Magnetic skyrmions are recognized as potential information carriers for building the next-generation spintronic memory and logic devices.Towards functional device applications,efficient electrical detection of skyrmio...Magnetic skyrmions are recognized as potential information carriers for building the next-generation spintronic memory and logic devices.Towards functional device applications,efficient electrical detection of skyrmions at room temperature is one of the most important prerequisites.展开更多
The skyrmion generator is one of the indispensable components for the future functional skyrmion devices,but the process of generating skyrmion cannot avoid mixing with other magnetic textures,such as skyrmionium and ...The skyrmion generator is one of the indispensable components for the future functional skyrmion devices,but the process of generating skyrmion cannot avoid mixing with other magnetic textures,such as skyrmionium and nested skyrmion bags.These mixed magnetic textures will inevitably lead to the blockage of skyrmion transport and even the distortion of data information.Therefore,the design of an efficient skyrmion filter is of great significance for the development of skyrmion-based spintronic devices.In this work,a skyrmion filter scheme is proposed,and the high-efficiency filtering function is demonstrated by micromagnetic simulations.The results show that the filtering effect of the scheme depends on the structure geometry and the spin current density that drives the skyrmion.Based on this scheme,the polarity of the filtered skyrmion can be controlled by switching the magnetization state at the output end,and the“cloning”of the skyrmion can be realized by geometric optimization of the structure.We believe that in the near future,the skyrmion filter will become one of the important components of skyrmion-based spintronic devices in the future.展开更多
We study the stability and dynamic behaviors of skyrmions in magnetic nanotubes,where curvature and cylindrical symmetry provide unique mechanisms for skyrmion formation and control.Unlike planar geometries,skyrmions ...We study the stability and dynamic behaviors of skyrmions in magnetic nanotubes,where curvature and cylindrical symmetry provide unique mechanisms for skyrmion formation and control.Unlike planar geometries,skyrmions confined in nanotubes exhibit elliptical shapes,stabilized through the interplay of curvature-induced effects,Dzyaloshinskii-Moriya interaction(DMI),and magnetic anisotropy.Using micromagnetic simulations,we construct phase diagrams of skyrmion stability as functions of DMI strength and anisotropy,identifying transitions to saturated or helical configurations in unstable regimes.The dynamics reveal distinct counterclockwise gyration modes,strongly influenced by tube geometry and applied microwave fields.We find that external magnetic fields significantly enhance the azimuthal velocity(v_(φ))while maintaining a consistent axial motion(v_(z))along the-z-direction.Furthermore,transitions between gyration and linear translation modes emerge,governed by the combined effects of magnetic field,DMI,and curvature.Notably,the skyrmion's motion direction depends on the excitation mode and DMI sign,while curvature-modified spin textures produce effective fields without conventional pinning.These results demonstrate that magnetic nanotubes offer a robust and tunable platform for skyrmion manipulation,with potential applications in next-generation memory and logic devices.Our findings also highlight the role of curvature in enabling stable and controllable topological spin textures for advanced spintronic technologies.展开更多
Spin waves,quantized as magnons,constitute a fundamental class of excitations and serve as one of the primary angular momentum carriers in magnetic systems.Devoid of Joule heating,a magnonic device that routes spin wa...Spin waves,quantized as magnons,constitute a fundamental class of excitations and serve as one of the primary angular momentum carriers in magnetic systems.Devoid of Joule heating,a magnonic device that routes spin waves between different ports holds promise for an energy-efficient information infrastructure.Here,we systematically investigate the transport behavior of a magnetic skyrmion-based magnon circulator,a representative device that directs spin wave flow in a non-reciprocal manner.Particularly,a ballistic transport model is established,where the scattering of spin waves by magnetic skyrmions is simplified as magnon deflection by fictitious electromagnetic fields within the skyrmions.Through the combination of ballistic analyses and micromagnetic simulations,the circulation performance is rigorously evaluated for multiple magnon circulators.展开更多
Understanding skyrmion–skyrmion interactions and their dynamical effects is crucial for skyrmion-based applications.In this article,we investigate the deformation of skyrmions induced by the inter-skyrmion interactio...Understanding skyrmion–skyrmion interactions and their dynamical effects is crucial for skyrmion-based applications.In this article,we investigate the deformation of skyrmions induced by the inter-skyrmion interaction in both static and dynamic scenarios for a two-skyrmion system.In the static case under a pinning magnetic field,the inter-skyrmion interaction energy decreases rapidly with increasing separation between the skyrmions,while their individual sizes grow.The semiaxis ratio of the elliptical skyrmion exhibits non-monotonic behavior,owing to the competition between skyrmion–skyrmion interactions and pinning effects.In dynamic simulations after removing the external pinning field,the two skyrmions spiral away from each other with increasing separation.Following a rapid relaxation period after magnetic field withdrawal,their semiaxis ratio typically increases with distance and the skyrmions gradually approach a perfect circular shape.These findings provide valuable insights into the behavior and interactions of two-skyrmion systems.展开更多
Distortion of skyrmions arouses much attention recently due to the exotic topologic al and dynamic properties.Investigating the formation mechanism and dynamical behavior of the deformed skyrmions promotes practical s...Distortion of skyrmions arouses much attention recently due to the exotic topologic al and dynamic properties.Investigating the formation mechanism and dynamical behavior of the deformed skyrmions promotes practical spintronic applications.Elongation,as a typical form of deformation,has been discovered both in experiments and in theories.However,the intrinsic mechanism is absent.Here,the coexistence of zero-field circular and elongated skyrmions in helimagnetic films is observed.The elongated skyrmions,which are determined by the intrinsic Dzyaloshinskii-Moriya interaction(DMI),carry the same topological charge as the circular ones and show the skyrmion Hall effect.Currentdriven dynamics reveal again the significant role of the intrinsic DMI playing in the skyrmion elongation.展开更多
A magnetic skyrmion is a particle-like spin swirling object with a nontrivial topology that holds great promise for next-generation information carriers in highperformance spintronic devices.It was discovered in a chi...A magnetic skyrmion is a particle-like spin swirling object with a nontrivial topology that holds great promise for next-generation information carriers in highperformance spintronic devices.It was discovered in a chiral magnet,MnSi with B20 structure,in 2009 and later confirmed as a common feature of magnetic compounds with Dzyaloshinsky-Moriya interaction(DMI).In this work,we provide fundamental insight into the magnetic properties of skyrmion-hosting materials originating from DMI.The relationship between the point groups of the materials and DMI is introduced;then,the common features of magnetic skyrmions experimentally verified in the magnetization and magnetotransport measurements are highlighted.Finally,other particle-like magnetic configurations in chiral magnets and the crossover with a superconductor are discussed.展开更多
Magnetic skyrmions,the topological spin textures firstly observed in chiral magnets,have aroused huge interest due to their emergent electromagnetism and potential applications in spintronics.Over the last decade,sign...Magnetic skyrmions,the topological spin textures firstly observed in chiral magnets,have aroused huge interest due to their emergent electromagnetism and potential applications in spintronics.Over the last decade,significant efforts have been devoted to skyrmion generation,stabilization,and dynamics.In most cases,the theoretical and experimental investigations have been performed in the materials where the skyrmions have a circular shape.As we know,magnetic anisotropy(K_(u))and Dzyaloshinskii-Moriya interaction(DMI)play key roles in the stabilization of the skyrmions in chiral magnets.Therefore,modifying the Kand DMI provide new degrees of freedom for studying the related physics and applications of skyrmions in addition to engineering their energetics and sizes.In this review,the latest progress on the study of the anisotropic deformation of magnetic skyrmions(i.e.,elliptical magnetic skyrmions)is summarized.The physical origins and important advantages of elliptical magnetic skyrmions are mainly focused on.This review gives an insight into the understanding of the physical mechanisms of elliptical magnetic skyrmion-hosting systems.展开更多
Compared with the traditional magnetic bubble,a skyrmion has a smaller size,and better stability and therefore is considered as a very promising candidate for future memory devices.When skyrmions are manipulated,erase...Compared with the traditional magnetic bubble,a skyrmion has a smaller size,and better stability and therefore is considered as a very promising candidate for future memory devices.When skyrmions are manipulated,erased and created,the density of skyrmions can be varied,however the relationship between the radii and the densities of skyrmions needs more exploration.In this paper,we study this problem both theoretically and by using the lattice simulation.The average radius of skyrmions as a function of material parameters,the strength of the external magnetic field and the density of skyrmions is obtained and verified.With this explicit function,the skyrmion radius can be easily predicted,which is helpful for the future study of skyrmion memory devices.展开更多
Voltage-controlled magnetic skyrmions have attracted special attention because they satisfy the requirements for well-controlled high-efficiency and energy saving for future skyrmion-based neuron device applications.I...Voltage-controlled magnetic skyrmions have attracted special attention because they satisfy the requirements for well-controlled high-efficiency and energy saving for future skyrmion-based neuron device applications.In this work,we propose a compact leaky-integrate-fire(LIF)spiking neuron device by using the voltage-driven skyrmion dynamics in a multiferroic nanodisk structure.The skyrmion dynamics is controlled by well tailoring voltage-induced piezostrains,where the skyrmion radius can be effectively modulated by applying the piezostrain pulses.Like the biological neuron,the proposed skyrmionic neuron will accumulate a membrane potential as skyrmion radius is varied by inputting the continuous piezostrain spikes,and the skyrmion radius will return to the initial state in the absence of piezostrain.Therefore,this skyrmion radius-based membrane potential will reach a definite threshold value by the strain stimuli and then reset by removing the stimuli.Such the LIF neuronal functionality and the behaviors of the proposed skyrmionic neuron device are elucidated through the micromagnetic simulation studies.Our results may benefit the utilization of skyrmionic neuron for constructing the future energy-efficient and voltage-tunable spiking neural networks.展开更多
In curved geometries,a lot of novel curvaturedriven effects are discovered due to the curvature-induced effective anisotropy and Dzyaloshinskii-Moriya interaction.Curvature effect also provides means to modify convent...In curved geometries,a lot of novel curvaturedriven effects are discovered due to the curvature-induced effective anisotropy and Dzyaloshinskii-Moriya interaction.Curvature effect also provides means to modify conventional results and launch new functionalities in study of magnetic skyrmions.Magnetic skyrmions are particle-like spin textures with topological protections.It has been found in several magnetic materials and has been one of the research hotspots in magnetism and spintronics as the carriers of information.BothDzyaloshinskii-Moriya interaction and anisotropy have significant effects on the formation and stability of magnetic skyrmions.The magnetic skyrmions in curved geometries show some novel characteristics,and the study in this field may promote the development of magnetic skyrmions.This article provides a review of the present state of the research on skyrmions in curved geometries including curved nanotracks,thin films with curved defect,nanotubes,spherical and hemispherical shells.The reviewmainly covers three aspects,the formation and stability of skyrmions,the shape and size of skyrmions,and the dynamical behaviors of skyrmions in curved geometries.展开更多
Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for nex...Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for next-generation magnetic memory devices.Lorentz transmission electron microscopy(TEM)has an ultrahigh magnetic domain resolution(~2 nm),it is thus an ideal method for direct real-space imaging of fine magnetic configurations of ultra-small skyrmions.In this paper,we describe the basic principles of Lorentz-TEM and off-axis electron holography and review recent experimental developments in magnetic skyrmion imaging using these two methods.展开更多
Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various asp...Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.展开更多
A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small ...A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small thickness,an easy-plane anisotropy in the Fe Ge layer is taken into account,and the skyrmion-crystal state is favored to appear for low anisotropies and intermediate Fe Ge/Ni interlayer exchange couplings,and finally transformed from a labyrinth-like and into an out-ofplane uniform state for the large couplings or into an in-plane state for the high anisotropies.Furthermore,the maximum skyrmion charge number is bigger for the periodic and fixed boundary conditions with an out-of-plane magnetization;on the contrary,the Bloch-type skyrmions can be frozen and stabilized for the larger couplings on the fixed boundary with an in-plane magnetization,similar to the experimental results of the magnetic-field-induced skyrmions.Finally,the skyrmion charge number and diameter both decrease if the nonmagnetic defects exist,and the skyrmion centers are prone to being captured by defect sites.This work evidences that the ensembles of homochiral skyrmions stabilized in the multilayers fabricated by well-established technologies present a roadmap to design new classes of the materials that can host skyrmions.展开更多
Within the magnonics community,there has been a lot of interests in the magnon–skyrmion interaction.Magnons and skyrmions are two intriguing phenomena in condensed matter physics,and magnetic nanotubes have emerged a...Within the magnonics community,there has been a lot of interests in the magnon–skyrmion interaction.Magnons and skyrmions are two intriguing phenomena in condensed matter physics,and magnetic nanotubes have emerged as a suitable platform to study their complex interactions.We show that magnon frequency combs can be induced in magnetic nanotubes by three-wave mixing between the propagating magnons and skyrmion.This study enriches our fundamental comprehension of magnon–skyrmion interactions and holds promise for developing innovative spintronic devices and applications.This frequency comb tunability and unique spectral features offer a rich platform for exploring novel avenues in magnetic nanotechnology.展开更多
We investigate the skyrmion motion driven by spin waves on magnetic nanotubes through micromagnetic simulations.Our key results include demonstrating the stability and enhanced mobility of skyrmions on the edgeless na...We investigate the skyrmion motion driven by spin waves on magnetic nanotubes through micromagnetic simulations.Our key results include demonstrating the stability and enhanced mobility of skyrmions on the edgeless nanotube geometry,which prevents destruction at boundaries—a common issue in planar geometries.We explore the influence of the damping coefficient,amplitude,and frequency of microwaves on skyrmion dynamics,revealing a non-uniform velocity profile characterized by acceleration and deceleration phases.Our results show that the skyrmion Hall effect is significantly modulated on nanotubes compared to planar models,with specific dependencies on the spin-wave parameters.These findings provide insights into skyrmion manipulation for spintronic applications,highlighting the potential for high-speed and efficient information transport in magnonic devices.展开更多
The magnetic skyrmion transport driven by pure voltage-induced strain gradient is proposed and studied via micromagnetic simulation.Through combining the skyrmion with multiferroic heterojunction,a voltage-induced uni...The magnetic skyrmion transport driven by pure voltage-induced strain gradient is proposed and studied via micromagnetic simulation.Through combining the skyrmion with multiferroic heterojunction,a voltage-induced uniaxial strain gradient is adjusted to move skyrmions.In the system,a pair of short-circuited trapezoidal top electrodes can generate the symmetric strain.Due to the symmetry of strain,the magnetic skyrmion can be driven with a linear motion in the middle of the nanostrip without deviation.We calculate the strain distribution generated by the trapezoidal top electrodes pair,and further investigate the influence of the strain intensity as well as the strain gradient on the skyrmion velocity.Our findings provide a stable and low-energy regulation method for skyrmion transport.展开更多
基金supported by the National Key R&D Program of China(Grant No.2022YFA1405100)the NSFC distinguished Young Scholar program(Grant No.12225409)+6 种基金the Basic Science Center Project of National Natural Science Foundation of China(NSFC)(Grant No.52388201)the NSFC general program(Grant Nos.52271181,51831005,and 12421004)the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300500)Beijing Natural Science Foundation(Grant No.Z240006)supported by the KAUST Office of Sponsored Research(OSR)under Award Nos.ORA-CRG102021-4665 and ORA-CRG11-2022-5031supported by the National Key Research and Development Program of China(No.2024YFA1408503)Sichuan Province Science and Technology Support Program(No.2025YFHZ0147)。
文摘Magnetic skyrmions are recognized as potential information carriers for building the next-generation spintronic memory and logic devices.Towards functional device applications,efficient electrical detection of skyrmions at room temperature is one of the most important prerequisites.
基金supported by the National Natural Science Foundation of China(Grant No.12364020)the Scientific and Technological Development Plan of Jilin Province,China(Grant No.20240101295JC)+1 种基金the Science and Technology Research and Planning Project of Jilin Provincial Department of Education(Grant No.JJKH20230611KJ)the Applied Foundation Research Project(Talent Funding Project)of Yanbian University(Grant No.ydkj202241).
文摘The skyrmion generator is one of the indispensable components for the future functional skyrmion devices,but the process of generating skyrmion cannot avoid mixing with other magnetic textures,such as skyrmionium and nested skyrmion bags.These mixed magnetic textures will inevitably lead to the blockage of skyrmion transport and even the distortion of data information.Therefore,the design of an efficient skyrmion filter is of great significance for the development of skyrmion-based spintronic devices.In this work,a skyrmion filter scheme is proposed,and the high-efficiency filtering function is demonstrated by micromagnetic simulations.The results show that the filtering effect of the scheme depends on the structure geometry and the spin current density that drives the skyrmion.Based on this scheme,the polarity of the filtered skyrmion can be controlled by switching the magnetization state at the output end,and the“cloning”of the skyrmion can be realized by geometric optimization of the structure.We believe that in the near future,the skyrmion filter will become one of the important components of skyrmion-based spintronic devices in the future.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1405900)the National Natural Science Foundation of China(Grant Nos.U2441217 and 12074058)Sichuan Science and Technology Program(Grant No.2024YFHZ0372)。
文摘We study the stability and dynamic behaviors of skyrmions in magnetic nanotubes,where curvature and cylindrical symmetry provide unique mechanisms for skyrmion formation and control.Unlike planar geometries,skyrmions confined in nanotubes exhibit elliptical shapes,stabilized through the interplay of curvature-induced effects,Dzyaloshinskii-Moriya interaction(DMI),and magnetic anisotropy.Using micromagnetic simulations,we construct phase diagrams of skyrmion stability as functions of DMI strength and anisotropy,identifying transitions to saturated or helical configurations in unstable regimes.The dynamics reveal distinct counterclockwise gyration modes,strongly influenced by tube geometry and applied microwave fields.We find that external magnetic fields significantly enhance the azimuthal velocity(v_(φ))while maintaining a consistent axial motion(v_(z))along the-z-direction.Furthermore,transitions between gyration and linear translation modes emerge,governed by the combined effects of magnetic field,DMI,and curvature.Notably,the skyrmion's motion direction depends on the excitation mode and DMI sign,while curvature-modified spin textures produce effective fields without conventional pinning.These results demonstrate that magnetic nanotubes offer a robust and tunable platform for skyrmion manipulation,with potential applications in next-generation memory and logic devices.Our findings also highlight the role of curvature in enabling stable and controllable topological spin textures for advanced spintronic technologies.
基金supported by the National Natural Science Foundation of China(Grant Nos.12374117 and 11904260)the Natural Science Foundation of Tianjin(Grant No.20JCQNJC02020)。
文摘Spin waves,quantized as magnons,constitute a fundamental class of excitations and serve as one of the primary angular momentum carriers in magnetic systems.Devoid of Joule heating,a magnonic device that routes spin waves between different ports holds promise for an energy-efficient information infrastructure.Here,we systematically investigate the transport behavior of a magnetic skyrmion-based magnon circulator,a representative device that directs spin wave flow in a non-reciprocal manner.Particularly,a ballistic transport model is established,where the scattering of spin waves by magnetic skyrmions is simplified as magnon deflection by fictitious electromagnetic fields within the skyrmions.Through the combination of ballistic analyses and micromagnetic simulations,the circulation performance is rigorously evaluated for multiple magnon circulators.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12175180,11934015,and12247103,Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant Nos.22JSZ005 and22JSQ041)the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.2024JC-YBMS-022)。
文摘Understanding skyrmion–skyrmion interactions and their dynamical effects is crucial for skyrmion-based applications.In this article,we investigate the deformation of skyrmions induced by the inter-skyrmion interaction in both static and dynamic scenarios for a two-skyrmion system.In the static case under a pinning magnetic field,the inter-skyrmion interaction energy decreases rapidly with increasing separation between the skyrmions,while their individual sizes grow.The semiaxis ratio of the elliptical skyrmion exhibits non-monotonic behavior,owing to the competition between skyrmion–skyrmion interactions and pinning effects.In dynamic simulations after removing the external pinning field,the two skyrmions spiral away from each other with increasing separation.Following a rapid relaxation period after magnetic field withdrawal,their semiaxis ratio typically increases with distance and the skyrmions gradually approach a perfect circular shape.These findings provide valuable insights into the behavior and interactions of two-skyrmion systems.
基金financially supported by the National Natural Science Foundation of China(Nos.51701217,51590883 and 52031014)。
文摘Distortion of skyrmions arouses much attention recently due to the exotic topologic al and dynamic properties.Investigating the formation mechanism and dynamical behavior of the deformed skyrmions promotes practical spintronic applications.Elongation,as a typical form of deformation,has been discovered both in experiments and in theories.However,the intrinsic mechanism is absent.Here,the coexistence of zero-field circular and elongated skyrmions in helimagnetic films is observed.The elongated skyrmions,which are determined by the intrinsic Dzyaloshinskii-Moriya interaction(DMI),carry the same topological charge as the circular ones and show the skyrmion Hall effect.Currentdriven dynamics reveal again the significant role of the intrinsic DMI playing in the skyrmion elongation.
基金financially supported by the Key Research Program of Frontier Sciences,CAS(No.QYZDBSSW-SLH009)the Key Research Program of the Chinese Academy of Sciences(No.KJZD-SW-M01)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB33030100)the Equipment Development Project of Chinese Academy of Sciences(No.YJKYYQ20180012)the Natural Science Foundation of China(No.11904368)the Natural Science Foundation of Anhui Province(No.2008085QA32)supported by the High Magnetic Field Laboratory of Anhui Province。
文摘A magnetic skyrmion is a particle-like spin swirling object with a nontrivial topology that holds great promise for next-generation information carriers in highperformance spintronic devices.It was discovered in a chiral magnet,MnSi with B20 structure,in 2009 and later confirmed as a common feature of magnetic compounds with Dzyaloshinsky-Moriya interaction(DMI).In this work,we provide fundamental insight into the magnetic properties of skyrmion-hosting materials originating from DMI.The relationship between the point groups of the materials and DMI is introduced;then,the common features of magnetic skyrmions experimentally verified in the magnetization and magnetotransport measurements are highlighted.Finally,other particle-like magnetic configurations in chiral magnets and the crossover with a superconductor are discussed.
基金financially supported by Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110553)Science Center of the National Science Foundation of China(No.52088101)+5 种基金Beijing Natural Science Foundation(No.Z190009)the National Natural Science Foundation of China(NSFC,Nos.11874409 and 11904056)K.C.Wong Education Foundation(No.GJTD-2019-14)China Postdoctoral Science Foundation(No.2020M670499)Guangzhou basic and applied basic research project(No.202102020053)the startup funding from Songshan Lake Materials Laboratory(No.Y1D1071S511)。
文摘Magnetic skyrmions,the topological spin textures firstly observed in chiral magnets,have aroused huge interest due to their emergent electromagnetism and potential applications in spintronics.Over the last decade,significant efforts have been devoted to skyrmion generation,stabilization,and dynamics.In most cases,the theoretical and experimental investigations have been performed in the materials where the skyrmions have a circular shape.As we know,magnetic anisotropy(K_(u))and Dzyaloshinskii-Moriya interaction(DMI)play key roles in the stabilization of the skyrmions in chiral magnets.Therefore,modifying the Kand DMI provide new degrees of freedom for studying the related physics and applications of skyrmions in addition to engineering their energetics and sizes.In this review,the latest progress on the study of the anisotropic deformation of magnetic skyrmions(i.e.,elliptical magnetic skyrmions)is summarized.The physical origins and important advantages of elliptical magnetic skyrmions are mainly focused on.This review gives an insight into the understanding of the physical mechanisms of elliptical magnetic skyrmion-hosting systems.
基金partially supported by the National Natural Science Foundation of China under Grant No.12047570the Natural Science Foundation of the Liaoning Scientific Committee Grant No.2019-BS-154。
文摘Compared with the traditional magnetic bubble,a skyrmion has a smaller size,and better stability and therefore is considered as a very promising candidate for future memory devices.When skyrmions are manipulated,erased and created,the density of skyrmions can be varied,however the relationship between the radii and the densities of skyrmions needs more exploration.In this paper,we study this problem both theoretically and by using the lattice simulation.The average radius of skyrmions as a function of material parameters,the strength of the external magnetic field and the density of skyrmions is obtained and verified.With this explicit function,the skyrmion radius can be easily predicted,which is helpful for the future study of skyrmion memory devices.
基金the National Natural Science Foundation of China(Grant Nos.11902316,51902300,and 11972333)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LQ19F010005,LY21F010011,and LZ19A020001).
文摘Voltage-controlled magnetic skyrmions have attracted special attention because they satisfy the requirements for well-controlled high-efficiency and energy saving for future skyrmion-based neuron device applications.In this work,we propose a compact leaky-integrate-fire(LIF)spiking neuron device by using the voltage-driven skyrmion dynamics in a multiferroic nanodisk structure.The skyrmion dynamics is controlled by well tailoring voltage-induced piezostrains,where the skyrmion radius can be effectively modulated by applying the piezostrain pulses.Like the biological neuron,the proposed skyrmionic neuron will accumulate a membrane potential as skyrmion radius is varied by inputting the continuous piezostrain spikes,and the skyrmion radius will return to the initial state in the absence of piezostrain.Therefore,this skyrmion radius-based membrane potential will reach a definite threshold value by the strain stimuli and then reset by removing the stimuli.Such the LIF neuronal functionality and the behaviors of the proposed skyrmionic neuron device are elucidated through the micromagnetic simulation studies.Our results may benefit the utilization of skyrmionic neuron for constructing the future energy-efficient and voltage-tunable spiking neural networks.
基金financially supported by the National Natural Science Foundation of China (No. 11774045)Liaoning Revitalization Talents Program (No. XLYC2007150)
文摘In curved geometries,a lot of novel curvaturedriven effects are discovered due to the curvature-induced effective anisotropy and Dzyaloshinskii-Moriya interaction.Curvature effect also provides means to modify conventional results and launch new functionalities in study of magnetic skyrmions.Magnetic skyrmions are particle-like spin textures with topological protections.It has been found in several magnetic materials and has been one of the research hotspots in magnetism and spintronics as the carriers of information.BothDzyaloshinskii-Moriya interaction and anisotropy have significant effects on the formation and stability of magnetic skyrmions.The magnetic skyrmions in curved geometries show some novel characteristics,and the study in this field may promote the development of magnetic skyrmions.This article provides a review of the present state of the research on skyrmions in curved geometries including curved nanotracks,thin films with curved defect,nanotubes,spherical and hemispherical shells.The reviewmainly covers three aspects,the formation and stability of skyrmions,the shape and size of skyrmions,and the dynamical behaviors of skyrmions in curved geometries.
基金Project supported by the National Key Research and Development Program of China,(Grant No.2017YFA0303201)the Key Research Program of Frontier Sciences,CAS,(Grant No.QYZDB-SSW-SLH009)+2 种基金the National Natural Science Foundation of China(Grant Nos.51622105 and 11804343)the President Foundation of Hefei Institutes of Physical Science,CAS(Grant No.YZJJ2018QN15)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology,(Grant No.2016FXCX001)
文摘Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for next-generation magnetic memory devices.Lorentz transmission electron microscopy(TEM)has an ultrahigh magnetic domain resolution(~2 nm),it is thus an ideal method for direct real-space imaging of fine magnetic configurations of ultra-small skyrmions.In this paper,we describe the basic principles of Lorentz-TEM and off-axis electron holography and review recent experimental developments in magnetic skyrmion imaging using these two methods.
基金financially supported by the National Natural Science Foundation of China (Nos. 51771127, 52171188 52111530143, 12104327, 51901081, 11974298 and 61961136006)the National Key Research and Development Program of China (No. 2020YFA0309300)+6 种基金Sichuan Science and Technology Program (Application No. 21ZYZYTS0077)the Science and Technology Program of Guangzhou (No. 202002030052)Guangdong Special Support Project (No. 2019BT02X030)Shenzhen Fundamental Research Fund (No. JCYJ20210324120213037)Shenzhen Peacock Group Plan (No. KQTD20180413181702403)Pearl River Recruitment Program of Talents (No. 2017GC010293)the Grants-in-Aid for Scientific Research from JSPS KAKENHI (Nos. JP20F20363, JP21H01364 and JP21K18872)
文摘Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.
基金the National Natural Science Foundation of China(Grant No.11774045)the Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(Grant No.20180510008)the Fundamental Research Funds for Central Universities,China(Grant No.N182410008-1)。
文摘A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small thickness,an easy-plane anisotropy in the Fe Ge layer is taken into account,and the skyrmion-crystal state is favored to appear for low anisotropies and intermediate Fe Ge/Ni interlayer exchange couplings,and finally transformed from a labyrinth-like and into an out-ofplane uniform state for the large couplings or into an in-plane state for the high anisotropies.Furthermore,the maximum skyrmion charge number is bigger for the periodic and fixed boundary conditions with an out-of-plane magnetization;on the contrary,the Bloch-type skyrmions can be frozen and stabilized for the larger couplings on the fixed boundary with an in-plane magnetization,similar to the experimental results of the magnetic-field-induced skyrmions.Finally,the skyrmion charge number and diameter both decrease if the nonmagnetic defects exist,and the skyrmion centers are prone to being captured by defect sites.This work evidences that the ensembles of homochiral skyrmions stabilized in the multilayers fabricated by well-established technologies present a roadmap to design new classes of the materials that can host skyrmions.
基金supported by the National Key R&D Program China (Grant No.2022YFA1402802)the National Natural Science Foundation of China (Grant Nos.12374103 and 12074057)。
文摘Within the magnonics community,there has been a lot of interests in the magnon–skyrmion interaction.Magnons and skyrmions are two intriguing phenomena in condensed matter physics,and magnetic nanotubes have emerged as a suitable platform to study their complex interactions.We show that magnon frequency combs can be induced in magnetic nanotubes by three-wave mixing between the propagating magnons and skyrmion.This study enriches our fundamental comprehension of magnon–skyrmion interactions and holds promise for developing innovative spintronic devices and applications.This frequency comb tunability and unique spectral features offer a rich platform for exploring novel avenues in magnetic nanotechnology.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1402802)the National Natural Science Foundation of China(Grant Nos.12434003,12374103,and 12074057).
文摘We investigate the skyrmion motion driven by spin waves on magnetic nanotubes through micromagnetic simulations.Our key results include demonstrating the stability and enhanced mobility of skyrmions on the edgeless nanotube geometry,which prevents destruction at boundaries—a common issue in planar geometries.We explore the influence of the damping coefficient,amplitude,and frequency of microwaves on skyrmion dynamics,revealing a non-uniform velocity profile characterized by acceleration and deceleration phases.Our results show that the skyrmion Hall effect is significantly modulated on nanotubes compared to planar models,with specific dependencies on the spin-wave parameters.These findings provide insights into skyrmion manipulation for spintronic applications,highlighting the potential for high-speed and efficient information transport in magnonic devices.
基金Project supported in part by the National Natural Science Foundation of China(Grant No.61832007)the Natural Science Foundation of Shanxi Province,China(Grant Nos.2021JM-221 and 2018JM6075)the Natural Science Basic Research Plan in Shanxi Province of China(Grant No.2020JQ-470)。
文摘The magnetic skyrmion transport driven by pure voltage-induced strain gradient is proposed and studied via micromagnetic simulation.Through combining the skyrmion with multiferroic heterojunction,a voltage-induced uniaxial strain gradient is adjusted to move skyrmions.In the system,a pair of short-circuited trapezoidal top electrodes can generate the symmetric strain.Due to the symmetry of strain,the magnetic skyrmion can be driven with a linear motion in the middle of the nanostrip without deviation.We calculate the strain distribution generated by the trapezoidal top electrodes pair,and further investigate the influence of the strain intensity as well as the strain gradient on the skyrmion velocity.Our findings provide a stable and low-energy regulation method for skyrmion transport.
