Showing papers on "Spin wave published in 2022"
TL;DR: In this paper, the spin-orbit excitons observed at 20-28 meV in both compounds strongly support the idea that Co2+ ions of both compounds have a spin-orbital entangled Jeff=1/2 state.
Abstract: Finding new materials with antiferromagnetic (AFM) Kitaev interaction is an urgent issue for quantum magnetism research. We conclude that Na3Co2SbO6 and Na2Co2TeO6 are new honeycomb cobalt-based systems with AFM Kitaev interaction by carrying out inelastic neutron scattering experiments and subsequent analysis. The spin-orbit excitons observed at 20-28 meV in both compounds strongly support the idea that Co2+ ions of both compounds have a spin-orbital entangled Jeff=1/2 state. Furthermore, we found that a generalized Kitaev-Heisenberg Hamiltonian can describe the spin-wave excitations of both compounds with additional 3rd nearest-neighbor interaction. Our best-fit parameters show significant AFM Kitaev terms and off-diagonal symmetric anisotropy terms of a similar magnitude in both compounds. We also found a strong magnon-damping effect at the higher energy part of the spin waves, entirely consistent with observations in other Kitaev magnets. Our work suggests Na3Co2SbO6 and Na2Co2TeO6 as rare examples of the AFM Kitaev magnets based on the systematic studies of the spin waves and analysis.
34 citations
TL;DR: In this article , the Bernoulli sub-equation (BSE), a novel Kudryashov (NKud), and He's homotopy perturbation (He's HP) were used to check the solutions.
Abstract: In this study, we investigate the solitary wave solutions for the (2+1)-dimensional Heisenberg ferromagnetic spin chain (HFSC). New solitary wave solutions are generated and checked using the Bernoulli sub-equation (BSE), a novel Kudryashov (NKud), and He’s homotopy perturbation (He’s HP). One may learn about solitary waves by looking at polar, contour, two-dimensional, or three-dimensional charts. Our research is original because it contrasts with what has already been done. Mathematica software 13.1 is utilized for checking the computational techniques solutions’ accuracy by putting them back into the original model.
15 citations
TL;DR: In this paper , a tripartite coupling between phonons, magnons, and photons in a periodic array of elliptical magnetostrictive nanomagnets delineated on a piezoelectric substrate to form a 2D two-phase multiferroic crystal is investigated.
Abstract: Tripartite coupling between phonons, magnons, and photons in a periodic array of elliptical magnetostrictive nanomagnets delineated on a piezoelectric substrate to form a 2D two‐phase multiferroic crystal is investigated. Surface acoustic waves (SAW) (phonons) of 5–35 GHz frequency launched into the substrate cause the magnetizations of the nanomagnets to precess at the frequency of the wave, giving rise to confined spin‐wave modes (magnons) within the nanomagnets. The spin waves, in turn, radiate electromagnetic waves (photons) into the surrounding space at the SAW frequency. Here, the phonons couple into magnons, which then couple into photons. This tripartite phonon‐magnon‐photon coupling is thus exploited to implement an extreme sub‐wavelength electromagnetic antenna whose measured radiation efficiency and antenna gain exceed the approximate theoretical limits for traditional antennas of the same dimensions by more than two orders of magnitude at some frequencies. Micro‐magnetic simulations are in excellent agreement with experimental observations and provide insight into the spin‐wave modes that couple into radiating electromagnetic modes to implement the antenna.
14 citations
TL;DR: In this article , the excitation of spin-current induced THz spin-waves in noncollinear bilayer structures was used to directly study optical spin currents in the time domain.
Abstract: Optically induced spin currents have proven to be useful in spintronics applications, allowing for sub-ps all-optical control of magnetization. However, the mechanism responsible for their generation is still heavily debated. Here we use the excitation of spin-current induced THz spin-waves in noncollinear bilayer structures to directly study optical spin-currents in the time domain. We measure a significant laser-fluence dependence of the spin-wave phase, which can quantitatively be explained assuming the spin current is proportional to the time derivative of the magnetization. Measurements of the absolute spin-wave phase, supported by theoretical calculations and micromagnetic simulations, suggest that a simple ballistic transport picture is sufficient to properly explain spin transport in our experiments and that the damping-like optical STT dominates THz spin-wave generation. Our findings suggest laser-induced demagnetization and spin-current generation share the same microscopic origin.
13 citations
13 citations
TL;DR: In this paper , an effective spin-transport description that treats itinerant electrons and thermal magnons on an equal footing is presented. But the authors assume that in the low-fluence limit, the magnon system remains in a quasiequilibrium, allowing a transient nonzero magnon chemical potential.
Abstract: We theoretically investigate laser-induced spin transport in metallic magnetic heterostructures using an effective spin-transport description that treats itinerant electrons and thermal magnons on an equal footing. Electron-magnon scattering is included and taken as the driving force for ultrafast demagnetization. We assume that in the low-fluence limit, the magnon system remains in a quasiequilibrium, allowing a transient nonzero magnon chemical potential. In combination with the diffusive transport equations for the itinerant electrons, the description is used to chart the full spin dynamics within the heterostructure. In agreement with recent experiments, we find that in the case the spin-current-receiving material includes an efficient spin dissipation channel, the interfacial spin current becomes directly proportional to the temporal derivative of the magnetization. Based on an analytical calculation, we discuss that other relations between the spin current and magnetization may arise in the case the spin-current-receiving material displays inefficient spin-flip scattering. Finally, we discuss the role of (interfacial) magnon transport and show that, a priori, it cannot be neglected. However, its significance strongly depends on the system parameters.
11 citations
TL;DR: In this article , the A-type antiferromagnetic order using single crystal neutron diffraction is confirmed using inelastic neutron scattering and rigorously fit the excitation modes to a spin wave model.
Abstract: CrSBr is an air‐stable two‐dimensional (2D) van der Waals semiconducting magnet with great technological promise, but its atomic‐scale magnetic interactions—crucial information for high‐frequency switching—are poorly understood. An experimental study is presented to determine the CrSBr magnetic exchange Hamiltonian and bulk magnon spectrum. The A‐type antiferromagnetic order using single crystal neutron diffraction is confirmed here. The magnon dispersions are also measured using inelastic neutron scattering and rigorously fit the excitation modes to a spin wave model. The magnon spectrum is well described by an intra‐plane ferromagnetic Heisenberg exchange model with seven nearest in‐plane exchanges. This fitted exchange Hamiltonian enables theoretical predictions of CrSBr behavior: as one example, the fitted Hamiltonian is used to predict the presence of chiral magnon edge modes with a spin‐orbit enhanced CrSBr heterostructure.
11 citations
01 Jan 2022
TL;DR: Using inelastic neutron scattering, this article studied spin wave excitations in polycrystalline CrCl$_3$ which exhibits ferromagnetic honeycomb layers with antiferromagnetic stackings along the $c$-axis.
Abstract: Two dimensional van der Waals ferromagnets with honeycomb structures are expected to host the bosonic version of Dirac particles in their magnon excitation spectra. Using inelastic neutron scattering, we study spin wave excitations in polycrystalline CrCl$_3$, which exhibits ferromagnetic honeycomb layers with antiferromagnetic stackings along the $c$-axis. For comparison, polycrystal samples of CrI$_3$ with different grain sizes are also studied. We find that the powder-averaged spin wave spectrum of CrCl$_3$ at $T$ = 2 K can be adequately explained by the two dimensional spin Hamiltonian including in-plane Heisenberg exchanges only. The observed excitation does not exhibit noticeable broadening in energy, which is in remarkable contrast to the substantial broadening observed in CrI$_3$. Based on these results, we conclude that the ferromagnetic phase of CrCl$_3$ hosts massless Dirac magnons and is thus not topological.
11 citations
TL;DR: In this article , a long-distance spin-transport in the antiferromagnetic orthoferrite YFeO 3 , where a different transport mechanism is enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields, is reported.
Abstract: Abstract In antiferromagnets, the efficient transport of spin-waves has until now only been observed in the insulating antiferromagnet hematite, where circularly (or a superposition of pairs of linearly) polarized spin-waves diffuse over long distances. Here, we report long-distance spin-transport in the antiferromagnetic orthoferrite YFeO 3 , where a different transport mechanism is enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields. The magnon decay length is shown to exceed hundreds of nanometers, in line with resonance measurements that highlight the low magnetic damping. We observe a strong anisotropy in the magnon decay lengths that we can attribute to the role of the magnon group velocity in the transport of spin-waves in antiferromagnets. This unique mode of transport identified in YFeO 3 opens up the possibility of a large and technologically relevant class of materials, i.e., canted antiferromagnets, for long-distance spin transport.
10 citations
TL;DR: In this paper , the authors investigated collective spin excitations and spin fluctuations in atomically thin MnBi2Te4 flakes using Raman spectroscopy and found magnetic fluctuations increase with reduced thickness, which may contribute to less robust magnetic order in single layers.
Abstract: Electron band topology is combined with intrinsic magnetic orders in MnBi2Te4, leading to novel quantum phases. Here we investigate collective spin excitations (i.e. magnons) and spin fluctuations in atomically thin MnBi2Te4 flakes using Raman spectroscopy. In a two-septuple layer with non-trivial topology, magnon characteristics evolve as an external magnetic field tunes the ground state through three ordered phases: antiferromagnet, canted antiferromagnet, and ferromagnet. The Raman selection rules are determined by both the crystal symmetry and magnetic order while the magnon energy is determined by different interaction terms. Using non-interacting spin-wave theory, we extract the spin-wave gap at zero magnetic field, an anisotropy energy, and interlayer exchange in bilayers. We also find magnetic fluctuations increase with reduced thickness, which may contribute to a less robust magnetic order in single layers.
10 citations
TL;DR: In this paper , the conditions for dipolar mode-hybridization, how it may be controlled, why it was not observed earlier, and how strong coupling may occur between nanomagnet bulk modes.
Abstract: Dipolar magnon-magnon coupling has long been predicted in nanopatterned artificial spin systems. However, observation of such phenomena and related collective spin-wave signatures have until recently proved elusive or been limited to low-power edge modes which are difficult to measure experimentally. Here we describe the requisite conditions for dipolar mode-hybridization, how it may be controlled, why it was not observed earlier, and how strong coupling may occur between nanomagnet bulk modes. We experimentally investigate four nanopatterned artificial spin system geometries: chevron arrays, square, staircase, and brickwork artificial spin ices. We observe significant dynamic dipolar-coupling in all systems with relative coupling strengths and avoided-crossing gaps supported by micromagnetic-simulation results. We demonstrate reconfigurable mode-hybridization regimes in each system via microstate control, and in doing so elucidate the underlying dynamics governing dynamic dipolar-coupling with implications across reconfigurable magnonics. We demonstrate that confinement of the bulk modes via edge effects plays a critical role in dipolar hybridized modes, and treating each nanoisland as a coherently precessing macro-spin or a standing spin-wave is insufficient to capture experimentally observed coupling phenomena. Finally, we present a parameter-space search detailing how coupling strength may be tuned via nanofabrication dimensions and material properties.
TL;DR: In this article , inelastic neutron scattering studies of the prototypical kagome magnetic metal FeSn were performed and it was shown that the Dirac magnon at the $K$ point remarkably occurs on the brink of a region where well-defined spin waves become unobservable.
Abstract: The kagome lattice is a fertile platform to explore topological excitations with both Fermi-Dirac and Bose-Einstein statistics. While relativistic Dirac fermions and flat bands have been discovered in the electronic structure of kagome metals, the spin excitations have received less attention. Here, we report inelastic neutron scattering studies of the prototypical kagome magnetic metal FeSn. The spectra display well-defined spin waves extending to 120 meV. Above this energy, the spin waves become progressively broadened, reflecting interactions with the Stoner continuum. Using linear spin-wave theory, we determine an effective spin Hamiltonian that reproduces the measured dispersion. This analysis indicates that the Dirac magnon at the $K$ point remarkably occurs on the brink of a region where well-defined spin waves become unobservable. Our results emphasize the influential role of itinerant carriers on the topological spin excitations of metallic kagome magnets.
TL;DR: In this paper , the existence of spin-wave solitons, dynamic localized bound states of spinwave excitations, in FePt nanoparticles was shown with time-resolved x-ray diffraction and micromagnetic modeling, and the measured soliton spin precession frequency of 0.1 THz positions this system as a platform to develop novel miniature devices.
Abstract: Magnetic nanoparticles such as FePt in the L10 phase are the bedrock of our current data storage technology. As the grains become smaller to keep up with technological demands, the superparamagnetic limit calls for materials with higher magnetocrystalline anisotropy. This, in turn, reduces the magnetic exchange length to just a few nanometers, enabling magnetic structures to be induced within the nanoparticles. Here, we describe the existence of spin-wave solitons, dynamic localized bound states of spin-wave excitations, in FePt nanoparticles. We show with time-resolved x-ray diffraction and micromagnetic modeling that spin-wave solitons of sub-10 nm sizes form out of the demagnetized state following femtosecond laser excitation. The measured soliton spin precession frequency of 0.1 THz positions this system as a platform to develop novel miniature devices.
TL;DR: In this paper , a hydrodynamic description of spin systems with global SU(2) symmetry in the ferromagnetic phase is presented, and a key signature of the collision-dominated hydrodynamics is identified, namely the magnon sound mode.
Abstract: The noninteracting magnon gas description in ferromagnets breaks down at finite magnon density where momentum-conserving collisions between magnons become important. Here we present a hydrodynamic description of spin systems with global SU(2) symmetry in the ferromagnetic phase. We identify a key signature of the collision-dominated hydrodynamic regime---a magnon sound mode---which governs dynamics at low frequencies. The magnon sound mode is an excitation of the longitudinal spin component with frequencies below the spin-wave continuum in gapped ferromagnets and can be detected with recently introduced spin qubit magnetometers. We also show that, in the presence of exchange interactions with SU(2) symmetry, the ferromagnet hosts an usual hydrodynamic regime that lacks Galilean symmetry. We show that our results are relevant to ferromagnetic insulators in a finite energy/temperature window such that dipolar and magnon--phonon interactions are negligible, as well as in recent experiments in cold atomic gases.
TL;DR: In this paper , the spin-wave asymmetry induced by the curvature is theoretically studied in thick ferromagnetic nanotubes with a vortex ground state, and the spinwave spectra are obtained using semianalytical calculations and the dynamical matrix method for thin and thick nanotsubes.
Abstract: Magnetochiral properties are enriched in curved magnetic nanostructures, in which dipole-dipole and exchange couplings are their physical sources. In such systems, direct implications are evidenced in the magnetization dynamics, where a noticeable frequency shift appears between two counterpropagating spin waves. In this paper, the spin-wave asymmetry induced by the curvature is theoretically studied in thick ferromagnetic nanotubes with a vortex ground state. The spin-wave spectra are obtained using semianalytical calculations and the dynamical matrix method for thin and thick nanotubes. Under the thickness increase, radial standing spin waves are observed at low frequencies, while the nonreciprocal properties are improved. Such standing waves exhibit a nonreciprocal spin-wave dispersion, but it is not as prominent as the asymmetry of the low-frequency in-phase modes. In the limit of small wave vectors, analytical expressions are reported for the spin-wave dispersion, where the resonance frequency, the frequency shift of two counterpropagating waves, and the critical field that destabilizes the vortex state are determined. The obtained frequency shift allows us to estimate the influence of thickness and curvature on the nonreciprocity of the spin waves. These results constitute a significant advance in the fundamental understanding of the spin-wave dynamics of ferromagnetic nanotubes, predicting new phenomena and providing expressions that are easy to interpret and that allow us, therefore, to promote the study of magnetization dynamics in curved structures.
TL;DR: In this article , the authors derived dispersion relations describing the propagation of nutation spin waves in an arbitrary direction relative to the applied magnetic field using the inertial Landau-Lifshitzitz-Gilbert equation.
Abstract: Magnetization dynamics and spin waves in ferromagnets are investigated using the inertial Landau-Lifshitz-Gilbert equation. Taking inertial magnetization dynamics into account, dispersion relations describing the propagation of nutation spin waves in an arbitrary direction relative to the applied magnetic field are derived via Maxwell's equations. It is found that the inertia of magnetization causes the hybridization of electromagnetic waves and nutation spin waves in ferromagnets, hybrid nutation spin waves emerge, and the redshift of frequencies of precession spin waves is initiated, which transforms to precession-nutation spin waves. These effects depend sharply on the direction of wave propagation relative to the applied magnetic field. Moreover, the waves propagating parallel to the applied field are circularly polarized, while the waves propagating perpendicular to that field are elliptically polarized. The characteristics of these spin nutation waves are also analyzed.
TL;DR: In this article , the authors provide a quantum theory describing mutual backaction between spin waves and spin ensembles and predict that external control of the latter enables to largely and dynamically modify spin wave properties such as propagation length.
Abstract: Spin waves are prime candidates for information processing. The recent demonstration of their coupling to dense ensembles of solid-state spins paves the way toward coherent spin wave control in a similar fashion as, e.g., slow light in optics. Here, the authors provide a quantum theory describing mutual backaction between spin waves and spin ensembles and predict that external control of the latter enables to largely and dynamically modify spin wave properties such as propagation length. They also propose localized spin ensembles as spin wave sensors able to detect even vacuum spin-wave fluctuations. These results pave the way toward nanophotonics-inspired magnonic devices and protocols.
TL;DR: In this article , a hidden quadrupolar component of the spin dynamics in antiferromagnetic S = 1 Haldane chain material Y2BaNiO5 using Ni L3-edge resonant inelastic x-ray scattering was revealed.
Abstract: The microscopic origins of emergent behaviours in condensed matter systems are encoded in their excitations. In ordinary magnetic materials, single spin-flips give rise to collective dipolar magnetic excitations called magnons. Likewise, multiple spin-flips can give rise to multipolar magnetic excitations in magnetic materials with spin S ≥ 1. Unfortunately, since most experimental probes are governed by dipolar selection rules, collective multipolar excitations have generally remained elusive. For instance, only dipolar magnetic excitations have been observed in isotropic S = 1 Haldane spin systems. Here, we unveil a hidden quadrupolar constituent of the spin dynamics in antiferromagnetic S = 1 Haldane chain material Y2BaNiO5 using Ni L3-edge resonant inelastic x-ray scattering. Our results demonstrate that pure quadrupolar magnetic excitations can be probed without direct interactions with dipolar excitations or anisotropic perturbations. Originating from on-site double spin-flip processes, the quadrupolar magnetic excitations in Y2BaNiO5 show a remarkable dual nature of collective dispersion. While one component propagates as non-interacting entities, the other behaves as a bound quadrupolar magnetic wave. This result highlights the rich and largely unexplored physics of higher-order magnetic excitations.
TL;DR: In this paper , the effects of the waveguides geometry, location of the microantennas for excitation and detection of the spin waves, and geometry of waveguide junctions on the spin wave energy and propagation efficiency are discussed.
TL;DR: In this article, the authors demonstrate that the magnon bandgap frequencies can be tuned by the application of a low-dissipative transport current and by its polarity reversal.
TL;DR: In this paper , the authors theoretically investigate the microscopic conditions for emergent non-reciprocal magnons toward unified understanding on the basis of a microscopic model analysis, and they show that the products of the Bogoliubov Hamiltonian obtained within the linear spin wave approximation is enough to obtain the momentum-space functional form and the key ingredients in the non-rewarded magnon dispersions in an analytical way even without solving the eigenvalue problems.
Abstract: We theoretically investigate the microscopic conditions for emergent nonreciprocal magnons toward unified understanding on the basis of a microscopic model analysis. We show that the products of the Bogoliubov Hamiltonian obtained within the linear spin wave approximation is enough to obtain the momentum-space functional form and the key ingredients in the nonreciprocal magnon dispersions in an analytical way even without solving the eigenvalue problems. We find that the odd order of an effective antisymmetric Dzyaloshinskii-Moriya interaction and/or the even order of an effective symmetric anisotropic interaction in the spin rotated frame can be a source of the antisymmetric dispersions. We present possible kinetic paths of magnons contributing to the antisymmetric dispersions in the one- to four-sublattice systems with the general exchange interactions. We also test the formula for both ferromagnetic and antiferromagnetic orderings in the absence of spatial inversion symmetry.
TL;DR: In this article, the effects of the waveguides geometry, location of the microantennas for excitation and detection of the spin waves, and geometry of waveguide junctions on the spin wave energy and propagation efficiency are discussed.
TL;DR: In this article , the Stern-Gerlach (SG) effect in an antiferromagnetic magnonic system is proposed, where a linearly polarized spinwave beam is deflected by a straight Dzyaloshinskii-Moriya interaction (DMI) interface into two opposite polarized spin-wave beams propagating in two discrete directions.
Abstract: The Stern–Gerlach (SG) effect is well known as the spin-dependent splitting of a beam of atoms carrying magnetic moments by a magnetic-field gradient, leading to the concept of electron spin. Antiferromagnets can accommodate two magnon modes with opposite spin polarizations, which is equivalent to the spin property of electrons. Here, we propose an all-magnonic SG effect in an antiferromagnetic magnonic system, where a linearly polarized spin-wave beam is deflected by a straight Dzyaloshinskii–Moriya interaction (DMI) interface into two opposite polarized spin-wave beams propagating in two discrete directions. Moreover, we observe bi-focusing of antiferromagnetic spin waves induced by a curved DMI interface, which can also spatially separate thermal magnons with opposite polarizations. Our findings provide a unique perspective to understand the rich phenomena associated with antiferromagnetic magnon spin and would be helpful for polarization-dependent application of antiferromagnetic spintronic devices.
TL;DR: In this paper , the authors formulated four dispersive spin-momentum equations, revealing in theory that transverse spin is locked with kinetic momentum, and in dispersive metal or magnetic materials, spin-mentum locking obeys the left-hand screw rule.
Abstract: Intrinsic spin-momentum locking is an inherent property of surface electromagnetic fields and its study has led to the discovery of phenomena such as unidirectional guided waves and photonic spin lattices. Previously, dispersion was ignored in spin-momentum locking, resulting in anomalies contradicting the apparent physical reality. Here, we formulate four dispersive spin-momentum equations, revealing in theory that transverse spin is locked with kinetic momentum. Moreover, in dispersive metal or magnetic materials spin-momentum locking obeys the left-hand screw rule. In addition to dispersion, structural features can affect substantially this locking. Remarkably, an extraordinary spin originating from coupling polarization ellipticities is uncovered that depends on the symmetry of the field modes. We further identify the properties of this spin-momentum locking with diverse photonic topological lattices by engineering their rotational symmetry akin to that in solid-state physics. The concept of spin-momentum locking based on photon flow properties translates easily to other classical wave fields.
TL;DR: In this paper, a theoretical description of magnon-phonon interactions in a multilayer structure containing a ferromagnetic thin film is presented, which is applicable to an arbitrary direction of external magnetic field and various types of acoustic waves including Rayleigh and Love surface modes.
TL;DR: In this article , a theoretical description of magnon-phonon interactions in a multilayer structure containing a ferromagnetic thin film is presented, which is applicable to an arbitrary direction of external magnetic field and various types of acoustic waves including Rayleigh and Love surface modes.
TL;DR: In this paper, the authors achieved the transition of target skyrmions with the breaking of topological protection by applying perpendicular microwave magnetic field, assisted by the excitation of breathing modes and hybridized modes.
TL;DR: In this paper , the non-Hermitian skin effect of magnetic excitation in a periodic array of magnetic nanowires that are coupled chirally via spin waves of thin magnetic films was observed.
Abstract: Non-Hermitian skin effect was observed in one-dimensional systems with short-range chiral interaction. Long-range chiral interaction mediated by traveling waves also favors the accumulation of energy, but has not yet showed non-Hermitian topology. Here we find that the strong interference brought by the wave propagation is detrimental for accumulation. By suppression of interference via the damping of traveling waves, we predict the non-Hermitian skin effect of magnetic excitation in a periodic array of magnetic nanowires that are coupled chirally via spin waves of thin magnetic films. The local excitation of a wire at one edge by weak microwaves of magnitude ∼ μT leads to a considerable spin-wave amplitude at the other edge, i.e. a remarkable functionality useful for sensitive, non-local, and non-reciprocal detection of microwaves.
TL;DR: In this article , the authors demonstrate the generation of spin-wave frequency combs based on the nonlinear interaction of propagating spin waves in a microstructured waveguide by means of time and space-resolved Brillouin light scattering spectroscopy.
Abstract: We experimentally demonstrate the generation of spin-wave frequency combs based on the nonlinear interaction of propagating spin waves in a microstructured waveguide. By means of time- and space-resolved Brillouin light scattering spectroscopy, we show that the simultaneous excitation of spin waves with different frequencies leads to a cascade of four-magnon scattering events, which ultimately results in well-defined frequency combs. Their spectral weight can be tuned by the choice of amplitude and frequency of the input signals. Furthermore, we introduce a model for stimulated four-magnon scattering, which describes the formation of spin-wave frequency combs in the frequency and time domain.
TL;DR: In this paper , a series of {ScnGdn} (n = 4, 6, 8) heterometallic rings, which are the first Sc-Ln clusters to date, with tunable magnetic interactions for spin-wave excitations.
Abstract: Data carriers using spin waves in spintronic and magnonic logic devices offer operation at low power consumption and free of Joule heating yet requiring noncollinear spin structures of small sizes. Heterometallic rings can provide such an opportunity due to the controlled spin-wave transmission within such a confined space. Here, we present a series of {ScnGdn} (n = 4, 6, 8) heterometallic rings, which are the first Sc-Ln clusters to date, with tunable magnetic interactions for spin-wave excitations. By means of time- and temperature-dependent spin dynamics simulations, we are able to predict distinct spin-wave excitations at finite temperatures for Sc4Gd4, Sc6Gd6, and Sc8Gd8. Such a new model is previously unexploited, especially due to the interplay of antiferromagnetic exchange, dipole-dipole interaction, and ring topology at low temperatures, rendering the importance of the latter to spin-wave excitations.