Showing papers on "Spin wave published in 1996"
TL;DR: In this paper, the interaction between spin waves and itinerant electrons is considerably enhanced in the vicinity of an interface between normal and ferromagnetic layers in metallic thin films, leading to a local increase of the Gilbert damping parameter which characterizes spin dynamics.
Abstract: The interaction between spin waves and itinerant electrons is considerably enhanced in the vicinity of an interface between normal and ferromagnetic layers in metallic thin films. This leads to a local increase of the Gilbert damping parameter which characterizes spin dynamics. When a dc current crosses this interface, stimulated emission of spin waves is predicted to take place. Beyond a certain critical current density, the spin damping becomes negative; a spontaneous precession of the magnetization is predicted to arise. This is the magnetic analog of the injection laser. An extra dc voltage appears across the interface, given by an expression similar to that for the Josephson voltage across a superconducting junction. \textcopyright{} 1996 The American Physical Society.
4,433 citations
Book•
30 Nov 1996
TL;DR: In this paper, an analysis of Ferromagnetic Resonance in anisotropic Ferromagnet Magnetocrystalline Anisotropy originates from the origin of magnetically active materials.
Abstract: Isotropic Ferromagnet Magnetized to Saturation Ferromagnetism Elementary Magnetic Moments Paramagnetism Weiss Theory Exchange Interaction Equation of Motion of Magnetization High-Frequency Magnetic Susceptibility Solution of the Linearized Equation of Motion Peculiarities of the Susceptibility Tensor High-Frequency Permeability Allowance for Magnetic Losses Dissipative Terms and Dissipation Parameters Susceptibility Tensor Components Uniform Oscillations in a Small Ellipsoid Internal and External Magnetic Fields Eigenoscillations Forced Oscillations Anisotropic Ferromagnet Landau-Lifshitz Equation Generalization of Equation of Motion Methods of Analysis of Ferromagnetic Resonance in Anisotropic Ferromagnet Magnetocrystalline Anisotropy Origins of Magnetocrystalline Anisotropy Phenomenological Description Equilibrium Orientations of Magnetization Ferromagnetic Resonance in a Single Crystal Sphere of Uniaxial Ferromagnet Sphere of a Cubic Ferromagnet Simultaneous Allowance for Different Kinds of Anisotropy Ferromagnetic Resonance in a Polycrystal Independent-Grain and Strongly-Coupled Grain Approximations Influence of Porosity Antiferromagnets and Ferrites Antiferromagnetism and Ferrimagnetism Crystal and Magnetic Structures Equations of Motion and Energy Terms Ground States and Small Oscillations Antiferromagnetic Resonance Antiferromagnet with an Easy Axis of Anisotropy: Steady States Oscillations in Antiparallel State Oscillations in Noncollinear State Oscillations in Transverse and Arbitrarily Oriented Fields Antiferromagnet with Easy Plane of Anisotropy Magnetic Oscillations in Ferrimagnets Ground States of Two-Sublattice Ferrimagnet Oscillations in Antiparallel Ground State Oscillations in Noncollinear Ground State Damped and Forced Oscillations Fundamentals of Electrodynamics of Gyrotropic Media Equations General Equations and Boundary Conditions Equations for Bigyotropic Media Uniform Plane Waves General Relations Longitudinal Magnetization Transverse Magnetization Nonreciprocity Energy Relations Equation of Energy Balance Energy Losses Perturbation Method Gyrotropic Perturbation of a Waveguide Gyrotropic Perturbation of a Resonator Quasistatic Approximation Resonator with Walls of Real Metal Waveguides and Resonators with Gyrotropic Media. Microwave Ferrite Devices Waveguide with Longitudinally Magnetized Medium Circular Waveguide Circular Waveguide with Ferrite Rod Faraday Ferrite Devices Waveguide with Transversely Magnetized Ferrite Rectangular Waveguide Filled with Ferrite Rectangular Waveguide with Ferrite Plates Microwave Ferrite Devices Resonators with Gyrotropic Media Eigenoscillations and Forced Oscillations Waveguide Resonators Ferrite Resonators Use of Perturbation Method Waveguides and Waveguide Junctions with Ferrite Samples Ferrite Ellipsoid in a Waveguide Coupling of Orthogonal Waveguides. Ferrite Band-Pass Filters General Properties of Nonreciprocal Junctions Magnetostatic Waves and Oscillations Magnetostatic Approximation Nonexchange Magnetostatic Waves in Plates and Rods Volume Waves in Plates Surface Waves Magnetostatic Waves in Waveguides with Finite Cross Section Energy Flow and Losses Magnetostatic Waves in Ferrite Films: Excitation, Applications Magnetostatic Oscillations (Walker's Modes) Metallized Cylinder Sphere and Ellipsoid of Revolution Damping, Excitation, and Coupling Spin Waves Spin Waves in Unbounded Ferromagnet Energy and Effective Field of Exchange Interaction Dispersion Law Magnetization, Field Components, and Damping Spin Waves in Bounded Bodies Exchange Boundary Conditions Standing Spin Waves in Films Propagating Spin Waves in Films Spin Waves in Nonuniform Magnetic Fields Magnons Quantization of Magnetic Oscillations and Waves Thermal Magnons Elements of Microscopic Spin-Wave Theory Diagonalization of the Hamiltonian Discussion of the Dispersion Law Allowance for Dipole-Dipole Interaction and Anisotropy Interaction of Magnons Magnetic Oscillations and Waves in Unsaturated Ferromagnet Oscillations of Domain Walls Domain Walls and Domain Structures Equation of Motion of a Domain Wall Dynamic Susceptibility Ferromagnetic Resonance in Samples with Domain Structure Ellipsoid of Uniaxial Ferromagnet Sphere of Cubic Ferromagnet Nonuniform Modes in Unsaturated Samples Nonlinear Oscillations of Magnetization Ferromagnetic Resonance in Strong Alternating Fields Rigorous Solution of Equation of Motion Approximate Methods Harmonic Generation and Frequency Conversion Frequency Doubling Frequency Mixing Parametric Excitation of Magnetic Oscillations and Waves Nonlinear Coupling of Magnetic Modes Thresholds of Parametric Excitation under Transverse Pumping First-Order and Second-Order Instabilities Threshold Fields Effect of Pumping-Field Polarization Longitudinal and Oblique Pumping Longitudinal Pumping Effect of Nonuniformities Oblique Pumping Instability of Nonuniform Modes and Nonuniform Pumping Parametric Excitation of Magnetostatic Oscillations and Waves Ferrite Parametric Amplifier Nonuniform Pumping Above-Threshold State Reaction of Parametric Spin Waves on Pumping Phase Mechanism Nonlinear Damping Stability of the Above-Threshold State Nonlinear Microwave Ferrite Devices Spin-Spin Relaxation Relaxation Processes in Magnetically Ordered Substances Kinds of Relaxation Processes Methods of Theoretical Study Inherent Spin-Spin Processes Three-Magnon Splitting Three-Magnon Confluence Four-Magnon Scattering Inherent Processes for Uniform Precession Experimental Data Two-Magnon Processes Theory of Two-Magnon Processes Disorder in Distribution of Ions over Lattice Sites Anisotropy-Field Variation and Pores in Polycrystals Surface Roughness Magnetoelastic Coupling Elastic Properties and Magnetoelastic Interaction Elastic Waves and Oscillations Magnetoelastic Energy and Equations of Motion Effect of Elastic Stresses on Ferromagnetic Resonance Magnetoelastic Waves Normal Waves Damping and Excitation Magnetoelastic Waves in Nonuniform Steady Magnetic Field Parametric Excitation of Magnetoelastic Waves Longitudinal Pumping of Magnetoelastic Waves Parametric Excitation Caused by Magnetoelastic Coupling Elastic Pumping Spin-Lattice Relaxation Ionic Anisotropy and Relaxation Anisotropy Caused by Impurity Ions Energy Levels of Ions One-Ion Theory of Ferromagnetic-Resonance Anisotropy Near-Crossing Energy Levels Experimental Data Ion Relaxation Processes Transverse Relaxation Longitudinal (Slow) Relaxation Relaxation of Ionic-Level Populations Experimental Data Interaction of Magnetic Oscillations and Waves with Charge Carriers Effect of Charge Carriers in Semiconductors Damping of Magnetic Oscillations Caused by Conductivity Influence of Interionic Electron Transitions Interaction of Spin Waves with Charge Carriers Ferromagnetic Resonance and Spin Waves in Metals Thin-Film Model Theory without Allowance for Exchange Interaction Influence of Exchange Interaction Antiresonance Processes of Magnetic Relaxation Appendices Units and Constants Demagnetization Factors Dirac Delta Function and Kronecker Delta Symbol Bibliography Subject Index to the Bibliography Index
1,022 citations
TL;DR: The dispersion of the spin waves propagating in the highest symmetry directions solving the problems related to twinning is measured and the whole spin wave spectrum is well accounted for.
Abstract: As part of a general work on doped manganese perovskites, we have carried out detailed neutron-scattering experiments on powder and single crystals of the othorhombic phase of undoped LaMn${\mathrm{O}}_{3}$. The temperature dependence of the sublattice magnetization has been determined in the antiferromagnetic phase (${T}_{N}=139.5$ K), and the critical exponent is $\ensuremath{\beta}=0.28$, well below that corresponding to a pure three-dimensional Heisenberg antiferromagnet. We have measured the dispersion of the spin waves propagating in the highest symmetry directions solving the problems related to twinning. The whole spin wave spectrum is well accounted for with a Heisenberg Hamiltonian and a single ion anisotropy term responsible for the easy magnetization direction (b axis). This term induces a gap of 2.7 meV at low temperature in the spin wave dispersion curve. An important result is that the ferromagnetic exchange integral (${J}_{1}\ensuremath{\approx}0.83$ meV), coupling the spins within the ferromagnetic basal plane (a,b), is larger by a factor 1.4 than the antiferromagnetic exchange integral (${J}_{2}\ensuremath{\approx}\ensuremath{-}0.58$ meV) coupling spins belonging to adjacent Mn${\mathrm{O}}_{2}$ planes along c.
239 citations
TL;DR: The superlattice reflection intensities are independent of temperature demonstrating that there is no primary lattice distortion anomaly at the magnetic transition temperature {ital T}{sub {ital C}}=378.1 K; however, there is a lattice contraction.
Abstract: Neutron scattering studies on a single crystal of the highly correlated electron system, La{sub 1{minus}{ital x}}Sr{sub {ital x}}MnO{sub 3} with {ital x}{approx_equal}0.3, have been carried out elucidating both the spin and lattice dynamics of this metallic ferromagnet. We report a large measured value of the spin wave stiffness constant, which directly shows that the electron transfer energy of the {ital d} band is large. The spin dynamics, including magnetic critical scattering, demonstrate that this material behaves similar to other typical metallic ferromagnets such as Fe or Ni. The crystal structure is rhombohedral, as previously reported, for all temperatures studied (below {approximately}425 K). We have observed superlattice peaks which show that the primary rhombohedral lattice distortion arises from oxygen octahedra rotations resulting in an {ital R}{bar 3}{ital c} structure. The superlattice reflection intensities, which are very sensitive to structural changes, are independent of temperature demonstrating that there is no primary lattice distortion anomaly at the magnetic transition temperature {ital T}{sub {ital C}}=378.1 K; however, there is a lattice contraction. {copyright} {ital 1996 The American Physical Society.}
236 citations
TL;DR: In this paper, the static and dynamical properties of weakly coupled antiferromagnetic spin chains are treated using a mean-field approximation for the interchain coupling and exact results for the resulting effective one-dimensional problem.
Abstract: Static and dynamical properties of weakly coupled antiferromagnetic spin chains are treated using a mean-field approximation for the interchain coupling and exact results for the resulting effective one-dimensional problem. Results for staggered magnetization, N\'eel temperature, and spin wave excitations are in agreement with experiments on ${\mathrm{KCuF}}_{3}$. The existence of a narrow longitudinal mode is predicted. The results are in agreement with general scaling arguments, contrary to spin wave theory.
211 citations
TL;DR: Inelastic neutron scattering is used to measure the spin wave dispersion throughout the Brillouin zone of the double-exchange ferromagnet La0.7Pb0.3MnO3 and yields unusual broadening of the high frequency spin waves, even within the ferromagnetic phase.
Abstract: We use inelastic neutron scattering to measure the spin wave dispersion throughout the Brillouin zone of the double-exchange ferromagnet La0.7Pb0.3MnO3. Magnons with energies as high as 95 meV are directly observed and an unexpectedly simple Heisenberg Hamiltonian, with solely a nearest-neighbor coupling of 8.79 +/- 0.21 meV, accounts for the entire dispersion relation. The calculated Curie temperature for this local moment Hamiltonian overestimates the measured Curie point (355 K) by only 15%. Raising temperature yields unusual broadening of the high frequency spin waves, even within the ferromagnetic phase.
144 citations
126 citations
TL;DR: In this article, the double exchange model on a cubic lattice was investigated for perovskite-type manganates and the spin excitation spectrum of the model in the ground state was studied using the spin wave approximation.
Abstract: As an effective model to describe perovskite-type manganates (La,$A$)MnO$_3$, the double-exchange model on a cubic lattice is investigated. Spin excitation spectrum of the model in the ground state is studied using the spin wave approximation. Spin wave dispersion relation observed in the inelastic neutron scattering experiment of La$_{0.7}$Pb$_{0.3}$MnO$_3$ is reproduced. Effective values for the electron bandwidth as well as Hund's coupling is estimated from the data.
97 citations
TL;DR: In this article, the double-exchange model with ferromagnetic couplings on a cubic lattice is investigated, and the spin excitation spectrum of the model in the ground state is studied using the spin wave approximation.
Abstract: As an effective model to describe the perovskite-type manganates (La, A )MnO 3 , the double-exchange model (the Kondo lattice model with ferromagnetic couplings) on a cubic lattice is investigated. The spin excitation spectrum of the model in the ground state is studied using the spin wave approximation. The spin wave dispersion relation observed in the inelastic neutron scattering experiment for La 0.7 Pb 0.3 MnO 3 is reproduced. Effective values for the electron bandwidth as well as Hund's coupling are estimated from the data.
96 citations
TL;DR: The critical exponent β of the order parameter is 0.25 ± 0.01 as discussed by the authors, which is much smaller than values obtained for the three-dimensional Ising (0.326) and Heisenberg model.
Abstract: Neutron-scattering experiments have been performed on a LaMnO 3 single crystal. The spin waves exhibit two-dimensional anisotropic dispersion, that is, strong planar ferromagnetic coupling and weak antiferromagnetic interplane coupling with a finite gap. The critical exponent β of the order parameter is 0.25 ±0.01, which is much smaller than values obtained for the three-dimensional Ising (0.326) and Heisenberg (0.367) models. Ferromagnetic spin-wave-like dispersion remains for ω> 10 meV at T c ≈140 K, though the spectrum near the zone center is entirely overdamped around ω= 0.
93 citations
TL;DR: The antiferromagnetic spin-density-wave (SDW) order of Cr layers in Fe/Cr(001) superlattices was investigated by neutron scattering to find a coherent magnetic structure near the Fe-Cr interfaces.
Abstract: The antiferromagnetic spin-density-wave (SDW) order of Cr layers in Fe/Cr(001) superlattices was investigated by neutron scattering. For Cr thickness 51-190 {Angstrom}, a transverse SDW is formed for all temperatures below Neel temperature with a single wavevector Q normal to the layers. A coherent magnetic structure forms with the nodes of the SDW near the Fe-Cr interfaces. For thinner Cr layers, the magnetic scattering can be described by commensurate antiferromagnetic order.
TL;DR: A quantum field theory for nonuniform spin configurations is derived within a coherent state path integral approach and external fields can be used to interpolate continuously between the Bloch wall dispersions for half-integer and integer spin.
Abstract: We study spin parity effects and the quantum propagation of solitons (Bloch walls) in quasi-one-dimensional ferromagnets. Within a coherent state path integral approach we derive a quantum field theory for nonuniform spin configurations. The effective action for the soliton position is shown to contain a gauge potential due to the Berry phase and a damping term caused by the interaction between soliton and spin waves. For temperatures below the anisotropy gap this dissipation reduces to a pure soliton mass renormalization. The quantum dynamics of the soliton in a periodic lattice or pinning potential reveals remarkable consequences of the Ferry phase. For half-integer spin, destructive interference between opposite chiralities suppresses nearest-neighbor hopping. Thus the Brillouin zone is halved, and for small mixing of the chiralities the dispersion reveals a surprising dynamical correlation. Two subsequent band minima belong to different chirality states of the soliton. For integer spin the Ferry phase is inoperative and a simple tight-binding dispersion is obtained. Finally it is shown that external fields can be used to interpolate continuously between the Bloch wall dispersions for half-integer and integer spin.
TL;DR: It is found that muon polarization obeys a time-field scaling relation which allows us to distinguish between three possible forms of the spin-spin dynamical autocorrelation function: a power law, a stretched exponential, and a cutoff power law.
Abstract: We report zero and longitudinal field muon spin relaxation measurements in the metallic spin glass AgMn(0.5 at. %) at $Tg{T}_{g}$. We find that muon polarization obeys a time-field scaling relation which allows us to distinguish between three possible forms of the spin-spin dynamical autocorrelation function: a power law, a stretched exponential, and a cutoff power law. We also discuss the evolution of the muon relaxation line shape as the temperature approaches ${T}_{g}$.
TL;DR: Brillouin light scattering is utilized to investigate the magnetic properties of the hexagonal-close-packed as well as the body- and face-centered cubic phases of elemental cobalt stabilized as thin epilayers and the implications towards the understanding of magnetic property of itinerant ferromagnets are discussed.
Abstract: We utilize Brillouin light scattering to investigate the magnetic properties of the hexagonal-close-packed as well as the body- and face-centered cubic phases of elemental cobalt stabilized as thin epilayers. Expressions for the dependence of the surface and bulk magnons on applied magnetic field and in-plane propagation direction yield the exchange stiffness constant D, saturation magnetization M, and magnetic anisotropy fields of the cobalt atoms synthesized in these distinct crystal structures. Estimates of D and M are also calculated from the electronic band structure for the different crystalline phases. Satisfactory agreement is found between theory and experiment. The implications of these results towards our understanding of magnetic properties of itinerant ferromagnets are discussed. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this paper, the magnetic properties of single-crystal Cu 0.966 Zn 0.034 GeO 3 doped with Zn have been investigated and it was shown that the magnetic Bragg peaks are not saturated even at 1.4 K, and the long range ordered magnetic moment is only ∼0.2 µ B per Cu site.
Abstract: A recent study of the magnetic susceptibility in single crystals of the spin-Peierls material CuGeO 3 doped with Zn indicates antiferromagnetic order at low temperatures. In the present publication, we report a neutron scattering investigation of the static and dynamic magnetic properties of single-crystal Cu 0.966 Zn 0.034 GeO 3 . Below the transition temperature of 4.2 ± 0.3 K, sharp magnetic Bragg peaks are observed at the magnetic superlattice positions (0 k l /2) with both k and l odd. However, the intensities of these peaks are not saturated even at 1.4 K, and the long range ordered magnetic moment is only ∼0.2 µ B per Cu site. Moreover, no well-defined spin-wave-like excitations are seen. Instead, overdamped magnetic excitations appear around the magnetic Bragg peaks at low temperatures. These results suggest an unusual state of magnetic order incorporating considerable magnetic and possibly structural disorder. We speculate that this unusual order is caused by a spatial distribution of spin states...
TL;DR: The complete spectrum of the double spinon excitation in the spin-Peierls system CuGe${\mathrm{O}}_{3}$ is mapped as a function of temperature for the first time.
Abstract: The complete spectrum of the double spinon excitation in the spin-Peierls system CuGe${\mathrm{O}}_{3}$ is mapped as a function of temperature for the first time. The spin dynamics of the lower boundary and the excitation continuum evolve quite differently. Moreover, the dimerization of the lattice produces a sharp excitation in the lower energy boundary at the edge of the Brillouin zone, as well as the well known spin-gap opening at the zone center.
TL;DR: In this article, the competition between magnetic order and valence bond order in a two-dimensional frustrated Heisenberg model was studied and it was shown that the transition between the two types of order is first order.
Abstract: We study the competition between magnetic order and valence bond order in a two-dimensional (2D) frustrated Heisenberg model introduced some time ago by Shastry and Sutherland (Physica B, 108 (1981) 1069) for which a configuration of dimers is known to be the ground state in a certain range of parameters. Using exact diagonalization of small clusters, linear spin wave theory and Schwinger boson mean-field theory, we argue that the transition between the two types of order is first order, and that it takes place inside the domain where magnetic long-range order is stable with respect to quantum fluctuations.
TL;DR: Magnetization, transport and inelastic neutron scattering experiments were performed on single crystals of the half metallic ferromagnet NiMnSb as mentioned in this paper, where magnetic behavior seems to evolve from Heisenberg-like at low energies and low temperatures to itinerant magnetism at high temperatures and high excitation energies.
TL;DR: In this article, the influence of the finite conductivity on spin waves in metallic ferromagnetic films is explored. But the authors consider propagation perpendicular to the magnetization, which is parallel to the surface, and wavelengths sufficiently long that the effect of exchange may be ignored.
Abstract: We explore the influence of the finite conductivity on spin waves in metallic ferromagnetic films. We consider propagation perpendicular to the magnetization, which is parallel to the surface, and wavelengths sufficiently long that the influence of exchange may be ignored. Precession of the magnetization induces eddy currents which damp the spin waves, and also renormalize the dispersion relation of the Damon-Eshbach mode encountered in this geometry. We provide analytic formulas which describe these effects, in various limits. Studies through use of a Green's-function method explore the influence of the conductivity on the spectrum of spin fluctuations, in various wavelength regimes. \textcopyright{} 1996 The American Physical Society.
TL;DR: Spin gap behavior of CaV4O9 is studied by including the effects of frustrating magnetic interactions and lattice distortions and its effect on the uniform susceptibility and the spin gap are explored.
Abstract: Spin gap behavior of CaV4O9 is studied by including the effects of frustrating magnetic interactions and lattice distortions. The spectrum of triplet excitations is calculated for a Heisenberg model on the 1/5-depleted square lattice. In the spin gap phase, the location of the minima of the spectrum in the Brillouin zone is found to depend nontrivially on the exchange parameters. Experimental consequences of the temperature-dependent lattice distortion including its effect on the uniform susceptibility and the spin gap are explored.
TL;DR: In this paper, a method of calculating the time correlation functions for electron spin is proposed, based on solving the timedependent Schrodinger equation for a spin Hamiltonian that contains a term varying randomly in discrete time steps.
Abstract: A method of calculating the time correlation functions for electron spin is proposed, based on solving the time‐dependent Schrodinger equation for a spin Hamiltonian that contains a term varying randomly in discrete time steps. It is applied to the study of electron spin relaxation in aqueous solution of nickel(II) ions with S=1. The random term in the spin Hamiltonian in this case is the zero‐field splitting (ZFS) interaction. The method is evaluated by an application to a model system (the pseudorotation model) for which an analytical solution to the electron spin relaxation problem is known. The same method is then employed to study the electron and nuclear spin dynamics in a system where the time variation of the zero‐field splitting is obtained by a combination of ab initio quantum chemistry and molecular dynamics simulations.
TL;DR: The dynamical properties of intrinsic localized spin-wave modes in perfect antiferromagneticchains of classical spins with on-site easy-axis anisotropy with ILSM’s of odd parity below the plane-wave magnon frequency band are investigated.
Abstract: ~Received 15 August 1996!The dynamical properties of intrinsic localized spin-wave modes ~ILSM’s! in perfect antiferromagneticchains of classical spins with on-site easy-axis anisotropy are investigated. Only ILSM’s of odd parity existbelow the plane-wave magnon frequency band. The degree of localization increases as either the maximumspin deviation or the ratio of the anisotropy constant to the exchange coupling constant,
TL;DR: In this paper, a Green function technique is used to study the anharmonic spin-phonon and phonon phonon interaction effects on optical phonon modes and spin-wave excitations in ferromagnetic semiconductors.
Abstract: A Green function technique is used to study the anharmonic spin - phonon and phonon - phonon interaction effects on optical phonon modes and spin - wave excitations in ferromagnetic semiconductors. The cubic spinels have been investigated because the magnetostriction of these compounds is small and the direct contribution of spin ordering to the phonon modes can be clearly observed. The phonon and spin-wave energy and damping are evaluated for the first time beyond the random-phase approximation. The temperature dependence of these quantities is discussed and is found to be in good agreement with the experimental data.
TL;DR: In this article, the authors explore a microscopic model for spin waves in Co/CoO layered structures which can explain such an effect and show that the spin-wave frequency increases as either the anisotropy or interface exchange is increased.
Abstract: Recent experiments in Co/CoO layered structures have shown a huge effect where the frequency of the lowest spin wave in the ferromagnetic Co has been doubled, apparently due to the interaction with antiferromagnetic CoO. We explore a microscopic model for spin waves in such coupled structures which can explain such an effect. In this model a magnetic material with a significant anisotropy is exchange coupled to a different magnetic material with minimal anisotropy. The shift in the spin-wave frequency increases as either the anisotropy or interface exchange is increased. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this paper, the dispersion equation for the region where the spin-wave wavelength crosses the corrugation periodicity is derived for different types of corrugations and the influence of spinwave propagation losses on dispersion characteristics is discussed.
Book•
01 Jan 1996
TL;DR: In this paper, the authors present a review of nonlinear effects and their applications in different Physcial Systems, including spin wave dynamics and spin wave instability in planar Microwave Ferrite Devices.
Abstract: I: Classical and Novel Nonlinear Effects, Applications in Different Physcial Systems. 1. Notes on the Problem of Magnetization Reversal R. Arias, et al. 2. An Overview of Nonlinear Microwave and Millimeter Wave Generation in Magnetic, Acoustic and Electromagnetic Distributed Nonlinear Physical Systems M. Dragoman, D. Dragoman. 3. Inhomogeneous Internal Field Distribution in Planar Microwave Ferrite Devices M. Parda-Horvath, Guobao Zheng. 4. Design of Nonlinear Transmission Lines: GaAs and Magnetic Film Devices R. Marcelli, et al. 5. Nonlinear Dynamics of Optical Solitons S. Wabnitz. II: Spin Wave Instabilities. 6. Theory of Spin-Wave Interactions in Heisenberg Ferromagnetic Thin Films M.G. Cottam, N.J. Zhu. 7. Kinetic Instability and Bose Condensation of Magnons - The Sources of Controlled Microwave Emission from Magnetic Crystals G.A. Melkov, A.Yu. Taranenko. 8. Exchange Spin Waves in Nonuniform Films of Yttrium Ion Garnet A.G. Temiryazev, et al. 9. Parametric Instability of Spin Waves in Ferromagnets under a Spatially Localized Longitudinal Magnetic Pump Field Yu.V. Gulyaev, et al. 10. Spatial Nonuniformity and Spin Wave Turbulence in Antiferromagnet A.I. Smirnov. III: Solitons and Chaos. 11. Microwave Solitons in Magnetic Media: A Review of Fundamental Properties A.D. Boardman, et al. 12. Soliton-like Packets of Parametrically Coupled Spin Waves A.F. Popkov, et al. 13. Macroscopic Quantum Tunneling of Solitons in Ultrathin Films A.K. Zvezdin, V.V. Dobrovitski. 14. Controlling Chaos in Thin YIG Films at Microwave Frequencies D.W. Peterman, P.E. Wigen. 15. Suppressing and Controlling Chaos in Spin-Wave Instabilities T. Bernard, et al. IV: Magneto-Optic Interaction: Nonlinear Effects and Devices. 16. Applications of Magnetic Garnet Films in Optical Communication H. Dotsch, et al. 17. Interactions between Optical Guided Modes and Nonlinear Magnetostatic Waves D.D. Stancil, A. Prabhakar. 18. Integrated Magnetooptic Devices with Applications to RF Signal Processing and Communications C.S. Tsai.
TL;DR: The dispersion in CrSb is found to rise very steeply as a function of q, and a gap in the excitation spectrum occurs at q = 0.The spin-wave dispersion relations in the ferromagnet MnSb, and the antiferromagnets CrSB, have been measured, by neutron inelastic scattering, along high-symmetry directions in reciprocal space, as afunction of temperature.
Abstract: The spin-wave dispersion relations in the ferromagnet MnSb, and the antiferromagnet CrSb, have been measured, by neutron inelastic scattering, along high-symmetry directions in reciprocal space, as a function of temperature. The effect of composition is discussed. The dispersion in CrSb is found to rise very steeply as a function of q, and a gap in the excitation spectrum occurs at q = 0. The results for these itinerant electron magnetic materials are compared with previous experimental and theoretical work.
TL;DR: In this article, the results of a detailed experimental investigation of the magnetic excitations in the spin-Heisenberg antiferromagnet were presented and two possible sets of exchange paths were deduced, both of which provided good fits to the data.
Abstract: In this paper we present the results of a detailed experimental investigation of the magnetic excitations in the spin- Heisenberg antiferromagnet . Inelastic neutron scattering measurements made using a triple-axis spectrometer were performed in the low-temperature ordered phase and also briefly in the high-temperature phase at Brookhaven National Laboratory. The excitations in the ordered phase are compared to a spin-wave model and two possible sets of exchange paths are deduced, both of which provide good fits to the data. In both models consists of weakly coupled alternating one-dimensional chains running in the [2,-1,0] direction. A calculation of the spin-wave intensities was also performed using the fitted exchange constants and agreement was found with the observed intensities. In the ordered phase, has an energy gap at the zone centre and the excitations are well defined. Above the transition temperature constant-wavevector scans at the antiferromagnetic lattice points suggest the existence of a continuum of excitations.