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Showing papers on "Spin wave published in 2013"


Journal ArticleDOI
TL;DR: In this article, the experimental characterization of spin Hall effects in metallic systems is presented, and the advantages and disadvantages of complimentary measurement techniques are discussed and in addition an outlook of the possible impact on applications is presented.
Abstract: Spin Hall effects convert charge currents into spin currents and vice versa even in nonmagnetic conductors due to spin orbit coupling. This enables spin Hall effects to be utilized both for the generation and detection of spin currents and magnetization dynamics. This paper reviews the experimental characterization of these effects in metallic systems, which have so far shown the highest efficiency in using spin Hall effects for charge-to-spin interconversion. The advantages and disadvantages of complimentary measurement techniques are discussed and in addition an outlook of the possible impact on applications is presented.

885 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied the constraints imposed by the existence of a single higher spin conserved current on a three-dimensional conformal field theory and showed that the correlation functions of the stress tensor and the conserved currents are equal to those of a free field theory.
Abstract: We study the constraints imposed by the existence of a single higher spin conserved current on a three-dimensional conformal field theory (CFT). A single higher spin conserved current implies the existence of an infinite number of higher spin conserved currents. The correlation functions of the stress tensor and the conserved currents are then shown to be equal to those of a free field theory. Namely a theory of N free bosons or free fermions. This is an extension of the Coleman–Mandula theorem to CFT’s, which do not have a conventional S-matrix. We also briefly discuss the case where the higher spin symmetries are ‘slightly’ broken.This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’.

578 citations


Journal ArticleDOI
03 Oct 2013-Nature
TL;DR: In situ correlation measurements are used to observe two-magnon bound states directly in a one-dimensional Heisenberg spin chain comprising ultracold bosonic atoms in an optical lattice and determine the decay time of bound magnons.
Abstract: The existence of bound states of elementary spin waves (magnons) in one-dimensional quantum magnets was predicted almost 80 years ago. Identifying signatures of magnon bound states has so far remained the subject of intense theoretical research and their detection has proved challenging for experiments. Ultracold atoms offer an ideal setting in which to find such bound states by tracking the spin dynamics with single-spin and single-site resolution, following a local excitation. Here we use in situ correlation measurements to observe two-magnon bound states directly in a one-dimensional Heisenberg spin chain comprising ultracold bosonic atoms in an optical lattice. We observe the quantum dynamics of free and bound magnon states through time-resolved measurements of two spin impurities. The increased effective mass of the compound magnon state results in slower spin dynamics as compared to single-magnon excitations. We also determine the decay time of bound magnons, which is probably limited by scattering on thermal fluctuations in the system. Our results provide a new way of studying fundamental properties of quantum magnets and, more generally, properties of interacting impurities in quantum many-body systems.

402 citations


Journal ArticleDOI
TL;DR: The phase diagram of spin-orbit Mott insulators on a honeycomb lattice is explored, within the Kitaev-Heisenberg model extended to its full parameter space, and Zigzag-type magnetic order is found to occupy a large part of the phase diagram.
Abstract: We explore the phase diagram of spin-orbit Mott insulators on a honeycomb lattice, within the Kitaev-Heisenberg model extended to its full parameter space. Zigzag-type magnetic order is found to occupy a large part of the phase diagram of the model, and its physical origin is explained as due to interorbital t(2g)-e(g) hopping. The magnetic susceptibility, spin wave spectra, and zigzag order parameter are calculated and compared to the experimental data, obtaining thereby the spin coupling constants in Na(2)IrO(3) and Li(2)IrO(3).

376 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a topological magnonic crystal which provides protected chiral edge modes for magnetostatic spin waves, which implements novel fault-tolerant spintronic devices.
Abstract: Topological phases have been explored in various fields in physics such as spintronics, photonics, liquid helium, correlated electron system, and cold-atomic system. This leads to the recent foundation of emerging materials such as topological band insulators, topological photonic crystals, and topological superconductors/superfluid. In this paper, we propose a topological magnonic crystal which provides protected chiral edge modes for magnetostatic spin waves. Based on a linearized Landau-Lifshitz equation, we show that a magnonic crystal with the dipolar interaction acquires a spin-wave volume-mode band with nonzero Chern integer. We argue that such magnonic systems are accompanied by the same integer numbers of chiral spin-wave edge modes within a band gap for the volume-mode bands. In these edge modes, the spin wave propagates in a unidirectional manner without being scattered backward, which implements novel fault-tolerant spintronic devices.

337 citations


Journal ArticleDOI
TL;DR: It is shown that the spin orientation of a transition-metal magnetic ion can be easily explained by considering its split d-block levels as unperturbed states with the spin-orbit coupling as perturbation, and that the DM exchange between adjacent spin sites can become comparable in strength to the Heisenberg spin exchange when the two spin sites are not chemically equivalent.
Abstract: The magnetic energy levels of a given magnetic solid are closely packed in energy because the interactions between magnetic ions are weak. Thus, in describing its magnetic properties, one needs to generate its magnetic energy spectrum by employing an appropriate spin Hamiltonian. In this review article we discuss how to determine and specify a necessary spin Hamiltonian in terms of first principles electronic structure calculations on the basis of energy-mapping analysis and briefly survey important concepts and phenomena that one encounters in reading the current literature on magnetic solids. Our discussion is given on a qualitative level from the perspective of magnetic energy levels and electronic structures. The spin Hamiltonian appropriate for a magnetic system should be based on its spin lattice, i.e., the repeat pattern of its strong magnetic bonds (strong spin exchange paths), which requires one to evaluate its Heisenberg spin exchanges on the basis of energy-mapping analysis. Other weaker energy terms such as Dzyaloshinskii–Moriya (DM) spin exchange and magnetocrystalline anisotropy energies, which a spin Hamiltonian must include in certain cases, can also be evaluated by performing energy-mapping analysis. We show that the spin orientation of a transition-metal magnetic ion can be easily explained by considering its split d-block levels as unperturbed states with the spin–orbit coupling (SOC) as perturbation, that the DM exchange between adjacent spin sites can become comparable in strength to the Heisenberg spin exchange when the two spin sites are not chemically equivalent, and that the DM interaction between rare-earth and transition-metal cations is governed largely by the magnetic orbitals of the rare-earth cation.

298 citations


Journal ArticleDOI
TL;DR: The experimental results fully support present, exclusively spin current-based, theoretical models using a single set of plausible parameters for spin mixing conductance, spin Hall angle, and spin diffusion length.
Abstract: We perform a quantitative, comparative study of the spin pumping, spin Seebeck, and spin Hall magnetoresistance effects, all detected via the inverse spin Hall effect in a series of over 20??yttrium???iron?garnet/Pt samples. Our experimental results fully support present, exclusively spin current-based, theoretical models using a single set of plausible parameters for spin mixing conductance, spin Hall angle, and spin diffusion length. Our findings establish the purely spintronic nature of the aforementioned effects and provide a quantitative description, in particular, of the spin Seebeck effect.

267 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the interfacial Dzyaloshinskii-Moriya interaction leads to non-reciprocal spin-wave propagation, i.e., different properties for spin waves propagating in opposite directions.
Abstract: In ferromagnetic thin films, broken inversion symmetry and spin-orbit coupling give rise to interfacial Dzyaloshinskii-Moriya interactions. Analytic expressions for spin-wave properties show that the interfacial Dzyaloshinskii-Moriya interaction leads to nonreciprocal spin-wave propagation, i.e., different properties for spin waves propagating in opposite directions. In favorable situations, it can increase the spin-wave attenuation length. Comparing measured spin-wave properties in ferromagnet/normal metal bilayers and other artificial layered structures with these calculations could provide a useful characterization of the interfacial Dzyaloshinskii-Moriya interactions.

262 citations


Journal ArticleDOI
TL;DR: Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. as discussed by the authors has been shown to correlate well with the increase of the Gilbert damping when decreasing thickness of YIG.
Abstract: High quality nanometer-thick (20 nm, 7 nm and 4 nm) epitaxial YIG films have been grown on GGG substrates using pulsed laser deposition. The Gilbert damping coefficient for the 20 nm thick films is 2.3 x 10-4 which is the lowest value reported for sub-micrometric thick films. We demonstrate Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. The amplitude and the lineshape of the ISHE voltage correlate well to the increase of the Gilbert damping when decreasing thickness of YIG. Spin Hall effect based loss-compensation experiments have been conducted but no change in the magnetization dynamics could be detected.

211 citations


Journal ArticleDOI
TL;DR: Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. as mentioned in this paper has been shown to correlate well with the increase of the Gilbert damping when decreasing thickness of YIG.
Abstract: High quality nanometer-thick (20 nm, 7 nm, and 4 nm) epitaxial Yttrium Iron Garnet (YIG) films have been grown on gadolinium gallium garnet substrates using pulsed laser deposition. The Gilbert damping coefficient for the 20 nm thick films is 2.3 × 10−4 which is the lowest value reported for sub-micrometric thick films. We demonstrate Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. The amplitude and the lineshape of the ISHE voltage correlate well to the increase of the Gilbert damping when decreasing thickness of YIG. Spin Hall effect based loss-compensation experiments have been conducted but no change in the magnetization dynamics could be detected.

198 citations


Journal ArticleDOI
TL;DR: Microwave spectroscopy was utilized to study the magnetization oscillations locally induced in a Permalloy film by a pure spin current, which is generated due to the spin Hall effect in an adjacent Pt layer, indicating that the oscillation forms a self-localized nonpropagating spin-wave soliton.
Abstract: We utilized microwave spectroscopy to study the magnetization oscillations locally induced in a Permalloy film by a pure spin current, which is generated due to the spin Hall effect in an adjacent Pt layer. The oscillation frequency is lower than the ferromagnetic resonance of Permalloy, indicating that the oscillation forms a self-localized nonpropagating spin-wave soliton. At cryogenic temperatures, the spectral characteristics are remarkably similar to the traditional spin-torque nano-oscillators driven by spin-polarized currents. However, the linewidth of the oscillation increases exponentially with temperature and an additional peak appears in the spectrum below the ferromagnetic resonance, suggesting that the spectral characteristics are determined by interplay between two localized dynamical states.


Journal ArticleDOI
TL;DR: The magnonic grating coupler is found to be more versatile compared with gratings in photonics and plasmonics, and allows one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.
Abstract: Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.

Journal ArticleDOI
TL;DR: The experimental data reveal that the nonreciprocity of magnetostatic surface spin wave can be tuned by the bias magnetic field and engineering of the device structure could result in a high nonrecIProcity factor for spin wave logic applications.
Abstract: The utilization of spin waves as eigenmodes of the magnetization dynamics for information processing and communication has been widely explored recently due to its high operational speed with low power consumption and possible applications for quantum computations. Previous proposals of spin wave Mach-Zehnder devices were based on the spin wave phase, a delicate entity which can be easily disrupted. Here, we propose a complete logic system based on the spin wave amplitude utilizing the nonreciprocal spin wave behavior excited by microstrip antennas. The experimental data reveal that the nonreciprocity of magnetostatic surface spin wave can be tuned by the bias magnetic field. Furthermore, engineering of the device structure could result in a high nonreciprocity factor for spin wave logic applications.

Journal ArticleDOI
TL;DR: In this article, the authors show that two-dimensional periodic allay of ferromagnetic particles coupled with magnetic dipole-dipole interactions supports chiral spin-wave edge modes, when subjected under the magnetic field applied perpendicular to the plane.
Abstract: Based on a linearized Landau-Lifshitz equation, we show that two-dimensional periodic allay of ferromagnetic particles coupled with magnetic dipole-dipole interactions supports chiral spin-wave edge modes, when subjected under the magnetic field applied perpendicular to the plane. The mode propagates along a one-dimensional boundary of the system in a unidirectional way and it always has a chiral dispersion within a band gap for spin-wave volume modes. Contrary to the well-known Damon-Eshbach surface mode, the sense of the rotation depends not only on the direction of the field but also on the strength of the field; its chiral direction is generally determined by the sum of the so-called Chern integers defined for spin-wave volume modes below the band gap. Using simple tight-binding descriptions, we explain how the magnetic dipolar interaction endows spin-wave volume modes with nonzero Chern integers and how their values will be changed by the field.

Journal ArticleDOI
TL;DR: In this article, the spin diffusion length of permalloy/Pt bilayers was determined via spin pumping and spin Hall effect in a broadband approach, and the authors obtained a spin diffusion size of ∼1.2 nm at room temperature and ∼ 1.6 nm at 8 k K.
Abstract: The spin diffusion length of Pt at room temperature and at 8 K is experimentally determined via spin pumping and spin Hall effect in permalloy/Pt bilayers. Voltages generated during excitation of ferromagnetic resonance from the inverse spin Hall effect and anisotropic magnetoresistance effect were investigated with a broadband approach. Varying the Pt layer thickness gives rise to an evolution of the voltage line shape due to the superposition of the above two effects. By studying the ratio of the two voltage components with the Pt layer thickness, the spin diffusion length of Pt can be directly extracted. We obtain a spin diffusion length of ∼1.2 nm at room temperature and ∼1.6 nm at 8 K.

Journal ArticleDOI
TL;DR: A theoretical overview of the phenomenon of spontaneous magnon decays in quantum antiferromagnets is presented in this article, where the intrinsic zero-temperature damping of magnons in quantum spin systems is a fascinating many-body effect.
Abstract: A theoretical overview of the phenomenon of spontaneous magnon decays in quantum antiferromagnets is presented. The intrinsic zero-temperature damping of magnons in quantum spin systems is a fascinating many-body effect, which has recently attracted significant attention in view of its possible observation in neutron-scattering experiments. An introduction to the theory of magnon interactions and a discussion of necessary symmetry and kinematic conditions for spontaneous decays are provided. Various parallels with the decays of anharmonic phonons and excitations in superfluid $^{4}\mathrm{He}$ are extensively used. Three principal cases of spontaneous magnon decays are considered: field-induced decays in Heisenberg antiferromagnets, zero-field decays in spiral antiferromagnets, and triplon decays in quantum-disordered magnets. Analytical results are compared with available numerical data and prospective materials for experimental observation of the decay-related effects are briefly discussed.

Journal ArticleDOI
TL;DR: The spin-wave dispersion relation is asymmetric with respect to wave vector inversion for a variety of ferromagnetic films with Dzyaloshinskii-Moriya interactions and different crystallographic classes and it is predicted that, for non-zero wave vectors, the resonance frequency and resonance field can increase or decrease depending on thespin-wave vector orientation.
Abstract: We have developed a theory that describes the spin-wave spectra of ferromagnetic films with Dzyaloshinskii–Moriya interactions. In agreement with recent experiments (Zakeri et al 2010 Phys. Rev. Lett. 104 137203), we demonstrate that the spin-wave dispersion relation is asymmetric with respect to wave vector inversion for a variety of ferromagnetic films with Dzyaloshinskii–Moriya interactions and different crystallographic classes. It is also predicted that, for non-zero wave vectors, the resonance frequency and resonance field can increase or decrease depending on the spin-wave vector orientation. We provide explicit formulas for the spin-wave dispersion relation and its asymmetry, as well as for the dynamic susceptibility for a film under microwave excitation, that can be used to understand ferromagnetic resonance as well as Brillouin light scattering experiments in these classes of magnetic thin films.

Journal ArticleDOI
TL;DR: In this article, the authors present an experimental study of spin-wave excitation and propagation in microstructured waveguides patterned from a 100 nm thick yttrium iron garnet (YIG)/platinum bilayer.
Abstract: We present an experimental study of spin-wave excitation and propagation in microstructured waveguides patterned from a 100 nm thick yttrium iron garnet (YIG)/platinum (Pt) bilayer. The life time of the spin waves is found to be more than an order of magnitude higher than in comparably sized metallic structures despite the fact that the Pt capping enhances the Gilbert damping. Utilizing microfocus Brillouin light scattering spectroscopy, we reveal the spin-wave mode structure for different excitation frequencies. An exponential spin-wave amplitude decay length of 31 {\mu}m is observed which is a significant step towards low damping, insulator based micro-magnonics.

Journal ArticleDOI
TL;DR: A magnetically controllable heat flow caused by a spin-wave current is shown, directly applicable to the fabrication of a heat-flow controller.
Abstract: The dissipation of heat towards cooler regions of a thermodynamic system is a ubiquitous phenomenon. It is now shown that collective excitations known as spin waves can be used to control the flow of heat in a ferrimagnet consisting of Y3Fe5O12.

Journal ArticleDOI
TL;DR: In this article, the spin diffusion equation was extended to include spin-rotation coupling, and it was shown that larger spin currents can be obtained in materials with longer spin lifetimes.
Abstract: Spin-rotation coupling, which is responsible for angular momentum conversion between the electron spin and rotational deformations of elastic media, is exploited for generating spin current. This method requires neither magnetic moments nor spin-orbit interaction. The spin current generated in nonmagnets is calculated in the presence of surface acoustic waves. We solve the spin diffusion equation, extended to include spin-rotation coupling, and find that larger spin currents can be obtained in materials with longer spin lifetimes. Spin accumulation induced on the surface is predicted to be detectable by time-resolved Kerr spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, the thermally induced spin angular momentum transfer between a paramagnetic metal and a ferromagnetic insulator is studied theoretically based on the stochastic Landau-Lifshitz-Gilbert (LLG) phenomenology.
Abstract: Thermal-bias-induced spin angular momentum transfer between a paramagnetic metal and ferromagnetic insulator is studied theoretically based on the stochastic Landau-Lifshitz-Gilbert (LLG) phenomenology. Magnons in the ferromagnet establish a nonequilibrium steady state by equilibrating with phonons via bulk Gilbert damping and electrons in the paramagnet via spin pumping, according to the fluctuation-dissipation theorem. Subthermal magnons and the associated spin currents are treated classically, while the appropriate quantum crossover is imposed on high-frequency magnetic fluctuations. We identify several length scales in the ferromagnet, which govern qualitative changes in the dependence of the thermally induced spin current on the magnetic film thickness.

Journal ArticleDOI
TL;DR: The dependence of spin pumping efficiency and the spin mixing conductance on the surface processing of yttrium iron garnet (YIG) before the platinum (Pt) deposition has been investigated quantitatively.
Abstract: The dependence of the spin pumping efficiency and the spin mixing conductance on the surface processing of yttrium iron garnet (YIG) before the platinum (Pt) deposition has been investigated quantitatively. The ferromagnetic resonance driven spin pumping injects a spin polarized current into the Pt layer, which is transformed into an electromotive force by the inverse spin Hall effect. Our experiments show that the spin pumping effect indeed strongly depends on the YIG/Pt interface condition. We measure an enhancement of the inverse spin Hall voltage and the spin mixing conductance of more than two orders of magnitude with improved sample preparation.

Journal ArticleDOI
TL;DR: Thermally induced domain wall motion in a magnetic insulator was observed using spatiotemporally resolved polar magneto-optical Kerr effect microscopy, which suggests the utility of magnonic spin transfer torque for controlling magnetization dynamics.
Abstract: Thermally induced domain wall motion in a magnetic insulator was observed using spatiotemporally resolved polar magneto-optical Kerr effect microscopy. The following results were found: (i) the domain wall moves towards hot regime; (ii) a threshold temperature gradient ($5\text{ }\text{ }\mathrm{K}/\mathrm{mm}$), i.e., a minimal temperature gradient required to induce domain wall motion; (iii) a finite domain wall velocity outside of the region with a temperature gradient, slowly decreasing as a function of distance, which is interpreted to result from the penetration of a magnonic current into the constant temperature region; and (iv) a linear dependence of the average domain wall velocity on temperature gradient, beyond a threshold thermal bias. Our observations can be qualitatively explained using a magnonic spin transfer torque mechanism, which suggests the utility of magnonic spin transfer torque for controlling magnetization dynamics.

Journal ArticleDOI
TL;DR: It is shown how Skyrmions can be created by increasing the current in the magnetic spiral state by constructing a dynamic phase diagram for a chiral magnet with a current.
Abstract: We study the dynamics of Skyrmions in chiral magnets in the presence of a spin polarized current. The motion of Skyrmions in the ferromagnetic background excites spin waves and contributes to additional damping. At a large current, the spin wave spectrum becomes gapless and Skyrmions are created dynamically from the ferromagnetic state. At an even higher current, these Skyrmions are strongly deformed due to the damping and become unstable at a threshold current, leading to a chiral liquid. We show how Skyrmions can be created by increasing the current in the magnetic spiral state. We then construct a dynamic phase diagram for a chiral magnet with a current. The instability transitions between different states can be observed as experimentally clear signatures in the transport measurements, such as jumps and hysteresis.

Journal ArticleDOI
Abstract: We theoretically investigate the spin Seebeck effect (SSE) in antiferromagnets and ferrimagnets, and show that the SSE vanishes in antiferromagnets but survives in ferrimagnets even at the magnetization compensation point despite the absence of its saturation magnetization. The nonvanishing SSE in ferrimagnets stems from two nondegenerate magnons. We demonstrate that the magnitude of the SSE in ferrimagnets is unchanged across the magnetization compensation point.

Journal ArticleDOI
TL;DR: Measurements in a magnetic insulator subject to a thermal gradient indicate that if the transverse spin Seebeck effect is caused by a temperature difference between the magnon and phonon baths, it must be the case that theMagnon temperature is spectrally nonuniform.
Abstract: We present spatially resolved measurements of the magnon temperature in a magnetic insulator subject to a thermal gradient. Our data reveal an unexpectedly close correspondence between the spatial dependencies of the exchange magnon and phonon temperatures. These results indicate that if--as is currently thought--the transverse spin Seebeck effect is caused by a temperature difference between the magnon and phonon baths, it must be the case that the magnon temperature is spectrally nonuniform and that the effect is driven by the sparsely populated dipolar region of the magnon spectrum.

Journal ArticleDOI
TL;DR: In this article, the authors measured spin-transport in nonferromagnetic (NM) metallic multilayers from the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10 thin film.
Abstract: We measured spin-transport in nonferromagnetic (NM) metallic multilayers from the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10 thin film. The multilayer stack consisted of NM1/NM2/Co90Fe10(2 nm)/NM2/NM3 with varying NM materials and thicknesses. Using conventional theory for one-dimensional diffusive spin transport in metals, we show that the effective damping due to spin pumping can be strongly affected by the spin transport properties of each NM in the multilayer, which permits the use of damping measurements to accurately determine the spin transport properties of the various NM layers in the full five-layer stack. We find that due to its high electrical resistivity, amorphous Ta is a poor spin conductor, in spite of a short spin-diffusion length of 1.0 nm, and that Pt is an excellent spin conductor by virtue of its low electrical resistivity and a spin diffusion length of only 0.5 nm. Spin Hall effect measurements may have underestimated the spin Hall angle in Pt by assumi...

Journal ArticleDOI
TL;DR: In this paper, a standard micromagnetic problem, of a nanostripe of permalloy, was proposed and the magnetization dynamics and the extraction features from simulations were described.
Abstract: In this paper, we propose a standard micromagnetic problem, of a nanostripe of permalloy. We study the magnetization dynamics and describe methods of extracting features from simulations. Spin wave dispersion curves, relating frequency and wave vector, are obtained for wave propagation in different directions relative to the axis of the waveguide and the external applied field. Simulation results using both finite element (Nmag) and finite difference (OOMMF) methods are compared against analytic results, for different ranges of the wave vector.

Journal ArticleDOI
TL;DR: An all-optical experiment long utilized to image phonons excited by ultrashort optical pulses has been applied to a magnetic sample and an X-shaped pattern formed by propagating spin waves is observed.
Abstract: An all-optical experiment long utilized to image phonons excited by ultrashort optical pulses has been applied to a magnetic sample. In addition to circular ripples due to surface acoustic waves, we observe an X-shaped pattern formed by propagating spin waves. The emission of spin waves from the optical pulse epicenter in the form of collimated beams is qualitatively reproduced by micromagnetic simulations. We explain the observed pattern in terms of the group velocity distribution of Damon-Eshbach magnetostatic spin waves in the reciprocal space and the wave vector spectrum of the focused ultrafast laser pulse.