up between its solutions and the positive energy solutions of the Dirac equation which preserves inner products (suitably defined for our case). We have then gone on to show covariance under transformations of the proper Lorentz group as also under space and time inversions and translations. Eigenfunctions of energy-momentum and spin have been explicitly found and it is shown that causality is preserved and a Green's function exists. A list appears, at the end, of points to be discussed in Part II of this paper, points which, it is hoped, will complete the acceptability of the theory. (author)

  2. Electromagnetic waves for thermonuclear fusion research

    CERN Document Server

    Mazzucato, Ernesto

    2014-01-01

    The science of magnetically confined plasmas covers the entire spectrum of physics from classical and relativistic electrodynamics to quantum mechanics. During the last sixty years of research, our initial primitive understanding of plasma physics has made impressive progress thanks to a variety of experiments - from tabletop devices with plasma temperatures of a few thousands of degrees and confinement times of less than 100 microseconds, to large tokamaks with plasma temperatures of up to five hundred million degrees and confinement times approaching one second. We discovered that plasma con

  3. Proximity effects on the spin density waves in X/Cr(001) multilayers (X = Sn, V, and Mn)

    Energy Technology Data Exchange (ETDEWEB)

    Amitouche, F. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Bouarab, S., E-mail: bouarab_said@mail.ummto.d [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Tazibt, S. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Vega, A. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Prado de la Magdalena s/n, E-47011 Valladolid (Spain); Demangeat, C. [Institut de Physique, 3 rue de l' Universite 67000 Strasbourg (France)

    2011-01-03

    We present ab initio density functional calculations of the electronic structure and magnetic properties of X{sub 2}/Cr{sub 36}(001) and X{sub 1}/Cr{sub 37}(001) multilayers, with X = Sn, V and Mn, to investigate the impact of the proximity effects of the X layers on the spin density waves of the Cr slab. We find different magnetic profiles corresponding to the spin density wave and to the layered antiferromagnetic configurations. The nature of the different magnetic solutions is discussed in terms of the different interfacial environments in the proximity of Sn, V or Mn. The magnetic behavior at the interface is discussed in connection with the electronic structure through the density of electronic states projected at the interfacial X and Cr sites. We compare the results with those previously obtained for Fe{sub 3}/X{sub 1}/Cr{sub 37}/X{sub 1}(001) multilayers to analyze the role played by the ferromagnetic iron slab.

  4. 1H NMR studies in the regime of the field-induced spin-density wave phases of (TMTSF)2PF6

    International Nuclear Information System (INIS)

    Brown, S.E.; Pieper, M.; Clark, W.G.; Chow, D.S.; Alavi, B.

    1999-01-01

    We report 1 H proton spin-lattice relaxation measurements T 1 -1 on pressurized (TMTSF) 2 PF 6 in high magnetic fields. Maxima in T 1 -1 identify the phase transition to the field-induced spin-density wave (FISDW) state. Fluctuation effects are evident at temperatures above the transition, and vanish continuously in strength as the field is lowered to the critical field B c for the onset of the FISDW cascade. (orig.)

  5. Standing spin-wave mode structure and linewidth in partially disordered hexagonal arrays of perpendicularly magnetized sub-micron Permalloy discs

    International Nuclear Information System (INIS)

    Ross, N.; Kostylev, M.; Stamps, R. L.

    2014-01-01

    Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.

  6. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    International Nuclear Information System (INIS)

    Andreev, Pavel A.

    2015-01-01

    We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction

  7. Modified spin-wave theory with ordering vector optimization: frustrated bosons on the spatially anisotropic triangular lattice

    Energy Technology Data Exchange (ETDEWEB)

    Hauke, Philipp [ICFO-Institut de Ciencies Fotoniques, Meditarranean Technology Park, E-08860 Castelldefels, Barcelona (Spain); Roscilde, Tommaso [Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46 Allee d' Italie, F-69007 Lyon (France); Murg, Valentin; Ignacio Cirac, J; Schmied, Roman, E-mail: Philipp.Hauke@icfo.e [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)

    2010-05-15

    We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular, we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a one-dimensional (1D) quasi-ordered phase, a 2D Neel ordered phase and a 2D spiraling ordered phase. Strong indications coming from the ED and PEPS calculations, as well as from the breakdown of MSW theory, suggest that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory, we also explore the finite-temperature phase diagram. In agreement with the Berezinskii-Kosterlitz-Thouless (BKT) theory, we find that zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a BKT transition temperature), while zero-temperature quasi-ordered phases become short-range correlated at finite temperature. These results show that, despite its simplicity, MSW theory is very well suited to describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast and reliable method for singling out Hamiltonians that may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator

  8. Research activities and plan of electron cyclotron wave startup and Alfven wave current drive at SUNIST

    International Nuclear Information System (INIS)

    Gao Zhe; He Yexi; Tan Yi

    2009-01-01

    Using electromagnetic waves to startup and sustain plasma current takes a important role in the research program of the SUNIST spherical tokamak. Electron cyclotron ware (ECW) current startup have been investigated and revealed two totally different regimes. In the regime of very low working pressure, a plasma current of about 2 kA is obtained with a steadily applied vertical field of 12 Gauss and 40 kW/2.45 GHz microwave injection. In addition, the physics of the transient process during ECW startup in the relatively high working pressure regime is analyzed. The hardware preparation for the experimental research of Alfven wave current drive is being performed. The Alfven wave antenna system consists of four models in toroidal direction and two antenna straps in poloidal direction for each module and the rf generator has been designed as a four-phase oscillator (4x100 kW, 0.5 - 1 Mhz).The impedance spectrum of the antenna system is roughly evaluated by 1-D cylindrical magneto-hydrodynamic calculation. To investigate the wave-plasma interaction in ECW startup and Alfven wave current drive, upgrade of the device, especially in equilibrium control and diagnostics, is ongoing. (author)

  9. Estimation of spin contamination error in dissociative adsorption of Au2 onto MgO(0 0 1) surface: First application of approximate spin projection (AP) method to plane wave basis

    Science.gov (United States)

    Tada, Kohei; Koga, Hiroaki; Okumura, Mitsutaka; Tanaka, Shingo

    2018-06-01

    Spin contamination error in the total energy of the Au2/MgO system was estimated using the density functional theory/plane-wave scheme and approximate spin projection methods. This is the first investigation in which the errors in chemical phenomena on a periodic surface are estimated. The spin contamination error of the system was 0.06 eV. This value is smaller than that of the dissociation of Au2 in the gas phase (0.10 eV). This is because of the destabilization of the singlet spin state due to the weakening of the Au-Au interaction caused by the Au-MgO interaction.

  10. Spin-off from Research Exhibition Science Bringing Nations Together

    CERN Multimedia

    2000-01-01

    The purpose of fundamental research in physics is to discover the laws of Nature. The results of this research become available to all mankind, allowing breakthroughs in high technology and in the development of human civilization. Modern physics makes a decisive contribution to such highly important areas as cancer treatment, medical applications of nuclear detectors, computer tomography, World Wide Web, safe nuclear power, and many others.

  11. Research on a new wave energy absorption device

    Science.gov (United States)

    Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Zhu, Yiming

    2018-01-01

    To reduce impact of global warming and the energy crisis problems caused by pollution of energy combustion, the research on renewable and clean energies becomes more and more important. This paper designed a new wave absorption device, and also gave an introduction on its mechanical structure. The flow tube model is analyzed, and presented the formulation of the proposed method. To verify the principle of wave absorbing device, an experiment was carried out in a laboratory environment, and the results of the experiment can be applied for optimizing the structure design of output power.

  12. Propagation of magnetostatic spin waves in an yttrium iron garnet film for out-of-plane magnetic fields

    Science.gov (United States)

    Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Ketterson, John B.

    2018-06-01

    We have observed the propagation of spin waves across a thin yttrium iron garnet film on (1 1 1) gadolinium gallium garnet for magnetic fields inclined with respect to the film plane. Two principle planes were studied: that for H in the plane defined by the wave vector k and the plane normal, n, with limiting forms corresponding to the Backward Volume and Forward Volume modes, and that for H in the plane perpendicular to k, with limiting forms corresponding to the Damon-Eshbach and Forward Volume modes. By exciting the wave at one edge of the film and observing the field dependence of the phase of the received signal at the opposing edge we determined the frequency vs. wavevector relation, ω = ω (k), of various propagating modes in the film. Avoided crossings are observed in the Damon-Eshbach and Forward Volume regimes when the propagating mode intersects the higher, exchange split, volume modes, leading to an extinction of the propagating mode; analysis of the resulting behavior allows a determination of the exchange parameter. The experimental results are compared with theoretical simulations.

  13. Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Kjær, Kasper Skov; Hartsock, Robert

    2017-01-01

    The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation...... is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic...

  14. Path integral for spinning particle in the plane wave field: Global and local projections

    International Nuclear Information System (INIS)

    Boudiaf, N.; Boudjedaa, T.; Chetouani, L.

    2001-01-01

    The Green function related to the problem of a Dirac particle interacting with a plane wave is calculated via the path integral formalism proposed recently by Alexandrou et al. according to the two so-called global and local projections. With the help of the incorporation of two simple identities, it is shown that the contribution to the calculation of the integrals comes essentially from classical solutions projected along the direction of wave propagation. (orig.)

  15. High-spin research with HERA [High Energy-Resolution Array

    International Nuclear Information System (INIS)

    Diamond, R.M.

    1987-06-01

    The topic of this report is high spin research with the High Energy Resolution Array (HERA) at Lawrence Berkeley Laboratory. This is a 21 Ge detector system, the first with bismuth germanate (BGO) Compton suppression. The array is described briefly and some of the results obtained during the past year using this detector facility are discussed. Two types of studies are described: observation of superdeformation in the light Nd isotopes, and rotational damping at high spin and excitation energy in the continuum gamma ray spectrum

  16. Electron-spin-resonance techniques in fuel research

    Energy Technology Data Exchange (ETDEWEB)

    1965-06-01

    E.s.r. techniques provide a sensitive means of identifying the free radicals present in pyrolytic and combustion reactions, and determining their concentration. This article explains the theoretical basis of these techniques and indicates the scope of the work recently initiated with the e.s.r. spectrometer at the Division of Coal Research.

  17. Leadership in applied psychology: Three waves of theory and research.

    Science.gov (United States)

    Lord, Robert G; Day, David V; Zaccaro, Stephen J; Avolio, Bruce J; Eagly, Alice H

    2017-03-01

    Although in the early years of the Journal leadership research was rare and focused primarily on traits differentiating leaders from nonleaders, subsequent to World War II the research area developed in 3 major waves of conceptual, empirical, and methodological advances: (a) behavioral and attitude research; (b) behavioral, social-cognitive, and contingency research; and (c) transformational, social exchange, team, and gender-related research. Our review of this work shows dramatic increases in sophistication from early research focusing on personnel issues associated with World War I to contemporary multilevel models and meta-analyses on teams, shared leadership, leader-member exchange, gender, ethical, abusive, charismatic, and transformational leadership. Yet, many of the themes that characterize contemporary leadership research were also present in earlier research. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. Commercial Scholarship: Spinning Physics Research into a Business Enterprise

    Science.gov (United States)

    Butler, Orville

    2013-03-01

    The American Institute of Physics' Center for History of Physics has conducted a three year NSF funded study of physicist entrepreneurs during which we interviewed 140 physicists who have founded ninety-one startups. Forty of those companies have spun research out of twenty-some universities. Startups spun out of university research tend to be technology push companies, creating new potentially disruptive technologies for which markets do not yet clearly exist, in contrast to market pull companies founded to address innovations responding to market demands. This paper addresses the unique issues found in university spinout companies and their responses to them. While technology push companies are generally considered to be higher risk compared to market pull companies, the university spinouts in our study had a higher rate of both SBIR and venture capital funding than did the market pull companies in our study.

  19. Spin-Off Successes of SETI Research at Berkeley

    Science.gov (United States)

    Douglas, K. A.; Anderson, D. P.; Bankay, R.; Chen, H.; Cobb, J.; Korpela, E. J.; Lebofsky, M.; Parsons, A.; von Korff, J.; Werthimer, D.

    2009-12-01

    Our group contributes to the Search for Extra-Terrestrial Intelligence (SETI) by developing and using world-class signal processing computers to analyze data collected on the Arecibo telescope. Although no patterned signal of extra-terrestrial origin has yet been detected, and the immediate prospects for making such a detection are highly uncertain, the SETI@home project has nonetheless proven the value of pursuing such research through its impact on the fields of distributed computing, real-time signal processing, and radio astronomy. The SETI@home project has spun off the Center for Astronomy Signal Processing and Electronics Research (CASPER) and the Berkeley Open Infrastructure for Networked Computing (BOINC), both of which are responsible for catalyzing a smorgasbord of new research in scientific disciplines in countries around the world. Futhermore, the data collected and archived for the SETI@home project is proving valuable in data-mining experiments for mapping neutral galatic hydrogen and for detecting black-hole evaporation.

  20. A temperature dependent tunneling study of the spin density wave gap in EuFe2As2 single crystals.

    Science.gov (United States)

    Dutta, Anirban; Anupam; Hossain, Z; Gupta, Anjan K

    2013-09-18

    We report temperature dependent scanning tunneling microscopy and spectroscopy measurements on single crystals of EuFe2As2 in the 15-292 K temperature range. The in situ cleaved crystals show atomic terraces with homogeneous tunnel spectra that correlate well with the spin density wave (SDW) transition at a temperature, TSDW ≈ 186 K. Above TSDW the local tunnel spectra show a small depression in the density of states (DOS) near the Fermi energy (EF). The gap becomes more pronounced upon entering the SDW state with a gap value ∼90 meV at 15 K. However, the zero bias conductance remains finite down to 15 K indicating a finite DOS at the EF in the SDW phase. Furthermore, no noticeable change is observed in the DOS at the antiferromagnetic ordering transition of Eu(2+) moments at 19 K.

  1. Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited

    Directory of Open Access Journals (Sweden)

    Necdet Onur Urs

    2016-05-01

    Full Text Available Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown.

  2. Sensitivity of new detection method for ultra-low frequency gravitational waves with pulsar spin-down rate statistics

    Science.gov (United States)

    Yonemaru, Naoyuki; Kumamoto, Hiroki; Takahashi, Keitaro; Kuroyanagi, Sachiko

    2018-04-01

    A new detection method for ultra-low frequency gravitational waves (GWs) with a frequency much lower than the observational range of pulsar timing arrays (PTAs) was suggested in Yonemaru et al. (2016). In the PTA analysis, ultra-low frequency GWs (≲ 10-10 Hz) which evolve just linearly during the observation time span are absorbed by the pulsar spin-down rates since both have the same effect on the pulse arrival time. Therefore, such GWs cannot be detected by the conventional method of PTAs. However, the bias on the observed spin-down rates depends on relative direction of a pulsar and GW source and shows a quadrupole pattern in the sky. Thus, if we divide the pulsars according to the position in the sky and see the difference in the statistics of the spin-down rates, ultra-low frequency GWs from a single source can be detected. In this paper, we evaluate the potential of this method by Monte-Carlo simulations and estimate the sensitivity, considering only the "Earth term" while the "pulsar term" acts like random noise for GW frequencies 10-13 - 10-10 Hz. We find that with 3,000 milli-second pulsars, which are expected to be discovered by a future survey with the Square Kilometre Array, GWs with the derivative of amplitude of about 3 × 10^{-19} {s}^{-1} can in principle be detected. Implications for possible supermassive binary black holes in Sgr* and M87 are also given.

  3. Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

    Science.gov (United States)

    Epel, Boris; Sundramoorthy, Subramanian V.; Barth, Eugene D.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above∼100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors. PMID:21626937

  4. p -wave superconductivity in weakly repulsive 2D Hubbard model with Zeeman splitting and weak Rashba spin-orbit coupling

    Science.gov (United States)

    Hugdal, Henning G.; Sudbø, Asle

    2018-01-01

    We study the superconducting order in a two-dimensional square lattice Hubbard model with weak repulsive interactions, subject to a Zeeman field and weak Rashba spin-orbit interactions. Diagonalizing the noninteracting Hamiltonian leads to two separate bands, and by deriving an effective low-energy interaction we find the mean field gap equations for the superconducting order parameter on the bands. Solving the gap equations just below the critical temperature, we find that superconductivity is caused by Kohn-Luttinger-type interaction, while the pairing symmetry of the bands is indirectly affected by the spin-orbit coupling. The dominating attractive momentum channel of the Kohn-Luttinger term depends on the filling fraction n of the system, and it is therefore possible to change the momentum dependence of the order parameter by tuning n . Moreover, n also determines which band has the highest critical temperature. Rotating the magnetic field changes the momentum dependence from states that for small momenta reduce to a chiral px±i py type state for out-of-plane fields, to a nodal p -wave-type state for purely in-plane fields.

  5. SimLabel: a graphical user interface to simulate continuous wave EPR spectra from site-directed spin labeling experiments.

    Science.gov (United States)

    Etienne, E; Le Breton, N; Martinho, M; Mileo, E; Belle, V

    2017-08-01

    Site-directed spin labeling (SDSL) combined with continuous wave electron paramagnetic resonance (cw EPR) spectroscopy is a powerful technique to reveal, at the residue level, structural transitions in proteins. SDSL-EPR is based on the selective grafting of a paramagnetic label on the protein under study, followed by cw EPR analysis. To extract valuable quantitative information from SDSL-EPR spectra and thus give reliable interpretation on biological system dynamics, numerical simulations of the spectra are required. Such spectral simulations can be carried out by coding in MATLAB using functions from the EasySpin toolbox. For non-expert users of MATLAB, this could be a complex task or even impede the use of such simulation tool. We developed a graphical user interface called SimLabel dedicated to run cw EPR spectra simulations particularly coming from SDSL-EPR experiments. Simlabel provides an intuitive way to visualize, simulate, and fit such cw EPR spectra. An example of SDSL-EPR spectra simulation concerning the study of an intrinsically disordered region undergoing a local induced folding is described and discussed. We believe that this new tool will help the users to rapidly obtain reliable simulated spectra and hence facilitate the interpretation of their results. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  6. X-ray detected magnetic resonance of YIG thin films in the nonlinear regime of spin waves

    Energy Technology Data Exchange (ETDEWEB)

    Goulon, J., E-mail: goulon@esrf.f [European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex (France); Rogalev, A.; Wilhelm, F.; Goujon, G. [European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex (France); Brouder, Ch. [Institut de Mineralogie et de Physique des Milieux Condenses, UMR-CNRS 7590, Universite Paris VI-VII, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Yaresko, A. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Ben Youssef, J.; Indenbom, M.V. [Laboratoire de Magnetisme de Bretagne, CNRS FRE 2697, UFR Sciences et Techniques, F-29328 Brest Cedex (France)

    2010-08-15

    We discuss the information content of element/edge resolved X-ray detected magnetic resonance (XDMR) experiments carried out on yttrium iron garnet (YIG) thin films. Starting with a phenomenological approach, it is shown that the photoionisation of deep atomic core levels by circularly polarized X-rays can be used to probe the precession dynamics of spin or orbital magnetization components in empty final states of proper symmetry. Crude estimates of the opening angle of the uniform precession mode were tentatively deduced from the ratio of the XDMR and XMCD absorption cross-sections either at the iron or yttrium absorbing sites. The implications of the most recent experimental results collected at the ESRF are analyzed, keeping in mind that: (i) the Fe K-edge XDMR signal is largely dominated by the precession of orbital magnetization components at the tetrahedral iron sites; (ii) the Y L-edges XDMR signal essentially describes the precession of induced spin magnetization involving the 4d states of yttrium. In the magnetostatic regime, we produce clear experimental evidence of collective excitations of orbital magnetization waves, especially under high pumping power. Several coupling mechanisms could explain our observations, starting with pseudo-dipolar interactions in ferromagnetic systems. In ferrimagnetic systems in which orbital degeneracy and orbital ordering make the excitation of orbitons possible, one may envisage additional modes of excitation or relaxation of orbital magnetization waves. This interpretation looks fully consistent with the results of band structure calculations carried out recently on YIG with fully relativistic LMTO-LSDA methods.

  7. 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 ...

  8. Low-frequency permittivity of spin-density wave in (TMTSF)2PF6 at low temperatures

    DEFF Research Database (Denmark)

    Nad, F.; Monceau, P.; Bechgaard, K.

    1995-01-01

    Conductivity and permittivity epsilon of(TMTSF)(2)PF6 have been measured at low frequencies of (10(2)-10(7) Hz) at low temperatures below the spin-density wave (SDW) transition temperature T-p. The temperature dependence of the conductivity shows a deviation from thermally activated behavior at T...

  9. Nurture or nature? The growth paradox of research-based spin-offs

    OpenAIRE

    Zerbinati, S.; Souitaris, V.; Moray, N.

    2012-01-01

    This study explores the effect of institutional origin (‘nurture’) and economic context (‘nature’) on the financial resource endowment and subsequent early employment growth of research-based spin-offs (RBSOs). The nurture dimensions capture the relationship between the parent research institution and the RBSO during the start-up phase: the type of incubation model, the formal vs informal transfer of technology and the extent of inventors’ involvement with the firm. The nature dimensions incl...

  10. Spin-offs from Research Exhibition Science Bringing Nations Together

    CERN Multimedia

    1997-01-01

    It is well known that the results of fundamental research can have unexpected and suc-cessful applications in different fields of human activity. A good example is that of nuclear track membranes. These membranes are produced by exposing polymer films to ion beams at isochronous cyclotrons in JINR. They are used in all fields that require reliable and ecologically safe filters; e.g. in medicine and in the food and elec-tronics industries. It is not surprising that Finnish businessmen readily accepted the proposal of the specialists from JINR's Laboratory of Nuclear Reactions to establish a joint venture for production of household water filters, and that these simple but effective devices are now used in many countries.

  11. Strongly gapped spin-wave excitation in the insulating phase of NaOsO3

    International Nuclear Information System (INIS)

    Calder, S.; Vale, J. G.; Bogdanov, N.; Donnerer, C.

    2017-01-01

    NaOsO_3 hosts a rare manifestation of a metal-insulator transition driven by magnetic correlations, placing the magnetic exchange interactions in a central role. We use resonant inelastic x-ray scattering to directly probe these magnetic exchange interactions. A dispersive and strongly gapped (58 meV) excitation is observed indicating appreciable spin-orbit coupling in this 5d"3 system. The excitation is well described within a minimal model Hamiltonian with strong anisotropy and Heisenberg exchange (J_1 = J_2 = 13.9 meV). As a result, the observed behavior places NaOsO_3 on the boundary between localized and itinerant magnetism.

  12. Massive-spin-1/2 wave around a Kerr-Newman black hole

    International Nuclear Information System (INIS)

    Lee, C.H.

    1977-01-01

    Using the separation of variables of the Dirac equations for the electron in the Kerr-Newman geometry, it is explicitly shown that the super-radiant scattering is not allowed for the electron wave on a Kerr-Newman black hole

  13. Experimental research on crossing shock wave boundary layer interactions

    Science.gov (United States)

    Settles, G. S.; Garrison, T. J.

    1994-10-01

    An experimental research effort of the Penn State Gas Dynamics Laboratory on the subject of crossing shock wave boundary layer interactions is reported. This three year study was supported by AFOSR Grant 89-0315. A variety of experimental techniques were employed to study the above phenomena including planar laser scattering flowfield visualization, kerosene lampblack surface flow visualization, laser-interferometer skin friction surveys, wall static pressure measurements, and flowfield five-hole probe surveys. For a model configuration producing two intersecting shock waves, measurements were made for a range of oblique shock strengths at freestream Mach numbers of 3.0 and 3.85. Additionally, measurements were made at Mach 3.85 for a configuration producing three intersecting waves. The combined experimental dataset was used to formulate the first detailed flowfield models of the crossing-shock and triple-shock wave/boundary layer interactions. The structure of these interactions was found to be similar over a broad range of interaction strengths and is dominated by a large, separated, viscous flow region.

  14. Pressure effects on spin density wave in Cr rich Cr-Al, Si, Mn, Fe and Co alloys

    International Nuclear Information System (INIS)

    Mizuki, Jun-ichiro; Endoh, Yasuo; Ishikawa, Yoshikazu

    1982-01-01

    The effect of pressure on the spin density wave (SDW) state in Cr rich Cr-Al, Si, Nn, Fe and Co alloys has been elucidated by neutron diffraction studies. We found that the change of the SDW wave vector Q, by applying pressure, 1/Q. delta Q/ delta P, is linearly related to the decrease of T sub(N) with increasing pressure 1/T sub(N). delta T sub(N)/ delta P and that all the results from the Cr-Si, Fe and Co alloys fall on a single straight line independent of their concentrations. Their magnetic phase diagrams in a temperature-pressure coordinate system can be related to the alloy phase diagram by employing an empirical rule that applying pressure corresponds to a decrese in the electron to atom ratio. The non transition metal Si impurity has been found to act as an electron donor, while the effect of Al is not interpreted by the two band nesting model. (author)

  15. The impact of wave number selection and spin up time when using spectral nudging for dynamical downscaling applications

    Science.gov (United States)

    Gómez, Breogán; Miguez-Macho, Gonzalo

    2017-04-01

    Nudging techniques are commonly used to constrain the evolution of numerical models to a reference dataset that is typically of a lower resolution. The nudged model retains some of the features of the reference field while incorporating its own dynamics to the solution. These characteristics have made nudging very popular in dynamic downscaling applications that cover from shot range, single case studies, to multi-decadal regional climate simulations. Recently, a variation of this approach called Spectral Nudging, has gained popularity for its ability to maintain the higher temporal and spatial variability of the model results, while forcing the large scales in the solution with a coarser resolution field. In this work, we focus on a not much explored aspect of this technique: the impact of selecting different cut-off wave numbers and spin-up times. We perform four-day long simulations with the WRF model, daily for three different one-month periods that include a free run and several Spectral Nudging experiments with cut-off wave numbers ranging from the smallest to the largest possible (full Grid Nudging). Results show that Spectral Nudging is very effective at imposing the selected scales onto the solution, while allowing the limited area model to incorporate finer scale features. The model error diminishes rapidly as the nudging expands over broader parts of the spectrum, but this decreasing trend ceases sharply at cut-off wave numbers equivalent to a length scale of about 1000 km, and the error magnitude changes minimally thereafter. This scale corresponds to the Rossby Radius of deformation, separating synoptic from convective scales in the flow. When nudging above this value is applied, a shifting of the synoptic patterns can occur in the solution, yielding large model errors. However, when selecting smaller scales, the fine scale contribution of the model is damped, thus making 1000 km the appropriate scale threshold to nudge in order to balance both effects

  16. Advanced accelerator and mm-wave structure research at LANL

    Energy Technology Data Exchange (ETDEWEB)

    Simakov, Evgenya Ivanovna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-22

    This document outlines acceleration projects and mm-wave structure research performed at LANL. The motivation for PBG research is described first, with reference to couplers for superconducting accelerators and structures for room-temperature accelerators and W-band TWTs. These topics are then taken up in greater detail: PBG structures and the MIT PBG accelerator; SRF PBG cavities at LANL; X-band PBG cavities at LANL; and W-band PBG TWT at LANL. The presentation concludes by describing other advanced accelerator projects: beam shaping with an Emittance Exchanger, diamond field emitter array cathodes, and additive manufacturing of novel accelerator structures.

  17. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP CIRCUM-PAN-PACIFIC RIKEN SYMPOSIUM ON HIGH ENERGY SPIN PHYSICS, VOLUME 25

    Energy Technology Data Exchange (ETDEWEB)

    KUMANO,S.; SHIBATA,T.A.; YAZAKI,K.

    2000-06-28

    The Circum-Pan-Pacific Riken Symposium on High Energy Spin Physics was held at Oukouchi Memorial Hall in Riken from November 3 through 6, 1999. It was held as a joint meeting of the 2nd Circum-Pan-Pacific Symposium on High Energy Spin Physics and the 3rd of the series of Riken Symposia related to the RHIC-SPIN. The 1st Circum-Pan-Pacific Symposium on High Energy Spin Physics was held at Kobe in 1996 and the RHIC-SPIN Riken Symposia had been held every two years since 1995. As Prof. Ozaki mentioned in his talk at the beginning of this meeting, the RHIC was ready for the first beam, physics experiments scheduled in 2000, and the RHIC-SPIN would start in 2001. It was therefore considered to be very timely for the researchers in the field of high energy spin physics to get together, clarifying the present status of the field and discussing interesting and important topics as well as experimental subjects to be pursued. It is especially important for the success of the RHIC-SPIN project that the researchers in the neighboring countries surrounding the Pacific are actively involved in it. This is why the above two series were joined in this. symposium. The subjects discussed in the symposium include: Hard processes probing spin-structure functions, polarization mechanisms in high energy reactions, lattice studies of polarized structure functions, theoretical models for the nucleon and its spin structure, RHIC and RHIC-SPIN projects, results and future projects of existing experimental facilities. Totally 73 scientists participated in the symposium, 27 from abroad and 46 from Japan. it consisted of 13 main sessions, with 33 invited and contributed talks, and 4 discussion sessions covering recent experimental and theoretical developments and important topics in high energy spin physics and closely related fields.

  18. Locational conditions, cooperation, and innovativeness: evidence from research and company spin-offs

    OpenAIRE

    Lejpras, Anna; Stephan, Andreas

    2008-01-01

    This paper has two goals. First, it analyzes the extent to which the innovativeness of spin-offs, either born from a research facility or from another company, is influenced by locational conditions. Second, it provides evidence on how important local cooperation links are in comparison to nonlocal ones. Using a sample of approximately 1,500 East German firms from knowledge-intensive sectors, we estimate a structural equation model applying the partial least squares method. We find that proxi...

  19. The Bloch self-consistently renormalized spin wave approximation and behaviour of some thermodynamic quantities of a Heisenberg ferromagnet in the critical region

    International Nuclear Information System (INIS)

    Jezewski, W.

    1979-01-01

    Properties of the Bloch self-consistently renormalized spin wave approximation are analyzed near the zero-field transition temperature Tsub(m). The analysis is carried out on the basis of the application of this approximation to the Heisenberg ferromagnet involving nearest neighbour interaction. Series expansions for the resulting Helmholtz free energy, magnetization, and specific heat in the reduced temperature t=(Tsub(m)-T)/Tsub(m) are derived and the critical exponents β and α' are obtained. The limiting case of infinite spin (the classical limit) is also investigated. (author)

  20. Magneto- to electroactive transmutation of spin waves in ErMnO3.

    Science.gov (United States)

    Chaix, L; de Brion, S; Petit, S; Ballou, R; Regnault, L-P; Ollivier, J; Brubach, J-B; Roy, P; Debray, J; Lejay, P; Cano, A; Ressouche, E; Simonet, V

    2014-04-04

    The low-energy dynamical properties of the multiferroic hexagonal perovskite ErMnO3 have been studied by inelastic neutron scattering as well as terahertz and far infrared spectroscopies on a synchrotron source. From these complementary techniques, we have determined the magnon and crystal field spectra and identified a zone center magnon excitable only by the electric field of an electromagnetic wave. Using a comparison with the isostructural YMnO3 compound and crystal field calculations, we propose that this dynamical magnetoelectric process is due to the hybridization of a magnon with an electroactive crystal field transition.

  1. The influence of the spin-dependent phases of tunneling electrons on the conductance of a point ferromagnet/isolator/d-wave superconductor contact.

    Science.gov (United States)

    Vodopyanov, B P

    2010-05-12

    The influence of the spin-dependent phase shifts (SDPSs) associated with the electronic reflection and transmission amplitudes acquired by electrons upon scattering at the potential barrier on the Andreev reflection probability of electron and hole excitations for a ferromagnet/isolator/d-wave superconductor (FIS) contact and on the charge conductance of the FIS contact is studied. Various superconductor orientations are considered. It has been found that for strong ferromagnets and ultrathin interface potential for the {110} oriented d-wave superconductor the presence of the SDPS can lead to the appearance of finite-voltage peaks in the charge conductance of the F/I/d-wave superconductor contact. On the contrary, for the {100} orientation of the d-wave superconductor the presence of the SDPS can lead to restoration of the zero-voltage peak and suppression of finite-voltage peaks. The spin-dependent amplitudes of the Andreev reflection probability and energy levels of the spin-dependent Andreev bound states are found.

  2. Applications of Shock Wave Research to Developments of Therapeutic Devices.

    Science.gov (United States)

    Takayama, Kazuyoshi

    2007-06-01

    Underwater shock wave research applied to medicine started in 1980 by exploding micro lead azide pellets in water. Collaboration with urologists in the School of Medicine, Tohoku University at the same time was directed to disintegration of kidney stones by controlling shock waves. We initially proposed a miniature truncated ellipsoidal cavity for generating high-pressures enough to disintegrate the stone but gave up the idea, when encountering the Dornie Systems' invention of an extracorporeal shock wave lithotripter (ESWL). Then we confirmed its effectiveness by using 10 mg silver azide pellets and constructed our own lithotripter, which was officially approved for a clinical use in 1987. Tissue damage during ESWL was attributable to bubble collapse and we convinced it could be done in a controlled fashion. In 1996, we used 160 mJ pulsed Ho:YAG laser beam focusing inside a catheter for shock generation and applied it to the revascularization of cerebral embolism, which is recently expanded to the treatment of pulmonary infarction. Micro water jets discharged in air were so effective to dissect soft tissues preserving small blood vessels. Animal experiments are successfully performed with high frequency water jets driven by an actuator-assisted micro-pump. A metal foil is deformed at high speed by a Q-switched Nd:YAG laser beam loading. We used this technique to project micro-particles or dry drugs attached on its reverse side and extended it to a laser ablation assisted dry drug delivery or DNA introductory system.

  3. Accretion-induced spin-wandering effects on the neutron star in Scorpius X-1: Implications for continuous gravitational wave searches

    Science.gov (United States)

    Mukherjee, Arunava; Messenger, Chris; Riles, Keith

    2018-02-01

    The LIGO's discovery of binary black hole mergers has opened up a new era of transient gravitational wave astronomy. The potential detection of gravitational radiation from another class of astronomical objects, rapidly spinning nonaxisymmetric neutron stars, would constitute a new area of gravitational wave astronomy. Scorpius X-1 (Sco X-1) is one of the most promising sources of continuous gravitational radiation to be detected with present-generation ground-based gravitational wave detectors, such as Advanced LIGO and Advanced Virgo. As the sensitivity of these detectors improve in the coming years, so will power of the search algorithms being used to find gravitational wave signals. Those searches will still require integration over nearly year long observational spans to detect the incredibly weak signals from rotating neutron stars. For low mass X-ray binaries such as Sco X-1 this difficult task is compounded by neutron star "spin wandering" caused by stochastic accretion fluctuations. In this paper, we analyze X-ray data from the R X T E satellite to infer the fluctuating torque on the neutron star in Sco X-1. We then perform a large-scale simulation to quantify the statistical properties of spin-wandering effects on the gravitational wave signal frequency and phase evolution. We find that there are a broad range of expected maximum levels of frequency wandering corresponding to maximum drifts of between 0.3 - 50 μ Hz /sec over a year at 99% confidence. These results can be cast in terms of the maximum allowed length of a coherent signal model neglecting spin-wandering effects as ranging between 5-80 days. This study is designed to guide the development and evaluation of Sco X-1 search algorithms.

  4. Neutron-Scattering Study of Spin Waves in the Ferrimagnet RbNiF3

    DEFF Research Database (Denmark)

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

    1972-01-01

    -wave theory with JAB=(93.2±2)°K, JBB=-(21.1±2)°K (H=Σi>jJijS⃗i·S⃗j, S=1), and with all other exchange constants set to zero. Using these exchange constants we can satisfactorily account for other magnetic properties such as the high-temperature susceptibility, the sublattice magnetizations in a field, and two-magnon...... Raman scattering. At higher temperatures it is found that the c-axis acoustic magnons renormalize like the magnetization, whereas the high-lying optic modes are nearly temperature independent. This leads one to the physical picture in which RbNiF3 at high temperatures is viewed as a set of strongly...

  5. Change of spin-wave spectrum arising from interaction of magnons

    International Nuclear Information System (INIS)

    Prozorova, L.A.; Smirnov, A.I.

    1978-01-01

    Variation of the proper frequency of magnons with a definite wave number k=k 1 is observed in the antiferromagnetic crystal CsMnF 3 by exciting the magnons with k=k 2 . Magnon excitation is performed parametrically by microwave pumping. The density of the parametrically excited magnons is of the order of 10 17 cm -3 . The relative variation of the proper frequency (magnon spectrum shift) is approximately 10 -5 . The variation in the proper frequency is recorded and measured on observation of transition processes in a system of parametrically excited magnons. The frequencies of magnons are 10.5 and 17.5 GHz (k 1 approximately k 2 approximately 10 5 cm -1 ) and sample temperature T=1.6 K. The amplitude of four-magnon interaction inducing the spectral shift is determined and found to be T 12 /2π approximately -10 -12 Hzxcm 3

  6. Semiconductors put spin in spintronics

    International Nuclear Information System (INIS)

    Weiss, Dieter

    2000-01-01

    Electrons and holes, which carry the current in semiconductor devices, are quantum-mechanical objects characterized by a set of quantum numbers - the band index, the wave-vector (which is closely related to the electron or hole velocity) and spin. The spin, however, is one of the strangest properties of particles. In simple terms, we can think of the spin as an internal rotation of the electron, but it has no classical counterpart. The spin is connected to a quantized magnetic moment and hence acts as a microscopic magnet. Thus the electron spin can adopt one of two directions (''up'' or ''down'') in a magnetic field. The spin plays no role in conventional electronics and the current in any semiconductor device is made up of a mixture of electrons with randomly oriented spins. However, a new range of electronic devices that transport the spin of the electrons, in addition to their charge, is being developed. But the biggest obstacle to making practical ''spin electronic'' or ''spintronic'' devices so far has been finding a way of injecting spin-polarized electrons or holes into the semiconductor and then detecting them. Recently a team of physicists from the University of Wuerzburg in Germany, and also a collaboration of researchers from Tohoku University in Japan and the University of California at Santa Barbara, have found a way round these problems using either semi-magnetic or ferromagnetic semiconductors as ''spin aligners'' (R Fiederling et al. 1999 Nature 402 787; Y Ohno et al. 1999 Nature 402 790). In this article the author presents the latest breakthrough in spintronics research. (UK)

  7. Spin wave relaxation and magnetic properties in [M/Cu] super-lattices; M=Fe, Co and Ni

    International Nuclear Information System (INIS)

    Fahmi, A.; Qachaou, A.

    2009-01-01

    In this work, we study the elementary excitations and magnetic properties of the [M/Cu] super-lattices with: M=Fe, Co and Ni, represented by a Heisenberg ferromagnetic system with N atomic planes. The nearest neighbour (NN), next nearest neighbour (NNN) exchange, dipolar interactions and surface anisotropy effects are taken into account and the Hamiltonian is studied in the framework of the linear spin wave theory. In the presence of the exchange alone, the excitation spectrum E(k) and the magnetization z >/S analytical expressions are obtained using the Green's function formalism. The obtained relaxation time of the magnon populations is nearly the same in the Fe and Co-based super-lattices, while these magnetic excitations would last much longer in the Ni-based super lattice. A numerical study of the surface anisotropy and long-ranged dipolar interaction combined effects are also reported. The exchange integral values deduced from a comparison with experience for the three super-lattices are coherent.

  8. The magnetic particle in a box: Analytic and micromagnetic analysis of probe-localized spin wave modes

    Science.gov (United States)

    Adur, Rohan; Du, Chunhui; Manuilov, Sergei A.; Wang, Hailong; Yang, Fengyuan; Pelekhov, Denis V.; Hammel, P. Chris

    2015-05-01

    The dipole field from a probe magnet can be used to localize a discrete spectrum of standing spin wave modes in a continuous ferromagnetic thin film without lithographic modification to the film. Obtaining the resonance field for a localized mode is not trivial due to the effect of the confined and inhomogeneous magnetization precession. We compare the results of micromagnetic and analytic methods to find the resonance field of localized modes in a ferromagnetic thin film, and investigate the accuracy of these methods by comparing with a numerical minimization technique that assumes Bessel function modes with pinned boundary conditions. We find that the micromagnetic technique, while computationally more intensive, reveals that the true magnetization profiles of localized modes are similar to Bessel functions with gradually decaying dynamic magnetization at the mode edges. We also find that an analytic solution, which is simple to implement and computationally much faster than other methods, accurately describes the resonance field of localized modes when exchange fields are negligible, and demonstrating the accessibility of localized mode analysis.

  9. Azimuthal spin-wave excitations in magnetic nanodots over the soliton background: Vortex, Bloch, and Néel-like skyrmions

    Science.gov (United States)

    Mruczkiewicz, M.; Gruszecki, P.; Krawczyk, M.; Guslienko, K. Y.

    2018-02-01

    We study azimuthal spin-wave (SW) excitations in a circular ferromagnetic nanodot in different inhomogeneous, topologically nontrivial magnetization states, specifically, vortex, Bloch-type skyrmion, and Néel-type skyrmion states. A continuous transition between these states is realized by gradually changing the out-of-plane magnetic anisotropy and the Dzyaloshinskii-Moriya exchange interaction (DMI), and the corresponding SW spectra are calculated for each state. We observe the lifting of degeneracy of SW mode frequencies and a change in the systematics of frequency levels. The latter effect is induced by the geometric Berry phase, which occurs in SWs localized at the edge of the dot in the vortex state, and vanishes in the skyrmion states. Furthermore, channeling of edge-localized azimuthal SWs and a related large frequency splitting are observed in the skyrmion states. This is attributed to DMI-induced nonreciprocity, while the coupling of the breathing and gyrotropic modes is related to the skyrmion motion. Finally, we demonstrate efficient coupling of the dynamic magnetization to a uniform magnetic field in nanodots of noncircular symmetry in the skyrmion states.

  10. Spin-wave dynamics and exchange interactions in multiferroic NdFe3(BO3)4 explored by inelastic neutron scattering

    Science.gov (United States)

    Golosovsky, I. V.; Ovsyanikov, A. K.; Aristov, D. N.; Matveeva, P. G.; Mukhin, A. A.; Boehm, M.; Regnault, L.-P.; Bezmaternykh, L. N.

    2018-04-01

    Magnetic excitations and exchange interactions in multiferroic NdFe3(BO3)4 were studied by inelastic neutron scattering in the phase with commensurate antiferromagnetic structure. The observed spectra were analyzed in the frame of the linear spin-wave theory. It was shown that only the model, which includes the exchange interactions within eight coordination spheres, describes satisfactorily all observed dispersion curves. The calculation showed that the spin-wave dynamics is governed by the strongest antiferromagnetic intra-chain interaction and three almost the same inter-chain interactions. Other interactions, including ferromagnetic exchange, appeared to be insignificant. The overall energy balance of the antiferromagnetic inter-chain exchange interactions, which couple the moments from the adjacent ferromagnetic layers as well as within a layer, stabilizes ferromagnetic arrangement in the latter. It demonstrates that the pathway geometry plays a crucial role in forming of the magnetic structure.

  11. S, P, D, F, G-waves KN phase shifts in a constituent quark model with a spin-orbit interaction

    International Nuclear Information System (INIS)

    Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

    2002-01-01

    The I=1 and I=0 kaon-nucleon s, p, d, f, g-waves phase shifts have been calculated in a nonrelativistic quark potential model using the resonating group method (RGM). The interquark potential includes gluon exchanges with a spin-orbit interaction. This force has been determined to reproduce as well as possible the meson and baryon spectra. The same force is employed for the cluster and intercluster dynamics and the relative KN wave-function is calculated without any approximation. While some channels are correctly described, the theory is still unable to explain others

  12. Magnetic Spin-Wave Properties of Ferromagnetic Nanosystems of Various Shapes. Peculiarities of the Border Conditions Accounting in the Process of the Wavenumber Values Spectrum Finding

    Directory of Open Access Journals (Sweden)

    Volodymyr V. Kulish

    2017-09-01

    Conclusions. The obtained expressions for the spectrum of the values of the investigated spin waves’ wavenumbers can be used for a wider range of cases than the ones obtained in the previous papers dedicated to the investigated configurations of nanosystems. For a nanotube of the circular cross-section with small (compared to the inverse characteristic size of the nanotube cross-section values of the longitudinal wave number, the dependence of the latter on the transverse wave number is weak, as well as for the big longitudinal to transverse wavenumber component ratio. The obtained dependence is also represented graphically.

  13. Spins, Stalls, and Shutdowns: Pitfalls of Qualitative Policing and Security Research

    Directory of Open Access Journals (Sweden)

    Randy K. Lippert

    2015-11-01

    Full Text Available This article explores key elements of qualitative research on policing and security agencies, including barriers encountered and strategies to prevent them. While it is oft-assumed that policing/security agencies are difficult to access due to their clandestine or bureaucratic nature, this article demonstrates this is not necessarily the case, as access was gained for three distinct qualitative research projects. Yet, access and subsequent research were not without pitfalls, which we term security spins, security stalls, and security shutdowns. We illustrate how each was encountered and argue these pitfalls are akin to researchers falling into risk categories, not unlike those used by policing/security agents in their work. Before concluding we discuss methodological strategies for scholars to avoid these pitfalls and to advance research that critically interrogates the immense policing/security realm. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1601108

  14. Observation of prolonged coherence time of the collective spin wave of an atomic ensemble in a paraffin-coated 87Rb vapor cell

    International Nuclear Information System (INIS)

    Jiang Shuo; Luo Xiaoming; Chen Liqing; Ning Bo; Chen Shuai; Wang Jingyang; Zhong Zhiping; Pan Jianwei

    2009-01-01

    We report a prolonged coherence time of the collective spin wave of a thermal 87 Rb atomic ensemble in a paraffin-coated cell. The spin wave is prepared through a stimulated Raman process. The long coherence time is achieved by prolonging the lifetime of the spins with paraffin coating and minimize dephasing with optimal experimental configuration. The observation of the long-time-delayed-stimulated Stokes signal in the writing process suggests the prolonged lifetime of the prepared spins; a direct measurement of the decay of anti-Stokes signal in the reading process shows the coherence time is up to 300 μs after minimizing dephasing. This is 100 times longer than the reported coherence time in the similar experiments in thermal atomic ensembles based on the Duan-Lukin-Cirac-Zoller and its improved protocols. This prolonged coherence time sets the upper limit of the memory time in quantum repeaters based on such protocols, which is crucial for the realization of long-distance quantum communication. The previous reported fluorescence background in the writing process due to collision in a sample cell with buffer gas is also reduced in a cell without buffer gas.

  15. Metal-ligand delocalization and spin density in the CuCl{sub 2} and [CuCl{sub 4}]{sup 2−} molecules: Some insights from wave function theory

    Energy Technology Data Exchange (ETDEWEB)

    Giner, Emmanuel, E-mail: gnrmnl@unife.it; Angeli, Celestino, E-mail: anc@unife.it [Dipartimento di Scienze Chimiche e Famaceutiche, Universita di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara (Italy)

    2015-09-28

    The aim of this paper is to unravel the physical phenomena involved in the calculation of the spin density of the CuCl{sub 2} and [CuCl{sub 4}]{sup 2−} systems using wave function methods. Various types of wave functions are used here, both variational and perturbative, to analyse the effects impacting the spin density. It is found that the spin density on the chlorine ligands strongly depends on the mixing between two types of valence bond structures. It is demonstrated that the main difficulties found in most of the previous studies based on wave function methods come from the fact that each valence bond structure requires a different set of molecular orbitals and that using a unique set of molecular orbitals in a variational procedure leads to the removal of one of them from the wave function. Starting from these results, a method to compute the spin density at a reasonable computational cost is proposed.

  16. Extraordinary Electromagnetic Waves in Weakly Relativistic Degenerate Spin-1/2 Magnetized Quantum Plasmas

    Science.gov (United States)

    Li, Chun-Hua; Wang, Shao-Wei; Liu, Yun-Hao; Xia, Zhen-Wei; Zhang, Xiao-Hui; Zou, Dan-Dan

    2018-04-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11705043, 11547137 and 11605036, the Innovation Training Project for College Students in Anhui Province under Grant No 2017CXCYS222, the Doctoral Production & Learning & Research Special Fund of Hefei University of Technology under Grant No XC2015JZBZ25, and the Natural Science Foundation of Jiangxi Province under Grant Nos 20161BAB206156 and 20171BAB206044.

  17. PROCEEDINGS FROM RIKEN-BNL RESEARCH CENTER WORKSHOP: PARITY-VIOLATING SPIN ASYMMETRIES AT RHIC

    International Nuclear Information System (INIS)

    VOGELSANG, W.; PERDEKAMP, M.; SURROW, B.

    2007-01-01

    as jet and W+charrn final states and spin asymmetries in Z production, were proposed and discussed. All of the talks attracted much interest and initiated active discussions. This was a very successful workshop. It stimulated many discussions and new collaborations. We are grateful to all participants and speakers for coming to the Center, and for their excellent work. The support provided for this workshop by Dr. N. Samios and his RIKEN-BNL Research Center has been magnificent, and we are very grateful for it. We thank Brookhaven National Laboratory and the U.S. Department of Energy for providing the facilities to hold the workshop. Finally, sincere thanks go to Jane Lysik for her efficient work on organizing and running the workshop

  18. The finite element simulation analysis research of 38CrSi cylindrical power spinning

    Science.gov (United States)

    Liang, Wei; Lv, Qiongying; Zhao, Yujuan; Lv, Yunxia

    2018-01-01

    In order to grope for the influence of the main cylindrical spinning process parameters on the spinning process, this paper combines with real tube power spinning process and uses ABAQUS finite element analysis software to simulate the tube power spinning process of 38CrSi steel materials, through the analysis of the stress, strain of the part forming process, analyzes the influence of the thickness reduction and the feed rate to the forming process, and analyzes the variation of the spinning force, finally determines the reasonable main spinning process parameters combination.

  19. Optically Driven Spin Based Quantum Dots for Quantum Computing - Research Area 6 Physics 6.3.2

    Science.gov (United States)

    2015-12-15

    SECURITY CLASSIFICATION OF: This program conducted experimental and theoretical research aimed at developing an optically driven quantum dot quantum ...computer, where, the qubit is the spin of the electron trapped in a self-assembled quantum dot in InAs. Optical manipulation using the trion state...reports. In this reporting period, we discovered the nuclear spin quieting first discovered in 2008 is present in vertically coupled quantum dots but

  20. Some recent advances of shock wave physics research at the Laboratory for Shock Wave and Detonation Physics Research

    CERN Document Server

    Jing Fu Qian

    2002-01-01

    Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt...

  1. Electron Bernstein Wave Research on NSTX and PEGASUS

    International Nuclear Information System (INIS)

    Diem, S. J.; LeBlanc, B. P.; Taylor, G.; Caughman, J. B.; Bigelow, T.; Wilgen, J. B.; Garstka, G. D.; Harvey, R. W.; Preinhaelter, J.; Urban, J.; Sabbagh, S. A.

    2007-01-01

    Spherical tokamaks (STs) routinely operate in the overdense regime (ω pe >>ω ce ), prohibiting the use of standard ECCD and ECRH. However, the electrostatic electron Bernstein wave (EBW) can propagate in the overdense regime and is strongly absorbed and emitted at the electron cyclotron resonances. As such, EBWs offer the potential for local electron temperature measurements and local electron heating and current drive. A critical challenge for these applications is to establish efficient coupling between the EBWs and electromagnetic waves outside the cutoff layer. Two STs in the U.S., the National Spherical Tokamak Experiment (NSTX, at Princeton Plasma Physics Laboratory) and PEGASUS Toroidal Experiment (University of Wisconsin-Madison) are focused on studying EBWs for heating and current drive. On NSTX, two remotely steered, quad-ridged antennas have been installed to measure 8-40 GHz (fundamental, second and third harmonics) thermal EBW emission (EBE) via the oblique B-X-O mode conversion process. This diagnostic has been successfully used to map the EBW mode conversion efficiency as a function of poloidal and toroidal angles on NSTX. Experimentally measured mode conversion efficiencies of 70±20% have been measured for 15.5 GHz (fundamental) emission in L-mode discharges, in agreement with a numerical EBE simulation. However, much lower mode conversion efficiencies of 25±10% have been measured for 25 GHz (second harmonic) emission in L-mode plasmas. Numerical modeling of EBW propagation and damping on the very-low aspect ratio PEGASUS Toroidal Experiment has been performed using the GENRAY ray-tracing code and CQL3D Fokker-Planck code in support of planned EBW heating and current drive (EBWCD) experiments. Calculations were performed for 2.45 GHz waves launched with a 10 cm poloidal extent for a variety of plasma equilibrium configurations. Poloidal launch scans show that driven current is maximum when the poloidal launch angle is between 10 and 25 degrees

  2. Electron Bernstein Wave Research on CDX-U and NSTX

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C.; Jones, B.; Hosea, J.C.; Kaita, R.; LeBlanc, B.P.; Majeski, R.; Munsat, T.; Phillips, C.K.; Spaleta, J.; Wilson, J.R.; Rasmussen, D.; Bell, G.; Bigelow, T.S.; Carter, M.D.; Swain, D.W.; Wilgen, J.B.; Ram, A.K.; Bers, A.; Harvey, R.W.; Forest, C.B.

    2001-01-01

    Mode-converted electron Bernstein waves (EBWs) potentially allow the measurement of local electron temperature (Te) and the implementation of local heating and current drive in spherical torus (ST) devices, which are not directly accessible to low harmonic electron cyclotron waves. This paper reports on the measurement of X-mode radiation mode-converted from EBWs observed normal to the magnetic field on the midplane of the Current Drive Experiment-Upgrade (CDX-U) and the National Spherical Torus Experiment (NSTX) spherical torus plasmas. The radiation temperature of the EBW emission was compared to Te measured by Thomson scattering and Langmuir probes. EBW mode-conversion efficiencies of over 20% were measured on both CDX-U and NSTX. Sudden increases of mode-conversion efficiency, of over a factor of three, were observed at high-confinement-mode transitions on NSTX, when the measured edge density profile steepened. The EBW mode-conversion efficiency was found to depend on the density gradient at the mode-conversion layer in the plasma scrape-off, consistent with theoretical predictions. The EBW emission source was determined by a perturbation technique to be localized at the electron cyclotron resonance layer and was successfully used for radial transport studies. Recently, a new in-vessel antenna and Langmuir probe array were installed on CDX-U to better characterize and enhance the EBW mode-conversion process. The probe incorporates a local adjustable limiter to control and maximize the mode-conversion efficiency in front of the antenna by modifying the density profile in the plasma scrape-off where fundamental EBW mode conversion occurs. Initial results show that the mode-conversion efficiency can be increased to ∼100% when the local limiter is inserted near the mode-conversion layer. Plans for future EBW research, including EBW heating and current-drive studies, are discussed

  3. Neutron spin quantum precession using multilayer spin splitters and a phase-spin echo interferometer

    International Nuclear Information System (INIS)

    Ebisawa, Toru; Tasaki, Seiji; Kawai, Takeshi; Hino, Masahiro; Akiyoshi, Tsunekazu; Achiwa, Norio; Otake, Yoshie; Funahashi, Haruhiko.

    1996-01-01

    Neutron spin quantum precession by multilayer spin splitter has been demonstrated using a new spin interferometer. The multilayer spin splitter consists of a magnetic multilayer mirror on top, followed by a gap layer and a non magnetic multilayer mirror which are evaporated on a silicon substrate. Using the multilayer spin splitter, a polarized neutron wave in a magnetic field perpendicular to the polarization is split into two spin eigenstates with a phase shift in the direction of the magnetic field. The spin quantum precession is equal to the phase shift, which depends on the effective thickness of the gap layer. The demonstration experiments verify the multilayer spin splitter as a neutron spin precession device as well as the coherent superposition principle of the two spin eigenstates. We have developed a new phase-spin echo interferometer using the multilayer spin splitters. We present successful performance tests of the multilayer spin splitter and the phase-spin echo interferometer. (author)

  4. Kondratiev cycles and so-called long waves. The early research

    NARCIS (Netherlands)

    J. Tinbergen (Jan)

    1981-01-01

    textabstractThis paper recalls some early work of the Dutch pioneers of long-wave research which anticipated many of the contemporary debates. Various explanations which have been advanced for the existence of long waves are reviewed, and the applicability of long-wave theories in a number of

  5. Particle size, spin wave and surface effects on magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Aslibeiki, B., E-mail: b.aslibeiki@tabrizu.ac.ir [Department of Physics, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Varvaro, G.; Peddis, D. [Istituto di Struttura della Materia, National Research Council, Monterotondo Scalo, Roma 00015 (Italy); Kameli, P. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2017-01-15

    Magnesium ferrite, MgFe{sub 2}O{sub 4}, nanoparticles with a mean diameter varying from ∼6 to ∼17 nm were successfully synthesized using a simple thermal decomposition method at different annealing temperatures ranging in between 400 and 600 °C. Pure spinel ferrite nanoparticles were obtained at temperatures lower than 500 °C, while the presence of hematite (α-Fe{sub 2}O{sub 3}) impurities was observed at higher temperatures. Single-phase samples show a superparamagnetic behavior at 300 K, the saturation magnetization (M{sub s}) becoming larger with the increase of particles size. The temperature dependence of M{sub s} was explained in terms of surface spin-canting as well as spin wave excitations in the core. Using a modified Bloch law, [M{sub s}(T)=M{sub s}(0)(1−βT{sup α})], we observed a size dependent behavior of the Bloch constant β and the exponent α, whose values increase and decrease, respectively, as the particle size reduces. - Highlights: • MgFe{sub 2}O{sub 4} nanoparticles were synthesized using a thermal decomposition method. • Pure ferrite nanoparticles were obtained at temperatures lower than 500 °C. • Samples show a superparamagnetic behavior at room temperatures. • Spin wave excitations were studied using a modified Bloch law.

  6. Review of an emerging research field 'spin-orbit torques'

    International Nuclear Information System (INIS)

    Kurebayashi, Hidekazu

    2015-01-01

    This Review will provide a landscape of the recent development of one of spintronics sub-fields, so-called 'spin orbit torques'. This new class of spin torques, arising from the relativistic spin-orbit interaction in solid states, has gained a great deal of academic interest from relevant scientists and technologists. (author)

  7. Injurious effects of millimeter waves: current status of research

    International Nuclear Information System (INIS)

    Yang Zaifu; Qian Huanwen

    2005-01-01

    Millimeter waves refer to extremely high-frequency (30-300 GHz) electromagnetic oscillations. The wide application of millimeter techniques to military affairs and medicine, especially the success of non-lethal millimeter weapon gives rise to serious concern about millimeter wave damage and protection against it. Millimeter wave radiation can cause circulatory failure and subsequent death when irradiated systemically, while it can only cause direct injury to cornea and skin because of its poor penetrability (less than 1 mm into biological tissue). In this paper a brief review of cornea and skin damage and lethal effect caused by millimeter wave radiation is given. (authors)

  8. Heat and spin interconversion

    International Nuclear Information System (INIS)

    Ohnuma, Yuichi; Matsuo, Mamoru; Maekawa, Sadamichi; Saitoh, Eeiji

    2017-01-01

    Spin Seebeck and spin Peltier effects, which are mutual conversion phenomena of heat and spin, are discussed on the basis of the microscopic theory. First, the spin Seebeck effect, which is the spin-current generation due to heat current, is discussed. The recent progress in research on the spin Seebeck effect are introduced. We explain the origin of the observed sign changes of the spin Seebeck effect in compensated ferromagnets. Next, the spin Peltier effect, which is the heat-current generation due to spin current, is discussed. Finally, we show that the spin Seebeck and spin Peltier effects are summarized by Onsager's reciprocal relation and derive Kelvin's relation for the spin and heat transports. (author)

  9. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 72, RHIC SPIN COLLABORATION MEETINGS XXXI, XXXII, XXXIII

    International Nuclear Information System (INIS)

    OGAWA, A.

    2005-01-01

    The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the ''Rikagaku Kenkyusho'' (RIKEN, The Institute of Physical and Chemical Research) of Japan. The Center is dedicated to the study of strong interactions, including spin physics, lattice QCD, and RHIC physics through the nurturing of a new generation of young physicists. The RBRC has both a theory and experimental component. At present the theoretical group has 4 Fellows and 3 Research Associates as well as 11 RHIC Physics/University Fellows (academic year 2003-2004). To date there are approximately 30 graduates from the program of which 13 have attained tenure positions at major institutions worldwide. The experimental group is smaller and has 2 Fellows and 3 RHIC Physics/University Fellows and 3 Research Associates, and historically 6 individuals have attained permanent positions. Beginning in 2001 a new RIKEN Spin Program (RSP) category was implemented at RBRC. These appointments are joint positions of RBRC and RIKEN and include the following positions in theory and experiment: RSP Researchers, RSP Research Associates, and Young Researchers, who are mentored by senior RBRC Scientists. A number of RIKEN Jr. Research Associates and Visiting Scientists also contribute to the physics program at the Center. RBRC has an active workshop program on strong interaction physics with each workshop focused on a specific physics problem. Each workshop speaker is encouraged to select a few of the most important transparencies from his or her presentation, accompanied by a page of explanation. This material is collected at the end of the workshop by the organizer to form proceedings, which can therefore be available within a short time. To date there are seventy-two proceeding volumes available. The construction of a 0.6 teraflops parallel processor, dedicated to lattice QCD, begun at the Center on February 19, 1998, was completed on August 28, 1998 and is still

  10. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  11. The transmission factor of a bloch wall for spin waves whose wave vector is perpendicular to the wall (1961); Facteur de transmission d'une paroi de bloch pour des ondes de spin de vecteur d'onde normal a la paroi (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Boutron, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    When, for a ferromagnetic, the anisotropic energy takes the form E= K sin{sup 2} {alpha}, the study of the propagation of spin waves of low energy across a Bloch wall leads to a one-dimensional Schrodinger equation in which is found a potential well which has the remarkable property of being completely transparent for all values of the incident wave energy. (author) [French] Dans un ferromagnetique, lorsque la densite d'energie d'anisotropie est de la forme E= K sin{sup 2} {alpha}, l'etude de la propagation des ondes de spin de faible energie a travers une paroi de Bloch, conduit a une equation de Schrodinger a une dimension, dans laquelle figure un puits de potentiel qui a la propriete remarquable d'etre completement transparent quelle que soit l'energie de l'onde incidente. (auteur)

  12. Magnonic Crystal Theory of the Spin-Wave Frequency Gap in Low-Doped $La_{1-x}Ca_{x}MnO_{3}$ Manganites

    OpenAIRE

    Krawczyk, M.; Puszkarski, H.

    2005-01-01

    A theory of three-dimensional (3D) hypothetical magnonic crystal (conceived as the magnetic counterpart of the well-known photonic crystal) is developed and applied to explain the existence of a spin-wave frequency gap recently revealed in low-doped manganites $La_{1-x}Ca_{x}MnO_{3}$ by neutron scattering. A successful confrontation with the experimental results allows us to formulate a working hypothesis that certain manganites could be regarded as 3D magnonic crystals existing in nature.

  13. A momentum-space formulation without partial wave decomposition for scattering of two spin-half particles

    Energy Technology Data Exchange (ETDEWEB)

    Fachruddin, Imam, E-mail: imam.fachruddin@sci.ui.ac.id; Salam, Agus [Departemen Fisika, Universitas Indonesia, Depok 16424 (Indonesia)

    2016-03-11

    A new momentum-space formulation for scattering of two spin-half particles, both either identical or unidentical, is formulated. As basis states the free linear-momentum states are not expanded into the angular-momentum states, the system’s spin states are described by the product of the spin states of the two particles, and the system’s isospin states by the total isospin states of the two particles. We evaluate the Lippmann-Schwinger equations for the T-matrix elements in these basis states. The azimuthal behavior of the potential and of the T-matrix elements leads to a set of coupled integral equations for the T-matrix elements in two variables only, which are the magnitude of the relative momentum and the scattering angle. Some symmetry relations for the potential and the T-matrix elements reduce the number of the integral equations to be solved. A set of six spin operators to express any interaction of two spin-half particles is introduced. We show the spin-averaged differential cross section as being calculated in terms of the solution of the set of the integral equations.

  14. Collaborative Research: Dynamics of Electrostatic Solitary Waves on Current Layers

    Energy Technology Data Exchange (ETDEWEB)

    Pickett, Jolene S.

    2012-10-31

    The research carried out under the subject grant has provided insight into the generation of Electrostatic Solitary Waves (ESWs), which are nonlinear structures observed in space plasma data. These ESWs, appearing as pulses in the electric field time series data, represent the presence of several hundred meters to kilometer size positive potential structures, similar to champagne bubbles, where the electrons have been depleted, and which travel along Earth's magnetic field lines. The laboratory experiments carried out at the UCLA LAPD under the grant allowed us the opportunity to change various plasma and field conditions within the plasma device, and experiment with injection of suprathermal electron beams, in order to create ESWs. This then allowed us to determine the most likely method of generation of the ESWs. By comparing the properties of the ESWs observed in the LAPD to those observed in space and the plasma and field conditions under which those ESWs were observed in both locations, we were able to evaluate various ESW generation mechanisms. The findings of the laboratory experiments are that ESWs are generated through a lower hybrid instability. The ESWs observed in Earth's auroral current regions have similar characteristics to those generated by the laboratory when referenced to basic plasma and field characteristics, leading us to the conclusion that the lower hybrid drift instability is certainly a possibility for generation of the ESWs, at least in the auroral (northern/southern lights) regions. Due to space instrumentation insufficiencies and the limitations on telemetry, and thus poor time resolution, it is not possible to determine absolutely what generates these bubbles in space, but the laboratory experiments and supporting simulations have helped us to further our understanding of the processes under which they are generated. The public benefits from the findings of this research because the research is focused on current layers

  15. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  16. Analytic evidence of the equivalence of the alternating Heisenberg spin chain to the mixed spin (1, 1/2) Heisenberg chain

    International Nuclear Information System (INIS)

    Jiang Jianjun; Liu Yongjun; Tang Fei; Yang Cuihong

    2011-01-01

    We investigated the properties of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain using the spin-wave theory. The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the model are calculated to be compared with the corresponding properties of the mixed spin (1, 1/2) chain for a range of α. The results demonstrate that all the properties show similar behaviours in the small α limit, so the properties of the mixed spin (1, 1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. -- Research Highlights: →The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain are calculated. →In the small α limit, the properties of the mixed spin (1,1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. →The spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain may be of interest for some real quasi-one-dimensional molecular magnetic materials.

  17. Unified treatment of complete orthonormal sets for wave functions, and Slater orbitals of particles with arbitrary spin in coordinate, momentum and four-dimensional spaces

    International Nuclear Information System (INIS)

    Guseinov, I.I.

    2007-01-01

    The new analytical relations of complete orthonormal sets for the tensor wave functions and the tensor Slater orbitals of particles with arbitrary spin in coordinate, momentum and four-dimensional spaces are derived using the properties of tensor spherical harmonics and complete orthonormal scalar basis sets of ψ α -exponential type orbitals, φ α -momentum space orbitals and z α -hyperspherical harmonics introduced by the author for particles with spin s=0, where the α=1,0,-1,-2,.... All of the tensor wave functions obtained are complete without the inclusion of the continuum and, therefore, their group of transformations is the four-dimensional rotation group O(4). The analytical formulas in coordinate space are also derived for the overlap integrals over tensor Slater orbitals with the same screening constant. We notice that the new idea presented in this work is the combination of tensor spherical harmonics of rank s with complete orthonormal scalar sets for radial parts of ψ α -, φ α - and z α -orbitals, where s=1/2,1,3/2,2,...

  18. Spin density wave in (Fe{sub x}V{sub 3-x})S{sub 4} and the coexistence of normal and condensate states: A Moessbauer study

    Energy Technology Data Exchange (ETDEWEB)

    Embaid, B.P., E-mail: pembaid@fisica.ciens.ucv.ve [Laboratorio de Magnetismo, Escuela de Fisica, Universidad Central de Venezuela, Apartado 47586, Los Chaguaramos, Caracas 1041-A (Venezuela, Bolivarian Republic of); Gonzalez-Jimenez, F. [Laboratorio de Magnetismo, Escuela de Fisica, Universidad Central de Venezuela, Apartado 47586, Los Chaguaramos, Caracas 1041-A (Venezuela, Bolivarian Republic of)

    2013-03-15

    Iron-vanadium sulfides of the monoclinic system Fe{sub x}V{sub 3-x}S{sub 4} (1.0{<=}x{<=}2.0) have been investigated by {sup 57}Fe Moessbauer Spectroscopy in the temperature range 30-300 K. Incommensurate spin density waves (SDW) have been found in this system. An alternative treatment of the spectra allows a direct measurement of the temperature evolution of condensate density of the SDW state which follows the Maki-Virosztek formula. For composition (x=1.0) the SDW condensate is unpinned while for compositions (x>1.0) the SDW condensate is pinned. Possible causes of the pinning-unpinning SDW will be discussed. - Highlights: Black-Right-Pointing-Pointer Fe{sub x}V{sub 3-x}S{sub 4}(1.0{<=}x{<=}2.0) system was investigated by {sup 57}Fe Moessbauer Spectroscopy. Black-Right-Pointing-Pointer Incommensurate spin density wave (SDW) has been found in this system. Black-Right-Pointing-Pointer We report the temperature evolution of the condensate density of SDW state. Black-Right-Pointing-Pointer For composition (x=1.0) the SDW is unpinned while for (x>1.0) is pinned.

  19. An interactive, multitask computer system for heavy-ion physics research with the spin spectrometer: [Progress report, 1982

    International Nuclear Information System (INIS)

    Sarantites, D.G.

    1982-01-01

    The scope of this proposal is to assemble an interactive off-line data analysis system based on a DEC VAX 11/780 computer interfaced with an array processor, which is capable of meeting the needs of modern heavy-ion physics experiments involving data of large dimensionality as created in the Spin Spectrometer at the Holifield Heavy-ion Research Facility, to adapt the existing PDP 11 software for the Spin Spectrometer for this computer system in a form completely compatible with other laboratories with VAX 11 computers, and to develop new general and efficient software for automatic but fully interactive data analysis making use of an attach array processor

  20. Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors.

    Science.gov (United States)

    Hong, Seung Hwan; Choi, Han-Yong

    2013-09-11

    We investigated the characteristics of spin fluctuation mediated superconductivity employing the Eliashberg formalism. The effective interaction between electrons was modeled in terms of the spin susceptibility measured by inelastic neutron scattering experiments on single crystal La(2-x)Sr(x)CuO4 superconductors. The diagonal self-energy and off-diagonal self-energy were calculated by solving the coupled Eliashberg equation self-consistently for the chosen spin susceptibility and tight-binding dispersion of electrons. The full momentum and frequency dependence of the self-energy is presented for optimally doped, overdoped, and underdoped LSCO cuprates in a superconductive state. These results may be compared with the experimentally deduced self-energy from ARPES experiments.

  1. Inverse free electron laser beat-wave accelerator research

    International Nuclear Information System (INIS)

    Marshall, T.C.; Bhattacharjee, A.

    1993-09-01

    A calculation on the stabilization of the sideband instability in the free electron laser (FEL) and inverse FEL (IFEL) was completed. The issue arises in connection with the use of a tapered (''variable-parameter'') undulator of extended length, such as might be used in an ''enhanced efficiency'' traveling-wave FEL or an IFEL accelerator. In addition, the FEL facility at Columbia was configured as a traveling wave amplifier for a 10-kW signal from a 24-GHz magnetron. The space charge field in the bunches of the FEL was measured. Completed work has been published

  2. Research Update: Spin transfer torques in permalloy on monolayer MoS2

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2016-03-01

    Full Text Available We observe current induced spin transfer torque resonance in permalloy (Py grown on monolayer MoS2. By passing rf current through the Py/MoS2 bilayer, field-like and damping-like torques are induced which excite the ferromagnetic resonance of Py. The signals are detected via a homodyne voltage from anisotropic magnetoresistance of Py. In comparison to other bilayer systems with strong spin-orbit torques, the monolayer MoS2 cannot provide bulk spin Hall effects and thus indicates the purely interfacial nature of the spin transfer torques. Therefore our results indicate the potential of two-dimensional transition-metal dichalcogenide for the use of interfacial spin-orbitronics applications.

  3. Proceedings of RIKEN BNL Research Center Workshop, RHIC Spin Physics V, Volume 32, February 21, 2001

    International Nuclear Information System (INIS)

    BUNCE, G.; SAITO, N.; VIGDOR, S.; ROSER, T.; SPINKA, H.; ENYO, H.; BLAND, L.C.; GURYN, W.

    2001-01-01

    The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the ''Rikagaku Kenkysho'' (RIKEN, The Institute of Physical and Chemical Research) of Japan. The Center is dedicated to the study of strong interactions, including spin physics, lattice QCD and RHIC physics through the nurturing of a new generation of young physicists. During the fast year, the Center had only a Theory Group. In the second year, an Experimental Group was also established at the Center. At present, there are seven Fellows and nine post dots in these two groups. During the third year, we started a new Tenure Track Strong Interaction Theory RHIC Physics Fellow Program, with six positions in the academic year 1999-2000; this program will increase to include eleven theorists in the next academic year, and, in the year after, also be extended to experimental physics. In addition, the Center has an active workshop program on strong interaction physics, about ten workshops a year, with each workshop focused on a specific physics problem. Each workshop speaker is encouraged to select few of the most important transparencies from his or her presentation, accompanied by a page of explanation. This material is collected at the end of the workshop by the organizer to form proceedings, which can therefore be available within a short time. The construction of a 0.6 teraflop parallel processor, which was begun at the Center on February 19, 1998, was completed on August 28, 1998

  4. Drift waves in a nonuniform plasma. Research report

    International Nuclear Information System (INIS)

    Sanuki, H.; Schmidt, G.

    1975-02-01

    An eigenvalue equation describing the propagation of collisionless electrostatic drift waves in a magnetoplasma, with an arbitrary one dimensional density profile is derived. It is shown that in general several different waveforms exist each with its respective dispersion relation. A special density profile was analyzed in detail. (U.S.)

  5. Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiang; Schmehr, Julian L.; Islam, Zahirul; Porter, Zach; Zoghlin, Eli; Finkelstein, Kenneth; Ruff, Jacob P. C.; Wilson, Stephen D.

    2018-01-09

    Materials that exhibit both strong spin–orbit coupling and electron correlation effects are predicted to host numerous new electronic states. One prominent example is the Jeff = 1/2 Mott state in Sr2IrO4, where introducing carriers is predicted to manifest high temperature superconductivity analogous to the S=1/2 Mott state of La2CuO4. While bulk super- conductivity currently remains elusive, anomalous quasiparticle behaviors paralleling those in the cuprates such as pseudogap formation and the formation of a d-wave gap are observed upon electron-doping Sr2IrO4. Here we establish a magnetic parallel between electron-doped Sr2IrO4 and hole-doped La2CuO4 by unveiling a spin density wave state in electron-doped Sr2IrO4. Our magnetic resonant X-ray scattering data reveal the presence of an incom- mensurate magnetic state reminiscent of the diagonal spin density wave state observed in the monolayer cuprate (La1-xSrx)2CuO4. This link supports the conjecture that the quenched Mott phases in electron-doped Sr2IrO4 and hole-doped La2CuO4 support common competing electronic phases.

  6. Spin-orbit and spin-lattice coupling

    International Nuclear Information System (INIS)

    Bauer, Gerrit E.W.; Ziman, Timothy; Mori, Michiyasu

    2014-01-01

    We pursued theoretical research on the coupling of electron spins in the condensed matter to the lattice as mediated by the spin-orbit interaction with special focus on the spin and anomalous Hall effects. (author)

  7. [Research on vigilance detection based on pulse wave].

    Science.gov (United States)

    Cao, Yong; Jiao, Xuejun; Pan, Jinjin; Jiang, Jin; Fu, Jiahao; Xu, Fenggang; Yang, Hanjun

    2017-12-01

    This paper studied the rule for the change of vigilance based on pulse wave. 10 participants were recruited in a 95-minute Mackworth clock test (MCT) experiment. During the experiment, the vigilance of all participants were evaluated by Karolinska sleepiness scale (KSS) and Stanford sleepiness scale (SSS), and behavior data (the reaction time and the accuracy of target) and pulse wave signal of the participants were recorded simultaneously. The result indicated that vigilance of the participants can be divided into 3 classes: the first 30 minutes for high vigilance level, the middle 30 minutes for general vigilance level, and the last 30 minutes for low vigilance level. Besides, time domain features such as amplitude of secondary peak, amplitude of peak and the latency of secondary peak decreased with the decrease of vigilance, while the amplitude of troughs increased. In terms of frequency domain features, the energy of 4 frequency band including 8.600 ~ 9.375 Hz, 11.720 ~ 12.500 Hz, 38.280 ~ 39.060 Hz and 39.060 ~ 39.840 Hz decreased with the decrease of vigilance. Finally, under the recognition model established by the 8 characteristics mentioned above, the average accuracy of three-classification results over the 10 participants was as high as 88.7%. The results of this study confirmed the feasibility of pulse wave in the evaluation of vigilance, and provided a new way for the real-time monitoring of vigilance.

  8. Event generator for RHIC spin physics. Proceedings of RIKEN BNL Research Center workshop: Volume 11

    International Nuclear Information System (INIS)

    1998-01-01

    A major objective of the workshop was to establish a firm collaboration to develop suitable event generators for the spin physics program at RHIC. With the completion of the Relativistic Heavy Ion Collider (RHIC) as a polarized collider a completely new domain of high-energy spin physics will be opened. The planned studies address the spin structure of the nucleon, tests of the standard model, and transverse spin effects in initial and final states. RHIC offers the unique opportunity to pursue these studies because of its high and variable energy, 50 ≤ √s ≤ 500 GeV, high polarization, 70%, and high luminosity, 2 x 10 32 cm -2 sec -1 or more at 500 GeV. To maximize the output from the spin program at RHIC, the understanding of both experimental and theoretical systematic errors is crucial. It will require full-fledged event generators, to simulate the processes of interest in great detail. The history of event generators shows that their development and improvement are ongoing processes taking place in parallel to the physics analysis by various experimental groups. The number of processes included in the generators has been increasing and the precision of their predictions is being improved continuously. This workshop aims at getting this process well under way for the spin physics program at RHIC, based on the first development in this direction, SPHINX

  9. Chiral Spin Texture in the Charge-Density-Wave Phase of the Correlated Metallic Pb /Si (111 ) Monolayer

    Science.gov (United States)

    Tresca, C.; Brun, C.; Bilgeri, T.; Menard, G.; Cherkez, V.; Federicci, R.; Longo, D.; Debontridder, F.; D'angelo, M.; Roditchev, D.; Profeta, G.; Calandra, M.; Cren, T.

    2018-05-01

    We investigate the 1 /3 monolayer α -Pb /Si (111 ) surface by scanning tunneling spectroscopy (STS) and fully relativistic first-principles calculations. We study both the high-temperature √{3 }×√{3 } and low-temperature 3 ×3 reconstructions and show that, in both phases, the spin-orbit interaction leads to an energy splitting as large as 25% of the valence-band bandwidth. Relativistic effects, electronic correlations, and Pb-substrate interaction cooperate to stabilize a correlated low-temperature paramagnetic phase with well-developed lower and upper Hubbard bands coexisting with 3 ×3 periodicity. By comparing the Fourier transform of STS conductance maps at the Fermi level with calculated quasiparticle interference from nonmagnetic impurities, we demonstrate the occurrence of two large hexagonal Fermi sheets with in-plane spin polarizations and opposite helicities.

  10. Electron Bernstein Wave Research on the National Spherical Torus Experiment

    International Nuclear Information System (INIS)

    Taylor, G.; Bers, A.; Bigelow, T.S.; Carter, M.D.; Caughman, J.B.; Decker, J.; Diem, S.; Efthimion, P.C.; Ershov, N.M.; Fredd, E.; Harvey, R.W.; Hosea, J.; Jaeger, F.; Preinhaelter, J.; Ram, A.K.; Rasmussen, D.A.; Smirnov, A.P.; Wilgen, J.B.; Wilson, J.R.

    2005-01-01

    Off-axis electron Bernstein wave current drive (EBWCD) may be critical for sustaining noninductive high-beta National Spherical Torus Experiment (NSTX) plasmas. Numerical modeling results predict that the ∼100 kA of off-axis current needed to stabilize a solenoid-free high-beta NSTX plasma could be generated via Ohkawa current drive with 3 MW of 28 GHz EBW power. In addition, synergy between EBWCD and bootstrap current may result in a 10% enhancement in current-drive efficiency with 4 MW of EBW power. Recent dual-polarization EBW radiometry measurements on NSTX confirm that efficient coupling to EBWs can be readily accomplished by launching elliptically polarized electromagnetic waves oblique to the confining magnetic field, in agreement with numerical modeling. Plans are being developed for implementing a 1 MW, 28 GHz proof-of-principle EBWCD system on NSTX to test the EBW coupling, heating and current-drive physics at high radio-frequency power densities

  11. Gas-gun facility for shock wave research at BARC

    International Nuclear Information System (INIS)

    Gupta, S.C.; Jyoti, G.; Suresh, N.; Sikka, S.K.; Chidambaram, R.; Agarwal, R.G.; Roy, S.; Kakodkar, A.

    1995-01-01

    For carrying out shock-wave experiments on materials, we have built a 63 mm diameter gas-gun facility at our laboratory. It is capable of accelerating projectiles (about half kg in weight) to velocities up to 1 km/s using N 2 and He gases. These on impacting a target generate shock pressures up to 40 GPa, depending upon the impedance of the impactor and the target. The barrel of the gun is slotted so that a keyed projectile can be fired for combined compression- shear studies. Large samples can be shocked (about 60 mm diameter and 5-10 mm thick), with pressures lasting for a few microseconds. The gun is similar in design to the one at Washington State University. A number of diagnostic techniques have also been developed. These include measurement of projectile velocity, tilt between the impactor and the target, shock velocity in the target, and time resolved in-material stress wave histories in the shock loaded samples. Recovery capsules have also been made to retrieve shocked samples on unloading, which are then analysed using microscopic techniques like x-ray diffraction, Raman and electron microscopy. The gun has been performing well and has already been used for a few phase transition studies. (author). 73 refs., 42 figs

  12. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  13. Mechanical design of a rotary balance system for NASA. Langley Research Center's vertical spin tunnel

    Science.gov (United States)

    Allred, J. W.; Fleck, V. J.

    1992-01-01

    A new lightweight Rotary Balance System is presently being fabricated and installed as part of a major upgrade to the existing 20 Foot Vertical Spin Tunnel. This upgrade to improve model testing productivity of the only free spinning vertical wind tunnel includes a modern fan/drive and tunnel control system, an updated video recording system, and the new rotary balance system. The rotary balance is a mechanical apparatus which enables the measurement of aerodynamic force and moment data under spinning conditions (100 rpm). This data is used in spin analysis and is vital to the implementation of large amplitude maneuvering simulations required for all new high performance aircraft. The new rotary balance system described in this report will permit greater test efficiency and improved data accuracy. Rotary Balance testing with the model enclosed in a tare bag can also be performed to obtain resulting model forces from the spinning operation. The rotary balance system will be stored against the tunnel sidewall during free flight model testing.

  14. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  15. The Basic Research for Pulverization of Rice Using Underwater Shock Wave by Electric Discharge

    Directory of Open Access Journals (Sweden)

    M Ide

    2016-09-01

    Full Text Available In recent years, the food self-support rate of Japan is 40%, and this value is the lowest level in major developed countries. This reason includes decreasing of diverting rice consumption in Japan and increasing abandonment of cultivation. Therefore, these problems are solved by using rice powder instead of expensive flour, and we manage to increase the food selfsupport rate. Previously, the rice powder is manufactured by two methods. One is dry type, and the other is wet type. The former is the method getting rice powder by running dried rice to rotating metal, and has a problem which that starch is damaged by heat when processing was performed. The latter is performed same method against wet rice, and has a problem which a large quantity of water is used. As a method to solve these problems, an underwater shock wave is used. Shock wave is the pressure wave which is over speed of sound by discharging high energy in short time. Propagating shock wave in water is underwater shock wave. The characters of underwater shock wave are long duration of shock wave because water density is uniform, water is low price and easy to get and not heat processing. Thinking of industrialization, the electric discharge is used as the generating source of underwater shock wave in the experiment. As the results, the efficiency of obtaining enough grain size, 100ìm, of rice powder was too bad only using the simple processing using underwater shock wave. Therefore, in Okinawa National College of Technology collaborating with us, obtaining rice powder with higher efficiency by using converged underwater shock wave is the goal of this research. In this research, the underwater shock wave with equal energy of the experimental device of underwater shock wave is measured by the optical observation. In addition, the appearance converging underwater shock wave is simulated by numerical analysis, and the pressure appreciation rate between the first wave and converged

  16. Spin current evolution in the separated spin-up and spin-down quantum hydrodynamics

    International Nuclear Information System (INIS)

    Trukhanova, Mariya Iv.

    2015-01-01

    We have developed a method of quantum hydrodynamics (QHD) that describes particles with spin-up and with spin-down in separate. We have derived the equation of the spin current evolution as a part of the set of the quantum hydrodynamics equations that treat particles with different projection of spin on the preferable direction as two different species. We have studied orthogonal propagation of waves in the external magnetic field and determined the contribution of quantum corrections due to the Bohm potential and to magnetization energy of particles with different projections of spin in the spin-current wave dispersion. We have analyzed the limits of weak and strong magnetic fields. - Highlights: • We derive the spin current equation for particles with different projection of spin. • We predict the contribution of Bohm potential to the dynamics of spin current. • We derive the spin-current wave in the system of spin-polarized particles. • We study the propagation of spin-acoustic wave in magnetized dielectrics.

  17. Electron Bernstein Wave Research on NSTX and CDX-U

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C.; Jones, B.; Bell, G.L.; Bers, A.; Bigelow, T.S.; Carter, M.D.; Harvey, R.W.; Ram, A.K.; Rasmussen, D.A.; Smirnov, A.P.; Wilgen, J.B.; Wilson, J.R.

    2003-01-01

    Studies of thermally emitted electron Bernstein waves (EBWs) on CDX-U and NSTX, via mode conversion (MC) to electromagnetic radiation, support the use of EBWs to measure the Te profile and provide local electron heating and current drive (CD) in overdense spherical torus plasmas. An X-mode antenna with radially adjustable limiters successfully controlled EBW MC on CDX-U and enhanced MC efficiency to ∼ 100%. So far the X-mode MC efficiency on NSTX has been increased by a similar technique to 40-50% and future experiments are focused on achieving * 80% MC. MC efficiencies on both machines agree well with theoretical predictions. Ray tracing and Fokker-Planck modeling for NSTX equilibria are being conducted to support the design of a 3 MW, 15 GHz EBW heating and CD system for NSTX to assist non-inductive plasma startup, current ramp up, and to provide local electron heating and CD in high beta NSTX plasmas

  18. Preliminary research on design of traveling wave reactor

    International Nuclear Information System (INIS)

    Yan Mingyu; Chen Bin; Feng Linna; Zhang Yong

    2015-01-01

    An engineering feasible conceptual core design of large scale (e.g. 1OOOMWe output) TWR is proposed with investigation and qualitative optimization on the proper design of fuel element structure, fuel pellet, liquid metal filling gap, fuel assembly structure, core reflector and shielding and shutdown control rods. The optimized design presents a flatten radial neutron flux with a better equivalent state distribution, which means the long term burning state could be defined by initial core design and further corrected by the travelling wave progress. The optimized fuel structure improves the flow distribution between the central, parallel and corner channels. Furthermore, the power control of TWR could be implemented by the adjusting of coolant pump rotation speed as the change of coolant flow. Though the load rejection and power control between 15% to 100% nominal power could not be fulfilled by flow control without the participation of bank A control rods. (authors)

  19. Superconductivity and spin fluctuations

    International Nuclear Information System (INIS)

    Scalapino, D.J.

    1999-01-01

    The organizers of the Memorial Session for Herman Rietschel asked that the author review some of the history of the interplay of superconductivity and spin fluctuations. Initially, Berk and Schrieffer showed how paramagnon spin fluctuations could suppress superconductivity in nearly-ferromagnetic materials. Following this, Rietschel and various co-workers wrote a number of papers in which they investigated the role of spin fluctuations in reducing the Tc of various electron-phonon superconductors. Paramagnon spin fluctuations are also believed to provide the p-wave pairing mechanism responsible for the superfluid phases of 3 He. More recently, antiferromagnetic spin fluctuations have been proposed as the mechanism for d-wave pairing in the heavy-fermion superconductors and in some organic materials as well as possibly the high-Tc cuprates. Here the author will review some of this early history and discuss some of the things he has learned more recently from numerical simulations

  20. Public acceptance of fusion energy and scientific feasibility of a fusion reactor. Spin-off effects of fusion research and development

    International Nuclear Information System (INIS)

    Morino, Nobuyuki; Ogawa, Yuichi

    1998-01-01

    It is observed that new and sophisticated technologies developed through research and development in relation to magnetic confinement fusion have been transferred to other industrial and scientific fields with remarkable spin-off effects. Approximately 10 years ago, the Japan Atomic Industrial Forum (JAIF) has investigated technical transfer and spin-off effects of fusion technologies developed in Japan. The essence of the results of this investigation as well as high technologies developed in the last decade, some of which are in the early stage of technical spin-off, are described. It is additionally explained that independent technical development conducted by our country as well as by engineers themselves is important in achieving effective spin-off. An outline of scientific spin-off effects is also described, including utilization technologies of fusion reactions besides those for energy production purposes, the progress of scientific understanding in the course of fusion research, and scientific information transfer and communication with other fields. (author)

  1. Waves and turbulences studies in plasmas: ten years of research on quiescent plasmas at the Brazilian Space Research National Institute

    International Nuclear Information System (INIS)

    Ferreira, J.L.

    1991-01-01

    Quiescent plasmas generated by thermionic discharges and surface confined by multipole magnetic fields have been used in basic plasma research since 1973. The first machine was developed at UCLA (USA) to produce an uniform plasma for beam and waves studies in large cross section plasmas. A double quiescent plasma machine was constructed at the plasma laboratory of INPE in 1981, it began its operation producing linear ion-acoustic waves in an Argon plasma. Later on non linear ion acoustic waves and solitons were studied in plasma containing several species of negative and positive ions. The anomalous particle transport across multipole magnetic fields were also investigated. An anomalous resistivity associated with an ion acoustic turbulence is responsible for the formation of a small amplitude double-layer. The existence of a bootstrap mechanism is shown experimentally. Today, the main interest is toward the generation of Langmuir waves in non uniform plasmas. An experimental study on Langmuir wave generation using a grid system is been carried on. A magnetized quiescent plasma device for studies of whistle wave generation is been constructed. This machine will make possible future studies on several wave modes of magnetized plasmas. (author). 31 refs, 16 figs

  2. [Research progress of Terahertz wave technology in quality measurement of food and agricultural products].

    Science.gov (United States)

    Yan, Zhan-Ke; Zhang, Hong-Jian; Ying, Yi-Bin

    2007-11-01

    The quality concern of food and agricultural products has become more and more significant. The related technologies for nondestructive measurement or quality control of food products have been the focus of many researches. Terahertz (THz) radiation, or THz wave, the least explored region of the spectrum, is the electromagnetic wave that lies between mid-infrared and microwave radiation, which has very important research and application values. THz spectroscopy and THz imaging technique are the two main applications of THz wave. During the past decade, THz waves have been used to characterize the electronic, vibrational and compositional properties of solid, liquid and gas phase materials. Recently, THz technology has gained a lot of attention of researchers in various fields from biological spectral analysis to bio-medical imaging due to its unique features compared with microwave and optical waves. In the present paper, the properties of THz wave and its uniqueness in sensing and imaging applications were discussed. The most recent researches on THz technology used in food quality control and agricultural products inspection were summarized. The prospect of this novel technology in agriculture and food industry was also discussed.

  3. Inverse spin Hall effect by spin injection

    Science.gov (United States)

    Liu, S. Y.; Horing, Norman J. M.; Lei, X. L.

    2007-09-01

    Motivated by a recent experiment [S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176 (2006)], the authors present a quantitative microscopic theory to investigate the inverse spin-Hall effect with spin injection into aluminum considering both intrinsic and extrinsic spin-orbit couplings using the orthogonalized-plane-wave method. Their theoretical results are in good agreement with the experimental data. It is also clear that the magnitude of the anomalous Hall resistivity is mainly due to contributions from extrinsic skew scattering.

  4. Wave Energy from the North Sea: Experiences from the Lysekil Research Site

    Science.gov (United States)

    Leijon, Mats; Boström, Cecilia; Danielsson, Oskar; Gustafsson, Stefan; Haikonen, Kalle; Langhamer, Olivia; Strömstedt, Erland; Stålberg, Magnus; Sundberg, Jan; Svensson, Olle; Tyrberg, Simon; Waters, Rafael

    2008-05-01

    This paper provides a status update on the development of the Swedish wave energy research area located close to Lysekil on the Swedish West coast. The Lysekil project is run by the Centre for Renewable Electric Energy Conversion at Uppsala University. The project was started in 2004 and currently has permission to run until the end of 2013. During this time period 10 grid-connected wave energy converters, 30 buoys for studies on environmental impact, and a surveillance tower for monitoring the interaction between waves and converters will be installed and studied. To date the research area holds one complete wave energy converter connected to a measuring station on shore via a sea cable, a Wave Rider™ buoy for wave measurements, 25 buoys for studies on environmental impact, and a surveillance tower. The wave energy converter is based on a linear synchronous generator which is placed on the sea bed and driven by a heaving point absorber at the ocean surface. The converter is directly driven, i.e. it has no gearbox or other mechanical or hydraulic conversion system. This results in a simple and robust mechanical system, but also in a somewhat more complicated electrical system.

  5. Experimental Research on the Characteristic of a Generator Used in Wave Energy Conversion

    Science.gov (United States)

    Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Wu, Guoheng

    2018-01-01

    Due to the environmental issues like global warming and pollution, the exploration for ocean energy becomes important. Selecting the suitable generator for wave energy generation system is essential to improve the efficiency of power generation system. Thus, the object of the research is the generator of a self-adaptation inversion type wave energy absorption device. The major focus of this paper is the characteristics and the technique of the generator used in prototype. By setting up the generator performance test platform, the output voltage, efficiency and performance of the generator are tested to select the suitable generator for the wave energy generating system.

  6. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, RHIC SPIN COLLABORATION MEETING VI, VOLUME 36

    International Nuclear Information System (INIS)

    BLAND, L.; SAITO, N.

    2001-01-01

    The sixth meeting of the RHIC Spin Collaboration (RSC) took place on October 1, 2001 at Brookhaven National Laboratory. RHIC is now in its second year of operation for physics production and the first polarized proton collision run at √s=200 GeV is expected to start in eight weeks. The RSC has developed a plan for this coming run through two previous meetings, RHIC Spin Physics III (August 3, 2000) and IV (October 13-14, 2000). We requested the following: two weeks of polarized proton studies in AGS, three weeks of polarized collider commissioning, and five weeks of polarized proton physics run. As a result, we have obtained all we asked and the above plans are implemented in the current operation schedule. The focus of the present meeting was to bring all involved in the RHIC Spin activities up-to-date on the progress of machine development, theory issues, and experimental issues. This meeting was right after the Program Advisory Committee (PAC) meeting and it started with the comments on the PAC discussion by Gerry Bunce, who was informed about the PAC deliberations by Tom Kirk. The PAC was fully supportive to complete the proposed spin program within the currently available budget for RHIC run 2 operations. Gerry further explained the expected luminosity to be ∫ Ldt = 0.5 pb -1 per week, reflecting the current machine status. The introductory session also had a talk from Werner Vogelsang that reviewed the progress in perturbative QCD theory focused on spin effects

  7. Data analysis of gravitational-wave signals from spinning neutron stars. IV. An all-sky search

    International Nuclear Information System (INIS)

    Astone, Pia; Borkowski, Kazimierz M.; Jaranowski, Piotr; Krolak, Andrzej

    2002-01-01

    We develop a set of data analysis tools for a realistic all-sky search for continuous gravitational-wave signals and we test our tools against simulated data. The aim of the paper is to prepare for an analysis of the real data from the EXPLORER bar detector; however, the methods that we present apply both to data from the resonant bar detectors that are currently in operation and the laser interferometric detectors that are in the final stages of construction and commissioning. With our techniques we shall be able to perform an all-sky coherent search of 2 days of data from the EXPLORER detector for a frequency bandwidth of 0.76 Hz in one month with 250 Mflops computing power. This search will detect all the continuous gravitational-wave signals with the dimensionless amplitude larger than 2.8x10 -23 with 99% confidence, assuming that the noise in the detector is Gaussian

  8. Soft mode and energy gap in spin wave spectrum for a second order orientation phase transition. AFMR in YFe3

    International Nuclear Information System (INIS)

    Balbashov, A.M.; Berezin, A.G.; Gufan, Yu.M.; Kolyadko, G.S.; Marchukov, P.Yu.; Rudashevskij, E.G.

    1987-01-01

    A pronounced energy gap of a nonmagnetoelastic origin is observed experimentally in the spectrum of the low-frequency (quasiferromagnetic) antiferromagnetic resonance branch during a second order spin-flip phase transition in an external magnetic field directed along the a axis of the rhombic weak ferromagnetic YFeO 3 . From the theory developed which takes into account the susceptibility along the antiferromagnetism axis and dissipation processes, it follows that beside the usual AFMR oscillatory branches there should also be a relaxation mode which is ''soft'' fo the given transition. The magnitude of the energy gaps, the values of the kinetic coefficients, Dzyaloshinsky field strengths and ratio of the longitudinal susceptibility to the transverse susceptibility are determined by analyzing the experimental data obtained in fields up to 130 kOe in the frequency range from 60 to 400 GHz at room temperature

  9. Precise real-time polarization measurement of terahertz electromagnetic waves by a spinning electro-optic sensor.

    Science.gov (United States)

    Yasumatsu, Naoya; Watanabe, Shinichi

    2012-02-01

    We propose and develop a method to quickly and precisely determine the polarization direction of coherent terahertz electromagnetic waves generated by femtosecond laser pulses. The measurement system consists of a conventional terahertz time-domain spectroscopy system with the electro-optic (EO) sampling method, but we add a new functionality in the EO crystal which is continuously rotating with the angular frequency ω. We find a simple yet useful formulation of the EO signal as a function of the crystal orientation, which enables a lock-in-like detection of both the electric-field amplitude and the absolute polarization direction of the terahertz waves with respect to the probe laser pulse polarization direction at the same time. The single measurement finishes around two periods of the crystal rotations (∼21 ms), and we experimentally prove that the accuracy of the polarization measurement does not suffer from the long-term amplitude fluctuation of the terahertz pulses. Distribution of the measured polarization directions by repeating the measurements is excellently fitted by a gaussian distribution function with a standard deviation of σ = 0.56°. The developed technique is useful for the fast direct determination of the polarization state of the terahertz electromagnetic waves for polarization imaging applications as well as the precise terahertz Faraday or Kerr rotation spectroscopy.

  10. ElectroEncephaloGraphics: Making waves in computer graphics research.

    Science.gov (United States)

    Mustafa, Maryam; Magnor, Marcus

    2014-01-01

    Electroencephalography (EEG) is a novel modality for investigating perceptual graphics problems. Until recently, EEG has predominantly been used for clinical diagnosis, in psychology, and by the brain-computer-interface community. Researchers are extending it to help understand the perception of visual output from graphics applications and to create approaches based on direct neural feedback. Researchers have applied EEG to graphics to determine perceived image and video quality by detecting typical rendering artifacts, to evaluate visualization effectiveness by calculating the cognitive load, and to automatically optimize rendering parameters for images and videos on the basis of implicit neural feedback.

  11. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER, VOLUME 37, RHIC SPIN COLLABORATION MEETING VI (PART 2)

    International Nuclear Information System (INIS)

    Bland, L.; Saito, N.

    2001-01-01

    The second part of the sixth RHIC Spin Collaboration (RSC) meeting was held on November 15, 2001 at Brookhaven National Laboratory. Previous meetings have elaborated on the new generation of proton spin-structure studies (e.g. gluon polarization and flavor separation of q and bar q polarizations via real W ± production) enabled by studying polarized proton collisions at energies and momentum transfers where perturbative QCD models are expected to be applicable. The focus of this meeting was on many of the experimental issues that must be resolved to achieve these physics goals. This summary is written with the benefit of hindsight following the completion of the first-ever run of a polarized proton collider. This first run can be considered as a successfully completed milestone of the RHIC Spin Collaboration. Other milestones remain important. Long term machine items were identified in Waldo Mackay's talk, the most important being the completion of the spin rotator magnets that will be installed in 2002 to allow the flexible orientation of the proton beam polarization at the PHENM and STAR experiments. At the meeting Waldo discussed a stronger partial snake magnet for the AGS as a means of producing highly polarized proton beams to inject into RHIC. Developments subsequent to this meeting suggest that a superconducting helical dipole magnet may be feasible for the AGS, and is likely to be needed to achieve the 70% beam polarization in RHIC. Longer term items were also presented, including potential increases in luminosity by the addition of electron cooling to RHIC and the possibility of increasing the collision energy by ∼20% by replacement of the DX magnets. These items could be considered for a second generation of RHIC spin experiments. The other topics covered at the meeting were related to polarimetry and to the absolute calibration of the proton beam polarization in RHIC. These topics were divided into short- and long-term solutions to polarimetry issues

  12. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER, VOLUME 37, RHIC SPIN COLLABORATION MEETING VI (PART 2).

    Energy Technology Data Exchange (ETDEWEB)

    BLAND, L.; SAITO, N.

    2001-11-15

    The second part of the sixth RHIC Spin Collaboration (RSC) meeting was held on November 15, 2001 at Brookhaven National Laboratory. Previous meetings have elaborated on the new generation of proton spin-structure studies (e.g. gluon polarization and flavor separation of q and {bar q} polarizations via real W{sup {+-}} production) enabled by studying polarized proton collisions at energies and momentum transfers where perturbative QCD models are expected to be applicable. The focus of this meeting was on many of the experimental issues that must be resolved to achieve these physics goals. This summary is written with the benefit of hindsight following the completion of the first-ever run of a polarized proton collider. This first run can be considered as a successfully completed milestone of the RHIC Spin Collaboration. Other milestones remain important. Long term machine items were identified in Waldo Mackay's talk, the most important being the completion of the spin rotator magnets that will be installed in 2002 to allow the flexible orientation of the proton beam polarization at the PHENM and STAR experiments. At the meeting Waldo discussed a stronger partial snake magnet for the AGS as a means of producing highly polarized proton beams to inject into RHIC. Developments subsequent to this meeting suggest that a superconducting helical dipole magnet may be feasible for the AGS, and is likely to be needed to achieve the 70% beam polarization in RHIC. Longer term items were also presented, including potential increases in luminosity by the addition of electron cooling to RHIC and the possibility of increasing the collision energy by {approx}20% by replacement of the DX magnets. These items could be considered for a second generation of RHIC spin experiments. The other topics covered at the meeting were related to polarimetry and to the absolute calibration of the proton beam polarization in RHIC. These topics were divided into short- and long-term solutions to

  13. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  14. Experimental research of isospin and spin exotic nuclei with an ion guide and γ multidetectors

    International Nuclear Information System (INIS)

    Astier, A.

    1992-04-01

    This work is concerned with nuclear studies of isospin and spin exotic nuclei by two complementary approaches: on-line radioactivity and fusion-evaporation reactions. An ion guide coupled to the SARA accelerator allowed the study of very refractory and short lived (down to 1 ms) elements. Using the 238 U (α 40 MeV, f) reaction to produce very neutron-rich radioisotopes, all mass chains from A=96 to 122 have been scanned by conventional nuclear spectroscopy. More than 60 production yields have been measured. The comparison of proton and α induced fission yields shows the predominance of symmetric fission around A=115 for α beam. The collective high spin states structures observed in the A=190 mass region are studied with different γ multidetectors

  15. Topological aspect and the pairing symmetries on spin-triplet chiral p-wave superconductor under strain

    Science.gov (United States)

    Imai, Yoshiki; Sigrist, Manfred

    2018-05-01

    Motivated by recent experiments on Sr2RuO4, the effect of uniaxial strain on the chiral p-wave superconductor is discussed. We study particularly the relation between the topological indices and different pairing states in the superconducting phase through the thermal Hall conductivity, which is proportional to temperature and the Chern number in the very low-temperature limit. We show that the temperature-dependence of the thermal Hall conductivity under uniaxial strain depends strongly on the form of the pairing state. The obtained result may provide a possible experimental probe for the pairing structure in Sr2RuO4.

  16. Spin wave and percolation studies in epitaxial La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ettayfi, A. [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco); Moubah, R., E-mail: reda.moubah@hotmail.fr [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco); Hlil, E.K. [Institut Néel, CNRS, Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France); Colis, S.; Lenertz, M.; Dinia, A. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 UDS-CNRS (UDS-ECPM), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Lassri, H. [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco)

    2016-07-01

    We investigate the magnetic and transport properties of high quality La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films grown by pulsed laser deposition. X-ray diffraction shows that the deposited films are epitaxial with the expected pseudo-cubic structure. Using the spin wave theory, the temperature dependence of magnetization was satisfactory modeled at low temperature, in which several fundamental magnetic parameters were obtained (spin wave stiffness, exchange constants, Fermi wave-vector, Mn–Mn interatomic distance). The transport properties were studied via the temperature dependence of electrical resistivity [ρ(T)], which shows a peak at Curie temperature due to metal to insulator transition. The percolation theory was used to simulate ρ(T) in both the ferromagnetic and paramagnetic phases. Reasonable agreement with the experimental data is reported. - Highlights: • The magnetic and transport properties of epitaxial La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films are investigated. • The M(T) curve was modeled at low temperature, and several magnetic parameters were obtained using spin wave theory. • The percolation theory was used to simulate ρ(T) in both the ferromagnetic and paramagnetic phases.

  17. Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO_{3}.

    Science.gov (United States)

    Kézsmárki, I; Nagel, U; Bordács, S; Fishman, R S; Lee, J H; Yi, Hee Taek; Cheong, S-W; Rõõm, T

    2015-09-18

    Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

  18. MODELING THE MULTI-BAND AFTERGLOW OF GRB 130831A: EVIDENCE FOR A SPINNING-DOWN MAGNETAR DOMINATED BY GRAVITATIONAL WAVE LOSSES?

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.; Zong, H. S. [School of Physics, Nanjing University, Nanjing 210093 (China); Huang, Y. F., E-mail: zonghs@nju.edu.cn, E-mail: hyf@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2016-06-01

    The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ∼0.8, followed by a steep drop at around 10{sup 5} s with a slope of ∼6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.

  19. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED ''SINGLE SPIN ASYMMETRIES'' (VOLUME 75)

    International Nuclear Information System (INIS)

    YUAN, F.; VOGELSANG, W.

    2005-01-01

    Single-transverse spin asymmetries (SSA) in strong interactions have a long history, starting from the 1970s and 1980s when surprisingly large single-transverse spin asymmetries were observed in p+p → πX and pp → Λ + X, where really none were expected. They have again attracted much interest in recent years from both experimental and theoretical sides. In particular, first measurements by the STAR, PHENIX, and BRAHMS collaborations at RHIC have now become available which again reveal large single transverse spin asymmetries for hadron production in polarized proton proton scattering. This extends the SSA observations from the fixed target energy range to the collider regime. Meanwhile, experimental studies in Deep Inelastic Scattering by the HERMES collaboration at DESY, SMC at CERN, and CLAS at JLab also show a remarkably large SSA in semi-inclusive hadron production, γ*p → πX, when the proton is transversely polarized. On the theoretical side, there are several approaches to understanding SSA within Quantum Chromodynamics (QCD). For example, to explain the large SSAs for hadron production in hadron collisions, a mechanism that takes into account the contribution from quark-gluon-quark correlations (twist-3) in the nucleon was proposed. On the other hand, possible origins of SSA in DIS and hadronic scattering were also found in leading-twist transverse momentum dependent parton distributions. Current theoretical efforts aim at a better conceptual understanding of these two types of mechanisms, and of their connections. We were very happy at this timely date to bring together the theorists and experimentalists of this field to review and discuss the current theoretical status and the latest experimental results. The whole workshop contained 25 formal talks, both experiment (15) and theory (10), and a few informal talks and many fruitful discussions. The topics covered all the relevant SSA observables, including in Deep Inelastic Scattering, the Drell

  20. Relativistic impulse approximation and deuteron spin structure

    International Nuclear Information System (INIS)

    Tokarev, M.V.

    1992-01-01

    The fragmentation processes were considered of tensor- and vector-polarized deuterons to protons in the framework of the covariant approach in the light cone variables on the basis of the relativistic deuteron wave function with one nucleon on-mass shell. The experimental verification of predicted dependences of T 20 and K is of interest for the research of the momentum and spin distributions of high momentum deuteron constituents. 21 refs.; 6 figs

  1. Leading research report for fiscal 1999. Fundamental technology of spin electronic device; 1999 nendo spin toronikusu soshi kiban gijutsu kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    The project, with attention paid to both spin and charge of electrons, aims to draw the best of the said two attributes of electrons by use of the state of the art in manufacturing technology for the creation of novel electronic devices. The nonvolatile MRAM (magnetic random access memory), which is the nearest to commercialization, is a tunnel device consisting of two sheet-shape ferromagnetic metal electrodes and an insulator film sandwiched between the said two electrodes, with the lower electrode magnetized only in one direction. The tunnel resistance changes when the magnetization direction in the upper electrode changes left and right (1, 0) according to an external writing magnetic field, and this enables nondestructive readout. The upper electrode magnetization direction remains unchanged thanks to hysteresis when the external writing magnetic field is turned off, and this allows the device to serve as a nonvolatile memory device. The device has a potential for higher speeds and enhanced integration. Much is also expected from a spin conduction functional device utilizing spin-dependent electric conduction, spin optical function device, spin quantum calculation directly utilizing quantum state, magnetic field sensor, etc. Their importance is great economically and socially, and technologies relating to magnetism and semiconductor should be merged for their further development. (NEDO)

  2. Semiclassical treatment of transport and spin relaxation in spin-orbit coupled systems

    Energy Technology Data Exchange (ETDEWEB)

    Lueffe, Matthias Clemens

    2012-02-10

    The coupling of orbital motion and spin, as derived from the relativistic Dirac equation, plays an important role not only in the atomic spectra but as well in solid state physics. Spin-orbit interactions are fundamental for the young research field of semiconductor spintronics, which is inspired by the idea to use the electron's spin instead of its charge for fast and power saving information processing in the future. However, on the route towards a functional spin transistor there is still some groundwork to be done, e.g., concerning the detailed understanding of spin relaxation in semiconductors. The first part of the present thesis can be placed in this context. We have investigated the processes contributing to the relaxation of a particularly long-lived spin-density wave, which can exist in semiconductor heterostructures with Dresselhaus and Rashba spin-orbit coupling of precisely the same magnitude. We have used a semiclassical spindiffusion equation to study the influence of the Coulomb interaction on the lifetime of this persistent spin helix. We have thus established that, in the presence of perturbations that violate the special symmetry of the problem, electron-electron scattering can have an impact on the relaxation of the spin helix. The resulting temperature-dependent lifetime reproduces the experimentally observed one in a satisfactory manner. It turns out that cubic Dresselhaus spin-orbit coupling is the most important symmetry-breaking element. The Coulomb interaction affects the dynamics of the persistent spin helix also via an Hartree-Fock exchange field. As a consequence, the individual spins precess about the vector of the surrounding local spin density, thus causing a nonlinear dynamics. We have shown that, for an experimentally accessible degree of initial spin polarization, characteristic non-linear effects such as a dramatic increase of lifetime and the appearance of higher harmonics can be expected. Another fascinating solid

  3. Effects of the competition between the exchange and dipolar interactions in the spin-wave spectrum of two-dimensional circularly magnetized nanodots

    International Nuclear Information System (INIS)

    Mamica, S; Krawczyk, M; Lévy, J-C S

    2014-01-01

    We use a microscopic theory taking into account the dipolar and nearest-neighbour exchange interactions for exploring spin-wave excitations in two-dimensional magnetic dots in the vortex state. Normal modes of different profiles are observed: azimuthal and radial modes, as well as fundamental (quasiuniform) and highly localized modes. We examine the dependence of the frequencies and profiles of these modes on the dipolar-to-exchange interaction ratio and the size of the dot. Special attention is paid to some particular modes, including the lowest mode in the spectrum and the evolution of its profile, and the fundamental mode, the frequency of which proves almost independent of the dipolar-to-exchange interaction ratio. We also provide a selective overview of the experimental, analytical and numerical results from the literature, where different profiles of the lowest mode are reported. We attribute this diversity to the competition between the dipolar and exchange interactions. Finally, we study the hybridization of the modes, show the multi-mode hybridization and explain the selection rules. (paper)

  4. Finite-temperature coupled-cluster, many-body perturbation, and restricted and unrestricted Hartree-Fock study on one-dimensional solids: Luttinger liquids, Peierls transitions, and spin- and charge-density waves.

    Science.gov (United States)

    Hermes, Matthew R; Hirata, So

    2015-09-14

    One-dimensional (1D) solids exhibit a number of striking electronic structures including charge-density wave (CDW) and spin-density wave (SDW). Also, the Peierls theorem states that at zero temperature, a 1D system predicted by simple band theory to be a metal will spontaneously dimerize and open a finite fundamental bandgap, while at higher temperatures, it will assume the equidistant geometry with zero bandgap (a Peierls transition). We computationally study these unique electronic structures and transition in polyyne and all-trans polyacetylene using finite-temperature generalizations of ab initio spin-unrestricted Hartree-Fock (UHF) and spin-restricted coupled-cluster doubles (CCD) theories, extending upon previous work [He et al., J. Chem. Phys. 140, 024702 (2014)] that is based on spin-restricted Hartree-Fock (RHF) and second-order many-body perturbation (MP2) theories. Unlike RHF, UHF can predict SDW as well as CDW and metallic states, and unlike MP2, CCD does not diverge even if the underlying RHF reference wave function is metallic. UHF predicts a gapped SDW state with no dimerization at low temperatures, which gradually becomes metallic as the temperature is raised. CCD, meanwhile, confirms that electron correlation lowers the Peierls transition temperature. Furthermore, we show that the results from all theories for both polymers are subject to a unified interpretation in terms of the UHF solutions to the Hubbard-Peierls model using different values of the electron-electron interaction strength, U/t, in its Hamiltonian. The CCD wave function is shown to encompass the form of the exact solution of the Tomonaga-Luttinger model and is thus expected to describe accurately the electronic structure of Luttinger liquids.

  5. High spin structure functions

    International Nuclear Information System (INIS)

    Khan, H.

    1990-01-01

    This thesis explores deep inelastic scattering of a lepton beam from a polarized nuclear target with spin J=1. After reviewing the formation for spin-1/2, the structure functions for a spin-1 target are defined in terms of the helicity amplitudes for forward compton scattering. A version of the convolution model, which incorporates relativistic and binding energy corrections is used to calculate the structure functions of a neutron target. A simple parameterization of these structure functions is given in terms of a few neutron wave function parameters and the free nucleon structure functions. This allows for an easy comparison of structure functions calculated using different neutron models. (author)

  6. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 65, RHIC SPIN COLLABORATION MEETINGS XXVII, XXVIII, and XXX

    International Nuclear Information System (INIS)

    OGAWA, A.

    2004-01-01

    The RIKEN BNL Research Center (RSRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the 'Rikagaku Kenkyusho' (RIKEN, The Institute of Physical and Chemical Research) of Japan. The Center is dedicated to the study of strong interactions, including spin physics, lattice QCD, and RHIC physics through the nurturing of a new generation of young physicists. The RBRC has both a theory and experimental component. At present the theoretical group has 4 Fellows and 3 Research Associates as well as 11 RHIC Physics/University Fellows (academic year 2003-2004). To date there are approximately 30 graduates from the program of which 13 have attained tenure positions at major institutions worldwide. The experimental group is smaller and has 2 Fellows and 3 RHIC Physics/University Fellows and 3 Research Associates, and historically 6 individuals have attained permanent positions. Beginning in 2001 a new RIKEN Spin Program (RSP) category was implemented at RBRC. These appointments are joint positions of RBRC and RIKEN and include the following positions in theory and experiment: RSP Researchers, RSP Research Associates, and Young Researchers, who are mentored by senior RBRC Scientists, A number of RIKEN Jr. Research Associates and Visiting Scientists also contribute to the physics program at the Center. RBRC has an active workshop program on strong interaction physics with each workshop focused on a specific physics problem. Each workshop speaker is encouraged to select a few of the most important transparencies from his or her presentation, accompanied by a page of explanation. This material is collected at the end of the workshop by the organizer to form proceedings, which can therefore be available within a short time. To date there are sixty nine proceedings volumes available. The construction of a 0.6 teraflops parallel processor, dedicated to lattice QCD, begun at the Center on February 19, 1998, was completed on August 28, 1998 and is still

  7. Research on definition of hard rock shear wave velocity of site for nuclear power plant

    International Nuclear Information System (INIS)

    Ding Zhenkun; Xia Zufeng

    2013-01-01

    Background: The definition of hard rock shear wave velocity is one of the most critical issues in the work of site selection. Purpose: To make a definition of hard rock site on which the model can be assumed as fixed-base condition, a series of research had been done. Several possible hard rock site soil models were developed. Methods: Shear wave velocity of hard rock had been assumed from 1100 m/s to 3200 m/s. For each case, free field analysis and soil structure analysis had been performed. And responses in soil and key nodes of structure were compared. Results: In free field analysis, responses of models that shear wave velocity below 2400 m/s decreased a lot. In SSI analysis, structure responses didn't change much when shear wave velocity was above 2400 m/s. Conclusions: 2400 m/s was the lowest shear wave velocity for hard rock site for fixed-base assumption. (authors)

  8. Meta-research matters: Meta-spin cycles, the blindness of bias, and rebuilding trust.

    Science.gov (United States)

    Bero, Lisa

    2018-04-01

    Meta-research is research about research. Meta-research may not be as click-worthy as a meta-pug-a pug dog dressed up in a pug costume-but it is crucial to understanding research. A particularly valuable contribution of meta-research is to identify biases in a body of evidence. Bias can occur in the design, conduct, or publication of research and is a systematic deviation from the truth in results or inferences. The findings of meta-research can tell us which evidence to trust and what must be done to improve future research. We should be using meta-research to provide the evidence base for implementing systemic changes to improve research, not for discrediting it.

  9. Some little-known facts and events from the history of gravitational wave research in Ukraine

    Science.gov (United States)

    Yatskiv, Ya. S.,; Vavilova, I. B.; Romanets, O. A.; Savchuk, V. S.

    2017-10-01

    The paper deals with the history of gravitational wave research in Ukraine and describes two little-known facts and events. The first one is concerning with a short period of Dr. Nathan Rosen's life in Kyiv and his scientific activity at the Institute of Physics of the Academy of Sciences of the UkrSSR in 1936-1938 years. At that time, he has published several papers, which promoted the first steps in the creation of modern theories in the fields of gravity and quantum physics. These papers, including "Plane-polarized waves in the General Theory of Relativity", have been issued in the "Ukrainian Physical Notes" ("Ukrainski Fizychni Zapysky"), which was not widely accessed. We quote also some parts from correspondence of N. Rosen and A. Einstein in this period. The second comment is related to the history of gravitational wave experimental research in Kyiv, which were initiated in 1970s by Prof. Aleksey Z. Petrov at the Institute of Theoretical Physics of the Academy of Sciences of the UkrSSR. We describe briefly the development of the detector of high-frequency gravitational waves (the Weber type antenna) as well as results obtained by K.A. Piragas's group.

  10. Symmetry-Breaking Orbital Anisotropy Observed for Detwinned Ba(Fe1-xCox)2As2 above the Spin Density Wave Transition

    International Nuclear Information System (INIS)

    Yi, Ming

    2011-01-01

    Nematicity, defined as broken rotational symmetry, has recently been observed in competing phases proximate to the superconducting phase in the cuprate high temperature superconductors. Similarly, the new iron-based high temperature superconductors exhibit a tetragonal to orthorhombic structural transition (i.e. a broken C 4 symmetry) that either precedes or is coincident with a collinear spin density wave (SDW) transition in undoped parent compounds, and superconductivity arises when both transitions are suppressed via doping. Evidence for strong in-plane anisotropy in the SDW state in this family of compounds has been reported by neutron scattering, scanning tunneling microscopy, and transport measurements. Here we present an angle resolved photoemission spectroscopy study of detwinned single crystals of a representative family of electron-doped iron-arsenide superconductors, Ba(Fe 1-x Co x ) 2 As 2 in the underdoped region. The crystals were detwinned via application of in-plane uniaxial stress, enabling measurements of single domain electronic structure in the orthorhombic state. At low temperatures, our results clearly demonstrate an in-plane electronic anisotropy characterized by a large energy splitting of two orthogonal bands with dominant d xz and d yz character, which is consistent with anisotropy observed by other probes. For compositions x > 0, for which the structural transition (T S ) precedes the magnetic transition (T SDW ), an anisotropic splitting is observed to develop above T SDW , indicating that it is specifically associated with T S . For unstressed crystals, the band splitting is observed close to T S , whereas for stressed crystals the splitting is observed to considerably higher temperatures, revealing the presence of a surprisingly large in-plane nematic susceptibility in the electronic structure.

  11. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON RHIC SPIN PHYSICS III AND IV, POLARIZED PARTONS AT HIGH Q2 REGION (VOLUME 31)

    International Nuclear Information System (INIS)

    BUNCE, G.; VIGDOR, S.

    2001-01-01

    International workshop on II Polarized Partons at High Q2 region 11 was held at the Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan on October 13-14, 2000, as a satellite of the international conference ''SPIN 2000'' (Osaka, Japan, October 16-21,2000). This workshop was supported by RIKEN (The Institute of Physical and Chemical Research) and by Yukawa Institute. The scientific program was focused on the upcoming polarized collider RHIC. The workshop was also an annual meeting of RHIC Spin Collaboration (RSC). The number of participants was 55, including 28 foreign visitors and 8 foreign-resident Japanese participants, reflecting the international nature of the RHIC spin program. At the workshop there were 25 oral presentations in four sessions, (1) RHIC Spin Commissioning, (2) Polarized Partons, Present and Future, (3) New Ideas on Polarization Phenomena, (4) Strategy for the Coming Spin Running. In (1) the successful polarized proton commissioning and the readiness of the accelerator for the physics program impressed us. In (2) and (3) active discussions were made on the new structure function to be firstly measured at RHIC, and several new theoretical ideas were presented. In session (4) we have established a plan for the beam time requirement toward the first collision of polarized protons. These proceedings include the transparencies presented at the workshop. The discussion on ''Strategy for the Coming Spin Running'' was summarized by the chairman of the session, S. Vigdor and G. Bunce

  12. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2012-01-01

    In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

  13. Topological phases in superconductor-noncollinear magnet interfaces with strong spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Menke, H.; Schnyder, A.P. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Toews, A. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Quantum Matter Institute, University of British Columbia, Vancouver, BC (Canada)

    2016-07-01

    Majorana fermions are predicted to emerge at interfaces between conventional s-wave superconductors and non-collinear magnets. In these heterostructures, the spin moments of the non-collinear magnet induce a low-energy band of Shiba bound states in the superconductor. Depending on the type of order of the magnet, the band structure of these bound states can be topologically nontrivial. Thus far, research has focused on systems where the influence of spin-orbit coupling can be neglected. Here, we explore the interplay between non-collinear (or non-coplanar) spin textures and Rashba-type spin-orbit interaction. This situation is realized, for example, in heterostructures between helical magnets and heavy elemental superconductors, such as Pb. Using a unitary transformation in spin space, we show that the effects of Rashba-type spin-orbit coupling are equivalent to the effects of the non-collinear spin texture of the helical magnet. We explore the topological phase diagram as a function of spin-orbit coupling, spin texture, and chemical potential, and find many interesting topological phases, such as p{sub x}-, (p{sub x} + p{sub y})-, and (p{sub x} + i p{sub y})-wave states. Conditions for the formation and the nature of Majorana edge channels are examined. Furthermore, we study the topological edge currents of these phases.

  14. Review of research in internal-wave and internal-tide deposits of China: Discussion

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2014-10-01

    Full Text Available This discussion of a review article by [27], published in the Journal of Palaeogeography (2(1: 56– 65, is aimed at illustrating that interpretations of ten ancient examples in China and one in the central Appalachians (USA as deep-water deposits of internal waves and internal tides are unsustainable. This critical assessment is based on an in-depth evaluation of oceanographic and sedimentologic data on internal waves and internal tides derived from 332 print and online published works during 1838–January 2013, which include empirical data on the physical characteristics of modern internal waves and internal tides from 51 regions of the world’s oceans [108]. In addition, core and outcrop descriptions of deep-water strata from 35 case studies worldwide carried out by the author during 1974–2011, and a selected number of case studies published by other researchers are evaluated for identifying the sedimentological challenges associated with distinguishing types of bottom-current reworked sands in the ancient sedimentary record. The emerging conclusion is that any interpretation of ancient strata as deposits of internal waves and internal tides is premature.

  15. The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures

    Science.gov (United States)

    Grollier, Julie

    2013-03-01

    Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.

  16. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  17. Geometrical spin symmetry and spin

    International Nuclear Information System (INIS)

    Pestov, I. B.

    2011-01-01

    Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

  18. NMR studies of spin dynamics in cuprates

    International Nuclear Information System (INIS)

    Takigawa, M.; Mitzi, D.B.

    1994-01-01

    The authors report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi 2.1 Sr 1.94 Ca 0.88 Cu 2.07 O 8+σ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa 2 Cu 3 O 6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector

  19. NMR studies of spin dynamics in cuprates

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-04-01

    We report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi2.1Sr1.94Ca0.88Cu2.07O8+δ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa2Cu3O6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector.

  20. Theory of unidirectional spin heat conveyer

    Science.gov (United States)

    Adachi, Hiroto; Maekawa, Sadamichi

    2015-05-01

    We theoretically investigate the unidirectional spin heat conveyer effect recently reported in the literature that emerges from the Damon-Eshbach spin wave on the surface of a magnetic material. We develop a simple phenomenological theory for heat transfer dynamics in a coupled system of phonons and the Damon-Eshbach spin wave, and demonstrate that there arises a direction-selective heat flow as a result of the competition between an isotropic heat diffusion by phonons and a unidirectional heat drift by the spin wave. The phenomenological approach can account for the asymmetric local temperature distribution observed in the experiment.

  1. OPTICS. Quantum spin Hall effect of light.

    Science.gov (United States)

    Bliokh, Konstantin Y; Smirnova, Daria; Nori, Franco

    2015-06-26

    Maxwell's equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell's theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces. Copyright © 2015, American Association for the Advancement of Science.

  2. Spin pumping and inverse spin Hall effects in heavy metal/antiferromagnet/Permalloy trilayers

    Science.gov (United States)

    Saglam, Hilal; Zhang, Wei; Jungfleisch, M. Benjamin; Jiang, Wanjun; Pearson, John E.; Hoffmann, Axel

    Recent work shows efficient spin transfer via spin waves in insulating antiferromagnets (AFMs), suggesting that AFMs can play a more active role in the manipulation of ferromagnets. We use spin pumping and inverse spin Hall effect experiments on heavy metal (Pt and W)/AFMs/Py (Ni80Fe20) trilayer structures, to examine the possible spin transfer phenomenon in metallic AFMs, i . e . , FeMn and PdMn. Previous work has studied electronic effects of the spin transport in these materials, yielding short spin diffusion length on the order of 1 nm. However, the work did not examine whether besides diffusive spin transport by the conduction electrons, there are additional spin transport contributions from spin wave excitations. We clearly observe spin transport from the Py spin reservoir to the heavy metal layer through the sandwiched AFMs with thicknesses well above the previously measured spin diffusion lengths, indicating that spin transport by spin waves may lead to non-negligible contributions This work was supported by US DOE, OS, Materials Sciences and Engineering Division. Lithographic patterning was carried out at the CNM, which is supported by DOE, OS under Contract No. DE-AC02-06CH11357.

  3. Physics lab in spin

    CERN Multimedia

    Hawkes, N

    1999-01-01

    RAL is fostering commerical exploitation of its research and facilities in two main ways : spin-out companies exploit work done at the lab, spin-in companies work on site taking advantage of the facilities and the expertise available (1/2 page).

  4. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  5. Observation of the spin Nernst effect

    Science.gov (United States)

    Meyer, S.; Chen, Y.-T.; Wimmer, S.; Althammer, M.; Wimmer, T.; Schlitz, R.; Geprägs, S.; Huebl, H.; Ködderitzsch, D.; Ebert, H.; Bauer, G. E. W.; Gross, R.; Goennenwein, S. T. B.

    2017-10-01

    The observation of the spin Hall effect triggered intense research on pure spin current transport. With the spin Hall effect, the spin Seebeck effect and the spin Peltier effect already observed, our picture of pure spin current transport is almost complete. The only missing piece is the spin Nernst (-Ettingshausen) effect, which so far has been discussed only on theoretical grounds. Here, we report the observation of the spin Nernst effect. By applying a longitudinal temperature gradient, we generate a pure transverse spin current in a Pt thin film. For readout, we exploit the magnetization-orientation-dependent spin transfer to an adjacent yttrium iron garnet layer, converting the spin Nernst current in Pt into a controlled change of the longitudinal and transverse thermopower voltage. Our experiments show that the spin Nernst and the spin Hall effect in Pt are of comparable magnitude, but differ in sign, as corroborated by first-principles calculations.

  6. Investigation of the temperature-dependence of ferromagnetic resonance and spin waves in Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Loong, Li Ming; Kwon, Jae Hyun; Deorani, Praveen; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore (Singapore); Tung Yu, Chris Nga [Department of Physics, The University of York, York YO10 5DD (United Kingdom); Hirohata, Atsufumi, E-mail: atsufumi.hirohata@york.ac.uk [Department of Electronics, The University of York, York YO10 5DD (United Kingdom)

    2014-06-09

    Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (CFAS) is a Heusler compound that is of interest for spintronics applications, due to its high spin polarization and relatively low Gilbert damping constant. In this study, the behavior of ferromagnetic resonance as a function of temperature was investigated in CFAS, yielding a decreasing trend of damping constant as the temperature was increased from 13 to 300 K. Furthermore, we studied spin waves in CFAS using both frequency domain and time domain techniques, obtaining group velocities and attenuation lengths as high as 26 km/s and 23.3 μm, respectively, at room temperature.

  7. Efficient Spin Injection into Semiconductor

    International Nuclear Information System (INIS)

    Nahid, M.A.I.

    2010-06-01

    Spintronic research has made tremendous progress nowadays for making future devices obtain extra advantages of low power, and faster and higher scalability compared to present electronic devices. A spintronic device is based on the transport of an electron's spin instead of charge. Efficient spin injection is one of the very important requirements for future spintronic devices. However, the effective spin injection is an exceedingly difficult task. In this paper, the importance of spin injection, basics of spin current and the essential requirements of spin injection are illustrated. The experimental technique of electrical spin injection into semiconductor is also discussed based on the experimental experience. The electrical spin injection can easily be implemented for spin injection into any semiconductor. (author)

  8. 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

  9. Topics in numerical relativity : the periodic standing-wave approximation, the stability of constraints in free evolution, and the spin of dynamical black holes

    Science.gov (United States)

    Owen, Robert

    This thesis concerns numerical relativity, the attempt to study Einstein's theory of gravitation using numerical discretization. The goal of the field, the study of gravitational dynamics in cases where symmetry reduction or perturbation theory are not possible, finally seems to be coming to fruition, at least for the archetypal problem of the inspiral and coalescence of binary black hole systems. This thesis presents three episodes that each bear some relationship to this story.Chapters 2 and 3 present previously published work in collaboration with Richard Price and others on the so-called periodic standing-wave (PSW) approximation for binary inspiral. The approximation is to balance outgoing radiation with incoming radiation, stabilizing the orbit and making the problem stationary in a rotating frame. Chapters 2 and 3 apply the method to the problem of co-orbiting charges coupled to a nonlinear scalar field in three dimensions.Chapters 4, 5, and 6 concern the stability of constraint fields in conventional numerical relativity simulations. Chapter 4 (also previously published work, in collaboration with the Caltech numerical relativity group, along with Michael Holst and Lawrence Kidder) presents a method for immediately correcting violations of constraints after they have arisen. Chapters 5 and 6 present methods to ``damp' away constraint violations dynamically in two specific contexts. Chapter 5 (previously published work in collaboration with the Caltech numerical relativity group and Lawrence Kidder) presents a first-order linearly degenerate symmetric hyperbolic representation of Einstein's equations in generalized harmonic gauge. A representation is presented that stabilizes all constraints, including those that appear when the system is written in first-order form. Chapter 6 presents a generalization of the Kidder-Scheel-Teukolsky evolution systems that provides much-improved stability. This is investigated with numerical simulations of a single black hole

  10. A new spin on research translation: the Boston Consensus Conference on Human Biomonitoring.

    Science.gov (United States)

    Nelson, Jessica W; Scammell, Madeleine Kangsen; Altman, Rebecca Gasior; Webster, Thomas F; Ozonoff, David M

    2009-04-01

    Translating research to make it more understandable and effective (research translation) has been declared a priority in environmental health but does not always include communication to the public or residents of communities affected by environmental hazards. Their unique perspectives are also commonly missing from discussions about science and technology policy. The consensus conference process, developed in Denmark, offers a way to address this gap. The Boston Consensus Conference on Human Biomonitoring, held in Boston, Massachusetts, in the fall of 2006, was designed to educate and elicit input from 15 Boston-area residents on the scientifically complex topic of human biomonitoring for environmental chemicals. This lay panel considered the many ethical, legal, and scientific issues surrounding biomonitoring and prepared a report expressing their views. The lay panel's findings provide a distinct and important voice on the expanding use of biomonitoring. In some cases, such as a call for opt-in reporting of biomonitoring results to study participants, they mirror recommendations raised elsewhere. Other conclusions have not been heard previously, including the recommendation that an individual's results should be statutorily exempted from the medical record unless permission is granted, and the opportunity to use biomonitoring data to stimulate green chemistry. The consensus conference model addresses both aspects of a broader conception of research translation: engaging the public in scientific questions, and bringing their unique perspectives to bear on public health research, practice, and policy. In this specific application, a lay panel's recommendations on biomonitoring surveillance, communication, and ethics have practical implications for the conduct of biomonitoring studies and surveillance programs.

  11. Spin spectrometer at the holified heavy-ion research facility and some planned experiments

    International Nuclear Information System (INIS)

    Sarantites, D.G.; Jaaskelainen, M.; Hood, J.T.; Woodward, R.; Barker, J.H.; Hensley, D.C.; Halbert, M.L.; Chan, Y.D.

    1980-01-01

    The 4π multidetector γ-ray spectrometer at the Holified Heavy-ion Research Facility (HHIRF) is described in some detail. The following important features of this spectrometer are discussed: (a) the geometric arrangement, (b) the actual performance of the individual detector elements, (c) the associated electronics and data acquisition system, and (d) the response of the system to input γ-cascades including the effect of crystal-to-crystal scattering and the response to neutrons. The first few experiments to be performed are briefly described

  12. Experimental Research of Machineless Energy Separation Effect Influenced by Shock Waves

    Directory of Open Access Journals (Sweden)

    S. S. Popovich

    2016-01-01

    Full Text Available The paper presents experimental research results of machineless energy separation effect with transversal ribs in supersonic channel. The energy separation effect assumes a physical division of the inlet flow into two or more flows, each having different stagnation temperature. Among well-known energy separation effects noted there are Ranque-Hilsch vortex tubes, Hartmann-Sprenger resonance tubes, pulsating tubes and some others.A working principle of device under study is based on thermal interaction between subsonic and supersonic gas flows through a heat-conducting division wall. This energy separation method was proposed by academician Leontiev and was patented in 1998. A number of references for PhD theses, articles, and conference proceedings devoted to the research of “Leontiev tube” have been mentioned in the paper. Efficiency factors for energy separation device performability have been analyzed in detail. The main attention was focused on the phenomenon of shock waves generation in supersonic channel of Leontiev tube.Experiment was carried out in the air prototype of energy separation device with supersonic flow Mach numbers 1.9 and 2.5, stagnation temperatures 40°С and 70°С, and for uni-flow and counter-flow air moving direction in subsonic and supersonic channels. Shock waves have been generated by means of circular ribs in supersonic channel of energy separation device. The research was carried out by means of infrared thermal imaging, thermocouples, total and static pressure probes, and modern National Insturments automation equipment. The work shows that shock waves have no negative influence on energy separation effect. A conclusion is made that unexpected shock wave generation in supersonic channel will not cause operability loss. It was gained that counter-flow regime is more efficient than uni-flow. Energy separation effect also appears to be higher with the rise of Mach number and flow initial stagnation temperature

  13. Entangled spin chain

    Science.gov (United States)

    Salberger, Olof; Korepin, Vladimir

    We introduce a new model of interacting spin 1/2. It describes interactions of three nearest neighbors. The Hamiltonian can be expressed in terms of Fredkin gates. The Fredkin gate (also known as the controlled swap gate) is a computational circuit suitable for reversible computing. Our construction generalizes the model presented by Peter Shor and Ramis Movassagh to half-integer spins. Our model can be solved by means of Catalan combinatorics in the form of random walks on the upper half plane of a square lattice (Dyck walks). Each Dyck path can be mapped on a wave function of spins. The ground state is an equally weighted superposition of Dyck walks (instead of Motzkin walks). We can also express it as a matrix product state. We further construct a model of interacting spins 3/2 and greater half-integer spins. The models with higher spins require coloring of Dyck walks. We construct a SU(k) symmetric model (where k is the number of colors). The leading term of the entanglement entropy is then proportional to the square root of the length of the lattice (like in the Shor-Movassagh model). The gap closes as a high power of the length of the lattice [5, 11].

  14. Progress Report on the GROWTH (GNSS Reflectometry for Ocean Waves, Tides, and Height) Research Project

    Science.gov (United States)

    Kitazawa, Y.; Ichikawa, K.; Akiyama, H.; Ebinuma, T.; Isoguchi, O.; Kimura, N.; Konda, M.; Kouguchi, N.; Tamura, H.; Tomita, H.; Yoshikawa, Y.; Waseda, T.

    2016-12-01

    Global Navigation Satellite Systems (GNSS), such as GPS is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to high precision using radio signals transmitted from satellites, GNSS reflectometry (GNSS-R) involves making measurements from the reflections from the Earth of navigation signals from GNSS satellites. Reflected signals from sea surface are considered that those are useful to observe sea state and sea surface height. We have started a research program for GNSS-R applications on oceanographic observations under the contract with MEXT (Ministry of Education Culture, Sports, Science and Technology, JAPAN) and launched a Japanese research consortium, GROWTH (GNSS Reflectometry for Ocean Waves, Tides, and Height). It is aiming to evaluate the capabilities of GNSS-R observations for oceanographic phenomena with different time scales, such as ocean waves (1/10 to tens of seconds), tides (one or half days), and sea surface dynamic height (a few days to years). In situ observations of ocean wave spectrum, wind speed vertical profile, and sea surface height will be quantitatively compared with equivalent estimates from simultaneous GNSS-R measurements. The GROWTH project will utilize different types of observation platforms; marine observation towers (about 20 m height), multi-copters (about 100 to 150 m height), and much higher-altitude CYGNSS data. Cross-platform data, together with in situ oceanographic observations, will be compared after adequate temporal averaging that accounts differences of the footprint sizes and temporal and spatial scales of oceanographic phenomena. This paper will provide overview of the GROWTH project, preliminary test results, obtained by the multi-sensor platform at observation towers, suggest actual footprint sizes and identification of swell. Preparation status of a ground station which will be supplied to receive CYGNSS data

  15. Comparison of Spin Wave Theory with Neutron Scattering Results for MnF{sub 2}; Comparaison entre la Theorie de l'Onde de Spin et les Resultats Obtenus par la Diffusion des Neutrons dans MnF{sub 2}; Sravnenie teorij spinovoj volny s rezul'tatami rasseyaniya nejtronov dlya MnF{sub 2}; Estudio Comparativo, en el MnF{sub 2}, de la Teoria Ondulatoria del Spin y de los Resultados de la Dispersion Neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Low, G. G. [Atomic Energy Research Establishment, Harwell, Berks (United Kingdom)

    1965-04-15

    Recent inelastic neutron scattering experiments carried out by Okazaki and Turberfield have provided a direct measure of spin wave dispersion in MnF{sub 2} both at 4.2 Degree-Sign K and at higher temperatures approaching the Neel point. The low temperature results taken together with other magnetic data allow the various exchange constants in MnF{sub 2} to be evaluated with some precision. Using these constants, the spin wave formalism for anti-ferromagnets described by Oguchi has been employed to predict theoretically the temperature dependence of the spin wave dispersion. No disposable parameters are involved and theoretical dispersion curves may be compared with the experimental results for higher temperatures as a test of the spin wave theory. The spin wave energies were evaluated numerically and integrations over the Brillouin zone were carried out, thus avoiding the use of some form of series expansion in temperature. Account was taken of dynamical interactions between pairs of spin waves but kinematical effects were neglected. Renormalization of the spin wave energies was performed. This is an important factor for T/T{sub N}{>=} Vulgar-Fraction-One-Half The agreement between theory and experiment is in fact remarkably good up to temperatures corresponding to about 90% of the Neel point. It would be dangerous to extrapolate this result to systems of lower spin as kinematical effects are likely to play a much greater part in such cases. For MnF{sub 2} where S= 5/2 a rough estimate suggests that kinematical effects will not be important until M/M{sub O}-20% and this occurs only within a degree or so of the Neel point. A brief discussion of the likely consequences of a biquadratic exchange term in MnF{sub 2} is given and it is concluded that, if present, such exchange is quite small. (author) [French] Des experiences recentes, executees par Okazaki et Turberfield au moyen de la diffusion inelastique des neutrons, ont fourni une mesure directe de la dispersion de

  16. Research of dynamical Characteristics of slow deformation Waves as Massif Responses on Explosions

    Science.gov (United States)

    Hachay, Olga; Khachay, Oleg; Shipeev, Oleg

    2013-04-01

    The research of massif state with use of approaches of open system theory [1-3] was developed for investigation the criterions of dissipation regimes for real rock massifs, which are under heavy man-caused influence. For realization of that research we used the data of seismic catalogue of Tashtagol mine. As a result of the analyze of that data we defined character morphology of phase trajectories of massif response, which was locally in time in a stable state: on the phase plane with coordinates released by the massif during the dynamic event energy E and lg(dE/dt) there is a local area as a ball of twisted trajectories and some not great bursts from that ball, which are not greater than 105 joules. In some time intervals that burst can be larger, than 105 joules, achieving 106 joules and yet 109 joules. [3]. Evidently there are two reciprocal depend processes: the energy accumulation in the attracted phase trajectories area and resonance fault of the accumulated energy. But after the fault the system returns again to the same attracted phase trajectories area. For analyzing of the thin structure of the chaotic area we decided to add the method of processing of the seismic monitoring data by new parameters. We shall consider each point of explosion as a source of seismic or deformation waves. Using the kinematic approach of seismic information processing we shall each point of the massif response use as a time point of the first arrival of the deformation wave for calculation of the wave velocity, because additionally we know the coordinates of the fixed response and the coordinates of explosion. The use of additional parameter-velocity of slow deformation wave propagation allowed us with use method of phase diagrams identify their hierarchic structure, which allow us to use that information for modeling and interpretation the propagation seismic and deformation waves in hierarchic structures. It is researched with use of that suggested processing method the thin

  17. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND.

    Energy Technology Data Exchange (ETDEWEB)

    BLAND, L.; BOER, D.; SAITO, N.; VOGELSANG, W.

    2001-05-14

    The much anticipated RHIC spin physics program will commence this fall when the first physics run with colliding beams of polarized protons is expected. More specifically, the planned year-1 RHIC-Spin measurements are (1) the double-spin asymmetry A{sub LL}{sup {pi}} in production of pions by collisions of longitudinally polarized protons (in order to obtain first information on the proton's spin-dependent gluon density, {Delta}g); (2) the transverse single-spin asymmetry A{sub N}{sup {pi}} for pion production. These two reactions provided part of the motivation for our workshop. On the first day there were informative talks on the specific plans of STAR (by Rakness) and PHENIX (by Goto) for the polarized run of Year-1. Some of the theoretical questions related to the double-spin asymmetry A{sub LL}{sup {pi}} were discussed on the first day by Vogelsang and Kretzer, which centered mostly around the questions of how well the unpolarized fragmentation functions are known, the need for next-to-leading order calculations, and on how sensitive the asymmetry is to the possible {Delta}g distributions. Vetterli presented HERMES measurements of fragmentation functions, which overlap in Q{sup 2} with the future lower-p{sub T} measurements at RHIC.

  18. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND

    International Nuclear Information System (INIS)

    BLAND, L.; BOER, D.; SAITO, N.; VOGELSANG, W.

    2001-01-01

    The much anticipated RHIC spin physics program will commence this fall when the first physics run with colliding beams of polarized protons is expected. More specifically, the planned year-1 RHIC-Spin measurements are (1) the double-spin asymmetry A LL π in production of pions by collisions of longitudinally polarized protons (in order to obtain first information on the proton's spin-dependent gluon density, Δg); (2) the transverse single-spin asymmetry A N π for pion production. These two reactions provided part of the motivation for our workshop. On the first day there were informative talks on the specific plans of STAR (by Rakness) and PHENIX (by Goto) for the polarized run of Year-1. Some of the theoretical questions related to the double-spin asymmetry A LL π were discussed on the first day by Vogelsang and Kretzer, which centered mostly around the questions of how well the unpolarized fragmentation functions are known, the need for next-to-leading order calculations, and on how sensitive the asymmetry is to the possible Δg distributions. Vetterli presented HERMES measurements of fragmentation functions, which overlap in Q 2 with the future lower-p T measurements at RHIC

  19. Spin-polarized free electron beam interaction with radiation and superradiant spin-flip radiative emission

    Directory of Open Access Journals (Sweden)

    A. Gover

    2006-06-01

    Full Text Available The problems of spin-polarized free-electron beam interaction with electromagnetic wave at electron-spin resonance conditions in a magnetic field and of superradiant spin-flip radiative emission are analyzed in the framework of a comprehensive classical model. The spontaneous emission of spin-flip radiation from electron beams is very weak. We show that the detectivity of electron spin resonant spin-flip and combined spin-flip/cyclotron-resonance-emission radiation can be substantially enhanced by operating with ultrashort spin-polarized electron beam bunches under conditions of superradiant (coherent emission. The proposed radiative spin-state modulation and the spin-flip radiative emission schemes can be used for control and noninvasive diagnostics of polarized electron/positron beams. Such schemes are of relevance in important scattering experiments off nucleons in nuclear physics and off magnetic targets in condensed matter physics.

  20. Ionosphere Waves Service (IWS – a problem-oriented tool in ionosphere and Space Weather research produced by POPDAT project

    Directory of Open Access Journals (Sweden)

    Ferencz Csaba

    2014-05-01

    Full Text Available In the frame of the FP7 POPDAT project the Ionosphere Waves Service (IWS has been developed and opened for public access by ionosphere experts. IWS is forming a database, derived from archived ionospheric wave records to assist the ionosphere and Space Weather research, and to answer the following questions: How can the data of earlier ionospheric missions be reprocessed with current algorithms to gain more profitable results? How could the scientific community be provided with a new insight on wave processes that take place in the ionosphere? The answer is a specific and unique data mining service accessing a collection of topical catalogs that characterize a huge number of recorded occurrences of Whistler-like Electromagnetic Wave Phenomena, Atmosphere Gravity Waves, and Traveling Ionosphere Disturbances. IWS online service (http://popdat.cbk.waw.pl offers end users to query optional set of predefined wave phenomena, their detailed characteristics. These were collected by target specific event detection algorithms in selected satellite records during database buildup phase. Result of performed wave processing thus represents useful information on statistical or comparative investigations of wave types, listed in a detailed catalog of ionospheric wave phenomena. The IWS provides wave event characteristics, extracted by specific software systems from data records of the selected satellite missions. The end-user can access targets by making specific searches and use statistical modules within the service in their field of interest. Therefore the IWS opens a new way in ionosphere and Space Weather research. The scientific applications covered by IWS concern beyond Space Weather also other fields like earthquake precursors, ionosphere climatology, geomagnetic storms, troposphere-ionosphere energy transfer, and trans-ionosphere link perturbations.

  1. Ionosphere Waves Service (IWS) - a problem-oriented tool in ionosphere and Space Weather research produced by POPDAT project

    Science.gov (United States)

    Ferencz, Csaba; Lizunov, Georgii; Crespon, François; Price, Ivan; Bankov, Ludmil; Przepiórka, Dorota; Brieß, Klaus; Dudkin, Denis; Girenko, Andrey; Korepanov, Valery; Kuzmych, Andrii; Skorokhod, Tetiana; Marinov, Pencho; Piankova, Olena; Rothkaehl, Hanna; Shtus, Tetyana; Steinbach, Péter; Lichtenberger, János; Sterenharz, Arnold; Vassileva, Any

    2014-05-01

    In the frame of the FP7 POPDAT project the Ionosphere Waves Service (IWS) has been developed and opened for public access by ionosphere experts. IWS is forming a database, derived from archived ionospheric wave records to assist the ionosphere and Space Weather research, and to answer the following questions: How can the data of earlier ionospheric missions be reprocessed with current algorithms to gain more profitable results? How could the scientific community be provided with a new insight on wave processes that take place in the ionosphere? The answer is a specific and unique data mining service accessing a collection of topical catalogs that characterize a huge number of recorded occurrences of Whistler-like Electromagnetic Wave Phenomena, Atmosphere Gravity Waves, and Traveling Ionosphere Disturbances. IWS online service (http://popdat.cbk.waw.pl) offers end users to query optional set of predefined wave phenomena, their detailed characteristics. These were collected by target specific event detection algorithms in selected satellite records during database buildup phase. Result of performed wave processing thus represents useful information on statistical or comparative investigations of wave types, listed in a detailed catalog of ionospheric wave phenomena. The IWS provides wave event characteristics, extracted by specific software systems from data records of the selected satellite missions. The end-user can access targets by making specific searches and use statistical modules within the service in their field of interest. Therefore the IWS opens a new way in ionosphere and Space Weather research. The scientific applications covered by IWS concern beyond Space Weather also other fields like earthquake precursors, ionosphere climatology, geomagnetic storms, troposphere-ionosphere energy transfer, and trans-ionosphere link perturbations.

  2. Superconducting quasiparticle lifetimes due to spin-fluctuation scattering

    International Nuclear Information System (INIS)

    Quinlan, S.M.; Scalapino, D.J.; Bulut, N.

    1994-01-01

    Superconducting quasiparticle lifetimes associated with spin-fluctuation scattering are calculated. A Berk-Schrieffer interaction with an irreducible susceptibility given by a BCS form is used to model the quasiparticle damping due to spin fluctuations. Results are presented for both s-wave and d-wave gaps. Also, quasiparticle lifetimes due to impurity scattering are calculated for a d-wave superconductor

  3. Quantum revivals and magnetization tunneling in effective spin systems

    International Nuclear Information System (INIS)

    Krizanac, M; Altwein, D; Vedmedenko, E Y; Wiesendanger, R

    2016-01-01

    Quantum mechanical objects or nano-objects have been proposed as bits for information storage. While time-averaged properties of magnetic, quantum-mechanical particles have been extensively studied experimentally and theoretically, experimental investigations of the real time evolution of magnetization in the quantum regime were not possible until recent developments in pump–probe techniques. Here we investigate the quantum dynamics of effective spin systems by means of analytical and numerical treatments. Particular attention is paid to the quantum revival time and its relation to the magnetization tunneling. The quantum revival time has been initially defined as the recurrence time of a total wave-function. Here we show that the quantum revivals of wave-functions and expectation values in spin systems may be quite different which gives rise to a more sophisticated definition of the quantum revival within the realm of experimental research. Particularly, the revival times for integer spins coincide which is not the case for half-integer spins. Furthermore, the quantum revival is found to be shortest for integer ratios between the on-site anisotropy and an external magnetic field paving the way to novel methods of anisotropy measurements. We show that the quantum tunneling of magnetization at avoided level crossing is coherent to the quantum revival time of expectation values, leading to a connection between these two fundamental properties of quantum mechanical spins. (paper)

  4. Spin-Triplet Pairing Induced by Spin-Singlet Interactions in Noncentrosymmetric Superconductors

    Science.gov (United States)

    Matsuzaki, Tomoaki; Shimahara, Hiroshi

    2017-02-01

    In noncentrosymmetric superconductors, we examine the effect of the difference between the intraband and interband interactions, which becomes more important when the band splitting increases. We define the difference ΔVμ between their coupling constants, i.e., that between the intraband and interband hopping energies of intraband Cooper pairs. Here, the subscript μ of ΔVμ indicates that the interactions scatter the spin-singlet and spin-triplet pairs when μ = 0 and μ = 1,2,3, respectively. It is shown that the strong antisymmetric spin-orbit interaction reverses the target spin parity of the interaction: it converts the spin-singlet and spin-triplet interactions represented by ΔV0 and ΔVμ>0 into effective spin-triplet and spin-singlet pairing interactions, respectively. Hence, for example, triplet pairing can be induced solely by the singlet interaction ΔV0. We name the pairing symmetry of the system after that of the intraband Cooper pair wave function, but with an odd-parity phase factor excluded. The pairing symmetry must then be even, even for the triplet component, and the following results are obtained. When ΔVμ is small, the spin-triplet p-wave interactions induce spin-triplet s-wave and spin-triplet d-wave pairings in the regions where the repulsive singlet s-wave interaction is weak and strong, respectively. When ΔV0 is large, a repulsive interband spin-singlet interaction can stabilize spin-triplet pairing. When the Rashba interaction is adopted for the spin-orbit interaction, the spin-triplet pairing interactions mediated by transverse magnetic fluctuations do not contribute to triplet pairing.

  5. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2017-01-01

    Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

  6. Frustrated spin systems

    CERN Document Server

    2013-01-01

    This book covers all principal aspects of currently investigated frustrated systems, from exactly solved frustrated models to real experimental frustrated systems, going through renormalization group treatment, Monte Carlo investigation of frustrated classical Ising and vector spin models, low-dimensional systems, spin ice and quantum spin glass. The reader can - within a single book - obtain a global view of the current research development in the field of frustrated systems.This new edition is updated with recent theoretical, numerical and experimental developments in the field of frustrated

  7. Spin Hall effect transistor

    Czech Academy of Sciences Publication Activity Database

    Wunderlich, Joerg; Park, B.G.; Irvine, A.C.; Zarbo, Liviu; Rozkotová, E.; Němec, P.; Novák, Vít; Sinova, Jairo; Jungwirth, Tomáš

    2010-01-01

    Roč. 330, č. 6012 (2010), s. 1801-1804 ISSN 0036-8075 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 31.364, year: 2010

  8. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  9. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  10. Spin correlations in quantum wires

    Science.gov (United States)

    Sun, Chen; Pokrovsky, Valery L.

    2015-04-01

    We consider theoretically spin correlations in a one-dimensional quantum wire with Rashba-Dresselhaus spin-orbit interaction (RDI). The correlations of noninteracting electrons display electron spin resonance at a frequency proportional to the RDI coupling. Interacting electrons, upon varying the direction of the external magnetic field, transit from the state of Luttinger liquid (LL) to the spin-density wave (SDW) state. We show that the two-time total-spin correlations of these states are significantly different. In the LL, the projection of total spin to the direction of the RDI-induced field is conserved and the corresponding correlator is equal to zero. The correlators of two components perpendicular to the RDI field display a sharp electron-spin resonance driven by the RDI-induced intrinsic field. In contrast, in the SDW state, the longitudinal projection of spin dominates, whereas the transverse components are suppressed. This prediction indicates a simple way for an experimental diagnostic of the SDW in a quantum wire. We point out that the Luttinger model does not respect the spin conservation since it assumes the infinite Fermi sea. We propose a proper cutoff to correct this failure.

  11. On the concept of spin

    International Nuclear Information System (INIS)

    Pestov, I.B.

    1997-01-01

    It is substantiated that spin is a notion associated with the group of internal symmetry that is tightly connected with the geometrical structure of spacetime. The wave equation for the description of a particle with spin one half is proposed. On this ground it is shown that the spin of electron is exhibited through the quantum number and accordingly the Dirac equation describes properties of particles with the projection of spin ±h/2. On the contrary, we put forward the conjecture that the spin of the quark cannot be considered as a quantum number, but only as an origin of a non-abelian gauge field. The reason is that the quark and electron from physical, geometrical and group-theoretical points of view differ from each other. It is a deep reason for understanding quark-lepton symmetry and such important phenomena as quark confinement

  12. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies, co...

  13. Spin 1990

    International Nuclear Information System (INIS)

    Anton, Gisela

    1990-01-01

    The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

  14. Spin 1990

    Energy Technology Data Exchange (ETDEWEB)

    Anton, Gisela

    1990-12-15

    The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

  15. Spin tomography

    Energy Technology Data Exchange (ETDEWEB)

    D' Ariano, G M [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy); Maccone, L [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy); Paini, M [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy)

    2003-02-01

    We propose a tomographic reconstruction scheme for spin states. The experimental set-up, which is a modification of the Stern-Gerlach scheme, can be easily performed with currently available technology. The method is generalized to multiparticle states, analysing the spin-1/2 case for indistinguishable particles. Some Monte Carlo numerical simulations are given to illustrate the technique.

  16. Spin tomography

    International Nuclear Information System (INIS)

    D'Ariano, G M; Maccone, L; Paini, M

    2003-01-01

    We propose a tomographic reconstruction scheme for spin states. The experimental set-up, which is a modification of the Stern-Gerlach scheme, can be easily performed with currently available technology. The method is generalized to multiparticle states, analysing the spin-1/2 case for indistinguishable particles. Some Monte Carlo numerical simulations are given to illustrate the technique

  17. TRENDS IN THE DEVELOPMENT OF DETONATION ENGINES FOR HIGH-SPEED AEROSPACE AIRCRAFTS AND THE PROBLEM OF TRIPLE CONFIGURATIONS OF SHOCK WAVES. Part II - Research of counterpropagating shock waves and triple shock wave configurations

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2016-03-01

    Full Text Available The paper deals with current issues of the interference theory development of gas-dynamic discontinuities as applied to a problem of propulsion refinement for the air-spacecrafts, designed for hypersonic flight speeds. In the first part of the review we have presented the history of detonation study and different concepts of detonation engines, as well as air intakes designed for hypersonic flight speeds. The second part provides an overview of works on the interference theory development for gas-dynamic discontinuities. We report about classification of the gas-dynamic discontinuities, shock wave propagation, shock-wave structures and triple configurations of shock waves. We have shown that many of these processes are accompanied by a hysteresis phenomenon, there are areas of ambiguity; therefore, in the design of engines and air intakes optimal shock-wave structures should be provided and their sustainability should be ensured. Much attention has recently been given to the use of the air intakes in the shock-wave structures with the rereflection of shock waves and the interference of shock waves in the opposite directions. This review provides increased focus on it, contains references to landmark works, the last calculated and experimental results. Unfortunately, foreign surveys missed many landmark works of the Soviet and Russian researchers, as they were not published in English. At the same time, it was the Soviet school of gas dynamics that has formulated the interference theory of gas-dynamic discontinuities in its present form. To fill this gap is one of this review scopes. The review may be recommended for professionals, engineers and scientists working in the field of aerospace engineering.

  18. Spin symposium

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1989-01-15

    The recent 8th International Symposium on High Energy Spin Physics at the University of Minnesota in Minneapolis, Minnesota, opened with a bang when L. Pondrom (Wisconsin), donning a hard hat borrowed from construction workers, ventured that 'spin, the notorious inessential complication of hadronic physics, is finally telling us what real QCD (quantum chromodynamics, the field theory of quarks and gluons) looks like.' He was referring to an animated discussion on the meaning of the recent spin oriented (polarized) scattering results from the European Muon Collaboration (EMC) at CERN and reported at the Symposium by R. Garnet (Liverpool) and P. Schuler (Yale) which show that the proton spin is not simply a reflection of the spins of its constituent quarks.

  19. Nanopatterning spin-textures: A route to reconfigurable magnonics

    Directory of Open Access Journals (Sweden)

    E. Albisetti

    2017-05-01

    Full Text Available Magnonics is envisioned to enable highly efficient data transport and processing, by exploiting propagating perturbations in the spin-texture of magnetic materials. Despite the demonstrations of a plethora of proof-of-principle devices, the efficient excitation, transport and manipulation of spin-waves at the nanoscale is still an open challenge. Recently, we demonstrated that the spin-wave excitation and propagation can be controlled by nanopatterning reconfigurable spin-textures in a continuous exchange biased ferromagnetic film. Here, we show that by patterning 90° stripe-shaped magnetic domains, we spatially modulate the spin-wave excitation in a continuous film, and that by applying an external magnetic field we can reversibly “switch-off” the spin-wave excitation. This opens the way to the use of nanopatterned spin-textures, such as domains and domain walls, for exciting and manipulating magnons in reconfigurable nanocircuits.

  20. Collaborative research: Dynamics of electrostatic solitary waves and their effects on current layers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Li-Jen

    2014-04-18

    The project has accomplished the following achievements including the goals outlined in the original proposal. Generation and measurements of Debye-scale electron holes in laboratory: We have generated by beam injections electron solitary waves in the LAPD experiments. The measurements were made possible by the fabrication of the state-of-the-art microprobes at UCLA to measure Debye-scale electric fields [Chiang et al., 2011]. We obtained a result that challenged the state of knowledge about electron hole generation. We found that the electron holes were not due to two-stream instability, but generated by a current-driven instability that also generated whistler-mode waves [Lefebvre et al., 2011, 2010b]. Most of the grant supported a young research scientist Bertrand Lefebvre who led the dissemination of the laboratory experimental results. In addition to two publications, our work relevant to the laboratory experiments on electron holes has resulted in 7 invited talks [Chen, 2007, 2009; Pickett et al., 2009a; Lefebvre et al., 2010a; Pickett et al., 2010; Chen et al., 2011c, b] (including those given by the co-I Jolene Pickett) and 2 contributed talks [Lefebvre et al., 2009b, a]. Discovery of elecctron phase-space-hole structure in the reconnection electron layer: Our theoretical analyses and simulations under this project led to the discovery of an inversion electric field layer whose phase-space signature is an electron hole within the electron diffusion layer in 2D anti-parallel reconnection [Chen et al., 2011a]. We carried out particle tracing studies to understand the electron orbits that result in the phase-space hole structure. Most importantly, we showed that the current density in the electron layer is limited in collisionless reconnection with negligible guide field by the cyclotron turning of meandering electrons. Comparison of electrostatic solitary waves in current layers observed by Cluster and in LAPD: We compared the ESWs observed in a supersubstorm