The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic si...The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.展开更多
The aggregation of topological spin textures at nano and micro scales has prac-tical applications in spintronic technologies.Here,the authors report the in-plane current-induced proliferation and aggregation of bimero...The aggregation of topological spin textures at nano and micro scales has prac-tical applications in spintronic technologies.Here,the authors report the in-plane current-induced proliferation and aggregation of bimerons in a bulk chiral magnet.It is found that the spin-transfer torques can induce the proliferation and aggrega-tion of bimerons only in the presence of an appropriate out-of-plane magneticfield.It is also found that a relatively small damping and a relatively large non-adiabatic spin-transfer torque could lead to more pronounced bimeron proliferation and aggre-gation.Particularly,the current density should be larger than a certain threshold in order to trigger the proliferation;namely,the bimerons may only be driven into translational motion under weak current injection.Besides,the authorsfind that the aggregate bimerons could relax into a deformed honeycomb bimeron lattice with a few lattice structure defects after the current injection.The results are promising for the development of bio-inspired spintronic devices that use a large number of aggregate bimerons.Thefindings also provide a platform for studying aggregation-induced effects in spintronic systems,such as the aggregation-induced lattice phase transitions.展开更多
Optical skyrmions,as quasiparticles with non-trivial topological structures,have garnered significant attention in recent years.This paper proposes a method for customized spin angular momentum(SAM)distribution in hig...Optical skyrmions,as quasiparticles with non-trivial topological structures,have garnered significant attention in recent years.This paper proposes a method for customized spin angular momentum(SAM)distribution in highly localized focal fields,thereby enabling the generation of SAM skyrmion and bimeron topologies.The skyrmionic SAM textures can be flexibly controlled,such as polarity,vorticity,and helicity.In addition,the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space.By utilizing time-reversal techniques,we obtain the required illumination fields of the 4π-focusing system and subsequently evaluate the tightly focused field using vector Debye integral theory.Our results show that the SAM orientation within the focal field is controlled by the orientation of orthogonal dipole pairs.Using the radiation field of a multi-concentric array of orthogonal dipole pairs,the distribution of SAM orientation in the target plane can be tailored to generate SAM topological structures such as skyrmions and bimerons.Highly localized and tunable SAM engineering holds great potential for applications in optical manipulation,light–matter interactions,optical information processing,transmission,and storage.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 12174382)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB0460000 and XDB28000000)the Innovation Program for Quantum Science and Technology (Grant Nos. 2024ZD0300104 and 2021ZD0302600)。
文摘The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.
基金Waseda University,Grant/Award Number:2024C-153Shenzhen Peacock Group Plan,Grant/Award Number:KQTD20180413181702403+4 种基金National Natural Science Foundation of China,Grant/Award Number:12374123Shenzhen Fundamental Research Program,Grant/Award Number:JCYJ20210324120213037Basic and Applied Basic Research Foundation of Guangdong Province,Grant/Award Number:2021B1515120047Japan Science and Technology Agency,Grant/Award Number:JPMJCR20T1Japan Society for the Promotion of Science,Grant/Award Numbers:JP20H00337,JP23H04522,JP24H02231。
文摘The aggregation of topological spin textures at nano and micro scales has prac-tical applications in spintronic technologies.Here,the authors report the in-plane current-induced proliferation and aggregation of bimerons in a bulk chiral magnet.It is found that the spin-transfer torques can induce the proliferation and aggrega-tion of bimerons only in the presence of an appropriate out-of-plane magneticfield.It is also found that a relatively small damping and a relatively large non-adiabatic spin-transfer torque could lead to more pronounced bimeron proliferation and aggre-gation.Particularly,the current density should be larger than a certain threshold in order to trigger the proliferation;namely,the bimerons may only be driven into translational motion under weak current injection.Besides,the authorsfind that the aggregate bimerons could relax into a deformed honeycomb bimeron lattice with a few lattice structure defects after the current injection.The results are promising for the development of bio-inspired spintronic devices that use a large number of aggregate bimerons.Thefindings also provide a platform for studying aggregation-induced effects in spintronic systems,such as the aggregation-induced lattice phase transitions.
基金National Natural Science Foundation of China(12434012,92050202,12274299)Natural Science Foundation of Fujian Province(2024J01789,2022J011102)+1 种基金Science and Technology Commission of Shanghai Municipality(22QA1406600)Quanzhou City Science and Technology Program(2024QZGZ7)。
文摘Optical skyrmions,as quasiparticles with non-trivial topological structures,have garnered significant attention in recent years.This paper proposes a method for customized spin angular momentum(SAM)distribution in highly localized focal fields,thereby enabling the generation of SAM skyrmion and bimeron topologies.The skyrmionic SAM textures can be flexibly controlled,such as polarity,vorticity,and helicity.In addition,the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space.By utilizing time-reversal techniques,we obtain the required illumination fields of the 4π-focusing system and subsequently evaluate the tightly focused field using vector Debye integral theory.Our results show that the SAM orientation within the focal field is controlled by the orientation of orthogonal dipole pairs.Using the radiation field of a multi-concentric array of orthogonal dipole pairs,the distribution of SAM orientation in the target plane can be tailored to generate SAM topological structures such as skyrmions and bimerons.Highly localized and tunable SAM engineering holds great potential for applications in optical manipulation,light–matter interactions,optical information processing,transmission,and storage.
