Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly inf...Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly influences the dispersion in the long-wave region for the spin waves of spiral wall and helical structure.For the uniform configuration,the Dzyaloshinskii-Moriya interaction determines the modification of dispersion by the damping.Furthermore,we investigate the interaction between spin waves and a moving spiral domain wall.In the presence of damping,the amplitude of spin wave can increase after running across the wall for small wave numbers.Driving by the spin waves,the wall propagates towards the spin-wave source with an increasing velocity.Unlike the case without damping,the relation between the wall velocity and the spin-wave frequency depends on the position of wall.展开更多
Ferromagnetic resonance is introduced to examine the microwave frequency response of Ni Fe/Ir Mn bilayers, patterned as antidot arrays. In the experiment, field direction dependence on mode is obtained by rotating the...Ferromagnetic resonance is introduced to examine the microwave frequency response of Ni Fe/Ir Mn bilayers, patterned as antidot arrays. In the experiment, field direction dependence on mode is obtained by rotating the applied magnetic field. We find that at a given resonance frequency, the dependence of the resonance field on the angle has a tendency of sinusoid/cosine variation in the experiment. From micromagnetic simulation it can be seen that spin waves are localized between dots from a given mode profile. This is caused by a demagnetization distribution with a larger value in the center of the two nearest dots than that of the next-nearest dots.展开更多
The voltage control of magnetism has attracted intensive attention owing to the abundant physical phenomena associated with magnetoelectric coupling. More importantly, the techniques to electrically manipulate spin dy...The voltage control of magnetism has attracted intensive attention owing to the abundant physical phenomena associated with magnetoelectric coupling. More importantly, the techniques to electrically manipulate spin dynamics, such as magnetic anisotropy and ferromagnetic resonance, are of great significance because of their potential applications in high-density memory devices, microwave signal processors, and magnetic sensors. Recently, voltage control of spin waves has also been demonstrated in several multiferroic heterostructures. This development provides new platforms for energyefficient, tunable magnonic devices. In this review, we focus on the most recent advances in voltage control of ferromagnetic resonance and spin waves in magnetoelectric materials and discuss the physical mechanisms and prospects for practical device applications.展开更多
Motivated by the discovery of a new family of 122 iron-based superconductors, we present the theoretical results on the ground state phase diagram, spin wave, and dynamic structure factor obtained from the extended J1...Motivated by the discovery of a new family of 122 iron-based superconductors, we present the theoretical results on the ground state phase diagram, spin wave, and dynamic structure factor obtained from the extended J1-J2 Heisenberg model. In the reasonable physical parameter region of K2Fe4Se5, we find that the block checkerboard antiferromagnetic order phase is stable. There are two acoustic spin wave branches and six optical spin wave branches in the block checker- board antiferromagnetic phase, which have analytic expressions at the high-symmetry points. To further compare the experimental data on neutron scattering, we investigate the saddlepoint structure of the magnetic excitation spectrum and the inelastic neutron scattering pattern based on linear spin wave theory.展开更多
We investigate the effects of long-range interactions on the spin wave spectra and the competition between magnetic phases on a frustrated square lattice with large spin S.Applying the spin wave theory and assisted wi...We investigate the effects of long-range interactions on the spin wave spectra and the competition between magnetic phases on a frustrated square lattice with large spin S.Applying the spin wave theory and assisted with symmetry analysis,we obtain analytical expressions for spin wave spectra of competing Neel and(π,0)stripe states of systems containing anyorder long-range interactions.In the specific case of long-range interactions with power-law decay,we find surprisingly that the staggered long-range interaction suppresses quantum fluctuation and enlarges the ordered moment,especially in the Neel state,and thus extends its phase boundary to the stripe state.Our findings illustrate the rich possibilities of the roles of long-range interactions,and advocate future investigations in other magnetic systems with different structures of interactions.展开更多
Investigations on domain wall(DW) and spin wave(SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the freq...Investigations on domain wall(DW) and spin wave(SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the frequencies of SW modes and the corresponding DW modes are consistent with each other if they have the same node number along the width direction. This consistency is more pronounced in wide and thin nanostrips, favoring the DW motion driven by SWs.Further analysis of the moving behavior of a DW driven by SWs is also carried out. The average DW speed can reach a larger value of ~ 140 m/s under two different SW sources. We argue that this study is very meaningful for the potential application of DW motion driven by SWs.展开更多
Nanomagnets are widely used to store information in non-volatile spintronic devices.Spin waves can transfer information with low-power consumption as their propagations are independent of charge transport.However,to d...Nanomagnets are widely used to store information in non-volatile spintronic devices.Spin waves can transfer information with low-power consumption as their propagations are independent of charge transport.However,to dynamically couple two distant nanomagnets via spin waves remains a major challenge for magnonics.Here we experimentally demonstrate coherent coupling of two distant Co nanowires by fast propagating spin waves in an yttrium iron garnet thin film with sub-50 nm wavelengths.Magnons in two nanomagnets are unidirectionally phase-locked with phase shifts controlled by magnon spin torque and spin-wave propagation.The coupled system is finally formulated by an analytical theory in terms of an effective non-Hermitian Hamiltonian.Our results are attractive for analog neuromorphic computing that requires unidirectional information transmission.展开更多
In this study,we investigated the micromagnetic dynamics of kπ-state skyrmions in a magnetic nanodot under a circular spinpolarized current and found an excited spin wave that can propagate persistently along the dir...In this study,we investigated the micromagnetic dynamics of kπ-state skyrmions in a magnetic nanodot under a circular spinpolarized current and found an excited spin wave that can propagate persistently along the direction of the radius toward the center.This dynamic process is associated with two energetically favorable states in an oscillating period of spin waves.In this case,the spin-polarized current plays a role similar to effective perpendicular magnetic anisotropy and decreases the minimum energy in the magnetic system.Our findings provide insight into understanding the dynamic behaviors of topological magnetic textures.展开更多
In a Weyl semimetal(WSM),the conduction and valence bands cross each other near the Fermi energy,and the crossing points,called Weyl points,exhibit a monopole-like distribution of the Berry curvature.The Berry curvatu...In a Weyl semimetal(WSM),the conduction and valence bands cross each other near the Fermi energy,and the crossing points,called Weyl points,exhibit a monopole-like distribution of the Berry curvature.The Berry curvature is a fictitious magnetic field in the momentum-space and induces the anomalous velocity to the real-space electron motion.Therefore,Weyl monopoles play essential roles in the charge transport,for example,the anomalous Hall effect(AHE).The anomalous Hall conductivity(AHC)is nearly proportional to the distance between the Weyl point pairs with opposite chirality.The magnetic order and spin structure sensitively modify Weyl point positions and energies.展开更多
In this Letter,we report an Airy-like beam of magnetostatic surface spin wave(Ai BMSSW)supported on the ferromagnetic film,which is transferred from the optical field.The propagation properties of Ai BMSSW were verifi...In this Letter,we report an Airy-like beam of magnetostatic surface spin wave(Ai BMSSW)supported on the ferromagnetic film,which is transferred from the optical field.The propagation properties of Ai BMSSW were verified with micromagnetic simulation.From simulation results,the typical parabolic trajectory of the Airy-type beam was observed with an exciting source encoding 3/2 phase pattern.The simulation results coincide well with design parameters.Furthermore,simulated results showed that the trajectories of the Ai BMSSW could be tuned readily with varied external magnetic fields.This work can extend the application scenario of spin waves.展开更多
We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)as...We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)asymmetric skew scattering,depending on the polarity of vortex core,(ii)back scattering(reflection),depending on the vortex core stiffness,(iii)side deflection scattering,depending on structural symmetry of the vortex circulation,and(iv)geometrical scattering,depending on waveguide structure.The first and second scattering behaviors are attributed to nonlinear topological magnon spin Hall effect related to magnon spin-transfer torque effect,which has value for magnonic exploration and application.展开更多
Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, e...Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, especially the frequency stability, are seriously affected by the relaxation of the interface magnetic moments. In this study, the effect of out-of-plane magnetization depinning on the resonance frequency shift(△ fr) was investigated for 3-μm YIG films grown on Gd3Ga5O12(GGG)(111) substrates by liquid-phase epitaxy. It is revealed that the ferromagnetic resonance(FMR) and spin wave propagation exhibit a very slow relaxation with relaxation time τ even longer than one hour under an out-of-plane external magnetic bias field. The △ fr span of 15.15–24.70 MHz is observed in out-of-plane FMR and forward volume spin waves. Moreover, the △ fr and τ depend on the magnetic field. The △ fr can be attributed to that the magnetic moments break away from the pinning layer at the YIG/GGG interface. The thickness of the pinning layer is estimated to be about9.48 nm to 15.46 nm according to the frequency shifting. These results indicate that △ fr caused by the pinning layer should be addressed in the design of microwave and spin wave devices, especially in the transverse magnetic components.展开更多
We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. ...We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.展开更多
An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the ...An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.展开更多
We investigated the angle-dependent spin wave spectra of permalloy ring arrays with the fixed outer diameter and various inner diameters by ferromagnetic resonance spectroscopy and micromagnetic simulation.When the fi...We investigated the angle-dependent spin wave spectra of permalloy ring arrays with the fixed outer diameter and various inner diameters by ferromagnetic resonance spectroscopy and micromagnetic simulation.When the field is obliquely applied to the ring,local resonance mode can be observed in different parts of the rings.And the resonance mode will change to perpendicular spin standing waves if the magnetic field is applied along the perpendicular direction.The simulation results demonstrated this evolution and implied more resonance modes that maybe exist.And the mathematical fitting results based on the Kittel equation further proved the existence of local resonance mode.展开更多
This paper proposes a symmetry ensemble model for the magnetic dynamics caused by spin transfer torque in nanoscale pseudo-spin-valves, in which individual spin moments in the free layer are considered as subsystems t...This paper proposes a symmetry ensemble model for the magnetic dynamics caused by spin transfer torque in nanoscale pseudo-spin-valves, in which individual spin moments in the free layer are considered as subsystems to form a spinor ensemble. The magnetization dynamics equation of the ensemble was developed. By analytically investigating the equation, many magnetization dynamics properties excited by polarized current reported in experiments, such as double spin wave modes and the abrupt frequency jump, can be successfully explained. It is pointed out that an external field is not necessary for spin wave emitting (SWE) and a novel perpendicular configuration structure can provide much higher SWE efficiency in zero magnetic field.展开更多
The magnetization curves at 1.5 K and thermomagnetic curves for amorphous Fe_(90-x)Si_xZr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique have been measured with an extracting sample magnetometer.It...The magnetization curves at 1.5 K and thermomagnetic curves for amorphous Fe_(90-x)Si_xZr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique have been measured with an extracting sample magnetometer.It is obtained that the average magnetic moment,,per magnetic atom and Curie temperature,T_c,in the amorphous FeSiZr alloys increase with increasing Si content.The and T_c are found to be quite small,compared with amorphous FeSiB alloys.This unusual behavior is suggested to be due to the presence of the Fe—Fe antiferromagnetic interactions.The temperature dependence of magnetization at lower temperature is in accordance with Bloch's T^(3/2) law.Calculation shows that the spin wave stiffness constant,D,increases with increasing Si content from 0.37 meV·nm^2 for x=0 to 0.538 meV·nm^2 for x=10.The values of<r^2>indicate that the range of the exchange interaction is roughly the mean atomic distance of nearest neighbours.展开更多
The synchronization of the spin Hall nano-oscillator(SHNO)device driven by the pure spin current has been investigated with micromagnetic simulations.It was found that the power spectra of nanowire-based SHNO devices ...The synchronization of the spin Hall nano-oscillator(SHNO)device driven by the pure spin current has been investigated with micromagnetic simulations.It was found that the power spectra of nanowire-based SHNO devices can be synchronized by varying the current flowing in the heavy metal(HM)layer.The synchronized signals have relatively high power and narrow linewidth,favoring the potential applications.We also found that the synchronized spectra are strongly dependent on both the number and length of nanowires.Moreover,a periodic modulation of power spectra can be obtained by introducing interfacial Dzyaloshinskii–Moriya interaction(iDMI).Our findings could enrich the current understanding of spin dynamics driven by the pure spin current.Further,it could help to design novel spintronic devices.展开更多
Elastic neutron diffraction measurements were performed on single crystals to study the ground state below the mysterious exotic transition temperature 0.86 K. An antiferromagnetic order with a tiny moment of 0.027 μ...Elastic neutron diffraction measurements were performed on single crystals to study the ground state below the mysterious exotic transition temperature 0.86 K. An antiferromagnetic order with a tiny moment of 0.027 μB per formula is formed as the ground state for CeOs4Sb12 below the transition point. Our neutron data gives the evidence of spin density wave state for CeOs4Sb12 in this work.展开更多
In quasi-one-dimensional(q1D) quantum antiferromagnets, the complicated interplay of intrachain and interchain exchange couplings may give rise to rich phenomena. Motivated by recent progress on field-induced phase tr...In quasi-one-dimensional(q1D) quantum antiferromagnets, the complicated interplay of intrachain and interchain exchange couplings may give rise to rich phenomena. Motivated by recent progress on field-induced phase transitions in the q1D antiferromagnetic(AFM) compound YbAlO3, we study the phase diagram of spin-1/2 Heisenberg chains with Ising anisotropic interchain couplings under a longitudinal magnetic field via large-scale quantum Monte Carlo simulations,and investigate the role of the spin anisotropy of the interchain coupling on the ground state of the system. We find that the Ising anisotropy of the interchain coupling can significantly enhance the longitudinal spin correlations and drive the system to an incommensurate AFM phase at intermediate magnetic fields, which is understood as a longitudinal spin density wave(LSDW). With increasing field, the ground state changes to a canted AFM order with transverse spin correlations. We further provide a global phase diagram showing how the competition between the LSDW and the canted AFM states is tuned by the Ising anisotropy of the interchain coupling.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774001 and 51972103)the Natural Science Foundation of Hebei Province of China(Grant No.F2019202141)the Fund of the State Key Laboratory of Quantum Optics and Quantum Optics Devices,Shanxi University,China(Grant No.KF201906).
文摘Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly influences the dispersion in the long-wave region for the spin waves of spiral wall and helical structure.For the uniform configuration,the Dzyaloshinskii-Moriya interaction determines the modification of dispersion by the damping.Furthermore,we investigate the interaction between spin waves and a moving spiral domain wall.In the presence of damping,the amplitude of spin wave can increase after running across the wall for small wave numbers.Driving by the spin waves,the wall propagates towards the spin-wave source with an increasing velocity.Unlike the case without damping,the relation between the wall velocity and the spin-wave frequency depends on the position of wall.
基金Project supported by the National Natural Science Foundation of China(Grant No.11304407)the Scientific Research Foundation for Returned Scholars,Ministry of Education of China(Grant No.47)
文摘Ferromagnetic resonance is introduced to examine the microwave frequency response of Ni Fe/Ir Mn bilayers, patterned as antidot arrays. In the experiment, field direction dependence on mode is obtained by rotating the applied magnetic field. We find that at a given resonance frequency, the dependence of the resonance field on the angle has a tendency of sinusoid/cosine variation in the experiment. From micromagnetic simulation it can be seen that spin waves are localized between dots from a given mode profile. This is caused by a demagnetization distribution with a larger value in the center of the two nearest dots than that of the next-nearest dots.
基金Project supported by the National Natural Science Foundation of China(Grant No.51602244)the National 111 Project of China(Grant No.B14040)the Fundamental Research Funds for the Central Universities,China(Grant No.xjj2018207)
文摘The voltage control of magnetism has attracted intensive attention owing to the abundant physical phenomena associated with magnetoelectric coupling. More importantly, the techniques to electrically manipulate spin dynamics, such as magnetic anisotropy and ferromagnetic resonance, are of great significance because of their potential applications in high-density memory devices, microwave signal processors, and magnetic sensors. Recently, voltage control of spin waves has also been demonstrated in several multiferroic heterostructures. This development provides new platforms for energyefficient, tunable magnonic devices. In this review, we focus on the most recent advances in voltage control of ferromagnetic resonance and spin waves in magnetoelectric materials and discuss the physical mechanisms and prospects for practical device applications.
基金supported by the Science Foundation for Post-Doctorate Research from the Ministry of Science and Technology of China (Grant No.20100470589)the National Basic Research Program of China (Grant No.2007CB925000)the National Natural Science Foundation of China (Grant No.51071032)
文摘Motivated by the discovery of a new family of 122 iron-based superconductors, we present the theoretical results on the ground state phase diagram, spin wave, and dynamic structure factor obtained from the extended J1-J2 Heisenberg model. In the reasonable physical parameter region of K2Fe4Se5, we find that the block checkerboard antiferromagnetic order phase is stable. There are two acoustic spin wave branches and six optical spin wave branches in the block checker- board antiferromagnetic phase, which have analytic expressions at the high-symmetry points. To further compare the experimental data on neutron scattering, we investigate the saddlepoint structure of the magnetic excitation spectrum and the inelastic neutron scattering pattern based on linear spin wave theory.
基金supported by NKRDPC2018YFA0306001,NKRDPC-2022YFA1402802,NSFC-92165204,NSFC-11974432,GBABRF-2019A1515011337,Shenzhen International Quantum Academy(Grant No.SIQA202102)Leading Talent Program of Guangdong Special Projects(No.201626003).
文摘We investigate the effects of long-range interactions on the spin wave spectra and the competition between magnetic phases on a frustrated square lattice with large spin S.Applying the spin wave theory and assisted with symmetry analysis,we obtain analytical expressions for spin wave spectra of competing Neel and(π,0)stripe states of systems containing anyorder long-range interactions.In the specific case of long-range interactions with power-law decay,we find surprisingly that the staggered long-range interaction suppresses quantum fluctuation and enlarges the ordered moment,especially in the Neel state,and thus extends its phase boundary to the stripe state.Our findings illustrate the rich possibilities of the roles of long-range interactions,and advocate future investigations in other magnetic systems with different structures of interactions.
基金Project supported by the Fundamental Research Funds for the Central Universities (Grant No. 20720210030)the National Natural Science Foundation of China (Grant No. 11204255)。
文摘Investigations on domain wall(DW) and spin wave(SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the frequencies of SW modes and the corresponding DW modes are consistent with each other if they have the same node number along the width direction. This consistency is more pronounced in wide and thin nanostrips, favoring the DW motion driven by SWs.Further analysis of the moving behavior of a DW driven by SWs is also carried out. The average DW speed can reach a larger value of ~ 140 m/s under two different SW sources. We argue that this study is very meaningful for the potential application of DW motion driven by SWs.
基金We wish to acknowledge the support by the National Key Research and Development Program of China(Nos.2016YFA0300802 and 2017YFA0206200)the National Natural Science Foundation of China(NSFC)(Nos.11674020,12074026 and U1801661)+6 种基金the 111 talent program B16001G.B.was supported by the Netherlands Organization for Scientific Research(NWO)and Japan Society for the Promotion of Science Kakenhi Grants-in-Aid for Scientific Research(No.19H006450)T.Y.was funded through the Emmy Noether Program of Deutsche Forschungsgemeinschaft(SE 2558/2-1)K.X.thanks the National Key Research and Development Program of China(Nos.2017YFA0303304 and 2018YFB0407601)the National Natural Science Foundation of China(Nos.61774017 and 11734004)K.S.was supported by the Fundamental Research Funds for the Central Universities(No.2018EYT02)M.Z.W.were supported by the US National Science Foundation(No.EFMA-1641989).
文摘Nanomagnets are widely used to store information in non-volatile spintronic devices.Spin waves can transfer information with low-power consumption as their propagations are independent of charge transport.However,to dynamically couple two distant nanomagnets via spin waves remains a major challenge for magnonics.Here we experimentally demonstrate coherent coupling of two distant Co nanowires by fast propagating spin waves in an yttrium iron garnet thin film with sub-50 nm wavelengths.Magnons in two nanomagnets are unidirectionally phase-locked with phase shifts controlled by magnon spin torque and spin-wave propagation.The coupled system is finally formulated by an analytical theory in terms of an effective non-Hermitian Hamiltonian.Our results are attractive for analog neuromorphic computing that requires unidirectional information transmission.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LR18E010001)the National Natural Science Foundation of China(Grant Nos.U1704253,and 51471045)the Fundamental Research Funds for the Central Universities(Grant No.N160208001)。
文摘In this study,we investigated the micromagnetic dynamics of kπ-state skyrmions in a magnetic nanodot under a circular spinpolarized current and found an excited spin wave that can propagate persistently along the direction of the radius toward the center.This dynamic process is associated with two energetically favorable states in an oscillating period of spin waves.In this case,the spin-polarized current plays a role similar to effective perpendicular magnetic anisotropy and decreases the minimum energy in the magnetic system.Our findings provide insight into understanding the dynamic behaviors of topological magnetic textures.
文摘In a Weyl semimetal(WSM),the conduction and valence bands cross each other near the Fermi energy,and the crossing points,called Weyl points,exhibit a monopole-like distribution of the Berry curvature.The Berry curvature is a fictitious magnetic field in the momentum-space and induces the anomalous velocity to the real-space electron motion.Therefore,Weyl monopoles play essential roles in the charge transport,for example,the anomalous Hall effect(AHE).The anomalous Hall conductivity(AHC)is nearly proportional to the distance between the Weyl point pairs with opposite chirality.The magnetic order and spin structure sensitively modify Weyl point positions and energies.
基金supported in part by the National Natural Science Foundation of China(Nos.61975148 and 11535008)。
文摘In this Letter,we report an Airy-like beam of magnetostatic surface spin wave(Ai BMSSW)supported on the ferromagnetic film,which is transferred from the optical field.The propagation properties of Ai BMSSW were verified with micromagnetic simulation.From simulation results,the typical parabolic trajectory of the Airy-type beam was observed with an exciting source encoding 3/2 phase pattern.The simulation results coincide well with design parameters.Furthermore,simulated results showed that the trajectories of the Ai BMSSW could be tuned readily with varied external magnetic fields.This work can extend the application scenario of spin waves.
基金Project supported by the Basic Science Research Program of the National Research Foundation of Korea(Grant No.2021R1F1A1050539)the Yanbian University Research Project(Grant No.482022104)the Yichang Natural Science Research Project(Grant No.A22-3-010)。
文摘We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)asymmetric skew scattering,depending on the polarity of vortex core,(ii)back scattering(reflection),depending on the vortex core stiffness,(iii)side deflection scattering,depending on structural symmetry of the vortex circulation,and(iv)geometrical scattering,depending on waveguide structure.The first and second scattering behaviors are attributed to nonlinear topological magnon spin Hall effect related to magnon spin-transfer torque effect,which has value for magnonic exploration and application.
基金National Natural Science Foundation of China(Grant Nos.11674187 and 51871127)Technology on Electronic Test&Measurement Laboratory(Grant No.6142001180103).
文摘Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, especially the frequency stability, are seriously affected by the relaxation of the interface magnetic moments. In this study, the effect of out-of-plane magnetization depinning on the resonance frequency shift(△ fr) was investigated for 3-μm YIG films grown on Gd3Ga5O12(GGG)(111) substrates by liquid-phase epitaxy. It is revealed that the ferromagnetic resonance(FMR) and spin wave propagation exhibit a very slow relaxation with relaxation time τ even longer than one hour under an out-of-plane external magnetic bias field. The △ fr span of 15.15–24.70 MHz is observed in out-of-plane FMR and forward volume spin waves. Moreover, the △ fr and τ depend on the magnetic field. The △ fr can be attributed to that the magnetic moments break away from the pinning layer at the YIG/GGG interface. The thickness of the pinning layer is estimated to be about9.48 nm to 15.46 nm according to the frequency shifting. These results indicate that △ fr caused by the pinning layer should be addressed in the design of microwave and spin wave devices, especially in the transverse magnetic components.
文摘We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074189,11704191,11774160,and 61427812)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20192006 and BK20211144)the Postdoctoral Research Funding Program of Jiangsu Province,China(Grant No.2021K503C)。
文摘An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074158,12174166,and 12104197)。
文摘We investigated the angle-dependent spin wave spectra of permalloy ring arrays with the fixed outer diameter and various inner diameters by ferromagnetic resonance spectroscopy and micromagnetic simulation.When the field is obliquely applied to the ring,local resonance mode can be observed in different parts of the rings.And the resonance mode will change to perpendicular spin standing waves if the magnetic field is applied along the perpendicular direction.The simulation results demonstrated this evolution and implied more resonance modes that maybe exist.And the mathematical fitting results based on the Kittel equation further proved the existence of local resonance mode.
基金supported by Major State Basic Research Development Program of China(Grant No 2006CB921106)the National Natural Science Foundation of China(Grant No 60606021)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No 20060003067)
文摘This paper proposes a symmetry ensemble model for the magnetic dynamics caused by spin transfer torque in nanoscale pseudo-spin-valves, in which individual spin moments in the free layer are considered as subsystems to form a spinor ensemble. The magnetization dynamics equation of the ensemble was developed. By analytically investigating the equation, many magnetization dynamics properties excited by polarized current reported in experiments, such as double spin wave modes and the abrupt frequency jump, can be successfully explained. It is pointed out that an external field is not necessary for spin wave emitting (SWE) and a novel perpendicular configuration structure can provide much higher SWE efficiency in zero magnetic field.
文摘The magnetization curves at 1.5 K and thermomagnetic curves for amorphous Fe_(90-x)Si_xZr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique have been measured with an extracting sample magnetometer.It is obtained that the average magnetic moment,,per magnetic atom and Curie temperature,T_c,in the amorphous FeSiZr alloys increase with increasing Si content.The and T_c are found to be quite small,compared with amorphous FeSiB alloys.This unusual behavior is suggested to be due to the presence of the Fe—Fe antiferromagnetic interactions.The temperature dependence of magnetization at lower temperature is in accordance with Bloch's T^(3/2) law.Calculation shows that the spin wave stiffness constant,D,increases with increasing Si content from 0.37 meV·nm^2 for x=0 to 0.538 meV·nm^2 for x=10.The values of<r^2>indicate that the range of the exchange interaction is roughly the mean atomic distance of nearest neighbours.
基金the National Basic Research Program of Natural Science Foundation of China(Grant Nos.12074220,and 11627805)the 111 Project(Grant No.B13029)。
文摘The synchronization of the spin Hall nano-oscillator(SHNO)device driven by the pure spin current has been investigated with micromagnetic simulations.It was found that the power spectra of nanowire-based SHNO devices can be synchronized by varying the current flowing in the heavy metal(HM)layer.The synchronized signals have relatively high power and narrow linewidth,favoring the potential applications.We also found that the synchronized spectra are strongly dependent on both the number and length of nanowires.Moreover,a periodic modulation of power spectra can be obtained by introducing interfacial Dzyaloshinskii–Moriya interaction(iDMI).Our findings could enrich the current understanding of spin dynamics driven by the pure spin current.Further,it could help to design novel spintronic devices.
文摘Elastic neutron diffraction measurements were performed on single crystals to study the ground state below the mysterious exotic transition temperature 0.86 K. An antiferromagnetic order with a tiny moment of 0.027 μB per formula is formed as the ground state for CeOs4Sb12 below the transition point. Our neutron data gives the evidence of spin density wave state for CeOs4Sb12 in this work.
基金Project supported by the National Natural Science Foundation of China(Grant No.11674392)the Ministry of Science and Technology of China,National Program on Key Research Project(Grant No.2016YFA0300504)the Research Funds of Remnin University of China(Grant No.18XNLG24).
文摘In quasi-one-dimensional(q1D) quantum antiferromagnets, the complicated interplay of intrachain and interchain exchange couplings may give rise to rich phenomena. Motivated by recent progress on field-induced phase transitions in the q1D antiferromagnetic(AFM) compound YbAlO3, we study the phase diagram of spin-1/2 Heisenberg chains with Ising anisotropic interchain couplings under a longitudinal magnetic field via large-scale quantum Monte Carlo simulations,and investigate the role of the spin anisotropy of the interchain coupling on the ground state of the system. We find that the Ising anisotropy of the interchain coupling can significantly enhance the longitudinal spin correlations and drive the system to an incommensurate AFM phase at intermediate magnetic fields, which is understood as a longitudinal spin density wave(LSDW). With increasing field, the ground state changes to a canted AFM order with transverse spin correlations. We further provide a global phase diagram showing how the competition between the LSDW and the canted AFM states is tuned by the Ising anisotropy of the interchain coupling.