WorldWideScience

Sample records for anomalous magnetic properties

  1. Anomalous magnetic properties of VOx multiwall nanotubes

    Science.gov (United States)

    Demishev, S. V.; Chernobrovkin, A. L.; Glushkov, V. V.; Goodilin, E. A.; Grigorieva, A. V.; Ishchenko, T. V.; Kuznetsov, A. V.; Sluchanko, N. E.; Tretyakov, Yu D.; Semeno, A. V.

    2010-01-01

    Basing on the high frequency (60 GHz) electron spin resonance (ESR) and magnetic susceptibility study of the VOx multiwall nanotubes (VOx-NTs) in the range 4.2-300 K we report the ESR evidence of the presence of the antiferromagnetic V4+ dimers in VOx-NTs and the observation of an anomalous low temperature (T<50 K) growth of the magnetic susceptibility for V4+ quasi-free spins, which obey power law χ(T)~1/Tα with the exponent αapprox0.6. The estimates of the concentrations for various spin species (clusters) indicate that the non-interacting dimers should be an essential element in the VOx-NTs structure. The possibility of the disorder driven quantum critical regime in VOx-NTs is discussed.

  2. Anomalous increase in the magnetorheological properties of magnetic fluid induced by silica nanoparticles

    Science.gov (United States)

    Desai, Rucha; Upadhyay, R. V.

    2014-12-01

    Magnetorheological properties are experimentally investigated in aqueous magnetic fluid containing spherical silica nanoparticles. A bi-dispersed system is prepared using aqueous suspension of silica nanoparticles and aqueous magnetic fluid. Both these fluids exhibit Newtonian viscosity with nominal values of 1.3 and 5.8 mPa\\cdot s at 20 °C. Three different samples are prepared by varying silica and magnetic fluid concentrations and keeping the total volume constant. The addition of silica nanoparticles leads to enhancement of the magnetic field induced viscosity up to the order 107 Pa\\cdot s. The magnetic field induced viscosity is analyzed using the structural viscosity model. Magnetic field induced static and dynamic yield stress values to reveal the existence of field induced clustering. An attempt is made to explain this yielding behavior using chain-like and micromechanical models. It is found that high silica fraction leads to the formation of chain-like structure. At low silica fraction, chains overlap and result into layer aggregates, which are responsible for the anomalous increase in the magnetorheological properties. This is further confirmed using magnetic field microscopic chain formations.

  3. ANOMALOUS ELECTRODEPOSITION OF Fe-Ni ALLOY COATING FROM SIMPLE AND COMPLEX BATHS AND ITS MAGNETIC PROPERTY

    Directory of Open Access Journals (Sweden)

    M A Islam

    2010-03-01

    Full Text Available Electrodeposition of Fe-Ni thin films has been carried on copper substrate under various electrodeposition conditions from two simple and six complex baths. Sulfate baths composing of NiSO4. 7H2O, FeSO4.7H2O, H3BO3 and Na2SO4KEYWORDS: Anomalous Electrodeposition, Fe-Ni Coating, Complexing agent, Current Density, Magnetic Property. 1. INTRODUCTION Alloy electrodeposition technologies can extend tremendously the potential of electrochemical deposition processes to provide coatings that require unique mechanical, chemical and physical properties [1]. There has been a great research interest in the development and characterization of iron-nickel (Fe-Ni thin films due to their operational capacity, economic interest, magnetic and other properties [2]. Due to their unique low coefficient of thermal expansion (CTE and soft magnetic properties, Fe-Ni alloys have been used in industrial applications for over 100 years [3]. Typical examples of applications that are based on the low CTE of Fe-Ni alloys include: thermostatic bimetals, glass sealing, integrated circuit packaging, cathode ray tube, shadow masks, membranes for liquid natural gas tankers; applications based on the soft magnetic properties include: read-write heads for magnetic storage, magnetic actuators, magnetic shielding, high performance transformer cores. comprise the simple baths whereas complex baths were prepared by adding ascorbic acid, saccharin and citric acid in simple baths. The effect of bath composition, pH and applied current density on coating appearance, composition, morphology and magnetic property were studied. Wet chemical analysis technique was used to analyze the coating composition whereas SEM and VSM were used to study the deposit morphology and magnetic property respectively. Addition of complexing agents in plating baths suppressed the anomalous nature of Fe-Ni alloy electrodeposition. Coatings obtained from simple baths were characterized by coarse grained non

  4. ANOMALOUS ELECTRODEPOSITION OF Fe-Ni ALLOY COATING FROM SIMPLE AND COMPLEX BATHS AND ITS MAGNETIC PROPERTY

    OpenAIRE

    M A Islam

    2010-01-01

    Electrodeposition of Fe-Ni thin films has been carried on copper substrate under various electrodeposition conditions from two simple and six complex baths. Sulfate baths composing of NiSO4. 7H2O, FeSO4.7H2O, H3BO3 and Na2SO4KEYWORDS: Anomalous Electrodeposition, Fe-Ni Coating, Complexing agent, Current Density, Magnetic Property. 1. INTRODUCTION Alloy electrodeposition technologies can extend tremendously the potential of electrochemical deposition processes to provide coatings that require ...

  5. Magnetic and anomalous electronic transport properties of the quaternary Heusler alloys Co2Ti1-xFexGe

    Science.gov (United States)

    Venkateswarlu, B.; Midhunlal, P. V.; Babu, P. D.; Kumar, N. Harish

    2016-06-01

    The half-metallic Heusler alloy Co2TiGe has a ferromagnetic ground state with a low magnetic moment (2 μB). It is free of atomic antisite disorder but has low Curie temperature (~390 K). In contrast the other cobalt based Heusler alloy Co2FeGe has high Curie temperature (~980 K) and high magnetic moment (5.6 μB) while exhibiting antisite disorder and lack of half-metallicity. Hence it is of interest to investigate the magnetic and transport properties of solid solutions of these two materials with contrasting characteristics. We report the structural, magnetic and electronic transport properties of quaternary Co2Ti1-x FexGe (x=0.2, 0.4, 0.6, 0.8) Heusler alloys. The alloys crystallize in L21 structure but with antisite disorder. The magnetization measurements revealed that the alloys were of soft ferromagnetic type with high Curie temperatures. Deviation from Slater-Pauling behavior and drastic change in electronic transport properties with some anomalous features were observed.The complex electronic transport properties have been explained using different scattering mechanisms.

  6. Anomalous magnetic moment of anyons

    CERN Document Server

    Gat, G; Gat, Gil; Ray, Rashmi

    1994-01-01

    The anomalous magnetic moment of anyons is calculated to leading order in a 1/N expansion. It is shown that the gyromagnetic ratio g remains 2 to the leading order in 1/N. This result strongly supports that obtained in \\cite{poly}, namely that g=2 is in fact exact.

  7. Minimal muon anomalous magnetic moment

    CERN Document Server

    Biggio, Carla

    2014-01-01

    We classify all possible one-particle (scalar and fermion) extensions of the Standard Model that can contribute to the anomalous magnetic moment of leptons. We review the cases already discussed in the literature and complete the picture by performing the calculation for a fermionic doublet with hypercharge -3/2. We conclude that, out of the listed possibilities, only two scalar leptoquarks and the pseudoscalar of a peculiar two-Higgs-doublet model could be the responsibles for the muon anomalous magnetic moment discrepancy. Were this the case, this particles could be seen in the next LHC run. To this aim, especially to test the leptoquark hypothesis, we suggest to look for final states with tops and muons.

  8. A Mössbauer effect study, as the main key to the investigation of anomalous magnetic properties of MnZn nanoferrite

    Directory of Open Access Journals (Sweden)

    V Sepelak

    2012-12-01

    Full Text Available   In this research, a low temperature in-field 57Fe Mössbauer spectroscopy is used for investigation of anomalous magnetic properties of MnZn nanoferrite. Based on Mössbauer spectroscopy results, the reduced saturation magnetization of MnZn nanoferrite in respect to that of bulk sample is due to nonequilibrium cation distribution and spin disorder. The enhanced Curie temperature of MnZn nanoferrite in respect to that of bulk sample can be attributed to the strengthening of the (A-O-[B] superexchange interactions due to an increase of the magnetic ion concentration in the (A site.

  9. Anomalous magnetic moment with heavy virtual leptons

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Liu, Tao; Steinhauser, Matthias [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2013-11-15

    We compute the contributions to the electron and muon anomalous magnetic moment induced by heavy leptons up to four-loop order. Asymptotic expansion is applied to obtain three analytic expansion terms which show rapid convergence.

  10. Nanodomain induced anomalous magnetic and electronic transport properties of LaBaCo2O5.5+δ highly epitaxial thin films

    International Nuclear Information System (INIS)

    A giant magnetoresistance effect (∼46% at 20 K under 7 T) and anomalous magnetic properties were found in a highly epitaxial double perovskite LaBaCo2O5.5+δ (LBCO) thin film on (001) MgO. Aberration-corrected Electron Microscopy and related analytical techniques were employed to understand the nature of these unusual physical properties. The as-grown film is epitaxial with the c-axis of the LBCO structure lying in the film plane and with an interface relationship given by (100)LBCO || (001)MgO and [001]LBCO || [100]MgO or [010]MgO. Orderly oxygen vacancies were observed by line profile electron energy loss spectroscopy and by atomic resolution imaging. Especially, oxygen vacancy and nanodomain structures were found to have a crucial effect on the electronic transport and magnetic properties

  11. Theory of the Muon Anomalous Magnetic Moment

    CERN Document Server

    Melnikov, Kirill

    2006-01-01

    The theory of the muon anomalous magnetic moment is "particle physics in a nutshell" and as such is interesting, exciting and difficult. The current precision of the experimental value for this quantity, improved significantly in the past several years due to experiment E821 at Brookhaven National Laboratory, is so high that a large number of subtle effects not relevant previously, become important for the interpretation of the experimental result. The theory of the muon anomalous magnetic moment is at the cutting edge of current research in particle physics and includes multiloop calculations in both QED and electroweak theory, precision low-energy hadron physics, isospin violations and scattering of light by light. Any deviation between the theoretical prediction and the experimental value might be interpreted as a signal of an as-yet-unknown new physics. This book provides a comprehensive review of the theory of the muon anomalous magnetic moment.

  12. On the photon anomalous magnetic moment

    CERN Document Server

    Villalba, S; Villalba, Selym; Rojas, Hugo Perez

    2006-01-01

    It is shown that due to radiative corrections a photon having a non vanishing component of its momentum perpendicular to it, bears a non-zero magnetic moment. All modes of propagation of the polarization operator in one loop approximation are discussed and in this field regime the dispersion equation and the corresponding magnetic moment are derived. Near the first thresholds of cyclotron resonance the photon magnetic moment has a peak larger than the electron anomalous magnetic moment. Related to this magnetic moment, the arising of some sort of photon "dynamical mass" and a gyromagnetic ratio are discussed. These latter results might be interesting in an astrophysical context.

  13. The Anomalous Magnetic Moment of the Muon

    CERN Document Server

    Jegerlehner, Friedrich

    2008-01-01

    This book reviews the present state of knowledge of the anomalous magnetic moment a=(g-2)/2 of the muon. The muon anomalous magnetic moment amy is one of the most precisely measured quantities in elementary particle physics and provides one of the most stringent tests of relativistic quantum field theory as a fundamental theoretical framework. It allows for an extremely precise check of the standard model of elementary particles and of its limitations. Recent experiments at the Brookhaven National Laboratory now reach the unbelievable precision of 0.5 parts per million, improving the accuracy of previous g-2 experiments at CERN by a factor of 14. A major part of the book is devoted to the theory of the anomalous magnetic moment and to estimates of the theoretical uncertainties. Quantum electrodynamics and electroweak and hadronic effects are reviewed. Since non-perturbative hadronic effects play a key role for the precision test, their evaluation is described in detail. After the overview of theory, the exper...

  14. Anomalous magnetoresistance in magnetized topological insulator cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Siu, Zhuo Bin, E-mail: a0018876@nus.edu.sg [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Data Storage Institute, Agency for Science, Technology and Research, Singapore 117608 (Singapore); Jalil, Mansoor B. A. [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore)

    2015-05-07

    The close coupling between the spin and momentum degrees of freedom in topological insulators (TIs) presents the opportunity for the control of one to manipulate the other. The momentum can, for example, be confined on a curved surface and the spin influenced by applying a magnetic field. In this work, we study the surface states of a cylindrical TI magnetized in the x direction perpendicular to the cylindrical axis lying along the z direction. We show that a large magnetization leads to an upwards bending of the energy bands at small |k{sub z}|. The bending leads to an anomalous magnetoresistance where the transmission between two cylinders magnetized in opposite directions is higher than when the cylinders are magnetized at intermediate angles with respect to each other.

  15. Anomalous Josephson Hall effect in magnet/triplet superconductor junctions

    OpenAIRE

    Yokoyama, Takehito

    2015-01-01

    We investigate anomalous Hall effect in a magnet coupled to a triplet superconductor under phase gradient. It is found that the anomalous Hall supercurrent arises from non-trivial structure of the magnetization. The magnetic structure manifested in the Hall supercurrent is characterized by even order terms of the exchange coupling, essentially different from that discussed in the context of anomalous Hall effect, reflecting the disspationless nature of supercurrent. We also discuss a possible...

  16. Spectral Properties of Anomalous X-ray Pulsars

    Institute of Scientific and Technical Information of China (English)

    Ye Lu; Wei Wang; Yong-Heng Zhao

    2003-01-01

    We examine the spectra of the persistent emission from anomalous X-ray pulsars (AXPs) and their variation with the spin-down rate Ω. Based on an accretion-powered model, the influences of both the magnetic field and the mass accretion rate on the spectral properties of AXPs are addressed. We then investigate the relation between the spectral property of AXPs and mass accretion rate M. The result shows that there exists a linear correlation between the photon index and the mass accretion rate: the spectral hardness increases with increasing M. A possible emission mechanism for the explanation of the spectral properties of AXPs is also discussed.

  17. Anomalous transport effects in magnetically-confined plasma columns

    International Nuclear Information System (INIS)

    The evolution of density structure in a magnetized plasma column is analyzed accounting for anomalous diffusion due to the lower hybrid drift instability. The plasma column is found to be divided into regions of classical, anomalous, and intermediate diffusivity. The bulk behavior, described in terms of radial confinement time, depends most sensitively upon the particle line density (ion/cm). For broad plasmas (large line density), the transport is characteristic of classical diffusion, and for slender plasmas (small line density) the transport is characteristic of anomalous diffusion. For intermediate line densities, the transport undertakes a rapid transition from classical to anomalous. Correlations between the theoretical results and past experiments are described

  18. Anomalous hysteresis properties of iron films deposited on liquid surfaces

    Science.gov (United States)

    Ye, Quan-Lin; Feng, Chun-Mu; Xu, Xiao-Jun; Jin, Jin-Sheng; Xia, A.-Gen; Ye, Gao-Xiang

    2005-07-01

    A nearly free sustained iron film system, deposited on silicone oil surfaces by vapor-phase deposition method, has been fabricated and its crystal structure as well as magnetic properties has been studied. Both the temperature-dependent coercivity Hc(T) and exchange anisotropy field HE(T) of the iron films possess a maximum peak around the critical temperature Tcrit=10-15 and 4K, respectively. Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase below freezing temperature Tf=30-50K.

  19. Quantization of Spinning Particle with Anomalous Magnetic Momentum

    OpenAIRE

    Gitman, D. M.; Saa, A. V.

    1992-01-01

    A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic moment is given. The leading considerations, to write the action, are gotten from the path integral representation for the causal Green's function of the generalized (by Pauli) Dirac equation for the particle with anomalous magnetic momentum in an external electromagnetic field. The action can be written in reparametrization and supergauge invariant form. Both operator (Dirac) and pa...

  20. Magnetic Topological Insulators and Quantum Anomalous Hall Effect

    Science.gov (United States)

    Kou, Xufeng

    The engineering of topological surface states is a key to realize applicable devices based on topological insulators (TIs). Among various proposals, introducing magnetic impurities into TIs has been proven to be an effective way to open a surface gap and integrate additional ferromagnetism with the original topological order. In this Dissertation, we study both the intrinsic electrical and magnetic properties of the magnetic TI thin films grown by molecular beam epitaxy. By doping transition element Cr into the host tetradymite-type V-VI semiconductors, we achieve robust ferromagnetic order with a strong perpendicular magnetic anisotropy. With additional top-gating capability, we realize the electric-field-controlled ferromagnetism in the magnetic TI systems, and demonstrate such magneto-electric effects can be effectively manipulated, depending on the interplays between the band topology, magnetic exchange coupling, and structural engineering. Most significantly, we report the observation of quantum anomalous Hall effect (QAHE) in the Cr-doped (BiSb)2Te3 samples where dissipationless chiral edge conduction is realized in the macroscopic millimeter-size devices without the presence of any external magnetic field, and the stability of the quantized Hall conductance of e2/h is well-maintained as the film thickness varies across the 2D hybridization limit. With additional quantum confinement, we discover the metal-to-insulator switching between two opposite QAHE states, and reveal the universal QAHE phase diagram in the thin magnetic TI samples. In addition to the uniform magnetic TIs, we further investigate the TI/Cr-doped TI bilayer structures prepared by the modulation-doped growth method. By controlling the magnetic interaction profile, we observe the Dirac hole-mediated ferromagnetism and develop an effective way to manipulate its strength. Besides, the giant spin-orbit torque in such magnetic TI-based heterostructures enables us to demonstrate the current

  1. Pseudoclassical Model of Spinning Particle with Anomalous Magnetic Momentum

    CERN Document Server

    Gitman, D M

    1993-01-01

    A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic momentum is given. The action is written in reparametrization and supergauge invariant form. The Dirac quantization, based on the Hamiltonian analyses of the model, leads to the Dirac-Pauli equation for a particle with an anomalous magnetic momentum in an external electromagnetic field. Due to the structure of first-class constraints in that case, the Dirac quantization demands for consistency to take into account an operators ordering problem.

  2. Observation of anomalous dielectric properties in low-dimensional spin 1/2 α-Cu2V2O7 magnetic system

    Science.gov (United States)

    Chen, Yu-Jen; Chandrasekhar, Kakarla-Devi; Fan, Ko-Jung; Lin, Jiunn-Yuan; Lee, Jenn-Min; Chen, Jin-Ming; Yang, Hung-Duen

    Recently, low-dimensional magnetic systems have received much attention from both theoretical and experimental physics point of view due to their fascinating physical properties. In general, Cu2V2O7 can stabilize at least two sibling polymorphs named as α and β phases. In α phase, Cu2V2O7 crystallized in orthorhombic with Fdd2 space groups. The complex magnetic exchange interaction between the Cu-O-Cu ion within the intra and interchain creates the Dzyaloshinskii-Moriya interaction that leads to weak ferromagnetism below the magnetic transition temperature TN = 34 K. In this study, we present the results of multiple dielectric anomalies observed in the low dimensional spin 1/2 α-Cu2V2O7 magnetic system. The observed dielectric signatures can be ascribed to the complex magnetic interaction α-Cu2V2O7 system. Further, the chemical doping effect on the magnetic and multiferroic properties of α-Cu2V2O7 is underway.

  3. Anomalous Magnetic Moments and Quark Orbital Angular Momentum

    OpenAIRE

    Burkardt, M.; Schnell, G.(University of the Basque Country UPV/EHU, 48080 Bilbao, Spain)

    2005-01-01

    We derive an inequality for the distribution of quarks with non-zero orbital angular momentum, and thus demonstrate, in a model-independent way, that a non-vanishing anomalous magnetic moment requires both a non-zero size of the target as well as the presence of wave function components with quark orbital angular momentum L_z>0.

  4. Magnetic Instability in Accretion Disks with Anomalous Viscosity

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ai-Ping; LI Xiao-Qing

    2004-01-01

    @@ Using the new model of anomalous viscosity, we investigate the magnetic instability in the accretion disks and give the dispersion formula. On the basis of the dispersion relation obtained, it is numerically shown that the instability condition of viscous accretion disk is well consistent with that of the ideal accretion disk, namely there would be magneto-rotational instability in the presence of a vertical weak magnetic field. For a given distance R from the centre of the disk, the growth rate in the anomalous case deviates from the ideal case more greatly when the vertical magnetic field is smaller. The large viscosity limits to the instability. In the two cases, the distributions of growth rate with wave number k approach each other when the magnetic field increases. It greatly represses the effect of viscosity.

  5. Quantum Anomalous Hall Effect in Magnetic Insulator Heterostructure

    OpenAIRE

    Xu, Gang; Jing WANG; FELSER, CLAUDIA; Qi, Xiao-Liang; Zhang, Shou-Cheng

    2014-01-01

    Based on ab initio calculations, we predict that a monolayer of Cr-doped (Bi,Sb)2Te3 and GdI2 heterostructure is a quantum anomalous Hall insulator with a non-trivial band gap up to 38 meV. The principle behind our prediction is that the band inversion between two topologically trivial ferromagnetic insulators can result in a non-zero Chern number, which offers a better way to realize the quantum anomalous Hall state without random magnetic doping. In addition, a simple effective model is pre...

  6. Anomalous magnetic moment and Compton wavelength

    OpenAIRE

    Heyrovska, Raji

    2004-01-01

    The relativistic and quantum theoretical explanations of the magnetic moment anomaly of the electron (or proton) show that it is a complicated function of the fine structure constant. In this work, a simple non-relativistic approach shows that the translational motion of the particle during its spin is responsible for the observed effects.

  7. Anomalous Hall Effect in Geometrically Frustrated Magnets

    Directory of Open Access Journals (Sweden)

    D. Boldrin

    2012-01-01

    space mechanism based on spin chirality that was originally applied to the pyrochlore Nd2Mo2O7 appears unsatisfactory. Recently, an orbital description based on the Aharonov-Bohm effect has been proposed and applied to both the ferromagnetic pyrochlores Nd2Mo2O7 and Pr2Ir2O7; the first of which features long-ranged magnetic order while the latter is a chiral spin liquid. Two further examples of geometrically frustrated conducting magnets are presented in this paper—the kagome-like Fe3Sn2 and the triangular PdCrO2. These possess very different electronic structures to the 3-dimensional heavy-metal pyrochlores and provide new opportunities to explore the different origins of the AHE. This paper summarises the experimental findings in these materials in an attempt to unite the conflicting theoretical arguments.

  8. Quantization of Spinning Particle with Anomalous Magnetic Momentum

    CERN Document Server

    Gitman, D M

    1993-01-01

    A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic moment is given. The leading considerations, to write the action, are gotten from the path integral representation for the causal Green's function of the generalized (by Pauli) Dirac equation for the particle with anomalous magnetic momentum in an external electromagnetic field. The action can be written in reparametrization and supergauge invariant form. Both operator (Dirac) and path-integral (BFV) quantization are discussed. The first one leads to the Dirac-Pauli equation, whereas the second one gives the corresponding propagator. One of the nontrivial points in this case is that both quantizations schemes demand for consistency to take into account an operators ordering problem.

  9. Searches for Magnetic Monopoles and Anomalously Charged Objects with ATLAS

    CERN Document Server

    Katre, Akshay; The ATLAS collaboration

    2016-01-01

    Results of searches for highly ionising particles and particles with anomalously high electric charge produced in proton-proton collisions in the ATLAS detector are presented. Such signatures, encompassing particles with charges from 10 to 60 times the electron charge, involve high levels of ionization in the ATLAS detector and can arise from magnetic monopoles or models involving technicolor, doubly charged Higgs bosons or composite dark matter models.

  10. Anomalous current pinch of a toroidal axisymmetric plasma with stochastic magnetic field perturbations

    Science.gov (United States)

    Wang, Shaojie

    2016-07-01

    Anomalous current pinch, in addition to the anomalous diffusion due to stochastic magnetic perturbations, is theoretically found, which may qualitatively explain the recent DIII-D experiment on resonant magnetic field perturbation. The anomalous current pinch, which may resolve the long-standing issue of seed current in a fully bootstrapped tokamak, is also discussed for the electrostatic turbulence.

  11. Quantum anomalous Hall effect in magnetic topological insulators

    OpenAIRE

    Jing WANG; Lian, Biao; Zhang, Shou-Cheng

    2014-01-01

    The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Here, we give a theoretical introduction to the quantum anomalous Hall (QAH) effect based on magnetic topological insulators in two-dimension (2D) and three-dimension (3D). In 2D topological insulators, magnetic order breaks the symmetry between the counter-propagating helical edge states, and as a result, the quantum spin Hall effect can evolve into the QAH effect. In 3D, magn...

  12. Quantized Anomalous Hall Effect in Magnetic Topological Insulators

    Institute of Scientific and Technical Information of China (English)

    YU Rui

    2011-01-01

    The Hall effect, the anomalous Hall effect (AHE) and the spin Hall effect are thndamental transport processes in solids arising from the Lorentz force and the spin-orbit coupling respectively. The AHE, in which a voltage transverse to the electric current appears even in the absence of an external magnetic field, was first detected in ferromagnetic (FM) metals in 1881 and later found to arise from the spin-orbit coupling (SOC) between the current and magnetic moments.

  13. Quantized Anomalous Hall Effect in Magnetic Topological Insulators

    Institute of Scientific and Technical Information of China (English)

    YU Rui

    2011-01-01

    @@ The Hall effect, the anomalous Hall effect (AHE) and the spin Hall effect are fundamental transport processes in solids arising from the Lorentz force and the spin-orbit coupling respectively.The AHE, in which a voltage transverse to the electric current appears even in the absence of an external magnetic field, was first detected in ferromagnetic (FM) metals in 1881 and later found to arise from the spin-orbit coupling (SOC) between the current and magnetic moments.Recent progress on the mechanism of AHE has established a link between the AHE and the topological nature of the Hall current by adopting the Berry-phase concepts in close analogy to the intrinsic spin Hall effect.Given the experimental discovery of the quantum Hall and the quantum spin Hall effects, it is natural to ask whether the AHE can also be quantized.In a quantized anomalous Hall (QAH) insulator, spontaneous magnetic moments and spin-orbit coupling combine to give rise to a topologically non-trivial electronic structure, leading to the quantized Hall effect without any external magnetic field.

  14. Fermion-Antifermion Condensate Contribution to the Anomalous Magnetic Moment of a Fundamental Dirac Fermion

    CERN Document Server

    Elias, V; Elias, Victor; Sprague, Kevin

    1998-01-01

    We consider the contribution of fermion-antifermion condensates to the anomalous magnetic moment of a fermion in a vacuum in which such condensates exist. The real part of the condensate contribution to the anomalous magnetic moment is shown to be zero. A nonzero imaginary part is obtained below the kinematic threshold for intermediate fermion-antifermion pairs. The calculation is shown to be gauge-parameter independent provided a single fermion mass characterizes both the fermion propagator and condensate-sensitive contributions, suggestive of a dynamically-generated fermion mass. The nonzero imaginary part is then argued to correspond to the kinematic production of the intermediate-state Goldstone bosons anticipated from a chiral-noninvariant vacuum. Finally, speculations are presented concerning the applicability of these results to quark electromagnetic properties.

  15. Tau anomalous magnetic moment in γγ colliders

    Science.gov (United States)

    Peressutti, Javier; Sampayo, Oscar A.

    2012-08-01

    We investigate the possibility of setting model independent limits for a nonstandard anomalous magnetic moment aτNP of the tau lepton, in future γγ colliders based on Compton backscattering. For a hypothetical collider we find that, at various levels of confidence, the limits for aτNP could be improved, compared to previous studies based on LEP1, LEP2 and SLD data. We show the results for a realistic range of the center of mass energy of the e+e- collider. As a more direct application, we also present the results of the simulation for the photon collider at the TESLA project.

  16. Quantum anomalous Hall effect in magnetic topological insulators

    Science.gov (United States)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-12-01

    The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Here, we give a theoretical introduction to the quantum anomalous Hall (QAH) effect based on magnetic topological insulators in two-dimensions (2D) and three-dimensions (3D). In 2D topological insulators, magnetic order breaks the symmetry between the counter-propagating helical edge states, and as a result, the quantum spin Hall effect can evolve into the QAH effect. In 3D, magnetic order opens up a gap for the topological surface states, and chiral edge state has been predicted to exist on the magnetic domain walls. We present the phase diagram in thin films of a magnetic topological insulator and review the basic mechanism of ferromagnetic order in magnetically doped topological insulators. We also review the recent experimental observation of the QAH effect. We discuss more recent theoretical work on the coexistence of the helical and chiral edge states, multi-channel chiral edge states, the theory of the plateau transition, and the thickness dependence in the QAH effect.

  17. Muon Anomalous Magnetic Moment in a Supersymmetric U(1)' Model

    CERN Document Server

    Barger, V; Langacker, P; Lee, H S; Barger, Vernon; Kao, Chung; Langacker, Paul; Lee, Hye-Sung

    2005-01-01

    We study the muon anomalous magnetic moment a_\\mu = (g_\\mu - 2)/2 in a supersymmetric U(1)' model. The neutralino sector has extra components from the superpartners of the U(1)' gauge boson and the extra Higgs singlets that break the U(1)' symmetry. The theoretical maximum bound on the lightest neutralino mass is much smaller than that of the Minimal Supersymmetric Standard Model (MSSM) because of the mixing pattern of the extra components. In a U(1)' model where the U(1)' symmetry is broken by a secluded sector (the S-model), tan\\beta is required to be < 3 to have realistic electroweak symmetry breaking. These facts suggest that the a_\\mu prediction may be meaningfully different from that of the MSSM. We evaluate and compare the muon anomalous magnetic moment in this model and the MSSM and discuss the constraints on tan\\beta and relevant soft breaking terms. There are regions of the parameter space that can explain the experimental deviation of a_\\mu from the Standard Model calculation and yield an accept...

  18. Progress in analytical calculations for the anomalous magnetic moment of the muon

    Energy Technology Data Exchange (ETDEWEB)

    Baikov, P.A. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Maier, A. [Technische Univ. Muenchen (Germany). Physik Dept. T31; Marquard, P. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2013-11-15

    We present results for certain classes of diagrams contributing to the anomalous magnetic moment of the muon at five-loop order. Our method is based on first constructing an approximating function for the vacuum polarization function of the photon at four loop order which later can be numerically integrated to obtain the anomalous magnetic moment of the muon.

  19. Anomalous wave structure in magnetized materials described by non-convex equations of state

    Energy Technology Data Exchange (ETDEWEB)

    Serna, Susana, E-mail: serna@mat.uab.es [Departament de Matematiques, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Marquina, Antonio, E-mail: marquina@uv.es [Departamento de Matematicas, Universidad de Valencia, 46100 Burjassot, Valencia (Spain)

    2014-01-15

    We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynamic properties of the material and the magnetic field as well as its possible rotation. We demonstrate that phase transitions induced by material properties do not necessarily imply the loss of genuine nonlinearity of the wavefields as is the case in classical hydrodynamics. The analytical expression of the nonlinearity factor allows us to determine the specific amount of magnetic field necessary to prevent formation of complex structure induced by phase transition in the material. We illustrate our analytical approach by considering two non-convex EOS that exhibit phase transitions and anomalous behavior in the evolution. We present numerical experiments validating the analysis performed through a set of one-dimensional Riemann problems. In the examples we show how to determine the appropriate amount of magnetic field in the initial conditions of the Riemann problem to transform a thermodynamic composite wave into a simple nonlinear wave.

  20. Anomalous wave structure in magnetized materials described by non-convex equations of state

    International Nuclear Information System (INIS)

    We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynamic properties of the material and the magnetic field as well as its possible rotation. We demonstrate that phase transitions induced by material properties do not necessarily imply the loss of genuine nonlinearity of the wavefields as is the case in classical hydrodynamics. The analytical expression of the nonlinearity factor allows us to determine the specific amount of magnetic field necessary to prevent formation of complex structure induced by phase transition in the material. We illustrate our analytical approach by considering two non-convex EOS that exhibit phase transitions and anomalous behavior in the evolution. We present numerical experiments validating the analysis performed through a set of one-dimensional Riemann problems. In the examples we show how to determine the appropriate amount of magnetic field in the initial conditions of the Riemann problem to transform a thermodynamic composite wave into a simple nonlinear wave

  1. Lepton anomalous magnetic moments from twisted mass fermions

    CERN Document Server

    Burger, Florian; Jansen, Karl; Petschlies, Marcus

    2014-01-01

    We present our results for the leading-order hadronic quark-connected contributions to the electron, the muon, and the tau anomalous magnetic moments obtained with four dynamical quarks. Performing the continuum limit and an analysis of systematic effects, full agreement with phenomenological results is found. To estimate the impact of omitting the quark-disconnected contributions to the hadronic vacuum polarisation we investigate them on one of the four-flavour ensembles. Additionally, the light quark contributions on the four-flavour sea are compared to the values obtained for $N_f=2$ physically light quarks. In the latter case different methods to fit the hadronic vacuum polarisation function are tested.

  2. Improved Measurement of the Positive Muon Anomalous Magnetic Moment

    CERN Document Server

    Brown, H N; Carey, R M; Cushman, P B; Danby, G T; Debevec, P T; Deng, H; Deninger, W J; Dhawan, S K; Druzhinin, V P; Duong, L; Earle, W; Efstathiadis, E F; Fedotovich, G V; Farley, Francis J M; Giron, S; Gray, F; Grosse-Perdekamp, M; Grossmann, A; Haeberlen, U; Hare, M; Hazen, E S; Hertzog, D W; Hughes, V W; Iwasaki, M; Jungmann, Klaus; Kawall, D; Kawamura, M; Khazin, B I; Kindem, J; Krienen, F; Kronkvist, I J; Larsen, R; Lee, Y Y; Logashenko, I B; McNabb, R; Meng, W; Mi, J; Miller, J P; Morse, W M; Onderwater, Gerco; Orlov, Yu F; Ozben, C; Polly, C; Pai, C; Paley, J M; Pretz, J; Prigl, R; zu Putlitz, Gisbert; Redin, S I; Rind, O; Roberts, B L; Ryskulov, N M; Sedykh, S N; Semertzidis, Y K; Shatunov, Yu M; Solodov, E P; Sossong, M; Steinmetz, A; Sulak, Lawrence R; Timmermans, C; Trofimov, A V; Urner, D; Von Walter, P; Warburton, D; Winn, D; Yamamoto, A; Zimmerman, D

    2000-01-01

    A new measurement of the positive muon's anomalous magnetic moment has been made at the Brookhaven Alternating Gradient Synchrotron using the direct injection of polarized muons into the superferric storage ring. The angular frequency difference omega_{a} between the angular spin precession frequency omega_{s} and the angular orbital frequency omega_{c} is measured as well as the free proton NMR frequency omega_{p}. These determine R = omega_{a} / omega_{p} = 3.707~201(19) times 10^{-3}. With mu_{mu} / mu_{p} = 3.183~345~39(10) this gives a_{mu^+} = 11~659~191(59) times 10^{-10} (pm 5 ppm), in good agreement with the previous CERN and BNL measurements for mu^+ and mu^-, and with the standard model prediction.

  3. Precision Measurement of the Anomalous Magnetic Moment of the Muon

    CERN Document Server

    Ozben, C S

    2002-01-01

    The muon g-2 experiment at Brookhaven National Laboratory measures the anomalous magnetic moment of the muon, $a_\\mu$, very precisely. This measurement tests the Standard Model theory. The analysis for the data collected in 2000 (a $\\mu^+$ run) is completed and the accuracy on $a_\\mu$ is improved to 0.7 ppm, including statistical and systematic errors. The data analysis was performed blindly between the precession frequency and the field analysis groups in order to prevent a possible bias in the $a_\\mu$ result. The observed difference between the theory and our most recent experimental result is quite important for further studies of the Standard Model theory. In 2001, we ran for the first time with $\\mu^-$ and the analysis of this data will provide $a_\\mu$ with similar statistical power.

  4. Rosenbluth scattering and Pauli's approach to anomalous magnetic moments

    International Nuclear Information System (INIS)

    In standard QED particle interactions are evaluated using minimal coupling, coupling the particles solely through their (electric monopole) charges. The Direc Hamiltonian is used to describe the interaction of a single spin-1/2 particle with an electromagnetic field. Pauli suggested the addition of a further gauge-invariant term to the Dirac Hamiltonian where the coupling constant for this extra term should not be directly linked to the particle's electric charge. We study some of the effects of this additional term and show that for the scattering of electrons off protons, the first-order Pauli-Dirac analysis has at least as good agreement with experiment as previous analyses based on the Dirac Hamiltonian. We show that Rosenbluth used the incorrect sign on the anomalous magnetic moment of the proton. (author)

  5. Precise quantization of anomalous Hall effect near zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Bestwick, A. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fox, E. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kou, Xufeng [Univ. of California, Los Angeles, CA (United States); Pan, Lei [Univ. of California, Los Angeles, CA (United States); Wang, Kang L. [Univ. of California, Los Angeles, CA (United States); Goldhaber-Gordon, D. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-05-04

    In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.

  6. Anomalous Nernst Effect of Perpendicularly Magnetic Anisotropy TbFeCo Thin Films

    Science.gov (United States)

    Ando, Ryo; Komine, Takashi; Hasegawa, Yasuhiro

    2016-07-01

    In this study, we investigated anomalous Nernst effect (ANE) of perpendicularly magnetized TbFeCo thin films with various Tb content, and especially studied the relation between ANE and anomalous Hall effect. As a result, the hysteresis of anomalous Nernst coefficient showed the same behavior as that of anomalous Hall resistivity, and the sign of anomalous Nernst coefficient was consistent with that of anomalous Hall voltage in any Tb content, whereas the Seebeck coefficient and the resistivity were almost constant even if the applied magnetic field was varied. Taking into account of thermoelectric coefficient tensor, it was revealed that the off-diagonal thermopower corresponding to the ANE in TbFeCo thin films is the product of Hall angle and Seebeck coefficient.

  7. New Physics Contributions to the Muon Anomalous Magnetic Moment

    CERN Document Server

    Queiroz, Farinaldo S

    2014-01-01

    We consider the contributions of individual new particles to the anomalous magnetic moment of the muon, utilizing the generic framework of simplified models. We also present analytic results for all possible one-loop contributions, allowing easy application of these results for more complete models which predict more than one particle capable of correcting the muon magnetic moment. Additionally, we provide a Mathematica code to allow the reader straightforwardly compute any 1-loop contribution. Furthermore, we derive bounds on each new particle considered, assuming either the absence of other significant contributions to $a_\\mu$ or that the anomaly has been resolved by some other mechanism. In summary we found the following particles capable of explaining the current discrepancy, assuming unit couplings: $2$TeV ($0.3$TeV) neutral scalar with pure scalar (chiral) couplings, $4$TeV doubly charged scalar with pure pseudoscalar coupling, $0.3-1$TeV neutral vector boson depending on what couplings are used (vector...

  8. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    CERN Document Server

    Mukhopadhyay, Banibrata

    2016-01-01

    We explore the possibility that soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are powered by highly magnetized white dwarfs (B-WDs). We take a sample of SGRs and AXPs and provide the possible parameter space in mass, radius, and surface magnetic field based on their observed properties (period and its derivative) and the assumption that these sources obey the mass-radius relation derived for the B-WDs. The radius and magnetic field of B-WDs are adequate to explain energies in SGRs/AXPs as the rotationally powered energy. In addition, B-WDs also adequately explain the perplexing radio transient GCRT J1745-3009 as a white dwarf pulsar. Note that the radius and magnetic fields of B-WDs are neither extreme (unlike of highly magnetized neutron stars) nor ordinary (unlike of magnetized white dwarfs, yet following the Chandrasekhar's mass-radius relation (C-WDs)). In order to explain SGRs/AXPs, while the highly magnetized neutron stars require an extra, observationally not well established yet, ...

  9. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    Science.gov (United States)

    Mukhopadhyay, Banibrata; Rao, A. R.

    2016-05-01

    We explore the possibility that soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are powered by highly magnetized white dwarfs (B-WDs). We take a sample of SGRs and AXPs and provide the possible parameter space in mass, radius, and surface magnetic field based on their observed properties (period and its derivative) and the assumption that these sources obey the mass-radius relation derived for the B-WDs. The radius and magnetic field of B-WDs are adequate to explain energies in SGRs/AXPs as the rotationally powered energy. In addition, B-WDs also adequately explain the perplexing radio transient GCRT J1745-3009 as a white dwarf pulsar. Note that the radius and magnetic fields of B-WDs are neither extreme (unlike of highly magnetized neutron stars) nor ordinary (unlike of magnetized white dwarfs, yet following the Chandrasekhar's mass-radius relation (C-WDs)). In order to explain SGRs/AXPs, while the highly magnetized neutron stars require an extra, observationally not well established yet, source of energy, the C-WDs predict large ultra-violet luminosity which is observationally constrained from a strict upper limit. Finally, we provide a set of basic differences between the magnetar and B-WD hypotheses for SGRs/AXPs.

  10. Anomalous properties of spin-extended chiral fermions

    CERN Document Server

    Elbistan, M

    2015-01-01

    The spin-extended semiclassical chiral fermion (we call the S-model), which had been used to derive the twisted Lorentz symmetry of the "spin-enslaved" chiral chiral fermion (we call the c-model) is equivalent to the latter in the free case, however coupling to an external electromagnetic field yields inequivalent systems. The difference is highlighted by the inconsistency of spin enslavement within the spin-extended framework. The S-model exhibits nevertheless similar though slightly different anomalous properties as the usual c-model does.

  11. Particle with spin 2 and anomalous magnetic moment in external electromagnetic and gravitational fields

    CERN Document Server

    Kisel, V V; Red'kov, V M

    2011-01-01

    Tensor 50-component form of the first order relativistic wave equation for a particle with spin 2 and anomalous magnetic moment is extended to the case of an arbitrary curved space-time geometry. An additional parameter considered in the presence of only electromagnetic field as related to anomalous magnetic moment, turns to determine additional interaction terms with external geometrical background through Ricci R_{kl} and Riemann R_{klmn} tensors.

  12. Influence of External Magnetic Field on Anomalous Skin Effects in Inductively Coupled Plasmas

    Institute of Scientific and Technical Information of China (English)

    MAO Ming; WANG You-Nian

    2004-01-01

    @@ Using a one-dimensional slab model, we study the influence of the external static magnetic field on the anomalous skin effects in the inductively coupled plasma. The rf electromagnetic field in the plasma is determined by solving the linearized Boltzmann equation incorporating with the Maxwell equations. The numerical results show that,due to the existence of the external magnetic field, the anomalous skin effects are greatly enhanced and the number of regions with negative absorption is decreased.

  13. Anomalous Temperature Dependence of Magnetic Moment in Monodisperse Antiferromagnetic Nanoparticles

    Science.gov (United States)

    Gillaspie, Dane; Gu, B.; Wang, W.; Shen, J.

    2005-03-01

    1 Condensed Matter Sciences Division, Oak Ridge National Laboratory*, TN 37831 2 Department of Physics and Astronomy, The University of Tennessee, TN 37996 3 Environmental Sciences Division, Oak Ridge National Laboratory*, TN 37831 Recent experiments [1] and theory [2] from AFM nanoparticles showed that they exhibit sizable net magnetization, which increases with increasing temperature. In order to further understand such peculiar temperature dependence, we have measured the magnetic properties of monodisperse hematite (α-Fe2O3) nanoparticles, grown using a microemulsion precipitation technique, which minimizes the impact of the particle moment distribution on the measured properties of the samples. Our measured results indicate that the net magnetization of these nanoparticles, when small, indeed increases linearly with increasing temperature. This is in sharp contrast to the bulk-like behavior of α-Fe2O3, which was observed in particles with size larger than 120 nm. [1] M. Seehra et al, Phys. Rev. B 61, 3513 (2000) [2] S. Mørup, C. Frandsen, Phys. Rev. Lett. 92, 217201 (2004) *Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725

  14. Thickness Dependence of the Quantum Anomalous Hall Effect in Magnetic Topological Insulator Films.

    Science.gov (United States)

    Feng, Xiao; Feng, Yang; Wang, Jing; Ou, Yunbo; Hao, Zhenqi; Liu, Chang; Zhang, Zuocheng; Zhang, Liguo; Lin, Chaojing; Liao, Jian; Li, Yongqing; Wang, Li-Li; Ji, Shuai-Hua; Chen, Xi; Ma, Xucun; Zhang, Shou-Cheng; Wang, Yayu; He, Ke; Xue, Qi-Kun

    2016-08-01

    The evolution of the quantum anomalous Hall effect with the thickness of Cr-doped (Bi,Sb)2 Te3 magnetic topological insulator films is studied, revealing how the effect is caused by the interplay of the surface states, band-bending, and ferromagnetic exchange energy. Homogeneity in ferromagnetism is found to be the key to high-temperature quantum anomalous Hall material. PMID:27166762

  15. Carrier-independent ferromagnetism and giant anomalous Hall effect in magnetic topological insulator

    OpenAIRE

    Chang, Cui-Zu; Zhang, Jin-song; Liu, Min-Hao; Zhang, Zuo-Cheng; Feng, Xiao; Li, Kang; Wang, Li-Li; Chen, Xi; Dai, Xi; Fang, Zhong; Qi, Xiao-Liang; Zhang, Shou-Cheng; Wang, Yayu; He, Ke; Ma, Xu-Cun

    2011-01-01

    Breaking the time-reversal symmetry of a topological insulator (TI) by ferromagnetism can induce exotic magnetoelectric phenomena such as quantized anomalous Hall (QAH) effect. Experimental observation of QAH effect in a magnetically doped TI requires ferromagnetism not relying on the charge carriers. We have realized the ferromagnetism independent of both polarity and density of carriers in Cr-doped BixSb2-xTe3 thin films grown by molecular beam epitaxy. Meanwhile, the anomalous Hall effect ...

  16. `Anomalous' magnetic fabrics of dikes in the stable single domain/superparamagnetic threshold

    Science.gov (United States)

    Soriano, Carles; Beamud, Elisabet; Garcés, Miguel; Ort, Michael H.

    2016-02-01

    `Anomalous' magnetic fabrics in dikes that appear to indicate flow into the wall confound many workers. Here, we present extensive magnetic data on five dikes from Tenerife, Canary Islands, and use these to interpret the causes of the anomalous fabrics. Comparison of the anisotropy of magnetic susceptibility (AMS) and anhysteretic magnetization (AARM) results show that, in some cases, the anomalous fabrics are caused by single-domain grains, which produce AMS fabrics perpendicular to the grain elongation, whereas AARM fabrics are parallel. To check this, hysteresis experiments were used to characterize the domain state. These show most are mixtures of pseudo-single-domain or single-domain plus multi-domain particles, but many have wasp-waisted hysteresis loops, likely indicating mixed populations of stable single-domain and superparamagnetic grains. First-order reversal curves were used to better characterize this and show mixtures of stable single-domain and superparamagnetic grains dominate the magnetic signal. Magnetic particles at the stable single-domain/superparamagnetic threshold are unstable at timespans relevant to the analytical techniques, so they produce complicated results. This suggests that anomalous AMS fabrics in dikes cannot simply be attributed to elongated stable single-domain particles and that mixtures of the different grain types can produce hybrid fabrics, in which the fabrics are neither perpendicular or parallel to the dike plane, that are difficult to interpret without extensive magnetic analysis.

  17. Solution of Dirac Equation for Charged and Neutral Fermions with Anomalous Magnetic Moments in Uniform Magnetic Field

    OpenAIRE

    Pitschmann, M.; A. N. Ivanov

    2012-01-01

    The Dirac equation for charged and neutral fermions with anomalous magnetic moments is solved in a uniform magnetic field. We find the relativistic wave functions and energy spectra. In the non-relativistic limit the wave functions and energy spectra of charged fermions agree with the known solutions of the Schroedinger equation.

  18. Vacuum effects in magnetic field with with account for fermion anomalous magnetic moment and axial-vector interaction

    Science.gov (United States)

    Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir

    2016-05-01

    We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.

  19. Prediction of the anomalous magnetic moment of nucleon from the nucleon anomaly

    CERN Document Server

    Lin, Y C

    1995-01-01

    We construct the effective anomaly lagrangian involving nucleons and photons by using current-current coupling method. The contribution of this lagrangian to the anomalous magnetic moment of nucleon is purely isovector. The anomalous magnetic moment of proton, \\kappa_P, can be calculated from the this lagrangian and it is found to be \\kappa_P^{Theor.} = 1.77, which is in excellent agreement with the experimental value \\kappa_P^{Exp.} = 1.79. While the case of neutron, \\kappa_N^{Theor.} = -2.58 as compared to \\kappa_N^{Exp.} =-1.91, is less satisfactory, but the sign is correct.

  20. Is the anomalous magnetic moment the consequence of a non-classical transformation for rotating frames?

    Energy Technology Data Exchange (ETDEWEB)

    Gisin, B V [Department of Electrical Engineering - Physical Electronics, Faculty of Engineering, Tel-Aviv University Tel-Aviv 69978 (Israel)

    2002-08-01

    We consider the anomalous magnetic moment from an 'optical viewpoint' using an analogy between the motion of a particle with a magnetic moment in a magnetic field and the propagation of an optical pulse through an electro-optical crystal in an electric field. We show that an optical experiment similar to electron magnetic resonance is possible in some electro-optical crystals possessing the Faraday effect. This phenomenon is described by an analogue of the Pauli equation extracted from the Maxwell equation in the slowly varied amplitude approximation. In such an experiment the modulation by rotating fields plays a significant role. From the optical viewpoint the modulation assumes introducing the concept of a point rotation frame with the rotation axis at every point originated from the concept of the optical indicatrix (index ellipsoid). We discuss the connection between the non-classical transformation by transition from one such frame to another and an anomalous magnetic moment.

  1. Spontaneous magnetization and anomalous Hall effect in an emergent Dice lattice

    Science.gov (United States)

    Dutta, Omjyoti; Przysiężna, Anna; Zakrzewski, Jakub

    2015-06-01

    Ultracold atoms in optical lattices serve as a tool to model different physical phenomena appearing originally in condensed matter. To study magnetic phenomena one needs to engineer synthetic fields as atoms are neutral. Appropriately shaped optical potentials force atoms to mimic charged particles moving in a given field. We present the realization of artificial gauge fields for the observation of anomalous Hall effect. Two species of attractively interacting ultracold fermions are considered to be trapped in a shaken two dimensional triangular lattice. A combination of interaction induced tunneling and shaking can result in an emergent Dice lattice. In such a lattice the staggered synthetic magnetic flux appears and it can be controlled with external parameters. The obtained synthetic fields are non-Abelian. Depending on the tuning of the staggered flux we can obtain either anomalous Hall effect or its quantized version. Our results are reminiscent of Anomalous Hall conductivity in spin-orbit coupled ferromagnets.

  2. Anomalous evolution of interfaces in Fe/Ag magnetic multilayer

    Science.gov (United States)

    Sharma, Gagan; Gupta, Ranjeeta; Kumar, Dileep; Gupta, Ajay

    2013-12-01

    Interfaces greatly influence the magnetic properties of multilayer nanostructures. In the present work, the x-ray standing wave (XSW) technique along with conversion electron Mössbauer spectroscopy have been used to study the evolution of interfaces in Fe/Ag system as a function of thermal annealing. The XSW technique has sufficient depth resolution so as to determine the concentration profiles of Fe across the two interfaces, namely Fe-on-Ag and Ag-on-Fe independently. In as-deposited Ag/Fe/Ag trilayer, Fe-on-Ag interface has a substantially higher roughness of 1.3 nm as compared to 0.9 nm of Ag-on-Fe interface. It is shown that the observed difference in the roughness of the two interfaces is due to a substantial intermixing between Fe and Ag occurring preferentially at Fe-on-Ag interface. With thermal annealing, the two interfaces exhibit opposite behaviour; while Fe-on-Ag interface exhibits an initial sharpening, Ag-on-Fe interface exhibits a monotonous broadening. Two competing processes occur at the interfaces, (i) interface sharpening as a result of de-mixing, driven by a large positive heat of mixing between Fe and Ag and (ii) increase in topological roughness due to increased thermal agitation. This results in a non-monotonous variation in the roughness of Fe-on-Ag interface. At sufficiently high temperature the layered structure is completely destroyed, leading to formation of Fe and Ag nanoparticles.

  3. Anomalous sound propagation due to the horizontal variation of seabed acoustic properties

    Institute of Scientific and Technical Information of China (English)

    LI Zhenglin; ZHANG Renhe; PENG Zhaohui; LI Xilu

    2004-01-01

    The sound propagation in shallow water is greatly influenced by the acoustic properties of seabed. An anomalous transmission loss was observed in an experiment, and a range dependent bottom model with horizontal variation of seabed acoustic property is proposed and could be well used to explain the anomalous phenomena. It is shown that the horizontal variation of bottom properties has a great effect on underwater sound propagation, and it should be given much attention in sound propagation and geoacoustic inversion problems.

  4. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    GROSU Marian C

    2015-05-01

    Full Text Available A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a solution hard magnetic polymer based. As hard magnetic powder, barium hexaferrite (BaFe12O19 was selected. The plain woven fabric used as base has been coated with five solutions having different amounts of hard magnetic powder (15% - 45% in order to obtain five different magnetic woven fabrics. A comparison of physical properties regarding weight (g/m2, thickness (mm, degree of charging (% and magnetic properties of magnetic woven samples were presented. Saturation magnetizing (emu/g, residual magnetizing (emu/g and coercive force (kA/m of pure hard magnetic powder and woven fabrics have been studied as hysteresis characteristics. The magnetic properties of the woven fabrics depend on the mass percentage of magnetic powder from coating solution. Also, the residual magnetism and coercive field of woven fabrics represents only a part of bulk barium hexafferite residual magnetism and coercive field.

  5. Leading-order hadronic contributions to the electron and tau anomalous magnetic moments

    CERN Document Server

    Burger, Florian; Jansen, Karl; Petschlies, Marcus

    2015-01-01

    The leading hadronic contributions to the anomalous magnetic moments of the electron and the $\\tau$-lepton are determined by a four-flavour lattice QCD computation with twisted mass fermions. The continuum limit is taken and systematic uncertainties are quantified. Full agreement with results obtained by phenomenological analyses is found.

  6. Leading-order hadronic contributions to the electron and tau anomalous magnetic moments

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Florian; Hotzel, Grit [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus)

    2015-01-15

    The leading hadronic contributions to the anomalous magnetic moments of the electron and the τ-lepton are determined by a four-flavour lattice QCD computation with twisted mass fermions. The continuum limit is taken and systematic uncertainties are quantified. Full agreement with results obtained by phenomenological analyses is found.

  7. Final report of the E821 muon anomalous magnetic moment measurement at BNL

    NARCIS (Netherlands)

    Bennett, GW; Bousquet, B; Brown, HN; Bunce, G; Carey, RM; Cushman, P; Danby, GT; Debevec, PT; Deile, M; Deng, H; Deninger, W; Dhawan, SK; Druzhinin, VP; Duong, L; Efstathiadis, E; Farley, FJM; Fedotovich, GV; Giron, S; Gray, FE; Grigoriev, D; Grosse-Perdekamp, M; Grossmann, A; Hare, MF; Hertzog, DW; Huang, [No Value; Hughes, VW; Iwasaki, M; Jungmann, Klaus-Peter; Kawall, D; Kawamura, M; Khazin, BI; Kindem, J; Krienen, F; Kronkvist, [No Value; Lam, A; Larsen, R.; Lee, YY; Logashenko, [No Value; McNabb, R; Meng, W; Mi, J; Miller, JP; Mizumachi, Y; Morse, WM; Nikas, D; Onderwater, Gerco; Orlov, Y; Ozben, CS; Paley, JM; Peng, Q; Polly, CC; Pretz, J; Prigl, R; Putlitz, GZ; Qian, T; Redin, SI; Rind, O; Roberts, BL; Ryskulov, N; Sedykh, S; Semertzidis, YK; Shagin, P; Shatunov, YM; Sichtermann, EP; Solodov, E; Sossong, M; Steinmetz, A; Sulak, LR; Timmermans, C; Trofimov, A; Urner, D; von Walter, P; Warburton, D; Winn, D; Yamamoto, A; Zimmerman, D

    2006-01-01

    We present the final report from a series of precision measurements of the muon anomalous magnetic moment, a(mu)=(g-2)/2. The details of the experimental method, apparatus, data taking, and analysis are summarized. Data obtained at Brookhaven National Laboratory, using nearly equal samples of positi

  8. The effect of interfacial intermixing on magnetization and anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing

    2015-05-01

    The effect of interfacial intermixing on magnetization and anomalous Hall effect (AHE) in Co/Pd multilayers is studied by using rapid thermal annealing to enhance the interfacial diffusion. The dependence of saturation magnetization and coercivity on the temperature of rapid thermal annealing at 5 K is discussed. It is found that AHE is closely related to the relative thickness of the Co and Pd layers. Localized paramagnetism has been observed which destroys AHE, while AHE can be enhanced by annealing.

  9. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    CERN Document Server

    Mukhopadhyay, Banibrata

    2016-01-01

    We show that the soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) can be explained as recently proposed highly magnetized white dwarfs (B-WDs). The radius and magnetic field of B-WDs are perfectly adequate to explain energies in SGRs/AXPs as the rotationally powered energy. While the highly magnetized neutron stars require an extra, observationally not well established yet, source of energy, the magnetized white dwarfs, yet following Chandrasekhar's theory (C-WDs), exhibit large ultra-violet luminosity which is observationally constrained from a strict upper limit.

  10. Anomalous metamagnetic-like transition in a FeRh/Fe$_3$Pt interface occurring at T120 K in the field-cooled-cooling curves for low magnetic fields

    OpenAIRE

    Salem-Sugui Jr., S.; Alvarenga, A. D.; R. D. Noce; Guimarães, R. B.; Salazar Mejia, C.; Salim, H.; Gandra, F. G.

    2012-01-01

    We report on the magnetic properties of a special configuration of a FeRh thin film. An anomalous behavior on the magnetisation vs. temperature was observed when low magnetic fields are applied in the plane of a thin layer of FeRh deposited on ordered Fe$_3$Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetisation curve at temperatures near 120 K in samples without any heat treatment.

  11. Anomalous metamagnetic-like transition in a FeRh/Fe3Pt interface occurring at T ≈ 120 K in the field-cooled-cooling curves for low magnetic fields

    Science.gov (United States)

    Salem-Sugui, S.; Alvarenga, A. D.; Noce, R. D.; Guimarães, R. B.; Mejia, C. Salazar; Salim, H.; Gandra, F. G.

    2012-09-01

    We report on the magnetic properties of a special configuration of a FeRh thin film. An anomalous behavior on the magnetisation vs. temperature was observed when low magnetic fields are applied in the plane of a thin layer of FeRh deposited on ordered Fe3Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetisation curve at temperatures near 120 K in samples without any heat treatment.

  12. Anomalous metamagnetic-like transition in a FeRh/Fe3Pt interface occurring at T ≈ 120 K in the field-cooled-cooling curves for low magnetic fields

    Directory of Open Access Journals (Sweden)

    S. Salem-Sugui Jr.

    2012-09-01

    Full Text Available We report on the magnetic properties of a special configuration of a FeRh thin film. An anomalous behavior on the magnetisation vs. temperature was observed when low magnetic fields are applied in the plane of a thin layer of FeRh deposited on ordered Fe3Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetisation curve at temperatures near 120 K in samples without any heat treatment.

  13. Anomalous Magnetic Excitations of Cooperative Tetrahedral Spin Clusters

    DEFF Research Database (Denmark)

    Prsa, K.; Rønnow, H.M.; Zaharko, O.;

    2009-01-01

    An inelastic neutron scattering study of Cu2Te2O5X2 (X=Cl, Br) shows strong dispersive modes with large energy gaps persisting far above T-N, notably in Cu2Te2O5Br2. The anomalous features: a coexisting unusually weak Goldstone-like mode observed in Cu2Te2O5Cl2 and the size of the energy gaps can...... cannot be explained by existing theories, such as our mean-field or random-phase approximation. We argue that our findings represent a new general type of behavior due to intercluster quantum fluctuations and call for development of a new theoretical approach....

  14. Anomalous origin of the occipital artery diagnosed by magnetic resonance angiography

    Energy Technology Data Exchange (ETDEWEB)

    Uchino, Akira; Saito, Naoko; Mizukoshi, Waka; Okada, Yoshitaka [Saitama Medical University International Medical Center, Department of Diagnostic Radiology, Hidaka, Saitama (Japan)

    2011-11-15

    It is well known that the occipital artery (OA) can arise from the internal carotid artery (ICA) or vertebral artery (VA). However, the incidence of an anomalously originating OA has not been reported. We investigate its incidence and characteristic features on magnetic resonance angiography (MRA). We retrospectively reviewed MRA images of 2,866 patients that included the carotid bifurcation; images were obtained using a standard noncontrast MRA protocol and two 1.5-T MR units. We diagnosed six cases (seven arteries) of anomalously originating OA, which represented an incidence of 0.21%. The OA arose from the ICA in four patients (five arteries), from the carotid bifurcation in one, and from the VA in one. Five of the seven arteries occurred on the right. Anomalously originating OA is rare and occurs with right-side predominance. Correct diagnosis is necessary before or during cerebral angiography, especially when selective catheterization to the OA is required. (orig.)

  15. Anomalous shift of magnetic diffuse scattering studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Prokes, K [Helmholtz Centre Berlin for Materials and Energy, SF-2, Glienicker Strasse 100, 14109 Berlin (Germany); Lander, G H [European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, 76125 Karlsruhe (Germany); Bernhoeft, N [CEA Grenoble, DRFMC/SPSMS, F-38054 Grenoble (France)], E-mail: prokes@helmholtz-berlin.de

    2009-07-15

    Neutron diffraction results, in the vicinity of the magnetic phase transition of USb and MnF{sub 2}, are reported. The thermal evolution of the magnetic diffuse signal and nuclear Bragg reflections demonstrate that the centre of gravity of the magnetic signals does not lie at the predicted position as calculated from nuclear reflections. This phenomenon, called the q-shift, was first found using resonance x-ray scattering (RXS). The present results show that, (i) the effect is not an artefact of RXS and is also found with neutrons (ii) that the effect arises from the bulk of the sample and is not restricted to the near surface layer ({approx}2000 A) associated with the RXS probe in actinide systems, (iii) the effect is not restricted to actinide compounds.

  16. Composite Higgs Models, Technicolor and The Muon Anomalous Magnetic Moment

    CERN Document Server

    Doff, A

    2015-01-01

    We revisit the muon magnetic moment (g-2) in the context of Composite Higgs models and Technicolor, and provide general analytical expressions for computing the muon magnetic moment stemming from new fields such as, neutral gauge bosons, charged gauge bosons, neutral scalar, charged scalars, and exotic charged leptons type of particles. Under general assumptions we assess which particle content could address the $g-2_{\\mu}$ excess. Moreover, we take a conservative approach and derive stringent limits on the particle masses in case the anomaly is otherwise resolved and comment on electroweak and collider bounds. Lastly, for concreteness we apply our results to a particular Technicolor model.

  17. Anomalous transport model study of chiral magnetic effects in heavy ion collisions

    CERN Document Server

    Sun, Yifeng; Li, Feng

    2016-01-01

    Using an anomalous transport model for massless quarks, we study the effect of magnetic field on the elliptic flows of quarks and antiquarks in relativistic heavy ion collisions. With initial conditions from a blast wave model and assuming that the strong magnetic field produced in non-central heavy ion collisions can last for a sufficiently long time, we obtain an appreciable electric quadrupole moment in the transverse plane of a heavy ion collision, which subsequently leads to a splitting between the elliptic flows of quarks and antiquarks as expected from the chiral magnetic wave formed in the produced QGP and observed in experiments at the Relativistic Heavy Ion Collider (RHIC).

  18. The hadronic light-by-light contribution to the muon anomalous magnetic moment and renormalization group for EFT

    Directory of Open Access Journals (Sweden)

    Abyaneh Mehran Zahiri

    2012-12-01

    Full Text Available We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.

  19. The hadronic light-by-light contribution to the muon anomalous magnetic moment and renormalization group for EFT

    CERN Document Server

    Bijnens, Johan

    2012-01-01

    We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.

  20. Artificial ferroelectricity due to anomalous Hall effect in magnetic tunnel junctions

    OpenAIRE

    Vedyayev, A.; Ryzhanova, N.; Strelkov, N.; Dieny, B

    2012-01-01

    We theoretically investigated Anomalous Hall Effect (AHE) and Spin Hall Effect (SHE) transversally to the insulating spacer O, in magnetic tunnel junctions of the form F/O/F where F are ferromagnetic layers and O represents a tunnel barrier. We considered the case of purely ballistic (quantum mechanical) transport, taking into account the assymetric scattering due to spin-orbit interaction in the tunnel barrier. AHE and SHE in the considered case have a surface nature due to proximity effect....

  1. N=2-Maxwell-Chern-Simons Model with Anomalous Magnetic Moment Coupling via Dimensional Reduction

    CERN Document Server

    Christiansen, H R; Helayël-Neto, José A; Mansur, L R; Nogueira, A L M A

    1999-01-01

    An N=1--supersymmetric version of the Cremmer-Scherk-Kalb-Ramond model with non-minimal coupling to matter is built up both in terms of superfields and in a component-field formalism. By adopting a dimensional reduction procedure, the N=2--D=3 counterpart of the model comes out, with two main features: a genuine (diagonal) Chern-Simons term and an anomalous magnetic moment coupling between matter and the gauge potential.

  2. Leading-order hadronic contributions to the lepton anomalous magnetic moments from the lattice

    Science.gov (United States)

    Burger, Florian; Feng, Xu; Jansen, Karl; Petschlies, Marcus; Pientka, Grit; Renner, Dru B.

    2016-04-01

    The hadronic leading-order (hlo) contribution to the lepton anomalous magnetic moments alhlo of the Standard Model leptons still accounts for the dominant source of the uncertainty of the Standard Model estimates. We present the results of an investigation of the hadronic leading order anomalous magnetic moments of the electron, muon and tau lepton from first principles in twisted mass lattice QCD. With lattice data for multiple pion masses in the range 230MeV ≲ mPS ≲ 490 MeV, multiple lattice volumes and three lattice spacings we perform the extrapolation to the continuum and to the physical pion mass and check for all systematic uncertainties in the lattice calculation. As a result we calculate alhlo for the three Standard Model leptons with controlled statistical and systematic error in agreement with phenomenological determinations using dispersion relations and experimental data. In addition, we also give a first estimate of the hadronic leading order anomalous magnetic moments from simulations directly at the physical value of the pion mass.

  3. Leading-order hadronic contributions to the lepton anomalous magnetic moments from the lattice

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Florian [OakLabs GmbH, Hennigsdorf (Germany); Feng, Xu [Columbia University, New York, NY (United States). Dept. of Physics; Jansen, Karl [DESY Zeuthen (Germany). NIC; Petschlies, Marcus [Bonn Univ. (Germany). Inst. fuer Strahlen- und Kernphysik; Pientka, Grit [Humboldt-Univ. Berlin (Germany). Inst. fuer Physik; Renner, Dru B. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2015-11-15

    The hadronic leading-order (hlo) contribution to the lepton anomalous magnetic moments a{sup hlo}{sub l} of the Standard Model leptons still accounts for the dominant source of the uncertainty of the Standard Model estimates. We present the results of an investigation of the hadronic leading order anomalous magnetic moments of the electron, muon and tau lepton from first principles in twisted mass lattice QCD. With lattice data for multiple pion masses in the range 230 MeVanomalous magnetic moments from simulations directly at the physical value of the pion mass.

  4. Period Clustering of the Anomalous X-Ray Pulsars and Magnetic Field Decay in Magnetars.

    Science.gov (United States)

    Colpi; Geppert; Page

    2000-01-20

    We confront theoretical models for the rotational, magnetic, and thermal evolution of an ultramagnetized neutron star, or magnetar, with available data on the anomalous X-ray pulsars (AXPs). We argue that, if the AXPs are interpreted as magnetars, their clustering of spin periods between 6 and 12 s (observed at present in this class of objects), their period derivatives, their thermal X-ray luminosities, and the association of two of them with young supernova remnants can only be understood globally if the magnetic field in magnetars decays significantly on a timescale of the order of 104 yr.

  5. Anomalous Magnetohydrodynamics

    OpenAIRE

    Giovannini, Massimo

    2013-01-01

    Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy with charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved co...

  6. An upper limit on the anomalous magnetic moment of the $\\tau$ lepton

    CERN Document Server

    Ackerstaff, K; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Bartoldus, R; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bird, S D; Blobel, Volker; Bloodworth, Ian J; Bobinski, M; Bock, P; Bonacorsi, D; Boutemeur, M; Braibant, S; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Burgard, C; Bürgin, R; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Clarke, P E L; Cohen, I; Conboy, J E; Cooke, O C; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallapiccola, C; Dallavalle, G M; Davis, R; De Jong, S; del Pozo, L A; de Roeck, A; Desch, Klaus; Dienes, B; Dixit, M S; Doucet, M; Duchovni, E; Duckeck, G; Duerdoth, I P; Eatough, D; Estabrooks, P G; Etzion, E; Evans, H G; Evans, M; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Feld, L; Fiedler, F; Fierro, M; Fischer, H M; Fleck, I; Folman, R; Fong, D G; Foucher, M; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Geddes, N I; Geich-Gimbel, C; Geralis, T; Giacomelli, G; Giacomelli, P; Giacomelli, R; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Goodrick, M J; Gorn, W; Grandi, C; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Hargrove, C K; Hart, P A; Hartmann, C; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hillier, S J; Hobson, P R; Höcker, Andreas; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Hutchcroft, D E; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jawahery, A; Jeffreys, P W; Jeremie, H; Jimack, Martin Paul; Joly, A; Jones, C R; Jones, M; Jost, U; Jovanovic, P; Junk, T R; Kanzaki, J I; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kirk, J; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Koetke, D S; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kyberd, P; Lafferty, G D; Lahmann, R; Lai, W P; Lanske, D; Lauber, J; Lautenschlager, S R; Lawson, I; Layter, J G; Lazic, D; Lee, A M; Lefebvre, E; Lellouch, Daniel; Letts, J; Levinson, L; List, B; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mannelli, M; Marcellini, S; Markopoulos, C; Markus, C; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Menke, S; Merritt, F S; Mes, H; Meyer, J; Michelini, Aldo; Mikenberg, G; Miller, D J; Mincer, A; Mir, R; Mohr, W; Montanari, A; Mori, T; Mihara, S; Nagai, K; Nakamura, I; Neal, H A; Nellen, B; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oh, A; Oldershaw, N J; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, J L; Plane, D E; Poffenberger, P R; Poli, B; Posthaus, A; Rembser, C; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rooke, A M; Rossi, A M; Routenburg, P; Rozen, Y; Runge, K; Runólfsson, O; Ruppel, U; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharf, F; Scharff-Hansen, P; Schieck, J; Schleper, P; Schmitt, B; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Sieberg, R P B; Siroli, G P; Sittler, A; Skillman, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Springer, R W; Sproston, M; Stephens, K; Steuerer, J; Stockhausen, B; Stoll, K; Strom, D; Ströhmer, R; Szymanski, P; Tafirout, R; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomson, M A; Von Törne, E; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Ueda, I; Utzat, P; Van Kooten, R; Vannerem, P; Verzocchi, M; Vikas, P; Vokurka, E H; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D

    1998-01-01

    Using radiative Z^0 -> \\tau^+ \\tau^- \\gamma events collected with the OPAL detector at LEP at \\sqrt{s}=M_Z during 1990-95, a direct study of the electromagnetic current at the \\tau\\gamma vertex has been performed in terms of the anomalous magnetic form factor F_2 of the \\tau lepton. The analysis is based on a data sample of 1429 e^+ e^- -> \\tau^+ \\tau^- \\gamma events which are examined for a deviation from the expectation with F_2 = 0. From the non-observation of anomalous \\tau^+ \\tau^- \\gamma production a limit of -0.068 < F_2 < 0.065 is obtained. This can also be interpreted as a limit on the electric dipole form factor F_3 as -3.8 x 10^-16 e-cm < eF_3 < 3.6 x 10^-16 e-cm. The above ranges are valid at the 95% confidence level.

  7. Anomalous magnetic behavior for Mn-site doped La{sub 0.7}Ca{sub 0.3}MnO{sub 3}: internal magnetic interactions and extrinsic inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hong-guang, E-mail: hgzhang_njupt@hotmail.com [College of Science, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Li, Yong-tao [College of Science, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Xie, Liang [Department of Physical and Chemical Sciences, North China University of Technology, Beijing 100144 (China); Shi, Jiang-jian; Dong, Xue-guang; Ge, Xiao-peng; Liu, Hao [Physics Department, Southeast University, Nanjing 211189 (China); Li, Qi, E-mail: qli@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China)

    2015-11-01

    Magnetic properties of Mn-site doped La{sub 0.7}Ca{sub 0.3}Mn{sub 0.94}TM{sub 0.06}O{sub 3+Δ} (TM=Cu, Zn) were experimentally and theoretically studied. The low-temperature magnetization and magnetic phase transition temperature T{sub C} of the samples combining with simulations of 2D doped Ising model suggest that Cu{sup 2+} ions have an antiferromagnetic interaction with their nearest neighboring Mn ions. Interestingly, an anomalous magnetic behavior, a “step-like” magnetic phase transition, is observed. The existence and magnitude of this step vary with different doping ions and oxygen ratio, which is experimentally suggested to be relevant to the interaction between magnetic ions and oxygen content. A superposition between two independent magnetic systems with different values of an exchange integral J well explains the anomalous magnetic phase transition, which suggests that this step-like behavior results from extrinsic inhomogeneity and negligible coupling between grains in polycrystalline. - Highlights: • A “step-like” magnetic phase transition is observed in La{sub 0.7}Ca{sub 0.3}Mn{sub 0.94}TM{sub 0.06}O{sub 3}. • An anomalous magnetic property is experimentally and theoretically studied. • The evolution of T{sub C} and low T magnetization opposite to conventional behavior. • An antiferromagnetic interaction between Cu{sup 2+} and Mn ion is investigated by Ising model. • A linear superposition between magnetic behaviors explain the phase transition.

  8. Ageneral approach to first order phase transitions and the anomalous behavior of coexisting phases in the magnetic case.

    Energy Technology Data Exchange (ETDEWEB)

    Gama, S.; de Campos, A.; Coelho, A. A.; Alves, C. S.; Ren, Y.; Garcia, F.; Brown, D. E.; da Silva, L. M.; Magnus, A.; Carvalho, G.; Gandra, G. C.; dos Santos, A. O.; Cardoso, L. P.; von Ranke, P. J.; X-Ray Science Division; Univ. Federal de Sao Paulo; Unv. Estadual de Champinas; Univ. Estadual de Maringa Lab. Nacional de Luz Sincrotron; Northern Univ.; Univ. de Estado do Rio de Janerio

    2009-01-01

    First order phase transitions for materials with exotic properties are usually believed to happen at fixed values of the intensive parameters (such as pressure, temperature, etc.) characterizing their properties. It is also considered that the extensive properties of the phases (such as entropy, volume, etc.) have discontinuities at the transition point, but that for each phase the intensive parameters remain constant during the transition. These features are a hallmark for systems described by two thermodynamic degrees of freedom. In this work it is shown that first order phase transitions must be understood in the broader framework of thermodynamic systems described by three or more degrees of freedom. This means that the transitions occur along intervals of the intensive parameters, that the properties of the phases coexisting during the transition may show peculiar behaviors characteristic of each system, and that a generalized Clausius-Clapeyron equation must be obeyed. These features for the magnetic case are confirmed, and it is shown that experimental calorimetric data agree well with the magnetic Clausius-Clapeyron equation for MnAs. An estimate for the point in the temperature-field plane where the first order magnetic transition turns to a second order one is obtained (the critical parameters) for MnAs and Gd{sub 5}Ge{sub 2}Si{sub 2} compounds. Anomalous behavior of the volumes of the coexisting phases during the magnetic first order transition is measured, and it is shown that the anomalies for the individual phases are hidden in the behavior of the global properties as the volume.

  9. From magnetically doped topological insulator to the quantum anomalous Hall effect

    Institute of Scientific and Technical Information of China (English)

    He Ke; Ma Xu-Cun; Chen Xi; Lü Li; Wang Ya-Yu; Xue Qi-Kun

    2013-01-01

    Quantum Hall effect (QHE),as a class of quantum phenomena that occur in macroscopic scale,is one of the most important topics in condensed matter physics.It has long been expected that QHE may occur without Landau levels so that neither extemal magnetic field nor high sample mobility is required for its study and application.Such a QHE free of Landau levels,can appear in topological insulators (TIs) with ferromagnetism as the quantized version of the anomalous Hall effect,i.e.,quantum anomalous Hall (QAH) effect.Here we review our recent work on experimental realization of the QAH effect in magnetically doped TIs.With molecular beam epitaxy,we prepare thin films of Cr-doped (Bi,Sb)2Te3 TIs with wellcontrolled chemical potential and long-range ferromagnetic order that can survive the insulating phase.In such thin films,we eventually observed the quantization of the Hall resistance at h/e2 at zero field,accompanied by a considerable drop in the longitudinal resistance.Under a strong magnetic field,the longitudinal resistance vanishes,whereas the Hall resistance remains at the quantized value.The realization of the QAH effect provides a foundation for many other novel quantum phenomena predicted in TIs,and opens a route to practical applications of quantum Hall physics in low-power-consumption electronics.

  10. Influence of the electron's anomalous magnetic dipole moment on high-atomic number atoms

    International Nuclear Information System (INIS)

    Super heavy atoms ( Z > 100 ) are usually studied in the context of the so-called Quantum Electrodynamics of Strong Fields. In this theory the problem of the singularity in the electron energy whenever Z > 137 is overcome. This is done by considering the finite size of the nucleus and leads to interesting phenomena, such as the spontaneous production of positrons. Here, we show that, taking into account the contribution from the Anomalous Magnetic Dipole Moment of the electron ( by means of an effective theory ), within a point nucleus model, is a sufficient condition to obtain regular wave functions and physically acceptable energy values for Z > 137. (author)

  11. Charged spin half particle with anomalous magnetic moment in a plane wave field

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, Arvind Narayan [Universidade Federal do Rio de Janeiro, RJ (Brazil); Silva Filho, Pedro Barbosa da [Universidade Federal da Paraiba, Cajazeiras, PB (Brazil)

    2000-07-01

    Full text follows: The Dirac-Pauli equation for a charged spin half particle with anomalous magnetic moment in the presence of a plane wave external electromagnetic field is solved by an algebraic method and the solutions are shown to be simply related to the free particle ones.We also discuss the relationship of our results with the work of other authors. We show that our solutions are equivalent to those of Chakrabarti. We also show that the different results of Barut and Duru are in error. (author)

  12. Topcolour-assisted technicolour models and the muon anomalous magnetic moment

    International Nuclear Information System (INIS)

    We discuss and estimate the contributions of the new particles predicted by topcolour-assisted technicolour (TC2) models to the muon anomalous magnetic moment aμ. Our results show that the contributions of pseudo-Goldstone bosons are very small and can be safely ignored. The main contributions come from the ETC gauge boson xμ and topcolour gauge boson Z'. If we demand that the mass of Z' is consistent with other experimental constraints, its contributions are smaller than that of xμ. With reasonable values of the parameters in TC2 models, the observed BNL results for aμ could be explained. (author)

  13. Lattice Calculation of Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment

    CERN Document Server

    Blum, Thomas; Hayakawa, Masashi; Izubuchi, Taku; Jin, Luchang; Lehner, Christoph

    2016-01-01

    The quark-connected part of the hadronic light-by-light scattering contribution to the muon's anomalous magnetic moment is computed using lattice QCD with chiral fermions. We report several significant algorithmic improvements and demonstrate their effectiveness through specific calculations which show a reduction in statistical errors by more than an order of magnitude. The most realistic of these calculations is performed with a near-physical, $171$ MeV pion mass on a $(4.6\\;\\mathrm{fm})^3$ spatial volume using the $32^3\\times 64$ Iwasaki+DSDR gauge ensemble of the RBC/UKQCD Collaboration.

  14. Muon Anomalous Magnetic Moment and Gauge Symmetry in the Standard Model

    CERN Document Server

    Tsai, Er-Cheng

    2014-01-01

    No gauge invariant regularization is available for the perturbative calculation of the standard model. One has to add finite counter terms to restore gauge symmetry for the renormalized amplitudes. The muon anomalous magnetic moment can be accurately measured but the experimental result does not entirely agree with the theoretical calculation from the standard model. This paper is to compute the contributions to the muon gyromagnetic ratio $g_{\\mu}$ due to the finite counter terms. The result obtained is found to be far from sufficient to explain the discrepancy between theory and experiment.

  15. Inverted effective SUSY with combined Z' and gravity mediation, and muon anomalous magnetic moment

    OpenAIRE

    Kim, Jihn E.

    2012-01-01

    Effective supersymmetry(SUSY) where stop is the lightest squark may run into a two-loop tachyonic problem in some Z' mediation models. In addition, a large A term or/and a large stop mass are needed to have about a 126 GeV Higgs boson with three families of quarks and leptons. Thus, we suggest an inverted effective SUSY(IeffSUSY) where stop mass is larger compared to those of the first two families. In this case, it is possible to have a significant correction to the anomalous magnetic moment...

  16. Higgs mass and muon anomalous magnetic moment in the U(1) extended MSSM

    CERN Document Server

    Endo, Motoi; Iwamoto, Sho; Nakayama, Kazunori; Yokozaki, Norimi

    2011-01-01

    We study phenomenological aspects of the MSSM with extra U(1) gauge symmetry. We find that the lightest Higgs boson mass can be increased up to 125GeV without introducing a large SUSY scale or large A-terms, in the frameworks of the CMSSM and gauge mediated SUSY breaking (GMSB) models. This scenario can simultaneously explain the discrepancy of the muon anomalous magnetic moment (muon g-2) at the 1 sigma / 2 sigma level for U(1)-extended CMSSM / GMSB models. In the CMSSM case, the dark matter abundance can also be explained.

  17. N=2-Maxwell-Chern-Simons model with anomalous magnetic moment coupling via dimensional reduction

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, H.R.; Cunha, M.S.; Helayel Neto, Jose A.; Manssur, L.R.U; Nogueira, A.L.M.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Dept. de Campos e Particulas

    1998-02-01

    An N=1-supersymmetric version of the Cremmer-Scherk-Kalb-Ramond model with non-minimal coupling to matter is built up both in terms of superfields and in a component field formalism. By adopting a dimensional reduction procedure, the N=2-D=3 counterpart of the model comes out, with two main features: a genuine (diagonal) Chern-Simons term and an anomalous magnetic moment coupling between matter and the gauge potential. (author) 14 refs.; e-mail: hugo, macony, helayel, leon, nogue at cat.cbpf.br

  18. Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Mogi, M., E-mail: mogi@cmr.t.u-tokyo.ac.jp; Yoshimi, R.; Yasuda, K.; Kozuka, Y. [Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Tsukazaki, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075 (Japan); Takahashi, K. S. [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Kawasaki, M.; Tokura, Y. [Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-11-02

    Quantum anomalous Hall effect (QAHE), which generates dissipation-less edge current without external magnetic field, is observed in magnetic-ion doped topological insulators (TIs) such as Cr- and V-doped (Bi,Sb){sub 2}Te{sub 3}. The QAHE emerges when the Fermi level is inside the magnetically induced gap around the original Dirac point of the TI surface state. Although the size of gap is reported to be about 50 meV, the observable temperature of QAHE has been limited below 300 mK. We attempt magnetic-Cr modulation doping into topological insulator (Bi,Sb){sub 2}Te{sub 3} films to increase the observable temperature of QAHE. By introducing the rich-Cr-doped thin (1 nm) layers at the vicinity of both the surfaces based on non-Cr-doped (Bi,Sb){sub 2}Te{sub 3} films, we have succeeded in observing the QAHE up to 2 K. The improvement in the observable temperature achieved by this modulation-doping appears to be originating from the suppression of the disorder in the surface state interacting with the rich magnetic moments. Such a superlattice designing of the stabilized QAHE may pave a way to dissipation-less electronics based on the higher-temperature and zero magnetic-field quantum conduction.

  19. Anomalous magnetic orientations of magnetosome chains in a magnetotactic bacterium: Magnetovibrio blakemorei strain MV-1.

    Directory of Open Access Journals (Sweden)

    Samanbir S Kalirai

    Full Text Available There is a good deal of published evidence that indicates that all magnetosomes within a single cell of a magnetotactic bacterium are magnetically oriented in the same direction so that they form a single magnetic dipole believed to assist navigation of the cell to optimal environments for their growth and survival. Some cells of the cultured magnetotactic bacterium Magnetovibrio blakemorei strain MV-1 are known to have relatively wide gaps between groups of magnetosomes that do not seem to interfere with the larger, overall linear arrangement of the magnetosomes along the long axis of the cell. We determined the magnetic orientation of the magnetosomes in individual cells of this bacterium using Fe 2p X-ray magnetic circular dichroism (XMCD spectra measured with scanning transmission X-ray microscopy (STXM. We observed a significant number of cases in which there are sub-chains in a single cell, with spatial gaps between them, in which one or more sub-chains are magnetically polarized opposite to other sub-chains in the same cell. These occur with an estimated frequency of 4.0±0.2%, based on a sample size of 150 cells. We propose possible explanations for these anomalous cases which shed insight into the mechanisms of chain formation and magnetic alignment.

  20. Leading-order hadronic contributions to the lepton anomalous magnetic moments from the lattice

    CERN Document Server

    Burger, Florian; Jansen, Karl; Petschlies, Marcus; Pientka, Grit; Renner, Dru B

    2015-01-01

    The hadronic leading-order (hlo) contribution to the lepton anomalous magnetic moments $a_l^\\mathrm{hlo}$ of the Standard Model leptons still accounts for the dominant source of the uncertainty of the Standard Model estimates. We present the results of an investigation of the hadronic leading order anomalous magnetic moments of the electron, muon and tau lepton from first principles in twisted mass lattice QCD. With lattice data for multiple pion masses in the range $230 \\mathrm{~MeV} \\lesssim m_{PS} \\lesssim 490 \\mathrm{~MeV}$, multiple lattice volumes and three lattice spacings we perform the extrapolation to the continuum and to the physical pion mass and check for all systematic uncertainties in the lattice calculation. As a result we calculate $a_{l}^\\mathrm{hlo}$ for the three Standard Model leptons with controlled statistical and systematic error in agreement with phenomenological determinations using dispersion relations and experimental data. In addition, we also give a first estimate of the hadronic...

  1. Electron contribution to the muon anomalous magnetic moment at four loops

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Liu, Tao [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Smirnov, Alexander V. [Moscow State Univ. (Russian Federation). Scientific Research Computing Center; Smirnov, Vladimir A. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Steinhauser, Matthias [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik

    2016-02-15

    We present results for the QED contributions to the anomalous magnetic moment of the muon containing closed electron loops. The main focus is on perturbative corrections at four-loop order where the external photon couples to the external muon. Furthermore, all four-loop contributions involving simultaneously a closed electron and tau loop are computed. In combination with our recent results on the light-by-light-type corrections the complete four-loop electron-loop contribution to the anomalous magnetic moment of the muon has been obtained with an independent calculation. Our calculation is based on an asymptotic expansion in the ratio of the electron and the muon mass and shows the importance of higher order terms in this ratio. We perform a detailed comparison with results available in the literature and find good numerical agreement. As a by-product we present analytic results for the on-shell muon mass and wave function renormalization constants at three-loop order including massive closed electron and tau loops, which we also calculated using the method of asymptotic expansion.

  2. Magnetic excitations and anomalous spin-wave broadening in multiferroic FeV2O4

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang [Ames Laboratory; Ramazanoglu, Mehmet [Ames Laboratory; Chi, Songxue [Oak Ridge National Laboratory; Liu, Yong [Ames Laboratory; Lograsso, Thomas A. [Ames Laboratory; Vaknin, David [Ames Laboratory

    2014-06-01

    We report on the different roles of two orbital-active Fe2+ at the A site and V3+ at the B site in the magnetic excitations and on the anomalous spin-wave broadening in FeV2O4. FeV2O4 exhibits three structural transitions and successive paramagnetic (PM)–collinear ferrimagnetic (CFI)–noncollinear ferrimagnetic (NCFI)/ferroelectric transitions. The high-temperature tetragonal/PM–orthorhombic/CFI transition is accompanied by the appearance of a large energy gap in the magnetic excitations due to strong spin-orbit-coupling-induced anisotropy at the Fe2+ site. While there is no measurable increase in the energy gap from the orbital ordering of V3+ at the orthorhombic/CFI–tetragonal/NCFI transition, anomalous spin-wave broadening is observed in the orthorhombic/CFI state due to V3+ spin fluctuations at the B site. The spin-wave broadening is also observed at the zone boundary without softening in the NCFI/ferroelectric phase, which is discussed in terms of magnon-phonon coupling. Our study also indicates that the Fe2+ spins without the frustration at the A site may not play an important role in inducing ferroelectricity in the tetragonal/NCFI phase of FeV2O4.

  3. Series expansion of the photon self-energy in QED and the photon anomalous magnetic moment

    CERN Document Server

    Rojas, H Perez; Chavez, S Villalba

    2008-01-01

    We start from the analytical expression of the eigenvalues $\\kappa^{(i)}$ of the photon self-energy tensor in an external constant magnetic field $B$ calculated by Batalin Shabad in the Furry representation, and in the one-loop approximation. We expand in power series of the external field and in terms of the squared photon transverse momentum $z_2$ and (minus) transverse energy $z_1=k^2-z_2$, in terms of which are expressed $\\kappa^{(i)}$. A general expression is given for the photon anomalous magnetic moment $\\mu_{\\gamma}>0$ in the region of transparency, below the first threshold for pair creation, and it is shown that it is positive, i.e. paramagnetic. The results of the numerical calculation for $\\mu_{\\gamma}>0$ are displayed in a region close to the threshold.

  4. Quantum anomalous Hall effect in atomic crystal layers from in-plane magnetization

    Science.gov (United States)

    Ren, Yafei; Zeng, Junjie; Deng, Xinzhou; Yang, Fei; Pan, Hui; Qiao, Zhenhua

    2016-08-01

    We theoretically demonstrate that with in-plane magnetization, the quantum anomalous Hall effect (QAHE) can be realized in two-dimensional atomic crystal layers with preserved inversion symmetry but broken out-of-plane mirror reflection symmetry. By taking the honeycomb lattice system as an example, we find that the low-buckled structure satisfying the symmetry criteria is crucial to induce QAHE. The topologically nontrivial bulk gap carrying a Chern number of C =±1 opens in the vicinity of the saddle points M , where the band dispersion exhibits strong anisotropy. We further show that the QAHE with electrically tunable Chern number can be achieved in Bernal-stacked multilayer systems, and the applied interlayer potential differences can dramatically decrease the critical magnetization to make the QAHE experimentally feasible.

  5. Structural, magnetic and transport properties of Co2FeAl Heusler films with varying thickness

    Science.gov (United States)

    Wang, Xiaotian; Li, Yueqing; Du, Yin; Dai, Xuefang; Liu, Guodong; Liu, Enke; Liu, Zhongyuan; Wang, Wenhong; Wu, Guangheng

    2014-08-01

    We report on a systematic study of the structural, magnetic properties and the anomalous Hall effect, in the Heusler alloy Co2FeAl (CFA) epitaxial films on MgO (001), as a function of film thickness. It was found that the epitaxial CFA films show a highly ordered B2 structure with an in-plane uniaxial magnetic anisotropy. The electrical transport properties reveal that the lattice and magnon scattering contributions to the longitudinal resistivity. Independent on the thickness of films, the anomalous Hall resistivity of CFA films is found to be dominated by skew scattering only. Moreover, the anomalous Hall resistivity shows weakly temperature dependent behavior, and its absolute value increases as the thickness decreases. We attribute this temperature insensitivity in the anomalous Hall resistivity to the weak temperature dependent of tunneling spin-polarization in the CFA films, while the thickness dependence behavior is likely due to the increasing significance of interface or free surface electronic states.

  6. A magnetic reconnection mechanism for the generation of anomalous cosmic rays

    Science.gov (United States)

    Drake, James; Opher, Merav; Swisdak, Marc; Chamoun, Jacob

    The recent observations of the anomalous cosmic ray (ACR) energy spectrum as Voyagers 1 and 2 crossed the heliospheric termination shock have called into question the conventional shock source of these energetic particles. We suggest that the sectored heliospheric magnetic field, which results from the flapping of the heliospheric current sheet, piles up as it approaches the heliopause, narrowing the current sheets that separate the sectors and triggering the onset of collisionless magnetic reconnection. Particle-in-cell simulations reveal that the current layers break up into a turbulent bath of magnetic islands that merge to release a large fraction of the energy in the sectored magnetic field. Most of the magnetic energy goes into energetic ions with significant but smaller amounts of energy going into electrons. The dominant acceleration mechanism is through reflection in contracting islands, a first-order Fermi mechanism. Particle energy gain is regulated by the approach to the marginal firehose condition. The ACR differ-ential energy spectrum for all of the ion species takes the form of a power law with a spectral index slightly above 1.5, which is consistent with observations.

  7. Magnetic properties of hematite nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Hansen, Mikkel Fougt; Bender Koch, Christian;

    2000-01-01

    The magnetic properties of hematite (alpha-Fe2O3) particles with sizes of about 16 nm have been studied by use of Mossbauer spectroscopy, magnetization measurements, and neutron diffraction. The nanoparticles are weakly ferromagnetic at temperatures at least down to 5 K with a spontaneous...

  8. Relativistic energy correction of the hydrogen atom with an anomalous magnetic moment

    International Nuclear Information System (INIS)

    The electron is known to possess an anomalous magnetic moment, which interacts with the gradient of the electric field. This makes it necessary to compute its effects on the energy spectrum. Even though the Coulomb Dirac equation can be solved in closed form, this is no longer possible when the anomalous magnetic moment is included. In fact the interaction due to this term is so strong that it changes the domain of the Hamiltonian. From a differential equation point of view, the anomalous magnetic moment term is strongly singular near the origin. As usual, one has to resort to perturbation theory. This, however, only makes sense if the eigenvalues are stable. To prove stability is therefore a challenge one has to face before actually computing the energy shifts. The first stability results in this line were shown by Behncke for angular momenta κ≥3, because the eigenfunctions of the unperturbed Hamiltonian decay fast enough near the origin. He achieved this by decoupling the system and then using the techniques available for second order differential equations. Later, Kalf and Schmidt extended Behncke's results basing their analysis on the Pruefer angle technique and a comparison result for first order differential equations. The Pruefer angle method is particularly useful because it shows a better stability and because it obeys a first order differential equation. Nonetheless, Kalf and Schmidt had to exclude some coupling constants for κ>0. This I believe is an artefact of their method. In this study, I make increasing use of asymptotic integration, a method which is rather well adapted to perturbation theory and is known to give stability results to any level of accuracy. Together with the Pruefer angle technique, this lead to a more general stability result and even allows for an energy shifts estimate. Hamiltonians traditionally treated in physics to describe the spin-orbit effect are not self adjoint i.e. they are not proper observables in quantum

  9. Relativistic energy correction of the hydrogen atom with an anomalous magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Ambogo, David Otieno

    2015-07-15

    The electron is known to possess an anomalous magnetic moment, which interacts with the gradient of the electric field. This makes it necessary to compute its effects on the energy spectrum. Even though the Coulomb Dirac equation can be solved in closed form, this is no longer possible when the anomalous magnetic moment is included. In fact the interaction due to this term is so strong that it changes the domain of the Hamiltonian. From a differential equation point of view, the anomalous magnetic moment term is strongly singular near the origin. As usual, one has to resort to perturbation theory. This, however, only makes sense if the eigenvalues are stable. To prove stability is therefore a challenge one has to face before actually computing the energy shifts. The first stability results in this line were shown by Behncke for angular momenta κ≥3, because the eigenfunctions of the unperturbed Hamiltonian decay fast enough near the origin. He achieved this by decoupling the system and then using the techniques available for second order differential equations. Later, Kalf and Schmidt extended Behncke's results basing their analysis on the Pruefer angle technique and a comparison result for first order differential equations. The Pruefer angle method is particularly useful because it shows a better stability and because it obeys a first order differential equation. Nonetheless, Kalf and Schmidt had to exclude some coupling constants for κ>0. This I believe is an artefact of their method. In this study, I make increasing use of asymptotic integration, a method which is rather well adapted to perturbation theory and is known to give stability results to any level of accuracy. Together with the Pruefer angle technique, this lead to a more general stability result and even allows for an energy shifts estimate. Hamiltonians traditionally treated in physics to describe the spin-orbit effect are not self adjoint i.e. they are not proper observables in quantum

  10. Direct Evidence of Anomalous Interfacial Magnetization in Metamagnetic Pd doped FeRh Thin Films

    OpenAIRE

    Bennett, S. P.; Ambaye, H.; Lee, H.; LeClair, P.; Mankey, G. J.; Lauter, V.

    2015-01-01

    Palladium doped iron rhodium is a magnetic material of significant interest for it's close to room temperature magnetostructural phase transition from antiferromagnetic (AF) to ferromagnetic (FM) ordering. Here we report on the peculiarities of the magnetization distribution in thin films of FeRh(Pd) probed by Polarized Neutron Reflectometry. Remarkably, we've found thin interfacial regions with strong magnetization that have unique thermomagnetic properties as compared to the rest of the sys...

  11. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    OpenAIRE

    GROSU Marian C; LUPU Iuliana G; AVRAM Dorin; TUDORACHE Florin

    2015-01-01

    A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a sol...

  12. MeV scale leptonic force for cosmic neutrino spectrum and muon anomalous magnetic moment

    CERN Document Server

    Araki, Takeshi; Ota, Toshihiko; Sato, Joe; Shimomura, Takashi

    2015-01-01

    Characteristic patterns of cosmic neutrino spectrum reported by the IceCube collaboration and long-standing inconsistency between theory and experiment in muon anomalous magnetic moment are simultaneously explained by an extra leptonic force mediated by a gauge field with a mass of the MeV scale. With different assumptions for redshift distribution of cosmic neutrino sources, diffuse neutrino flux is calculated with the scattering between cosmic neutrino and cosmic neutrino background through the new leptonic force. Our analysis sheds light on a relation among lepton physics at the three different scales, PeV, MeV, and eV, and provides possible clues to the distribution of sources of cosmic neutrino and also to neutrino mass spectrum.

  13. Four-Flavour Leading Hadronic Contribution To The Muon Anomalous Magnetic Moment

    CERN Document Server

    Burger, Florian; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B

    2013-01-01

    We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, $a_{\\mu}^{\\rm hvp}$, arising from quark-connected Feynman graphs. It is based on ensembles featuring $N_f=2+1+1$ dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of $a_{\\mu}^{\\rm hvp}$. Our final result involving an estimate of the systematic uncertainty $$a_{\\mathrm{\\mu}}^{\\rm hvp} = 6.74(21)(18) \\cdot 10^{-8}$$ shows a good overall agreement with these computations.

  14. Electric and anomalous magnetic dipole moments of the muon in the MSSM

    International Nuclear Information System (INIS)

    We study the electric dipole moment (EDM) and the anomalous magnetic dipole moment (MDM) of the muon in the CP-violating Minimal Supersymmetric extension of the Standard Model (MSSM). We take into account the contributions from the chargino- and neutralino-mediated one-loop graphs and the dominant two-loop Higgs-mediated Barr-Zee diagrams. We improve earlier calculations by incorporating CP-violating Higgs-boson mixing effects and the resummed threshold corrections to the Yukawa couplings of the charged leptons as well as that of the bottom quark. The analytic correlation between the muon EDM and MDM is explicitly presented at one- and two-loop levels and, through several numerical examples, we illustrate its dependence on the source of the dominant contributions. We have implemented the analytic expressions for the muon EDM and MDM in an updated version of the public code CPsuperH2.0.

  15. Electric and anomalous magnetic dipole moments of the muon in the MSSM

    CERN Document Server

    Cheung, Kingman; Lee Jae Sik

    2009-01-01

    We study the electric dipole moment (EDM) and the anomalous magnetic dipole moment (MDM) of the muon in the CP-violating Minimal Supersymmetric extension of the Standard Model (MSSM). We take into account the contributions from the chargino- and neutralino-mediated one-loop graphs and the dominant two-loop Higgs-mediated Barr-Zee diagrams. We improve earlier calculations by incorporating CP-violating Higgs-boson mixing effects and the resummed threshold corrections to the Yukawa couplings of the charged leptons as well as that of the bottom quark. The analytic correlation between the muon EDM and MDM is explicitly presented at one- and two-loop levels and, through several numerical examples, we illustrate its dependence on the source of the dominant contributions. We have implemented the analytic expressions for the muon EDM and MDM in an updated version of the public code CPsuperH2.0.

  16. Four-flavour leading hadronic contribution to the muon anomalous magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Florian; Hotzel, Grit [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Feng, Xu [KEK National High Energy Physics, Tsukuba (Japan); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ. Nicosia (Cyprus). Dept. of Physics; Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus); Renner, Dru B. [Jefferson Lab, Newport News, VA (United States)

    2013-11-15

    We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, a{sup hvp}{sub {mu}}, arising from quark-connected Feynman graphs. It is based on ensembles featuring N{sub f}=2+1+1 dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of a{sup hvp}{sub {mu}}. Our final result involving an estimate of the systematic uncertainty a{sup hvp}{sub {mu}}=6.74(21)(18) x 10{sup -8} shows a good overall agreement with these computations.

  17. Hadronic contributions to the muon anomalous magnetic moment Workshop. $(g-2)_{\\mu}$: Quo vadis? Workshop. Mini proceedings

    CERN Document Server

    Benayoun, Maurice; Blum, Tom; Caprini, Irenel; Colangelo, Gilberto; Czyż, Henryk; Denig, Achim; Dominguez, Cesareo A; Eidelman, Simon; Fischer, Christian S; Gauzzi, Paolo; Guo, Yuping; Hafner, Andreas; Hayakawa, Masashi; Herdoiza, Gregorio; Hoferichter, Martin; Huang, Guangshun; Jansen, Karl; Jegerlehner, Fred; Kloss, Benedikt; Kubis, Bastian; Liu, Zhiqing; Marciano, William; Masjuan, Pere; Meyer, Harvey B; Mibe, Tsutomu; Nyffeler, Andreas; Pascalutsa, Vladimir; Pauk, Vladyslav; Pennington, Michael R; Peris, Santiago; Redmer, Christoph F; Sanchez-Puertas, Pablo; Shwartz, Boris; Solodov, Evgeny; Stoeckinger, Dominik; Teubner, Thomas; Unverzagt, Marc; Vanderhaeghen, Marc; Wolke, Magnus

    2014-01-01

    We present the mini-proceedings of the workshops Hadronic contributions to the muon anomalous magnetic moment: strategies for improvements of the accuracy of the theoretical prediction and $(g-2)_{\\mu}$: Quo vadis?, both held in Mainz from April 1$^{\\rm rst}$ to 5$^{\\rm th}$ and from April 7$^{\\rm th}$ to 10$^{\\rm th}$, 2014, respectively.

  18. Anomalous transport model study of chiral magnetic effects in heavy ion collisions

    Science.gov (United States)

    Sun, Yifeng; Ko, Che Ming; Li, Feng

    2016-10-01

    Using an anomalous transport model for massless quarks and antiquarks, we study the effect of a magnetic field on the elliptic flows of quarks and antiquarks in relativistic heavy ion collisions. With initial conditions from a blast wave model and assuming that the strong magnetic field produced in noncentral heavy ion collisions can last for a sufficiently long time, we obtain an appreciable electric quadrupole moment in the transverse plane of a heavy ion collision. The electric quadrupole moment subsequently leads to a splitting between the elliptic flows of quarks and antiquarks. The slope of the charge asymmetry dependence of the elliptic flow difference between positively and negatively charged particles is positive, which is expected from the chiral magnetic wave formed in the produced QGP and observed in experiments at the BNL Relativistic Heavy Ion Collider, only if the Lorentz force acting on the charged particles is neglected and the quark-antiquark scattering is assumed to be dominated by the chirality changing channel.

  19. Local magnetism in YbCrSb3, an anomalous member of the RECrSb3 series

    International Nuclear Information System (INIS)

    The intermetallic magnetic compound YbCrSb3, which shows anomalous behavior when compared to other compounds in the RECrSb3 series, is studied near zero magnetic field using μSR. Coherent muon spin precession is observed, unambiguously establishing at the local level that a significant fraction of the sample is in a well-ordered magnetic state below ∼240K. These results confirm, at the local level, that the magnetic transition temperature in YbCrSb3 is higher than those of the other RECrSb3 compounds synthesized to date.

  20. Avian magnetic compass can be tuned to anomalously low magnetic intensities.

    Science.gov (United States)

    Winklhofer, Michael; Dylda, Evelyn; Thalau, Peter; Wiltschko, Wolfgang; Wiltschko, Roswitha

    2013-07-22

    The avian magnetic compass works in a fairly narrow functional window around the intensity of the local geomagnetic field, but adjusts to intensities outside this range when birds experience these new intensities for a certain time. In the past, the geomagnetic field has often been much weaker than at present. To find out whether birds can obtain directional information from a weak magnetic field, we studied spontaneous orientation preferences of migratory robins in a 4 µT field (i.e. a field of less than 10 per cent of the local intensity of 47 µT). Birds can adjust to this low intensity: they turned out to be disoriented under 4 µT after a pre-exposure time of 8 h to 4 µT, but were able to orient in this field after a total exposure time of 17 h. This demonstrates a considerable plasticity of the avian magnetic compass. Orientation in the 4 µT field was not affected by local anaesthesia of the upper beak, but was disrupted by a radiofrequency magnetic field of 1.315 MHz, 480 nT, suggesting that a radical-pair mechanism still provides the directional information in the low magnetic field. This is in agreement with the idea that the avian magnetic compass may have developed already in the Mesozoic in the common ancestor of modern birds.

  1. Magnetic properties in the inhomogeneous chiral phase

    CERN Document Server

    Yoshiike, Ryo; Tatsumi, Toshitaka

    2016-01-01

    We investigate the magnetic properties of quark matter in the inhomogeneous chiral phase, where both scalar and pseudoscalar condensates spatially modulate. The energy spectrum of the lowest Landau level becomes asymmetric about zero in the external magnetic field, and gives rise to the remarkably magnetic properties: quark matter has a spontaneous magnetization, while the magnetic susceptibility does not diverge on the critical point.

  2. Magnetic Properties and Intergranular Action in Bonded Hybrid Magnets

    Institute of Scientific and Technical Information of China (English)

    Hua Zhenghe; Li Shandong; Han Zhida; Wang Dunhui; Zhong Wei; Gu Benxi; Lu Mu; Zhang Jianrong; Du Youwei

    2007-01-01

    Magnetic properties and intergranular action in bonded hybrid magnets, based on NdFeB and strontium ferrite powders were investigated. The long-range magnetostatic interaction and short-range exchange coupling interaction existed simultaneously in bonded hybrid magnets, and neither of them could be neglected. Some magnetic property parameters of hybrid magnets could be approximately obtained by adding the hysteresis loops of two magnets pro rata.

  3. Anomalous D'yakonov-Perel' spin relaxation in semiconductor quantum wells under a strong magnetic field in the Voigt configuration

    Science.gov (United States)

    Zhou, Y.; Yu, T.; Wu, M. W.

    2013-06-01

    We report an anomalous scaling of the D’yakonov-Perel’ spin relaxation with the momentum relaxation in semiconductor quantum wells under a strong magnetic field in the Voigt configuration. We focus on the case in which the external magnetic field is perpendicular to the spin-orbit-coupling-induced effective magnetic field and its magnitude is much larger than the latter one. It is found that the longitudinal spin relaxation time is proportional to the momentum relaxation time even in the strong-scattering limit, indicating that the D’yakonov-Perel’ spin relaxation demonstrates Elliott-Yafet-like behavior. Moreover, the transverse spin relaxation time is proportional (inversely proportional) to the momentum relaxation time in the strong- (weak-) scattering limit, both in the opposite trends against the well-established conventional D’yakonov-Perel’ spin relaxation behaviors. We further demonstrate that all the above anomalous scaling relations come from the unique form of the effective inhomogeneous broadening.

  4. Muon anomalous magnetic moment in a $SU(4) \\otimes U(1)_N$ model without exotic electric charges

    CERN Document Server

    Cogollo, D

    2014-01-01

    We study an electroweak gauge extension of the standard model, so called 3-4-1 model, which does not contain exotic electric charges and it is anomaly free. We discuss phenomenological constraints of the model and compute all the corrections to the muon magnetic moment. Mainly, we discuss different mass regimes and their impact on this correction, deriving for the first time direct limits on the masses of the neutral fermions and charged vector bosons. Interestingly, the model could address the reported muon anomalous magnetic moment excess, however it would demands a rather low scale of symmetry breaking, far below the current electroweak constraints on the model. Thus, if this excess is confirmed in the foreseeable future by the g-2 experiment at FERMILAB, this 3-4-1 model can be decisively ruled out since the model cannot reproduce a sizeable and positive contribution to the muon anomalous magnetic moment consistent with current electroweak limits.

  5. Experimental Demonstration of Anomalous Field Enhancement in All-Dielectric Transition Magnetic Metamaterials.

    Science.gov (United States)

    Sun, Jingbo; Liu, Xiaoming; Zhou, Ji; Kudyshev, Zhaxylyk; Litchinitser, Natalia M

    2015-11-04

    Anomalous field enhancement accompanied by resonant absorption phenomenon was originally discussed in the context of plasma physics and in applications related to radio-communications between the ground and spacecraft returning to Earth. Indeed, there is a critical period of time when all communications are lost due to the reflection/absorption of electromagnetic waves by the sheath of plasma created by a high speed vehicle re-entering the atmosphere. While detailed experimental studies of these phenomena in space are challenging, the emergence of electromagnetic metamaterials enables researchers exceptional flexibility to study them in the laboratory environment. Here, we experimentally demonstrated the strong localized field enhancement of magnetic field for an electromagnetic wave propagating in Mie-resonance-based inhomogeneous metamaterials with magnetic permeability gradually changing from positive to negative values. Although these experiments were performed in the microwave frequency range, the proposed all-dielectric approach to transition metamaterials can be extended to terahertz, infrared, and visible frequencies. We anticipate that these results, besides most basic science aspects, hold the potential for numerous applications, including low-intensity nonlinear transformation optics, topological photonics, and the broader area of surface and interface science.

  6. Anomalous Hall effect sensors based on magnetic element doped topological insulator thin films

    Science.gov (United States)

    Ni, Yan; Zhang, Zhen; Nlebedim, Ikenna; Jiles, David

    Anomalous Hall effect (AHE) is recently discovered in magnetic element doped topological insulators (TIs), which promises low power consumption highly efficient spintronics and electronics. This discovery broaden the family of Hall effect (HE) sensors. In this work, both HE and AHE sensor based on Mn and Cr doped Bi2Te3 TI thin films will be systematically studied. The influence of Mn concentration on sensitivity of MnxBi2-xTe3 HE sensors will be discussed. The Hall sensitivity increase 8 times caused by quantum AHE will be reported. AHE senor based on Cr-doped Bi2Te3 TI thin films will also be studied and compared with Mn doped Bi2Te3 AHE sensor. The influence of thickness on sensitivity of CrxBi2-xTe3 AHE sensors will be discussed. Ultrahigh Hall sensitivity is obtained in Cr doped Bi2Te3. The largest Hall sensitivity can reach 2620 Ω/T in sensor which is almost twice higher than that of the normal semiconductor HE sensor. Our work indicates that magnetic element doped topological insulator with AHE are good candidates for ultra-sensitive Hall effect sensors.

  7. A fractal derivative model for the characterization of anomalous diffusion in magnetic resonance imaging

    Science.gov (United States)

    Liang, Yingjie; Ye, Allen Q.; Chen, Wen; Gatto, Rodolfo G.; Colon-Perez, Luis; Mareci, Thomas H.; Magin, Richard L.

    2016-10-01

    Non-Gaussian (anomalous) diffusion is wide spread in biological tissues where its effects modulate chemical reactions and membrane transport. When viewed using magnetic resonance imaging (MRI), anomalous diffusion is characterized by a persistent or 'long tail' behavior in the decay of the diffusion signal. Recent MRI studies have used the fractional derivative to describe diffusion dynamics in normal and post-mortem tissue by connecting the order of the derivative with changes in tissue composition, structure and complexity. In this study we consider an alternative approach by introducing fractal time and space derivatives into Fick's second law of diffusion. This provides a more natural way to link sub-voxel tissue composition with the observed MRI diffusion signal decay following the application of a diffusion-sensitive pulse sequence. Unlike previous studies using fractional order derivatives, here the fractal derivative order is directly connected to the Hausdorff fractal dimension of the diffusion trajectory. The result is a simpler, computationally faster, and more direct way to incorporate tissue complexity and microstructure into the diffusional dynamics. Furthermore, the results are readily expressed in terms of spectral entropy, which provides a quantitative measure of the overall complexity of the heterogeneous and multi-scale structure of biological tissues. As an example, we apply this new model for the characterization of diffusion in fixed samples of the mouse brain. These results are compared with those obtained using the mono-exponential, the stretched exponential, the fractional derivative, and the diffusion kurtosis models. Overall, we find that the order of the fractal time derivative, the diffusion coefficient, and the spectral entropy are potential biomarkers to differentiate between the microstructure of white and gray matter. In addition, we note that the fractal derivative model has practical advantages over the existing models from the

  8. A Study of Neutron Star Structure in Strong Magnetic Fields that includes Anomalous Magnetic Moments

    Institute of Scientific and Technical Information of China (English)

    Guang-Jun Mao; Akira Iwamoto; Zhu-Xia Li

    2003-01-01

    We study the effect of strong magnetic fields on the structure of neutronstar. We find that if the interior field is on the same order as the surface fieldcurrently observed, then the influences of the field on the star's mass and radius arenegligible; if the field is as large as that estimated from the scalar virial theorem,then considerable effects will be induced. The maximum mass of the star will beincreased substantially while the central density is greatly reduced. The radius ofa magnetic star can be larger by about 10% ~ 20% than a nonmagnetic star of thesame mass.

  9. Nonlocal Anomalous Hall Effect

    Science.gov (United States)

    Zhang, Steven S.-L.; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect—the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt /YIG structures.

  10. Nonlocal Anomalous Hall Effect.

    Science.gov (United States)

    Zhang, Steven S-L; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect-the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt/YIG structures.

  11. Emerging magnetism and anomalous Hall effect in iridate–manganite heterostructures

    Science.gov (United States)

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L.; Freeland, John W.; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R.; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z.; Eres, Gyula; Fitzsimmons, Michael R.; Lee, Ho Nyung

    2016-01-01

    Strong Coulomb repulsion and spin–orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin–orbit entangled 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials. PMID:27596572

  12. Emerging magnetism and anomalous Hall effect in iridate-manganite heterostructures

    Science.gov (United States)

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L.; Freeland, John W.; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R.; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z.; Eres, Gyula; Fitzsimmons, Michael R.; Lee, Ho Nyung

    2016-09-01

    Strong Coulomb repulsion and spin-orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin-orbit entangled 3d-5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.

  13. Magnetic Properties of Erbium Gallium Gallate under High Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    Zhang Xijuan; Cheng Haiying; Yang Cuihong; Wang Wei

    2004-01-01

    A theoretical investigation on the magnetic properties of rare-earth Er3+ in Er3 Ga5 O12 was reported. The average magnetic moments(M) for applied magnetic field H parallel to the [001 ], [ 100], [ 110], [ 111 ] direction was studied based on the quantum theory. Temperature dependence of the magnetic properties is analyzed for H applied parallel to the [ 100] and [ 111 ] crystallographic directions. The magnetization decreases with increasing temperature,showing good agreement with thermal effect. A strong anisotropy of the magnetization is found under high magnetic field, but when the magnetic field is small, M and H are proportional.

  14. Modulated magnetism and anomalous electronic transport in Ce3Cu4As4O2

    Science.gov (United States)

    Wang, Jiakui K.; Wu, Shan; Qiu, Yiming; Rodriguez-Rivera, Jose A.; Huang, Qingzhen; Broholm, C.; Morosan, E.

    2016-08-01

    The complex magnetism and transport properties of tetragonal Ce3Cu4As4O2 were examined through neutron scattering and physical property measurements on polycrystalline samples. The lamellar structure consists of alternating layers of CeCu4As4 with a single square Ce lattice and Ce2O2 bilayers. Peaks in the specific heat at the Néel temperature TN=24 K, T2=16 K, and T3=1.9 K indicate three magnetic phase transitions or distinct crossover phenomena. For T wave vector k1=c* . For T wave vector. T3 marks a spin-flop transition where the k1 staggered magnetization switches to in-plane polarization. There are significant transport anomalies associated with the transitions, in particular a substantial reduction in resistivity for T saturation magnetization achieved for μ0H =7 T at T =2 K. We trace the unusual sequence of magnetic transitions to competing interactions and anisotropies in the alternating quasi-two-dimensional magnetic layers.

  15. A to Z of the muon anomalous magnetic moment in the MSSM with Pati-Salam at the GUT scale

    Science.gov (United States)

    Belyaev, Alexander S.; Camargo-Molina, José E.; King, Steve F.; Miller, David J.; Morais, António P.; Schaefers, Patrick B.

    2016-06-01

    We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an A 4 × Z 5 family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass m 0 and three right-handed soft masses m 1 , m 2 , m 3, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon ( g - 2) μ . Since about two decades, ( g - 2) μ suffers a puzzling about 3 σ excessoftheexperimentallymeasuredvalueoverthetheoreticalprediction,whichour model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potentially explain di-lepton excesses observed by CMS and ATLAS.

  16. A to Z of the Muon Anomalous Magnetic Moment in the MSSM with Pati-Salam at the GUT scale

    CERN Document Server

    Belyaev, Alexander S; King, Steve F; Miller, David J; Morais, António P; Schaefers, Patrick B

    2016-01-01

    We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an $A_4 \\times Z_5$ family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass $m_0$ and three right-handed soft masses $m_1,m_2,m_3$, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon $(g-2)_\\mu$. Since about two decades, $(g-2)_\\mu$ suffers a puzzling about 3$\\,\\sigma$ excess of the experimentally measured value over the theoretical prediction, which our model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potent...

  17. Evidence of local effects in anomalous refraction and focusing properties of dodecagonal photonic quasicrystals

    CERN Document Server

    Di Gennaro, Emiliano; Savo, Salvatore; Andreone, Antonello; Morello, Davide; Galdi, Vincenzo; Castaldi, Giuseppe; Pierro, Vincenzo

    2008-01-01

    We present the key results from a comprehensive study of the refraction and focusing properties of a two-dimensional dodecagonal photonic ``quasicrystal'' (PQC), carried out via both full-wave numerical simulations and microwave measurements on a slab made of alumina rods inserted in a parallel-plate waveguide. We observe anomalous refraction and focusing in several frequency regions, confirming some recently published results. However, our interpretation, based on numerical and experimental evidence, differs substantially from the one in terms of ``effective negative refractive-index'' that was originally proposed. Instead, our study highlights the critical role played by short-range interactions associated with local order and symmetry.

  18. Anomalous behaviour of thermophysical properties of stoichiometric uranium dioxide by molecular dynamics simulation

    International Nuclear Information System (INIS)

    We present a classical molecular dynamics simulation of uranium dioxide in the temperature range of 300-3000 K. Temperature dependences of thermal conductivity, heat capacity and ionic conductivity are investigated. Our study shows the rise of thermal conductivity of uranium dioxide at very high temperatures (above 2500 K), which is not predicted by the former anharmonic theories. Several pair potentials are used in the simulation, and they depict similar effects. Long range forces are accounted by Ewald sums. Static thermal properties are evaluated in NPT ensemble. It is shown that a high-temperature peak on heat capacity is present and is more legible in large systems. To ensure the best reliability, transport properties are evaluated using the theory of autocorrelation functions in NVE ensemble. In order to properly define thermal conductivity in ionic systems with charge fluxes, an expression which accounts the thermoelectric effect is derived from Onsager reciprocal relations. The rise on temperature dependence of thermal conductivity is accompanied by the peak on heat capacity and an anomalous rise of ionic conductivity. However, it is shown that there is no partial melting of the oxygen sublattice, which suggests that the system does not necessarily exhibit a superionic transition. Instead, kick-out diffusion in oxygen sublattice is proposed to be the origin of such anomalous behavior of thermophysical properties. (author)

  19. Low-Temperature Magnetic Properties of Co Antidot Array

    Institute of Scientific and Technical Information of China (English)

    LIU Qing-Fang; JIANG Chang-Jun; FAN Xiao-Long; WANG Jian-Bo; XUE De-Sheng

    2006-01-01

    Cobalt antidot arrays with different thicknesses are fabricated by rf magnetron sputtering onto porous alumina substrates. Scanning electron microscopy and grazing incidence x-ray diffraction are employed to characterize the morphology and crystal structure of the antidot array, respectively. The temperature dependence of magnetic properties shows that in the temperature range 5K-300K, coercivity and squareness increase firstly, reach their maximum values, then decrease. The anomalous temperature dependences of coercivity and squareness are discussed by considering the pinning effect of the antidot and the magnetocrystalline anisotropy.

  20. A Call for New Physics : The Muon Anomalous Magnetic Moment and Lepton Flavor Violation

    CERN Document Server

    Lindner, Manfred; Queiroz, Farinaldo S

    2016-01-01

    We review how the muon anomalous magnetic moment ($g-2$) and the quest for lepton flavor violation are intimately correlated. Indeed the decay $\\mu \\to e \\gamma$ is induced by the same amplitude for different choices of in- and outgoing leptons. In this work, we try to address some intriguing questions such as: Which hierarchy in the charged lepton sector one should have in order to reconcile possible signals coming simultaneously from $g-2$ and LFV? What can we learn if the $g-2$ anomaly is confirmed by the upcoming flagship experiments at FERMILAB and J-PARC, and no signal is seen in the decay $\\mu \\rightarrow e\\gamma$ in the foreseeable future? On the other hand, if the $\\mu \\rightarrow e\\gamma$ decay is seen in the upcoming years, do we need to necessarily observe a signal also in $g-2$? In this attempt, we generally study the correlation between the two phenomena in a detailed analysis of simplified models. We derive master integrals and fully analytical and exact expressions for both phenomena. We inves...

  1. Tests of hadronic vacuum polarization fits for the muon anomalous magnetic moment

    CERN Document Server

    Golterman, Maarten; Peris, Santiago

    2013-01-01

    We construct a physically motivated model for the isospin-one non-strange vacuum polarization function Pi(Q^2) based on a spectral function given by vector-channel OPAL data from hadronic tau decays for energies below the tau mass and a successful parametrization, employing perturbation theory and a model for quark-hadron duality violations, for higher energies. Using a covariance matrix and Q^2 values from a recent lattice simulation, we then generate fake data for Pi(Q^2) and use it to test fitting methods currently employed on the lattice for extracting the hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This comparison reveals a systematic error much larger than the few-percent total error sometimes claimed for such extractions in the literature. In particular, we find that errors deduced from fits using a Vector Meson Dominance ansatz are misleading, typically turning out to be much smaller than the actual discrepancy between the fit and exact model results. The use of a ...

  2. Tests of hadronic vacuum polarization fits for the muon anomalous magnetic moment

    CERN Document Server

    Golterman, Maarten; Peris, Santiago

    2013-01-01

    Using experimental spectral data for hadronic tau decays from the OPAL experiment, supplemented by a phenomenologically successful parameterization for the high-s region not covered by the data, we construct a physically constrained model of the isospin-one vector-channel polarization function. Having such a model as a function of Euclidean momentum Q^2 allows us to explore the systematic error associated with fits to the Q^2 dependence of lattice data for the hadronic electromagnetic current polarization function which have been used in attempts to compute the leading order hadronic contribution, a_\\mu^HLO, to the muon anomalous magnetic moment. In contrast to recent claims made in the literature, we find that a final error in this quantity of the order of a few percent does not appear possible with current lattice data, given the present lack of precision in the determination of the vacuum polarization at low Q^2. We also find that fits to the vacuum polarization using fit functions based on Vector Meson Do...

  3. New evaluation of hadronic contributions to the anomalous magnetic moment of charged leptons

    International Nuclear Information System (INIS)

    A re-evaluation of the lowest-order hagronic vacuum-polarization contribution to the anomalous magnetic moment of the electron, muon and tau-lepton with a higher precision in comparison with previous estimates is carried out. The latter is achieved because new data on some exclusive processes have appeared recently, more accomplished models for a description of the pion and kaon electromagnetic structure have been developed and the revised (due to a new value of the coefficient of the third power of αs) QCD formula for R=σtot (e+e-→had)/σtot (e+e-→μ+μ-) with electroweak corrections has been applied to analyze all existing data in a proper way. The final results are ae(2)had=(1.810±0.011±0.002)x10-12 aμ(2)had=(6.986±0.042±0.016)x10-8 and aτ(2)had=(3.436±0.024±0.024)x10-6. 19 refs.; 2 figs.; 3 tabs

  4. Anomalous results observed in magnetization of bulk high temperature superconductors—A windfall for applications

    Science.gov (United States)

    Weinstein, Roy; Parks, Drew; Sawh, Ravi-Persad; Carpenter, Keith; Davey, Kent

    2016-04-01

    Recent experiments on pulsed-zero field cool magnetization of bulk high Jc YBCO (YBa2Cu3O7-δ) have shown unexpected results. For example, reproducible, non-destructive, rapid, giant field leaps (GFLs) to higher penetrated field are observed. The observations are inconsistent with the critical state model (CSM), in several aspects. Additional experiments have been pursued in an attempt to clarify the physics involved in the observed anomalies. Here, we present experimental results for the Jc dependence of the anomalous features. It is found that the sudden field increase in the GFL is a monotonically increasing function of Jc. The ratio of required pulsed field amplitude, BA,max, to obtain maximum trappable field, BT,max, which CSM predicts to be ≥2.0, gradually approaches 1.0 at high Jc. Tests using values of pulsed, applied field BA,max just below the GFL exhibit two additional anomalies: (i) At high Jc, the highest trapped field is up to ˜6 times lower than predicted by CSM, and (ii) the measured Lorentz force as a function of Jc deviates sharply from CSM predictions. The data rule out heating effects and pinning center geometry as possible physical causes of these anomalies. A speculative cause is considered.

  5. Dissipation of the sectored heliospheric magnetic field near the heliopause: a mechanism for the generation of anomalous cosmic rays

    CERN Document Server

    Drake, J F; Swisdak, M; Chamoun, J N

    2009-01-01

    The recent observations of the anomalous cosmic ray (ACR) energy spectrum as Voyagers 1 and 2 crossed the heliospheric termination shock have called into question the conventional shock source of these energetic particles. We suggest that the sectored heliospheric magnetic field, which results from the flapping of the heliospheric current sheet, piles up as it approaches the heliopause, narrowing the current sheets that separate the sectors and triggering the onset of collisionless magnetic reconnection. Particle-in-cell simulations reveal that most of the magnetic energy is released and most of this energy goes into energetic ions with significant but smaller amounts of energy going into electrons. The energy gain of the most energetic ions results from their reflection from the ends of contracting magnetic islands, a first order Fermi process. The energy gain of the ions in contracting islands increases their parallel (to the magnetic field ${\\bf B}$) pressure $p_\\parallel$ until the marginal firehose condi...

  6. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived and the...... generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....

  7. The magnetic properties of the hollow cylindrical ideal remanence magnet

    CERN Document Server

    Bjørk, R

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown to generate a field exactly twice as large as the equivalent ideal remanence magnet.

  8. Anomalous electrical properties of Au/SrTiO3 interface

    Science.gov (United States)

    Xu, Lun; Yajima, Takeaki; Nishimura, Tomonori; Toriumi, Akira

    2016-08-01

    Metal/dielectric interface properties of Au/SrTiO3 (STO) and SrRuO3/SrTiO3 (SRO/STO) interfaces were investigated using metal/STO/heavily Nb-doped STO (0.5 wt % Nb:STO) capacitors. The observed interfacial capacitance at SRO/STO accords with results predicted theoretically, whereas that at the Au/STO interface is strongly suppressed, suggesting an intrinsic low-k (dielectric constant) interfacial layer formation at the Au/STO interface owing to in situ evaporated Au after STO film deposition. Furthermore, metal/0.01 wt % Nb:STO junctions were also analyzed. It was found that the SRO/Nb:STO junction forms an ideal Schottky dipole, whereas the Au/Nb:STO junction exhibits anomalous electrical properties.

  9. Direct evidence of anomalous interfacial magnetization in metamagnetic Pd doped FeRh thin films.

    Science.gov (United States)

    Bennett, S P; Ambaye, H; Lee, H; LeClair, P; Mankey, G J; Lauter, V

    2015-01-01

    Palladium doped iron rhodium is a magnetic material of significant interest for it's close to room temperature magnetostructural phase transition from antiferromagnetic (AF) to ferromagnetic (FM) ordering. Here we report on the peculiarities of the magnetization distribution in thin films of FeRh(Pd) probed by Polarized Neutron Reflectometry. Remarkably, we've found thin interfacial regions with strong magnetization that have unique thermomagnetic properties as compared to the rest of the system. These regions exist at the top and bottom interfaces of the films while the central regions behave similarly to the bulk with a clear AF-FM order transition. Further we explore the impact of an additional Pt interlayer introduced in the middle of the FeRh(Pd) film and reveal that it serves to replicate the strong interfacial magnetization found at the top and bottom interfaces. These results are of great value both in understanding the fundamental physics of such an order transition, and in considering FeRh(Pd) for magnetic media and spintronics applications. PMID:25771919

  10. Effects of magnetic field on fluidization properties of magnetic pearls

    Institute of Scientific and Technical Information of China (English)

    Maoming; Fan; Zhenfu; Luo; Yuemin; Zhao; Qingru; Chen; Daniel; Tao; Xiuxiang; Tao; Zhenqiang; Chen

    2007-01-01

    An experimental study of the influence of external magnetic field on the fluidization behavior of magnetic pearls was carried out. Magnetic pearls are a magnetic form of iron oxide that mainly consists of Fe2O3 which are recovered from a high-volume power plant fly ash from pulverized coal combustion. Due to its abundance, low price and particular physical and chemical properties, magnetic pearls can be used as a heavy medium for minerals or solid waste dry separation based on density difference. This paper introduces the properties of magnetic pearls and compares the performance of magnetic pearls fluidised bed operation with or without an external magnetic field. Experimental results show that an external magnetic field significantly improves the fluidization performance of magnetic pearls such as uniformity and stability.

  11. The activity and radial dependence of anomalous diffusion by pitch angle scattering on split magnetic drift shells

    Science.gov (United States)

    O'Brien, T. P.

    2015-01-01

    in the magnetospheric magnetic field produce drift shell splitting, which causes the radial (drift shell) invariant to sometimes depend on pitch angle. Where drift shell splitting is significant, pitch angle scattering leads to diffusion in all three invariants of the particle's motion, including cross diffusion. We examine the magnitude of drift shell splitting-related anomalous diffusion for outer zone electrons compared to conventional diffusion in the absence of drift shell splitting. We assume that the primary local scattering process is wave-particle interactions with chorus. We find that anomalous radial diffusion can exceed that of conventional drift-resonant radial diffusion for particles with energies near 0.1 MeV at all radial distances outside the plasmasphere during quiet to moderate geomagnetic activity, and it is significant at 0.5 MeV. Cross diffusion involving the radial invariant can exceed the geometric mean of the corresponding pure diffusion coefficients at 0.1 MeV, and that such cross diffusion is significant even at 0.5-1 MeV. At 1 MeV, cross diffusion is often significant. The highest radial distances and magnetic activity levels in our study do not always exhibit as much significant anomalous diffusion as moderate radial distances and activity levels. This can be explained by (a) stronger dependence of conventional diffusion on magnetic activity and radius, and (b) strongest drift shell splitting at moderate magnetic activity. Simulation codes that neglect the possibility for cross terms will likely systematically underperform, especially for 0.1-0.5 MeV electrons, for much of the outer zone for quiet to moderate levels of magnetic activity.

  12. Magnetic materials fundamentals, products, properties, applications

    CERN Document Server

    Hilzinger, Rainer

    2013-01-01

    At a practical level, this compendium reviews the basics of soft and hard magnetic materials, discusses the advantages of the different processing routes for the exploitation of the magnetic properties and hence assists in proper, fail-safe and economic application of magnetic materials. Essential guidelines and formulas for the calculation of the magnetic and electrical properties, temperature and long-term stability of permanent magnets, of inductive components and magnetic shielding are compiled. Selected fields of application and case studies illustrate the large diversity of technical applications. Application engineers will appreciate the comprehensive compilation of the properties and detailed characteristic curves of modern soft and hard magnetic materials. Materials scientists will enjoy the presentation of the different processing routes and their impact on the magnetic properties and students will profit from the survey from the basics of magnetism down to the applications in inductive components, ...

  13. Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

    2009-08-21

    In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

  14. Room-temperature anomalous Hall effect and magnetroresistance in (Ga, Co)-codoped ZnO diluted magnetic semiconductor films

    Institute of Scientific and Technical Information of China (English)

    Liu Xue-Chao; Chen Zhi-Zhan; Shi Er-Wei; Liao Da-Qian; Zhou Ke-Jin

    2011-01-01

    This paper reports that the (Ga, Co)-codoped ZnO thin films have been grown by inductively coupled plasma enhanced physical vapour deposition. Room-temperature ferromagnetism is observed for the as-grown thin films. The x-ray absorption fine structure characterization reveals that Co2+ and Ga3+ ions substitute for Zn2+ ions in the ZnO lattice and exclude the possibility of extrinsic ferromagnetism origin. The ferromagnetic (Ga, Co)-codoped ZnO thin films exhibit carrier concentration dependent anomalous Hall effect and positive magnetoresistance at room temperature. The mechanism of anomalous Hall effect and magneto-transport in ferromagnetic ZnO-based diluted magnetic semiconductors is discussed.

  15. Modeling Magnetic Properties in EZTB

    Science.gov (United States)

    Lee, Seungwon; vonAllmen, Paul

    2007-01-01

    A software module that calculates magnetic properties of a semiconducting material has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure. [EZTB is designed to model the electronic structures of semiconductor devices ranging from bulk semiconductors, to quantum wells, quantum wires, and quantum dots. EZTB implements an empirical tight-binding mathematical model of the underlying physics.] This module can model the effect of a magnetic field applied along any direction and does not require any adjustment of model parameters. The module has thus far been applied to study the performances of silicon-based quantum computers in the presence of magnetic fields and of miscut angles in quantum wells. The module is expected to assist experimentalists in fabricating a spin qubit in a Si/SiGe quantum dot. This software can be executed in almost any Unix operating system, utilizes parallel computing, can be run as a Web-portal application program. The module has been validated by comparison of its predictions with experimental data available in the literature.

  16. Evidence of local effects in anomalous refraction and focusing properties of dodecagonal photonic quasicrystals

    Science.gov (United States)

    di Gennaro, Emiliano; Miletto, Carlo; Savo, Salvatore; Andreone, Antonello; Morello, Davide; Galdi, Vincenzo; Castaldi, Giuseppe; Pierro, Vincenzo

    2008-05-01

    We present the key results from a comprehensive study of the refraction and focusing properties of a two-dimensional dodecagonal photonic “quasicrystal” (PQC), which was carried out via both full-wave numerical simulations and microwave measurements on a slab made of alumina rods inserted in a parallel-plate waveguide. We observe an anomalous refraction and focusing in several frequency regions, which confirm some recently published results. However, our interpretation, which is based on numerical and experimental evidence, substantially differs from the one in terms of “effective negative refractive index” that was originally proposed. Instead, our study highlights the critical role played by short-range interactions associated with local order and symmetry.

  17. Magnetic Properties of Magnetic Nanoparticles for Efficient Hyperthermia

    Directory of Open Access Journals (Sweden)

    Ihab M. Obaidat

    2015-01-01

    Full Text Available Localized magnetic hyperthermia using magnetic nanoparticles (MNPs under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnetic properties of MNPs. We discuss some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange anisotropy and dipolar interactions. Basic magnetic properties of MNPs such as their superparamagnetic behavior, are briefly reviewed. The influence of temperature on anisotropy and magnetization of MNPs is discussed. Recent development in self-regulated hyperthermia is briefly discussed. Some physical and practical limitations of using MNPs in magnetic hyperthermia are also briefly discussed.

  18. Anomalous magnetisation in a Fe_3Pt-FeRh film occurring at T~120 K in the field-cooled-cooling curves for low magnetic fields

    OpenAIRE

    Salem-Sugui, Jr., S.; Alvarenga, A. D.; R. D. Noce; Mejia, C. Salazar; Salim, H.; Gandra, F. G.

    2010-01-01

    We report on an anomalous magnetization observed with temperature for low magnetic fields applied in the plane of a film formed by a thin layer of Fe-Rh deposited on a thin foil of ordered Fe$_3$Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetization curve at temperatures near 120 K. We also observe an aging effect which broads the metamagnetic-like transition suggesting the existence of Fe-Rh antiferromagnetic clusters which appar...

  19. Robust Magnetic Properties of a Sublimable Single-Molecule Magnet.

    Science.gov (United States)

    Kiefl, Evan; Mannini, Matteo; Bernot, Kevin; Yi, Xiaohui; Amato, Alex; Leviant, Tom; Magnani, Agnese; Prokscha, Thomas; Suter, Andreas; Sessoli, Roberta; Salman, Zaher

    2016-06-28

    The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we present a rare example of an SMM system that can be thermally sublimated on gold surfaces while maintaining its intact chemical structure and magnetic properties. Muon spin relaxation and ac susceptibility measurements are used to demonstrate that, unlike other SMMs, the magnetic properties of this system in thin films are very similar to those in the bulk, throughout the full volume of the film, including regions near the metal and vacuum interfaces. These results exhibit the robustness of chemical and magnetic properties of this complex and provide important clues for the development of nanostructures based on SMMs. PMID:27139335

  20. Light-by-light-type corrections to the muon anomalous magnetic moment at four-loop order

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Teilchenphysik; Liu, Tao; Steinhauser, Matthias [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Teilchenphysik; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Smirnov, Alexander V. [Moscow State Univ. (Russian Federation). Scientific Research Computing Center; Smirnov, Vladimir A. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics

    2015-08-15

    The numerically dominant QED contributions to the anomalous magnetic moment of the muon stem from Feynman diagrams with internal electron loops. We consider such corrections and present a calculation of the four-loop light-by-light-type corrections where the external photon couples to a closed electron or muon loop. We perform an asymptotic expansion in the ratio of electron and muon mass and reduce the resulting integrals to master integrals which we evaluate using analytical and numerical methods. We confirm the results present in the literature which are based on different computational methods.

  1. Lattice Calculation of the Connected Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment

    CERN Document Server

    Jin, Luchang; Christ, Norman; Hayakawa, Masashi; Izubuchi, Taku; Lehner, Christoph

    2015-01-01

    The anomalous magnetic moment of muon, $g-2$, is a very precisely measured quantity. However, the current measurement disagrees with standard model by about 3 standard deviations. Hadronic vacuum polarization and hadronic light by light are the two types of processes that contribute most to the theoretical uncertainty. I will describe how lattice methods are well-suited to provide a first-principle's result for the hadronic light by light contribution, the various numerical strategies that are presently being used to evaluate it, our current results and the important remaining challenges which must be overcome.

  2. (In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium

    CERN Document Server

    Ferrer, E J; Paret, D Manreza; Martinez, A Perez; Sanchez, A

    2015-01-01

    We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.

  3. First-principles determination of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ruqian; Yang Zongxian; Hong Jisang [Department of Physics, University of California, Irvine, CA (United States)

    2003-02-12

    First-principles density functional theory calculations have achieved great success in the exciting field of low-dimension magnetism, in explaining new phenomena observed in experiments as well as in predicting novel properties and materials. As known, spin-orbit coupling (SOC) plays an extremely important role in various magnetic properties such as magnetic anisotropy, magnetostriction, magneto-optical effects and spin-dynamics. Using the full potential linearized augmented plane wave approach, we have carried out extensive investigations for the effects of SOC in various materials. Results of selected examples, such as structure and magnetic properties of Ni/Cu(001), magnetism and magnetic anisotropy in magnetic Co/Cu(001) thin films, wires and clusters, magnetostriction in FeGa alloys and magneto-optical effects in Fe/Cr superlattices, are discussed.

  4. Bound states, resonances, and symmetries of a neutral Dirac particle with anomalous magnetic moment, coupled to a fixed monopole

    International Nuclear Information System (INIS)

    For the system consisting of a neutral Dirac particle with anomalous magnetic moment, interacting with a fixed magnetic monopole, zero-energy bound states are constructed for each possible value of the total angular momentum. Results of Kazama and Yang for the charge--monopole system are used to deduce the existence of other bound states for this system, when the mass of the bound particle is nonzero. In the zero-mass case, there are no other bound states, but there are resonant states, and these are determined exactly. A noncompact, so(3,2) symmetry algebra of the zero-energy bound states is given for the finite-mass case and for the zero-mass case. In each case the infinite number of such states is associated with an irreducible Majorana representation of the algebra

  5. Anomalous dimension, chiral phase transition and inverse magnetic catalysis in soft-wall AdS/QCD

    Science.gov (United States)

    Fang, Zhen

    2016-07-01

    A modified soft-wall AdS/QCD model with a z-dependent bulk scalar mass is proposed. We argue for the necessity of a modified bulk scalar mass from the quark mass anomalous dimension and carefully constrain the form of bulk mass by the corresponding UV and IR asymptotics. After fixing the form of bulk scalar mass, we calculate the mass spectra of (axial-)vector and pseudoscalar mesons, which have a good agreement with the experimental data. The behavior of chiral phase transition is also investigated, and the results are consistent with the standard scenario and lattice simulations. Finally, the issue of chiral magnetic effects is addressed. We find that the inverse magnetic catalysis emerges naturally from the modified soft-wall model, which is consistent with the recent lattice simulations.

  6. Anomalous Hall Effect in a Kagome Ferromagnet

    Science.gov (United States)

    Ye, Linda; Wicker, Christina; Suzuki, Takehito; Checkelsky, Joseph; Joseph Checkelsky Team

    The ferromagnetic kagome lattice is theoretically known to possess topological band structures. We have synthesized large single crystals of a kagome ferromagnet Fe3Sn2 which orders ferromagnetically well above room temperature. We have studied the electrical and magnetic properties of these crystals over a broad temperature and magnetic field range. Both the scaling relation of anomalous Hall effect and anisotropic magnetic susceptibility show that the ferromagnetism of Fe3Sn2 is unconventional. We discuss these results in the context of magnetism in kagome systems and relevance to the predicted topological properties in this class of compounds. This research is supported by DMR-1231319.

  7. Quantum anomalous Hall effect and a nontrivial spin-texture in ultra-thin films of magnetic topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Duong, Le Quy; Das, Tanmoy; Feng, Y. P.; Lin, Hsin, E-mail: nilnish@gmail.com [Graphene Research Centre and Department of Physics, National University of Singapore, Singapore 117546 (Singapore)

    2015-05-07

    We study the evolution of quantum anomalous Hall (QAH) effect for a Z{sub 2} topological insulator (TI) thin films in a proximity induced magnetic phase by a realistic layered k·p model with interlayer coupling. We examine three different magnetic configurations in which ferromagnetic (FM) layer(s) is added either from one side (FM-TI), from both sides (FM-TI-FM), or homogeneously distributed (magnetically doped) in a TI slab. We map out the thickness-dependent topological phase diagram under various experimental conditions. The critical magnetic exchange energy for the emergence of QAH effect in the latter two cases decreases monotonically with increasing number of quintuple layers (QLs), while it becomes surprisingly independent of the film thickness in the former case. The gap size of the emergent QAH insulator depends on the non-magnetic “parent” gap of the TI thin film and is tuned by the FM exchange energy, opening a versatile possibility to achieve room-temperature QAH insulator in various topological nanomaterials. Finally, we find that the emergent spin-texture in the QAH effect is very unconventional, non-“hedgehog” type; and it exhibits a chiral out-of-plane spin-flip texture within the same valence band which is reminiscent of dynamical “skyrmion” pattern, except our results are in the momentum space.

  8. Anomalous Optical and Electronic Properties of CaTiO3 Perovskites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the help of the first-principles full potential linearized augmented plane wave method, absorption coefficients, reflectivity, dielectric behavior and electronic properties, including electronic energy bands, density of states and charge density distributions, are studied for the tetragonal and cubic CaTiO3. By considering the thermal expansion effects, an approximate method is proposed for the study of the stability of ground state and a tendency of phase transition, based on the minimum free energy principle. Subsequently, numerical calculations are carried out by using the first-principles perturbation method. We demonstrate that the high-temperature phase is cubic. It is shown that optical spectra in tetragonal phase exhibit single-peak feature and differ from multi-peak character in cubic. We find that strong orbital hybridization results in the co-valent bonds between Ti 3d and O 2p electrons and forms two-type dipoles (Ti-O1 and Ti-O2) in tetragonal, while the Ti-O dipoles are identical in cubic. It is argued that crystal structure determines the dipole distributions and leads to some electron states among which the dipole-dipole transition forbidden is a key, causing such anomalous optical phenomena with the insulator characteristics. The predicted charge density distribution and the tendency of phase transition from tetragonal to cubic are in good agreement with experimental observations.

  9. Quantum-chemical approach to cohesive properties of metals: Anomalous behaviour of Be

    International Nuclear Information System (INIS)

    Calculations based upon the incremental scheme, i.e. an expansion of the total correlation energy in terms of one-body, two-body and higher-order contributions, have been performed on a variety of solids with band gaps. Metals require a special treatment. Via an embedding scheme, we can force localization in metallic-like model systems and can mimic the metallic band structure within finite fragments of the solid. This allows for a gradual delocalization towards the infinite crystal within the incremental scheme. Up to now we successfully applied the method to magnesium and group 12 elements where in all cases the ground-state properties agree very well with experiment.The beryllium crystal has the same hcp structure as Mg; the atoms are characterized by closed ns2 shells. At the same time Mg is almost free-electron-like whereas Be, although in general metallic, shows a lower density of states of almost entirely p character at the Fermi energy; that is the reason for the anomalous behavior of Be compared with other group 2 and 12 metals

  10. Aging and memory phenomena in magnetic and transport properties of vortex matter: a brief review

    OpenAIRE

    Nicodemi, Mario; Jensen, Henrik Jeldtoft

    2001-01-01

    There is mounting experimental evidence that strong off-equilibrium phenomena, such as ``memory'' or ``aging'' effects, play a crucial role in the physics of vortices in type II superconductors. We give a short review, based on a recently introduced schematic vortex model, of current progresses in understanding out of equilibrium vortex behaviours. We develop a unified description of ``memory'' phenomena in magnetic and transport properties, such as magnetisation loops and their ``anomalous''...

  11. Magnetically Responsive Nanostructures with Tunable Optical Properties.

    Science.gov (United States)

    Wang, Mingsheng; Yin, Yadong

    2016-05-25

    Stimuli-responsive materials can sense specific environmental changes and adjust their physical properties in a predictable manner, making them highly desired components for designing novel sensors, intelligent systems, and adaptive structures. Magnetically responsive structures have unique advantages in applications, as external magnetic stimuli can be applied in a contactless manner and cause rapid and reversible responses. In this Perspective, we discuss our recent progress in the design and fabrication of nanostructured materials with various optical responses to externally applied magnetic fields. We demonstrate tuning of the optical properties by taking advantage of the magnetic fields' abilities to induce magnetic dipole-dipole interactions or control the orientation of the colloidal magnetic nanostructures. The design strategies are expected to be extendable to the fabrication of novel responsive materials with new optical effects and many other physical properties. PMID:27115174

  12. Magnetic Properties of NdAl2

    DEFF Research Database (Denmark)

    Bak, P.

    1974-01-01

    The magnetic properties of NdAl2 are calculated using a Hamiltonian including crystal-field and isotropic exchange interaction terms. A two-dimensional mean-field theory is evaluated to calculate single-crystal magnetization curves. It is shown that the magnetic properties can be understood using...... the crystal-field parameters derived from the magnetic exciton spectrum measured by Houmann et al. by means of inelastic neutron scattering. The combined lambda -Schottky anomaly in the heat capacity is explained. No additional parameters are introduced....

  13. MAGNETIC NANOFLUID WITH ANTITUMORAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Alexandru Mihai Grumezescu

    2012-09-01

    Full Text Available The present study deals with the synthesis and characterization of magnetic nanofluid and it’s in vitro anti-cancer activity against HEp2 cells. The magnetic nanofluid with an average size of 10 nm was synthesized via a modified precipitation technique and characterized by FT-IR, XRD, DTA-TG and TEM. After 24 h incubation of HEp2 with the magnetic nanofluid, significant changes in the cell morphology were discernible in fluorescent microscopy. Cytotoxicity assay shows that the magnetic nanofluid exhibits significant cytotoxicity against HEp2, 50% of thee cells being killed after 24 hours incubation with magnetic nanofluid without any external alternating magnetic field.

  14. Properties of Simulated Magnetized Galaxy Clusters

    CERN Document Server

    Dolag, K

    2000-01-01

    We study the evolution of magnetized clusters in a cosmological environment using magneto-hydro dynamical simulations. Large scale flows and merging of subclumps generate shear flows leading to Kelvin-Helmholtz instabilities, which, in addition to the compression of the gas where the magnetic field is frozen in, further amplify the magnetic field during the evolution of the cluster. Therefore, well-motivated initial magnetic fields of $^{1/2}=10^{-9} {\\rm G}$ reach the observed $\\sim\\mu{\\rm G}$ field strengths in the cluster cores at $z=0$. These magnetized clusters can be used to study the final magnetic field structure, the dynamical importance of magnetic fields for the interpretation of observed X-Ray properties, and help to constrain further processes in galaxy clusters like the population of relativistic particles giving rise to the observed radio halos or the behavior of magnetized cooling flows.

  15. The Characterization of the Magnetic Properties of Soft Magnetic Materials

    DEFF Research Database (Denmark)

    Larsen, Raino Michael

    1996-01-01

    The hysteresis curve and magnetic properties such as permeability, saturation induction, residual induction, coercive force and hysteresis losses are presented. The design and construction of equipment making it possible to measure true DC-values as well as AC-properties of toroid rings...

  16. Connected and leading disconnected hadronic light-by-light contribution to the muon anomalous magnetic moment with physical pion mass

    CERN Document Server

    Blum, Thomas; Hayakawa, Masashi; Izubuchi, Taku; Jin, Luchang; Jung, Chulwoo; Lehner, Christoph

    2016-01-01

    We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams. We incorporate algorithmic improvements developed in our previous work. The calculation was performed on the $48^3 \\times 96$ ensemble generated with a physical-pion-mass and a 5.5 fm spatial extent by the RBC and UKQCD collaborations using the chiral, domain wall fermion (DWF) formulation. We find $a_\\mu^{\\text{HLbL}} = 5.35 (1.35) \\times 10^{- 10}$, where the error is statistical only. The finite-volume and finite lattice-spacing errors could be quite large and are the subject of on-going research. The omitted disconnected graphs, while expected to give a correction of order 10\\%, also need to be computed.

  17. Can the two-Higgs-doublet model survive the constraint from the muon anomalous magnetic moment, as suggested?

    International Nuclear Information System (INIS)

    Requiring the two-Higgs-doublet model II to accommodate the 3σ deviation in the muon anomalous magnetic moment imposes specific constraints on the Higgs spectrum. We analyze the combination of all the relevant available constraints on the model parameter space. The use of constraints from b→sγ, the precision electroweak measurements of Rb, and the ρ parameter, together with exclusions from direct searches at CERN LEP, gives extremely severe restrictions on the model parameters. That is 'almost enough' to destroy the model altogether. The exclusion would be even stronger if the direct searches could be optimized to complement the other constraints, as will be discussed in detail in this work

  18. Scattering of a Spin-Polarized Neutral Fermion with the Anomalous Magnetic Moment in AN Aharonov-Casher Configuration

    Science.gov (United States)

    Khalilov, V. R.

    The scattering of a nonrelativistic neutral massive fermion having the anomalous magnetic moment (AMM) in an electric field of a uniformly charged long conducting thread aligned perpendicularly to the fermion motion is considered to study the so-called Aharonov-Casher (AC) effect by taking into account the particle spin. For this solution, the nonrelativistic Dirac-Pauli equation for a neutral massive fermion with AMM in (3+1) dimensions is found, which takes into account explicitly the particle spin and interaction between AMM of moving fermion and the electric field. Expressions for the scattering amplitude and the cross-section are obtained for spin-polarized massive neutral fermion scattered off the above conducting thread. We conclude that the scattering amplitude and cross-section of spin-polarized massive neutral fermions are influenced by the interaction of AMM of moving neutral fermions with the electric field as well as by the polarization of fermion beam in the initial state.

  19. Electron's anomalous magnetic moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field

    CERN Document Server

    Elhandi, S; attaourti, Y; Manaut, B; Oufni, L

    2010-01-01

    The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to new results, namely the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the non relativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.

  20. Anomalous behavior of magnetostriction and magnetic ac-suseptibility of Gd1-xPrxCo5 polycrystals

    Directory of Open Access Journals (Sweden)

    A. Amirabadizadeh

    2003-12-01

    Full Text Available Magnetostriction and low field ac-susceptibility of polycrystalline Gd1-xPrxCo5 (x = 0, 0.1 and 0.5 alloys are measured in temperature region of 77-300 K. XRD patterns show that our samples are single phase. For x = 0 (GdCo5 there are no anomaly in temperature dependence of magnetostriction and ac-susceptibility curves. For x = 0.1 and 0.5 temperature dependence of ac-susceptibilities show easy-axes phase transitions. In the case of x = 0.1 sample, the easy-axes of magnetization changes from canted to axial (practically, hexagonal c-axis direction as temperature increases, and ac-susceptibility of x = 0.5 sample shows two iterative transitions, first from basal to canted then canted to axial. Magnetostriction of Pr contained samples anomalously decreases at spin reorientation regions.

  1. Hadron production in e+e- annihilation at BaBar, and implication for the muon anomalous magnetic moment

    CERN Document Server

    Porter, Frank C

    2013-01-01

    The BaBar collaboration has an extensive program of studying hadronic cross sections in low-energy e+e- collisions, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for illuminating the current ~3.6 sigma difference between the predicted and the experimental values. We have published results on a number of processes with two to six hadrons in the final state. We report here the results of recent studies with final states that constitute the main contribution to the hadronic cross section in the energy region between 1 and 3 GeV, as e+e- to K+K-, pi+pi-, and e+e- to 4 hadrons.

  2. Magnetic and Electrical Properties of Leachate

    Directory of Open Access Journals (Sweden)

    Kartika Kirana

    2011-11-01

    Full Text Available Heavy metals content as well as magnetic and electrical properties of leachate from Sarimukti, West Java were studied in an attempt to seek correlation between heavy metals content and magnetic/electrical properties. Such correlation is expected to open the way for the use of magnetic/electrical properties as proxy indicators for the concentration of heavy metals in the leachate. The number of leachate samples studied is 21; 15 were taken spatially at depth of 1 m while the remaining 6 samples were taken vertically at a particular point. Measurement results showed that the heavy metals content in the leachate has a smaller concentration, except for Fe. The correlation between magnetic susceptibility and heavy metals content was found to be not so significant. The best correlation coefficient between magnetic susceptibility with heavy metals in leachate was found in Zn. Correlation between electrical conductivity and heavy metal is also not so significant, except for Zn and Cd. The use of magnetic properties as proxy indicator for heavy metals content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Correlation between magnetic susceptibility, electrical conductivity and heavy metal content would be good if each quantity has a large value.

  3. Depolarization of high-energy neutral particles in crystals and the possibility to measure anomalous magnetic moments of short-lived hyperons

    CERN Document Server

    Baryshevsky, V G

    2016-01-01

    The degree of depolarization of neutral particles in crystals can reach tens of percents over the crystal length of several centimeters, which can be the basis for possible experimental application of the depolarization effect for measuring anomalous magnetic moments of short-lived neutral hyperons.

  4. f-f Magnetic polaron Wigner glass and anomalous superconductivity in U sub 1 sub - sub x Th sub x Be sub 1 sub 3

    CERN Document Server

    Kasuya, T

    2000-01-01

    Mechanisms of the anomalous properties in the heavy fermion superconductor UBe sub 1 sub 3 and its alloys, in particular for the Th dopings, are studied in detail based on the fundamental electronic states to be consistent with all the crucial experimental results. As the reference systems for the magnetic polaron formation, Ce monopnictides, as well as USb and UTe, are mentioned. From detailed systematic studies of the dilute alloy systems, it is postulated that the 5f states in UBe sub 1 sub 3 split into the well-localized core 5f GAMMA sup 2 sub 7 singlet state and other delocalized 5f states situated around the Fermi energy forming the f-f magnetic polarons through the strong intra-atomic ferromagnetic f-f exchange interaction. The accompanied lattice polarons are also shown to play important roles. In the p-d band states, the f-f exchange interaction and the intersite p-f mixing interactions for the p-f Kondo state are of nearly equal strengths causing a rich variety of delicately balanced states. For th...

  5. Anomalous-plasmoid-ejection-induced secondary magnetic reconnection: modeling solar flares and coronal mass ejections by laser–plasma experiments

    Institute of Scientific and Technical Information of China (English)

    Quanli; Dong; Dawei; Yuan; Shoujun; Wang; Xun; Liu; Yutong; Li; Xiaoxuan; Lin; Huigang; Wei; Jiayong; Zhong; Shaoen; Jiang; Yongkun; Ding; Bobin; Jiang; Kai; Du; Yongjian; Tang; Mingyang; Yu; Xiantu; He; Neng; Hua; Zhanfeng; Qiao; Kuixi; Huang; Ming; Chen; Jianqiang; Zhu; Gang; Zhao; Zhengming; Sheng; Jie; Zhang

    2013-01-01

    The driving mechanism of solar flares and coronal mass ejections is a topic of ongoing debate, apart from the consensus that magnetic reconnection plays a key role during the impulsive process. While present solar research mostly depends on observations and theoretical models, laboratory experiments based on high-energy density facilities provide the third method for quantitatively comparing astrophysical observations and models with data achieved in experimental settings.In this article, we show laboratory modeling of solar flares and coronal mass ejections by constructing the magnetic reconnection system with two mutually approaching laser-produced plasmas circumfused of self-generated megagauss magnetic fields. Due to the Euler similarity between the laboratory and solar plasma systems, the present experiments demonstrate the morphological reproduction of flares and coronal mass ejections in solar observations in a scaled sense,and confirm the theory and model predictions about the current-sheet-born anomalous plasmoid as the initial stage of coronal mass ejections, and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary current sheet conjoined with two bright ridges identified as solar flares.

  6. Anomalous Increase in Nematic-Isotropic Transition Temperature in Dimer Molecules Induced by a Magnetic Field

    Science.gov (United States)

    Salili, S. M.; Tamba, M. G.; Sprunt, S. N.; Welch, C.; Mehl, G. H.; Jákli, A.; Gleeson, J. T.

    2016-05-01

    We have determined the nematic-isotropic transition temperature as a function of an applied magnetic field in three different thermotropic liquid crystalline dimers. These molecules are comprised of two rigid calamitic moieties joined end to end by flexible spacers with odd numbers of methylene groups. They show an unprecedented magnetic field enhancement of nematic order in that the transition temperature is increased by up to 15 K when subjected to a 22 T magnetic field. The increase is conjectured to be caused by a magnetic-field-induced decrease of the average bend angle in the aliphatic spacers connecting the rigid mesogenic units of the dimers.

  7. Suppressing the neoclassical tearing modes in tokamaks during anomalous transverse transport owing to predomination of the magnetic well effect over the bootstrap drive

    International Nuclear Information System (INIS)

    Suppression of neoclassical tearing modes in tokamaks under anomalous transverse transport conditions when the magnetic well effect predominates over the bootstrap drive is studied. Reduced equations of transfer are used in the description. Geodetic effects are considered during the magnetic well calculation. A criterion for the stabilization of neoclassical tearing modes by the compound effect at an arbitrary level of the transverse heat transport by electrons and ions is derived

  8. Anomalous thickness-dependent strain states and strain-tunable magnetization in Zn-doped ferrite epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y. J.; Bao, J.; Gao, C., E-mail: zlluo@ustc.edu.cn, E-mail: cgao@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yang, M. M.; Luo, Z. L., E-mail: zlluo@ustc.edu.cn, E-mail: cgao@ustc.edu.cn; Hu, C. S.; Chen, X. C.; Pan, G. Q. [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026 (China); Huang, H. L. [CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, S.; Wang, J. W.; Li, P. S.; Liu, Y.; Zhao, Y. G. [Department of Physics and State Key Laboratory of New Ceramics, Fine Processing, Tsinghua University, Beijing 100084 (China); Jiang, T.; Liu, Y. K.; Li, X. G. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science, Technology of China, Hefei, Anhui 230026 (China)

    2014-05-07

    A series of Zn{sub x}Fe{sub 3−x}O{sub 4} (ZFO, x = 0.4) thin films were epitaxially deposited on single-crystal (001)-SrTiO{sub 3} (STO) substrates by radio frequency magnetron sputtering. The anomalous thickness-dependent strain states of ZFO films were found, i.e., a tensile in-plane strain exists in the thinner ZFO film and which monotonously turns into compressive in the thicker films. Considering the lattice constant of bulk ZFO is bigger than that of STO, this strain state cannot be explained in the conventional framework of lattice-mismatch-induced strain in the hetero-epitaxial system. This unusual phenomenon is proposed to be closely related to the Volmer-Weber film growth mode in the thinner films and incorporation of the interstitial atoms into the island's boundaries during subsequent epitaxial growth of the thicker films. The ZFO/STO epitaxial film is found in the nature of magnetic semiconductor by transport measurements. The in-plane magnetization of the ZFO/STO films is found to increase as the in-plane compressive strain develops, which is further proved in the (001)-ZFO/PMN-PT film where the film strain state can be in situ controlled with applied electric field. This compressive-strain-enhanced magnetization can be attributed to the strain-mediated electric-field-induced in-plane magnetic anisotropy field enhancement. The above results indicate that strain engineering on magnetic oxide semiconductor ZFO films is promising for novel oxide-electronic devices.

  9. Anomalous thickness-dependent strain states and strain-tunable magnetization in Zn-doped ferrite epitaxial films

    Science.gov (United States)

    Yang, Y. J.; Yang, M. M.; Luo, Z. L.; Hu, C. S.; Bao, J.; Huang, H. L.; Zhang, S.; Wang, J. W.; Li, P. S.; Liu, Y.; Zhao, Y. G.; Chen, X. C.; Pan, G. Q.; Jiang, T.; Liu, Y. K.; Li, X. G.; Gao, C.

    2014-05-01

    A series of ZnxFe3-xO4 (ZFO, x = 0.4) thin films were epitaxially deposited on single-crystal (001)-SrTiO3 (STO) substrates by radio frequency magnetron sputtering. The anomalous thickness-dependent strain states of ZFO films were found, i.e., a tensile in-plane strain exists in the thinner ZFO film and which monotonously turns into compressive in the thicker films. Considering the lattice constant of bulk ZFO is bigger than that of STO, this strain state cannot be explained in the conventional framework of lattice-mismatch-induced strain in the hetero-epitaxial system. This unusual phenomenon is proposed to be closely related to the Volmer-Weber film growth mode in the thinner films and incorporation of the interstitial atoms into the island's boundaries during subsequent epitaxial growth of the thicker films. The ZFO/STO epitaxial film is found in the nature of magnetic semiconductor by transport measurements. The in-plane magnetization of the ZFO/STO films is found to increase as the in-plane compressive strain develops, which is further proved in the (001)-ZFO/PMN-PT film where the film strain state can be in situ controlled with applied electric field. This compressive-strain-enhanced magnetization can be attributed to the strain-mediated electric-field-induced in-plane magnetic anisotropy field enhancement. The above results indicate that strain engineering on magnetic oxide semiconductor ZFO films is promising for novel oxide-electronic devices.

  10. Dynamical properties of unconventional magnetic systems

    Energy Technology Data Exchange (ETDEWEB)

    Helgesen, G. [ed.

    1997-05-01

    The Advanced Study Institute addressed the current experimental and theoretical knowledge of the dynamical properties of unconventional magnetic systems including low-dimensional and mesoscopic magnetism, unconventional ground state, quantum magnets and soft matter. The main approach in this Advanced Study Institute was to obtain basic understanding of co-operative phenomena, fluctuations and excitations in the wide range unconventional magnetic systems now being fabricated or envisioned. The report contains abstracts for lectures, invited seminars and posters, together with a list of the 95 participants from 24 countries with e-mail addresses

  11. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    Science.gov (United States)

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-12-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature.

  12. Magnetic trapping of silver and copper, and anomalous spin relaxation in the ag-he system.

    Science.gov (United States)

    Brahms, Nathan; Newman, Bonna; Johnson, Cort; Greytak, Tom; Kleppner, Daniel; Doyle, John

    2008-09-01

    We have trapped large numbers of copper (Cu) and silver (Ag) atoms using buffer-gas cooling. Up to 3 x 10{12} Cu atoms and 4 x 10{13} Ag atoms are trapped. Lifetimes are as long as 5 s, limited by collisions with the buffer gas. Ratios of elastic to inelastic collision rates with He are >or=10{6}, suggesting Cu and Ag are favorable for use in ultracold applications. The temperature dependence of the Ag-3He collision rate varies as T;{5.8+/-0.4}. We find that this temperature dependence is inconsistent with the behavior predicted for relaxation arising from the spin-rotation interaction, and conclude that the Ag-3He system displays anomalous collisional behavior in the multiple-partial wave regime. Gold (Au) was ablated into 3He buffer gas, however, atomic Au lifetimes were observed to be too short to permit trapping.

  13. Structure and magnetic properties of powder soft magnetic materials

    Directory of Open Access Journals (Sweden)

    J. Konieczny

    2007-01-01

    Full Text Available Purpose: The paper presents influence of high-energy mechanical milling process, isothermal annealing and toa combination of these two technologies of cobalt base metallic glasses Co77Si11.5B11.5 on magnetic propertiesand their structure.Design/methodology/approach: The powder test piece obtained from the input amorphous ribbon in highenergyball milling. The diffraction examinations and examinations of thin foils were made on the JEOL JEM200CX transmission electron microscope. Observations of the structure of powders were made on the OptonDSM-940 scanning electron microscope. The X-ray tests were realized with the use of the XRD 7 SEIFERTFPMdiffractometer.Findings: analysis of the magnetic properties test results of the of the Co77Si11.5B11.5 powders obtained inthe high-energy ball of milling process proved that the process causes significant decrease in the magneticproperties. The structure and magnetic properties of this material may be improved by means of a proper choiceof parameters of this process as well as the final thermal treatment.Research limitations/implications: For the powders, further magnetical, structure and composition examinationsare planed.Practical implications: The amorphous and nanocrystalline metal powders obtained by high-energy ballmilling of metallic glasses feature an alternative to solid alloys and make it possible to obtain the ferromagneticnanocomposites, whose shape and dimensions can be freely formed.Originality/value: The paper presents influence of parameters of the high-energy ball milling process onstructure and magnetic properties of soft magnetic powder materials obtained in this technique. Results and adiscussion of the influence of high energy mechanical milling process on particle size and their distribution aswell as structure and magnetic properties of investigated samples is presented.

  14. On magnetic monopoles, the anomalous g-factor of the electron and the spin-orbit coupling in the Dirac theory

    CERN Document Server

    Coddens, Gerrit

    2016-01-01

    We discuss the algebra and the interpretation of the anomalous Zeeman effect and the spin-orbit coupling within the Dirac theory. Whereas the algebra for the anomalous Zeeman effect is impeccable and therefore in excellent agreement with experiment, the physical interpretation of that algebra uses images that are based on macroscopic intuition but do not correspond to the meaning of this algebra. The interpretation violates the Lorentz symmetry. We give an alternative intuitive description of the meaning of this effect, which respects the symmetry and is exact. It can be summarized by stating that a magnetic field makes any charged particle spin. We show also that the traditional discussion about magnetic monopoles confuses two issues, viz. the symmetry of the Maxwell equations and the quantization of charge. These two issues define each a different concept of magnetic monopole. They cannot be merged together into a unique all-encompassing issue. We also generalize the minimal substitution for a charged parti...

  15. Spontaneous anomalous and spin Hall effects due to spin-orbit scattering of evanescent wave functions in magnetic tunnel junctions.

    Science.gov (United States)

    Vedyayev, A; Ryzhanova, N; Strelkov, N; Dieny, B

    2013-06-14

    We theoretically investigated the anomalous Hall effect (AHE) and spin Hall effect (SHE) transversal to the insulating spacer I, in magnetic tunnel junctions of the form F/I/F where the F's are ferromagnetic layers and I represents a tunnel barrier. We considered the case of purely ballistic (quantum mechanical) transport. These effects arise because of the asymmetric scattering of evanescent wave functions due to the spin-orbit interaction in the tunnel barrier. The AHE and SHE we investigated have a surface nature due to the proximity effect. Their amplitude is of first order in the scattering potential. This contrasts with ferromagnetic metals wherein these effects are of second (side-jump scattering) and third (skew scattering) order in these potentials. The value of the AHE current in the insulating spacer may be much larger than that in metallic ferromagnetic electrodes. For the antiparallel orientation of the magnetizations in the two F electrodes, a spontaneous Hall current exists even at zero applied voltage. PMID:25165958

  16. Anomalous origin of the left circumflex coronary artery from the pulmonary artery. A very rare congenital anomaly in an adult patient diagnosed by cardiovascular magnetic resonance

    Directory of Open Access Journals (Sweden)

    Giannitsis Evangelos

    2008-01-01

    Full Text Available Abstract Here we report for the first time on the diagnostic potential of cardiovascular magnetic resonance (CMR to delineate the proximal course of an anomalous left circumflex coronary artery (LCX originating from the right pulmonary artery in an adult patient with no other form of congenital heart disease. The patient was referred to our institution due to exertional chest discomfort. X-Ray coronary angiography showed a normal left anterior descending coronary artery (LAD and right coronary artery (RCA, while the LCX was filled retrograde by collateral flow through the LAD and the RCA. The origin of the LCX was postulated to be the pulmonary artery, but the exact origin of the anomalous artery could not be depicted on conventional angiograms. CMR provided the unambiguous depiction of the origin of the anomalous LCX from the right pulmonary artery and the delineation of its proximal course in this case of a very rare coronary anomaly in adults.

  17. Magnetic properties of sheet silicates

    International Nuclear Information System (INIS)

    Susceptibility, magnetisation and Moessbauer measurements are reported for a representative selection of 2:1 layer phyllosilicates. Eight samples from the mica, vermiculite and smectite groups include examples diluted in iron which are paramagnetic at all temperatures, as well as iron-rich silicates which order magnetically below 10 K. Anisotropic susceptibility of crystals of muscovite, biotite and vermiculite is quantitatively explained with a model where the Fe2+ ions lie in sites of effective trigonal symmetry, the trigonal axis lying normal to the sheets. The ferrous ground state is an orbital singlet. Ferric iron gives an isotropic contribution to the susceptibility. Fe2+-Fe2+ exchange interactions are ferromagnetic with Gapprox. equal to2 K, whereas Fe3+-Fe3+ coupling is antiferromagnetic in the purely ferric minerals. A positive paramagnetic Curie temperature for glauconite may be attributable to Fe2+ → Fe3+ charge transfer. Magnetic order was found to set in inhomogeneously for glauconite at 1-7 K. One biotite sample showed an antiferromagnetic transition at Tsub(N) = 7 K marked by a well-defined susceptibility maximum. Its magnetic structure, consisting of ferromagnetic sheets with moments in their planes coupled antiferromagnetically by other, weak interactions, resembles that found earlier for the 1:1 mineral greenalite. (orig.)

  18. Anomalous magnetic moments in Fe-Pt and Fe-Pd Invar alloys under high pressure

    CERN Document Server

    Matsushita, M; Endo, S; Ishizuka, M; Kindo, K; Ono, F

    2002-01-01

    Magnetization measurements have been carried out for disordered Fe sub 7 sub 2 Pt sub 2 sub 8 , Fe sub 6 sub 6 Pd sub 3 sub 4 , and Fe sub 6 sub 8 Pd sub 3 sub 2 Invar alloys under high pressure using a technique combining a pressure-clamp-type Drickamer cell and a pulse magnet. In Fe sub 7 sub 2 Pt sub 2 sub 8 at room temperature, the magnetization decreased rapidly with increasing pressure up to 2.5 GPa, but above 2.5 GPa the rate of decrease became small and remained at a small value up to 5.6 GPa. In Fe-Pd Invar alloys at room temperature, the magnetization decreased linearly with increasing pressure. But, at 4.2 K, the change of magnetization with pressure was small in Fe sub 6 sub 6 Pd sub 3 sub 4 , which means that Fe sub 6 sub 6 Pd sub 3 sub 4 behaves as a strong ferromagnet.

  19. Properties of magnetic nano-particles

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1997-01-01

    The intrinsic thermodynamic magnetic properties of clusters are discussed using spin wave theory for a Heisenberg model, with a fixed magnitude of the spins S-i = S and site independent nearest neighbor exchange interaction. The consequences of the more realistic Hubbard model is considered...... in which we allow for a magnetization profile at T = 0 and a structural relaxation, which in turn will give rise to a site dependent exchange interaction. Et is concluded that correlation effects among the electrons play a very important role in small clusters, albeit not modifying the thermodynamic...... properties drastically. The finite cluster size gives foremost rise to a discrete excitation spectrum with a large energy gap to the ground state. The relaxation of the magnetization during the reversal of the external magnetic field is discussed. A first step towards a quantitative understanding...

  20. Anomalous magnetism of superconducting Mg-doped InN film

    Directory of Open Access Journals (Sweden)

    P. H. Chang

    2016-02-01

    Full Text Available We report on the Meissner effect of Mg-doped InN film with superconducting transition onset temperature Tc,onset of 5 K. Mg-doped InN is magnetically ordered and exhibits a simultaneous first-order magnetic and electric transition near 50 K. Its behavior is similar to that of iron-based superconductors. A strong correlation is proposed to exist between structural distortion and superconductivity when Mg is doped into InN. The suppression of magnetic ordering close to Tc by doping is further demonstrated by anisotropic magnetoresistance and M-H measurements. The findings suggest that the superconducting mechanism in the system may not be conventional BCS.

  1. Magnetism of uranium/iron multilayers: II. Magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Beesley, A M [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Zochowski, S W [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Thomas, M F [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Herring, A D F [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Langridge, S [ISIS, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Brown, S D [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Ward, R C C [Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Wells, M R [Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Springell, R [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Stirling, W G [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lander, G H [European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, Karlsruhe, D-76125 (Germany)

    2004-12-01

    Well-defined U/Fe multilayers of varying layer thicknesses and bilayer repeat numbers were prepared by a dc magnetron sputtering method. Polarized neutron reflectometry, off-specular neutron diffraction and magnetic moment measurements were used to determine the physical properties of the multilayers leading to an evaluation of the magnetic moments associated with the U and Fe atoms. The multilayers exhibit ferromagnetic behaviour with the easy axis in the plane of the multilayer. The saturation magnetization was found to increase with increasing Fe-layer thickness and the magnetic moment averaged over the structured iron layers was below the bulk value of 2.2 {mu}{sub B}/Fe atom. No anomalies were observed in the magnetization from 4.2 to 375 K in temperature-dependent scans at 0.005 and 0.1 T or in magnetic field scans from 0 to 7 T at 4.2 and 295 K. The hysteresis curves exhibited a small degree of perpendicular magnetic anisotropy. The Curie temperatures for the multilayers were determined from ac susceptibility measurements and were found to be less than the bulk Fe value of 1043 K.

  2. Chiral magnetic effect and anomalous transport from real-time lattice simulations

    CERN Document Server

    Mueller, Niklas; Sharma, Sayantan

    2016-01-01

    We present a first-principle study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian $SU(N_c)$ and Abelian $U(1)$ gauge fields. Investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the Chiral magnetic (CME) and Chiral separation effect (CSE) lead to the formation of a propagating wave. We further analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on the amount of explicit chiral symmetry breaking due to finite quark mass.

  3. Magnetic properties of confined electron gas

    International Nuclear Information System (INIS)

    The effects of confinement by a two or three-dimensional harmonic potential on the magnetic properties of a free electron gas are investigated using the grand-canonical ensemble framework. At high temperatures an extension of Darwin's, Felderhof and Raval's works is made taking into account spin effects at low temperature. A comprehensive description of the magnetic properties of a free electron gas is given. The system is regarded as finite, but the boundary condition psi=0 is not introduced. The limits of weak and strong confinement are also analysed

  4. Electronic structure and magnetic properties of actinides

    International Nuclear Information System (INIS)

    The study of the actinide series shows the change between transition metal behavior and lanthanide behavior, between constant weak paramagnetism for thorium and strong Curie-Weiss paramagnetism for curium. Curium is shown to be the first metal of the actinide series to be magnetically ordered, its Neel temperature being 52K. The magnetic properties of the actinides depending on all the peripheral electrons, their electronic structure was studied and an attempt was made to determine it by means of a phenomenological model. Attempts were also made to interrelate the different physical properties which depend on the outer electronic structure

  5. Temperature dependence of the perpendicular magnetic anisotropy in Ta/Co2FeAl/MgO structures probed by Anomalous Hall Effect

    Science.gov (United States)

    Gabor, M. S.; Petrisor, T.; Pop, O.; Colis, S.; Tiusan, C.

    2015-10-01

    We report a detailed study of the temperature dependence of the magnetic anisotropy in Ta/Co2FeAl/MgO structures by means of Anomalous Hall Effect measurements. The volume magnetic anisotropy, although negligible at room temperature, shows a non-negligible value at low temperatures and favors an in-plane easy magnetization axis. The surface magnetic anisotropy, which promotes the perpendicular magnetic easy axis, shows an increase from 0.76 ± 0.05 erg /cm2 at 300 K, up to 1.08 ± 0.04 erg /cm2 at 5 K, attributed to the evolution of the Co2FeAl layer saturation magnetization with temperature.

  6. Linear and nonlinear magnetic properties of ferrofluids

    Science.gov (United States)

    Szalai, I.; Nagy, S.; Dietrich, S.

    2015-10-01

    Within a high-magnetic-field approximation, employing Ruelle's algebraic perturbation theory, a field-dependent free-energy expression is proposed which allows one to determine the magnetic properties of ferrofluids modeled as dipolar hard-sphere systems. We compare the ensuing magnetization curves, following from this free energy, with those obtained by Ivanov and Kuznetsova [Phys. Rev. E 64, 041405 (2001), 10.1103/PhysRevE.64.041405] as well as with new corresponding Monte Carlo simulation data. Based on the power-series expansion of the magnetization, a closed expression for the magnetization is also proposed, which is a high-density extension of the corresponding equation of Ivanov and Kuznetsova. From both magnetization equations the zero-field susceptibility expression due to Tani et al. [Mol. Phys. 48, 863 (1983), 10.1080/00268978300100621] can be obtained, which is in good agreement with our MC simulation results. From the closed expression for the magnetization the second-order nonlinear magnetic susceptibility is also derived, which shows fair agreement with the corresponding MC simulation data.

  7. Anomalous magnetoresistance in NiMnGa thin films

    Science.gov (United States)

    Golub, Vladimir O.; Vovk, Andriy Ya.; Malkinski, Leszek; O'Connor, Charles J.; Wang, Zhenjun; Tang, Jinke

    2004-10-01

    The origin of anomalous negative magnetoresistance and its temperature dependence in polycrystalline Ni -Mn-Ga films prepared by pulse laser deposition was studied. The investigation of structural, transports, magnetic, and ferromagnetic resonance properties of the films suggests contributions of different mechanisms in magnetotransport. At low magnetic fields the main contribution to magnetoresistance is due to the transport between the areas with different orientation of magnetic moments, while at high fields it is an electron scattering of in spin-disordered areas.

  8. Anomalous Heating and Plasmoid Formation in a Driven Magnetic Reconnection Experiment

    CERN Document Server

    Hare, J D; Lebedev, S V; Loureiro, N F; Ciardi, A; Burdiak, G C; Chittenden, J P; Clayson, T; Garcia, C; Niasse, N; Robinson, T; Smith, R A; Stuart, N; Suzuki-Vidal, F; Swadling, G F; Ma, J; Wu, J; Yang, Q

    2016-01-01

    We present a detailed study of magnetic reconnection in a quasi-two-dimensional pulsed-power driven laboratory experiment. Oppositely directed magnetic fields $(B=3$ T), advected by supersonic, sub-Alfv\\'enic carbon plasma flows $(V_{in}=50$ km/s), are brought together and mutually annihilate inside a thin current layer ($\\delta=0.6$ mm). Temporally and spatially resolved optical diagnostics, including interferometry, Faraday rotation imaging and Thomson scattering, allow us to determine the structure and dynamics of this layer, the nature of the inflows and outflows and the detailed energy partition during the reconnection process. We measure high electron and ion temperatures $(T_e=100$ eV, $T_i=600$ eV), far in excess of what can be attributed to classical (Spitzer) resistive and viscous dissipation. We observe the repeated formation and ejection of plasmoids, which we interpret as evidence of two-fluid effects in our experiment.

  9. Magnetic evolution and anomalous Wilson transition in diagonal phosphorene nanoribbons driven by strain

    Science.gov (United States)

    Zhang, Shuai; Li, Chong; Xiao Guo, Zheng; Cho, Jun-Hyung; Su, Wan-Sheng; Jia, Yu

    2015-07-01

    Inducing magnetism in phosphorene nanoribbons (PNRs) is critical for practical applications. However, edge reconstruction and Peierls distortion prevent PNRs from becoming highly magnetized. Using first-principles calculations, we find that relaxed oxygen-saturated diagonal-PNRs (O-d-PNRs) realize stable spin-polarized antiferromagnetic (AFM) coupling, and the magnetism is entirely localized at the saturated edges. The AFM state is quite stable under expansive and limited compressive strain. More importantly, not only does the irreversible Wilson transition occur when applying strain, but the nonmagnetic (NM) metal phase (a new ground state) becomes more stable than the AFM state when the compressive strain exceeds -4%. The related stability and transition mechanism are demonstrated by dual tuning of the geometric and electronic structures, which manifests as a geometric deviation from a honeycomb to an orthorhombic-like structure and formation of P-py bonding (P-pz nonbonding) from P-pz nonbonding (P-py antibonding) because of the increase of the proportion of the P-py (P-pz) orbital.

  10. Anomalous magnetic hyperfine structure of the 229Th ground-state doublet in muonic atoms

    Science.gov (United States)

    Tkalya, E. V.

    2016-07-01

    The magnetic hyperfine (MHF) splitting of the ground and low-energy 3 /2+(7.8 ±0.5 eV) levels in the 229Th nucleus in the muonic atom (μ1S1 /2 -229Th) * is calculated considering the distribution of the nuclear magnetization in the framework of the collective nuclear model with wave functions of the Nilsson model for the unpaired neutron. It is shown that (a) deviation of the MHF structure of the isomeric state exceeds 100% from its value for a pointlike nuclear magnetic dipole (the order of sublevels is reversed); (b) partial inversion of levels of the 229Th ground-state doublet and spontaneous decay of the ground state to the isomeric state occur; (c) the E 0 transition, which is sensitive to differences in the mean-square charge radii of the doublet states, is possible between mixed sublevels with F =2 ; and (d) MHF splitting of the 3 /2+ isomeric state may be in the optical range for certain values of the intrinsic gK factor and a reduced probability of a nuclear transition between the isomeric and the ground states.

  11. Electrodeposition of nanostructured CoNi thin films and their anomalous infrared properties

    International Nuclear Information System (INIS)

    Different composition, thickness and structure of CoNi thin films supported on glassy carbon were prepared by electrochemical codeposition. Potential step method was applied to prepare CoNi thin films with different composition which was controlled by varying the concentration ratio of Co2+/Ni2+ (x:y) in the deposition solution, thus this type of CoNi thin film was defined as CoNi(x:y). Nevertheless, CoNi thin films with different thickness and structure (denoted as CoNi(n)) were synthesized in a fixed Co2+/Ni2+ solution under cyclic voltammetric conditions by varying the cyclic numbers (n) within a defined potential range. AES and EDS analysis revealed that the atomic ratio of Co/Ni in the film (including both outer and inner layer) was in good accordance with the initial Co2+/Ni2+ ratio. XRD investigation indicated that the CoNi(20:0) and CoNi(15:5) thin films were hexagonal closed-packed (hcp) structure, however, the CoNi(10:10), CoNi(5:15) and CoNi(0:20) thin films were face centered cubic (fcc) structure. SEM studies demonstrated that the CoNi(x:y) thin films were uniformly composed of irregular nanoparticles. In the case of CoNi(n), with n increasing, the structure of nanoparticles inside the CoNi thin films underwent a transition from imperfectly spherical particles to multiform particles, and finally to irregular polyhedral particles, accompany with an increase of average size. In situ FTIR reflection spectroscopic studies demonstrated that the mainly chemisorbed CO species (COad) on CoNi(x:y) surfaces were transferred from linearly bonded CO (COL) to bridge bonded CO (COB) as a function of the content of Ni and the crystal phase structure of CoNi thin films. CoNi(x:y) and CoNi(n) thin films all exhibited anomalous IR properties, corresponding respectively to abnormal IR effects (AIREs), Fano-like IR effects and surface-enhanced IR absorption effects. AIREs characterized mostly with inversion of IR band was found on CoNi(x:y), CoNi(4), CoNi(8) thin films

  12. Anomalous bootstrap current due to drift waves

    International Nuclear Information System (INIS)

    An anomalous parallel current driven by radial flux in tokamak is discussed. Drift waves, which cause an anomalous cross field diffusion, can generate a parallel current in a sheared magnetic field, if the fluctuation level has radial dependence. (author)

  13. Saturation properties of nuclear matter in the presence of strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, Z. [Shiraz University, Department of Physics and Biruni Observatory, Shiraz (Iran, Islamic Republic of); Bordbar, G.H. [Shiraz University, Department of Physics and Biruni Observatory, Shiraz (Iran, Islamic Republic of); Center for Excellence in Astronomy and Astrophysics (CEAA-RIAAM)-Maragha, P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)

    2016-05-15

    Different saturation properties of cold symmetric nuclear matter in strong magnetic field have been considered. We have seen that for magnetic fields about B>3 x 10{sup 17} G, for both cases with and without nucleon anomalous magnetic moments, the saturation density and saturation energy grow by increasing the magnetic field. It is indicated that the magnetic susceptibility of symmetric nuclear matter becomes negative showing the diamagnetic response especially at B<3 x 10{sup 17} G. We have found that for the nuclear matter, the magnitude of orbital magnetization reaches higher values comparing to the spin magnetization. Our results for the incompressibility show that at high enough magnetic fields, i.e. B>3 x 10{sup 17} G, the softening of the equation of state caused by Landau quantization is overwhelmed by stiffening due to the magnetization of nuclear matter. We have shown that the effects of strong magnetic field on nuclear matter may affect the constraints on the equation of state of symmetric nuclear matter obtained by applying the experimental observables. (orig.)

  14. Magnetic Properties of 3D Printed Toroids

    Science.gov (United States)

    Bollig, Lindsey; Otto, Austin; Hilpisch, Peter; Mowry, Greg; Nelson-Cheeseman, Brittany; Renewable Energy; Alternatives Lab (REAL) Team

    Transformers are ubiquitous in electronics today. Although toroidal geometries perform most efficiently, transformers are traditionally made with rectangular cross-sections due to the lower manufacturing costs. Additive manufacturing techniques (3D printing) can easily achieve toroidal geometries by building up a part through a series of 2D layers. To get strong magnetic properties in a 3D printed transformer, a composite filament is used containing Fe dispersed in a polymer matrix. How the resulting 3D printed toroid responds to a magnetic field depends on two structural factors of the printed 2D layers: fill factor (planar density) and fill pattern. In this work, we investigate how the fill factor and fill pattern affect the magnetic properties of 3D printed toroids. The magnetic properties of the printed toroids are measured by a custom circuit that produces a hysteresis loop for each toroid. Toroids with various fill factors and fill patterns are compared to determine how these two factors can affect the magnetic field the toroid can produce. These 3D printed toroids can be used for numerous applications in order to increase the efficiency of transformers by making it possible for manufacturers to make a toroidal geometry.

  15. Anomalous cross-field current and fluctuating equilibrium of magnetized plasmas

    DEFF Research Database (Denmark)

    Rypdal, K.; Garcia, O.E.; Paulsen, J.V.

    1997-01-01

    It is shown by simple physical arguments and fluid simulations that electrostatic flute-mode fluctuations can sustain a substantial cross-field current in addition to mass and energy transport. The simulations show that this current determines essential features of the fluctuating plasma equilibr......It is shown by simple physical arguments and fluid simulations that electrostatic flute-mode fluctuations can sustain a substantial cross-field current in addition to mass and energy transport. The simulations show that this current determines essential features of the fluctuating plasma...... equilibrium, and explain qualitatively the experimental equilibria and the coherent flute-mode structures observed in a simple magnetized torus....

  16. Pair Production and Vacuum Polarization of Vector Particles with Electric Dipole Moments and Anomalous Magnetic Moments

    CERN Document Server

    Kruglov, S I

    2001-01-01

    The matrix, 8-component Dirac-like form of P-odd equations for boson fields of spins 1 and 0 are obtained and the GL(2,c) symmetry group of equations is derived. We found exact solutions of the field equation for vector particles with arbitrary electric and magnetic moments in external constant and uniform electromagnetic fields. The differential probability of pair production of vector particles with the EDM and AMM by an external constant and uniform electromagnetic field has been found using the exact solutions. We have calculated the imaginary and real parts of the electromagnetic field Lagrangian that takes into account the vacuum polarization of vector particles.

  17. Pair Production and Vacuum Polarization of Vector Particles with Electric Dipole Moments and Anomalous Magnetic Moments

    OpenAIRE

    Kruglov, S. I.

    2001-01-01

    The matrix, 8-component Dirac-like form of P-odd equations for boson fields of spins 1 and 0 are obtained and the GL(2,c) symmetry group of equations is derived. We found exact solutions of the field equation for vector particles with arbitrary electric and magnetic moments in external constant and uniform electromagnetic fields. The differential probability of pair production of vector particles with the EDM and AMM by an external constant and uniform electromagnetic field has been found usi...

  18. Magnetic susceptibility properties of polluted soils

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An investigation of magnetic properties using magnetic susceptibility (X) and frequency-dependent susceptibility (Xfd) was conducted on representative modern pollutants, which include smelted slag dust, automobile exhaust dust and coal ash. Their magnetic susceptibility values are more than 500×10-8 m3/kg, and frequency-dependent susceptibility values less than 3%, indicating that ample ferrimagnetic and scanty superparamagnetic grains occurred in the studied pollutants. Similar to the artificially synthetic polluted soils, the industrially-polluted soils display a negative relationship between magnetic susceptibility and frequency-dependent susceptibility. However, the unpolluted soils, e.g. the Quaternary loess in the Chinese Loess Plateau, show a positive relationship between them. In this note, we propose a convenient and effective approach for identifying the polluted soils.

  19. Magnetic Ground State Properties of Transition Metals

    DEFF Research Database (Denmark)

    Andersen, O. K.; Madsen, J.; Poulsen, U. K.;

    1977-01-01

    We review a simple one-electron theory of the magnetic and cohesive properties of ferro- and nearly ferromagnetic transition metals at 0 K. The theory is based on the density functional formalism, it makes use of the local spin density and atomic sphere approximations and it may, with further app...

  20. Magnetic properties of group VIB hexacarbonyls

    International Nuclear Information System (INIS)

    Careful measurements of the magnetic susceptibilities of group VIB metal hexacarbonyls show an ideal diamagnetic behaviour. The properties of W(CO)6, together with the relatively low price, lead to the suggestion of W(CO)6 as a new calibration standard for the diamagnetic region. (Author)

  1. Magnetic Properties of Nanoparticles of Antiferromagnetic Materials

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine; Bødker, Franz;

    2003-01-01

    The magnetic properties of antiferromagnetic nanoparticles have been studied by Mossbauer spectroscopy and neutron scattering. Temperature series of Mossbauer spectra of non-interacting, superparamagnetic hematite nanoparticles were fitted by use of the Blume-Tjon relaxation model. It has been...

  2. Magnetic properties of polymer bonded nanocrystalline powder

    Directory of Open Access Journals (Sweden)

    P. Sakiewicz

    2007-01-01

    Full Text Available Purpose: The aim of this paper was to develop a dielectromagnetic based on nanocrystalline Fe73.5Cu1Nb3Si13.5B9powder bonded with organo-silicon polymer and to investigate the powder particle size and content of polymerresponse of the magnetic properties.Design/methodology/approach: The dynamic magnetic properties at the frequency range from 50 Hz up to100 kHz of nanocrystalline iron based powder cores were measured using computerized hysteresis loop tracerRemacomp C-100 and Ferrometr device.Findings: It was found from the experimental studies, that nanocrystalline powder cores proved to be suitablefor high frequency applications. Their frequency dependences are comparable to that of carbonyl iron powdercores but shows smaller power losses.Research limitations/implications: Further studies should be undertaken in order to produce high densitycomposites with good soft magnetic properties and to find a good compromise between mechanical andmagnetic properties for power electronics applications.Practical implications: Developed nanocrystalline powder cores with permeability’s below 100 are potentialcandidates for a variety of industrial applications, such as electromagnetic interference filters, radio frequencycoupling devices, filter inductors and radio frequency tuning cores.Originality/value: Soft magnetic materials have recently regained interest as inductive component whichis a result of better raw materials, more developed technologies and a need for the materials from electricalmicromotors and low power motors for automation, robotics and other equipments. The present studycomplements and extends earlier investigations of polymer bonded powders.

  3. Anomalous origin of the left circumflex coronary artery from the pulmonary artery. A very rare congenital anomaly in an adult patient diagnosed by cardiovascular magnetic resonance

    OpenAIRE

    Giannitsis Evangelos; Ringwald Gerd; Korosoglou Grigorios; Katus Hugo A

    2008-01-01

    Abstract Here we report for the first time on the diagnostic potential of cardiovascular magnetic resonance (CMR) to delineate the proximal course of an anomalous left circumflex coronary artery (LCX) originating from the right pulmonary artery in an adult patient with no other form of congenital heart disease. The patient was referred to our institution due to exertional chest discomfort. X-Ray coronary angiography showed a normal left anterior descending coronary artery (LAD) and right coro...

  4. Toroidal resonance: relation to pygmy mode, vortical properties and anomalous deformation splitting

    CERN Document Server

    Nesterenko, V O; Repko, A; Kleinig, W; Reinhard, P -G

    2016-01-01

    We review a recent progress in investigation of the isoscalar toroidal dipole resonance (TDR). A possible relation of the TDR and low-energy dipole strength (also called a pygmy resonance) is analyzed. It is shown that the dipole strength in the pygmy region can by understood as a local manifestation of the collective vortical toroidal motion at the nuclear surface. Application of the TDR as a measure of the nuclear dipole vorticity is discussed. Finally, an anomalous splitting of the TDR in deformed nuclei is scrutinized.

  5. Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars.

    Science.gov (United States)

    van Saders, Jennifer L; Ceillier, Tugdual; Metcalfe, Travis S; Aguirre, Victor Silva; Pinsonneault, Marc H; García, Rafael A; Mathur, Savita; Davies, Guy R

    2016-01-14

    A knowledge of stellar ages is crucial for our understanding of many astrophysical phenomena, and yet ages can be difficult to determine. As they become older, stars lose mass and angular momentum, resulting in an observed slowdown in surface rotation. The technique of 'gyrochronology' uses the rotation period of a star to calculate its age. However, stars of known age must be used for calibration, and, until recently, the approach was untested for old stars (older than 1 gigayear, Gyr). Rotation periods are now known for stars in an open cluster of intermediate age (NGC 6819; 2.5 Gyr old), and for old field stars whose ages have been determined with asteroseismology. The data for the cluster agree with previous period-age relations, but these relations fail to describe the asteroseismic sample. Here we report stellar evolutionary modelling, and confirm the presence of unexpectedly rapid rotation in stars that are more evolved than the Sun. We demonstrate that models that incorporate dramatically weakened magnetic braking for old stars can--unlike existing models--reproduce both the asteroseismic and the cluster data. Our findings might suggest a fundamental change in the nature of ageing stellar dynamos, with the Sun being close to the critical transition to much weaker magnetized winds. This weakened braking limits the diagnostic power of gyrochronology for those stars that are more than halfway through their main-sequence lifetimes.

  6. The quantum anomalous Hall effect

    OpenAIRE

    LIU, CHAO-XING; Zhang, Shou-Cheng; Qi, Xiao-Liang

    2015-01-01

    The quantum anomalous Hall effect is defined as a quantized Hall effect realized in a system without external magnetic field. Quantum anomalous Hall effect is a novel manifestation of topological structure in many-electron systems, and may have potential applications in future electronic devices. In recent years, quantum anomalous Hall effect has been proposed theoretically and realized experimentally. In this review article, we provide a systematic overview of the theoretical and experimenta...

  7. Magnetic topological insulator and quantum anomalous Hall effect%磁性拓扑绝缘体与量子反常霍尔效应

    Institute of Scientific and Technical Information of China (English)

    翁红明; 戴希; 方忠

    2014-01-01

    量子反常霍尔绝缘体,有时也被称为陈数绝缘体,是不同于普通绝缘体和拓扑绝缘体的一类新的二维绝缘体,该体系具有可被实验观测的特殊物理性质-量子反常霍尔效应。该体系的物态不能用朗道对称性破缺理论来描写,而要用到拓扑物态的概念。它的发现也经历了从反常霍尔效应的内秉物性阐释,到量子自旋霍尔效应与拓扑绝缘体的发现,再到磁性拓扑绝缘体的理论预测与实现,并最终成功实验观测的漫长过程。由于量子反常霍尔效应的实现不需要外加磁场,而此时样品的边缘态可以被看成一根无能耗的理想导线,因此人们对于其将来可能的应用充满了期待。本文将从理论的角度简单综述该领域的发展历程、基本概念、以及相关的材料系统。%Quantum anomalous Hall insulator, also called as Chern insulator, is a new two-dimensional insulator distinguished from normal insulator and topological insulator by possess-ing a special and experimentally observable physical property-quantum anomalous Hall effect (QAHE). This is a novel quantum state can not be described by the Landau symmetry breaking theory but by the concept of topology of band structure. Its discovery experienced a long his-tory: from the explanation of intrinsic contribution to anomalous Hall effect, to the discovery of quantum spin Hall effect and topological insulator, to the prediction and realization of magnetic topological insulator, and finally to the experimental observation of it. Since QAHE does not require external magnetic field and has dissipationless (without lost of kinetic energy that being transferred to thermal energy) conducting edge states which can be used as an ideal conducting wire, it is expected to have various potential applications in future. This paper gives a review of this field on its history, basic concepts and related materials from the theoretical point of view.

  8. Magnetic properties of pelagic marine carbonates

    Science.gov (United States)

    Roberts, Andrew P.; Florindo, Fabio; Chang, Liao; Heslop, David; Jovane, Luigi; Larrasoaña, Juan C.

    2013-12-01

    Pelagic carbonates are deposited far from continents, usually at water depths of 3000-6000 m, at rates below 10 cm/kyr, and are a globally important sediment type. Recent advances, with recognition of widespread preservation of biogenic magnetite (the inorganic remains of magnetotactic bacteria), have fundamentally changed our understanding of the magnetic properties of pelagic carbonates. We review evidence for the magnetic minerals typically preserved in pelagic carbonates, the effects of magnetic mineral diagenesis on paleomagnetic and environmental magnetic records of pelagic carbonates, and what magnetic properties can tell us about the open-ocean environments in which pelagic carbonates are deposited. We also discuss briefly late diagenetic remagnetisations recorded by some carbonates. Despite recent advances in our knowledge of these phenomena, much remains undiscovered. We are only at early stages of understanding how biogenic magnetite gives rise to paleomagnetic signals in sediments and whether it carries a poorly understood biogeochemical remanent magnetisation. Recently developed techniques have potential for testing how different magnetotactic bacterial species, which produce different magnetite morphologies, respond to changing nutrient and oxygenation conditions. Future work needs to test whether it is possible to develop proxies for ancient nutrient conditions from well-calibrated modern magnetotactic bacterial occurrences. A tantalizing link between giant magnetofossils and Paleogene hyperthermal events needs to be tested; much remains to be learned about the relationship between climate and the organisms that biomineralised these large and novel magnetite morphologies. Rather than being a well-worn subject that has been studied for over 60 years, the magnetic properties of pelagic carbonates hold many secrets that await discovery.

  9. Anomalous magnetic reordering in magnetodielectric terbium iron garnet at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lahoubi, Mahieddine, E-mail: mlahoubi@hotmail.fr [Department of Physics, Laboratory L.P.S., Faculty of Sciences, Badji Mokhtar-Annaba University, PO Box -12, 23000 Annaba (Algeria); Ouladdiaf, Bachir [Institut Laue Langevin, BP 156, F-38042 Grenoble Cedex 9 (France)

    2015-01-01

    The paper deals with five topics: i) the single three-dimensional irreductible representation (Γ{sub 4g}=T{sub 1g}) of the paramagnetic space group Ia3{sup ¯}d No. 230 is chosen according to the representation analysis of Bertaut for the interpretation of the neutron powder diffraction experiments performed on terbium iron garnet (Tb{sub 3}Fe{sub 5}O{sub 12}); ii) the use of the method of the “symmetry lowering device” of Bertaut in order to select the appropriate rhombohedral subgroup of Ia3{sup ¯}d which allows to deal with the case where the cubic description provides an incomplete answer to the changes observed below 160 K in the ferrimagnetic structure around the [1 1 1] axis from the Néel model toward the “double umbrella” observed at 13 K; iii) the magnetic modes belonging to the one-dimensional irreductible representation A{sub 2g} of the highest rhombohedral subgroup R3{sup ¯}c No. 167 are able to describe the occurrence of its anisotropic character which steeply increases below 160 K due to the concomitant anisotropic effects; iv) the broad anomaly observed near 54 K in the temperature dependences of the components of both sublattices of the Tb{sup 3+} ions in the Wyckoff positions (6e) and (6e′) is explained partially on the basis of the concept of Belov of the strong paraprocess which has been termed “exchange-enhanced paramagnetism” at the so-called “low-temperature point” (T{sub B}); v) the results are related to the magnetodielectric effect in low magnetic field and to the significant coupling between exchange magnons and ligand-field excitations reported recently in this compound. - Highlights: • We examine the changes of the “double umbrella” in TbIG using neutron diffraction. • Symmetry arguments of Bertaut clarify suitable rhombohedral space group at 13 K. • Its opening leads to an increasing of anisotropy of the Tb components below 160 K. • The “low-temperature point” of Belov explains partly its intricate

  10. A study of magnetic fluctuations and their anomalous scaling in the solar wind: the Ulysses fast-latitude scan

    Directory of Open Access Journals (Sweden)

    c. Pagel

    2001-01-01

    Full Text Available The solar wind is a highly turbulent and intermittent medium at frequencies between 10-4 and 10-1 Hz. Power spectra are used to look at fluctuations in the components of the magnetic field at high frequencies over a wide range of latitudes. Results show steady turbulence in the polar regions of the Sun and a more varied environment in the equatorial region. The magnetic field fluctuations exhibit anomalous scaling at high frequencies. Various models have been proposed in an attempt to better understand the scaling nature of such fluctuations in neutral fluid turbulence. We have used the Ulysses fast latitude scan data to perform a wide ranging comparison of three such models on the solar wind magnetic field data: the well-known P model, in both its Kolmogorov and Kraichnan forms, the lognormal cascade model and a model adapted from atmospheric physics, the G infinity model. They were tested by using fits to graphs of the structure function exponents g(q, by making a comparison with a non-linear measure of the deviation of g(q from the non-intermittent straight line, and by using extended self similarity technique, over a large range of helio-latitudes. Tests of all three models indicated a high level of intermittency in the fast solar wind, and showed a varied structure in the slow wind, with regions of apparently little intermittency next to regions of high intermittency, implying that the slow wind has no uniform origin. All but one of the models performed well, with the lognormal and Kolmogorov P model performing the best over all the tests, indicating that inhomogeneous energy transfer in the cascade is a good description. The Kraichnan model performed relatively poorly, and the overall results show that the Kraichnan model of turbulence is not well supported over the frequency and distance ranges of our data set. The G infinity model fitted the results surprisingly well and showed that there may very well be important universal geometrical

  11. Functional behavior of the anomalous magnetic relaxation observed in melt-textured YBa2Cu3O7-δ samples showing the paramagnetic Meissner effect

    Science.gov (United States)

    Dias, F. T.; Vieira, V. N.; Garcia, E. L.; Wolff-Fabris, F.; Kampert, E.; Gouvêa, C. P.; Schaf, J.; Obradors, X.; Puig, T.; Roa, J. J.

    2016-10-01

    We have studied the functional behavior of the field-cooled (FC) magnetic relaxation observed in melt-textured YBa2Cu3O7-δ (Y123) samples with 30 wt% of Y2Ba1Cu1O5 (Y211) phase, in order to investigate anomalous paramagnetic moments observed during the experiments. FC magnetic relaxation experiments were performed under controlled conditions, such as cooling rate and temperature. Magnetic fields up to 5T were applied parallel to the ab plane and along the c-axis. Our results are associated with the paramagnetic Meissner effect (PME), characterized by positive moments during FC experiments, and related to the magnetic flux compression into the samples. After different attempts our experimental data could be adequately fitted by an exponential decay function with different relaxation times. We discuss our results suggesting the existence of different and preferential flux dynamics governing the anomalous FC paramagnetic relaxation in different time intervals. This work is one of the first attempts to interpret this controversial effect in a simple analysis of the pinning mechanisms and flux dynamics acting during the time evolution of the magnetic moment. However, the results may be useful to develop models to explain this interesting and still misunderstood feature of the paramagnetic Meissner effect.

  12. Microwave absorbing properties and magnetic properties of different carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The microwave absorbing properties and magnetic properties of as-grown Fe-filled carbon nanotubes (CNTs), annealed Fe-filled CNTs, and multi-walled CNTs were studied. Vibrating sample magnetometer results showed that the annealed Fe-filled CNTs have the weakest coercivity and strongest saturation magnetization among the three types CNTs, due to the presence of more ferromagnetic α-Fe nanowires. After annealing, the values increased to 291.0 Oe and 28.0 emu/g and the samples showed excellent microwave absorbing properties. The reflection loss was over 5 dB between 11.6 GHz and 18 GHz with a maximum value of 10.8 dB for annealed Fe-filled CNTs (1.1 wt%)/epoxy composite.

  13. Microwave absorbing properties and magnetic properties of different carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    GUI XuChun; WANG KunLin; WEI JinQuan; L(U) RuiTao; SHU QinKe; JIA Yi; WANG Chen; ZHU HongWei; WU DeHai

    2009-01-01

    The microwave absorbing properties and magnetic properties of as-grown Fe-filled carbon nanotubes (CNTs), annealed Fe-filled CNTs, and multi-walled CNTs were studied. Vibrating sample magnetometer results showed that the annealed Fe-filled CNTs have the weakest coercivity and strongest saturation magnetization among the three types CNTs, due to the presence of more ferromagnetic α-Fe nanowires.After annealing, the values increased to 291.00e and 28.0 emu/g and the samples showed excellent microwave absorbing properties. The reflection loss was over 5 dB between 11.6 GHz and 18 GHz with a maximum value of 10.8 dB for annealed Fe-filled CNTs (1.1 wt%)/epoxy composite.

  14. Electronic structure, cohesive, and magnetic properties of the actinide-iridium Laves phases

    International Nuclear Information System (INIS)

    The electronic structure of the isostructural AIr2 systems (A = Th, Pa, U, Np, Pu, and Am) has been obtained by means of the scalar relativistic and fully relativistic linear muffin-tin orbital techniques. Ground-state properties such as lattice constants and onset of magnetic order have been calculated and compared with measured data. The hybridization between the actinide 5f and the ligand 5d states and the direct 5f wave-function overlap are found to be of comparable importance for the bandwidth of the itinerant 5f states. The anomalous paramagnetism of PuIr2 can be explained only by a fully relativistic treatment

  15. Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. I. Kinetic equation and anomalous Hall and spin-Hall effects

    Science.gov (United States)

    Morawetz, K.

    2015-12-01

    The coupled kinetic equation for density and spin Wigner functions is derived including spin-orbit coupling, electric and magnetic fields, and self-consistent Hartree mean fields suited for SU(2) transport. The interactions are assumed to be with scalar and magnetic impurities as well as scalar and spin-flip potentials among the particles. The spin-orbit interaction is used in a form suitable for solid state physics with Rashba or Dresselhaus coupling, graphene, extrinsic spin-orbit coupling, and effective nuclear matter coupling. The deficiencies of the two-fluid model are worked out consisting of the appearance of an effective in-medium spin precession. The stationary solution of all these systems shows a band splitting controlled by an effective medium-dependent Zeeman field. The self-consistent precession direction is discussed and a cancellation of linear spin-orbit coupling at zero temperature is reported. The precession of spin around this effective direction caused by spin-orbit coupling leads to anomalous charge and spin currents in an electric field. Anomalous Hall conductivity is shown to consist of the known results obtained from the Kubo formula or Berry phases and a symmetric part interpreted as an inverse Hall effect. Analogously the spin-Hall and inverse spin-Hall effects of spin currents are discussed which are present even without magnetic fields showing a spin accumulation triggered by currents. The analytical dynamical expressions for zero temperature are derived and discussed in dependence on the magnetic field and effective magnetizations. The anomalous Hall and spin-Hall effect changes sign at higher than a critical frequency dependent on the relaxation time.

  16. Magnetic properties of artificially synthesized ferritins

    Science.gov (United States)

    Kim, B. J.; Lee, H. I.; Cho, S.-B.; Yoon, S.; Suh, B. J.; Jang, Z. H.; St. Pierre, T. G.; Kim, S.-W.; Kim, K.-S.

    2005-05-01

    Human ferritin homopolymers with H or L subunits (rHF and rLF) were genetically engineered in E coli. Apoferritins were then reconstituted with 2000 Fe atoms. A big difference was observed in the rates of iron uptake, whereas the mean core size was similar in rHF and rLF. Magnetization of the recombinant human ferritins were measured as functions of temperature and field. The blocking temperature TB(H) at low fields is considerably higher in rLF than in rHF. From the fit of M(H ) data to a modified Langevin function: M(H )=M0L(μpH/kBT)+χaH, the effective magnetic moment μp is found to be much larger in rLF than in rHF. Experimental data demonstrate that the magnetic properties, in particular, the uncompensated spins of ferritin core are related to the biomineralization process in ferritins.

  17. Properties of GRB Lightcurves from Magnetic Reconnection

    CERN Document Server

    Beniamini, Paz

    2015-01-01

    The energy dissipation mechanism within Gamma ray bursts' (GRBs) ultra-relativistic outflows that drive the prompt $\\gamma$-ray emission remains uncertain. Two leading candidates are internal shocks and magnetic reconnection. While the emission from internal shocks has been extensively studied, that from reconnection still has few quantitative predictions. We study the prompt GRB emission from magnetic reconnection and compare its expected temporal and spectral properties to observations. The main difference from internal shocks is that for magnetic reconnection one expects relativistic bulk motions with a Lorentz factor of $\\Gamma'\\gtrsim$a few in the mean rest frame of the outflow - the comoving frame. We consider a thin spherical shell (or reconnection layer) expanding at a bulk Lorentz factor $\\Gamma\\gg 1$ in which the emitting material moves with $\\Gamma'$ in the comoving frame along this layer in two anti-parallel directions (e.g. of the reconnecting field lines). The resulting relativistic beaming of t...

  18. Synthesis and Properties of Magnetic Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Sixin LI; Jiancheng ZHANG; Yue SHEN; Bo NI; Jingang ZHANG

    2006-01-01

    The uniform mesoporous SBA-15 consisting of SiO2 with long-range channels offers an excellent host material to synthesize or assemble the magnetic nanocomposites, such as Fe, Ni.In this paper, highly dispersed and uniform iron nanoparticles were incorporated into the pore channels of SBA-15 through a newly developed strategy in which some kinds of coupling agents were used to entrap the nanoparticles into the silica framework.The X-ray diffraction(XRD), fourier transmission infrared spectroscopy(FTIR), high-resolution transmission electronic microscopy(HRTEM)and energy dispersive X-ray spectroscopy(EDX)were performed to further identify the successful incorporation and grafting of iron. Compared with other ordinary non-assembled magnetic nanoparticles, the assembled Fe nanoparticles with the diameter even in the size range of 5~6 nm still have better magnetic properties.

  19. Electronic Structure and Magnetic Properties of Rh13 Cluster with Three Possible Symmetries

    Institute of Scientific and Technical Information of China (English)

    KUANG Xiang-Jun

    2006-01-01

    Electronic and magnetic properties of 13-atom Rh clusters with three possible high symmetry geometries have been studied by using the first-principles DV-LSD method. An anoma- lous symmetry dependence of the cluster magnetism was found that the total magnetic moment of the icosahedral Rh13 cluster is smaller than that of the other two lower-symmetry clusters in a wide range of interatomic spacings. An energy difference is identified to explain this anomalous relationship, which has been found to be also useful for judging whether the broadening technique is correctly used and whether multiple input potentials must be used to reach the actual ground state in the LSD calculations. The calculated results are compared and discussed with those of previous theory and recent experiment. The actual geometry of the Rh13 cluster is suggested to be a distorted icosahedron.

  20. Magnetic Properties of Friction Stir Processed Composite

    Science.gov (United States)

    Das, Shamiparna; Martinez, Nelson Y.; Das, Santanu; Mishra, Rajiv S.; Grant, Glenn J.; Jana, Saumyadeep; Polikarpov, Evgueni

    2016-07-01

    Of the many existing inspection or monitoring systems, each has its own advantages and drawbacks. These systems are usually comprised of semi-remote sensors that frequently cause difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites, so that embedding can be achieved in virtually any component part and periodically can be interrogated by a reading device. The "reinforcement rich" processed areas can then be used to record properties such as strain, temperature, and stress state, to name a few, depending on the reinforcement material. Friction stir processing was used to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum matrix. The aim was to develop a composite that produces strain in response to a varying magnetic field. Reinforcements were distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer. A simple and cost-effective setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and the processing route was modified to improve the magnetic response.

  1. The critical properties of magnetic films

    International Nuclear Information System (INIS)

    Within the framework of the transverse spin-1/2 Ising model and by using the effective field theory with a probability distribution technique that accounts for the self spin correlations, we have studied the critical properties of an L-layer film of simple cubic symmetry in which the exchanges strength are assumed to be different from the bulk values in NS surface layers. We derive and illustrate the expressions for the phase diagrams, order parameter profiles and susceptibility. In such films, the critical temperature can shift to either lower or higher temperature compared with the corresponding bulk value. We calculate also some magnetic properties of the film, such as the layer magnetizations, their averages and their profiles and the longitudinal susceptibility of the film. The film longitudinal susceptibility still diverges at the film critical temperature as does the bulk longitudinal susceptibility.

  2. Monte Carlo study of nanowire magnetic properties

    Institute of Scientific and Technical Information of China (English)

    R.Masrour; L.Bahmad; A.Benyoussef

    2013-01-01

    In this work,we use Monte Carlo simulations to study the magnetic properties of a nanowire system based on a honeycomb lattice,in the absence as well as in the presence of both an external magnetic field and crystal field.The system is formed with NL layers having spins that can take the values σ =+1/2 and S =+1,0.The blocking temperature is deduced,for each spin configuration,depending on the crystal field A.The effect of the exchange interaction coupling Jp between the spin configurations σ and S is studied for different values of temperature at fixed crystal field.The established ground-state phase diagram,in the plane (Jp,A),shows that the only stable configurations are:(1/2,0),(1/2,+1),and (1/2,-1).The thermal magnetization and susceptibility are investigated for the two spin configurations,in the absence as well as in the presence of a crystal field.Finally,we establish the hysteresis cycle for different temperature values,showing that there is almost no remaining magnetization in the absence of the external magnetic field,and that the studied system exhibits a super-paramagnetic behavior.

  3. Suppression of the Neoclassical Tearing Modes in Tokamaks under Anomalous Transverse Transport Conditions when the Magnetic Well Effect Predominates over the Bootstrap Drive

    International Nuclear Information System (INIS)

    A study is made of the suppression of neoclassical tearing modes in tokamaks under anomalous transverse transport conditions when the magnetic well effect predominates over the bootstrap drive. It is stressed that the corresponding effect, which is called the compound suppression effect, depends strongly on the profiles of the electron and ion temperature perturbations. Account is taken of the fact that the temperature profile can be established as a result of the competition between anomalous transverse heat transport, on the one hand, and longitudinal collisional heat transport, longitudinal heat convection, longitudinal inertial transport, and transport due to the rotation of magnetic islands, on the other hand. The role of geodesic effects is discussed. The cases of competition just mentioned are described by the model sets of reduced transport equations, which are called, respectively, collisional, convective, inertial, and rotational plasmophysical models. The magnetic well is calculated with allowance for geodesic effects. It is shown that, for strong anomalous heat transport conditions, the contribution of the magnetic well to the generalized Rutherford equation for the island width W is independent of W not only in the collisional model (which has been investigated earlier) but also in the convective and inertial models and depends very weakly (logarithmically) on W in the rotational model. It is this weak dependence that gives rise to the compound effect, which is the subject of the present study. A criterion for the stabilization of neoclassical tearing modes by the compound effect at an arbitrary level of the transverse heat transport by electrons and ions is derived and is analyzed for two cases: when the electron heat transport and ion heat transport are both strong, and when the electron heat transport is strong and the ion heat transport is weak

  4. Anomalous temperature dependent photoluminescence properties of CdSxSe1-x quantum dots

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    CdSxSe1-x quantum dots were fabricated by a simple spin-coating heat volatilization method on InP wafer.Temperature dependent photoluminescence of CdSxSe1-x quantum dots was carried out in a range of 10-300 K.The integrated photoluminescence intensity revealed an anomalous behavior with increasing temperature in the range of 180-200 K.The band gap energy showed a redshift of 61.34 meV when the temperature increased from 10 to 300 K.The component ratio of S to Se in the CdSxSe1-x quantum dots was valued by both the X-ray diffraction data and photoluminescence peak energy at room temperature according to Vegard Law.Moreover,the parameters of the Varshni relation for CdS0.9Se0.1 materials were also obtained using photoluminescence peak energy as a function of temperature and the best-fit curve:α=(3.5 ± 0.1)10-4 eV/K,and β=210 ± 10 K (close to the Debye temperature θD of the material).

  5. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Echániz, T. [Departamento de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, UPV/EHU, Sarriena s/n, Leioa 48940 (Spain); Pérez-Sáez, R. B., E-mail: raul.perez@ehu.es; Tello, M. J. [Departamento de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, UPV/EHU, Sarriena s/n, Leioa 48940 (Spain); Instituto de Síntesis y Estudio de Materiales, Universidad del País Vasco, Apdo. 644, Bilbao 48080 (Spain)

    2014-09-07

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ε{sub peak} at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ε{sub peak} increases with the emission angle but its position, λ{sub peak}, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1.

  6. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    International Nuclear Information System (INIS)

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak εpeak at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that εpeak increases with the emission angle but its position, λpeak, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1

  7. Magnetic field properties caused by stress concentration

    Institute of Scientific and Technical Information of China (English)

    黄松岭; 李路明; 施克仁; 王晓凤

    2004-01-01

    Measurements of the effects of tensile stress on magnetic field properties, infrared thermography and acoustic emission of a cuboid sample with an elliptical hole in its center were presented. The tensile stress was applied perpendicularly to the sample by electro-tension machine according to a step-loading curve. The changes of the sample temperature was recorded by an infrared thermography system and the noise of domain reversal was inspected by two acoustic probes, which were placed on each end of the sample near the collets of the electro-tension machine,when the sample was in loading process. The magnetic fields on the surface of the sample were inspected with8mm lift-off when the loads were held. Valuable information about the changes of domains was obtained from analysis of acoustic emission signals in loading process. Infrared images of the sample provided complementary information about the state of the sample. The results show that stress concentration in ferromagnetic material affects the direction and structure of domain and generates net magnetic moment on its surface. The distribution and magnitude of the net magnetic moment are correlative with those of stress.

  8. Anomalous-viscosity current drive

    Science.gov (United States)

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  9. Anomalous transport from holography: Part I

    CERN Document Server

    Bu, Yanyan; Sharon, Amir

    2016-01-01

    We revisit the transport properties induced by the chiral anomaly in a charged plasma holographically dual to anomalous $U(1)_V\\times U(1)_A$ Maxwell theory in Schwarzschild-$AdS_5$. Off-shell constitutive relations for vector and axial currents are derived using various approximations generalising most of known in the literature anomaly-induced phenomena and revealing some new ones. In a weak external field approximation, the constitutive relations have all-order derivatives resummed into six momenta-dependent transport coefficient functions: the diffusion, the electric/magnetic conductivity, and three anomaly induced functions. The latter generalise the chiral magnetic and chiral separation effects. Nonlinear transport is studied assuming presence of constant background external fields. The chiral magnetic effect, including all order nonlinearity in magnetic field, is proven to be exact when the magnetic field is the only external field that is turned on. Non-linear corrections to the constitutive relations...

  10. Structural, magnetic, and transport properties of Fe-doped CoTiSb epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, N. Y.; Zhang, Y. Q.; Che, W. R.; Shan, R. [Shanghai Key Laboratory of Special Artificial Microstructure and Pohl Institute of Solid State Physics and School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Qin, J., E-mail: juan-qin@staff.shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China)

    2015-11-07

    Epitaxial intrinsic and Fe-doped CoTiSb thin films with C1{sub b} structure were grown on MgO(100) substrates by magnetron sputtering. The semiconducting-like behavior in both intrinsic and Fe-doped thin films was demonstrated by temperature dependence of longitudinal resistivity. The Fe-doped CoTiSb films with a wide range of doping concentrations can maintain semiconducting-like and magnetic properties simultaneously, while the semiconducting behavior is weakening with the increasing Fe concentration. For 21 at. % Fe-doped film, low lattice magnetic moment (around 0.65 μ{sub B}) and high resistivity (larger than 800 μΩ cm) are beneficial to its application as a magnetic electrode in spintronic devices. Anomalous Hall effect of 21 at. % Fe-doped film was also investigated and its behaviors can be treated well by recent-reported anomalous Hall scaling including the contribution of spin-phonon skew scattering.

  11. The New (g-2) Experiment: A proposal to measure the muon anomalous magnetic moment to +-0.14 ppm precision

    Energy Technology Data Exchange (ETDEWEB)

    Carey, R.M.; Lynch, K.R.; Miller, J.P.; Roberts, B.L.; Morse, W.M.; Semertzides, Y.K.; Druzhinin, V.P.; Khazin, B.I.; Koop, I.A.; Logashenko, I.; Redin, S.I.; /Boston U. /Brookhaven /Novosibirsk, IYF /Cornell U., CIHEP /Fermilab /Frascati /Illinois U., Urbana /James Madison U. /Groningen, KVI /KEK, Tsukuba /Kentucky U.

    2009-02-01

    We propose to measure the muon anomalous magnetic moment, a{sub {mu}}, to 0.14 ppm-a fourfold improvement over the 0.54 ppm precision obtained in the BNL experiment E821. The muon anomaly is a fundamental quantity and its precise determination will have lasting value. The current measurement was statistics limited, suggesting that greater precision can be obtained in a higher-rate, next-generation experiment. We outline a plan to use the unique FNAL complex of proton accelerators and rings to produce high-intensity bunches of muons, which will be directed into the relocated BNL muon storage ring. The physics goal of our experiment is a precision on the muon anomaly of 16 x 10{sup -11}, which will require 21 times the statistics of the BNL measurement, as well a factor of 3 reduction in the overall systematic error. Our goal is well matched to anticipated advances in the worldwide effort to determine the standard model (SM) value of the anomaly. The present comparison, {Delta}a{sub {mu}} (Expt: -SM) = (295 {+-} 81) x 10{sup -11}, is already suggestive of possible new physics contributions to the muon anomaly. Assuming that the current theory error of 51 x 10{sup -11} is reduced to 30 x 10{sup -11} on the time scale of the completion of our experiment, a future {Delta}a{sub {mu}} comparison would have a combined uncertainty of {approx} 34 x 10{sup -11}, which will be a sensitive and complementary benchmark for proposed standard model extensions. The experimental data will also be used to improve the muon EDM limit by up to a factor of 100 and make a higher-precision test of Lorentz and CPT violation. We describe in this Proposal why the FNAL complex provides a uniquely ideal facility for a next-generation (g-2) experiment. The experiment is compatible with the fixed-target neutrino program; indeed, it requires only the unused Booster batch cycles and can acquire the desired statistics in less than two years of running. The proton beam preparations are largely aligned

  12. Superconducting properties of a stoichiometric FeSe compound and two anomalous features in the normal state

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yoo Jang; Hong, Jong Beom; Min, Byeong Hun; Kwon, Yong Seung [Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Kyu Jun; Jung, Myung Hwa [Sogang University, Seoul (Korea, Republic of); Rhyee, Jong Soo [Kyunghee University, Seoul (Korea, Republic of)

    2011-08-15

    This paper reports the superconducting behavior of the tetragonal iron-chalcogenide superconductor FeSe. The electrical resistivity and the magnetic moment measurements confirmed its superconductivity with T{sup zero}{sub c} and T{sup mag}{sub c} of 9.4 K under ambient pressure. Electron probe macro analysis indicated that the sample had a stoichiometric Fe:Se ratio of 1:1. The Seebeck coefficient, which was 12.3 {mu}V/K at room temperature, changed to a negative value near 200 K, indicating it to be a two-carrier material. Above T{sub c}, the {rho}(T) curve revealed an 'S' shape, and d{rho}(T)/dT and d{sup 2}{rho}(T)/dT{sup 2} showed two anomalous features, one near T{sub an} = 30 K and the other near T{sup *} = 110 K. The Seebeck coefficient, S(T), also displays peculiar behavior near the T{sub an} and T{sup *}. We also report a rather smaller critical current density, J{sub c} = 10{sup 2} {approx} 10{sup 4} A/cm{sup 2}, compared to those observed for the other pnictides and doped chalcogenides.

  13. Superconducting properties of a stoichiometric FeSe compound and two anomalous features in the normal state

    International Nuclear Information System (INIS)

    This paper reports the superconducting behavior of the tetragonal iron-chalcogenide superconductor FeSe. The electrical resistivity and the magnetic moment measurements confirmed its superconductivity with Tzeroc and Tmagc of 9.4 K under ambient pressure. Electron probe macro analysis indicated that the sample had a stoichiometric Fe:Se ratio of 1:1. The Seebeck coefficient, which was 12.3 μV/K at room temperature, changed to a negative value near 200 K, indicating it to be a two-carrier material. Above Tc, the ρ(T) curve revealed an 'S' shape, and dρ(T)/dT and d2ρ(T)/dT2 showed two anomalous features, one near Tan = 30 K and the other near T* = 110 K. The Seebeck coefficient, S(T), also displays peculiar behavior near the Tan and T*. We also report a rather smaller critical current density, Jc = 102 ∼ 104 A/cm2, compared to those observed for the other pnictides and doped chalcogenides.

  14. Leading-order hadronic contribution to the anomalous magnetic moment of the muon from N_f=2+1+1 twisted mass fermions

    CERN Document Server

    Burger, Florian; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B

    2013-01-01

    We present results for the leading order QCD correction to the anomalous magnetic moment of the muon including the first two generations of quarks as dynamical degrees of freedom. Several light quark masses are examined in order to yield a controlled extrapolation to the physical pion mass. We analyse ensembles for three different lattice spacings and several volumes in order to investigate lattice artefacts and finite-size effects, respectively. We also provide preliminary results for this quantity for two flavours of mass-degenerate quarks at the physical value of the pion mass.

  15. Leading-order hadronic contribution to the anomalous magnetic moment of the muon from N{sub f}=2+1+1 twisted mass fermions

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Florian; Hotzel, Grit [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Feng, Xu [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus); Renner, Dru B. [Jefferson Lab, Newport News, VA (United States)

    2013-12-15

    We present results for the leading order QCD correction to the anomalous magnetic moment of the muon including the first two generations of quarks as dynamical degrees of freedom. Several light quark masses are examined in order to yield a controlled extrapolation to the physical pion mass. We analyse ensembles for three different lattice spacings and several volumes in order to investigate lattice artefacts and finite-size effects, respectively. We also provide preliminary results for this quantity for two flavours of mass-degenerate quarks at the physical value of the pion mass.

  16. Leading-order hadronic contribution to the anomalous magnetic moment of the muon from N_f=2+1+1 twisted mass fermions

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Florian [Humboldt U. Berlin; Feng, Xu [KEK; Hotzel, Grit [Humboldt U. Berlin; Jansen, Karl [DESY; Petschlies, Marcus [The Cyprus Institute; Renner, Dru B. [JLAB

    2013-11-01

    We present results for the leading order QCD correction to the anomalous magnetic moment of the muon including the first two generations of quarks as dynamical degrees of freedom. Several light quark masses are examined in order to yield a controlled extrapolation to the physical pion mass. We analyse ensembles for three different lattice spacings and several volumes in order to investigate lattice artefacts and finite-size effects, respectively. We also provide preliminary results for this quantity for two flavours of mass-degenerate quarks at the physical value of the pion mass.

  17. Production of W-+ with an anomalous magnetic moment via the collision of an ultrahigh-energy (anti)neutrino on a target nucleon

    CERN Document Server

    Rosado, A

    2003-01-01

    We discuss the production of W-+ bosons in deep inelastic processes (anti-nu)nu + nucleon --> l+- + W-+ + X, in the context of an electroweak model in which the vector boson self interactions may be different from those prescribed by the electroweak standard model. We present results which show the strong dependence of the cross section on the anomalous magnetic dipole moment kappa of the W+-. We show that even small deviations from the standard model value of kappa (kappa=1) could imply observable deviations in the cross section rates of W-+ production through the collision of an ultrahigh energy (anti)neutrino on a target nucleon.

  18. Subtractive procedure for calculating the anomalous electron magnetic moment in QED and its application for numerical calculation at the three-loop level

    Science.gov (United States)

    Volkov, S. A.

    2016-06-01

    A new subtractive procedure for canceling ultraviolet and infrared divergences in the Feynman integrals described here is developed for calculating QED corrections to the electron anomalous magnetic moment. The procedure formulated in the form of a forest expression with linear operators applied to Feynman amplitudes of UV-diverging subgraphs makes it possible to represent the contribution of each Feynman graph containing only electron and photon propagators in the form of a converging integral with respect to Feynman parameters. The application of the developed method for numerical calculation of two- and threeloop contributions is described.

  19. Mechanochemical synthesis and magnetic properties of maghemite

    Directory of Open Access Journals (Sweden)

    Marin M. Tadić

    2011-07-01

    Full Text Available This work presents the results of an investigation on maghemite (γ -Fe2O3 nanoparticles magnetic properties, which show superparamagnetic behavior i.e. superparamagnetism. Nanoscale maghemite samples were obtained by the mechanochemical method. The crystal structure of the samples was analyzed by the electron diffraction and the X-ray powder diffraction. The formation of monophase maghemite was shown. The particle size was determined by the transmission electron microscopy (TEM. The shift of the blockage temperature TB towards lower values with increasing field strength is significant, which is the indication of the superparamagnetism in the system under consideration.

  20. On-line Texture Analysis for Magnetic Property Control

    OpenAIRE

    Bunge, H. J.; Kopineck, H. J.; Wagner, F

    1989-01-01

    Magnetic properties of hard and soft magnetic materials are strongly anisotropic, i.e. they depend on the crystal direction in which they are being considered. Technological materials are usually polycrystalline. Hence, their properties are orientation mean values of the properties of the crystallites with the texture of the material as the weight function. Inspection and control of magnetic properties of materials thus requires inspection and control of the materials texture which can be car...

  1. Structural, Electronic, Magnetic, and Vibrational Properties of Graphene and Silicene: A First-Principles Perspective

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-11-01

    This thesis covers the structural, electronic, magnetic, and vibrational properties of graphene and silicene. In Chapter I, we will start with an introduction to graphene and silicene. In Chapter II, we will briefly discuss about the methodology (i. e. density functional theory)In Chapter III, we will introduce band gap opening in graphene either by introducing defects/doping or by creating superlattices with h-BN substrate. In Chapter IV, we will focus on the structural and electronic properties of K and Ge-intercalated graphene on SiC(0001). In addition, the enhancement of the superconducting transition temperature in Li-decorated graphene supported by h-BN substrate will be discussed. In Chapter V, we will discuss the vibrational properties of free-standing silicene. In addition, superlattices of silicene with h-BN as well as the phase transition in silicene by applying an external electric field will be discussed. The electronic and magnetic properties transition metal decorated silicene will be discussed, in particular the realization of the quantum anomalous Hall effect will be addressed. Furthermore, the structural, electronic, and magnetic properties of Mn decorated silicene supported by h-BN substrate will be discussed. The conclusion is included in Chapters VI. Finally, we will end with references and a list of publications for this thesis.

  2. Photo- and gas-tuned, reversible thermoelectric properties and anomalous photo-thermoelectric effects of platinum-loaded tungsten trioxide

    Science.gov (United States)

    Suzuki, Kenta; Watanabe, Takuya; Kakemoto, Hirofumi; Irie, Hiroshi

    2016-06-01

    We report the photo- and gas-controllable properties of platinum-loaded tungsten trioxide (Pt/WO3), which is of interest for developing practical applications of WO3 as well as for interpreting such phenomena from scientific viewpoints. Here, a Pt/WO3 thin film generated a thermoelectric power due to the ultraviolet-light-induced band-gap excitation (photochromic (PC) reaction) and/or dark storage in formic acid vapor (gaschromic (GC) reaction) in the absence of O2, resulting from the generation of W5+ ions. After such chromic reactions, the electrical conductivity (σ) is increased, whereas the absolute value of the Seebeck coefficient (S) is decreased. The changes in σ and S and their rate of change for consistency increased in the order of: during the PC reaction extracted from the W5+ state, decreasing the number of W5+ in HxWO3 and thus contributing to the increase in Sphoto. After light irradiation, the accumulated electrons in Pt are returned to the energetically favorable W5+ state, and Pt/HxWO3 are returned to the initial state. Then both σ and S are decreased. The mechanisms of our anomalous, nontrivial photo-thermoelectric effects are presumed to be different from that involving the two-carrier contribution to the transport properties.

  3. Comment on ``Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends'' [J. Chem. Phys. 138, 054903 (2013)

    Science.gov (United States)

    Colmenero, J.

    2013-05-01

    In a recent paper by Ngai and Capaccioli ["Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends," J. Chem. Phys. 138, 054903 (2013), 10.1063/1.4789585] the authors claimed that the so-called coupling model (CM) provides a unified explanation of all dynamical anomalies that have been reported for dynamically asymmetric blends over last ten years. Approximately half of the paper is devoted to chain-dynamic properties involving un-entangled polymers. According to the authors, the application of the CM to these results is based on the existence of a crossover at a time tc ≈ 1-2 ns of the magnitudes describing chain-dynamics. Ngai and Capaccioli claimed that the existence of such a crossover is supported by the neutron scattering and MD-simulation results, corresponding to the blend poly(methyl methacrylate)/poly(ethylene oxide), by Niedzwiedz et al. [Phys. Rev. Lett. 98, 168301 (2007), 10.1103/PhysRevLett.98.168301] and Brodeck et al. [Macromolecules 43, 3036 (2010), 10.1021/ma902820a], respectively. Being one of the authors of these two papers, I will demonstrate here that there is no evidence supporting such a crossover in the data reported in these papers.

  4. Tensile Properties of Pla And Phbv Blends: Anomalous Elongation and Aging

    OpenAIRE

    Gérard, Thibaut; Noto, Tiffany; Budtova, Tatiana

    2012-01-01

    International audience Polylactide (PLA) and polyhydroxyalkanoates (PHA) are polymers made from renewable resources. Despite their growing competitiveness with conventional petrol-based polymers, they still have some disadvantages such as poor (fragile) mechanical properties. Blending is a potentially prospective way of obtaining new materials with improved properties, which can overcome the drawbacks of the pure components. In this work, PLA and poly(hydroxybutyrate-co-hydroxyvalerate) (P...

  5. Nanoscale magnetism and novel electronic properties of a bilayer bismuth(111) film with vacancies and chemical doping.

    Science.gov (United States)

    Sahoo, M P K; Zhang, Yajun; Wang, Jie

    2016-07-27

    Magnetically doped topological insulators (TIs) exhibit several exotic phenomena including the magnetoelectric effect and quantum anomalous Hall effect. However, from an experimental perspective, incorporation of spin moment into 3D TIs is still challenging. Thus, instead of 3D TIs, the 2D form of TIs may open up new opportunities to induce magnetism. Based on first principles calculations, we demonstrate a novel strategy to realize robust magnetism and exotic electronic properties in a 2D TI [bilayer Bi(111) film: abbreviated as Bi(111)]. We examine the magnetic and electronic properties of Bi(111) with defects such as bismuth monovacancies (MVs) and divacancies (DVs), and these defects decorated with 3d transition metals (TMs). It has been observed that the MV in Bi(111) can induce novel half metallicity with a net magnetic moment of 1 μB. The origin of half metallicity and magnetism in MV/Bi(111) is further explained by the passivation of the σ-dangling bonds near the defect site. Furthermore, in spite of the nonmagnetic nature of DVs, the TMs (V, Cr, Mn, and Fe) trapped at the 5/8/5 defect structure of DVs can not only yield a much higher spin moment than those trapped at the MVs but also display intriguing electronic properties such as metallic, semiconducting and spin gapless semiconducting properties. The predicted magnetic and electronic properties of TM/DV/Bi(111) systems are explained through density of states, spin density distribution and Bader charge analysis. PMID:27406933

  6. Nanoscale magnetism and novel electronic properties of a bilayer bismuth(111) film with vacancies and chemical doping.

    Science.gov (United States)

    Sahoo, M P K; Zhang, Yajun; Wang, Jie

    2016-07-27

    Magnetically doped topological insulators (TIs) exhibit several exotic phenomena including the magnetoelectric effect and quantum anomalous Hall effect. However, from an experimental perspective, incorporation of spin moment into 3D TIs is still challenging. Thus, instead of 3D TIs, the 2D form of TIs may open up new opportunities to induce magnetism. Based on first principles calculations, we demonstrate a novel strategy to realize robust magnetism and exotic electronic properties in a 2D TI [bilayer Bi(111) film: abbreviated as Bi(111)]. We examine the magnetic and electronic properties of Bi(111) with defects such as bismuth monovacancies (MVs) and divacancies (DVs), and these defects decorated with 3d transition metals (TMs). It has been observed that the MV in Bi(111) can induce novel half metallicity with a net magnetic moment of 1 μB. The origin of half metallicity and magnetism in MV/Bi(111) is further explained by the passivation of the σ-dangling bonds near the defect site. Furthermore, in spite of the nonmagnetic nature of DVs, the TMs (V, Cr, Mn, and Fe) trapped at the 5/8/5 defect structure of DVs can not only yield a much higher spin moment than those trapped at the MVs but also display intriguing electronic properties such as metallic, semiconducting and spin gapless semiconducting properties. The predicted magnetic and electronic properties of TM/DV/Bi(111) systems are explained through density of states, spin density distribution and Bader charge analysis.

  7. Magnetic properties of MnPt

    Energy Technology Data Exchange (ETDEWEB)

    Severin, C. S.

    1977-06-01

    The magnetic properties of quenched and annealed powder specimens of MnPt were investigated using x-ray diffraction, magnetization measurements and neutron diffraction techniques. Thin films of MnPt were prepared by rf sputtering techniques and the films were investigated by x-ray diffraction and magnetization measurements. The powder specimens of MnPt were found to be typically antiferromagnetic in an L1/sub 0/ structure with Mn atoms occupying the (001) planes. The Mn moments were antiparallel to their nearest neighbors in the (001) planes. The atomic moment of Mn is (4.1 +- .2) ..mu../sub B/ for the annealed specimens and (3.9 +- .2) ..mu../sub B/ for the quenched specimens. Neutron data failed to determine whether or not Pt carries a moment. Assuming a moment associated with the Pt atoms, the maximum value is 0.2 ..mu../sub B/ per atom. The quenched specimens contained small ferromagnetic regions probably with a composition of 18-32 at. percent Mn. The sputtered films of MnPt were highly disordered in all but one specimen, which was amorphous. The films were ferromagnetic with the deduced Mn moment of (3.0 +- .3) ..mu../sub B/ per atom, which may not represent the true value because the films were not entirely ferromagnetic.

  8. 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...

  9. Magnetic Properties of Magnetic Nanoparticles for Efficient Hyperthermia

    OpenAIRE

    Obaidat, Ihab M.; Bashar Issa; Yousef Haik

    2015-01-01

    Localized magnetic hyperthermia using magnetic nanoparticles (MNPs) under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnet...

  10. Magnetic Properties of Ni Nanoparticles and Ni(C) Nanocapsules

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Structure and magnetic properties of Ni nanoparticles and Ni(C) nanocapsules were studied. The carbon atoms hardly affect the lattice of Ni to form Ni-C solid solution or nickel carbides. The large thermal irreversibility in zerofield-cooled and zero-field magnetization curves indicates magnetic blocking with a wide energy barrier. Saturation magnetization, remanent magnetization and coercivity of Ni(C) nanocapsules decrease with increasing temperature.

  11. Fundamental magnetic properties of Greigite (Fe3S4)

    OpenAIRE

    Chang, Liao

    2009-01-01

    Over the last twenty years, greigite (Fe3S4), an authigenic magnetic iron sulphide mineral, has been increasingly identified in sulphate-reducing marine and lacustrine sedimentary systems. Its presence can significantly affect palaeomagnetic and environmental magnetic records. Understanding the recording characteristics of any magnetic mineral requires that its fundamental magnetic properties are known. However, unlike magnetite (Fe3O4) and other common terrestrial magnetic minerals, the fund...

  12. Anomalous electrostatic potential properties in carbon nanotube thin films under a weak external electric field

    OpenAIRE

    Ishiyama, U; Cuong, Nguyen Thanh; Okada, Susumu

    2016-01-01

    Using density functional theory, we studied the electronic properties of carbon nanotube (CNT) thin films under an electric field. The carrier accumulation due to the electric field depends strongly on the CNT species forming the thin films. Under a low electron concentration, the injected electrons are distributed throughout the CNTs, leading to an unusual electric field between CNTs, the direction of which is opposite to that of the applied field. This unusual field response of CNT thin fil...

  13. Anomalous magnetic response of a quasi-periodic mesoscopic ring in presence of Rashba and Dresselhaus spin-orbit interactions

    Science.gov (United States)

    Patra, Moumita; Maiti, Santanu K.

    2016-04-01

    We investigate the properties of persistent charge current driven by magnetic flux in a quasi-periodic mesoscopic Fibonacci ring with Rashba and Dresselhaus spin-orbit interactions. Within a tight-binding framework we work out individual state currents together with net current based on second-quantized approach. A significant enhancement of current is observed in presence of spin-orbit coupling and sometimes it becomes orders of magnitude higher compared to the spin-orbit interaction free Fibonacci ring. We also establish a scaling relation of persistent current with ring size, associated with the Fibonacci generation, from which one can directly estimate current for any arbitrary flux, even in presence of spin-orbit interaction, without doing numerical simulation. The present analysis indeed gives a unique opportunity of determining persistent current and has not been discussed so far.

  14. Magnetic nanoparticles and concentrated magnetic nanofluids: Synthesis, properties and some applications

    Institute of Scientific and Technical Information of China (English)

    Ladislau Vékás; Doina Bica; Mikhail V. Avdeev

    2007-01-01

    This paper reviews some recent results concerning chemical synthesis of magnetic nanoparticles and preparation of various types of magnetic nanofluids. Structural properties and behaviour in external magnetic field of magnetic nanofluids will be emphasized with relation to their use in leakage-free rotating seals and in biomedical applications.

  15. Anomalous properties of heavy fermion materials%重费米子材料中的反常物性

    Institute of Scientific and Technical Information of China (English)

    杨义峰

    2014-01-01

    Heavy fermion research is of great importance for exploring the organization of exotic quantum phenomena in strongly correlated electron systems. Our recent studies on the anom-alous normal state properties of heavy fermion materials reveal a universal temperature evolution governing the emergence of heavy electrons and the presence of the Fano interference effect. Our work provides a new avenue for understanding heavy fermion physics as well as the underlying mechanism of unconventional superconductivity.%重费米子研究对探索强关联电子体系新奇量子现象的组织原则具有重要的意义。文章介绍了作者近年来对重费米子材料正常态反常性质的研究进展,揭示了重电子的普适温度演化行为和Fano干涉效应,为理解重费米子物理和探索非常规超导机理提供了新的思路。

  16. Kagome network compounds and their novel magnetic properties.

    Science.gov (United States)

    Pati, Swapan K; Rao, C N R

    2008-10-21

    Compounds possessing the Kagome network are truly interesting because of their unusual low-energy properties. They exhibit magnetic frustration because of the triangular lattice inherent to the hexagonal bronze structure they possess, as indeed demonstrated by some of the Fe(3+) jarosites, but this is not the general case. Kagome compounds formed by transition metal ions with varying spins exhibit novel magnetic properties, some even showing evidence for magnetic order and absence of frustration. We describe the structure and magnetic properties of this interesting class of materials and attempt to provide an explanation for the variety of properties on the basis of theoretical considerations.

  17. Optimization of the magnetic properties of nanostructured Y-Co-Fe alloys for permanent magnets

    Directory of Open Access Journals (Sweden)

    P. Tozman

    2016-05-01

    Full Text Available The structural and magnetic properties of ball-milled Fe-doped Y Co5−xFex(0 ≤ x ≤ 0.5 were investigated. The magnetization increases with Fe-doping up to the solid solubility limit, x = 0.3 without destroying the crystal structure or degrading the coercivity. A special magnet array is designed using ring magnets for pressing the powders under magnetic field in order to achieve magnetic alignment. A dramatic increase in magnetization is observed for magnetically aligned Y Co4.8Fe0.2 pressed ingots.

  18. Magnetic properties of rare earth iron compounds

    International Nuclear Information System (INIS)

    In this thesis, a study is made of hyperfine interactions in the intermetallic compounds Rsub(x)Fesub(y) (R = rare earth, Y or Th) by using the Moessbauer effect in the 57Fe nucleus. The hyperfine interactions in two series of Rsub(x)Fesub(y) compounds, for which Ysub(x)Fesub(y) and Ersub(x)Fesub(y) were chosen, are studied. Thus a comparison can be made between the magnetic properties of compounds with diamagnetic yttrium and ferromagnetic erbium, respectively. In addition, the magnetic anisotropy of these compounds Ysub(x)Fesub(y) and Ersub(x)Fesub(y) has been investigated. The major part of this thesis concerns a study of the R2Fe17 intermetallic compounds. Since Co or Ni substitution for Fe in R2Fe17 compounds results in a fast increase of the Curie temperature, some pseudobinary R2Fesub(17-x)Msub(x) compounds with R = Tm and Er and M = Co and Ni, have been investigated. ThFe5 has been studied, since it is the only known existing RFe5 compound with a crystal structure which is closely related to that of Th2Fe17

  19. Determination of magnetic properties of multilayer metallic thin films

    CERN Document Server

    Birlikseven, C

    2000-01-01

    and magnetization measurements were taken. In recent year, Giant Magnetoresistance Effect has been attracting an increasingly high interest. High sensitivity magnetic field detectors and high sensitivity read heads of magnetic media can be named as important applications of these films. In this work, magnetic and electrical properties of single layer and thin films were investigated. Multilayer thin films were supplied by Prof. Dr. A. Riza Koeymen from Texas University. Multilayer magnetic thin films are used especially for magnetic reading and magnetic writing. storing of large amount of information into small areas become possible with this technology. Single layer films were prepared using the electron beam evaporation technique. For the exact determination of film thicknesses, a careful calibration of the thicknesses was made. Magnetic properties of the multilayer films were studied using the magnetization, magnetoresistance measurements and ferromagnetic resonance technique. Besides, by fitting the exper...

  20. Negative thermal expansion and associated anomalous physical properties: review of the lattice dynamics theoretical foundation

    Science.gov (United States)

    Dove, Martin T.; Fang, Hong

    2016-06-01

    Negative thermal expansion (NTE) is the phenomenon in which materials shrink rather than expand on heating. Although NTE had been previously observed in a few simple materials at low temperature, it was the realisation in 1996 that some materials have NTE over very wide ranges of temperature that kick-started current interest in this phenomenon. Now, nearly two decades later, a number of families of ceramic NTE materials have been identified. Increasingly quantitative studies focus on the mechanism of NTE, through techniques such as high-pressure diffraction, local structure probes, inelastic neutron scattering and atomistic simulation. In this paper we review our understanding of vibrational mechanisms of NTE for a range of materials. We identify a number of different cases, some of which involve a small number of phonons that can be described as involving rotations of rigid polyhedral groups of atoms, others where there are large bands of phonons involved, and some where the transverse acoustic modes provide the main contribution to NTE. In a few cases the elasticity of NTE materials has been studied under pressure, identifying an elastic softening under pressure. We propose that this property, called pressure-induced softening, is closely linked to NTE, which we can demonstrate using a simple model to describe NTE materials. There has also been recent interest in the role of intrinsic anharmonic interactions on NTE, particularly guided by calculations of the potential energy wells for relevant phonons. We review these effects, and show how anhamonicity affects the response of the properties of NTE materials to pressure.

  1. Numerical calculations of magnetic properties of nanostructures

    CERN Document Server

    Kapitan, Vitalii; Nefedev, Konstantin

    2015-01-01

    Magnetic force microscopy and scanning tunneling microscopy data could be used to test computer numerical models of magnetism. The elaborated numerical model of a face-centered lattice Ising spins is based on pixel distribution in the image of magnetic nanostructures obtained by using scanning microscope. Monte Carlo simulation of the magnetic structure model allowed defining the temperature dependence of magnetization; calculating magnetic hysteresis curves and distribution of magnetization on the surface of submonolayer and monolayer nanofilms of cobalt, depending on the experimental conditions. Our developed package of supercomputer parallel software destined for a numerical simulation of the magnetic-force experiments and allows obtaining the distribution of magnetization in one-dimensional arrays of nanodots and on their basis. There has been determined interpretation of magneto-force microscopy images of magnetic nanodots states. The results of supercomputer simulations and numerical calculations are in...

  2. Efimov effect and anomalous transport properties of a quantum Lorentz gas

    International Nuclear Information System (INIS)

    The Lorentz gas is one of the simplest many-body systems which admits a detailed theoretical analysis still having a meaningful physical interpretation. The author studies a complication for the description of the equilibrium state of a gas due to the so called Efimov effect, being an anomaly of the quantum mechanical three-body system. In statistical mechanical studies concerning the thermodynamic properties of gases it is usually assumed that the constituents interact via short-range potentials, which excludes for instance the Coulomb gas. The author investigates the consequences of the effective long-range behaviour due to the Efimov effect in the three-body sub-systems for a binary gas mixture. In particular problems arise in the cluster expansion of the quantum mechanical partition function where it can readily be shown that the bound-state part of the three-particle contribution diverges logarithmically at the Efimov point. The question is whether this implies the divergence of the complete three particle contribution or not. Some aspects of the non-equilibrium behaviour of the quantum Lorentz gas are studied. (Auth.)

  3. Anomalous dielectric and thermal properties of Ba-doped PbZrO3 ceramics

    Science.gov (United States)

    Pirc, R.; Rožič, B.; Koruza, J.; Cordoyiannis, G.; Malič, B.; Kutnjak, Z.

    2015-11-01

    The dielectric and thermal properties of an antiferroelectric (AFE) material characterised by an intermediate ferroelectric (FE) phase between the AFE and paraelectric phase in zero field are studied by means of a generalised Landau-Kittel model of AFEs. A temperature-dependent coupling of the two sublattices is introduced in accordance with the Rae-Dove (RD) model of re-entrant phase transitions. The sublattice polarisation components are calculated as functions of temperature and the applied electric field by minimising numerically the free energy. The calculated dielectric susceptibility shows anomalies at the boundaries of the intermediate FE phase, characteristic for first-order phase transitions. It is shown that this behaviour is in qualitative agreement with the measured dielectric constant in Ba-doped PbZrO3 ceramics. The model also predicts a negative adiabatic electrocaloric temperature change Δ T in a broad temperature range in the AFE phase, in qualitative agreement with experiments. The dipolar heat capacity is also predicted to be negative in the intermediate phase in zero field, in analogy with the results of the RD model.

  4. A study of the hard magnetic properties in different hard magnetic materials

    International Nuclear Information System (INIS)

    The magnetic properties of several hard magnetic materials have been investigated to determine any trends in their magnetic characteristics. The materials studied were Nd15Fe77B8, SmCo5, Sm2 (Co,Fe,Cu,Zr)17, strontium ferrite magnets and single domain particles of Ba-ferrite and Cu-Mn-Al. The initial magnetization curves, field dependence of coercivity and remanence curves were measured

  5. Structural Origin of the Anomalous Temperature Dependence of the Local Magnetic Moments in the CaFe2As2 Family of Materials

    Science.gov (United States)

    Ortenzi, L.; Gretarsson, H.; Kasahara, S.; Matsuda, Y.; Shibauchi, T.; Finkelstein, K. D.; Wu, W.; Julian, S. R.; Kim, Young-June; Mazin, I. I.; Boeri, L.

    2015-01-01

    We report a combination of Fe K β x-ray emission spectroscopy and density functional reduced Stoner theory calculations to investigate the correlation between structural and magnetic degrees of freedom in CaFe2(As1-xPx) 2 . The puzzling temperature behavior of the local moment found in rare earth-doped CaFe2As2 [H. Gretarsson et al., Phys. Rev. Lett. 110, 047003 (2013)] is also observed in CaFe2(As1-xPx) 2 . We explain this phenomenon based on first-principles calculations with scaled magnetic interaction. One scaling parameter is sufficient to describe quantitatively the magnetic moments in both CaFe2(As1-xPx) 2 (x =0.055 ) and Ca0.78La0.22Fe2As2 at all temperatures. The anomalous growth of the local moments with increasing temperature can be understood from the observed large thermal expansion of the c -axis lattice parameter combined with strong magnetoelastic coupling. These effects originate from the strong tendency to form As-As dimers across the Ca layer in the CaFe2As2 family of materials. Our results emphasize the dual local-itinerant character of magnetism in Fe pnictides.

  6. The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia

    OpenAIRE

    Kappiyoor, Ravi; Liangruksa, Monrudee; Ganguly, Ranjan; Puri, Ishwar K.

    2010-01-01

    Magnetic fluid hyperthermia (MFH) is a noninvasive treatment that destroys cancer cells by heating a ferrofluid-impregnated malignant tissue with an ac magnetic field while causing minimal damage to the surrounding healthy tissue. The strength of the magnetic field must be sufficient to induce hyperthermia but it is also limited by the human ability to safely withstand it. The ferrofluid material used for hyperthermia should be one that is readily produced and is nontoxic while providing suff...

  7. Observation of Anomalous Properties associated with the Low Temperature Structural Distortion in β-FeSe and Related Superconductorsa

    Directory of Open Access Journals (Sweden)

    Wu M. K.

    2012-03-01

    Full Text Available The discovery of Superconductivity in the tetragonal phase FeSe provides a unique platform for the detailed investigation of the correlation between the physical properties and crystal structure to better understand the possible origin of superconductivity in the new iron-based superconductors. We have carried out a series of properties characterizations by measuring magnetic susceptibility, Raman, NMR and femtosecond spectroscopy on single crystals and epitaxial thin films of the FeSe and Te-doped Fe(SeTe samples. Our results show clearly the presence of anomalies in all the characterized properties at the temperature where a structural distortion from tetragonal to orthorhombic (or monoclinic appears for all superconducting samples, but not in the non-superconducting ones. This structural distortion was observed not accompanied by a magnetic ordering as commonly occurs in the parent compounds of FeAs-based superconductors. All the observations suggest that the low temperature structural distortion is essential for the occurrence of superconductivity in the FeSe and related compounds. Details of the experimental results will be presented and discussed.

  8. The magnetic properties of potassium holmium double tungstate

    Science.gov (United States)

    Borowiec, M. T.; Dyakonov, V. P.; Khatsko, E. N.; Zayarnyuk, T.; Zubov, E. E.; Szewczyk, A.; Gutowska, M. U.; Rykova, A. I.; Pietosa, J.; Majchrowski, A.; Michalski, E.; Hoffmann, J.-U.; Prokes, K.; Woźniak, K.; Dobrzycki, Ł.; Barański, M.; Domukhovski, V.; Shtyrkhunova, V.; Żmija, J.; Szymczak, H.

    2011-08-01

    The magnetic investigations of potassium holmium double tungstate KHo(WO4)2 have been performed. The results of measurements of magnetic susceptibility and magnetization as a function of temperature (T from 0.3 K up to 100 K) and magnetic field (up to 1.5 T) are presented. A strong anisotropy of magnetic properties was found. The magnetic measurements data were used to calculate the interaction energy. It was shown that the interactions between nearest neighbors Ho3+ ions have antiferromagnetic character.

  9. Laser-Induced Magnetic Nanostructures with Tunable Topological Properties

    OpenAIRE

    Finazzi, M.; Savoini, M.; Khorsand, A. R.; Tsukamoto, A.; Itoh, A.; L. Duo; Kirilyuk, A.; Rasing, T.H.M.; Ezawa, M.

    2013-01-01

    We report the creation and real-space observation of magnetic structures with well-defined topological properties and a lateral size as low as about 150 nm. They are generated in a thin ferrimagnetic film by ultrashort single optical laser pulses. Thanks to their topological properties, such structures can be classified as Skyrmions of a particular type that does not require an externally applied magnetic field for stabilization. Besides Skyrmions, we are able to generate magnetic features wi...

  10. A Measurement Of The Anomalous Magnetic Moment Of The Positive Muon With A Precision Of 0.7 Parts Per Million

    CERN Document Server

    Gray, F E

    2003-01-01

    The anomalous magnetic moment of the positive muon has been measured to a precision of 0.7 parts per million in an experiment at Brookhaven National Laboratory. The standard model prediction for this quantity can be calculated with a similar uncertainty, although there are currently inconsistent results for one crucial part of this evaluation. Comparison of the theoretical and experimental values tests the standard model and probes for physics beyond it, including supersymmetry, for which a large signal is expected from many models. This thesis describes the principle of the experiment and the status of the theoretical evaluations. It concentrates on the details of an energy-binned method of determining the anomalous precession frequency from the recorded data. The result that is obtained, after combination with previous measurements, is aexp;avgm=11659203 8×10- 10, to be compared with the present standard model predictions aSM;e+e- m =11659168.87.7×10 -10and aSM;tm=11659193.2 6.8&...

  11. Magnetic Properties of Heisenberg Thin Films in an External Field

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; ZHANG Jing

    2004-01-01

    The magnetic properties of Heisenberg ferromagnetic films in an external magnetic field are investigated by means of the variational cumulant expansion (VCE). The magnetization can be in principle calculated analytically as the function of the temperature and the number of atomic layers in the film to an arbitrary order of accuracy in the VCE. We calculate the spontaneous magnetization and coercivity to the third order for spin-1/2 Heisenberg films with simple cubic lattices by using a graphic technique.

  12. Injection-Molded Soft Magnets Prepared from Fe-Based Metallic Glass: Mechanical and Magnetic Properties

    Science.gov (United States)

    Zhong, Tian; Huang, Ran; Huang, Jia; Ouyang, Wei

    2015-10-01

    The injection-molded metallic glass soft magnet is prepared from the powder of melt-spun ribbon of Fe36Co36B20Si4Nb4 glassy alloy and Nylon 6,6 of wt.% from 5 to 20 via the polymer injection molding technology. The product is characterized by the SEM, mechanical, and magnetic test. The results indicate that this type of materials has comparable mechanical properties and morphological feature with the conventional injection-molded NdFeB magnet and exhibits excellent soft magnetic behaviors. The magnetic properties of the injected magnets are compared with the raw metallic glass, solvent-casted resin bonding magnets, and thermal-treated magnets to confirm that the processing temperature of Nylon injection does not affect the magnetism. The injection technology is a practical processing method to be applied on the metallic glass for potential usage.

  13. Magnetic properties of cobalt-carbon nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Denys; Prylutskyy, Yuriy; Matzui, Ludmila; Zakharenko, Mykola [National Shevchenko University, Department of Physics, Volodymyrska Str., 64, Kyiv 01680 (Ukraine); Le Normand, Francois; Derory, Alain [Groupe Surfaces-Interfaces, Institut de Physique et Chimie des Materiaux, 23 rue du Loess, BP 43, 67037 Strasbourg (France)

    2010-04-15

    The paper presents the results of experimental study of the structure and magnetic characteristics of Co-graphite compounds, which were obtained by metal reduction of metal chlorides in graphite intercalated compound (GIC) by C{sub 8}K. The obtained materials were shown to have heterogeneous structure consisting of nanographite matrix in which nanoclusters of Co-GIC are distributed. Magnetic field was applied either along or perpendicularly to the C-axis. It was shown that magnetism of this compound is determined mainly by nanoclusters of Co-GIC for which high anisotropy of magnetic characteristic were observed. ZFC and FC temperature dependences of magnetic susceptibility indicate the formation spin glass state below {proportional_to}20 K. It was also shown that experimental dependences of magnetization contain the contribution due to antiferromagnetic sublattice and magnetization due to uncompensated magnetic moments (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Fractal model of anomalous diffusion.

    Science.gov (United States)

    Gmachowski, Lech

    2015-12-01

    An equation of motion is derived from fractal analysis of the Brownian particle trajectory in which the asymptotic fractal dimension of the trajectory has a required value. The formula makes it possible to calculate the time dependence of the mean square displacement for both short and long periods when the molecule diffuses anomalously. The anomalous diffusion which occurs after long periods is characterized by two variables, the transport coefficient and the anomalous diffusion exponent. An explicit formula is derived for the transport coefficient, which is related to the diffusion constant, as dependent on the Brownian step time, and the anomalous diffusion exponent. The model makes it possible to deduce anomalous diffusion properties from experimental data obtained even for short time periods and to estimate the transport coefficient in systems for which the diffusion behavior has been investigated. The results were confirmed for both sub and super-diffusion.

  15. Magnetic properties of CoO nanoparticles

    NARCIS (Netherlands)

    Flipse, CFJ; Rouwelaar, CB; de Groot, FMF

    1999-01-01

    The magnetic circular X-ray dichroism (MCXD) of CoO nanoparticles was measured at low temperatures and in high magnetic fields. The particles show a superparamagnetic behaviour at room temperature, and a large orbital contribution to the magnetic moment at low temperatures was observed. This enhance

  16. Magnetic structures and properties of vanadium diiodide.

    NARCIS (Netherlands)

    Kuindersma, S. R.; Haas, C.; Sanchez, J. P.; Al, R.

    1979-01-01

    Single-crystal measurements of the magnetic susceptibilities of VI2 show an anomaly at a crit. temp. of ∼14 K. This anomaly can be ascribed to a magnetic phase transition from a 120° structure to a collinear arrangement of the spins with a magnetic unit cell amagn = a√3, bmagn = 2 a and cmagn = 2 c.

  17. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)

    Keivan Esfarjani; Z Chen; Y Kawazoe

    2003-01-01

    Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons of the tube screen the magnetization of the dopants: the coupling to the tube is usually antiferromagnetic (except for Cr).

  18. $W^{+-}$-production in $e^{-}$ p-collisions at CERN LEP/LHC energies with a non-standard $W^{+-}$ anomalous magnetic moment

    CERN Document Server

    Gutiérrez-Rodríguez, A

    2000-01-01

    We discuss the production of charged bosons in deep inelastic e-p- scattering, in the context of an electroweak model, in which the vector boson self interactions may be different from those prescribed by the electroweak standard model. We present results which show the strong dependence of the cross section on the anomalous magnetic dipole moment kappa of the W/sup +or-/. We show that even small deviations from the standard model value of kappa ( kappa =1) implies an observable deviation in the W/sup +or-/-production rates at CERN LEP/LHC energies. We also show that for the analysis of the charged boson production via e/sup -/p collisions at LEP/LHC energies will be very important to include the contribution from heavy boson exchange diagrams to the cross section rates. (25 refs).

  19. Hadron production in e+e- annihilation at BABAR, and implication for the muon anomalous magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Frank C. [Caltech, Pasadena, CA (United States). Physics Dept.

    2015-04-29

    The BABAR collaboration has an extensive program of studying hadronic cross sections in low-energy e+e- collisions, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for illuminating the current 3.6 sigma difference between the predicted and the experimental values. We have published results on a number of processes with two to six hadrons in the final state. We report here the results of recent studies with final states that constitute the main contribution to the hadronic cross section in the energy region between 1 and 3 GeV, as e+e- → K+K-, π+π-, and e+e- → 4 hadrons

  20. The strange and charm quark contributions to the anomalous magnetic moment (g -2) of the muon from current-current correlators

    CERN Document Server

    Chakraborty, Bipasha; Donald, Gordon; Dowdall, Rachel; de Oliveira, Pedro Gonçalves; Koponen, Jonna; Lepage, G Peter; Teubner, T

    2014-01-01

    We describe a new technique (presented in arXiv:1403.1778) to determine the contribution to the anomalous magnetic moment (g-2) of the muon coming from the hadronic vacuum polarisation using lattice QCD. Our method uses Pad\\'{e} approximants to reconstruct the Adler function from its derivatives at $q^2=0$. These are obtained simply and accurately from time-moments of the vector current-current correlator at zero spatial momentum. We test the method using strange quark correlators calculated on MILC Collaboration's $n_f$ = 2+1+1 HISQ ensembles at multiple values of the lattice spacing, multiple volumes and multiple light sea quark masses (including physical pion mass configurations).

  1. Control over magnetic properties in bulk hybrid materials

    Science.gov (United States)

    Urban, Christian; Quesada, Adrian; Saerbeck, Thomas; Rubia, Miguel Angel De La; Garcia, Miguel Angel; Fernandez, Jose Francisco; Schuller, Ivan K.; UCSD Collaboration; Instituto de Ceramica, Madrid Collaboration; Institut Laue-Langevin, Grenoble Collaboration

    We present control of coercivity and remanent magnetization of a bulk ferromagnetic material embedded in bulk vanadium sesquioxide (V2O3) by using a standard bulk synthesis procedure. The method generalizes the use of structural phase transitions of one material to control structural and magnetic properties of another. A structural phase transition (SPT) in the V2O3 host material causes magnetic properties of Ni to change as function of temperature. The remanent magnetization and the coercivity are reversibly controlled by the SPT without additional external magnetic fields. The reversible tuning shown here opens the pathway for controlling the properties of a vast variety of magnetic hybrid bulk systems. This Work is supported by the Office of Basic Energy Science, U.S. Department of Energy, BES-DMS funded by the Department of Energy's Office of Basic Energy Science, DMR under grant DE FG02 87ER-45332.

  2. Magnetic properties of ball-milled TbFe2 and TbFe2B

    Indian Academy of Sciences (India)

    J Arout Chelvane; S Kasiviswanathan; M V Rao; G Markandeyulu

    2004-04-01

    The magnetic properties of ball-milled TbFe2 and TbFe2B were studied by magnetization measurements. X-ray diffraction studies on TbFe2B showed that boron occupied interstitial position in the crystal structure, just as hydrogen did. The value of the saturation magnetization of TbFe2B was found to be smaller than that of TbFe2. This is explained on the basis of a charge transfer between the boron atoms and the 3d band of Fe. The anisotropy of TbFe2B was found to be large compared to that of TbFe2. X-ray diffractograms for the ball milled samples showed that after 80 h of milling, a predominantly amorphous phase was obtained. TbFe2B was found to undergo easy amorphization compared to TbFe2. Magnetization of TbFe2 was found to decrease rapidly with initial milling hours and was found to be constant with further hours of milling. TbFe2B exhibited an anomalous behaviour with an increase in moment with milling hours and this may be due to the segregation of -Fe.

  3. Spectral properties of superconductors with ferromagnetically ordered magnetic impurities

    Science.gov (United States)

    Persson, Daniel; Shevtsov, Oleksii; Löfwander, Tomas; Fogelström, Mikael

    2015-12-01

    We present a comprehensive theoretical study of thermodynamic properties of superconductors with a dilute concentration of magnetic impurities, with focus on how the properties of the superconducting host change if the magnetic moments of the impurities order ferromagnetically. Scattering off the magnetic impurities leads to the formation of a band of Yu-Shiba-Rusinov states within the superconducting energy gap that drastically influences superconductivity. In the magnetically ordered system, the magnetization displays a sudden drop as a function of the impurity density or magnetic moment amplitude. The drop occurs as the spin-polarized impurity band crosses the Fermi level and is associated with a quantum phase transition first put forward by Sakurai for the single impurity case. Taking into account that the background magnetic field created by the ordered impurity moments enters as a Zeeman shift, we find that the superconducting phase transition changes from second order to first order for high enough impurity concentrations.

  4. Magnetic and Magneto-Optical Properties in Paramagnetic NdF3 Under High Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; LIU Gong-Qiang

    2005-01-01

    In this paper, we first theoretically report the magnetic and magneto-optical properties in paramagnetic media under high external magnetic field. Considering the action of the external magnetic field He and indirect exchange interaction Hv, the characteristic of the magnetic saturation and the property of the Faraday rotation to be nonlinear with external magnetic field are presented in paramagnetic NdF3. In terms of our theory, the indirect exchange interaction plays an important role in the magnetization M and the Faraday rotation θ in NdF3 under high external magnetic field. The theory is in good agreement with experimental results. On the other hand, a reasonable explanation for the temperature dependence of the ratio of the Verdet constant to the magnetic susceptibility V/x is obtained.

  5. Anomalous magnetic ordering in DyxPr1-x alloys

    DEFF Research Database (Denmark)

    Clegg, P.S.; Cowley, R.A.; Goff, J.P.;

    2000-01-01

    Epitaxial thin-films of DyxPr1-x alloys have been studied using neutron diffraction and magnetization measurements. The crystal structure changes from HCP to Sm type to DHCP as x decreases; each crystal phase has different magnetic behaviour. Surprisingly, long-range order is suppressed in the DHCP...

  6. Theory of the electronic and magnetic structure and transport properties of single molecule magnets

    OpenAIRE

    Rostamzadeh Renani, Fatemeh

    2013-01-01

    Developing electronic components at the molecular scale is the ultimate goal in molecular electronics. Because of their large magnetic anisotropy barriers and associated stable magnetic moments, single molecule magnets (SMMs) bring a new dimension to this field and also raise the possibility of molecular magnetic information storage and quantum computation. Therefore the transport properties of transistors based on individual SMMs are attracting considerable experimental and theoretical inter...

  7. Magnetic and magnetothermal properties and the magnetic phase diagram of high purity single crystalline terbium along the easy magnetization direction.

    Science.gov (United States)

    Zverev, V I; Tishin, A M; Chernyshov, A S; Mudryk, Ya; Gschneidner, K A; Pecharsky, V K

    2014-02-12

    The magnetic and magnetothermal properties of a high purity terbium single crystal have been re-investigated from 1.5 to 350 K in magnetic fields ranging from 0 to 75 kOe using magnetization, ac magnetic susceptibility and heat capacity measurements. The magnetic phase diagram has been refined by establishing a region of the fan-like phase broader than reported in the past, by locating a tricritical point at 226 K, and by a more accurate definition of the critical fields and temperatures associated with the magnetic phases observed in Tb.

  8. Magnetic Properties of Nd12Co6Pb Compound

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The magnetic and magnetocaloric properties for the Nd12Co6Pb compound were investigated. The Curie temperature TC of the magnetic transition of Nd12Co6Pb compound is 194 K. The experimentally determined magnetic effective paramagnetic moment is μeff=12.36 μB per formula unit (3.49 μB per Nd atom). The maximum magnetic entropy change in the low magnetic field changes of 0~2 T for the Nd12Co6Pb compound is about 215.0 J·mole-1·K-1.

  9. Enhancement in magnetic properties of magnesium substituted bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jianlong; Xie, Dan, E-mail: xiedan@mail.tsinghua.edu.cn, E-mail: RenTL@mail.tsinghua.edu.cn; Teng, Changjiu; Zhang, Xiaowen; Zhang, Cheng; Sun, Yilin; Ren, Tian-Ling, E-mail: xiedan@mail.tsinghua.edu.cn, E-mail: RenTL@mail.tsinghua.edu.cn [Institute of Microelectronics, Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084 (China); Zeng, Min; Gao, Xingsen [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510006 (China); Zhao, Yonggang [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)

    2015-06-14

    We report a potential way to effectively improve the magnetic properties of BiFeO{sub 3} (BFO) nanoparticles through Mg{sup 2+} ion substitution at the Fe-sites of BFO lattice. The high purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and Raman spectra. Enhanced magnetic properties are observed in Mg substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. A physical model is proposed to support the observed ferromagnetism of Mg doped samples, and the superparamagnetic properties are revealed by the temperature dependent magnetization measurements. The improved magnetic properties and soft nature obtained by Mg doping in BFO nanoparticles demonstrate the possibility of BFO nanoparticles to practical applications.

  10. Magnetoresistive properties of nanostructured magnetic metals, manganites, and magnetic semiconductors

    Science.gov (United States)

    Solin, N. I.; Romashev, L. N.; Naumov, S. V.; Saranin, A. A.; Zotov, A. V.; Olyanich, D. A.; Kotlyar, V. G.; Utas, O. A.

    2016-02-01

    We consider methods for controlling magnetoresistive parameters of magnetic metal superlattices, manganites, and magnetic semiconductors. By reducing the thickness of ferromagnetic layers in superlattices (e.g., Fe layers in Fe/Cr superlattices), it is possible to form superparamagnetic clustered-layered nanostructures with a magnetoresistance weakly depending on the direction of the external magnetic field, which is very important for applications of such type of materials. Producing Mn vacancies and additionally annealing lanthanum manganites in the oxygen atmosphere, it is possible to increase their magnetoresistance by more than four orders of magnitude. By changing the thickness of p- n junction in the structure of ferromagnetic semiconductors, their magnetoresistance can be increased by 2-3 orders of magnitude.

  11. Synthesis and magnetic properties of Co-Zn magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Vaidyanathan, G. [Department of Physics, Pondicherry Engineering College, Pondicherry 605014 (India)], E-mail: gvn_pec@yahoo.com; Sendhilnathan, S. [Department of Physics, Sri Manakula Vinayagar Engineering College, Pondicherry 605107 (India)], E-mail: sendhil29@yahoo.co.in

    2008-03-15

    Co{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (with x varying from 0 to 0.7) nanoparticles to be used for ferrofluid preparation were prepared by chemical co-precipitation method. The fine particles were suitably dispersed in transformer oil using oleic acid as the surfactant. The magnetization (M{sub s}) and the size of the particles were measured at room temperature. The magnetization (M{sub s}) was found to decrease with the increase in zinc substitution. The magnetic particle size (D{sub m}) of the fluid was found to vary from 11.19 to 4.25 nm decreasing with the increase in zinc substitution.

  12. High temperature permeameter for measuring magnetic properties

    Science.gov (United States)

    Barranger, J. P.

    1972-01-01

    Instrument for measuring magnetic permeability of materials undergoing heat treatment as method for monitoring stress relief and tempering is described. Procedure is based on magnetic potentiometer principle with yoke compensating coils to cancel effects of reluctance of yoke and joint gaps. Instrument is heated with specimen being heat treated.

  13. Stress dependent vector magnetic properties in electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Ktena, Aphrodite, E-mail: aktena@teihal.gr [Department of Electrical Engineering, TEI of Chalkida, Psachna, Evia 34400 (Greece); Davino, Daniele; Visone, Ciro [Engineering Department, University of Sannio (Italy); Hristoforou, Evangelos [Laboratory of Metallurgy, National Technical University of Athens (Greece)

    2014-02-15

    The dependence of macroscopic magnetic properties on applied and residual stresses is promising for development of new magnetic non-destructive evaluation techniques in ferrous materials. The reliability of AC magnetometry, in determining the effect of strain on magnetic macroscopic parameters, is evaluated against scalar and vector Vibrating Sample Magnetometer measurements on strained electrical steel samples after unloading. Hysteresis loops have been measured at 0°, 30°, 45°, 60° and 90° to the direction of the applied stress. Vector magnetic properties reveal a stress-related anisotropy component, which increases with strain and deteriorates after fracture. The effect of residual stress on the saturation and remanent magnetization, as well as the differential susceptibility, is discussed with respect to data from AC magnetometry at 0.1 Hz. The results of the latter are representative of the magnetic configuration of the material under test and make it a promising candidate for NDE applications in steels.

  14. Stress dependent vector magnetic properties in electrical steel

    International Nuclear Information System (INIS)

    The dependence of macroscopic magnetic properties on applied and residual stresses is promising for development of new magnetic non-destructive evaluation techniques in ferrous materials. The reliability of AC magnetometry, in determining the effect of strain on magnetic macroscopic parameters, is evaluated against scalar and vector Vibrating Sample Magnetometer measurements on strained electrical steel samples after unloading. Hysteresis loops have been measured at 0°, 30°, 45°, 60° and 90° to the direction of the applied stress. Vector magnetic properties reveal a stress-related anisotropy component, which increases with strain and deteriorates after fracture. The effect of residual stress on the saturation and remanent magnetization, as well as the differential susceptibility, is discussed with respect to data from AC magnetometry at 0.1 Hz. The results of the latter are representative of the magnetic configuration of the material under test and make it a promising candidate for NDE applications in steels

  15. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt;

    1997-01-01

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

  16. Magnetic properties of a spin-3 Chromium condensate

    OpenAIRE

    He, Liang; Yi, Su

    2009-01-01

    We study the ground state properties of a spin-3 Cr condensate subject to an external magnetic field by numerically solving the Gross-Piteavskii equations. We show that the widely adopted single-mode approximation is invalid under a finite magnetic field. In particular, a phase separation like behavior may be induced by the magnetic field. We also point out the possible origin of the phase separation phenomenon.

  17. Processing, properties and some novel applications of magnetic nanoparticles

    Indian Academy of Sciences (India)

    D Bahadur; J Giri; Bibhuti B Nayak; T Sriharsha; P Pradhan; N K Prasad; K C Barick; R D Ambashta

    2005-10-01

    Magnetic nanoparticles have been prepared by various soft chemical methods including self-assembly. The bare or surface-modified particles find applications in areas such as hyperthermia treatment of cancer and magnetic field-assisted radioactive chemical separation. We present here some of the salient features of processing of nanostructured magnetic materials of different sizes and shapes, their properties and some possible applications. The materials studied included metals, metal-ceramic composites, and ferrites.

  18. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals

    Science.gov (United States)

    Wang, Xiang; Pu, Shengli; Ji, Hongzhu; Yu, Guojun

    2012-05-01

    Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δ n) and figure of merit of optical properties ( Q = Δ n/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of Q R exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field.

  19. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals.

    Science.gov (United States)

    Wang, Xiang; Pu, Shengli; Ji, Hongzhu; Yu, Guojun

    2012-01-01

    Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field. PMID:22587542

  20. Elastic properties of DNA linked flexible magnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Erglis, K; Cebers, A [Department of Theoretical Physics, University of Latvia, Zellu 8, Riga, LV-1002 (Latvia); Zhulenkovs, D; Sharipo, A [Latvian Biomedical Research and Study Center, Ratsupites 1, Riga, LV-1067 (Latvia)], E-mail: aceb@tesla.sal.lv

    2008-05-21

    Elastic properties of magnetic filaments linked by DNA in solutions of univalent and bivalent salts with different pH values are investigated through their deformation in an external field. A strong dependence of the bending modulus in bivalent salt solution on the pH is shown. Experimental results are interpreted on the basis of the magnetic elastica.

  1. Magnetic properties and spin kinetics in Kondo lattices

    Directory of Open Access Journals (Sweden)

    S.I. Belov, A.S. Kutuzov

    2015-12-01

    Full Text Available We present a theoretical model to describe unusual properties of Kondo lattices. The influence of the Kondo effect on the static magnetic susceptibility and electron spin resonance (ESR parameters is studied in a simple molecular field approximation together with a scaling perturbative approach. Theoretical expressions well agree with the ESR and static magnetic susceptibility experimental data.

  2. Magnetic properties of Fe1-xMnx/Fe nanocomposites

    DEFF Research Database (Denmark)

    Anhøj, Thomas Aarøe; Jacobsen, Claus Schelde; Mørup, Steen

    2004-01-01

    We have prepared nanocomposites of mixtures of ferromagnetic alpha-Fe and antiferromagnetic gamma-Fe50Mn50 nanoparticles, and studied their magnetic and structural properties by magnetization measurements, Mössbauer spectroscopy, and x-ray diffraction. A sample consisting of a 1:1 mixture...

  3. Electronic and magnetic properties of Am and Cm

    Energy Technology Data Exchange (ETDEWEB)

    Edelstein, N.

    1985-02-01

    A review of the present status of the analyses of the optical spectra of Am and Cm in various oxidation states is given. From these analyses, the magnetic properties of the ground states of these ions can be determined. These predicted values are compared with the various magnetic measurements available.

  4. Microstructure characterization and magnetic properties of nano structured materials

    International Nuclear Information System (INIS)

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe78Si9B13 ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy (Eds.); selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  5. Microstructure characterization and magnetic properties of nano structured materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.C

    2000-07-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe{sub 78}Si{sub 9}B{sub 13} ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy [eds.]; selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  6. Colossal anisotropy of the magnetic properties of doped lithium nitrodometalates

    Energy Technology Data Exchange (ETDEWEB)

    Antropov, Vladimir P [Ames Laboratory; Antonov, Victor N [Ames Laboratory

    2014-09-01

    We present a first-principles investigation of the electronic structure and physical properties of doped lithium nitridometalates Li2(Li1-xMx)N (LiMN) with M = Cr, Mn, Fe, Co, and Ni. The diverse properties include the equilibrium magnetic moments, magneto-crystalline anisotropy, magneto-optical Kerr spectra, and x-ray magnetic circular dichroism. We explain the colossal magnetic anisotropy in LiFeN by its unique electronic structure which ultimately leads to a series of unusual physical properties. The most unique property is a complete suppression of relativistic effects and freezing of orbital moments for in-plane orientation of the magnetization. This leads to the colossal spatial anisotropy of many magnetic properties including energy, Kerr, and dichroism effects. LiFeN is identified as an ultimate single-ion anisotropy system where a nearly insulating state can be produced by a spin orbital coupling alone. A very nontrivial strongly fluctuating and sign changing character of the magnetic anisotropy with electronic 3d-atomic doping is predicted theoretically. A large and highly anisotropic Kerr effect due to the interband transitions between atomic-like Fe 3d bands is found for LiFeN. A giant anisotropy of the x-ray magnetic circular dichroism for the Fe K spectrum and a very weak one for the Fe L2,3 spectra in LiFeN are also predicted.

  7. Anomalous superfluid density in quantum critical superconductors

    Science.gov (United States)

    Hashimoto, Kenichiro; Mizukami, Yuta; Katsumata, Ryo; Shishido, Hiroaki; Yamashita, Minoru; Ikeda, Hiroaki; Matsuda, Yuji; Schlueter, John A.; Fletcher, Jonathan D.; Carrington, Antony; Gnida, Daniel; Kaczorowski, Dariusz; Shibauchi, Takasada

    2013-01-01

    When a second-order magnetic phase transition is tuned to zero temperature by a nonthermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these “quantum critical” superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature Tc often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below Tc is less well established. Here we report measurements of the magnetic penetration depth in heavy-fermion, iron-pnictide, and organic superconductors located close to antiferromagnetic quantum critical points, showing that the superfluid density in these nodal superconductors universally exhibits, unlike the expected T-linear dependence, an anomalous 3/2 power-law temperature dependence over a wide temperature range. We propose that this noninteger power law can be explained if a strong renormalization of effective Fermi velocity due to quantum fluctuations occurs only for momenta k close to the nodes in the superconducting energy gap Δ(k). We suggest that such “nodal criticality” may have an impact on low-energy properties of quantum critical superconductors. PMID:23404698

  8. Large batch recycling of waste Nd–Fe–B magnets to manufacture sintered magnets with improved magnetic properties

    International Nuclear Information System (INIS)

    The waste Nd–Fe–B sintered magnets up to 500 kg per batch were recycled to manufacture anisotropic sintered magnets by combination of hydrogen decrepitation (HD) and alloying technique. Magnetic properties and thermal stability of both the waste magnets and recycled magnets were investigated. The recycled magnet exhibits magnetic properties with remanence (Br) of 12.38 kGs, coercivity (Hci) of 24.89 kOe, and maximum energy product [(BH)max] of 36.51 MGOe, respectively, which restores 99.20% of Br, 105.65% of Hci, and 98.65% of (BH)max of the waste magnets, respectively. The volume fraction of Nd-rich phase in the recycled magnets is about 10.1 vol.%, which is bigger than that of the waste magnets due to the additive of Nd3PrFe14B alloy containing more rare earth. The remanence temperature coefficient (α) and coercivity temperature coefficient (β) of the recycled magnets are −0.1155%/K and −0.5099%/K in the range of 288–423 K, respectively, which are comparative to those of the waste magnets. - Highlights: • Large batch recycling of waste Nd–Fe–B sintered magnets were performed. • The recycled magnet restores 99.20% of Br, 105.65% of Hci and 98.65% of (BH)max of the magnet. • The recycled magnets bears bigger volume fraction and better distribution of Nd-rich phase. • The recycled magnets exhibit similar temperature coefficients and maximum working temperature

  9. Large batch recycling of waste Nd–Fe–B magnets to manufacture sintered magnets with improved magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.T. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yue, M., E-mail: yueming@bjut.edu.cn [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, W.Q. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Li, X.L.; Yi, X.F.; Huang, X.L. [Anhui Province Key Laboratories of Rare Earth Permanent Magnet Materials, Anhui, 231500 (China); Anhui Earth-panda Advance Magnetic Material Co., Ltd., Anhui, 231500 (China); Zhang, D.T. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Chen, J.W. [Anhui Province Key Laboratories of Rare Earth Permanent Magnet Materials, Anhui, 231500 (China); Anhui Earth-panda Advance Magnetic Material Co., Ltd., Anhui, 231500 (China)

    2015-11-15

    The waste Nd–Fe–B sintered magnets up to 500 kg per batch were recycled to manufacture anisotropic sintered magnets by combination of hydrogen decrepitation (HD) and alloying technique. Magnetic properties and thermal stability of both the waste magnets and recycled magnets were investigated. The recycled magnet exhibits magnetic properties with remanence (B{sub r}) of 12.38 kGs, coercivity (H{sub ci}) of 24.89 kOe, and maximum energy product [(BH){sub max}] of 36.51 MGOe, respectively, which restores 99.20% of B{sub r}, 105.65% of H{sub ci}, and 98.65% of (BH){sub max} of the waste magnets, respectively. The volume fraction of Nd-rich phase in the recycled magnets is about 10.1 vol.%, which is bigger than that of the waste magnets due to the additive of Nd{sub 3}PrFe{sub 14}B alloy containing more rare earth. The remanence temperature coefficient (α) and coercivity temperature coefficient (β) of the recycled magnets are −0.1155%/K and −0.5099%/K in the range of 288–423 K, respectively, which are comparative to those of the waste magnets. - Highlights: • Large batch recycling of waste Nd–Fe–B sintered magnets were performed. • The recycled magnet restores 99.20% of B{sub r}, 105.65% of H{sub ci} and 98.65% of (BH){sub max} of the magnet. • The recycled magnets bears bigger volume fraction and better distribution of Nd-rich phase. • The recycled magnets exhibit similar temperature coefficients and maximum working temperature.

  10. Magnetic properties of the magnetic hybrid membranes based on various polymer matrices and inorganic fillers

    Energy Technology Data Exchange (ETDEWEB)

    Rybak, Aleksandra, E-mail: Aleksandra.Rybak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Kaszuwara, Waldemar [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warszawa (Poland)

    2015-11-05

    Magnetic hybrid membranes based on ethylcellulose (EC), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and various magnetic praseodymium and neodymium powder microparticles as fillers were obtained. Permeability, diffusion and sorption coefficients of O{sub 2}, N{sub 2} and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on constant pressure permeation technique. The microstructure studies and the phase analysis of magnetic membranes were also performed using SEM and XRD. The influence of magnetic parameters, like coercivity, remanence and saturation magnetization of created membranes on the gas transport properties was studied. The results showed that their coercivity depended on composition and microstructure of the magnetic powder. On the other hand, remanence and saturation magnetization increased with the increase of the powder addition in the membrane. It was found that the magnetic membrane's gas transport properties were improved with the increase of membrane's remanence, saturation magnetization and magnetic particle filling. The decrease in powder particle size and associated increase of the membrane's coercivity also positively influenced the gas transport and separation properties of investigated membranes. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes had higher gas permeability, while their permselectivity and solubility coefficient values were rather maintained or slightly increased. The results also showed that the magnetic powder content enhanced significantly gas diffusivity in EC and PPO membranes. It was also analyzed the dependence of the drift coefficient w on the magnetic parameters of investigated membranes. The correlation between the membrane selectivity, permeability and magnetic properties with their XRD characteristics was stated. - Highlights: • Membrane's production consisting of EC or PPO

  11. Magnetic properties of the magnetic hybrid membranes based on various polymer matrices and inorganic fillers

    International Nuclear Information System (INIS)

    Magnetic hybrid membranes based on ethylcellulose (EC), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and various magnetic praseodymium and neodymium powder microparticles as fillers were obtained. Permeability, diffusion and sorption coefficients of O2, N2 and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on constant pressure permeation technique. The microstructure studies and the phase analysis of magnetic membranes were also performed using SEM and XRD. The influence of magnetic parameters, like coercivity, remanence and saturation magnetization of created membranes on the gas transport properties was studied. The results showed that their coercivity depended on composition and microstructure of the magnetic powder. On the other hand, remanence and saturation magnetization increased with the increase of the powder addition in the membrane. It was found that the magnetic membrane's gas transport properties were improved with the increase of membrane's remanence, saturation magnetization and magnetic particle filling. The decrease in powder particle size and associated increase of the membrane's coercivity also positively influenced the gas transport and separation properties of investigated membranes. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes had higher gas permeability, while their permselectivity and solubility coefficient values were rather maintained or slightly increased. The results also showed that the magnetic powder content enhanced significantly gas diffusivity in EC and PPO membranes. It was also analyzed the dependence of the drift coefficient w on the magnetic parameters of investigated membranes. The correlation between the membrane selectivity, permeability and magnetic properties with their XRD characteristics was stated. - Highlights: • Membrane's production consisting of EC or PPO polymers and

  12. Size dependent magnetic properties of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Jhunu; Haik, Yousef. E-mail: haik@eng.fsu.edu; Chen, C.-J.Ching-Jen

    2003-02-01

    {gamma}Fe{sub 2}O{sub 3} nanoparticles has been synthesized by a combination of chemical and ultrasonication procedure and further stabilized with surfactant. Their magnetic properties are compared with the different fractions (10-12, 20-30, 100-150 nm) of commercially available iron oxide. The sizes obtained from the scanning transmission electron micrographs are correlated with the magnetic properties of the particles.

  13. Properties of Magnetized Quark-Hybrid Stars

    CERN Document Server

    Orsaria, M; Vucetich, H; Weber, F

    2011-01-01

    The structure of a magnetized quark-hybrid stars (QHS) is modeled using a standard relativistic mean-field equation of state (EoS) for the description of hadronic matter. For quark matter we consider a bag model EoS which is modified perturbatively to account for the presence of a uniform magnetic field. The mass-radius (M-R) relationship, gravitational redshift and rotational Kepler periods of such stars are compared with those of standard neutron stars (NS).

  14. Magnetic-Coupling Properties in Polycrystals

    OpenAIRE

    Fuentes, L. (Lidia)

    1998-01-01

    Quantitative Texture Analysis procedures for characterisation of polycrystal pyromagnetic, magnetoelectric and piezomagnetic effects are proposed. The considered phenomena link the thermic, electric and elastic subsystems of a given body with its magnetic subsystem. Brief resumes of required thermodynamic, tensor and texture methods are given. Peculiar behaviour of magnetic (axial-tensor) quantities under colour symmetry operations is described. The use of Neumann's Principle in the investiga...

  15. Magnetic properties of FeSe superconductor

    OpenAIRE

    Grechnev, G. E.; Panfilov, A.S.; Desnenko, V. A.; Fedorchenko, A. V.; Gnatchenko, S. L.; Chareev, D. A.; Volkova, O. S.; A.N. Vasiliev

    2012-01-01

    A detailed magnetization study for the novel FeSe superconductor is carried out to investigate the behavior of the intrinsic magnetic susceptibility $\\chi$ in the normal state with temperature and under hydrostatic pressure. The temperature dependencies of $\\chi$ and its anisotropy $\\Delta \\chi=\\chi_{|}-\\chi_{\\bot}$ are measured for FeSe single crystals in the temperature range 4.2-300 K, and a substantial growth of susceptibility with temperature is revealed. The observed anisotropy $\\Delta ...

  16. Neutron diffraction study of anomalous high-field magnetic phases in TmNi2B2C

    DEFF Research Database (Denmark)

    Toft, K.N.; Abrahamsen, A.B.; Eskildsen, M.R.;

    2004-01-01

    .90Yb0.10)Ni2B2C the Q(F)-->Q(AI) phase transition is also observed but at a larger transition field compared to the undoped compound. In (Tm0.85Yb0.15)Ni2B2C the Q(F) phase persists up to at least 1.8 T. The magnetic correlation length of the Q(AI) phase in TmNi2B2C measured parallel and perpendicular......We present a (B,T)-phase diagram of the magnetic superconductor TmNi2B2C obtained by neutron scattering. The measurements were performed in magnetic fields up to 6 T applied along the crystalline a axis. The observed phases are characterized by three ordering vectors, Q(F)=(0.094,0.094,0),Q(AI)=(0.......483,0,0), and Q(AII)=(0.496,0,0), all with the magnetic moment along the c axis. In zero and low fields the Tm 4f-moments order in a long wavelength transverse spin density wave with Q=Q(F). The magnetic Q(AI) structure is stabilized by an applied field of 1 T and a transition to Q(AII) is observed at 4 T...

  17. MAGNETIC PROPERTY CHANGE IN AN AUSTENITIC STAINLESS STEEL SUBJECTED TO DAMAGE AT ELEVATED TEMPERATURE - MICROSTRUCTURE RESPONSIBLE FOR MAGNETIC PROPERTY

    Institute of Scientific and Technical Information of China (English)

    Y.Nagae; K.Aoto

    2004-01-01

    It has been found that magnetic property changes in austenitic stainless steel subjected to creep at high temperature. The change of magnetic property is mainly due to decrease the chromium concentration in the vicinity of grain boundary and transform into martensite in the area. However this result is for short-term creep. It is necessary to evaluate the long-term creep in order to develop non-destructive technique for plants. Moreover it is important to evaluate the fatigue. The change of magnetic property for those damages at high temperatures is investigated. The transformation into martensite is observed for both the long-term creep and fatigue. The magnetic regions are observed in sever deformed area and near crack. Then the formation of magnetic phases is related to the damage. The damage at high temperature can be universally evaluated.

  18. Neutrino Mass, Dark Matter and Anomalous Magnetic Moment of Muon in a $U(1)_{L_{\\mu}-L_{\\tau}}$ Model

    CERN Document Server

    Biswas, Anirban; Khan, Sarif

    2016-01-01

    The observation of neutrino masses, mixing and the existence of dark matter are amongst the most important signatures of physics beyond the Standard Model (SM). In this paper, we propose to extend the SM by a local $L_\\mu - L_\\tau$ gauge symmetry, two additional complex scalars and three right-handed neutrinos. The $L_\\mu - L_\\tau$ gauge symmetry is broken spontaneously when one of the scalars acquires a vacuum expectation value. The $L_\\mu - L_\\tau$ gauge symmetry is known to be anomaly free and can explain the beyond SM measurement of the anomalous muon $({\\rm g-2})$ through additional contribution arising from the extra $Z_{\\mu\\tau}$ mediated diagram. Small neutrino masses are explained naturally through the Type-I seesaw mechanism, while the mixing angles are predicted to be in their observed ranges due to the broken $L_\\mu-L_\\tau$ symmetry. The second complex scalar is shown to be stable and becomes the dark matter candidate in our model. We show that while the $Z_{\\mu\\tau}$ portal is ineffective for the...

  19. Electrical Properties of Nanostructured Magnetic Colloid and Influence of Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    PU Sheng-Li; CHEN Xian-Feng; DI Zi-Yun; GENG Tao; XIA Yu-Xing

    2007-01-01

    We investigate the electrical properties of the nanostructured magnetic colloid without and with magnetic Held. The competition between the directional motion of the charged magnetic nanoparticles and other minor nonmagnetic impurities (also small amount of ions) under applied voltage and their random orientation due to thermal activation is implemented to elaborate the electrically conduction mechanism under zero magnetic Geld. Two equivalent electric circuits are employed for explaining the charging and discharging processes. The tunnelling conduction mechanism upon application of externally magnetic field may exist in the nanostructured magnetic colloid. The alternation of the two conduction mechanisms accounts for the current spikes when the magnetic field is switched on or off. This work presents the peculiar electrical phenomena of the magnetically colloidal system.

  20. Magnetic properties and magnetic exchange interactions in Gd1-xREx(RE=Pr, Nd) alloys

    Institute of Scientific and Technical Information of China (English)

    肖素芬; 陈云贵

    2016-01-01

    The effect of Pr, Nd addition on the magnetic properties and magnetic exchange interaction of gadolinium alloys was sys-tematically studied. Curie temperatureTC and magnetic moment of Gd1–xREx (RE=Pr, Nd) systems withx<0.05 were investigated. Whenx<0.05, Pr and Nd formed respectively with Gd continuous solid solution which has the crystalline structure HCP. Study on the magnetic behavior indicated that at near room temperature, the simple ferromagnetism prevailed in these two systems of alloy. The Curie temperature and magnetic moment of Gd1–xREx alloy decreased with RE (RE= Pr, Nd) contentx increasing. The de Gennes factor of Gd1–xREx alloy which was associated with the exchange interaction between magnetic spin components also decreased with RE content increasing. The above results showed that the magnetic exchange interaction between magnetic atoms in gadolinium could be effectively changed by the Pr, Nd addition.

  1. The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia

    Science.gov (United States)

    Kappiyoor, Ravi; Liangruksa, Monrudee; Ganguly, Ranjan; Puri, Ishwar K.

    2010-11-01

    Magnetic fluid hyperthermia (MFH) is a noninvasive treatment that destroys cancer cells by heating a ferrofluid-impregnated malignant tissue with an ac magnetic field while causing minimal damage to the surrounding healthy tissue. The strength of the magnetic field must be sufficient to induce hyperthermia but it is also limited by the human ability to safely withstand it. The ferrofluid material used for hyperthermia should be one that is readily produced and is nontoxic while providing sufficient heating. We examine six materials that have been considered as candidates for MFH use. Examining the heating produced by nanoparticles of these materials, barium-ferrite and cobalt-ferrite are unable to produce sufficient MFH heating, that from iron-cobalt occurs at a far too rapid rate to be safe, while fcc iron-platinum, magnetite, and maghemite are all capable of producing stable controlled heating. We simulate the heating of ferrofluid-loaded tumors containing nanoparticles of the latter three materials to determine their effects on tumor tissue. These materials are viable MFH candidates since they can produce significant heating at the tumor center yet maintain the surrounding healthy tissue interface at a relatively safe temperature.

  2. Influence Of Nanoparticles Diameter On Structural Properties Of Magnetic Fluid In Magnetic Field

    Science.gov (United States)

    Kúdelčík, Jozef; Bury, Peter; Hardoň, Štefan; Kopčanský, Peter; Timko, Milan

    2015-07-01

    The properties of magnetic fluids depend on the nanoparticle diameter, their concentration and the carrier liquid. The structural changes in magnetic fluids with different nanoparticle diameter based on transformer oils TECHNOL and MOGUL under the effect of a magnetic field and temperature were studied by acoustic spectroscopy. At a linear and jump changes of the magnetic field at various temperatures a continuous change was observed of acoustic attenuation caused by aggregation of the magnetic nanoparticles to structures. From the anisotropy of acoustic attenuation and using the Taketomi theory the basic parameters of the structures are calculated and the impact of nanoparticle diameters on the size of structures is confirmed.

  3. Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

    Directory of Open Access Journals (Sweden)

    N. A. Zarkevich

    2014-03-01

    Full Text Available Low-temperature MnBi (hexagonal NiAs phase exhibits anomalies in the lattice constants (a, c and bulk elastic modulus (B below 100 K, spin reorientation and magnetic susceptibility maximum near 90 K, and, importantly for high-temperature magnetic applications, an increasing coercivity (unique to MnBi above 180  K. We calculate the total energy and magneto-anisotropy energy (MAE versus (a, c using DFT+U methods. We reproduce and explain all the above anomalies. We predict that coercivity and MAE increase due to increasing a, suggesting means to improve MnBi permanent magnets.

  4. Transport properties and anomalous fatigue effect of Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures

    International Nuclear Information System (INIS)

    The transport properties and fatigue effect of Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures are described. By examining the I—V curves, an anomalous fatigue effect was found and its influences on resistive states were studied. I—V curves combined with C—f spectra were used to directly analyze the transport properties and fatigue effect. Compared to the first I—V cycle state, this structure shows more than one order increase of resistance after 100 cycles of “I—V curve training”. The redistribution of oxygen vacancies in the depletion layer of Ag/Bi0.9La0.1FeO3 is believed to be responsible for the different resistance mechanisms and tenfold magnitude drop in resistance. The resistive switching is understood to be caused by electric field—induced carrier trapping and detrapping, which changes the depletion layer thickness at the Ag/Bi0.9La0.1FeO3 interface. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  5. Integrated On-line Instrumentation System of Magnetic Properties Measurement

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A portable microcomputer-controlled inspection system has been developed for detection of mag netic properties of soft magnetic materials. It incorporates custom designed software for control of the magnetic field during operation such as demagnetization, field sweeping, and for data logging and analysis. Results are recorded using a 12-bit analog to digital converter and are then stored on disk. The magnetic hysteresis loop and Barkhausen noise data can be converted into important magnetic parameters:, coecivity, remanence, and hysteresis loss, Barkhausen ampli tude, and Barkhausen noise energy. This system incorporated with the magnetostriction, and magnetoacoustic emission, is then related with the nondestructive detection of material degra dation.

  6. Thermal to electricity conversion using thermal magnetic properties

    Science.gov (United States)

    West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

    2010-04-27

    A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

  7. Magnetic properties of nanostructured CuFe2O4

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Goya, G.F.; Rechenberg, H.R.

    1999-01-01

    The structural evolution and magnetic properties of nanostructured copper ferrite, CuFe2O4, have been investigated by X-ray diffraction, Mossbauer spectroscopy, and magnetization measurements. Nanometre-sized CuFe2O4 particles with a partially inverted spinel structure were synthesized by high...... size while the coercive force, shift of the hysteresis loop, magnetic hardness, and saturation magnetization at 4.2 K increase with decreasing average grain size. At 295 K the coercive-field dependence on the average grain size is described, with particles showing superparamagnetic relaxation effects...

  8. Magnetic Properties of Iron Clusters in Silver

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Al Rawas, A.; Yousif, A.; Gismelseed, A.; Rais, A.; Al-Omari, I.; Bouziane, K. [College of Science, Department of Physics (Oman); Widatallah, H. [Khartoum University, Department of Physics, Faculty of Science (Sudan)

    2004-12-15

    The discrete variational method is used to study the effect of interactions of iron impurities on the magnetic moments, hyperfine fields and isomer shifts at iron sites in silver. We study small clusters of iron atoms as they grow to form FCC phase that is coherent with the silver lattice. The effects of the lattice relaxation and the ferromagnetic and antiferromagnetic couplings are also considered. When Fe atoms congregate around a central Fe atom in an FCC arrangement under ferromagnetic coupling, the local magnetic moment and the contact charge density at the central atom hardly change as the cluster builds up, whereas the hyperfine field increases asymptotically as the number of Fe nearest neighbors increases. Introduction of antiferromagnetic coupling has minor effect on the local magnetic moments and isomer shifts, however it produces large reduction in the hyperfine field. The lattice relaxation of the surrounding Fe atoms towards a BCC phase around a central Fe atom leads to reduction in the magnetic moment accompanied by increase in the magnetic hyperfine field.

  9. Enhancement of exchange coupling and hard magnetic properties in nanocomposites by magnetic annealing

    International Nuclear Information System (INIS)

    An enhancement of the exchange coupling and hard magnetic properties of melt-spun Nd2Fe14B/α-Fe-type nanocomposites was achieved by optimization of their nanostructured morphology via magnetic annealing. Compared with the Nd2.4Pr5.6Dy1Fe84Mo1B6 sample annealed without a magnetic field, the magnetic annealing results in a noticeable improvement in the coercivity i H c, the remanence 4πMr, and energy product (BH)max. (BH)max at 50 K was enhanced by 43.7% after magnetic annealing in a field of 19 T. The kink in the demagnetization curve disappeared and, additionally, a much better squareness of the demagnetization curves was observed in the magnetically annealed samples. The intergrain exchange coupling was evaluated by Henkel plots. Evidence for stronger intergrain exchange coupling was found in the magnetically annealed sample, which is due to nanostructure refinement promoted by the magnetic annealing. The nanostructure refinement was confirmed by X-ray diffraction, transmission electron microscope, low-temperature demagnetization curves and a modified Brown's equation analysis. The improvement of hard magnetic properties of the magnetically annealed sample results mainly from the magnetic-field-induced exchange-coupling enhancement

  10. Defective graphene and nanoribbons: electronic, magnetic and structural properties

    Science.gov (United States)

    Guerra, Thiago; Azevedo, Sérgio; Machado, Marcelo

    2016-03-01

    We make use of first-principles calculations, based on the density functional theory (DFT), to investigate the alterations at the structural, energetic, electronic and magnetic properties of graphene and zigzag graphene nanoribbons (ZGNRs) due to the inclusion of different types of line and punctual defects. For the graphene it is found that the inclusion of defects breaks the translational symmetry of the crystal with drastic changes at its electronic structure, going from semimetallic to semiconductor and metallic. Regarding the magnetic properties, no magnetization is observed for the defective graphene. We also show that the inclusion of defects at ZGNRs is a good way to create and control pronounced peaks at the Fermi level. Furthermore, defective ZGNRs structures show magnetic moment by supercell up to 2.0 μ B . For the non defective ZGNRs is observed a switch of the magnetic coupling between opposite ribbon edges from the antiferromagnetic to the ferrimagnetic and ferromagnetic configurations.

  11. Magnetic properties and thermodynamics in a metallic nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei, E-mail: weijiang.sut.edu@gmail.com; Li, Xiao-Xi; Guo, An-Bang; Guan, Hong-Yu; Wang, Zan; Wang, Kai

    2014-04-15

    A metallic nanotube composed of the ferromagnetic spin-3/2 inner shell and spin-1 outer shell with a ferrimagnetic interlayer coupling has been studied by using the effective-field theory with correlations (EFT). With both existence of the magnetic anisotropy and transverse field, we have studied effects of them on the magnetic properties and the thermodynamics. Some interesting phenomena have been found in the phase diagrams. At low temperature, the magnetization curves present different behaviors. Two compensation points have been found for the certain values of the system parameters in the system. The research results of metallic nanotubes may have potential applications in the fields of biomedicine and molecular devices. - Highlights: • A hexagonal metallic nanotube is composed of spin-3/2 inner layer and spin-1 outer layer. • Various types of magnetization curves depend on physical parameters and temperature. • We study the effects of physical parameters on the magnetic properties and thermodynamics.

  12. Magnetic properties and heavy metal contents of automobile emission particulates

    Institute of Scientific and Technical Information of China (English)

    LU Sheng-gao; BAI Shi-qiang; CAI Jing-bo; XU Chuang

    2005-01-01

    Measurements of the magnetic properties and total contents of Cu, Cd, Pb and Fe in 30 automobile emission particulate samples indicated the presence of magnetic particles in them. The values of frequency dependent susceptibility (χfd)showed the absence of superparamagnetic (SP) grains in the samples. The IRM20 mT (isothermal remanent magnetization at 20 mT)being linearly proportional to SIRM (saturation isothermal remanent magnetization) (R2=0.901), suggested that ferrimagnetic minerals were responsible for the magnetic properties of automobile emission particulates. The average contents of Cu, Cd, Pb and Fe in automobile emission particulates were 95.83, 22.14, 30.58 and 34727.31 mg/kg, respectively. Significant positive correlations exist between the magnetic parameters and the contents of Pb, Cu and Fe. The magnetic parameters of automobile emission particulates reflecting concentration of magnetic particles increased linearly with increase of Pb and Cu content, showed that the magnetic measurement could be used as a preliminary index for detection of Pb and Cu pollution.

  13. Nuclear magnetic resonance properties of lunar samples.

    Science.gov (United States)

    Kline, D.; Weeks, R. A.

    1972-01-01

    Nuclear magnetic resonance spectra of Na-23, Al-27, and P-31 in fines samples 10084,60 and 14163,168 and in crystalline rock samples 12021,55 and 14321,166, have been recorded over a range of frequencies up to 20 MHz. A shift in the field at which maximum absorption occurs for all of the spectra relative to the field at which maximum absorption occurs for terrestrial analogues is attributed to a sample-dependent magnetic field at the Na, Al, and P sites opposing the laboratory field. The magnitude of these fields internal to the samples is sample dependent and varies from 5 to 10 G. These fields do not correlate with the iron content of the samples. However, the presence of single-domain particles of iron distributed throughout the plagioclase fraction that contains the principal fraction of Na and Al is inferred from electron magnetic resonance spectra shapes.

  14. Magnetic properties on strained manganite thin film

    Science.gov (United States)

    Prajapat, C. L.; Singh, M. R.; Gupta, S. K.; Bhattacharya, D.; Basu, S.; Ravikumar, G.

    2014-04-01

    Structural and magnetic studies on La2/3Sr1/3MnO3 (LSMO) epitaxial films grown on STO (100) and MgO (100) substrates by Pulsed Laser Deposition are presented. Due to larger interface strain, the grain size of LSMO on MgO is much smaller than that on STO substrate. However, anisotropy energy produced as a result of in plane tensile strain is much larger in case of the films deposited on MgO in such a way that the blocking (irreversibility) temperature and the coercive fields inferred from temperature and magnetic field dependent magnetization measurements are significantly higher. The importance of this result for the memory applications is highlighted.

  15. Magnetic Co3O4 nanowires,preparation and properties

    Institute of Scientific and Technical Information of China (English)

    Mai Xia Ma; Wei Meng Chen; Lin Guo; Jing Hong Li; Chin Ping Chen; Shi He Yang

    2012-01-01

    The Co3O4 nanowires have been successfully synthesized via modified template method.The as-prepared products have been characterized by EDS,TEM and HRTEM analysis.The magnetic behavior of it is investigated by a magnetic property measurement system.The nanowires exhibit some novel magnetic properties,which are different from its bulk material.The temperature dependence curves of magnetization in zero-field-cooling and field-cooling exhibit two peaks of antiferromagnetic at blocking temperature of ~23 K and ~31 K,respectively.The field dependent M(H) curves of the Co3O4 nanowires at T =5 and 300 K both exhibit PM properties.Moreover,the diameter of nanowires is hence determined according to the finite size effect as approximately 7-11 nm,in consistent with the characterizations by HRTEM.

  16. Magnetic properties of nanocrystalline FeNiN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, P.; Sanz, J.M. [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales ' ' Nicolas Cabrera' ' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Camarero, J.; Sacristan, N. [Departamento de Fisica de la Materia Condensada and Instituto de Ciencia de Materiales ' ' Nicolas Cabrera' ' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Boerma, D.O. [Departamento de Fisica de la Materia Condensada and Centro de Micro Analisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2006-05-15

    FeNiN thin films with a Ni content varying between 5 and 36 at% (as determined by X-ray photoelectron spectroscopy) have been deposited in a Dual Ion Beam Sputtering System at room temperature. The structure and crystalline size were studied by X-ray diffraction while the magnetic properties were investigated by vectorial kerr magnetometry. In general, the deposited films present a nanocrystaline cubic structure and well defined in-plane magnetic anisotropy. The variation of the magnetic properties was attributed to changes in composition and nanocrystalline structure. FeNiN thin films with a Ni content of about 15 at% show the better soft magnetic properties with a minimum in the coercivity of 9 Oe. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Spectral Properties of the Martian Crustal Magnetic Field

    Science.gov (United States)

    Lewis, K. W.; Simons, F. J.

    2010-12-01

    Although the planet Mars no longer possesses an internal dynamo, its crustal rocks retain strong remanent magnetization thought to have been induced by an ancient core-sourced field. The strength and distribution of the crustal field is extremely heterogeneous, and particularly strong in the Terra Cimmeria region of the southern hemisphere. The field as a whole is inconsistent with induction from a single dipolar source, although previous studies have attempted to isolate individual magnetic anomalies to deduce paleopolar orientations. While several areas of the planet appear to have been demagnetized, including large impact basins and the Tharsis volcanic province, the distribution of the field is generally poorly correlated with surface geologic structures. However, beyond the spatial pattern of crustal magnetization, the magnetic power spectrum can provide information about the nature of the source and formation processes. Previous studies have used the power spectrum of the Martian field to estimate the approximate depth of the magnetic anomalies. We extend this approach by applying the spatiospectral localization technique of Wieczorek and Simons (2005) and Dahlen and Simons (2008) to isolate the magnetic power spectra of several areas of the Martian surface. This method allows us to look beyond the strongly magnetized Terra Cimmeria region, which dominates the global power spectrum. Localized spectral estimates, along with their appropriate errors, allow us to examine the significance of observed variations between distinct regions of the planet, and to evaluate the validity of analyses which operate on the whole sphere. Significant differences are observed between spectra of the Terra Cimmeria region and the remainder of the planet, a result of the concentration of power at certain spherical harmonic degrees in this anomalous region. Approximate depths to the magnetic sources are calculated for tiled windows on the planet using the stochastic magnetized

  18. Estimation Model for Magnetic Properties of Stamped Electrical Steel Sheet

    Science.gov (United States)

    Kashiwara, Yoshiyuki; Fujimura, Hiroshi; Okamura, Kazuo; Imanishi, Kenji; Yashiki, Hiroyoshi

    Less deterioration in magnetic properties of electrical steel sheets in the process of stamping out iron-core are necessary in order to maintain its performance. First, the influence of plastic strain and stress on magnetic properties was studied by test pieces, in which plastic strain was added uniformly and residual stress was not induced. Because the influence of plastic strain was expressed by equivalent plastic strain, at each equivalent plastic strain state the influence of load stress was investigated. Secondly, elastic limit was determined about 60% of macroscopic yield point (MYP), and it was found to agree with stress limit inducing irreversible deterioration in magnetic properties. Therefore simulation models, where beyond elastic limit plastic deformation begins and magnetic properties are deteriorated steeply, are proposed. Besides considered points in the deformation analysis are strain-rate sensitivity of flow stress, anisotropy under deformation, and influence of stress triaxiality on fracture. Finally, proposed models have been shown to be valid, because magnetic properties of 5mm width rectangular sheets stamped out from non-oriented electrical steel sheet (35A250 JIS grade) can be estimated with good accuracy. It is concluded that the elastic limit must be taken into account in both stamping process simulation and magnetic field calculation.

  19. Superconductivity and magnetism: Materials properties and developments

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, N.H.; Bay, N.; Grivel, J.C. (eds.) [and others

    2003-07-01

    The 24th Risoe International Symposium on Materials Science focuses on development of new materials, devices and applications, as well as experimental and theoretical studies of novel and unexplained phenomena in superconductivity and magnetism, e.g. within high.T{sub c} superconductivity, magnetic superconductors, MgB{sub 2}, CMR materials, nanomagnetism and spin-tronics. The aim is to stimulate exchange of ideas and establish new collaborations between leading Danish and international scientists. The topics are addressed by presentations from 24 invited speakers and by 41 contributed papers. (ln)

  20. Superconductivity and magnetism: Materials properties and developments

    International Nuclear Information System (INIS)

    The 24th Risoe International Symposium on Materials Science focuses on development of new materials, devices and applications, as well as experimental and theoretical studies of novel and unexplained phenomena in superconductivity and magnetism, e.g. within high.Tc superconductivity, magnetic superconductors, MgB2, CMR materials, nanomagnetism and spin-tronics. The aim is to stimulate exchange of ideas and establish new collaborations between leading Danish and international scientists. The topics are addressed by presentations from 24 invited speakers and by 41 contributed papers. (ln)

  1. Remanence Properties and Magnetization Reversal Mechanism of Fe Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Bo; LIU Qing-Fang; XUE De-Sheng; LI Fa-Shen

    2004-01-01

    @@ Remanence properties and magnetization reversal mechanism of Fe nanowire arrays with diameters 16 nm and130nm are studied. Isothermal remanent magnetization curves show that the contribution of irreversible magnetization decreases when the diameter changes from 16nm to 130nm. The remanence coercivities of these nanowires obtained in dc-demagnetization curve are about 2400 Oe and 800 Oe, respectively. The magnetization reversal mechanism is different in these two samples. For the nanowire array with diameter 16nm, both the nucleation and the pinning have effects on magnetization reversal mechanism, and the pinning field (about 2500Oe) is larger than the nucleation field (about 2200 Oe). However, for the nanowire array with diameter 130nm,the magnetization reversal mechanism is dominated by the pinning effect of domain walls.

  2. The structural and magnetic properties of holmium/scandium superlattices

    DEFF Research Database (Denmark)

    Bryn-Jacobsen, C.; Cowley, R.A.; McMorrow, D.F.;

    1997-01-01

    The properties of Ho/Sc superlattices grown by molecular beam epitaxy (MBE) have been investigated using X-ray and neutron diffraction techniques. Structural studies reveal the novel existence of more than one a lattice parameter. Examining the magnetic properties, it is found that the Ho 4f...

  3. Theoretical description of anomalous properties of novel room temperature multiferroics Pb(Fe1/2Ta1/2)x(Zr0.53Ti0.47)1-xO3 and Pb(Fe1/2Nb1/2)x(Zr0.53Ti0.47)1-xO3

    OpenAIRE

    Glinchuk, Maya D.; Eliseev, Eugene A.; Morozovska, Anna N.

    2015-01-01

    The theoretical description of the anomalous ferroelectric, ferromagnetic and magnetoelectric properties of Pb(Fe1/2Ta1/2)x(Zr0.53Ti0.47)1-xO3 and Pb(Fe1/2Nb1/2)x(Zr0.53Ti0.47)1-xO3 micro-ceramics is given. We performed calculations of temperature, composition and external field dependence of ferroelectric, ferromagnetic and antiferromagnetic phases transition temperatures, remanent polarization, magnetization, hysteresis loops, coercive fields, dielectric permittivity and magnetoelectric cou...

  4. Magnetic Properties of Quantum Ferrimagnetic Spin Chains

    OpenAIRE

    Yamamoto, Shoji

    1998-01-01

    Magnetic susceptibilities of spin-$(S,s)$ ferrimagnetic Heisenberg chains are numerically investigated. It is argued how the ferromagnetic and antiferromagnetic features of quantum ferrimagnets are exhibited as functions of $(S,s)$. Spin-$(S,s)$ ferrimagnetic chains behave like combinations of spin-$(S-s)$ ferromagnetic and spin-$(2s)$ antiferromagnetic chains provided $S=2s$.

  5. Magnetic property and microstructure of SmCo magnetic recording films

    Institute of Scientific and Technical Information of China (English)

    LI; Ning; LI; Shuai

    2009-01-01

    Cr/SmCo/Cr thin films with Sm concentration of 37.7 at.% were deposited on glass substrates by magnetron sputtering. Meas-urement of magnetic properties showed that the SmCo film possessed good magnetic anisotropy, a high coercivity of 3019 kA/m and low magnetic exchange coupling. Microstructure analysis showed that crystallized SmCo5 magnetic phase, non-magnetic SmCo2 phase and Sm2Co7 phase co-existed ill the film. The non-magnetic SmCo2 phase might function as isolator of SmCo grains, leading to a decrease of magnetic exchange coupling. Moreover, a Cr2)3 oxide layer which could protect the SmCo layer from oxidation formed at the surface of the Cr cap layer.

  6. Magnetic properties of a classical XY spin dimer in a "planar" magnetic field

    Science.gov (United States)

    Ciftja, Orion; Prenga, Dode

    2016-10-01

    Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a "planar" external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin-spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks.

  7. The role of electrolyte pH on phase evolution and magnetic properties of CoFeW codeposited films

    Science.gov (United States)

    Ghaferi, Z.; Sharafi, S.; Bahrololoom, M. E.

    2016-07-01

    In this research, nanocrystalline Co-Fe-W alloy coatings were electrodeposited from a citrate-borate bath. The influence of electrolyte pH on the morphology, microstructure and magnetic properties of these films was also studied. By increasing pH value, the amount of iron content increased from 30 to 55 wt.% which indicates anomalous fashion at higher pH electrolytes. X-ray diffraction patterns showed that the structure of these films depend on electrolyte pH effectively. However, two-phase structure coatings showed smaller average grain size compared with one- phase solid solutions. Vibrating sample magnetometer measurements indicated that the coercivity of the coatings was in the range of 21-76 Oe. However, the highest pH value produced coating with superior magnetic behaviour. Microhardness of the coatings reached its maximum value at about 260HV which is referred to the highest tungsten content.

  8. Diagnosing the Properties of the Solar Wind using Magnetic Topology

    Science.gov (United States)

    Mikic, Z.; Titov, V. S.; Lionello, R.; Downs, C.; Linker, J.; Torok, T.; Riley, P.

    2015-12-01

    Recent work suggests that the topology of the coronal magnetic field plays a key role in the source and properties of the slow solar wind, through the collection of separatrix surfaces and quasi-separatrix layers (QSLs) that define the S-web (Antiochos et al. 2011; Linker et al. 2011; Titov et al. 2011). We have accumulated extensive experience with using the squashing factor Q to analyze the underlying structural skeleton of the coronal magnetic field, to identify magnetic null points, separator field lines, QSLs, and separatrix surfaces, and their relationship with the topology of coronal hole boundaries. This will be extended by implementing slip mapping (Titov et al. 2009) to detect open, closed, and disconnected flux systems that are formed due to magnetic reconnection in a coronal model driven by both the differential rotation and evolution of the photospheric magnetic field. This idea is based on using forward and backward differences in time between the field line mapping expected from ideal MHD motions and the actual mapping to diagnose magnetic reconnection. This technique can identify regions in the photosphere where closed magnetic field lines are about to open (e.g., via interchange reconnection), and conversely, where open field lines are about to close. We will use these concepts to develop tools that relate the changing magnetic topology to the properties of the solar wind, to plan and interpret Solar Probe Plus and Solar Orbiter observations. Research supported by NASA's Living With a Star Program.

  9. Defect energetics and magnetic properties of 3 d-transition-metal-doped topological crystalline insulator SnTe

    Science.gov (United States)

    Wang, Na; Wang, JianFeng; Si, Chen; Gu, Bing-Lin; Duan, WenHui

    2016-08-01

    The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have studied the defect energetics and magnetic properties of 3 d transition-metal (TM)-doped SnTe. We find that the doped TM atoms prefer to stay in the neutral states and have comparatively high formation energies, suggesting that the uniform TMdoping in SnTe with a higher concentration will be difficult unless clustering. In the dilute doping regime, all the magnetic TMatoms are in the high-spin states, indicating that the spin splitting energy of 3 d TM is stronger than the crystal splitting energy of the SnTe ligand. Importantly, Mn-doped SnTe has relatively low defect formation energy, largest local magnetic moment, and no defect levels in the bulk gap, suggesting that Mn is a promising magnetic dopant to realize the magnetic order for the theoretically-proposed large-Chern-number quantum anomalous Hall effect (QAHE) in SnTe.

  10. Tenth-Order QED contribution to Lepton Anomalous Magnetic Moment - Fourth-Order Vertices Containing Sixth-Order Vacuum-Polarization Subdiagrams

    CERN Document Server

    Aoyama, T; Kinoshita, T; Nio, M

    2011-01-01

    This paper reports the tenth-order contributions to the g-2 of the electron a_e and those of the muon a_mu from the gauge-invariant Set II(c), which consists of 36 Feynman diagrams, and Set II(d), which consists of 180 Feynman diagrams. Both sets are obtained by insertion of sixth-order vacuum-polarization diagrams in the fourth-order anomalous magnetic moment. The mass-independent contributions from Set II(c) and Set II(d) are -0.116 489 (32)(alpha/pi)^5 and -0.243 00 (29)(alpha/pi)^5, respectively. The leading contributions to a_mu, which involve electron loops only, are -3.888 27 (90)(alpha/pi)^5 and 0.4972 (65)(alpha/pi)^5 for Set II(c) and Set II(d), respectively. The total contributions of the electron, muon, and tau-lepton loops to a_e are -0.116 874 (32) (alpha/pi)^5 for Set II(c) and -0.243 10 (29) (alpha/pi)^5 for Set II(d). The contributions of electron, muon, and tau-lepton loops to a_mu are -5.5594 (11) (alpha/pi)^5 for Set II(c) and 0.2465 (65) (alpha/pi)^5 for Set II(d).

  11. Magnetic properties of rare earth superlattices

    CERN Document Server

    Wilkins, C J T

    2001-01-01

    Single-crystal Tm/Y and Tm/Lu superlattices have been grown using molecular beam epitaxy and their chemical structures have been determined using X-ray diffraction. Magnetisation measurements have revealed a more complicated phase diagram than that of pure Tm. Application of a field along the c-direction gave rise to an extra transition, and transitions were detected for the superlattices when the field was applied along the b-axis. In neutron diffraction studies, c-axis longitudinally modulated magnetic structures were found for both Tm/Y and Tm/Lu, which propagate coherently through the non-magnetic layers. In the case of Tm/Lu superlattices, there is evidence for ordering of the basal plane components.

  12. Magnetic properties of nano-composite particles

    Science.gov (United States)

    Xu, Xia

    Chemical synthesis routes for hollow spherical BaFe12O 19, hollow mesoporous spherical BaFe12O19, worm-shape BaFe12O19 and FeCo particles were developed. These structured particles have great potentials for the applications including magnetic recording medium, catalyst support, and energy storage. Magnetically exchange coupled hard/soft SrFe12O19/FeCo and MnBi/FeCo composites were synthesized through a newly proposed process of magnetic self-assembly. These exchange coupled composites can be potentially used as rare-earth free permanent magnets. Hollow spherical BaFe12O19 particles (shell thickness ˜5 nm) were synthesized from eth-ylene glycol assisted spray pyrolysis. Hollow mesoporous spherical BaFe12O19 particles (shell thickness ˜100 nm) were synthesized from ethanol assisted spray pyrolysis, followed by alkaline ethylene glycol etching at 185 °C. An alpha-Fe2O3 and BaCO3 nanoparticle mixture was synthesized with reverse microemulsion, followed by annealing at 900 °C for 2 hours to get worm-shape BaFe 12O19 particles, which consisted of 3-7 stacked hexagonal plates. FeCo nanoparticles were synthesized by reducing FeCl2 and CoCl2 in diphenyl ether with n-butyllithium at 200 °C in an inert gas environment. The surfactant of oleic acid was used in the synthesis to make particles well dispersed in nonpolar solvents (such as hexane). SrFe12O19/FeCo core/shell particles were prepared through a magnetic self-assembly process. The as-synthesized soft FeCo nanoparticles were magnetically attracted by hard SrFe12O19 parti-cles, forming a SrFe12O19/FeCo core/shell structure. The magnetic self-assembly mechanism was confirmed by applying alternating-current demagnetization to the core/shell particles, which re-sulted in a separation of SrFe 12O19 and FeCo particles. MnBi/FeCo composites were synthesized, and the exchange coupling between MnBi and FeCo phases was demonstrated by smooth magnetic hysteresis loop of MnBi/FeCo composites. The thermal stability of Mn

  13. Magnetic properties of dipolar chains in ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Avgin, I., E-mail: ihavgin@gmail.com [Department of Electrical Engineering, Ege University, Izmir (Turkey); Huber, D.L. [Physics Department, University of Wisconsin-Madison, Madison, WI (United States)

    2014-07-01

    We have investigated the dipole interaction energies per particle and the local dipole field distributions in a frozen magnetization model of a ferrofluid chain in a saturating magnetic field. A lognormal distribution of particle diameters was assumed. The interaction energies were calculated for one dimensional arrays of dipoles with moments parallel to the chain. We have computed the energies by various approximations related to the hard sphere particle diameter distribution. A similar approach was followed for the local field distributions. It was found that the energy per particle and mean local field were largely determined by the mean particle diameter, but the distribution of local fields was sensitive to both the mean diameter and the assumptions about spatial correlations between particles of different size. Detailed results are presented for water-soluble Fe{sub 3}O{sub 4}/PAA (polyacrylic acid). (author)

  14. Magnetic properties of Cr telluride-selenide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mankovsky, Sergey; Polesya, Svetlana; Ebert, Hubert [Dept. Chemie und Biochemie, Universitaet Muenchen, Butenandtstr. 5-13, D-81377 Muenchen (Germany); Huang, Zhong-Le; Bensch, Wolfgang [Institute for Anorganic Chemistry, Olshausenstr. 40, D-24098, Kiel (Germany)

    2007-07-01

    Results of a theoretical study of the magnetic properties of Cr telluride-selenide alloys having trigonal crystal structure are presented in comparison with experimental results. Both ground state and temperature-dependent magnetic properties of Cr{sub 1-{delta}}Te and Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} (with ratio {alpha}:{beta}=7:1,6:2,5:3) have been investigated in a wide region of chromium content. For the alloys Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} a transition to the state with antiferromagnetic order in a fully occupied sub-lattice and with no order in a partially occupied sub-lattice was obtained. For the alloys Li{sub x}Cr{sub 0.5}Ti{sub 0.75}Se{sub 2}, a non-monotonic dependence of structural and magnetic properties have been found upon increase of Li concentration x, that is in agreement with experimental results. The ground state properties have been studied on the basis of electronic structure calculations using the Korringa-Kohn-Rostoker (KKR) band structure method combined with the CPA alloy theory. Using Monte Carlo simulations we obtained the magnetic configuration at T=0 K and studied the magnetic properties at T>0 K as well. The required exchange coupling parameters were obtained from our ab-initio electronic structure calculations.

  15. The correlations between processing parameters and magnetic properties of an iron-resin soft magnetic composite

    Energy Technology Data Exchange (ETDEWEB)

    Hemmati, I. [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of); Madaah Hosseini, H.R. [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)]. E-mail: madaah@sharif.edu; Kianvash, A. [Department of Ceramic Engineering, Faculty of Engineering, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of)

    2006-10-15

    In this study, internal microstrain of an iron-resin composite produced by powder metallurgy has been calculated using the Williamson-Hall method. The effects of microstrain evolution during different processing conditions on magnetic properties such as coercive force and hysteresis loss have been investigated. The results show that there are regular and similar changes of coercivity and hysteresis loss. Both of these properties are directly dependant on the pinning effect of the internal microstrain against the movement of magnetic domain walls during magnetization process.

  16. Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

    DEFF Research Database (Denmark)

    Snigirev, O.V.; Andreev, K.E.; Tishin, A.M.;

    1997-01-01

    We have applied a scanning HTS (high-temperature superconductor) de SQUID (superconducting quantum interference device) -based magnetic microscope to study the magnetic properties of Au/Ni/Si(100) films in the thickness range from 8 to 200 Angstrom at T = 77 K. A one-domain structure with in......-plane orientation of the magnetic moment was found for film thicknesses exceeding 26 Angstrom. A drastic decrease of the magnetization of the film was detected when the thickness is less than 26 Angstrom....

  17. Magnetically textured ferrofluid in a non-magnetic matrix: Magnetic properties

    Indian Academy of Sciences (India)

    Mrudul Gadhvi; R V Upadhyay; Kinnari Parekh; R V Mehta

    2004-04-01

    Texturing of two different magnetic fluids were carried out in paraffin wax under the influence of an external magnetic field. The textured samples were characterized using magnetization measurement and a.c. susceptibility techniques. The results are discussed in the light of ratio of anisotropic energy to magnetic and thermal energies.

  18. Magnetic properties of spark plasma sintering magnets using fine powders prepared by mechanical compounding method

    International Nuclear Information System (INIS)

    Sr-La-Co M-type ferrite fine particles were prepared by mechanical compounding (MC) method using the planetary ball-mill and subsequent heat treatment. This experiment was carried out to investigate the magnetic properties of Sr-La-Co M-type ferrite magnets prepared by spark plasma sintering (SPS) method using powders made by the MC method. The optimum condition of making SPS magnet, and some properties of a typical specimen are as follows: chemical composition, SrO·6.0Fe2O3; additives, 1.0 wt% La2O3 and 0.1 wt% Co3O4; pressing pressure, 50 MPa; sintering condition: 1100 deg. Cx5 min. Magnetic and physical properties are Br=0.323 T, HcJ=325 kA/m, (BH)max=18.3 kJ/m3, and density=5.15 Mg/m3

  19. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    OpenAIRE

    Bashar Issa; Obaidat, Ihab M.; Albiss, Borhan A.; Yousef Haik

    2013-01-01

    Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm), viruses, genes, down to proteins (3–50 nm). The opti...

  20. PHASE TRANSITION PROPERTIES OF A TWO COMPONENT FINITE MAGNETIC SUPERLATTICE

    Institute of Scientific and Technical Information of China (English)

    WANG XIAO-GUANG; LIU NING-NING; PAN SHAO-HUA; YANG GUO-ZHEN

    2000-01-01

    We study an (l, n) finite superlattice, which consists of two alternative magnetic materials(components) of l and n atomic layers, respectively. Based on the Ising model, we examine the phase transition properties of the magnetic superlattice. By transfer matrix method we derive the equation for Curie temperature of the superlattice. Numerical results are obtained for the dependence of Curie temperature on the thickness and exchange constants of the superlattice.

  1. GEMAS: unmixing magnetic properties of European agricultural soil

    OpenAIRE

    Fabian, Karl; Reimann, Clemens; Kuzina, Dilyara; Kosareva, Lina; Fattakhova, Leysan; Nurgaliev, Danis; Flight, Dee; Johnson, Christopher; Scheib, Andreas

    2016-01-01

    High resolution magnetic measurements provide new methods for world-wide characterization and monitoring of agricultural soil which is essential for quantifying geologic and human impact on the critical zone environment and consequences of climatic change, for planning economic and ecological land use, and for forensic applications. Hysteresis measurements of all Ap samples from the GEMAS survey yield a comprehensive overview of mineral magnetic properties in European agricultural soil on a c...

  2. Magnetic Properties of Bismuth Ferrite Nanopowder Obtained by Mechanochemical Synthesis

    OpenAIRE

    Szafraniak-Wiza, I.; Andrzejewski, B.; Hilczer, B.

    2014-01-01

    Multiferroic bismuth ferrite (BiFeO3) nanopowders have been obtained in room temperature by mechanical synthesis. Depending on the post-synthesis processing the nanopowders have exhibited differences in the mean sizes, presence of amorphous layer and/or secondary phases. Extended magnetic study performed for fresh, annealed and hot-pressed nanopowders have revealed substantial improvement of the magnetic properties in the as-prepared powder.

  3. Evaluating the effect of magnetocaloric properties on magnetic refrigeration performance

    OpenAIRE

    Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2010-01-01

    Active magnetic regenerator (AMR) refrigerators represent an alternative to vapor compression technology that relies on the magnetocaloric effect in a solid refrigerant. Magnetocaloric materials are in development and properties are reported regularly. Recently, there has been an emphasis on developing materials with a high entropy change with magnetization while placing lower emphasis on the adiabatic temperature change. This work uses model magnetocaloric materials and a numerical AMR model...

  4. GEMAS: Unmixing magnetic properties of European agricultural soil

    Science.gov (United States)

    Fabian, Karl; Reimann, Clemens; Kuzina, Dilyara; Kosareva, Lina; Fattakhova, Leysan; Nurgaliev, Danis

    2016-04-01

    High resolution magnetic measurements provide new methods for world-wide characterization and monitoring of agricultural soil which is essential for quantifying geologic and human impact on the critical zone environment and consequences of climatic change, for planning economic and ecological land use, and for forensic applications. Hysteresis measurements of all Ap samples from the GEMAS survey yield a comprehensive overview of mineral magnetic properties in European agricultural soil on a continental scale. Low (460 Hz), and high frequency (4600 Hz) magnetic susceptibility k were measured using a Bartington MS2B sensor. Hysteresis properties were determined by a J-coercivity spectrometer, built at the paleomagnetic laboratory of Kazan University, providing for each sample a modified hysteresis loop, backfield curve, acquisition curve of isothermal remanent magnetization, and a viscous IRM decay spectrum. Each measurement set is obtained in a single run from zero field up to 1.5 T and back to -1.5 T. The resulting data are used to create the first continental-scale maps of magnetic soil parameters. Because the GEMAS geochemical atlas contains a comprehensive set of geochemical data for the same soil samples, the new data can be used to map magnetic parameters in relation to chemical and geological parameters. The data set also provides a unique opportunity to analyze the magnetic mineral fraction of the soil samples by unmixing their IRM acquisition curves. The endmember coefficients are interpreted by linear inversion for other magnetic, physical and chemical properties which results in an unprecedented and detailed view of the mineral magnetic composition of European agricultural soils.

  5. Magnetic properties of nanostructured CuFe2O4

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Goya, G.F.; Rechenberg, H.R.

    1999-01-01

    The structural evolution and magnetic properties of nanostructured copper ferrite, CuFe2O4, have been investigated by X-ray diffraction, Mossbauer spectroscopy, and magnetization measurements. Nanometre-sized CuFe2O4 particles with a partially inverted spinel structure were synthesized by high...... size while the coercive force, shift of the hysteresis loop, magnetic hardness, and saturation magnetization at 4.2 K increase with decreasing average grain size. At 295 K the coercive-field dependence on the average grain size is described, with particles showing superparamagnetic relaxation effects......-energy ball milling in an open container with grain sizes ranging from 9 to 61 nm. Superparamagnetic relaxation effects have been observed in milled samples at room temperature by Mossbauer and magnetization measurements. At 15 K, the average hyperfine field of CuFe2O4 decreases with decreasing average grain...

  6. Dust properties and magnetic field geometry towards LDN 1570

    Science.gov (United States)

    Eswaraiah, C.; Maheswar, G.; Pandey, A. K.

    2015-03-01

    We have performed both optical linear polarimetric and photometric observations of an isolated dark globule LDN 1570 aim to study the dust polarizing and extinction properties and to map the magnetic field geometry so as to understand not only the importance of magnetic fields in formation and evolution of clouds but also the correlation of the inferred magnetic field structure with the cloud structure and its dynamics. Dust size indicators (R V and λ max ) reveal for the presence of slightly bigger dust grains towards the cloud region. The inferred magnetic field geometry, which closely follows the cloud structure revealed by Herschel images, suggest that the cloud could have been formed due to converging material flows along the magnetic field lines.

  7. Structural and magnetic properties of granular CoPd multilayers

    Science.gov (United States)

    Vivas, L. G.; Figueroa, A. I.; Bartolomé, F.; Rubín, J.; García, L. M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J. M.; Brookes, N. B.; Wilhelm, F.; Rogalev, A.; Bartolomé, J.

    2016-02-01

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk.

  8. Structure, synthetic methods, magnetic properties and biomedical applications of ferrofluids.

    Science.gov (United States)

    Shokrollahi, H

    2013-07-01

    This paper is aimed at conducting a survey of the synthetic methods and magnetic properties of nanoparticles as ferrofluids used in biomedicine. As compared with other works in the field, the distinctive feature of the current work is the systematic study of recent advances in ferrofluids utilized in hyperthermia and magnetic resonance imaging (MRI). The most important feature for application of ferrofluids is super-paramagnetic behavior of magnetic cores with relatively high saturation magnetization. Although Fe3O4 nanoparticles have traditionally been used in medicine; the modified Mn-ferrite has recently received special attention due to its higher saturation magnetization and r2-relaxivity as a contrast agent in MRI. Co-ferrite nanoparticles are also good candidates for hyperthermia treatment because of their high coercivity and magnetocrystalline anisotropy. The thermal decomposition and hydrothermal methods are good candidates for obtaining appropriate super-paramagnetic particles. PMID:23623058

  9. Effects of temperature and Nickel content on magnetic properties of Ni-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    REN Lingling; JEUNG Won Young

    2006-01-01

    Magnetic properties of diluted magnetic semiconductors (DMSs), Ni-doped ZnO materials, prepared by sol-gel method were investigated by measuring magnetization as functions of magnetic field.The Ni content affects the magnetic properties at low sintered temperature but it has few effects on the magnetic properties at high sintered temperature.The sintered temperature has great effects on the magnetic properties of Ni/ZnO at high original mole ratio of Ni/Zn while it has slight effects on the magnetic properties of Ni/ZnO at low original mole ratio of Ni/Zn whatever low or high sintered temperature.

  10. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    Science.gov (United States)

    Issa, Bashar; Obaidat, Ihab M.; Albiss, Borhan A.; Haik, Yousef

    2013-01-01

    Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm), viruses, genes, down to proteins (3–50 nm). The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents. PMID:24232575

  11. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    Directory of Open Access Journals (Sweden)

    Bashar Issa

    2013-10-01

    Full Text Available Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm, viruses, genes, down to proteins (3–50 nm. The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents.

  12. Particle size dependent rheological property in magnetic fluid

    Science.gov (United States)

    Wu, Jie; Pei, Lei; Xuan, Shouhu; Yan, Qifan; Gong, Xinglong

    2016-06-01

    The influence of the particle size on the rheological property of magnetic fluid was studied both by the experimental and computer simulation methods. Firstly, the magnetic fluids were prepared by dispersing Fe3O4 nanospheres with size varied from 40 nm to 100 nm and 200 nm in the solution. Then, the rheological properties were investigated and it was found that the relative magnetorheological effects increased with increasing the particle size. Finally, the molecular dynamic simulation was used to analyze the mechanical characteristics of the magnetic fluid and the chain-like model agreed well with the experimental result. The authentic chain-like structure observed by a microscope agreed with the simulation results. The three particles composed of the similar cluster nanostructure, thus they exhibited similar magnetic property. To this end, the unique assembling microstructures was the origination of the mechanical difference. And it was found that the higher MR (magnetorheological) effects of the large particle based magnetic fluid was originated from the stronger assembling microstructure under the applying magnetic field.

  13. Single crystal Processing and magnetic properties of gadolinium nickel

    Energy Technology Data Exchange (ETDEWEB)

    Shreve, Andrew John [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    GdNi is a rare earth intermetallic material that exhibits very interesting magnetic properties. Spontaneous magnetostriction occurs in GdNi at T{sub C}, on the order of 8000ppm strain along the c-axis and only until very recently the mechanism causing this giant magnetostriction was not understood. In order to learn more about the electronic and magnetic structure of GdNi, single crystals are required for anisotropic magnetic property measurements. Single crystal processing is quite challenging for GdNi though since the rare-earth transition-metal composition yields a very reactive intermetallic compound. Many crystal growth methods are pursued in this study including crucible free methods, precipitation growths, and specially developed Bridgman crucibles. A plasma-sprayed Gd2O3 W-backed Bridgman crucible was found to be the best means of GdNi single crystal processing. With a source of high-quality single crystals, many magnetization measurements were collected to reveal the magnetic structure of GdNi. Heat capacity and the magnetocaloric effect are also measured on a single crystal sample. The result is a thorough report on high quality single crystal processing and the magnetic properties of GdNi.

  14. Electronic, magnetic and transport properties of rare-earth monopnictides.

    Science.gov (United States)

    Duan, Chun-Gang; Sabirianov, R F; Mei, W N; Dowben, P A; Jaswal, S S; Tsymbal, E Y

    2007-08-01

    The electronic structures and magnetic properties of many rare-earth monopnictides are reviewed in this article. Possible candidate materials for spintronics devices from the rare-earth monopnictide family, i.e. high polarization (nominally half-metallic) ferromagnets and antiferromagnets, are identified. We attempt to provide a unified picture of the electronic properties of these strongly correlated systems. The relative merits of several ab initio theoretical methods, useful in the study of the rare-earth monopnictides, are discussed. We present our current understanding of the possible half-metallicity, semiconductor-metal transitions, and magnetic orderings in the rare-earth monopnictides. Finally, we propose some potential strategies to improve the magnetic and electronic properties of these candidate materials for spintronics devices. PMID:21694120

  15. Electronic, magnetic and transport properties of rare-earth monopnictides

    Energy Technology Data Exchange (ETDEWEB)

    Duan, C-G [Department of Physics, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Sabirianov, R F [Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Mei, W N [Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Dowben, P A [Department of Physics, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Jaswal, S S [Department of Physics, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Tsymbal, E Y [Department of Physics, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

    2007-08-08

    The electronic structures and magnetic properties of many rare-earth monopnictides are reviewed in this article. Possible candidate materials for spintronics devices from the rare-earth monopnictide family, i.e. high polarization (nominally half-metallic) ferromagnets and antiferromagnets, are identified. We attempt to provide a unified picture of the electronic properties of these strongly correlated systems. The relative merits of several ab initio theoretical methods, useful in the study of the rare-earth monopnictides, are discussed. We present our current understanding of the possible half-metallicity, semiconductor-metal transitions, and magnetic orderings in the rare-earth monopnictides. Finally, we propose some potential strategies to improve the magnetic and electronic properties of these candidate materials for spintronics devices.

  16. Magnetoactive elastomeric composites: Cure, tensile, electrical and magnetic properties

    Indian Academy of Sciences (India)

    K Sasikumar; G Suresh; K A Thomas; Reji John; V Natarajan; T Mukundan; R M R Vishnubhatla

    2006-11-01

    Magnetically active elastomer materials were prepared by incorporating nickel powder in synthetic elastomeric matrices, polychloroprene and nitrile rubber. Cure characteristics, mechanical, electrical and magnetic properties were experimentally determined for different volume fractions of magnetoactive filler. The cure time decreases sharply for initial filler loading and the decrease is marginal for additional loading of filler. The tensile strength and modulus at 100% strain was found to increase with increase in the volume fraction of nickel due to reinforcement action. The magnetic impedance and a.c. conductivity are found to increase with increase in volume fraction of nickel as well as frequency.

  17. Electronic and Magnetic Properties of Small Iridium Clusters

    Institute of Scientific and Technical Information of China (English)

    KUANG Xiang-jun

    2004-01-01

    The electronic and magnetic properties of small IrN clusters (N=5, 6, 9, 13, and 19 ) are studied by using the discrete-variational local-spin-density-functional method. The equilibrium bond length in the chosen geometry for IrN clusters are determined and show bond contraction compared with the bulk interatomic spacing. The clusters with magnetic ground state have ferromagnetic interaction and their average magnetic moment per atom has a complex size dependence. At last, the reactivity of IrN clusters toward H2, N2 and CO molecules is predicted.

  18. Evaluating the effect of magnetocaloric properties on magnetic refrigeration performance

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2010-01-01

    on developing materials with a high entropy change with magnetization while placing lower emphasis on the adiabatic temperature change. This work uses model magnetocaloric materials and a numerical AMR model to predict how the temperature change and entropy change with magnetization interact and how they affect......Active magnetic regenerator (AMR) refrigerators represent an alternative to vapor compression technology that relies on the magnetocaloric effect in a solid refrigerant. Magnetocaloric materials are in development and properties are reported regularly. Recently, there has been an emphasis...

  19. Structure and magnetic properties of powder HITPERM material

    Directory of Open Access Journals (Sweden)

    J.E. Frąckowiak

    2007-03-01

    Full Text Available Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based HITPERM amorphous alloy Co68Fe4Mo1Si13.5B13.5 subjected high-energy ball milling and to the isothermal annealing to a combination of these two technologies.Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses ribbons in as state. Using the HFQS program the distributions of the magnetic hyperfine P(H fields were determined for spectra smoothed in this way, employing the Hesse-Rübartsch method. Observations of the structure of powders were made on the OPTON DSM-940 scanning electron microscope. The diffraction examinations and examinations of thin foils were made on the JEOL JEM 200CX transmission electron microscope equipped in equipped with the EDS LINK ISIS X- ray energy dispersive spectrometer made by Oxford. Graphical analyses of the obtained X-ray diffraction patterns, as well as of the HC=f(TA relationship were made using the MICROCAL ORIGIN 6.0 program.Findings: The analysis of the structure and magnetic properties test results of the HITPERM powders alloy Co68Fe4Mo1Si13.5B13.5 obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The magnetic properties of this material and structure and may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment.Research limitations/implications: For the soft magnetic powder material, further magnetical, composition examinations and structure are planed.Practical implications: Feature an alternative to solid alloys are the amorphous and nanocrystalline metal powders obtained by milling of metallic glasses and make it possible to obtain the ferromagnetic nanocomposites, whose dimensions and shape can be freely formed.Originality/value: The paper presents results of influence of parameters

  20. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  1. Magnetic properties of multisegmented cylindrical nanoparticles with alternating magnetic wire and tube segments

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Aravena, D.; Corona, R.M. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Goerlitz, D.; Nielsch, K. [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J., E-mail: jescrigm@gmail.com [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2013-11-15

    The magnetic properties in multisegmented cylindrical nanostructures comprised of nanowire and nanotube segments are investigated numerically as a function of their geometry. In this work we report systematic changes in the coercivity and remanence in these systems. Besides, we have found the ideal conditions for a magnetic configuration with two antiparallel domains that could be used to help to stabilize magnetic nanoparticles inside ferromagnetic multisegmented cylindrical nanoparticles. This magnetic behavior is due to the fact that the tube segment reverses its magnetization before the wire segment, allowing the control of the magnetic domain walls motion between two segments. In this way, these magnetic nanoobjects can be an alternative to store information or even perform logic functions. - Highlights: • Magnetic states of wire/tube were investigated as a function of their geometry. • Multisegmented systems present two well-defined jumps in the hysteresis curve. • It is possible to prepare an antiparallel magnetic configuration. • The step width for the optimum condition reaches 60 mT. • The tube segments reverse their magnetization first than the wire segments.

  2. Preparation, magnetic and electromagnetic properties of organic magnetic prepolymer containing copper phthalocyanine ring

    International Nuclear Information System (INIS)

    A novel kind of organic magnetic prepolymer containing copper phthalocyanine ring was prepared via the polymerization of ferrocenyl organic metal magnetic resin (FOMR) with cuprous chloride. The process of prepolymerization was monitored by Fourier transform infrared spectroscopy and ultraviolet–visible spectrophotometry. Magnetic behavior of the samples was studied by a vibrating sample magnetometer. The experimental results indicated that the organic magnetic prepolymer containing copper phthalocyanine ring showed ferromagnetic property and the magnetism of the samples can be finely tuned by controlling the condition of the reaction. The maximum saturation magnetization of the organic magnetic prepolymer containing copper phthalocyanine ring increased from 3.69 to 8.38 emu/g by increasing the reaction time. Meanwhile, the remnant magnetization increased from 1.06 to 2.36 emu/g. Measurement of electromagnetic parameters of the samples showed that complex permittivity and complex permeability also increased with increase in the reaction time. Among these, the imaginary part of permittivity increased from 0.22 to 0.38 at the frequency of 10.0 GHz. - Highlights: ► A novel organic magnetic prepolymer was successfully prepared. ►The saturation magnetization of samples increased with increase in the reaction time. ► The complex permittivity of samples increased with increase in the reaction time. ► The complex permeability of samples increased with increase in the reaction time. ► The material is believed to be useful in electronic and biomedical fields.

  3. The Mott localization and magnetic properties in condensed fermions systems

    International Nuclear Information System (INIS)

    In the present thesis the Mott localization and magnetic properties in condensed fermions system are considered. The Hubbard model has been used to strongly correlated electron systems and the Skyrme potential to a dense neutron matter with small concentration of protons. A variational approach to the metal-insulator transition is proposed which combines the Mott and Gutzwiller-Brinkman-Rice aspects of the localization. Magnetic properties of strongly correlated electrons are analyzed within the modified spin-rotation-invariant approach in the slow-boson representation. The theoretical prediction for considered systems are presented. 112 refs, 39 figs

  4. Improved Electrical Insulation of Rare Earth Permanent Magnetic Materials With High Magnetic Properties

    Institute of Scientific and Technical Information of China (English)

    CHANG Ying; WANG Da-peng; LI Wei; PAN Wei; YU Xiao-jun; QI Min

    2009-01-01

    Rare earth permanent magnetic materials are typical electrical conductor, and their magnetic properties will decrease because of the eddy current effect, so it is difficult to keep them stable for a long enough time under a high frequency AC field. In the present study, as far as rare earth permanent magnets are concerned, for the first time, rare earth permanent magnets with strong electrical insulation and high magnetic performance have been obtained through experiments, and their properties are as follows:(1) Sm2TM17: Br=0.62 T, jHc=803.7 kA/m, (BH)m= The magnetic properties of Sm2TM17 and NdFeB are obviously higher than those of ferrite permanent magnet, and the electric insulating characteristics of Sm2TM17 and NdFeB applied have in fact been approximately the same as those of ferrite. Therefore, Sm2TM17 and NdFeB will possess the ability to take the place of ferrite under a certain high frequency AC electric field.

  5. Magnetic properties of heat treated bacterial ferrihydrite nanoparticles

    Science.gov (United States)

    Balaev, D. A.; Krasikov, A. A.; Dubrovskiy, A. A.; Popkov, S. I.; Stolyar, S. V.; Bayukov, O. A.; Iskhakov, R. S.; Ladygina, V. P.; Yaroslavtsev, R. N.

    2016-07-01

    The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants KV≈1.7×105 erg/cm3 and KS≈0.055 erg/cm2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed.

  6. Structural, electronic and magnetic properties of MnB2

    Indian Academy of Sciences (India)

    R Masrour; E K Hlil; M Hamedoun; A Benyoussef; O Mounkachi; H El Moussaoui

    2015-08-01

    The self-consistent ab-initio calculations, based on density functional theory approach and using the full potential linear augmented plane wave method, are performed to investigate both electronic and magnetic properties of the MnB2 compounds. Polarized spin and spin–orbit coupling are included in calculations within the framework of the ferromagnetic state between two adjacent Mn atoms. Magnetic moment considered to lie along the (001) axes are computed. The antiferromagnetic and ferromagnetic energies of MnB2 systems are obtained. Obtained data from ab-initio calculations are used as input for the high-temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange interactions between the magnetic atoms Mn–Mn in MnB2 are established by using the mean field theory. The HTSEs of the magnetic susceptibility with the magnetic moments in MnB2 (Mn) through Ising model is given. The critical temperature C (K) is obtained by HTSEs applied to the magnetic susceptibility series combined with the Padé approximant method. The critical exponent associated with the magnetic susceptibility is deduced as well.

  7. Non-Anomalous Semigroups and Real Numbers

    OpenAIRE

    Binder, Damon

    2016-01-01

    Motivated by intuitive properties of physical quantities, the notion of a non-anomalous semigroup is formulated. These are totally ordered semigroups where there are no `infinitesimally close' elements. The real numbers are then defined as the terminal object in a closely related category. From this definition a field structure on $\\mathbb R$ is derived, relating multiplication to morphisms between non-anomalous semigroups.

  8. Measurement of magnetic properties at cryogenic temperatures

    CERN Multimedia

    1977-01-01

    This picture shows part of the low-mu permeameter to measure permeability of stainless steels and other low-mu materials used in superconducting magnets. The sample, a 5 mm diam., 45 mm long rod, is suspended to long leads before being inserted in the test cryostat. For the measurement the sample is surrounded by a flux- measuring coil and placed in the field of a superconducting solenoid. At a given field the sample is removed.During the removal, the voltage induced in the flux-measuring coil is time integrated giving the flux variation. This equipment was developed to select stainless steels and other low-mu materials used in the ISR Prototype Superconducting Qaudrupole. The person is W.Ansorge.

  9. Magnetic properties and magnetic phase diagrams of intermetallic compound GdMn2Ge2

    Institute of Scientific and Technical Information of China (English)

    Guo Guang-Hua(郭光华); Zhang Hai-Bei(张海贝); R.Z.Levitin

    2003-01-01

    A modified Yafet-Kittle model is applied to investigate the magnetic properties and magnetic phase transition of the intermetallic compound GdMn2Ge2.Theoretical analysis and calculation show that there are five possible magnetic structures in GdMn2Ge2.Variations of external magnetic field and temperature give rise to the first-order or secondorder magnetic transitions from one phase to another.Based on this model,the magnetic curves of GdMn2Ge2 single crystals at different temperatures are calculated and a good agreement with experimental data has obtained.Based on the calculation,the H-T magnetic phase diagrams of GdMn2Ge2 are depicted.The Gd-Gd,Gd-Mn,intralayer Mn-Mn and interlayer Mn-Mn exchange coupling parameters are estimated.It is shown that,in order to describe the magnetic properties of GdMn2Ge2,the lattice constant and temperature dependence of interlayer Mn-Mn exchange interaction must be taken into account.

  10. Drug delivery property, bactericidal property and cytocompatibility of magnetic mesoporous bioactive glass

    International Nuclear Information System (INIS)

    A multifunctional magnetic mesoporous bioactive glass (MMBG) has been widely used for a drug delivery system, but its biological properties have been rarely reported. Herein, the effects of mesopores and Fe3O4 nanoparticles on drug loading–release property, bactericidal property and biocompatibility have been investigated by using mesoporous bioactive glass (MBG) and non-mesoporous bioactive glass (NBG) as control samples. Both MMBG and MBG have better drug loading efficiency than NBG because they possess ordered mesoporous channels, big specific surface areas and high pore volumes. As compared with MBG, the Fe3O4 nanoparticles in MMBG not only provide magnetic property, but also improve sustained drug release property. For gentamicin-loaded MMBG (Gent-MMBG), the sustained release of gentamicin and the Fe3O4 nanoparticles minimize bacterial adhesion significantly and prevent biofilm formation against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). Moreover, the magnetic Fe3O4 nanoparticles in MMBG can promote crucial cell functions such as cell adhesion, spreading and proliferation. The excellent biocompatibility and drug delivery property of MMBG suggest that Gent-MMBG has great potentials for treatment of implant-associated infections. - Highlights: • Multifunctional magnetic mesoporous bioactive glass is fabricated. • The bioactive glass has great biocompatibility. • The bioactive glass exhibits high drug loading–release properties. • The drug delivery system has bactericidal property. • Magnetic particles improve cell adhesion, spreading and proliferation

  11. Relation between crystal structure, magnetism and electronic properties in layered ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Johanna; Silex, Anna; Binder, Karsten; Braden, Markus [II. Physikalisches Institut, Univ. Koeln (Germany); Sidis, Yvan; Gukasov, Arsen; Gillon, Beatrice [LLB, Saclay (France); Nakatsuji, Satoru [ISSP, Tokio (Japan); Kikugawa, Naoki; Mackenzie, Andrew [Univ. of St. Andrews (United Kingdom); Nakamura, Fumihiko [ADSM, Hiroshima (Japan)

    2011-07-01

    Layered ruthenates exhibit a close coupling between crystal structure and magnetic and electronic properties, which strengthens the interest in these materials arising from the superconductivity in Sr{sub 2}RuO{sub 4} and Ca{sub 2}RuO{sub 4}. By substituting Sr through isovalent Ca in Ca{sub 2}RuO{sub 4} one tunes the system from the superconductor into a highly anomalous metal with heavy-fermion like properties and finally into an antiferromagnetic Mott insulator. The MIT in Ca{sub 2}RuO{sub 4} can not only be induced by Sr-doping, heating and pressure but also by the application of an electric field. A part of the sample transforms into the metallic phase under the application of moderate electric fields, this phase is characterized by a longer c-lattice parameter and it can be cooled far below room temperature when a finite current density is maintained. At low temperature there is coexistence of the metallic phase and the insulating phase. Doping Ca{sub 3}Ru{sub 2}O{sub 7} with Ti significantly stabilizes a weakly non-metallic phase as seen both in the transition temperature and in the resistivity jump. This effect is especially prominent at a substitution of 10% Ti. A flattening of the lattice is discussed as a general feature accompanying the MIT in layered ruthenates.

  12. Magnetic Properties of Different-Aged Chernozemic Soils

    Science.gov (United States)

    Fattakhova, Leysan; Shinkarev, Alexandr; Kosareva, Lina; Nourgaliev, Danis; Shinkarev, Aleksey; Kondrashina, Yuliya

    2016-04-01

    We investigated the magnetic properties and degree of mineral weathering in profiles of different-aged chernozemic soils derived from a uniform parent material. In this work, layer samples of virgin leached chernozem and chernozemic soils formed on the mound of archaeological earthy monument were used. The characterization of the magnetic properties was carried out on the data of the magnetometry and differential thermomagnetic analysis. The evaluation of the weathering degree was carried out on a loss on ignition, cation exchange capacity and X-ray phase analysis on the data of the original soil samples and samples of the heavy fraction of minerals. It was found that the magnetic susceptibility enhancement in humus profiles of newly formed chernozemic soils lagged significantly behind the organic matter content enhancement. This phenomenon is associated with differences in kinetic parameters of humus formation and structural and compositional transformation of the parent material. It is not enough time of 800-900 years to form a relatively "mature" magnetic profile. These findings are well consistent with the chemical kinetic model (Boyle et al., 2010) linking the formation of the soils magnetic susceptibility with the weathering of primary Fe silicate minerals. Different-aged chernozemic soils are at the first stage of formation of a magnetic profile when it is occur an active production of secondary ferrimagnetic minerals from Fe2+ released by primary minerals.

  13. Microwave Technologies-- Determination of Magnetic and Dielectric Materials Microwave Properties

    OpenAIRE

    Obol, Mahmut

    2009-01-01

    In this study, four different techniques are presented. 1 Rectangular waveguide measurement technique for normal microwave materials microwave properties such as permeability and permittivity. This technique removed guess parameter and dispersive effect issues of the old waveguide measurement techniques. It projects a new route for determination of any microwave materials magnetic and dielectric properties without using any guesses. 2 Coaxial probe measurement technique for the liquid and bio...

  14. Detailed magnetic study on the formato-bridged MOFs with anion-tunable magnetic properties

    Institute of Scientific and Technical Information of China (English)

    WANG XinYi; WANG ZheMing; GAO Song

    2012-01-01

    Detailed studies of the structures,magnetic properties and photodimerization of a series of formato-bridged MOFs with the general formula M2(HCOO)3(4,4'-bpe)3(H20)3(X)(4,4'-bpe =4,4'-bipyridylethylene,M =Mn(l-X-),X- =CIO-4,NO-3,BF-4,I-,Br-; M =Co(2-X-),X- =CIO-4,NO-3; M =Zn(3-X-),X- =NO-3)were reported.Careful magnetic measurements on an oriented single crystal of 1-ClO-4 determined the spin-flop magnetic phase diagram and some intrinsic parameters,such as the intralayer coupling J,the anisotropy field HA and the exchange field HE.Different anions can remarkably tune the magnetic properties of l-X-,especially the critical fields of the spin-flop transition.Compound 2-ClO-4 remained paramagnetic down to 2 K.

  15. Magnetic Properties of Nd8Fe83Co3B6 Nanocomposite Magnets

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The influence of quenching technology, annealing temperature and time on the structures and magnetic properties of Nd8Fe83Co3B6 nanocomposite magnets was investigated. The results show that the α-Fe/Nd2Fe14B nanocomposite magnet containing a small amount of B is difficult to form amorphous state. The magnetic properties of 26 m/s quenched Nd8Fe83Co3B6 powders annealed at 640℃×480 s reach iHc=513 kA/m, Br=1.05 T and (BH)max=92.0 kJ/m3. The grain size is Dα-Fe=21.5 nm and DNd2Fe14B=30.2 nm.

  16. Surface properties and fatigue limit of metal. Comminication 3. Model of fatigue for metal failure with regard for anomalous properties of surface layer. Scale effect. Residual stresses

    International Nuclear Information System (INIS)

    The obtained data on the anomalous decrease of the yield point near the material surface with regard for characteristics of cyclic crack resistance are used to formulate a model of fatigue material failure. The model permits calculating a fatigue limit either of a specimen or of a construction according to a noncritical nonpropagating crack under bending, tension-compression for objects of different thickness and shape with notches of different depth with the presence of residual stresses and loading cycle asymmetry

  17. Magnetic properties of a long, thin-walled ferromagnetic nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chen, E-mail: chen.sun@physics.tamu.edu [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Pokrovsky, Valery L. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Landau Institute for Theoretical Physics, Chernogolovka, Moscow District, 142432 (Russian Federation)

    2014-04-15

    We consider magnetic properties of a long, thin-walled ferromagnetic nanotube. We assume that the tube consists of isotropic homogeneous magnet whose spins interact via the exchange energy, the dipole–dipole interaction energy, and also interact with an external field via Zeeman energy. Possible stable states are the parallel state with the magnetization along the axis of the tube, and the vortex state with the magnetization along azimuthal direction. For a given material, which of them has lower energy depends on the value γ=R{sup 2}d/(Lλ{sub x}{sup 2}), where R is the radius of the tube, d is its thickness, L is its length and λ{sub x} is an intrinsic scale of length characterizing the ratio of exchange and dipolar interaction. At γ<1, the parallel state wins, otherwise the vortex state is stable. A domain wall in the middle of the tube is always energy unfavorable, but it can exist as a metastable structure. Near the ends of a tube magnetized parallel to the axis a half-domain structure transforming gradually the parallel magnetization to a vortex just at the edge of the tube is energy favorable. We also consider the equilibrium magnetization textures in an external magnetic field either parallel or perpendicular to the tube. Finally, magnetic field produced by a nanotube and an array of tubes is analyzed. - Highlights: • We obtain a simple criterion for stable state of a long, thin-walled magnetic tube. • A domain wall in the middle is always energy unfavorable, but can be metastable. • In external field different states show different hystereses. • Field produced by a tube and an array of tubes is calculated.

  18. Synthesis and properties of magnetic ceramic nanoparticles

    Science.gov (United States)

    Sorescu, Monica

    2012-02-01

    Magnetic ceramic nanoparticles of the type xIn2O3-(1-x)alpha-Fe2O3, xV2O5-(1-x)alpha-Fe2O3 and xZnO-(1-x)alpha-Fe2O3 (x=0.1-0.7) were synthesized from the mixed oxides using mechanochemical activation for 0-12 hours. X-ray diffraction was used to derive the phase content, lattice constants and particle size information as function of ball milling time. Mossbauer spectroscopy results correlated with In3+, V5+ and Zn2+ substitution of Fe3+ in the hematite lattice. SEM/EDS measurements revealed that the mechanochemical activation by ball milling produced systems with a wide range of particle size distribution, from nanometer particles to micrometer agglomerates, but with a uniform distribution of the elements. Simultaneous DSC-TGA investigations up to 800 degrees C provided information on the heat flow, weight loss and the enthalpy of transformation in the systems under investigation. This study demonstrates the formation of a nanostructured solid solution for the indium oxide, an iron vanadate (FeVO4) for the vanadium oxide, and of the zinc ferrite (ZnFe2O4) for the zinc oxide. The transformation pathway for each case can be related to the oxidation state of the metallic specie of the oxide used in connection with hematite.

  19. Preparation and Properties of Various Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jaromir Hubalek

    2009-03-01

    Full Text Available The fabrications of iron oxides nanoparticles using co-precipitation and gadolinium nanoparticles using water in oil microemulsion method are reported in this paper. Results of detailed phase analysis by XRD and Mössbauer spectroscopy are discussed. XRD analysis revealed that the crystallite size (mean coherence length of iron oxides (mainly γ-Fe2O3 in the Fe2O3 sample was 30 nm, while in Fe2O3/SiO2 where the ε-Fe2O3 phase dominated it was only 14 nm. Gd/SiO2 nanoparticles were found to be completely amorphous, according to XRD. The samples showed various shapes of hysteresis loops and different coercivities. Differences in the saturation magnetization (MS correspond to the chemical and phase composition of the sample materials. However, we observed that MS was not reached in the case of Fe2O3/SiO2, while for Gd/SiO2 sample the MS value was extremely low. Therefore we conclude that only unmodified Fe2O3 nanoparticles are suitable for intended biosensing application in vitro (e.g. detection of viral nucleic acids and the phase purification of this sample for this purpose is not necessary.

  20. Neutron investigations of magnetic properties of crystal substances with use of a pulsed magnetic field

    CERN Document Server

    Nitts, V V

    2001-01-01

    Bases for neutron researches of magnetic properties of crystal substances with use of a pulsed magnetic field and analysis of possible application of various neutron sources in this area are submitted. The review of the most interesting physical results is presented. Main investigations on pulsed reactors of JINR are researches on kinetics of the first order reorientational phase transitions induced in single crystals, and also measurements of antiferromagnetic ordering induced by an external magnetic field. Magnetic phase transitions, induced by a field up to 160 kOe in several magnetic ordering substances, were studied in KEK (Japan). Experiment on observation of spin-flop transition in MnF sub 2 was carried out on TRIGA-reactor in a mode of single flashes of power

  1. Electronic Structure and Magnetic Properties of Cobalt Doped Zinc Oxide

    Directory of Open Access Journals (Sweden)

    O.U. Okeke

    2011-01-01

    Full Text Available Using the first principle methods, the electronic structure and magnetic properties of Co doped ZnO are investigated. It is found that Co substitutes Zn site in the host, and this doped configuration favors the ferromagnetic ground state. Electronic structure calculation shows that total magnetic moment for the supercell is 3.03 µB, which is mainly, contributed by Dopant (Co 2.45 µB. The compound is found to be a semiconductor, where the filled-states are located in the valence bands and the empty ones above the conduction band edge. The filled and empty d-states are also shown to shift downwards and upwards in the valence and the conduction bands, respectively. The total and atom resolved density of states shed light on the evolution of the electronic and magnetic properties.

  2. Surface modification of Fe304 nanoparticles and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    Hao Yan; Jian-cheng Zhang; Chen-xia You; Zhen-wei Song; Ben-wei Yu; Yue Shen

    2009-01-01

    Fe3O4 magnetic nanoparticles were synthesized by the hydrothermal method, and the influences of the surfactant sodium bis(2-ethylhexyl) sulfosuecinate (AOT) on the particles were investigated. The structure, morphology, and magnetic properties of the products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). It is confirmed that the as-prepared nanopartieles have been modified by using the surfactant during the synthesis process. The amount of the surfactant has an effect on the size, the dispersal, and the magnetic properties of the particles. Besides, the mechanisms of the influences were also discussed.

  3. Transport properties of graphene under periodic and quasiperiodic magnetic superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Tao, E-mail: luweitao@lyu.edu.cn [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Wang, Shun-Jin [Department of Physics, Sichuan University, 610064 Chengdu (China); Wang, Yong-Long; Jiang, Hua [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Li, Wen [School of Science, Linyi University, 276005 Linyi (China)

    2013-08-15

    We study the transmission of Dirac electrons through the one-dimensional periodic, Fibonacci, and Thue–Morse magnetic superlattices (MS), which can be realized by two different magnetic blocks arranged in certain sequences in graphene. The numerical results show that the transmission as a function of incident energy presents regular resonance splitting effect in periodic MS due to the split energy spectrum. For the quasiperiodic MS with more layers, they exhibit rich transmission patterns. In particular, the transmission in Fibonacci MS presents scaling property and fragmented behavior with self-similarity, while the transmission in Thue–Morse MS presents more perfect resonant peaks which are related to the completely transparent states. Furthermore, these interesting properties are robust against the profile of MS, but dependent on the magnetic structure parameters and the transverse wave vector.

  4. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    International Nuclear Information System (INIS)

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer’s sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10−8 Am2 was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample

  5. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, J. F. D. F.; Bruno, A. C.; Louro, S. R. W. [Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro 22451-900 (Brazil)

    2015-10-15

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer’s sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10{sup −8} Am{sup 2} was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  6. Gd doped Au nanoclusters: Molecular magnets with novel properties

    KAUST Repository

    Mokkath, Junais Habeeb

    2014-01-01

    The structural, magnetic, and optical properties of subnanometer Au N and AuN-1Gd1 gas phase clusters (N = 2 to 8) are systematically investigated in the framework of (time-dependent) density functional theory, using the B3LYP hybrid exchange correlation functional. The size dependent evolution of the gap between the highest occupied and lowest unoccupied molecular orbitals, the magnetism, and the absorption spectra are studied. The simultaneous appearance of large magnetic moments, significant band gaps, and plasmon resonances in the visible spectral region leads to novel multi-functional nanomaterials for applications in drug delivery, magnetic resonance imaging, and photo-responsive agents. © 2013 Elsevier B.V. All rights reserved.

  7. Magnetic properties of Fe/NiO/Fe(001) trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Biagioni, P. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: paolo.biagioni@polimi.it; Brambilla, A. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Portalupi, M. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Rougemaille, N. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Schmid, A.K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lanzara, A. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Physics, University of California at Berkeley, Berkeley, CA 94720 (United States); Vavassori, P. [INFM - Dipartimento di Fisica, Universita di Ferrara, Via Paradiso 12, 44100 Ferrara (Italy); Zani, M. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Finazzi, M. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Duo, L. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Ciccacci, F. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)

    2005-04-15

    We have investigated the magnetic properties of epitaxially grown Fe/NiO/Fe(001) trilayers, for different thicknesses of the NiO spacer. Magneto Optical Kerr Effect has been exploited to study the in-plane magnetization reversal processes in the iron layers. We found that the NiO thickness t{sub AFM} has a critical value t{sub C} for the magnetic coupling between the Fe layers: for t{sub AFM}magnetization directions align perpendicularly, with zero applied field, while the alignment is collinear for thicker spacers. A phenomenological model has been developed to reproduce and discuss the results. Complementary information has been obtained by means of spin polarized low energy electron microscopy.

  8. On magnetic properties of superparamagnets in the Curie point region

    CERN Document Server

    Nikolaev, V I; Eng-Chan, K

    2000-01-01

    The features of the paraprocess in superparamagnetic particles in the Curie point region are discussed. To describe the dependencies of the magnetic properties of superparamagnetic particles on temperature and field, the molecular field theory supplemented with the Langevin model is applied. It is shown that, as in the case of ordinary ferromagnetic particles, the paraprocess in superparamagnetic particles in the region of small fields is determined by the dominant influence of the exchange field inside the particle. The role of the external field is, mainly, to change (or even to give rise to) the exchange field. However, the quantitative characteristics describing the paraprocess in a superparamagnet are completely different. The magnetic susceptibility of the paraprocess chi sub M (M being the specific magnetization of the particle corresponding to its 'relaxation' magnetic moment mu in the field H) at the Curie temperature is independent of the field strength. Under the same conditions, the 'experimentall...

  9. Electromagnetic fields and anomalous transports in heavy-ion collisions --- A pedagogical review

    CERN Document Server

    Huang, Xu-Guang

    2015-01-01

    The hot and dense matter generated in heavy-ion collisions may contain domains in which the P and CP symmetries of QCD are violated. Moreover, heavy-ion collisions can generate extremely strong magnetic fields as well as electric fields. The interplay among the electromagnetic field, triangle anomaly, and the P and CP violation of QCD leads to a number of macroscopic quantum phenomena known as the anomalous transports. The purpose of the article is to give a pedagogical review of various properties of the electromagnetic fields, the anomalous transports phenomena, and their experimental signatures in heavy-ion collisions.

  10. Electromagnetic fields and anomalous transports in heavy-ion collisions—a pedagogical review

    Science.gov (United States)

    Huang, Xu-Guang

    2016-07-01

    The hot and dense matter generated in heavy-ion collisions may contain domains which are not invariant under P and CP transformations. Moreover, heavy-ion collisions can generate extremely strong magnetic fields as well as electric fields. The interplay between the electromagnetic field and triangle anomaly leads to a number of macroscopic quantum phenomena in these P- and CP-odd domains known as anomalous transports. The purpose of this article is to give a pedagogical review of various properties of the electromagnetic fields, the anomalous transport phenomena, and their experimental signatures in heavy-ion collisions.

  11. Defects, phase transformations and magnetic properties of lithium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, R.K.

    1977-03-01

    Achieving suitable magnetic properties in ceramic ferrites through thermomechanical treatments rather than through varying the processing and fabrication parameters alone has been investigated. Ferrimagnetic lithium ferrite and some other spinel structure materials were chosen for this investigation. Extensive characterization of phase transformations and lattice defects was done.

  12. Magnetic Properties of Nd-Group V Compounds

    DEFF Research Database (Denmark)

    Bak, Poul Erik; Lindgård, Per-Anker

    1973-01-01

    The Nd monopnictides NdP, NdAs and NdSb are simple cubic type I antiferromagnets in which the crystal-field splitting is larger than the exchange energy. The magnetic properties are calculated by means of a mean-field theory including crystal-field and magnetoelastic effects. The calculations are...

  13. Magnetic and ferroelectric properties of multiferroic RMn2O5

    Science.gov (United States)

    Noda, Y.; Kimura, H.; Fukunaga, M.; Kobayashi, S.; Kagomiya, I.; Kohn, K.

    2008-10-01

    The magnetic and ferroelectric properties of multiferroic RMn2O5 (R = Y, Tb, Ho, Er, Tm) are reviewed based on recent neutron diffraction and dielectric measurements. Successive phase transitions of magnetic and dielectric ordering were found to occur simultaneously in this system. The characteristic magnetic ordering of the system exhibits an incommensurate-commensurate phase transition, and again transitions to an incommensurate phase. Special attention is given to the magnetic structure in order to discuss the mechanism for the introduction of ferroelectric polarization. For all the compounds examined, the spin configuration for Mn4+ and Mn3+ ions in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. By contrast, the alignment of the induced 4f moment of R3+ ions showed variation, depending on the character of each of the elements. Corresponding responses to external fields such as a magnetic field, hydrostatic pressure etc at low temperature are strongly dependent on the rare earth element present in the RMn2O5 system. The so-called colossal magnetoelectric effect in this system can be easily interpreted by the phase transition from the magnetic incommensurate and weak ferroelectric phase to the commensurate and ferroelectric phase.

  14. Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes.

    Science.gov (United States)

    Felicia, Leona J; Philip, John

    2014-02-01

    We investigate the effect of multiwalled carbon nanotubes (MWCNTs) on the magnetorheological properties of an oil based magnetic nanofluid (ferrofluid). The shear resistant plateau observed in a pure ferrofluid disappears when 0.5 wt% of MWCNT is incorporated. The yield stress values of the composite system are slightly smaller than that of the pure system. This shows that the presence of carbon nanotubes (CNTs) weakens the magnetic field induced microstructure of the ferrofluid due to their interaction that affects the hydrodynamic and magnetic interactions between the dispersed nanoparticles. Interestingly, the Mason number plots for both the pure and composite system show scaling of the viscosity curves onto a single master curve for magnetic fields of 80 mT and above while deviations are observed for lower magnetic fields. The weakening of the ferrofluid microstructure in the presence of CNTs is further evident in the amplitude sweep measurements where the linear viscoelastic region develops only at a higher magnetic field strength compared to lower magnetic fields in pure ferrofluids. These results are useful for tailoring ferrofluids with a faster response for various applications. PMID:25353475

  15. Properties of mesons in a strong magnetic field

    Science.gov (United States)

    Zhang, Rui; Fu, Wei-jie; Liu, Yu-xin

    2016-06-01

    By extending the Φ -derivable approach in the Nambu-Jona-Lasinio model to a finite magnetic field we calculate the properties of pion, σ , and ρ mesons in a magnetic field at finite temperature not only in the quark-antiquark bound state scheme but also in the pion-pion scattering resonant state scenario. Our calculation as a result makes manifest that the masses of π 0 and σ meson can be nearly degenerate at the pseudo-critical temperature which increases with increasing magnetic field strength, and the π ^{± } mass ascends suddenly at almost the same critical temperature. Meanwhile the ρ mesons' masses decrease with the temperature but increase with the magnetic field strength. We also check the Gell-Mann-Oakes-Renner relation and find that the relation can be violated clearly with increasing temperature, and the effect of the magnetic field becomes pronounced around the critical temperature. With different criteria, we analyze the effect of the magnetic field on the chiral phase transition and find that the pseudo-critical temperature of the chiral phase cross, T_c^{χ }, is always enhanced by the magnetic field. Moreover, our calculations indicate that the ρ mesons will get melted as the chiral symmetry has not yet been restored, but the σ meson does not disassociate even at very high temperature. Particularly, it is the first to show that there does not exist a vector meson condensate in the QCD vacuum in the pion-pion scattering scheme.

  16. Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes

    Science.gov (United States)

    Felicia, Leona J.; Philip, John

    2014-02-01

    We investigate the effect of multiwalled carbon nanotubes (MWCNTs) on the magnetorheological properties of an oil based magnetic nanofluid (ferrofluid). The shear resistant plateau observed in a pure ferrofluid disappears when 0.5 wt % of MWCNT is incorporated. The yield stress values of the composite system are slightly smaller than that of the pure system. This shows that the presence of carbon nanotubes (CNTs) weakens the magnetic field induced microstructure of the ferrofluid due to their interaction that affects the hydrodynamic and magnetic interactions between the dispersed nanoparticles. Interestingly, the Mason number plots for both the pure and composite system show scaling of the viscosity curves onto a single master curve for magnetic fields of 80 mT and above while deviations are observed for lower magnetic fields. The weakening of the ferrofluid microstructure in the presence of CNTs is further evident in the amplitude sweep measurements where the linear viscoelastic region develops only at a higher magnetic field strength compared to lower magnetic fields in pure ferrofluids. These results are useful for tailoring ferrofluids with a faster response for various applications.

  17. Magnetic properties of nanocrystalline cobalt based powder soft magnetic materials and nanocomposites with silicon matrix

    International Nuclear Information System (INIS)

    The paper presents the effect of the high energy ball milling parameters and of isothermal heating of the cobalt based metallic glasses on the magnetic properties and structure of the powder material and silicon matrix nano-composites. The high energy ball milling process of the Co68Fe4Mo1Si13.5B13.5 metallic glass was carried out for various time period in the 'as quenched' state and after the isothermal heating. Heating of powder obtained by milling was also performed, to check its effect on changes of magnetic properties. The effects of the high energy ball milling and isothermal heating on the structure, grain size and magnetic properties of powder, and of the silicon base nano-composites made from them were also investigated. (author)

  18. Surface magnetism Correlation of structural, electronic and chemical properties with magnetic behavior

    CERN Document Server

    Getzlaff, Mathias

    2010-01-01

    This volume reviews on selected aspects related to surface magnetism, a field of extraordinary interest during the last decade. The special emphasis is set to the correlation of structural, electronic and magnetic properties in rare earth metal systems and ferromagnetic transition metals. This is made possible by the combination of electron emission techniques (spin polarized photoelectron spectroscopy, magnetic dichroism in photoemission and spin polarized metastable deexcitation spectroscopy) and local probes with high lateral resolution down to the atomic scale (spin polarized scanning tunneling microscopy / spectroscopy).

  19. Spectrum of anomalous magnetohydrodynamics

    Science.gov (United States)

    Giovannini, Massimo

    2016-05-01

    The equations of anomalous magnetohydrodynamics describe an Abelian plasma where conduction and chiral currents are simultaneously present and constrained by the second law of thermodynamics. At high frequencies the magnetic currents play the leading role, and the spectrum is dominated by two-fluid effects. The system behaves instead as a single fluid in the low-frequency regime where the vortical currents induce potentially large hypermagnetic fields. After deriving the physical solutions of the generalized Appleton-Hartree equation, the corresponding dispersion relations are scrutinized and compared with the results valid for cold plasmas. Hypermagnetic knots and fluid vortices can be concurrently present at very low frequencies and suggest a qualitatively different dynamics of the hydromagnetic nonlinearities.

  20. Synthesis, morphology, microstructure and magnetic properties of hematite submicron particles

    Energy Technology Data Exchange (ETDEWEB)

    Tadic, Marin, E-mail: marint@vinca.rs [Condensed Matter Physics Laboratory, Vinca Institute, University of Belgrade, POB 522, 11001 Belgrade (Serbia); Citakovic, Nada [Military Academy, Generala Pavla Jurisica Sturma 33, 11000 Belgrade (Serbia); Panjan, Matjaz [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Stojanovic, Zoran [Institute of Technical Sciences, Serbian Academy of Arts and Sciences, Knez Mihajlova 35/IV, 11000 Belgrade (Serbia); Markovic, Dragana; Spasojevic, Vojislav [Condensed Matter Physics Laboratory, Vinca Institute, University of Belgrade, POB 522, 11001 Belgrade (Serbia)

    2011-07-14

    Graphical abstract: Highlights: > Plate-like hematite {alpha}-Fe{sub 2}O{sub 3} particles were prepared by template-free hydrothermal route. > The micrographs show a width of the plate-like particles of {approx}500 nm and a thickness of {approx}100 nm (aspect ratio {approx} 5). > The HRTEM shows perfect lattice fringes and preferring crystal growth along [0 1 2] direction. > The values of the coercivity, remanent magnetization and saturation magnetization at room temperature are H{sub C} = 1140 Oe, M{sub r} = 0.125 emu/g and M{sub S} = 2.15 emu/g, respectively. > The Morin temperature is observed at T{sub M} {approx} 250 K. - Abstract: We report on hydrothermal synthesis, plate-like morphology, microstructure and magnetic properties of hematite ({alpha}-Fe{sub 2}O{sub 3}) plate-like particles. The sample is obtained immediately after the hydrothermal process without using any template and without further heat treatment. The so-obtained sample is characterized by X-ray powder diffraction (XRPD), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and superconducting quantum interference device (SQUID) magnetometer. XRPD confirms the formation of a single-phase hematite sample whereas EDX reveals that iron and oxygen are the only components of the sample. SEM, FE-SEM, TEM and HRTEM show that the sample is composed of plate-like particles. The width of the particles is {approx}500 nm whereas thickness is {approx}100 nm (aspect ratio 5:1). The HRTEM images exhibit well defined lattice fringes of {alpha}-Fe{sub 2}O{sub 3} particles that confirm their high crystallinity. Moreover, the HRTEM analysis indicates the plate-like particles preferring crystal growth along [0 1 2] direction. Magnetic measurements display significant hysteretic behavior at room temperature with coercivity H{sub C} = 1140 Oe, remanent magnetization M{sub r} = 0.125 emu/g and

  1. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals

    OpenAIRE

    Wang, Xiang; Pu, Shengli; Ji, Hongzhu; YU, GUOJUN

    2012-01-01

    Ferronematic materials composed of 4-cyano-4′-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to ...

  2. The charmonium dissociation in an "anomalous wind"

    CERN Document Server

    Sadofyev, Andrey V

    2016-01-01

    We study the charmonium dissociation in a strongly coupled chiral plasma in the presence of magnetic field and axial charge imbalance. This type of plasma carries ``anomalous flow" induced by the chiral anomaly and exhibits novel transport phenomena such as chiral magnetic effect. We found that the ``anomalous flow" would modify the charmonium color screening length by using the gauge/gravity correspondence. We derive an analytical expression quantifying the ``anomalous flow" experienced by a charmonium for a large class of chiral plasma with a gravity dual. We elaborate on the similarity and {\\it qualitative} difference between anomalous effects on the charmonium color screening length which are {\\it model-dependent} and those on the heavy quark drag force which are fixed by the second law of thermodynamics. We speculate on the possible charmonium dissociation induced by chiral anomaly in heavy ion collisions.

  3. Anomalous transport equations in toroidal plasmas

    International Nuclear Information System (INIS)

    Reduced transport equations for a toroidal plasma with fluctuations are derived. These equations include the effects of both anomalous and standard neoclassical transport, and allow clarification of the structure of convective fluxes caused by electrostatic and magnetic fluctuations. Special attention is paid to the combined effects of fluctuations and toroidicity on the transport. The formulation retains the effects of a magnetic field inhomogeneity on the anomalous transport. It is shown that phase space diffusion caused by the gradient in the equilibrium magnetic field appears as a pinch flux in the real space

  4. Anomalous Hall effect for semiclassical chiral fermions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengming, E-mail: zhpm@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China); Horváthy, P.A., E-mail: horvathy@lmpt.univ-tours.fr [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China); Laboratoire de Mathématiques et de Physique Théorique, Université de Tours (France)

    2015-03-06

    Semiclassical chiral fermions manifest the anomalous spin-Hall effect: when put into a pure electric field they suffer a side jump, analogous to what happens to their massive counterparts in non-commutative mechanics. The transverse shift is consistent with the conservation of the angular momentum. In a pure magnetic field, instead, spiraling motion is found. Motion in Hall-type perpendicular electric and magnetic fields is also studied. - Highlights: • Chiral fermions exhibit an anomalous spin-Hall effect. • Transverse shift appears in a pure electric field. • In a pure magnetic field spiraling motion is found.

  5. Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

    Institute of Scientific and Technical Information of China (English)

    姜忠良; 陈秀云; 陈晓东; 石大立; 杨昌平; 朱静

    2002-01-01

    The effect of Hydrogen Decrepitation (HD) process on the magnetic properties and microstructure of sintered NdFeAlB magnet (HD magnet) was investigated. The results show that the coercivity of HD magnet is higher than that of traditional ball milling (BM) magnet, while the remanence and the maximum energy product of HD magnet are lower. Microstructure analysis shows that some fine un-sintered powders are distributed at the grain boundaries of HD magnet. X-ray diffraction (XRD) analysis reveals that the degree of easy axis alignment of HD magnet is lower. Some ideas to improve the current HD process were proposed.

  6. Effects of oxygen and carbon on the magnetic properties and microstructure of Sm2Co17 permanent magnets

    Institute of Scientific and Technical Information of China (English)

    TIAN Jianjun; ZHANG Shengen; QU Xuanhui

    2007-01-01

    The research on the sintered Sm2Co17 permanent magnets prepared by metal injection molding is still at the exploratory stage. Carbon and oxygen are two key factors that influence the magnetic properties. In this article, the effects of oxygen and carbon on the properties and microstructure of the magnets have been studied. The results indicate that oxygen consumes the effective Sm content of the magnets and forms Sm2O3-the non-magnetism phase, which result in the deterioration of the magnetic properties. Besides, the magnetic properties decrease in evidence with increasing carbon content. The main factor that affects the magnetic properties is the deterioration of the microstructure of the magnets. The Sm(Co, Cu)5 phase decreases, whereas the cell size increases with the increase of the carbon content. When the carbon content is above 0.43 wt.%, the Sm(Co, Cu)5 phase is not enough to form a uniform cellular microstructure. Thus the magnetic properties disappear. ZrC is detected in the magnets by XRD when the carbon content is above 0.21 wt.%. ZrC also reduces the properties of the magnets.

  7. Magnetic properties of lanthanoid(III) phthalocyaninato triple-decker complexes in an external magnetic field and electronic transport properties for molecular spintronics

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, K; Yamamoto, K; Breedlove, B K; Yamashita, M [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578 (Japan); Kajiwara, T [Department of Chemistry, Faculty of Science, Nara Women' s University, Nishi-Machi, Kita-Uoya, Nara 630-8506 (Japan); Takeya, J, E-mail: yamashita@agnus.chem.tohoku.ac.jp [Institute of Scientific and Industrial Research, Osaka University, Mihogaoka, Ibaragi 567-0047 (Japan)

    2011-07-06

    Lanthanoid phthalocyaninato complexes of Dy{sub 2}(obPc){sub 3} (1) and Tb{sub 2}(obPc){sub 3} (2) are shown to be a single-molecule magnet. The relationships among the magnetic relaxation properties of 1 in a direct current (dc) magnetic field in comparison to 2 and the electronic properties of a cast film are discussed.

  8. Magnetic antenna excitation of whistler modes. I. Basic properties

    Energy Technology Data Exchange (ETDEWEB)

    Urrutia, J. M.; Stenzel, R. L. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2014-12-15

    Properties of magnetic loop antennas for exciting electron whistler modes have been investigated in a large laboratory plasma. The parameter regime is that of large plasma frequency compared to the cyclotron frequency and signal frequency below half the cyclotron frequency. The antenna diameter is smaller than the wavelength. Different directions of the loop antenna relative to the background magnetic field have been measured for small amplitude waves. The differences in the topology of the wave magnetic field are shown from measurements of the three field components in three spatial directions. The helicity of the wave magnetic field and of the hodogram of the magnetic vector in space and time are clarified. The superposition of wave fields is used to investigate the properties of two antennas for small amplitude waves. Standing whistler waves are produced by propagating two wave packets in opposite directions. Directional radiation is obtained with two phased loops separated by a quarter wavelength. Rotating antenna fields, produced with phased orthogonal loops at the same location, do not produce directionality. The concept of superposition is extended in a Paper II to generate antenna arrays for whistlers. These produce nearly plane waves, whose propagation angle can be varied by the phase shifting the currents in the array elements. Focusing of whistlers is possible. These results are important for designing antennas on spacecraft or diagnosing and heating of laboratory plasmas.

  9. Synthesis and magnetic properties of tin spinel ferrites doped manganese

    Science.gov (United States)

    El Moussaoui, H.; Mahfoud, T.; Habouti, S.; El Maalam, K.; Ben Ali, M.; Hamedoun, M.; Mounkachi, O.; Masrour, R.; Hlil, E. K.; Benyoussef, A.

    2016-05-01

    In this work we report the synthesis, the microstructural characterization and the magnetic properties of tin spinel ferrites doped manganese (Sn1-xMnxFe2O4 with x=0.25, 0.5, 0.75, and 1) nanoparticles prepared by co-precipitation method. The effect of annealing temperature on the structure, morphology and magnetic properties of Sn0.5Mn0.5Fe2O4 has been investigated. The synthesized nanoparticle sizes have been controlled between 4 and 9 nm, with uniform spherical morphology as confirmed by transmission electron microscopy (TEM). All the samples prepared possess single domain magnetic. The nanoparticles of Sn0.5Mn0.5Fe2O4 with 4 nm in diameter have a blocking temperature close to 100 K. In addition, the cation distribution obtained from the X-ray diffraction of this sample was confirmed by magnetic measurement. For the Sn1-xMnxFe2O4; (0≤x≤1) samples, the magnetization and coercive fields increase when the augmentation of Mn content increases. For x=0.5, such parameters decrease when the calcination temperature increases.

  10. Thermodynamic properties of magnetic strings on a square lattice

    Science.gov (United States)

    Mol, Lucas; Oliveira, Denis Da Mata; Bachmann, Michael

    2015-03-01

    In the last years, spin ice systems have increasingly attracted attention by the scientific community, mainly due to the appearance of collective excitations that behave as magnetic monopole like particles. In these systems, geometrical frustration induces the appearance of degenerated ground states characterized by a local energy minimization rule, the ice rule. Violations of this rule were shown to behave like magnetic monopoles connected by a string of dipoles that carries the magnetic flux from one monopole to the other. In order to obtain a deeper knowledge about the behavior of these excitations we study the thermodynamics of a kind of magnetic polymer formed by a chain of magnetic dipoles in a square lattice. This system is expected to capture the main properties of monopole-string excitations in the artificial square spin ice. It has been found recently that in this geometry the monopoles are confined, but the effective string tension is reduced by entropic effects. To obtain the thermodynamic properties of the strings we have exactly enumerated all possible string configurations of a given length and used standard statistical mechanics analysis to calculate thermodynamic quantities. We show that the low-temperature behavior is governed by strings that satisfy ice rules. Financial support from FAPEMIG and CNPq (Brazilian agencies) are gratefully acknowledged.

  11. Low-frequency acoustic and electric properties of PbFe1/2Nb1/2O3 and PbFe2/3W1/3O3 ceramics with magnetic ordering

    International Nuclear Information System (INIS)

    The elastic, inelastic and dielectric properties of ceramics with magnetic ordering PbFe1/2Nb1/2O3 and PbFe2/3W1/3O3 in the range of temperatures including the Curie and Neel points, were studied. A correlation in the behavior of elastic and dielectric properties of the compounds studied in the range of blurred ferroelectric phase transition was established. Anomalous change in the modulus of elasticity and internal friction around the Neel temperature was detected, which stems from magnetostriction bond between deformation and magnetic ordering parameter

  12. Anomalous transport due to scale anomaly

    CERN Document Server

    Chernodub, M N

    2016-01-01

    We show that the scale anomaly in field theories leads to new anomalous transport effects that emerge in external electromagnetic field in inhomogeneous gravitational background. In inflating geometry the QED scale anomaly generates electric current which flows in opposite direction with respect to background electric field. In static spatially inhomogeneous gravitational background the dissipationless electric current flows transversely both to the magnetic field axis and to the gradient of the inhomogeneity. The anomalous currents are proportional to the beta function of the theory.

  13. GEMAS: Mineral magnetic properties of European agricultural soils

    Science.gov (United States)

    Kuzina, Dilyara; Kosareva, Lina; Fattakhova, Leysan; Fabian, Karl; Nourgaliev, Danis; Reimann, Clemens

    2015-04-01

    The GEMAS survey of European agricultural soil provides a unique opportunity to create the first comprehensive overview of mineral magnetic properties in agricultural soil on a continental scale. Samples from the upper 20 cm were taken in large agricultural fields (Ap-sample) at a density of 1 site/2500 km2. After air drying and sieving to characterizing the individual soil samples, the new data allow to study magnetic parameters in relation to chemical and geological parameters. The results show a clear large scale spatial distribution with e.g. broad distinct lows of k over sandy sediments of the last glaciation in central northern Europe and other sedimentary basins. More localized positive k anomalies occur near young volcanism, or old basalts exposed on the surface. On the other hand, frequency dependence of k displays a much more scattered behavior, indicating either high noise level, or large local variability. Clearly distinguishable, small-scale patterns in the randomized data set indicate that the latter is more likely. This indicates that local influences on soil magnetic properties, including anthropogenic effects, may be easier detected by frequency dependence than by k itself, which is largely controlled by geological and climatic background variability. Mapping the isothermal mineral magnetic properties shows again a clear relation to large scale European geology. Thereby, the GEMAS data set of magnetic parameters provides a continent wide reference of the natural background in Ap soil. For the first time the geological background variability of magnetic minerals for national and local soil studies is defined at the European scale.

  14. Modification of magnetic properties of polyethyleneterephthalate by iron ion implantation

    International Nuclear Information System (INIS)

    Fe+ ions (40 keV) were implanted into polyethyleneterephthalate (PET) films with fluences of (0.25-1.5) x 1017 cm-2. Magnetic properties of the synthesised Fe:PET composites were studied using superconducting quantum interference device (SQUID) technique in temperature range of 2-300 K. For range of fluences (0.5-0.75) x 1017 cm-2 the samples reveal superparamagnetic behaviour at room temperature. At fluences above 0.75 x 1017 cm-2 the strong increase of magnetisation and transition to ferromagnetic properties are registered. Analysis of the magnetic hysteresis loops suggests an easy plane magnetic anisotropy similar to that found for thin magnetic films. Zero-field-cooled (ZFC) and field-cooled (FC) temperature measurements of magnetisation are found to be in agreement with earlier observed formation of Fe nanoparticles (NPs) in the implanted layers. The growth and agglomeration of the NPs forming the quasi-continuous labyrinth-like structure in the polymer film at the highest implantation fluence of 1.5 x 1017 cm-2 is an origin for the transition to the ferromagnetic properties

  15. Modification of magnetic properties of polyethyleneterephthalate by iron ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Lukashevich, M.G. [Belarusian State University, Independence Avenue 4, 22050 Minsk (Belarus); Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia, Universitat de Barcelona, Avenue Diagonal 647, 08028 Barcelona (Spain); Batlle, X. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia, Universitat de Barcelona, Avenue Diagonal 647, 08028 Barcelona (Spain); Labarta, A. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia, Universitat de Barcelona, Avenue Diagonal 647, 08028 Barcelona (Spain); Popok, V.N. [Department of Physics, Goeteborg University, Goeteborg 41296 (Sweden)]. E-mail: popok@physics.gu.se; Zhikharev, V.A. [Kazan State Technology University, K. Marks Street 68, 420015 Kazan (Russian Federation); Kazan Physical-Technical Institute, Sibirsky Trakt 10/7, 420029 Kazan (Russian Federation); Khaibullin, R.I. [Kazan Physical-Technical Institute, Sibirsky Trakt 10/7, 420029 Kazan (Russian Federation); Odzhaev, V.B. [Belarusian State University, Independence Avenue 4, 22050 Minsk (Belarus)

    2007-04-15

    Fe{sup +} ions (40 keV) were implanted into polyethyleneterephthalate (PET) films with fluences of (0.25-1.5) x 10{sup 17} cm{sup -2}. Magnetic properties of the synthesised Fe:PET composites were studied using superconducting quantum interference device (SQUID) technique in temperature range of 2-300 K. For range of fluences (0.5-0.75) x 10{sup 17} cm{sup -2} the samples reveal superparamagnetic behaviour at room temperature. At fluences above 0.75 x 10{sup 17} cm{sup -2} the strong increase of magnetisation and transition to ferromagnetic properties are registered. Analysis of the magnetic hysteresis loops suggests an easy plane magnetic anisotropy similar to that found for thin magnetic films. Zero-field-cooled (ZFC) and field-cooled (FC) temperature measurements of magnetisation are found to be in agreement with earlier observed formation of Fe nanoparticles (NPs) in the implanted layers. The growth and agglomeration of the NPs forming the quasi-continuous labyrinth-like structure in the polymer film at the highest implantation fluence of 1.5 x 10{sup 17} cm{sup -2} is an origin for the transition to the ferromagnetic properties.

  16. Characteristics of Magnetic Properties of Substituted Hexagonal Ferrites

    Directory of Open Access Journals (Sweden)

    Vladimir Jancarik

    2006-01-01

    Full Text Available The samples of barium hexaferrite BaFe12-2x(Me1Me2xO19 with x from 0.0 to 0.6 were prepared by variousmethods. The cationic preference of mainly divalent Me1 = Zn, Co, Ni, Sn ions and tetravalent Me2 = Ti, Zr, Ir, Sn, Ru ionsand their combinations in substituted Ba ferrites was investigated. The substitutions were performed to reduce the grain sizeand high magnetic uniaxial anisotropy field of the M-type Ba ferrite without affecting the magnetic polarisation. The goal isto reach the properties of ferrite proper for high-density magnetic recording and microwave absorption devices. Magneticproperties were determined as a function of the substitution level x. The specific saturation magnetic polarisation Js–m andremanence Js–rincreased with small x due to the substitution of non-magnetic and less magnetic ions in 4f1 and 4f2 sites. Thesteep decrease of coercivity Hc with increasing x may be caused by the Co2+ preference of 4f2 site and Ti4+or Zr4+ions preference of 2b and slightly in 4f1 sites. The temperature coefficient of the coercivity TKHc was very low (0.01kA.m-1.°C-1for the Co-Zr substitutions and positive for the rest of samples.

  17. Electronic and magnetic properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Yee Yeen; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    We report a theoretical study of the electronic and magnetic properties of rhodium-atomic clusters. The lowest energy structures at the semi-empirical level of rhodium clusters are first obtained from a novel global-minimum search algorithm, known as PTMBHGA, where Gupta potential is used to describe the atomic interaction among the rhodium atoms. The structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof generalized gradient approximation. For the purpose of calculating the magnetic moment of a given cluster, we calculate the optimized structure as a function of the spin multiplicity within the DFT framework. The resultant magnetic moments with the lowest energies so obtained allow us to work out the magnetic moment as a function of cluster size. Rhodium atomic clusters are found to display a unique variation in the magnetic moment as the cluster size varies. However, Rh{sub 4} and Rh{sub 6} are found to be nonmagnetic. Electronic structures of the magnetic ground-state structures are also investigated within the DFT framework. The results are compared against those based on different theoretical approaches available in the literature.

  18. Magnetic properties of tetrataenite-rich meteorites. Pt. 2

    International Nuclear Information System (INIS)

    Magnetic hysteresis and thermomagnetic characteristics of St. Severin (LL6), Appley Bridge (LL6) and Tuxtuac (LL5) chondrites, which contain tetrataenite in their metallic components, are measured and analyzed in comparison with another tetrataenite-rich chondrite, Yamato 74160. The magnetic properties of tetrataenite-rich meteorites are characterized by (a) high magnetic coercive force (H sub(C)) which amounts to 520 Oe for St. Severin and 160 Oe for Appley Bridge, (b) essential flatness up to about 5000C and then a sharp irreversible drop down to Curie point of the first-run heating thermomagnetic curve. Both characteristic features are broken down to the ordinary features of disordered taenite by a breakdown of tetrataenite structure at elevated temperatures beyond the order-disorder transition temperature. The natural remanent magnetization (NRM) of tetrataenite-rich meteorites is extremely stable against AF-demagnetization and other magnetic disturbances because of the high magnetic coercivity of tetrataenite. The breakdown processes of ordered tetrataenite structure by heat treatments are experimentally pursued for the purpose of research of a possible formation process of tetrataenite phase in meteorites. (Author)

  19. Properties of Mesons in a Strong Magnetic Field

    CERN Document Server

    Zhang, Rui; Liu, Yu-xin

    2016-01-01

    By extending the $\\Phi$-derivable approach in Nambu-Jona-Lasinio model to finite magnetic field we calculate the properties of pion, $\\sigma$ and $\\rho$ mesons in a magnetic field at finite temperature in not only the quark-antiquark bound state scheme but also the pion-pion scattering resonant state scenario. Our calculation results manifest that the masses of $\\pi^{0}$ and $\\sigma$ meson can be nearly degenerate at the pseudo-critical temperature which increases with increasing the magnetic field strength, and the $\\pi^{\\pm}$ mass ascends suddenly at almost the same critical temperature. While the $\\rho$ mesons' masses decrease with the temperature but increase with the magnetic field strength. We also check the Gell-Mann-Oakes-Renner relation and find that the relation can be violated obviously with increasing the temperature, and the effect of the magnetic field becomes pronounced around the critical temperature. With different criteria, we analyze the effect of the magnetic field on the chiral phase tran...

  20. Magnetic and optical properties of polycarbonate/Fe nanocomposites

    Institute of Scientific and Technical Information of China (English)

    Ya SHI; Zheng-cao LI; Chun-hua XU; Wei MIAO; Yu-quan WANG; Zheng-jun ZHANG

    2008-01-01

    The magnetic and optical properties of poly-carbonate (PC)/Fe nanocomposite films prepared by a solution blended process and the role of Fe additives are investigated. The saturation magnetization of the PC/Fe nanocomposites depends on the weight of Fe nanoparti-cles. Meanwhile, an increase of photoluminescence (PL) intensity with decreasing Fe additives is interpreted. The optical band gap corresponds to the increase of PL ele-ments. The transmittance of the films increases with reduced Fe, and the PL peak energy of PC/Fe composites is also correlated to the weight ratio.

  1. Optical Writing of Magnetic Properties by Remanent Photostriction

    Science.gov (United States)

    Iurchuk, V.; Schick, D.; Bran, J.; Colson, D.; Forget, A.; Halley, D.; Koc, A.; Reinhardt, M.; Kwamen, C.; Morley, N. A.; Bargheer, M.; Viret, M.; Gumeniuk, R.; Schmerber, G.; Doudin, B.; Kundys, B.

    2016-09-01

    We present an optically induced remanent photostriction in BiFeO3 , resulting from the photovoltaic effect, which is used to modify the ferromagnetism of Ni film in a hybrid BiFeO3/Ni structure. The 75% change in coercivity in the Ni film is achieved via optical and nonvolatile control. This photoferromagnetic effect can be reversed by static or ac electric depolarization of BiFeO3 . Hence, the strain dependent changes in magnetic properties are written optically, and erased electrically. Light-mediated straintronics is therefore a possible approach for low-power multistate control of magnetic elements relevant for memory and spintronic applications.

  2. Magnetic properties of diamond shaped Ni80Fe20 nanomagnets

    International Nuclear Information System (INIS)

    We investigate the magnetic properties of Ni80Fe20 diamond-shaped nanomagnets as a function of the film thickness (t) in the range of 10-120 nm. The samples were fabricated using deep ultraviolet lithography at 248 nm exposure wavelength. We observed that for t ≥ 30 nm, the diamond-shaped structure exhibits flux closure configuration at remanence. A systematic thickness-dependent study reveals that the demagnetizing field across the plane of the structure strongly influences the reversal process. Our experimental results were substantiated by micro-magnetic simulations

  3. Magnetic and electric properties of C-Co thin films prepared by vaccum arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Tembre, A.; Clin, M.; Picot, J.-C. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Dellis, J.-L., E-mail: jean-luc.dellis@u-picardie.fr [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Henocque, J. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Bouzerar, R. [Laboratoire de Physique des Systemes Complexes, Universite de Picardie Jules Verne, 33 rue Saint leu, 80039 Amiens (France); Djellab, K. [Plate-forme de Microscopie Electronique, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France)

    2011-09-15

    Highlights: > Cobalt doped carbon thin films have been deposited by pulsed anodic electric arc technique. > The films are composed of well-crystallized cobalt layers and complex graphitic microstructure. > An insulating to a metallic state transition at 60 K is observed. > The magnetic susceptibility measurements show anomalous behaviour around 60 K. - Abstract: Cobalt doped carbon thin films have been deposited by a pulsed anodic electric arc technique. The films were characterized by high resolution transmission electron microscopy, electric measurements under dc magnetic fields, and ac magnetic susceptibility measurements within a temperature range 15-300 K. An insulating to a metallic state transition at a critical temperature around 60 K was observed.

  4. Magnetic properties and magnetization behavior of SmCo-based magnets with TbCu7-type structure

    Institute of Scientific and Technical Information of China (English)

    PAN Minxiang; ZHANG Pengyue; GE Hongliang; WU Qiong; YU Nengjun

    2013-01-01

    The nanocrystalline magnets with nominal compositions of Sm1-xLuxCo6.8Zr0.2 (x=0,0.2,0.4,0.6) were prepared directly by the intensive milling.The effects of Lu content on the phase structure,the magnetic properties,and magnetization behaviors were also investigated.The XRD patterns of the as-milled samples showed a single SmCo7 phase with TbCu7 structure.Lu addition was proved to result in relevant improvements in the microstructure and magnetic properties,especially in the maximum energy product (BH)max.It was shown that a higher maximum energy product and coercivity of about 17.47 kJ/m3 and 473.45 kA/m were obtained in the sample with x=0.2.From the analysis of the magnetization reversal behavior,it was found that a stronger intergrain exchange coupling interaction was observed in the samples with Lu-doping.From the studies of the coercivity mechanism,it was shown that nucleation model was the dominant magnetization reversal process at the elevated temperature.

  5. A study of uranium-based multilayers: II. Magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Springell, R; Zochowski, S W [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Ward, R C C; Wells, M R [Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Brown, S D; Bouchenoire, L; Wilhelm, F; Stirling, W G [European Synchrotron Radiation Facility, BP220, F-38043 Grenoble Cedex 09 (France); Langridge, S [ISIS, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Lander, G H [European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, Karslruhe, D-76125 (Germany)], E-mail: ross.springell@esrf.fr

    2008-05-28

    SQUID magnetometry and polarized neutron reflectivity (PNR) measurements have been employed to characterize the magnetic properties of U/Fe, U/Co and U/Gd multilayers. The field dependence of the magnetization was measured at 10 K in magnetic fields up to 70 kOe. A reduction in the magnetic moment was found for all systems. Magnetic 'dead' layers of {approx}15 A were determined for U/Fe and U/Co samples, indicative of chemically diffuse interfaces. For very thick layers, magnetic moments close to the bulk values were expected. For the U/Gd system, a large reduction in the magnetic moment, constant over a wide range of Gd layer thicknesses, was found ({approx}4 {mu}{sub B} compared with 7.63 {mu}{sub B} for the bulk metal). A possible explanation for this behaviour, consistent with observations of the structure of these multilayers, is that the Gd moments are pinned at the boundaries of column-like crystallites within the Gd layers. A study of the effective anisotropy and of a finite-size scaling behaviour of the U/Gd system is also presented. PNR data were collected in a field of 4.4 kOe for U/Fe and U/Co samples (at room temperature) and for U/Gd samples (at 10 K). Model calculations of the reflectivities used inputs extracted from the structural survey carried out on these systems, combined with data from the bulk magnetization measurements.

  6. Structural and magnetic properties of GeMn layers; High Curie temperature ferromagnetism induced by self organized GeMn nano-columns

    Energy Technology Data Exchange (ETDEWEB)

    Devillers, T.; Jamet, M.; Barski, A.; Poydenot, V.; Dujardin, R.; Bayle Guillemaud, P.; Bellet Amalric, E.; Mattana, R. [Departement de Recherche Fondamentale sur la Matiere Condensee, Service de Physique des Materiaux et Microstructures, CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex (France); Rothman, J. [Laboratoire d' Electronique de Technologie de l' Information, Laboratoire Infrarouge, CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex (France); Cibert, J. [Laboratoire Louis Neel, CNRS, BP166, 38042 Grenoble Cedex 9 (France); Tatarenko, S. [Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint-Martin d' Heres (France)

    2007-01-15

    In this paper we report on the structural and magnetic properties of GeMn layers grown on Ge(001). We show that for the optimized Mn concentration (6%) and for optimized growth temperature (close to 130 C), GeMn samples exhibit a high Curie temperature (higher than 400 K) and Anomalous Hall Effect up to room temperature. Our GeMn layers grown at low temperature (70 C to 130 C) are composed of vertical Mn-rich nano-columns. Samples grown at temperatures higher than 130 C contain GeMn nanoclusters. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Magnetic structure and magnetic transport properties of graphene nanoribbons with sawtooth zigzag edges.

    Science.gov (United States)

    Wang, D; Zhang, Z; Zhu, Z; Liang, B

    2014-12-23

    The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. It is found that all-sized ground-state STGNRs are ferromagnetic and always feature magnetic semiconductor properties, whose spin splitting energy gap E(g) changes periodically with the width of STGNRs. More importantly, for the STGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 10(10) can be predicted. Particularly, a highly effective spin-valve device is likely to be realized, which displays a giant magnetoresistace (MR) approaching 10(10)%, which is three orders magnitude higher than the value predicted based on the zigzag graphene nanoribbons and six orders magnitude higher than previously reported experimental values for the MgO tunnel junction. Our findings suggest that STGNRs might hold a significant promise for developing spintronic devices.

  8. Magnetic properties of ultrathin tetragonal Heusler D022-Mn3Ge perpendicular-magnetized films

    Science.gov (United States)

    Sugihara, A.; Suzuki, K. Z.; Miyazaki, T.; Mizukami, S.

    2015-05-01

    We investigated the crystal structure and magnetic properties of Manganese-germanium (Mn3Ge) films having the tetragonal D022 structure, with varied thicknesses (5-130 nm) prepared on chromium (Cr)-buffered single crystal MgO(001) substrates. A crystal lattice elongation in the in-plane direction, induced by the lattice mismatch between the D022-Mn3Ge and the Cr buffer layer, increased with decreasing thickness of the D022-Mn3Ge layer. The films exhibited clear magnetic hysteresis loops with a squareness ratio close to unity, and a step-like magnetization reversal even at a 5-nm thickness under an external field perpendicular to the film's plane. The uniaxial magnetic anisotropy constant of the films showed a reduction to less than 10 Merg/cm3 in the small thickness range (≤20 nm), likely due to the crystal lattice elongation in the in-plane direction.

  9. The effect of magnetic annealing on crystallographic texture and magnetic properties of Fe-2.6% Si

    Energy Technology Data Exchange (ETDEWEB)

    Salih, M.Z., E-mail: mohammedzs2007@hotmail.com [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Uhlarz, M. [Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden (Germany); Pyczak, F. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Brokmeier, H.-G. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Weidenfeller, B. [Institut für Elektrochemie, Abteilung für Materialwissenschaft, Arnold-Sommerfeld-Straße 6, D-38678 Clausthal-Zellerfeld (Germany); Al-hamdany, N. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Gan, W.M. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Zhong, Z.Y. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Schell, N. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany)

    2015-05-01

    The effect of magnetic annealing on crystallographic texture, microstructure, defects density and magnetic properties of a Fe-2.6% Si steel has been analyzed. After two stage cold rolling (75% and 60% cold rolled) with intermediate annealing process at (600 °C/1 h) the sample annealed at 600 °C for one hour during which different magnetic field of 0, 7 and 14 T were applied has been investigated. The effect of defects density after cold rolling process on the recrystallization texture and magnetic properties was characterized. Heat treatments under a high external field of 14 T show a drastic improvement of the magnetic properties such as significantly increased permeability. Neutron diffraction measurements were preferred for measurement of the bulk sample texture so that sufficient grain statistics were obtained. Because of its small wavelength (0.05–0.2 Å) Synchrotron diffraction with high photon energy was used to evaluate the defects density by a modified Williamson–Hall plot. - Highlights: • We show the effect of the magnetic annealing after intermediate cold rolling on the crystallographic texture and magnetic properties. • Due the coarse grained we used Neutron diffraction for texture measurement. • We used hysteresis recorder to measure the magnetic properties. • The magnetic annealing leads to drastic improvements of the magnetic properties such as significantly increased permeability. • We show the effect of defect density on the crystallographic texture and magnetic properties.

  10. Magnetic Properties of Diluted Magnetic Semiconductor Hg0.89Mn0.11Te

    Institute of Scientific and Technical Information of China (English)

    WANG Zewen; JIE Wanqi

    2015-01-01

    The magnetization of Hg0.89Mn0.11Te single crystal grown by vertical Bridgman method was studied by using superconducting quantum interference device magnetometer (SQUID Magnetometer). First, magnetization measurements were done under various magnetic ifeld strengths from-20 kOe to 20 kOe at 5 K, 15 K, and 77 K, respectively. Then, the magnetizations were measured with continuous changes of temperature in the range from 5 K to 300 K under the magnetic ifeld of 0.1 kOe and 10 kOe, respectively. The modiifed Brillouin function was well fitted with the data of magnetization vs. magnetic field strength. The analysis indicated that there was an antiferromagnetic exchange coupling among Mn2+ions. The results of reciprocal susceptibility vs. temperature ift Curie-Weiss law very well at the temperatures above 40 K, but deviate from the law from 5 K to 40 K, which shows that the antiferromagnetic exchange coupling among Mn2+ions increases in the lower temperature range below 40 K. The experimental result was explained by extending higher-order terms in the calculation of susceptibility and fitted by a power law function. The measurements reveal that Hg0.89Mn0.11Te possesses paramagnetic properties at temperatures from 5 K to 300 K.

  11. On magnetic properties of Cr2V4O13

    International Nuclear Information System (INIS)

    Recently we have reported detailed crystal structure and thermal stability of Cr2V4O13, a vanadium rich composition in Cr2O3-V2O5 system. It is observed that the crystal structure of Cr2V4O13 consists of two types of Cr2O10 dimers and U shaped V4O13)6- units as building units. The cyclo (V4O13)6- links the Cr2O10 dimers at the corners forming a three dimensional network structure. The presence of the octahedral dimers in the structure is expected to show interesting magnetic properties due to strong interaction of the spins of Cr3+. In order to observe the magnetic behaviour, detailed epr and temperature and field dependent magnetization studies on Cr2V4O13 were carried out and the results are in this abstract

  12. Magnetic properties related to thermal treatment of pyrite

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Detailed rock magnetic experiments were conducted on high-purity natural crystalline pyrite and its products of thermal treatments in both argon and air atmospheres. In argon atmosphere (reducing environment), the pyrite is altered by heating to magnetite and pyrrhotite; the latter is stable in argon atmosphere, and has coercive force and coercivity of remanence of ~20 and ~30 mT, respectively. Whereas in air, the pyrite is ultimately oxidized to hematite. First order reversal curve (FORC) diagram of the end product shows that the remanence coercivity of hematite is up to ~1400 mT. The corresponding thermal transformation process of pyrite in air can be simply summarized as pyrite→ pyrrhotite→magnetite→hematite. These results are helpful for understanding of sedimentary magnetism, secondary chemical remanence and meteorolite magnetic properties.

  13. Magnetic properties of nanocrystalline Ni Zn ferrites doped with samarium

    Science.gov (United States)

    Gama, L.; Diniz, A. P.; Costa, A. C. F. M.; Rezende, S. M.; Azevedo, A.; Cornejo, D. R.

    2006-10-01

    We describe the influence of the temperature of sintering on the structure and the static magnetic properties in Ni 0.5Zn 0.5Sm xFe 2-xO 4 ferrites prepared by combustion synthesis. The increase in Sm content increases the lattice parameter and decreases the mean grain size. The material treated at 600 °C should be single spinel ferrite but with low magnetization saturation. Calcinations carried out at 800 and 1000 °C resulted in materials with cubic spinel phase, but a small amount of SmFeO 3 was also formed. A smooth diminution of the saturation magnetization with an increase in Sm amount was observed. The highest Curie temperatures were obtained for sample treatment at 1000 °C with higher Sm content.

  14. Magnetic properties of self-organized L1{sub 0} FePtAg nanoparticle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Kang, S.S.; Nikles, D.E.; Harrell, J.W. E-mail: jharrell@bama.ua.edu; Wu, X.W

    2003-10-01

    The magnetic properties of chemically synthesized high anisotropy L1{sub 0} [Fe{sub 49}Pt{sub 51}]{sub 88}Ag{sub 12} nanoparticle arrays have been studied as a function of annealing temperature. Particles were prepared by the simultaneous polyol reduction of platinum acetylacetonate and silver acetate and the thermal decomposition of iron carbonyl, yielding monodispersed particles of diameter {approx}3.5 nm. Addition of Ag lowers the ordering temperature of self-assembled arrays by {approx}150 deg. C. After annealing at T{sub a}=500 deg. C for 30 min in an Ar/H{sub 2} atmosphere, the coercivity was 13,800 Oe. TEM and delta-M measurements indicate weak particle aggregation up to T{sub a}=400 deg. C, with evidence of sintering at higher temperatures. Large ratios of remanent to hysteresis coercivity indicate a large distribution in anisotropy energies. Anomalously large thermal stability constants, KV/k{sub B}T, and switching volumes were measured, even in samples with very little evidence of sintering. Zero field viscosity versus remanence curves show evidence of exchange interactions.

  15. Investigation of cryogenic irradiation influence on mechanical and physical properties of ITER magnetic system insulation materials

    International Nuclear Information System (INIS)

    A set of methods of cryogenic irradiation influence test on mechanical and physical properties of insulation of ITER magnetic system are presented in this paper. Investigations are carried out without intermediate warming up of samples. A Russian insulating composite material was irradiated in the IVV-2M reactor. The ratio of energy absorbed by insulation materials from neutron irradiation to that from gamma irradiation can be varied from ∝(25:75)% to ∝(50:50)% in the reactor. The test results on the thermal expansion, thermal conductivity and gas evolution of the above material are presented. It was shown, that cryogenic irradiation up to the fluence ∝2 x 1022 n/m2 (E ≥ 0.1 MeV) leads to 0.27% linear size changes along layers of fiber-glass, the thermal conductivity coefficient is decreased on 15% at 100 k in perpendicular direction to fiber-glass plane, and thermal coefficient of linear expansion (TCLE) has anomalous temperature dependence. (orig.)

  16. Frequency-Dependent Properties of Magnetic Nanoparticle Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Majetich, Sara [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-05-17

    In the proposed research program we will investigate the time- and frequency-dependent behavior of ordered nanoparticle assemblies, or nanoparticle crystals. Magnetostatic interactions are long-range and anisotropic, and this leads to complex behavior in nanoparticle assemblies, particularly in the time- and frequency-dependent properties. We hypothesize that the high frequency performance of composite materials has been limited because of the range of relaxation times; if a composite is a dipolar ferromagnet at a particular frequency, it should have the advantages of a single phase material, but without significant eddy current power losses. Arrays of surfactant-coated monodomain magnetic nanoparticles can exhibit long-range magnetic order that is stable over time. The magnetic domain size and location of domain walls is governed not by structural grain boundaries but by the shape of the array, due to the local interaction field. Pores or gaps within an assembly pin domain walls and limit the domain size. Measurements of the magnetic order parameter as a function of temperature showed that domains can exist at high temoerature, and that there is a collective phase transition, just as in an exchange-coupled ferromagnet. Dipolar ferromagnets are not merely of fundamental interest; they provide an interesting alternative to exchange-based ferromagnets. Dipolar ferromagnets made with high moment metallic particles in an insulating matrix could have high permeability without large eddy current losses. Such nanocomposites could someday replace the ferrites now used in phase shifters, isolators, circulators, and filters in microwave communications and radar applications. We will investigate the time- and frequency-dependent behavior of nanoparticle crystals with different magnetic core sizes and different interparticle barrier resistances, and will measure the magnetic and electrical properties in the DC, low frequency (0.1 Hz - 1 kHz), moderate frequency (10 Hz - 500

  17. A TALE OF THREE GALAXIES: ANOMALOUS DUST PROPERTIES IN IRAS F10398+1455, IRAS F21013–0739, AND SDSS J0808+3948

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yanxia; Hao, Lei [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Li, Aigen, E-mail: haol@shao.ac.cn [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)

    2014-10-20

    On a galactic scale, the 9.7 μm silicate emission is usually only seen in type 1 active galactic nuclei (AGNs). They usually also display a flat emission continuum at ∼5-8 μm and the absence of polycyclic aromatic hydrocarbon (PAH) emission bands. In contrast, starburst galaxies, luminous infrared (IR) galaxies, and ultraluminous IR galaxies exhibit a red 5-8 μm emission continuum, strong 9.7 μm and 18 μm silicate absorption features, and strong PAH emission bands. Here, we report the detection of anomalous dust properties by the Spitzer/Infrared Spectrograph in three galaxies (IRAS F10398+1455, IRAS F21013-0739, and SDSS J0808+3948) which are characterized by the simultaneous detection of a red 5-8 μm emission continuum, the 9.7 and 18 μm silicate emission features, as well as strong PAH emission bands. These apparently contradictory dust IR emission properties are discussed in terms of iron-poor silicate composition, carbon dust deficit, small grain size, and low dust temperature in the young AGN phase of these three galaxies.

  18. Electrochromic & magnetic properties of electrode materials for lithium ion batteries

    Science.gov (United States)

    Zheng-Fei, Guo; Kun, Pan; Xue-Jin, Wang

    2016-01-01

    Progress in electrochromic lithium ion batteries (LIBs) is reviewed, highlighting advances and possible research directions. Methods for using the LIB electrode materials’ magnetic properties are also described, using several examples. Li4Ti5O12 (LTO) film is discussed as an electrochromic material and insertion compound. The opto-electrical properties of the LTO film have been characterized by electrical measurements and UV-Vis spectra. A prototype bi-functional electrochromic LIB, incorporating LTO as both electrochromic layer and anode, has also been characterized by charge- discharge measurements and UV-Vis transmittance. The results show that the bi-functional electrochromic LIB prototype works well. Magnetic measurement has proven to be a powerful tool to evaluate the quality of electrode materials. We introduce briefly the magnetism of solids in general, and then discuss the magnetic characteristics of layered oxides, spinel oxides, olivine phosphate LiFePO4, and Nasicon-type Li3Fe2(PO4)3. We also discuss what kind of impurities can be detected, which will guide us to fabricate high quality films and high performance devices. Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA034201) and the Chinese Universities Scientific Fund (Grant No. 2015LX002).

  19. Magnetic and electronic properties of porphyrin-based molecular nanowires

    Directory of Open Access Journals (Sweden)

    Jia-Jia Zheng

    2016-01-01

    Full Text Available Using spin-polarized density functional theory calculations, we performed theoretical investigations on the electronic and magnetic properties of transition metal embedded porphyrin-based nanowires (TM-PNWs, TM = Cr, Mn, Co, Ni, Cu, and Zn. Our results indicate that Ni-PNW and Zn-PNW are nonmagnetic while the rest species are magnetic, and the magnetic moments in TM-PNWs and their corresponding isolated monomer structures are found to be the same. In addition, the spin coupling in the magnetic nanowires can be ignored leading to their degenerate AFM and FM states. These results can be ascribed to the weak intermetallic interactions because of the relatively large distances between neighbor TM atoms. Among all TM-PNW structures considered here, only Mn-PNW shows a half-metallic property while the others are predicted to be semiconducting. The present work paves a new way of obtaining ferromagnetic porphyrin-based nanowires with TM atoms distributed separately and orderly, which are expected to be good candidates for catalysts, energy storage and molecular spintronics.

  20. Non-destructive evaluation of mechanical properties of magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kankolenski, K.P.; Hua, S.Z.; Yang, D.X.; Hicho, G.E.; Swartzendruber, L.J.; Zang, Z.; Chopra, H.D.

    2000-07-01

    A magnetic-based non-destructive evaluation (NDE) method, which employs Barkhausen effect and measurement of the hysteresis loops, is used to correlate the magnetic and mechanical properties of ultra low carbon (ULC) steel. In particular, the NDE method was used to detect small deviations from linearity that occur in the stress-strain curve well below the 0.2% offset strain, and which generally defines the yield point in materials. Results show that three parameters: jumpsum and jumpsum rate (derived from the Barkhausen spectrum), and the relative permeability (derived from the B-H loops) varies sensitively with small permanent strains, and can be related to the plastic deformation in ULC steels. Investigation of micromagnetic structure revealed that plastic deformation leaves a residual stress state in the samples; the associated magneto-elastic energy makes the favorable easy axis of magnetization in a given grain to be the one that lies closest to the tensile axis. The consequence of this realignment of domains is that wall motion becomes intergranular in nature (as opposed to intragranular in unstrained samples). As a result, the more complex grain boundaries instead of dislocations, become the dominant pinning sites for domain walls. These observations provide a microscopic interpretation of the observed changes in the measured magnetic properties.

  1. The magnetic properties of the star Kepler-78

    Science.gov (United States)

    Moutou, C.; Donati, J.-F.; Lin, D.; Laine, R. O.; Hatzes, A.

    2016-06-01

    Kepler-78 is host to a transiting 8.5-h orbit super-Earth. In this paper, the rotation and magnetic properties of the planet host star are studied. We first revisit the Kepler photometric data for a detailed description of the rotation properties of Kepler-78, showing that the star seems to undergo a cycle in the spot pattern of ˜1300 d duration. We then use spectropolarimetric observations with Canada-France-Hawaii Telescope (CFHT)/ESPaDOnS to measure the circular polarization in the line profile of the star during its rotation cycle, as well as spectroscopic proxies of the chromospheric activity. The average field has a strength of 16 G. The magnetic topology is characterized by a poloidal and a toroidal component, encompassing 60 per cent and 40 per cent of the magnetic energy, respectively. Differential rotation is detected with an estimated rate of 0.105±0.039 rad d-1. Activity tracers vary with the rotation cycle of the star; there is no hint that a residual activity level is related to the planetary orbit at the precision of our data. The description of the star magnetic field's characteristics then may serve as input for models of interactions between the star and its close-by planet, e.g. Ohmic dissipation and unipolar induction.

  2. Electronic structure and magnetic properties of zigzag blue phosphorene nanoribbons

    International Nuclear Information System (INIS)

    We investigated the electronic structure and magnetism of zigzag blue phosphorene nanoribbons (ZBPNRs) using first principles density functional theory calculations by changing the widths of ZBPNRs from 1.5 to 5 nm. In addition, the effect of H and O passivation was explored as well. The ZBPNRs displayed intra-edge antiferromagnetic ground state with a semiconducting band gap of ∼0.35 eV; and this was insensitive to the edge structure relaxation effect. However, the edge magnetism of ZBPNRs disappeared with H-passivation. Moreover, the band gap of H-passivated ZBPNRs was greatly enhanced because the calculated band gap was ∼1.77 eV, and this was almost the same as that of two-dimensional blue phosphorene layer. For O-passivated ZBPNRs, we also found an intra-edge antiferromagnetic state. Besides, both unpassivated and O-passivated ZBPNRs preserved almost the same band gap. We predict that the electronic band structure and magnetic properties can be controlled by means of passivation. Moreover, the edge magnetism can be also modulated by the strain. Nonetheless, the intrinsic physical properties are size independent. This feature can be an advantage for device applications because it may not be necessary to precisely control the width of the nanoribbon

  3. Magnetic and electronic properties of porphyrin-based molecular nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jia-Jia; Li, Qiao-Zhi; Dang, Jing-Shuang; Zhao, Xiang, E-mail: xzhao@mail.xjtu.edu.cn [Institute for Chemical Physics & Department of Chemistry, MOE Key Laboratory for Non-equilibrium Condensed Matter and Quantum Engineering, School of Science, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Wei-Wei [Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)

    2016-01-15

    Using spin-polarized density functional theory calculations, we performed theoretical investigations on the electronic and magnetic properties of transition metal embedded porphyrin-based nanowires (TM-PNWs, TM = Cr, Mn, Co, Ni, Cu, and Zn). Our results indicate that Ni-PNW and Zn-PNW are nonmagnetic while the rest species are magnetic, and the magnetic moments in TM-PNWs and their corresponding isolated monomer structures are found to be the same. In addition, the spin coupling in the magnetic nanowires can be ignored leading to their degenerate AFM and FM states. These results can be ascribed to the weak intermetallic interactions because of the relatively large distances between neighbor TM atoms. Among all TM-PNW structures considered here, only Mn-PNW shows a half-metallic property while the others are predicted to be semiconducting. The present work paves a new way of obtaining ferromagnetic porphyrin-based nanowires with TM atoms distributed separately and orderly, which are expected to be good candidates for catalysts, energy storage and molecular spintronics.

  4. Structural and magnetic properties of chromium doped zinc ferrite

    International Nuclear Information System (INIS)

    Zinc chromium ferrites with chemical formula ZnCrxFe2−xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  5. Electrical and Magnetic Properties of FeSi2 Nanowires

    Institute of Scientific and Technical Information of China (English)

    PENG Zu-Lin; S. Liang

    2008-01-01

    We report the characterization of serf-assembled epitaxially grown FeSi2 nanowires (NWs) in terms of electrical and magnetic properties. NWs grown by reactive deposition epitaxy (RDE) on silicon (110) show dimensions of 1Onm×5nm, and several micrometres in length. By using conductive-AFM (c-AFM), electron transport properties of one single NW is measured, resistivity of a single crystalline FeSi2 NW is estimated to be 225 μΩ·cm.Using superconducting quantum interference device (SQUID), we measure a magnetic moment of 0.3±0.1 Bohr magneton per iron atom for these FeSi2 NWs.

  6. The New (g-2) Experiment: A proposal to measure the muon anomalous magnetic moment to ±0.14 ppm precision

    International Nuclear Information System (INIS)

    We propose to measure the muon anomalous magnetic moment, aμ, to 0.14 ppm-a fourfold improvement over the 0.54 ppm precision obtained in the BNL experiment E821. The muon anomaly is a fundamental quantity and its precise determination will have lasting value. The current measurement was statistics limited, suggesting that greater precision can be obtained in a higher-rate, next-generation experiment. We outline a plan to use the unique FNAL complex of proton accelerators and rings to produce high-intensity bunches of muons, which will be directed into the relocated BNL muon storage ring. The physics goal of our experiment is a precision on the muon anomaly of 16 x 10-11, which will require 21 times the statistics of the BNL measurement, as well a factor of 3 reduction in the overall systematic error. Our goal is well matched to anticipated advances in the worldwide effort to determine the standard model (SM) value of the anomaly. The present comparison, Δaμ (Expt: -SM) = (295 ± 81) x 10-11, is already suggestive of possible new physics contributions to the muon anomaly. Assuming that the current theory error of 51 x 10-11 is reduced to 30 x 10-11 on the time scale of the completion of our experiment, a future Δaμ comparison would have a combined uncertainty of ∼ 34 x 10-11, which will be a sensitive and complementary benchmark for proposed standard model extensions. The experimental data will also be used to improve the muon EDM limit by up to a factor of 100 and make a higher-precision test of Lorentz and CPT violation. We describe in this Proposal why the FNAL complex provides a uniquely ideal facility for a next-generation (g-2) experiment. The experiment is compatible with the fixed-target neutrino program; indeed, it requires only the unused Booster batch cycles and can acquire the desired statistics in less than two years of running. The proton beam preparations are largely aligned with the new Mu2e experimental requirements. The (g-2) experiment

  7. The uncertainties of magnetic properties measurements of electrical sheet steel

    CERN Document Server

    Ahlers, H

    2000-01-01

    In this work, uncertainties in measurements of magnetic properties of Epstein- and single-sheet samples have been determined according to the 'Guide To The Expression Of Uncertainty In Measurement', [International Organization for Standardization (1993)]. They were calculated for the results at predicted values of parameters taking into account the non-linear dependences. The measurement results and the uncertainties are calculated simultaneously by a computer program.

  8. Magnetic Properties of FePd Nanoparticles Prepared by Sonoelectrodeposition

    Science.gov (United States)

    Luong, Nguyen Hoang; Trung, Truong Thanh; Loan, Tran Phuong; Kien, Luu Manh; Hong, Tran Thi; Nam, Nguyen Hoang

    2016-08-01

    Fe60Pd40 nanoparticles were prepared by sonoelectrodeposition. After annealing at various temperatures from 450°C to 700°C, the nanoparticles were found to have an ordered L10 structure and to show hard magnetic properties. Among the samples investigated, the nanoparticles annealed at 600°C exhibited the highest coercivity which amounts to 2.31 kOe at 2 K and 1.83 kOe at 300 K.

  9. Magnetic and electron-transport properties of spin-gapless semiconducting CoFeCrAl films

    Science.gov (United States)

    Sellmyer, David; Jin, Yunlong; Kharel, Parashu; Valloppilly, Shah; George, Tom; Balasubramanian, Balamurugan; Skomski, Ralph

    Recently, spin-gapless semiconductors (SGS) with a semiconducting or insulating gap in one spin channel and zero gap in the other at the Fermi level have attracted much attention due to their new functionalities such as voltage-tunable spin polarization, the ability to switch between spin-polarized n-type and p-type conduction, high spin polarization and carrier mobility. For the development of spintronic devices utilizing SGS, it is necessary to have a better understanding of the magnetic and transport properties of the thin films of these materials. In this study, the structural, magnetic, and electron-transport properties of a SGS material CoFeCrAl in the thin film geometry have been investigated. CoFeCrAl films were grown on atomically flat SiO2 substrates using magnetron sputtering. The Curie temperature was measured to be 550 K very close to the value reported for bulk CoFeCrAl. Electron-transport measurements on the oriented films revealed a negative temperature coefficient of resistivity, small anomalous Hall conductivity and linear field dependence of magnetoresistance, which are transport signatures of SGS. The effect of elemental compositions and structural ordering on the SGS properties of the CoFeCrAl films will be discussed. Research supported by NSF (Y. J.), DoE (B. B., D. J. S), ARO (T. A. G., S. R. V.), SDSU (P. K.), and NRI (Facilities).

  10. Drug delivery property, bactericidal property and cytocompatibility of magnetic mesoporous bioactive glass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi-Zhuo [The Education Ministry Key Lab of Resource Chemistry, Shanghai Normal University, Shanghai 200234 (China); Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Li, Yang [Shanghai Key Laboratory of Orthopedic Implant, Department of Orthopedic Surgery, Shanghai Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011 (China); Yu, Xi-Bin [The Education Ministry Key Lab of Resource Chemistry, Shanghai Normal University, Shanghai 200234 (China); Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Liu, Li-Na [Shanghai Key Laboratory of Orthopedic Implant, Department of Orthopedic Surgery, Shanghai Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011 (China); Zhu, Zhen-An, E-mail: zhuzhenan2006@126.com [Shanghai Key Laboratory of Orthopedic Implant, Department of Orthopedic Surgery, Shanghai Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011 (China); Guo, Ya-Ping, E-mail: ypguo@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry, Shanghai Normal University, Shanghai 200234 (China); Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China)

    2014-08-01

    A multifunctional magnetic mesoporous bioactive glass (MMBG) has been widely used for a drug delivery system, but its biological properties have been rarely reported. Herein, the effects of mesopores and Fe{sub 3}O{sub 4} nanoparticles on drug loading–release property, bactericidal property and biocompatibility have been investigated by using mesoporous bioactive glass (MBG) and non-mesoporous bioactive glass (NBG) as control samples. Both MMBG and MBG have better drug loading efficiency than NBG because they possess ordered mesoporous channels, big specific surface areas and high pore volumes. As compared with MBG, the Fe{sub 3}O{sub 4} nanoparticles in MMBG not only provide magnetic property, but also improve sustained drug release property. For gentamicin-loaded MMBG (Gent-MMBG), the sustained release of gentamicin and the Fe{sub 3}O{sub 4} nanoparticles minimize bacterial adhesion significantly and prevent biofilm formation against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). Moreover, the magnetic Fe{sub 3}O{sub 4} nanoparticles in MMBG can promote crucial cell functions such as cell adhesion, spreading and proliferation. The excellent biocompatibility and drug delivery property of MMBG suggest that Gent-MMBG has great potentials for treatment of implant-associated infections. - Highlights: • Multifunctional magnetic mesoporous bioactive glass is fabricated. • The bioactive glass has great biocompatibility. • The bioactive glass exhibits high drug loading–release properties. • The drug delivery system has bactericidal property. • Magnetic particles improve cell adhesion, spreading and proliferation.

  11. Synthesis and magnetic properties of single phase titanomagnetites

    Energy Technology Data Exchange (ETDEWEB)

    Schoenthal, W., E-mail: wms@andrew.cmu.edu; Liu, X.; Cox, T.; Laughlin, D. E.; McHenry, M. E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Mesa, J. L.; Diaz-Michelena, M. [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Maicas, M. [Universidad Politecnica de Madrid, ISOM-ETSIT, Madrid (Spain)

    2014-05-07

    The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe{sub 3}O{sub 4−x}Fe{sub 2}TiO{sub 4} solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe{sub 2}TiO{sub 4}), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.

  12. Microscopic and magnetic properties of template assisted electrodeposited iron nanowires

    Science.gov (United States)

    Irshad, M. I.; Ahmad, F.; Mohamed, N. M.; Abdullah, M. Z.; Yar, A.

    2015-07-01

    Nanowires of magnetic materials such as Iron, nickel, cobalt, and alloys of them are one of the most widely investigated structures because of their possible applications in high density magnetic recording media, sensor elements, and building blocks in biological transport systems. In this work, Iron nanowires have been prepared by electrodeposition technique using Anodized Aluminium Oxide (AAO) templates. The electrolyte used consisted of FeSO4.6H2O buffered with H3BO3 and acidized by dilute H2SO4. FESEM analysis shows that the asdeposited nanowires are parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. To fabricate the working electrode, a thin film of copper (˜ 220 nm thick) was coated on back side of AAO template by e-beam evaporation system to create electrical contact with the external circuit. The TEM results show that electrodeposited nanowires have diameter around 100 nm and are polycrystalline in structure. Magnetic properties show the existence of anisotropy for in and out of plane configuration. These nanowires have potential applications in magnetic data storage, catalysis and magnetic sensor applications.

  13. Magnetic and Magnetoelectric Properties of Rare Earth Molybdates

    Directory of Open Access Journals (Sweden)

    B. K. Ponomarev

    2012-01-01

    Full Text Available We present results on ferroelectric, magnetic, magneto-optical properties and magnetoelectric effect of rare earth molybdates (gadolinium molybdate, GMO, and terbium molybdate, TMO, and samarium molybdate, SMO, belonging to a new type of ferroelectrics predicted by Levanyuk and Sannikov. While cooling the tetragonal β-phase becomes unstable with respect to two degenerate modes of lattice vibrations. The β-β′ transition is induced by this instability. The spontaneous polarization appears as a by-product of the lattice transformation. The electric order in TMO is of antiferroelectric type. Ferroelectric and ferroelastic GMO and TMO at room temperature are paramagnets. At low temperatures GMO and TMO are antiferromagnetic with the Neel temperatures TN=0.3 K (GMO and TN=0.45 K (TMO. TMO shows the spontaneous destruction at 40 kOe magnetic field. Temperature and field dependences of the magnetization in TMO are well described by the magnetism theory of singlets at 4.2 K ≤ T ≤ 30 K. The magnetoelectric effect in SMO, GMO and TMO, the anisotropy of magnetoelectric effect in TMO at T = (1.8–4.2 K, the Zeeman effect in TMO, the inversion of the electric polarization induced by the laser beam are discussed. The correlation between the magnetic moment of rare earth ion and the magnetoelectric effect value is predicted. The giant fluctuations of the acoustic resonance peak intensity near the Curie point are observed.

  14. Microscopic and magnetic properties of template assisted electrodeposited iron nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Irshad, M. I., E-mail: imrancssp@gmail.com; Mohamed, N. M., E-mail: noranimuti-mohamed@petronas.com.my; Yar, A., E-mail: asfandyarhargan@gmail.com [Department of Fundamental & Applied Sciences, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia); Ahmad, F., E-mail: faizahmad@petronas.com.my; Abdullah, M. Z., E-mail: zaki-abdullah@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750 PERAK (Malaysia)

    2015-07-22

    Nanowires of magnetic materials such as Iron, nickel, cobalt, and alloys of them are one of the most widely investigated structures because of their possible applications in high density magnetic recording media, sensor elements, and building blocks in biological transport systems. In this work, Iron nanowires have been prepared by electrodeposition technique using Anodized Aluminium Oxide (AAO) templates. The electrolyte used consisted of FeSO{sub 4.}6H{sub 2}O buffered with H{sub 3}BO{sub 3} and acidized by dilute H{sub 2}SO{sub 4}. FESEM analysis shows that the asdeposited nanowires are parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. To fabricate the working electrode, a thin film of copper (∼ 220 nm thick) was coated on back side of AAO template by e-beam evaporation system to create electrical contact with the external circuit. The TEM results show that electrodeposited nanowires have diameter around 100 nm and are polycrystalline in structure. Magnetic properties show the existence of anisotropy for in and out of plane configuration. These nanowires have potential applications in magnetic data storage, catalysis and magnetic sensor applications.

  15. Structural and magnetic properties of sonoelectrocrystallized magnetite nanoparticles

    Science.gov (United States)

    Mosivand, S.; Monzon, L. M. A.; Ackland, K.; Kazeminezhad, I.; Coey, J. M. D.

    2014-02-01

    The effect of ultrasound power on the morphology, structure and magnetic properties of magnetite nanoparticles synthesized from iron electrodes by the electro-oxidation method was investigated. Samples made in aqueous solution in the absence or presence of an organic stabilizer (thiourea, tetramethylammonium chloride, sodium butanoate or β-cyclodextrine) were characterized by x-ray diffraction, transmission and scanning electron microscopy, magnetometry and Mössbauer spectrometry. The iron is almost all in the form of 20-85 nm particles of slightly nonstoichiometric Fe3-δO4, with δ ≈ 0.10. Formation of a paramagnetic secondary phase in the presence of sodium butanoate or β-cyclodextrine is supressed by ultrasound. Specific magnetization of the magnetite nanoparticles ranges from 19 to 90 A m2 kg-1 at room temperature, and it increases with particle size in each series. The particles show no sign of superparamagnetism, and the anhysteretic and practically temperature-independent magnetization curves are associated with a stable magnetic vortex state throughout the size range. The spin structure of the particles and the use of magnetization measurements to detect magnetite in unknown mixtures are discussed.

  16. Magnetic properties of Ni(II)-Mn(III) LDHs

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Zaghrioui, M.; Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Delorme, F.; Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 2 (France); Chartier, T.; Pignon, B. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France)

    2012-11-15

    The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions. -- Highlights: Black-Right-Pointing-Pointer The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides have been performed. Black-Right-Pointing-Pointer The low temperature magnetic behaviour of these compounds has been studied. Black-Right-Pointing-Pointer The substitution of Ni by Mn ions favours the in plane antiferromagnetic order.

  17. Properties of mesons in a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rui [Peking University, Department of Physics, State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Fu, Wei-jie [Universitaet Heidelberg, Institut fuer Theoretische Physik, Heidelberg (Germany); Liu, Yu-xin [Peking University, Department of Physics, State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Peking University, Center for High Energy Physics, Beijing (China)

    2016-06-15

    By extending the Φ-derivable approach in the Nambu-Jona-Lasinio model to a finite magnetic field we calculate the properties of pion, σ, and ρ mesons in a magnetic field at finite temperature not only in the quark-antiquark bound state scheme but also in the pion-pion scattering resonant state scenario. Our calculation as a result makes manifest that the masses of π{sup 0} and σ meson can be nearly degenerate at the pseudo-critical temperature which increases with increasing magnetic field strength, and the π{sup ±} mass ascends suddenly at almost the same critical temperature. Meanwhile the ρ mesons' masses decrease with the temperature but increase with the magnetic field strength. We also check the Gell-Mann-Oakes-Renner relation and find that the relation can be violated clearly with increasing temperature, and the effect of the magnetic field becomes pronounced around the critical temperature. With different criteria, we analyze the effect of the magnetic field on the chiral phase transition and find that the pseudo-critical temperature of the chiral phase cross, T{sub c}{sup χ}, is always enhanced by the magnetic field. Moreover, our calculations indicate that the ρ mesons will get melted as the chiral symmetry has not yet been restored, but the σ meson does not disassociate even at very high temperature. Particularly, it is the first to show that there does not exist a vector meson condensate in the QCD vacuum in the pion-pion scattering scheme. (orig.)

  18. Optical and magnetic properties of PAA@Fe nanocomposite films

    Directory of Open Access Journals (Sweden)

    Jing-jing Zhang

    2013-07-01

    Full Text Available A simple method to fabricate porous anodic alumina films embedded with Fe is reported. The films exhibit vivid structural colors and magnetic properties after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The coercivity mechanism of the Fe nanowires in our case is consistent with fanning reversal mode. PAA@Fe films can be used in many areas including decoration, display and multifunctional anti-counterfeiting applications.

  19. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

  20. Hematite nanoplates: Controllable synthesis, gas sensing, photocatalytic and magnetic properties.

    Science.gov (United States)

    Hao, Hongying; Sun, Dandan; Xu, Yanyan; Liu, Ping; Zhang, Guoying; Sun, Yaqiu; Gao, Dongzhao

    2016-01-15

    Uniform hematite (α-Fe2O3) nanoplates exposing {001} plane as basal planes have been prepared by a facile solvothermal method under the assistance of sodium acetate. The morphological evolution of the nanoplates was studied by adjusting the reaction parameters including the solvent and the amount of sodium acetate. The results indicated that both the adequate nucleation/growth rate and selective adsorption of alcohol molecules and acetate anions contribute to the formation of the plate-like morphology. In addition, the size of the nanoplates can be adjusted from ca. 180nm to 740nm by changing the reaction parameters. Three nanoplate samples with different size were selected to investigate the gas sensing performance, photocatalytic and magnetic properties. As gas sensing materials, all the α-Fe2O3 nanoplates exhibited high gas sensitivity and stability toward n-butanol. When applied as photocatalyst, the α-Fe2O3 nanoplates show high photodegradation efficiency towards RhB. Both the gas sensing performance and the photocatalytic property of the products exhibit obvious size-dependent effect. Magnetic measurements reveal that the plate-like α-Fe2O3 particles possess good room temperature magnetic properties.