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
Many studies of magnon–photon coupling are performed in the frequency domain for microwave photons.In this work,we present analytical results of eigenfrequency,eigenstates,and temporal dynamics for the coupling betwe...Many studies of magnon–photon coupling are performed in the frequency domain for microwave photons.In this work,we present analytical results of eigenfrequency,eigenstates,and temporal dynamics for the coupling between ferromagnetic magnon and visible photon.In contrast to microwave photons,optical photons can be coupled with magnon in a dispersive interaction which produces both level repulsion and attraction by varying the magnon–photon frequency detuning.At resonance,the hybridized states are of linear polarization and circular polarization for level repulsion and level attraction respectively.As the detuning increases,the polarizations of level repulsion remain linear but those of level attraction vary from elliptical to linear polarizations.The temporal dynamics of level repulsion presents the beat-like behavior.The level attraction presents monotonous decay in the weak coupling regime but gives rise to instability in the strong coupling regime due to the magnon amplification.As the detuning is large,both magnon and photon amplitudes present a synchronizing oscillation.Our results are important for exploring the temporal evolution of magnon–photon coupling in the range of optical frequency and designing magnon-based timing devices.展开更多
Using the plane-wave expansion method, the spin-wave band structures of two-dimensional magnonic crystals consisting of square arrays of different shape scatterers are calculated numerically, and the effects of rotati...Using the plane-wave expansion method, the spin-wave band structures of two-dimensional magnonic crystals consisting of square arrays of different shape scatterers are calculated numerically, and the effects of rotating rectangle and hexagon scaterers on the gaps are studied, respectively. The results show that the gaps can be substantially opened and tuned by rotating the scatterers. This approach should be helpful in designing magnonic crystals with desired gaps.展开更多
In this review,the recent developments in microelectronics,spintronics,and magnonics have been summarized and compared.Firstly,the history of the spintronics has been briefly reviewed.Moreover,the recent development o...In this review,the recent developments in microelectronics,spintronics,and magnonics have been summarized and compared.Firstly,the history of the spintronics has been briefly reviewed.Moreover,the recent development of magnonics such as magnon-mediated current drag effect(MCDE),magnon valve effect(MVE),magnon junction effect(MJE),magnon blocking effect(MBE),magnon-mediated nonlocal spin Hall magnetoresistance(MNSMR),magnon-transfer torque(MTT)effect,and magnon resonant tunneling(MRT)effect,magnon skin effect(MSE),etc.,existing in magnon junctions or magnon heterojunctions,have been summarized and their potential applications in memory and logic devices,etc.,are prospected,from which we can see a promising future for spintronics and magnonics beyond micro-electronics.展开更多
When there is a certain amount of field inhomogeneity,the biased ferrimagnetic crystal can exhibit the higher-order magnetostatic(HMS)mode in addition to the uniform-precession Kittel mode.In cavity magnonics,we show ...When there is a certain amount of field inhomogeneity,the biased ferrimagnetic crystal can exhibit the higher-order magnetostatic(HMS)mode in addition to the uniform-precession Kittel mode.In cavity magnonics,we show the nonlinearity and heating-induced frequency shifts of the Kittel mode and HMS mode in a yttrium-iron-garnet(YIG)sphere.When the Kittel mode is driven to generate a certain number of excitations,the temperature of the whole YIG sample rises and the HMS mode can display an induced frequency shift,and vice versa.This cross effect provides a new method to study the magnetization dynamics and paves a way for novel cavity magnonic devices by including the heating effect as an operational degree of freedom.展开更多
A magnonic counterpart to optical frequency combs is vital for high-precision magnonic frequency metrology and spectroscopy.Here,we present an efficient mechanism for the generation of robust magnonic frequency combs ...A magnonic counterpart to optical frequency combs is vital for high-precision magnonic frequency metrology and spectroscopy.Here,we present an efficient mechanism for the generation of robust magnonic frequency combs in a yttrium iron garnet(YIG)sphere via magnetostrictive effects.We show that magnonic and vibrational dynamics in the ferrimagnetic sphere can be substantively modified in the presence of magnetostrictive effects,which results in degenerate and non-degenerate magnonic four-wave mixing and frequency conversion.Particularly,resonantly enhanced magnetostrictive effects can induce phonon laser action above a threshold,which leads to significant magnonic nonlinearity and enables a potentially practical scheme for the generation of robust magnonic frequency combs.Numerical calculations of both magnonic and phononic dynamics show excellent agreement with this theory.These results deepen our understanding of magnetostrictive interaction,open a novel and efficient pathway to realize magnonic frequency conversion and mixing in a magnonic device,and provide a sensitive tool for precision measurement.展开更多
Recently,the photon–magnon coherent interaction based on the collective spins excitation in ferromagnetic materials has been achieved experimentally.Under the prospect,the magnons are proposed to store and process qu...Recently,the photon–magnon coherent interaction based on the collective spins excitation in ferromagnetic materials has been achieved experimentally.Under the prospect,the magnons are proposed to store and process quantum information.Meanwhile,cavity-optomagnonics which describes the interaction between photons and magnons has been developing rapidly as an interesting topic of the cavity quantum electrodynamics.Here in this short review,we mainly introduce the recent theoretical and experimental progress in the field of optomagnetic coupling and optical manipulation based on cavity-optomagnonics.According to the frequency range of the electromagnetic field,cavity optomagnonics can be divided into microwave cavity optomagnonics and optical cavity optomagnonics,due to the different dynamics of the photon–magnon interaction.As the interaction between the electromagnetic field and the magnetic materials is enhanced in the cavity-optomagnonic system,it provides great significance to explore the nonlinear characteristics and quantum properties for different magnetic systems.More importantly,the electromagnetic response of optomagnonics covers the frequency range from gigahertz to terahertz which provides a broad frequency platform for the multi-mode controlling in quantum systems.展开更多
We develop a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet(YIG) sphere strongly coupled to cavity photons, and use it to study the bistability in ...We develop a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet(YIG) sphere strongly coupled to cavity photons, and use it to study the bistability in this hybrid system. To have a complete picture of the bistability phenomenon, we analyze two different cases in driving the cavity magnonics system, i.e.,directly pumping the YIG sphere and the cavity, respectively. In both cases, the magnon frequency shifts due to the Kerr effect exhibit a similar bistable behavior but the corresponding critical powers are different. Moreover, we show how the bistability of the system can be demonstrated using the transmission spectrum of the cavity. Our results are valid in a wide parameter regime and generalize the theory of bistability in a cavity magnonics system.展开更多
Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical...Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method.We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single-and two-magnon excitations,respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.展开更多
This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya interaction.Using a first-order Green function method,we analyze the i...This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya interaction.Using a first-order Green function method,we analyze the influence of magnon-magnon interaction on the magnon band topology.We find that Chern numbers of two renormalized magnon bands are different above and below the critical temperature,which means that the magnon band gap-closing phenomenon is an indicator for one topological phase transition of the checkerboard ferromagnet.Our results show that the checkerboard ferromagnet possesses two topological phases,and its topological phase can be controlled either via the temperature or the applied magnetic field due to magnon-magnon interactions.Interestingly,it is found that the topological phase transition can occur twice with the increase in the temperature,which is different from the results of the honeycomb ferromagnet.展开更多
The field of magnonics,which aims at using spin waves as carriers in data-processing devices,has attracted increasing interest in recent years.We present and study micromagnetically a nonlinear nanoscale magnonic ring...The field of magnonics,which aims at using spin waves as carriers in data-processing devices,has attracted increasing interest in recent years.We present and study micromagnetically a nonlinear nanoscale magnonic ring resonator device for enabling implementations of magnonic logic gates and neuromorphic magnonic circuits.In the linear regime,this device efficiently suppresses spin-wave transmission using the phenomenon of critical resonant coupling,thus exhibiting the behavior of a notch filter.By increasing the spin-wave input power,the resonance frequency is shifted,leading to transmission curves,depending on the frequency,reminiscent of the activation functions of neurons,or showing the characteristics of a power limiter.An analytical theory is developed to describe the transmission curve of magnonic ring resonators in the linear and nonlinear regimes,and is validated by a comprehensive micromagnetic study.The proposed magnonic ring resonator provides a multi-functional nonlinear building block for unconventional magnonic circuits.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
Liquid phase epitaxy (LPE) is a mature technology. Early experiments on single magnetic crystal films fabricated by LPE were focused mainly on thick films for microwave and magneto-optical devices. The LPE is an exc...Liquid phase epitaxy (LPE) is a mature technology. Early experiments on single magnetic crystal films fabricated by LPE were focused mainly on thick films for microwave and magneto-optical devices. The LPE is an excellent way to make a thick film, low damping magnetic garnet film and high-quality magneto-optical material. Today, the principal challenge in the applied material is to create sub-micrometer devices by using modern photolithography technique. Until now the magnetic garnet films fabricated by LPE still show the best quality even on a nanoscale (about 100 nm), which was considered to be impossible for LPE method.展开更多
Ultrathin van der Waals(vdW)magnets provide a possibility to access magnetic ordering in the two-dimensional(2D)limit,which are expected to be applied in the spintronic devices.Raman spectroscopy is a powerful charact...Ultrathin van der Waals(vdW)magnets provide a possibility to access magnetic ordering in the two-dimensional(2D)limit,which are expected to be applied in the spintronic devices.Raman spectroscopy is a powerful characterization method to investigate the spin-related properties in 2D vdW magnets,including magnon and spin–lattice interaction,which are hardly accessible by other optical methods.In this paper,the recent progress of various magnetic properties in 2D vdW magnets studied by Raman spectroscopy is reviewed,including the magnetic transition,spin-wave,spin–lattice interaction,symmetry tuning induced by spin ordering,and nonreciprocal magneto-phonon Raman scattering.展开更多
Magnon-magnon coupling in synthetic antiferromagnets advances it as hybrid magnonic systems to explore the quantum information technologies.To induce magnon-magnon coupling,the parity symmetry between two magnetizatio...Magnon-magnon coupling in synthetic antiferromagnets advances it as hybrid magnonic systems to explore the quantum information technologies.To induce magnon-magnon coupling,the parity symmetry between two magnetization needs to be broken.Here we experimentally demonstrate a convenient method to break the parity symmetry by the asymmetric structure.We successfully introduce a magnon-magnon coupling in Ir-based synthetic antiferromagnets CoFeB(10 nm)/Ir(t_(Ir)=0.6 nm,1.2 nm)/CoFeB(13 nm).Remarkably,we find that the weakly uniaxial anisotropy field(-20 Oe)makes the magnon-magnon coupling anisotropic.The coupling strength presented by a characteristic anticrossing gap varies in the range between 0.54 GHz and 0.90 GHz for t_(Ir)=0.6 nm,and between 0.09 GHz and 1.4 GHz for t_(Ir)=1.2 nm.Our results demonstrate a feasible way to induce magnon-magnon coupling by an asymmetric structure and tune the coupling strength by varying the direction of in-plane magnetic field.The magnon-magnon coupling in this highly tunable material system could open exciting perspectives for exploring quantum-mechanical coupling phenomena.展开更多
An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic par...An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2/|TJ|2 ) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe21(25 nm)/lr22Mn78(12 nm)/Co75Fe25(4 nm)/AI(0.8 nm)-oxide/Co75Fe25(4 nm)/Ni79Fe21(20 nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.展开更多
The topological magnon insulator on a honeycomb lattice with Dzyaloshinskii–Moriya interaction(DMI) is studied under the application of a circularly polarized light.At the high-frequency regime, the effective tight-b...The topological magnon insulator on a honeycomb lattice with Dzyaloshinskii–Moriya interaction(DMI) is studied under the application of a circularly polarized light.At the high-frequency regime, the effective tight-binding model is obtained based on Brillouin–Wigner theory.Then, we study the corresponding Berry curvature and Chern number.In the Dirac model, the interplay between a light-induced handedness-dependent effective DMI and intrinsic DMI is discussed.展开更多
Skyrmions are very promising for applications in spintronics and magnetic memory.It is desired to manipulate and operate a single skyrmion.Here we report on the thermal effect on the motion of current-driven magnetic ...Skyrmions are very promising for applications in spintronics and magnetic memory.It is desired to manipulate and operate a single skyrmion.Here we report on the thermal effect on the motion of current-driven magnetic Skyrmions in magnetic metal.The results show that the magnon current induced by the thermal gradient acts on Skyrmions via magnonic spin-transfer torque,an effect of the transverse and longitudinal Skyrmions drift velocities,thus leading to the effective manipulation of the Hall angle through the ratio of thermal gradient to electric current density,which can be used as a Skyrmion valve.展开更多
The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach (IRA). The results show that interface coupling bet...The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach (IRA). The results show that interface coupling between two sublayers would not change the excitation energy of odd bulk modes, but change excitation energy of even bulk modes. We call this peculiar phenomenon the phenomenon of even bulk mode variance (PEBMV). There are two kinds of mechanisms which cause PEBMV: phase reversal and phase translation of the magnon at the interface, corresponding, respectively, to the antiferromagnetic and ferromagnetic interface coupling cases. PEBMV embodies the selective effect of the interface on different bulk magnons.展开更多
Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency ...Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.展开更多
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.NSFC61974067 and 62374087)。
文摘Many studies of magnon–photon coupling are performed in the frequency domain for microwave photons.In this work,we present analytical results of eigenfrequency,eigenstates,and temporal dynamics for the coupling between ferromagnetic magnon and visible photon.In contrast to microwave photons,optical photons can be coupled with magnon in a dispersive interaction which produces both level repulsion and attraction by varying the magnon–photon frequency detuning.At resonance,the hybridized states are of linear polarization and circular polarization for level repulsion and level attraction respectively.As the detuning increases,the polarizations of level repulsion remain linear but those of level attraction vary from elliptical to linear polarizations.The temporal dynamics of level repulsion presents the beat-like behavior.The level attraction presents monotonous decay in the weak coupling regime but gives rise to instability in the strong coupling regime due to the magnon amplification.As the detuning is large,both magnon and photon amplitudes present a synchronizing oscillation.Our results are important for exploring the temporal evolution of magnon–photon coupling in the range of optical frequency and designing magnon-based timing devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.11264028 and 11072104)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Grant No.2012MS0114)the School Scientific Research Funds of Inner Mongolia Normal University of China(Grant Nos.2013YJRC007 and 2013ZRYB19)
文摘Using the plane-wave expansion method, the spin-wave band structures of two-dimensional magnonic crystals consisting of square arrays of different shape scatterers are calculated numerically, and the effects of rotating rectangle and hexagon scaterers on the gaps are studied, respectively. The results show that the gaps can be substantially opened and tuned by rotating the scatterers. This approach should be helpful in designing magnonic crystals with desired gaps.
基金Project supported by the National Key Research and Development Program of China(Grants No.2017YFA0206200)the National Natural Science Foundation of China(Grant Nos.51831012 and 12134107)the Beijing Natural Science Foundation(Grant No.Z201100004220006)。
文摘In this review,the recent developments in microelectronics,spintronics,and magnonics have been summarized and compared.Firstly,the history of the spintronics has been briefly reviewed.Moreover,the recent development of magnonics such as magnon-mediated current drag effect(MCDE),magnon valve effect(MVE),magnon junction effect(MJE),magnon blocking effect(MBE),magnon-mediated nonlocal spin Hall magnetoresistance(MNSMR),magnon-transfer torque(MTT)effect,and magnon resonant tunneling(MRT)effect,magnon skin effect(MSE),etc.,existing in magnon junctions or magnon heterojunctions,have been summarized and their potential applications in memory and logic devices,etc.,are prospected,from which we can see a promising future for spintronics and magnonics beyond micro-electronics.
基金Project supported by the National Natural Science Foundation of China(Grants Nos.11934010,U1801661,and 12174329)the Zhejiang Province Program for Science and Technology(Grant No.2020C01019)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2021FZZX001-02)the China Postdoctoral Science Foundation(Grant No.2019M660137)
文摘When there is a certain amount of field inhomogeneity,the biased ferrimagnetic crystal can exhibit the higher-order magnetostatic(HMS)mode in addition to the uniform-precession Kittel mode.In cavity magnonics,we show the nonlinearity and heating-induced frequency shifts of the Kittel mode and HMS mode in a yttrium-iron-garnet(YIG)sphere.When the Kittel mode is driven to generate a certain number of excitations,the temperature of the whole YIG sample rises and the HMS mode can display an induced frequency shift,and vice versa.This cross effect provides a new method to study the magnetization dynamics and paves a way for novel cavity magnonic devices by including the heating effect as an operational degree of freedom.
文摘A magnonic counterpart to optical frequency combs is vital for high-precision magnonic frequency metrology and spectroscopy.Here,we present an efficient mechanism for the generation of robust magnonic frequency combs in a yttrium iron garnet(YIG)sphere via magnetostrictive effects.We show that magnonic and vibrational dynamics in the ferrimagnetic sphere can be substantively modified in the presence of magnetostrictive effects,which results in degenerate and non-degenerate magnonic four-wave mixing and frequency conversion.Particularly,resonantly enhanced magnetostrictive effects can induce phonon laser action above a threshold,which leads to significant magnonic nonlinearity and enables a potentially practical scheme for the generation of robust magnonic frequency combs.Numerical calculations of both magnonic and phononic dynamics show excellent agreement with this theory.These results deepen our understanding of magnetostrictive interaction,open a novel and efficient pathway to realize magnonic frequency conversion and mixing in a magnonic device,and provide a sensitive tool for precision measurement.
基金support from the National Natural Science Foundation of China(Grant Nos.62131002 and 62071448)and the Fundamental Research Funds for the Central Universities(BNU).
文摘Recently,the photon–magnon coherent interaction based on the collective spins excitation in ferromagnetic materials has been achieved experimentally.Under the prospect,the magnons are proposed to store and process quantum information.Meanwhile,cavity-optomagnonics which describes the interaction between photons and magnons has been developing rapidly as an interesting topic of the cavity quantum electrodynamics.Here in this short review,we mainly introduce the recent theoretical and experimental progress in the field of optomagnetic coupling and optical manipulation based on cavity-optomagnonics.According to the frequency range of the electromagnetic field,cavity optomagnonics can be divided into microwave cavity optomagnonics and optical cavity optomagnonics,due to the different dynamics of the photon–magnon interaction.As the interaction between the electromagnetic field and the magnetic materials is enhanced in the cavity-optomagnonic system,it provides great significance to explore the nonlinear characteristics and quantum properties for different magnetic systems.More importantly,the electromagnetic response of optomagnonics covers the frequency range from gigahertz to terahertz which provides a broad frequency platform for the multi-mode controlling in quantum systems.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0301200)the National Natural Science Foundation of China(Grant Nos.11774022,and U1530401)
文摘We develop a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet(YIG) sphere strongly coupled to cavity photons, and use it to study the bistability in this hybrid system. To have a complete picture of the bistability phenomenon, we analyze two different cases in driving the cavity magnonics system, i.e.,directly pumping the YIG sphere and the cavity, respectively. In both cases, the magnon frequency shifts due to the Kerr effect exhibit a similar bistable behavior but the corresponding critical powers are different. Moreover, we show how the bistability of the system can be demonstrated using the transmission spectrum of the cavity. Our results are valid in a wide parameter regime and generalize the theory of bistability in a cavity magnonics system.
基金Project supported by the National Key R&D Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12334008, 12174441,12134020, and 12374156)。
文摘Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method.We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single-and two-magnon excitations,respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.
基金Project supported by the National Natural Science Foundation of China(Grant No.12064011)the Natural Science Fund Project of Hunan Province(Grant No.2020JJ4498)the Graduate Research Innovation Foundation of Jishou University(Grant No.Jdy21030).
文摘This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya interaction.Using a first-order Green function method,we analyze the influence of magnon-magnon interaction on the magnon band topology.We find that Chern numbers of two renormalized magnon bands are different above and below the critical temperature,which means that the magnon band gap-closing phenomenon is an indicator for one topological phase transition of the checkerboard ferromagnet.Our results show that the checkerboard ferromagnet possesses two topological phases,and its topological phase can be controlled either via the temperature or the applied magnetic field due to magnon-magnon interactions.Interestingly,it is found that the topological phase transition can occur twice with the increase in the temperature,which is different from the results of the honeycomb ferromagnet.
基金The project was funded by the European Research Council(ERC)Starting Grant 678309 MagnonCircuits and the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-TRR 173-268565370(“Spin+X”,Project B01)the Nachwuchsring of the TU KaiserslauternR.V.acknowledges support of National Research Foundation of Ukraine(grant number 2020.02/0261).
文摘The field of magnonics,which aims at using spin waves as carriers in data-processing devices,has attracted increasing interest in recent years.We present and study micromagnetically a nonlinear nanoscale magnonic ring resonator device for enabling implementations of magnonic logic gates and neuromorphic magnonic circuits.In the linear regime,this device efficiently suppresses spin-wave transmission using the phenomenon of critical resonant coupling,thus exhibiting the behavior of a notch filter.By increasing the spin-wave input power,the resonance frequency is shifted,leading to transmission curves,depending on the frequency,reminiscent of the activation functions of neurons,or showing the characteristics of a power limiter.An analytical theory is developed to describe the transmission curve of magnonic ring resonators in the linear and nonlinear regimes,and is validated by a comprehensive micromagnetic study.The proposed magnonic ring resonator provides a multi-functional nonlinear building block for unconventional magnonic circuits.
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Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0300801)the National Natural Science Foundation of China(Grant Nos.51702042,61734002,61571079,51572042,and 61471096)+1 种基金the International Science&Technology Cooperation Program of China(Grant No.2015DFR50870)the Sichuan Science and Technology Support Project,China(Grant Nos.2016GZ0250 and 2017JY0002)
文摘Liquid phase epitaxy (LPE) is a mature technology. Early experiments on single magnetic crystal films fabricated by LPE were focused mainly on thick films for microwave and magneto-optical devices. The LPE is an excellent way to make a thick film, low damping magnetic garnet film and high-quality magneto-optical material. Today, the principal challenge in the applied material is to create sub-micrometer devices by using modern photolithography technique. Until now the magnetic garnet films fabricated by LPE still show the best quality even on a nanoscale (about 100 nm), which was considered to be impossible for LPE method.
基金Project supported by Beijing Natural Science Foundation,China(Grant No.JQ18014)the National Natural Science Foundation of China(Grant No.12074371)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000),and CAS Interdisciplinary Innovation Team.
文摘Ultrathin van der Waals(vdW)magnets provide a possibility to access magnetic ordering in the two-dimensional(2D)limit,which are expected to be applied in the spintronic devices.Raman spectroscopy is a powerful characterization method to investigate the spin-related properties in 2D vdW magnets,including magnon and spin–lattice interaction,which are hardly accessible by other optical methods.In this paper,the recent progress of various magnetic properties in 2D vdW magnets studied by Raman spectroscopy is reviewed,including the magnetic transition,spin-wave,spin–lattice interaction,symmetry tuning induced by spin ordering,and nonreciprocal magneto-phonon Raman scattering.
基金Supported by the National Natural Science Foundation of China (Grant Nos.51871235,51671212,52031014,51771198,and51801212)the National Key Research and Development Program of China (Grant Nos.2016YFA0300701,2017YFB0702702,and2017YA0206302)+2 种基金the Key Research Program of Frontier Sciences,CAS (Grant Nos.QYZDJ-SSW-JSC023,KJZD-SW-M01ZDYZ2012-2)support from the Natural Science Foundation for Distinguished Young Scholars of Hebei Province of China (S&T Program of Hebei,Grant No.A2019205310)。
文摘Magnon-magnon coupling in synthetic antiferromagnets advances it as hybrid magnonic systems to explore the quantum information technologies.To induce magnon-magnon coupling,the parity symmetry between two magnetization needs to be broken.Here we experimentally demonstrate a convenient method to break the parity symmetry by the asymmetric structure.We successfully introduce a magnon-magnon coupling in Ir-based synthetic antiferromagnets CoFeB(10 nm)/Ir(t_(Ir)=0.6 nm,1.2 nm)/CoFeB(13 nm).Remarkably,we find that the weakly uniaxial anisotropy field(-20 Oe)makes the magnon-magnon coupling anisotropic.The coupling strength presented by a characteristic anticrossing gap varies in the range between 0.54 GHz and 0.90 GHz for t_(Ir)=0.6 nm,and between 0.09 GHz and 1.4 GHz for t_(Ir)=1.2 nm.Our results demonstrate a feasible way to induce magnon-magnon coupling by an asymmetric structure and tune the coupling strength by varying the direction of in-plane magnetic field.The magnon-magnon coupling in this highly tunable material system could open exciting perspectives for exploring quantum-mechanical coupling phenomena.
基金This work was supported by 2000 Hundred Talents Program project of Chinese Academy of Sciences and 973 project with Grant No. 2001CB610601 of PRC Ministry of Science and Technology. X.F.Han also gratefully acknowledges the partial support of K.C.Wong Edu
文摘An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2/|TJ|2 ) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe21(25 nm)/lr22Mn78(12 nm)/Co75Fe25(4 nm)/AI(0.8 nm)-oxide/Co75Fe25(4 nm)/Ni79Fe21(20 nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.
基金Project supported by the National Natural Science Foundation of China(Grant No.61604106)Shandong Provincial Natural Science Foundation,China(Grant No.ZR2014FL025)
文摘The topological magnon insulator on a honeycomb lattice with Dzyaloshinskii–Moriya interaction(DMI) is studied under the application of a circularly polarized light.At the high-frequency regime, the effective tight-binding model is obtained based on Brillouin–Wigner theory.Then, we study the corresponding Berry curvature and Chern number.In the Dirac model, the interplay between a light-induced handedness-dependent effective DMI and intrinsic DMI is discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.51331006)the Fund from the Chinese Academy of Sciences(Grant No.KJZD-EW-M05)
文摘Skyrmions are very promising for applications in spintronics and magnetic memory.It is desired to manipulate and operate a single skyrmion.Here we report on the thermal effect on the motion of current-driven magnetic Skyrmions in magnetic metal.The results show that the magnon current induced by the thermal gradient acts on Skyrmions via magnonic spin-transfer torque,an effect of the transverse and longitudinal Skyrmions drift velocities,thus leading to the effective manipulation of the Hall angle through the ratio of thermal gradient to electric current density,which can be used as a Skyrmion valve.
基金Project supported by the Foundation for Key Program of Ministry of Education,China (Grant No 206024)National Natural Science Foundation of China (Grant No 10762001)+2 种基金Program for New Century Excellent Talents in University of China (Grant NoNCET-05-0272)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No 20040126003)Natural Science Foundation of Inner Mongolia Autonomous Region,China (Grant No 200711020109)
文摘The eigenprobtems of spin waves in a symmetrical ferromagnetic bilayered system with periodic boundary conditions are solved using the interface-rescaling approach (IRA). The results show that interface coupling between two sublayers would not change the excitation energy of odd bulk modes, but change excitation energy of even bulk modes. We call this peculiar phenomenon the phenomenon of even bulk mode variance (PEBMV). There are two kinds of mechanisms which cause PEBMV: phase reversal and phase translation of the magnon at the interface, corresponding, respectively, to the antiferromagnetic and ferromagnetic interface coupling cases. PEBMV embodies the selective effect of the interface on different bulk magnons.
文摘Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.