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Gonçalves MAP, Paściak M, Hlinka J. Antiskyrmions in Ferroelectric Barium Titanate. PHYSICAL REVIEW LETTERS 2024; 133:066802. [PMID: 39178440 DOI: 10.1103/physrevlett.133.066802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 05/16/2024] [Accepted: 06/21/2024] [Indexed: 08/25/2024]
Abstract
Typical magnetic skyrmion is a string of inverted magnetization within a ferromagnet, protected by a sleeve of a vortexlike spin texture, such that its cross-section carries an integer topological charge. Some magnets form antiskyrmions, the antiparticle strings which carry an opposite topological charge. Here we demonstrate that topologically equivalent but purely electric antiskyrmion can exist in a ferroelectric material as well. In particular, our computer experiments reveal that the archetype ferroelectric, barium titanate, can host antiskyrmions at zero field. The polarization pattern around their cores reminds ring windings of decorative knots rather than the typical magnetic antiskyrmion texture. We show that the antiskyrmion of barium titanate has just 2-3 nm in diameter, a hexagonal cross section, and an exotic topological charge with doubled magnitude and opposite sign when compared to the standard skyrmion string.
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2
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Sun WJ, Zhou N, Chen WN, Sheng ZQ, Wu HW. Acoustic Skyrmionic Mode Coupling and Transferring in a Chain of Subwavelength Metastructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2401370. [PMID: 38981042 DOI: 10.1002/advs.202401370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/02/2024] [Indexed: 07/11/2024]
Abstract
Skyrmions, a stable topological vectorial textures characteristic with skyrmionic number, hold promise for advanced applications in information storage and transmission. While the dynamic motion control of skyrmions has been realized with various techniques in magnetics and optics, the manipulation of acoustic skyrmion has not been done. Here, the propagation and control of acoustic skyrmion along a chain of metastructures are shown. In coupled acoustic resonators made with Archimedes spiral channel, the skyrmion hybridization is found giving rise to bonding and antibonding skyrmionic modes. Furthermore, it is experimentally observed that the skyrmionic mode of acoustic velocity field distribution can be robustly transferred covering a long distance and almost no distortion of the skyrmion textures in a chain of metastructures, even if a structure defect is introduced in the travel path. The proposed localized acoustic skyrmionic mode coupling and propagating is expected in future applications for manipulating acoustic information storage and transfer.
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Affiliation(s)
- Wen-Jun Sun
- School of Mechanics and Photoelectric Physics, Anhui University of Science and Technology, Huainan, 232001, China
| | - Nong Zhou
- School of Mechanics and Photoelectric Physics, Anhui University of Science and Technology, Huainan, 232001, China
| | - Wan-Na Chen
- School of Mechanics and Photoelectric Physics, Anhui University of Science and Technology, Huainan, 232001, China
| | - Zong-Qiang Sheng
- School of Mechanics and Photoelectric Physics, Anhui University of Science and Technology, Huainan, 232001, China
| | - Hong-Wei Wu
- School of Mechanics and Photoelectric Physics, Anhui University of Science and Technology, Huainan, 232001, China
- Center for Fundamental Physics, Anhui University of Science and Technology, Huainan, 232001, China
- Institute of Energy, Hefei Comprehensive National Science Center (Anhui Energy Laboratory), Hefei, 230031, China
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3
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Song D, Wang W, Zhang S, Liu Y, Wang N, Zheng F, Tian M, Dunin-Borkowski RE, Zang J, Du H. Steady motion of 80-nm-size skyrmions in a 100-nm-wide track. Nat Commun 2024; 15:5614. [PMID: 38965221 PMCID: PMC11224351 DOI: 10.1038/s41467-024-49976-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 06/27/2024] [Indexed: 07/06/2024] Open
Abstract
The current-driven movement of magnetic skyrmions along a nanostripe is essential for the advancement and functionality of a new category of spintronic devices resembling racetracks. Despite extensive research into skyrmion dynamics, experimental verification of current-induced motion of ultra-small skyrmions within an ultrathin nanostripe is still pending. Here, we unveil the motion of individual 80 nm-size skyrmions in an FeGe track with an ultrathin width of 100 nm. The skyrmions can move steadily along the track over a broad range of current densities by using controlled pulse durations of as low as 2 ns. The potential landscape, arising from the magnetic edge twists in such a geometrically confined system, introduces skyrmion inertia and ensures efficient motion with a vanishing skyrmion Hall angle. Our results showcase the steady motion of skyrmions in an ultrathin track, offering a practical pathway for implementing skyrmion-based spintronic devices.
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Affiliation(s)
- Dongsheng Song
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China.
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China.
| | - Weiwei Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China
| | - Shuisen Zhang
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China
- University of Science and Technology of China, Hefei, 230026, China
| | - Yizhou Liu
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China
| | - Ning Wang
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China
| | - Fengshan Zheng
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
- Spin-X Institute, Center for Electron Microscopy, School of Physics and Optoelectronics State Key Laboratory of Luminescent Materials and Devices Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, 511442, P. R. China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui, 230026, China
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH, 03824, USA
- Materials Science Program, University of New Hampshire, Durham, NH, 03824, USA
| | - Haifeng Du
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China.
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, 230031, China.
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui, 230026, China.
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4
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Zhou Y, Li S, Liang X, Zhou Y. Topological Spin Textures: Basic Physics and Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2312935. [PMID: 38861696 DOI: 10.1002/adma.202312935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 05/24/2024] [Indexed: 06/13/2024]
Abstract
In the face of escalating modern data storage demands and the constraints of Moore's Law, exploring spintronic solutions, particularly the devices based on magnetic skyrmions, has emerged as a promising frontier in scientific research. Since the first experimental observation of skyrmions, topological spin textures have been extensively studied for their great potential as efficient information carriers in spintronic devices. However, significant challenges have emerged alongside this progress. This review aims to synthesize recent advances in skyrmion research while addressing the major issues encountered in the field. Additionally, current research on promising topological spin structures in addition to skyrmions is summarized. Beyond 2D structures, exploration also extends to 1D magnetic solitons and 3D spin textures. In addition, a diverse array of emerging magnetic materials is introduced, including antiferromagnets and 2D van der Waals magnets, broadening the scope of potential materials hosting topological spin textures. Through a systematic examination of magnetic principles, topological categorization, and the dynamics of spin textures, a comprehensive overview of experimental and theoretical advances in the research of topological magnetism is provided. Finally, both conventional and unconventional applications are summarized based on spin textures proposed thus far. This review provides an outlook on future development in applied spintronics.
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Affiliation(s)
- Yuqing Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Shuang Li
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Xue Liang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
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5
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Grebenchuk S, McKeever C, Grzeszczyk M, Chen Z, Šiškins M, McCray ARC, Li Y, Petford-Long AK, Phatak CM, Ruihuan D, Zheng L, Novoselov KS, Santos EJG, Koperski M. Topological Spin Textures in an Insulating van der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2311949. [PMID: 38306214 DOI: 10.1002/adma.202311949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/09/2024] [Indexed: 02/04/2024]
Abstract
Generation and control of topological spin textures constitutes one of the most exciting challenges of modern spintronics given their potential applications in information storage technologies. Of particular interest are magnetic insulators, which due to low damping, absence of Joule heating and reduced dissipation can provide energy-efficient spin-textures platform. Here, it is demonstrated that the interplay between sample thickness, external magnetic fields, and optical excitations can generate a prolific paramount of spin textures, and their coexistence in insulating CrBr3 van der Waals (vdW) ferromagnets. Using high-resolution magnetic force microscopy and large-scale micromagnetic simulation methods, the existence of a large region in T-B phase diagram is demonstrated where different stripe domains, skyrmion crystals, and magnetic domains exist and can be intrinsically selected or transformed to each-other via a phase-switch mechanism. Lorentz transmission electron microscopy unveils the mixed chirality of the magnetic textures that are of Bloch-type at given conditions but can be further manipulated into Néel-type or hybrid-type via thickness-engineering. The topological phase transformation between the different magnetic objects can be further inspected by standard photoluminescence optical probes resolved by circular polarization indicative of an existence of exciton-skyrmion coupling mechanism. The findings identify vdW magnetic insulators as a promising framework of materials for the manipulation and generation of highly ordered skyrmion lattices relevant for device integration at the atomic level.
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Affiliation(s)
- Sergey Grebenchuk
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Conor McKeever
- Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Magdalena Grzeszczyk
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - Zhaolong Chen
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - Makars Šiškins
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
| | - Arthur R C McCray
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Yue Li
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Charudatta M Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Duan Ruihuan
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Nanyang Technological University, Singapore, 639798, Singapore
| | - Liu Zheng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Elton J G Santos
- Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK
- Higgs Centre for Theoretical Physics, The University of Edinburgh, Edinburgh, EH9 3FD, UK
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Maciej Koperski
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
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6
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Zhang H, Shao YT, Chen X, Zhang B, Wang T, Meng F, Xu K, Meisenheimer P, Chen X, Huang X, Behera P, Husain S, Zhu T, Pan H, Jia Y, Settineri N, Giles-Donovan N, He Z, Scholl A, N'Diaye A, Shafer P, Raja A, Xu C, Martin LW, Crommie MF, Yao J, Qiu Z, Majumdar A, Bellaiche L, Muller DA, Birgeneau RJ, Ramesh R. Spin disorder control of topological spin texture. Nat Commun 2024; 15:3828. [PMID: 38714653 PMCID: PMC11076609 DOI: 10.1038/s41467-024-47715-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 04/10/2024] [Indexed: 05/10/2024] Open
Abstract
Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe3GaTe2, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights the influence of random spin control of non-trivial topological spin textures.
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Affiliation(s)
- Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Yu-Tsun Shao
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Physics, University of California, Berkeley, CA, 94720, USA.
- Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou, Guangdong, 510275, China.
| | - Binhua Zhang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China
- Shanghai Qi Zhi Institute, Shanghai, 200030, China
| | - Tianye Wang
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Fanhao Meng
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kun Xu
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Peter Meisenheimer
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Xianzhe Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Piush Behera
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Sajid Husain
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Tiancong Zhu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Hao Pan
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Yanli Jia
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Nick Settineri
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | | | - Zehao He
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Andreas Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Alpha N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Archana Raja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Changsong Xu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, 200433, China.
- Shanghai Qi Zhi Institute, Shanghai, 200030, China.
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
- Department of Chemistry, Rice University, Houston, TX, 77005, USA
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Rice Advanced Materials Institute, Rice University, Houston, TX, 77005, USA
| | - Michael F Crommie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ziqiang Qiu
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Arun Majumdar
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Robert J Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Physics, University of California, Berkeley, CA, 94720, USA.
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA.
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
- Rice Advanced Materials Institute, Rice University, Houston, TX, 77005, USA.
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7
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Gong B, Wang L, Wang S, Yu Z, Xiong L, Xiong R, Liu Q, Zhang Y. Optimizing skyrmionium movement and stability via stray magnetic fields in trilayer nanowire constructs. Phys Chem Chem Phys 2024; 26:4716-4723. [PMID: 38251958 DOI: 10.1039/d3cp05340g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Skyrmioniums, known for their unique transport and regulatory properties, are emerging as potential cornerstones for future data storage systems. However, the stability of skyrmionium movement faces considerable challenges due to the skyrmion Hall effect, which is induced by deformation. In response, our research introduces an innovative solution: we utilized micro-magnetic simulations to create a sandwiched trilayer nanowire structure augmented with a stray magnetic field. This combination effectively guides the skyrmionium within the ferromagnetic (FM) layer. Our empirical investigations reveal that the use of a stray magnetic field not only reduces the size of the skyrmionium but also amplifies its stability. This dual-effect proficiently mitigates the deformation of skyrmionium movement and boosts their thermal stability. We find these positive outcomes are most pronounced at a particular intensity of the stray magnetic field. Importantly, the required stray magnetic field can be generated using a heavy metal (HM1) layer of suitable thickness, rendering the practical application of this approach plausible in real-world experiments. Additionally, we analyze the functioning mechanism based on the Landau-Lifshitz-Gilbert (LLG) equation and energy variation. We also develop a deep spiking neural network (DSNN), which achieves a remarkable recognition accuracy of 97%. This achievement is realized through supervised learning via the spike timing dependent plasticity rule (STDP), considering the nanostructure as an artificial synapse device that corresponds to the electrical properties of the nanostructure. In conclusion, our study provides invaluable insights for the design of innovative information storage devices utilizing skyrmionium technology. By tackling the issues presented by the skyrmion Hall effect, we outline a feasible route for the practical application of this advanced technology. Our research, therefore, serves as a robust platform for continued investigations in this field.
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Affiliation(s)
- Bin Gong
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University, Xiamen 361005, P. R. China
| | - Luowen Wang
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Sunan Wang
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Ziyang Yu
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Lun Xiong
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Rui Xiong
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Qingbo Liu
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Yue Zhang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
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8
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Tai JSB, Hess AJ, Wu JS, Smalyukh II. Field-controlled dynamics of skyrmions and monopoles. SCIENCE ADVANCES 2024; 10:eadj9373. [PMID: 38277460 PMCID: PMC10816702 DOI: 10.1126/sciadv.adj9373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 12/26/2023] [Indexed: 01/28/2024]
Abstract
Magnetic monopoles, despite their ongoing experimental search as elementary particles, have inspired the discovery of analogous excitations in condensed matter systems. In chiral condensed matter systems, emergent monopoles are responsible for the onset of transitions between topologically distinct states and phases, such as in the case of transitions from helical and conical phase to A-phase comprising periodic arrays of skyrmions. By combining numerical modeling and optical characterizations, we describe how different geometrical configurations of skyrmions terminating at monopoles can be realized in liquid crystals and liquid crystal ferromagnets. We demonstrate how these complex structures can be effectively manipulated by external magnetic and electric fields. Furthermore, we discuss how our findings may hint at similar dynamics in other physical systems and their potential applications.
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Affiliation(s)
- Jung-Shen B. Tai
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Andrew J. Hess
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Jin-Sheng Wu
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Ivan I. Smalyukh
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
- Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO 80309, USA
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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9
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Liu C, Wang J, He W, Zhang C, Zhang S, Yuan S, Hou Z, Qin M, Xu Y, Gao X, Peng Y, Liu K, Qiu ZQ, Liu JM, Zhang X. Strain-Induced Reversible Motion of Skyrmions at Room Temperature. ACS NANO 2024; 18:761-769. [PMID: 38127497 DOI: 10.1021/acsnano.3c09090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Magnetic skyrmions are topologically protected swirling spin textures with great potential for future spintronic applications. The ability to induce skyrmion motion using mechanical strain not only stimulates the exploration of exotic physics but also affords the opportunity to develop energy-efficient spintronic devices. However, the experimental realization of strain-driven skyrmion motion remains a formidable challenge. Herein, we demonstrate that the inhomogeneous uniaxial compressive strain can induce the movement of isolated skyrmions from regions of high strain to regions of low strain at room temperature, which was directly observed using an in situ Lorentz transmission electron microscope with a specially designed nanoindentation holder. We discover that the uniaxial compressive strain can transform skyrmions into a single domain with in-plane magnetization, resulting in the coexistence of skyrmions with a single domain along the direction of the strain gradient. Through comprehensive micromagnetic simulations, we reveal that the repulsive interactions between skyrmions and the single domain serve as the driving force behind the skyrmion motion. The precise control of skyrmion motion through strain provides exciting opportunities for designing advanced spintronic devices that leverage the intricate interplay between strain and magnetism.
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Affiliation(s)
- Chen Liu
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Junlin Wang
- School of Integrated Circuits, Guangdong University of Technology, Guangzhou 510006, China
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K
| | - Wa He
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Chenhui Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Senfu Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Shuai Yuan
- School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, P. R. China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Minghui Qin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Yongbing Xu
- School of Integrated Circuits, Guangdong University of Technology, Guangzhou 510006, China
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Yong Peng
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, P. R. China
| | - Kai Liu
- Physics Department, Georgetown University, Washington, D.C. 20057, United States
| | - Zi Qiang Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Jun-Ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 211102, P. R. China
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
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10
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Tang J, Wu Y, Jiang J, Kong L, Liu W, Wang S, Tian M, Du H. Sewing skyrmion and antiskyrmion by quadrupole of Bloch points. Sci Bull (Beijing) 2023; 68:2919-2923. [PMID: 37949740 DOI: 10.1016/j.scib.2023.10.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/15/2023] [Accepted: 10/24/2023] [Indexed: 11/12/2023]
Affiliation(s)
- Jin Tang
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China; Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Jialiang Jiang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Lingyao Kong
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China
| | - Wei Liu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei 230601, China
| | - Mingliang Tian
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, China; Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
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11
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Lang M, Pathak SA, Holt SJR, Beg M, Fangohr H. Controlling stable Bloch points with electric currents. Sci Rep 2023; 13:18934. [PMID: 37919352 PMCID: PMC10622520 DOI: 10.1038/s41598-023-45111-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/16/2023] [Indexed: 11/04/2023] Open
Abstract
The Bloch point is a point singularity in the magnetisation configuration, where the magnetisation vanishes. It can exist as an equilibrium configuration and plays an important role in many magnetisation reversal processes. In the present work, we focus on manipulating Bloch points in a system that can host stable Bloch points-a two-layer FeGe nanostrip with opposite chirality of the two layers. We drive Bloch points using spin-transfer torques and find that Bloch points can move collectively without any Hall effect and report that Bloch points are repelled from the sample boundaries and each other. We study pinning of Bloch points at wedge-shaped constrictions (notches) in the nanostrip and demonstrate that arrays of Bloch points can be moved past a series of notches in a controlled manner by applying consecutive current pulses of different strength. Finally, we simulate a T-shaped geometry and demonstrate that a Bloch point can be moved along different paths by applying current between suitable strip ends.
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Affiliation(s)
- Martin Lang
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany.
| | - Swapneel Amit Pathak
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Samuel J R Holt
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Marijan Beg
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
- Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Hans Fangohr
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
- Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761, Hamburg, Germany
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12
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He Z, Du W, Dou K, Dai Y, Huang B, Ma Y. Ferroelectrically tunable magnetic skyrmions in two-dimensional multiferroics. MATERIALS HORIZONS 2023; 10:3450-3457. [PMID: 37345913 DOI: 10.1039/d3mh00572k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/23/2023]
Abstract
Magnetic skyrmions are topologically protected entities that are promising for information storage and processing. Currently, an essential challenge for future advances of skyrmionic devices lies in achieving effective control of skyrmion properties. Here, through first-principles and Monte-Carlo simulations, we report the identification of nontrivial topological magnetism in two-dimensional multiferroics of Co2NF2. Because of ferroelectricity, monolayer Co2NF2 exhibits a large Dzyaloshinskii-Moriya interaction. This together with exchange interaction can stabilize magnetic skyrmions with the size of sub-10 nm under a moderate magnetic field. Importantly, arising from the magnetoelectric coupling effect, the chirality of magnetic skyrmions is ferroelectrically tunable, producing the four-fold degenerate skyrmions. When interfacing with monolayer MoSe2, the creation and annihilation of magnetic skyrmions, as well as phase transition between skyrmion and skyrmion lattice, can be realized in a ferroelectrically controllable fashion. A dimensionless parameter κ' is further proposed as the criterion for stabilizing magnetic skyrmions in such multiferroic lattices. Our work greatly enriches the two-dimensional skyrmionics and multiferroics research.
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Affiliation(s)
- Zhonglin He
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
| | - Wenhui Du
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
| | - Kaiying Dou
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
| | - Yandong Ma
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China.
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13
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Okumura S, Kravchuk VP, Garst M. Instability of Magnetic Skyrmion Strings Induced by Longitudinal Spin Currents. PHYSICAL REVIEW LETTERS 2023; 131:066702. [PMID: 37625063 DOI: 10.1103/physrevlett.131.066702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 06/13/2023] [Accepted: 07/11/2023] [Indexed: 08/27/2023]
Abstract
It is well established that spin-transfer torques exerted by in-plane spin currents give rise to a motion of magnetic skyrmions resulting in a skyrmion Hall effect. In films of finite thickness or in three-dimensional bulk samples the skyrmions extend in the third direction forming a string. We demonstrate that a spin current flowing longitudinally along the skyrmion string instead induces a Goldstone spin wave instability. Our analytical results are confirmed by micromagnetic simulations of both a single string as well as string lattices, suggesting that the instability eventually breaks the strings. A longitudinal current is thus able to melt the skyrmion string lattice via a nonequilibrium phase transition. For films of finite thickness or in the presence of disorder a threshold current will be required, and we estimate the latter assuming weak collective pinning.
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Affiliation(s)
- Shun Okumura
- Department of Applied Physics, the University of Tokyo, Tokyo 113-8656, Japan
| | - Volodymyr P Kravchuk
- Institut für Theoretische Festkörperphysik, Karlsruher Institut für Technologie, D-76131 Karlsruhe, Germany
- Bogolyubov Institute for Theoretical Physics of National Academy of Sciences of Ukraine, 03143 Kyiv, Ukraine
| | - Markus Garst
- Institut für Theoretische Festkörperphysik, Karlsruher Institut für Technologie, D-76131 Karlsruhe, Germany
- Institute for Quantum Materials and Technology, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany
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14
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Magadeev EB, Vakhitov RM, Kanbekov RR. Two methods of forming flat magnetic structures in magnetic films with topological features. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:215801. [PMID: 36913732 DOI: 10.1088/1361-648x/acc3ea] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/13/2023] [Indexed: 06/18/2023]
Abstract
The paper investigates vortex-like structures observed in ferromagnetic films with strong uniaxial easy-plane anisotropy in the presence of topological features in them. Two approaches to the creation of such features are considered, namely, perforation of the sample and the inclusion of artificial defects in it, and a theorem on their equivalence is proved, according to which the structure of magnetic inhomogeneities arising in the film itself turns out to be the same for both approaches. In the second case, the properties of magnetic vortices formed on defects are also studied, and for cylindrical defects explicit analytical expressions for the energy and configuration of vortices are obtained, which are applicable in a wide range of values of material parameters.
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Affiliation(s)
- E B Magadeev
- Laboratory of Design of New Materials, Bashkir State University, 450076 Bashkortostan, Russia
| | - R M Vakhitov
- Laboratory of Design of New Materials, Bashkir State University, 450076 Bashkortostan, Russia
| | - R R Kanbekov
- Laboratory of Design of New Materials, Bashkir State University, 450076 Bashkortostan, Russia
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15
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Gong B, Wei C, Yang H, Yu Z, Wang L, Xiong L, Xiong R, Lu Z, Zhang Y, Liu Q. Control and regulation of skyrmionic topological charge in a novel synthetic antiferromagnetic nanostructure. NANOSCALE 2023; 15:5257-5264. [PMID: 36794971 DOI: 10.1039/d2nr06498g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Skyrmionium is a combination of a skyrmion with a topological charge (Q is +1 or -1), resulting in a magnetic configuration with a total topological charge of Q = 0. Skyrmionium has distinctive characteristics, including a slightly higher velocity, motion restricted to the middle of the track without the skyrmion Hall effect (SkHE), and absence of an acceleration phase. However, there is little stray field due to the zero net magnetization, the topological charge Q is zero due to the magnetic configuration, and detecting skyrmionium is still challenging. In the present work, we propose a novel nanostructure composed of triple nanowires with a narrow channel. It was found that the skyrmionium is converted into a DW pair or skyrmion by the concave channel. It was also found that the topological charge Q can be regulated by Ruderman-Kittel-Kasuya-Yosida (RKKY) antiferromagnetic (AFM) exchange coupling. Moreover, we analyzed the mechanism of the function based on the Landau-Lifshitz-Gilbert (LLG) equation and energy variation and constructed a deep spiking neural network (DSNN) with a recognition accuracy of 98.6% with supervised learning via the spike timing dependent plasticity rule (STDP) by considering the nanostructure as an artificial synapse device corresponding to the electrical properties of the nanostructure. These results provide the means for skyrmion-skyrmionium hybrid application and neuromorphic computing applications.
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Affiliation(s)
- Bin Gong
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Chenhuinan Wei
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China
| | - Han Yang
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Ziyang Yu
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Luowen Wang
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Lun Xiong
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
| | - Rui Xiong
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Zhihong Lu
- The State Key Laboratory of Refractories and Metallurgy, School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Yue Zhang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Qingbo Liu
- Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China.
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16
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Kim SK, Tchernyshyov O. Mechanics of a ferromagnetic domain wall. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:134002. [PMID: 36693283 DOI: 10.1088/1361-648x/acb5d8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 01/24/2023] [Indexed: 06/17/2023]
Abstract
This paper gives a pedagogical introduction to the mechanics of ferromagnetic solitons. We start with the dynamics of a single spin and develop all the tools required for the description of the dynamics of solitons in a ferromagnet.
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Affiliation(s)
- Se Kwon Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Oleg Tchernyshyov
- William H Miller III Department of Physics and Astronomy and Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218, United States of America
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17
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Liu Y, Watanabe H, Nagaosa N. Emergent Magnetomultipoles and Nonlinear Responses of a Magnetic Hopfion. PHYSICAL REVIEW LETTERS 2022; 129:267201. [PMID: 36608193 DOI: 10.1103/physrevlett.129.267201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/13/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
The three-dimensional emergent magnetic field B^{e} of a magnetic hopfion gives rise to emergent magnetomultipoles in a similar manner to the multipoles of classical electromagnetic field. Here, we show that the nonlinear responses of a hopfion are characterized by its emergent magnetic toroidal moment T_{z}^{e}=1/2∫(r×B^{e})_{z}dV and emergent magnetic octupole component Γ^{e}=∫[(x^{2}+y^{2})B_{z}^{e}-xzB_{x}^{e}-yzB_{y}^{e}]dV. The hopfion exhibits nonreciprocal dynamics (nonlinear hopfion Hall effect) under an ac driving current applied along (perpendicular to) the direction of T_{z}^{e}. The sign of nonreciprocity and nonlinear Hall angle is determined by the polarity and chirality of hopfion. The nonlinear electrical transport induced by a magnetic hopfion is also discussed. This Letter reveals the vital roles of emergent magnetomultipoles in nonlinear hopfion dynamics and could stimulate further investigations on the dynamical responses of topological spin textures induced by emergent electromagnetic multipoles.
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Affiliation(s)
- Yizhou Liu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Hikaru Watanabe
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Naoto Nagaosa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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18
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Bellizotti Souza JC, Vizarim NP, Reichhardt CJO, Reichhardt C, Venegas PA. Magnus induced diode effect for skyrmions in channels with periodic potentials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 51:015804. [PMID: 36272354 DOI: 10.1088/1361-648x/ac9cc5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Using a particle based model, we investigate the skyrmion dynamical behavior in a channel where the upper wall contains divots of one depth and the lower wall contains divots of a different depth. Under an applied driving force, skyrmions in the channels move with a finite skyrmion Hall angle that deflects them toward the upper wall for -xdirection driving and the lower wall for +xdirection driving. When the upper divots have zero height, the skyrmions are deflected against the flat upper wall for -xdirection driving and the skyrmion velocity depends linearly on the drive. For +xdirection driving, the skyrmions are pushed against the lower divots and become trapped, giving reduced velocities and a nonlinear velocity-force response. When there are shallow divots on the upper wall and deep divots on the lower wall, skyrmions get trapped for both driving directions; however, due to the divot depth difference, skyrmions move more easily under -xdirection driving, and become strongly trapped for +xdirection driving. The preferred -xdirection motion produces what we call a Magnus diode effect since it vanishes in the limit of zero Magnus force, unlike the diode effects observed for asymmetric sawtooth potentials. We show that the transport curves can exhibit a series of jumps or dips, negative differential conductivity, and reentrant pinning due to collective trapping events. We also discuss how our results relate to recent continuum modeling on a similar skyrmion diode system.
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Affiliation(s)
- J C Bellizotti Souza
- Departamento de Física, Faculdade de Ciências, Unesp-Universidade Estadual Paulista, CP 473, 17033-360 Bauru, SP, Brazil
| | - N P Vizarim
- POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Faculdade de Ciências, Universidade Estadual Paulista-UNESP, CP 473, 17033-360 Bauru, SP, Brazil
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - P A Venegas
- Departamento de Física, Faculdade de Ciências, Unesp-Universidade Estadual Paulista, CP 473, 17033-360 Bauru, SP, Brazil
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19
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Eto R, Pohle R, Mochizuki M. Low-Energy Excitations of Skyrmion Crystals in a Centrosymmetric Kondo-Lattice Magnet: Decoupled Spin-Charge Excitations and Nonreciprocity. PHYSICAL REVIEW LETTERS 2022; 129:017201. [PMID: 35841562 DOI: 10.1103/physrevlett.129.017201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/25/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
We theoretically study spin and charge excitations of skyrmion crystals stabilized by conduction-electron-mediated magnetic interactions via spin-charge coupling in a centrosymmetric Kondo-lattice model by large-scale spin-dynamics simulations combined with the kernel polynomial method. We reveal clear segregation of spin and charge excitation channels and nonreciprocal nature of the spin excitations governed by the Fermi-surface geometry, which are unique to the skyrmion crystals in centrosymmetric itinerant hosts and can be a source of novel physical phenomena.
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Affiliation(s)
- Rintaro Eto
- Department of Applied Physics, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Rico Pohle
- Department of Applied Physics, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
- Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Masahito Mochizuki
- Department of Applied Physics, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
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20
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Zhang H, Raftrey D, Chan YT, Shao YT, Chen R, Chen X, Huang X, Reichanadter JT, Dong K, Susarla S, Caretta L, Chen Z, Yao J, Fischer P, Neaton JB, Wu W, Muller DA, Birgeneau RJ, Ramesh R. Room-temperature skyrmion lattice in a layered magnet (Fe 0.5Co 0.5) 5GeTe 2. SCIENCE ADVANCES 2022; 8:eabm7103. [PMID: 35319983 PMCID: PMC8942374 DOI: 10.1126/sciadv.abm7103] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 01/28/2022] [Indexed: 05/26/2023]
Abstract
Novel magnetic ground states have been stabilized in two-dimensional (2D) magnets such as skyrmions, with the potential next-generation information technology. Here, we report the experimental observation of a Néel-type skyrmion lattice at room temperature in a single-phase, layered 2D magnet, specifically a 50% Co-doped Fe5GeTe2 (FCGT) system. The thickness-dependent magnetic domain size follows Kittel's law. The static spin textures and spin dynamics in FCGT nanoflakes were studied by Lorentz electron microscopy, variable-temperature magnetic force microscopy, micromagnetic simulations, and magnetotransport measurements. Current-induced skyrmion lattice motion was observed at room temperature, with a threshold current density, jth = 1 × 106 A/cm2. This discovery of a skyrmion lattice at room temperature in a noncentrosymmetric material opens the way for layered device applications and provides an ideal platform for studies of topological and quantum effects in 2D.
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Affiliation(s)
- Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - David Raftrey
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Physics Department, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Ying-Ting Chan
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Rui Chen
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - Jonathan T. Reichanadter
- Department of Electrical Engineering, University of California, Berkeley, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Kaichen Dong
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sandhya Susarla
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
| | - Zhen Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Physics Department, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Jeffrey B. Neaton
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
- Kavli Energy Nanosciences Institute at Berkeley, Berkeley, CA, USA
| | - Weida Wu
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - David A. Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Robert J. Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA
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21
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Abstract
Writing, erasing and computing are three fundamental operations required by any working electronic device. Magnetic skyrmions could be essential bits in promising in emerging topological spintronic devices. In particular, skyrmions in chiral magnets have outstanding properties like compact texture, uniform size, and high mobility. However, creating, deleting, and driving isolated skyrmions, as prototypes of aforementioned basic operations, have been a grand challenge in chiral magnets ever since the discovery of skyrmions, and achieving all these three operations in a single device is even more challenging. Here, by engineering chiral magnet Co8Zn10Mn2 into the customized micro-devices for in-situ Lorentz transmission electron microscopy observations, we implement these three operations of skyrmions using nanosecond current pulses with a low current density of about 1010 A·m−2 at room temperature. A notched structure can create or delete magnetic skyrmions depending on the direction and magnitude of current pulses. We further show that the magnetic skyrmions can be deterministically shifted step-by-step by current pulses, allowing the establishment of the universal current-velocity relationship. These experimental results have immediate significance towards the skyrmion-based memory or logic devices. There has been much interest in using skyrmions for new approaches to compution, however, creating, deleting and driving skyrmions remains a challenge. Here, Wang et al demonstrate all three operations for skyrmions in tailored Co8Zn10Mn2 nanodevices using tailored current pulses.
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22
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Behavior of Vortex-Like Inhomogeneities Originating in Magnetic Films with Modulated Uniaxial Anisotropy in a Planar Magnetic Field. Symmetry (Basel) 2022. [DOI: 10.3390/sym14030612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This paper investigates the processes of magnetization reversal of a uniaxial ferromagnetic disk containing a columnar defect of the potential well type in perpendicular and planar magnetic fields. The characteristic stages of magnetization reversal of the domain structure of the disk and vortex-like inhomogeneities forming on the defect are determined. The critical fields of their existence are found and an explanation is given for the presence of a significant difference in their values for the perpendicular and planar fields of the defect magnetization reversal. The role of chirality in the behavior of a Bloch-type magnetic skyrmion during the magnetization reversal of a defect in a planar field is shown.
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23
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Hou Z, Wang Y, Lan X, Li S, Wan X, Meng F, Hu Y, Fan Z, Feng C, Qin M, Zeng M, Zhang X, Liu X, Fu X, Yu G, Zhou G, Zhou Y, Zhao W, Gao X, Liu JM. Controlled Switching of the Number of Skyrmions in a Magnetic Nanodot by Electric Fields. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107908. [PMID: 34969153 DOI: 10.1002/adma.202107908] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Magnetic skyrmions are topological swirling spin configurations that hold promise for building future magnetic memories and logic circuits. Skyrmionic devices typically rely on the electrical manipulation of a single skyrmion, but controllably manipulating a group of skyrmions can lead to more compact and memory-efficient devices. Here, an electric-field-driven cascading transition of skyrmion clusters in a nanostructured ferromagnetic/ferroelectric multiferroic heterostructure is reported, which allows a continuous multilevel transition of the number of skyrmions in a one-by-one manner. Most notably, the transition is non-volatile and reversible, which is crucial for multi-bit memory applications. Combined experiments and theoretical simulations reveal that the switching of skyrmion clusters is induced by the strain-mediated modification of both the interfacial Dzyaloshinskii-Moriya interaction and effective uniaxial anisotropy. The results not only open up a new direction for constructing low-power-consuming, non-volatile, and multi-bit skyrmionic devices, but also offer valuable insights into the fundamental physics underlying the voltage manipulation of skyrmion clusters.
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Affiliation(s)
- Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yadong Wang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Xiaoming Lan
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Sai Li
- Fert Beijing Institute, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xuejin Wan
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Fei Meng
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yangfan Hu
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan, 523808, P. R. China
| | - Zhen Fan
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Chun Feng
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Minghui Qin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Min Zeng
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Xuewen Fu
- Ultrafast Electron Microscopy Laboratory, School of Physics, Nankai University, Tianjin, 300071, P. R. China
| | - Guanghua Yu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, P. R. China
| | - Weisheng Zhao
- Fert Beijing Institute, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Jun-Ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 211102, P. R. China
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24
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Wolf D, Schneider S, Rößler UK, Kovács A, Schmidt M, Dunin-Borkowski RE, Büchner B, Rellinghaus B, Lubk A. Unveiling the three-dimensional magnetic texture of skyrmion tubes. NATURE NANOTECHNOLOGY 2022; 17:250-255. [PMID: 34931032 PMCID: PMC8930765 DOI: 10.1038/s41565-021-01031-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 10/12/2021] [Indexed: 05/04/2023]
Abstract
Magnetic skyrmions are stable topological solitons with complex non-coplanar spin structures. Their nanoscopic size and the low electric currents required to control their motion has opened a new field of research, skyrmionics, that aims for the usage of skyrmions as information carriers. Further advances in skyrmionics call for a thorough understanding of their three-dimensional (3D) spin texture, skyrmion-skyrmion interactions and the coupling to surfaces and interfaces, which crucially affect skyrmion stability and mobility. Here, we quantitatively reconstruct the 3D magnetic texture of Bloch skyrmions with sub-10-nanometre resolution using holographic vector-field electron tomography. The reconstructed textures reveal local deviations from a homogeneous Bloch character within the skyrmion tubes, details of the collapse of the skyrmion texture at surfaces and a correlated modulation of the skyrmion tubes in FeGe along their tube axes. Additionally, we confirm the fundamental principles of skyrmion formation through an evaluation of the 3D magnetic energy density across these magnetic solitons.
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Affiliation(s)
- Daniel Wolf
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
| | - Sebastian Schneider
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
- Dresden Center for Nanoanalysis, cfaed, Technische Universität Dresden, Dresden, Germany
| | - Ulrich K Rößler
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany
| | - Marcus Schmidt
- Department Chemical Metal Science, Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany
| | - Bernd Büchner
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
- Institute of Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Bernd Rellinghaus
- Dresden Center for Nanoanalysis, cfaed, Technische Universität Dresden, Dresden, Germany
| | - Axel Lubk
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany.
- Institute of Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany.
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany.
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25
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Intrinsic topological magnons in arrays of magnetic dipoles. Sci Rep 2022; 12:1420. [PMID: 35082356 PMCID: PMC8792029 DOI: 10.1038/s41598-022-05469-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/12/2022] [Indexed: 11/09/2022] Open
Abstract
We study a simple magnetic system composed of periodically modulated magnetic dipoles with an easy axis. Upon adjusting the geometric modulation amplitude alone, chains and two-dimensional stacked chains exhibit a rich magnon spectrum where frequency gaps and magnon speeds are easily manipulable. The blend of anisotropy due to dipolar interactions between magnets and geometrical modulation induces a magnetic phase with fractional Zak number in infinite chains and end states in open one-dimensional systems. In two dimensions it gives rise to topological modes at the edges of stripes. Tuning the amplitude in two-dimensional lattices causes a band touching, which triggers the exchange of the Chern numbers of the volume bands and switches the sign of the thermal conductivity.
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26
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Tang J, Wu Y, Wang W, Kong L, Lv B, Wei W, Zang J, Tian M, Du H. Magnetic skyrmion bundles and their current-driven dynamics. NATURE NANOTECHNOLOGY 2021; 16:1086-1091. [PMID: 34341518 DOI: 10.1038/s41565-021-00954-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
Topological charge Q classifies non-trivial spin textures and determines many of their characteristics. Most abundant are topological textures with |Q| ≤ 1, such as (anti)skyrmions, (anti)merons or (anti)vortices. In this study we created and imaged in real space magnetic skyrmion bundles, that is, multi-Q three-dimensional skyrmionic textures. These textures consist of a circular spin spiral that ties together a discrete number of skyrmion tubes. We observed skyrmion bundles with integer Q values up to 55. We show here that electric currents drive the collective motion of these particle-like textures similar to skyrmions. Bundles with Q ≠ 0 exhibit a skyrmion Hall effect with a Hall angle of ~62°, whereas Q = 0 bundles, the so-called skyrmioniums, propagate collinearly with respect to the current flow, that is, with a skyrmion Hall angle of ~0°. The experimental observation of multi-Q spin textures adds another member to the family of magnetic topological textures, which may serve in future spintronic devices.
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Affiliation(s)
- Jin Tang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China
- Key Laboratory for Photoelectric Detection Science and Technology of Education Department of Anhui Province, School of Physics and Materials Engineering, Hefei Normal University, Hefei, China
| | - Weiwei Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, China
| | - Lingyao Kong
- School of Physics and Materials Science, Anhui University, Hefei, China
| | - Boyao Lv
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China
| | - Wensen Wei
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA
- Materials Science Program, University of New Hampshire, Durham, NH, USA
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China
- School of Physics and Materials Science, Anhui University, Hefei, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, China.
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, China.
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27
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Wei W, Tang J, Wu Y, Wang Y, Jiang J, Li J, Soh Y, Xiong Y, Tian M, Du H. Current-Controlled Topological Magnetic Transformations in a Nanostructured Kagome Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101610. [PMID: 34224181 DOI: 10.1002/adma.202101610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/14/2021] [Indexed: 06/13/2023]
Abstract
Topological magnetic charge Q is a fundamental parameter that describes the magnetic domains and determines their intriguing electromagnetic properties. The ability to switch Q in a controlled way by electrical methods allows for flexible manipulation of electromagnetic behavior in future spintronic devices. Here, the room-temperature current-controlled topological magnetic transformations between Q = -1 skyrmions and Q = 0 stripes or type-II bubbles in a kagome crystal Fe3 Sn2 are reported. It is shown that reproducible and reversible skyrmion-bubble and skyrmion-stripe transformations can be achieved by tuning the density of nanosecond pulsed current of the order of ≈1010 A m-2 . Further numerical simulations suggest that spin-transfer torque combined with Joule thermal heating effects determine the current-induced topological magnetic transformations.
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Affiliation(s)
- Wensen Wei
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jin Tang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Key Laboratory for Photoelectric Detection Science and Technology of Education Department of Anhui Province, and School of Physics and Materials Engineering, Hefei Normal University, Hefei, 230601, China
| | - Yihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jialiang Jiang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Junbo Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yona Soh
- Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- School of Physics and Materials Science, Anhui University, Hefei, 230601, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
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28
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Mak KY, Xia J, Zhang X, Ezawa M, Liu X, Zhou Y. Transcription and logic operations of magnetic skyrmions in bilayer cross structures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:404001. [PMID: 34229301 DOI: 10.1088/1361-648x/ac117e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
Magnetic skyrmions are potential building blocks for future information storage and computing devices. Here, we computationally study the skyrmion dynamics in a cross structure made of two ferromagnetic nanotracks. We show that by controlling the skyrmion motion in the cross structure using spin currents, it is possible to realize the transcription of skyrmion at the intersection of the cross structure at certain conditions. Based on the transcription of skyrmion, we computationally demonstrate the AND, OR and NOT logical gates using the cross structures with modified geometries and appropriate magnetic parameters. Our results may provide guidelines to design future three-dimensional spintronics devices based on magnetic skyrmions.
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Affiliation(s)
- Kai Yu Mak
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, People's Republic of China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, People's Republic of China
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Motohiko Ezawa
- Department of Applied Physics, University of Tokyo, Hongo 7-3-1, Tokyo 113-8656, Japan
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, People's Republic of China
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29
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Teixeira AW, Castillo-Sepúlveda S, Rizzi LG, Nunez AS, Troncoso RE, Altbir D, Fonseca JM, Carvalho-Santos VL. Motion-induced inertial effects and topological phase transitions in skyrmion transport. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:265403. [PMID: 33902016 DOI: 10.1088/1361-648x/abfb8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
When the skyrmion dynamics beyond the particle-like description is considered, this topological structure can deform due to a self-induced field. In this work, we perform Monte Carlo simulations to characterize the skyrmion deformation during its steady movement. In the low-velocity regime, the deformation in the skyrmion shape is quantified by an effective inertial mass, which is related to the dissipative force. When skyrmions move faster, the large self-induced deformation triggers topological transitions. These transitions are characterized by the proliferation of skyrmions and a different total topological charge, which is obtained as a function of the skyrmion velocity. Our findings provide an alternative way to describe the dynamics of a skyrmion that accounts for the deformations of its structure. Furthermore, such motion-induced topological phase transitions make it possible to control the number of ferromagnetic skyrmions through velocity effects.
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Affiliation(s)
- A W Teixeira
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - S Castillo-Sepúlveda
- Facultad de Ingeniería, Universidad Autónoma de Chile, Av. Pedro de Valdivia 425, Providencia, Santiago, Chile
| | - L G Rizzi
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - A S Nunez
- Departamento de Física, FCFM, CEDENNA, Universidad de Chile, Santiago, Chile
| | - R E Troncoso
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - D Altbir
- Departamento de Física, CEDENNA, Universidad de Santiago de Chile, USACH, Santiago, Chile
| | - J M Fonseca
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - V L Carvalho-Santos
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
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30
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Skyrmion crystals in centrosymmetric itinerant magnets without horizontal mirror plane. Sci Rep 2021; 11:11184. [PMID: 34045497 PMCID: PMC8160153 DOI: 10.1038/s41598-021-90308-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 05/10/2021] [Indexed: 11/09/2022] Open
Abstract
We theoretically investigate a new stabilization mechanism of a skyrmion crystal (SkX) in centrosymmetric itinerant magnets with magnetic anisotropy. By considering a trigonal crystal system without the horizontal mirror plane, we derive an effective spin model with an anisotropic Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction for a multi-band periodic Anderson model. We find that the anisotropic RKKY interaction gives rise to two distinct SkXs with different skyrmion numbers of one and two depending on a magnetic field. We also clarify that a phase arising from the multiple-Q spin density waves becomes a control parameter for a field-induced topological phase transition between the SkXs. The mechanism will be useful not only for understanding the SkXs, such as that in Gd[Formula: see text]PdSi[Formula: see text], but also for exploring further skyrmion-hosting materials in trigonal itinerant magnets.
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31
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Ohara K, Zhang X, Chen Y, Wei Z, Ma Y, Xia J, Zhou Y, Liu X. Confinement and Protection of Skyrmions by Patterns of Modified Magnetic Properties. NANO LETTERS 2021; 21:4320-4326. [PMID: 33950694 DOI: 10.1021/acs.nanolett.1c00865] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Magnetic skyrmions are versatile topological excitations that can be used as nonvolatile information carriers. The confinement of skyrmions in channels is fundamental for any application based on the accumulation and transport of skyrmions. Here, we report a method that allows effective position control of skyrmions in designed channels by engineered energy barriers and wells, which is realized in a magnetic multilayer film by harnessing the boundaries of patterns with modified magnetic properties. We experimentally and computationally demonstrate that skyrmions can be attracted or repelled by the boundaries of areas with modified perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction. By fabricating square and stripe patterns with modified magnetic properties, we show the possibility of building reliable channels for confinement, accumulation, and transport of skyrmions, which effectively protect skyrmions from being destroyed at the device edges. Our results are useful for the design of spintronic applications using either static or dynamic skyrmions.
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Affiliation(s)
- Kentaro Ohara
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Yinling Chen
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Zonhan Wei
- School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001, China
| | - Yungui Ma
- State Key Lab of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
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32
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Deriving the skyrmion Hall angle from skyrmion lattice dynamics. Nat Commun 2021; 12:2723. [PMID: 33976177 PMCID: PMC8113591 DOI: 10.1038/s41467-021-22857-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 03/30/2021] [Indexed: 11/08/2022] Open
Abstract
Magnetic skyrmions are topologically non-trivial, swirling magnetization textures that form lattices in helimagnetic materials. These magnetic nanoparticles show promise as high efficiency next-generation information carriers, with dynamics that are governed by their topology. Among the many unusual properties of skyrmions is the tendency of their direction of motion to deviate from that of a driving force; the angle by which they diverge is a materials constant, known as the skyrmion Hall angle. In magnetic multilayer systems, where skyrmions often appear individually, not arranging themselves in a lattice, this deflection angle can be easily measured by tracing the real space motion of individual skyrmions. Here we describe a reciprocal space technique which can be used to determine the skyrmion Hall angle in the skyrmion lattice state, leveraging the properties of the skyrmion lattice under a shear drive. We demonstrate this procedure to yield a quantitative measurement of the skyrmion Hall angle in the room-temperature skyrmion system FeGe, shearing the skyrmion lattice with the magnetic field gradient generated by a single turn Oersted wire. Skyrmions, when driven by any applied force, experience an addition sideways motion known as the skyrmion hall effect. Here, Brearton et al. present a reciprocal space method for determining the strength of the skyrmion hall effect, making measurement possible for skyrmion lattices.
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33
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Abstract
Skyrmion, a concept originally proposed in particle physics half a century ago, can now find the most fertile field for its applicability, that is, the magnetic skyrmion realized in helimagnetic materials. The spin swirling vortex-like texture of the magnetic skyrmion can define the particle nature by topology; that is, all the constituent spin moments within the two-dimensional sheet wrap the sphere just one time. Such a topological nature of the magnetic skyrmion can lead to extraordinary metastability via topological protection and the driven motion with low electric-current excitation, which may promise future application to spintronics. The skyrmions in the magnetic materials frequently show up as the crystal lattice form, e.g., hexagonal lattice, but sometimes as isolated or independent particles. These skyrmions in magnets were initially found in acentric magnets, such as chiral, polar, and bilayered magnets endowed with antisymmetric spin exchange interaction, while the skyrmion host materials have been explored in a broader family of compounds including centrosymmetric magnets. This review describes the materials science and materials chemistry of magnetic skyrmions using the classification scheme of the skyrmion forming microscopic mechanisms. The emergent phenomena and functions mediated by skyrmions are described, including the generation of emergent magnetic and electric field by statics and dynamics of skrymions and the inherent magnetoelectric effect. The other important magnetic topological defects in two or three dimensions, such as biskyrmions, antiskyrmions, merons, and hedgehogs, are also reviewed in light of their interplay with the skyrmions.
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Affiliation(s)
- Yoshinori Tokura
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.,RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.,Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Göbel B, Mertig I. Skyrmion ratchet propagation: utilizing the skyrmion Hall effect in AC racetrack storage devices. Sci Rep 2021; 11:3020. [PMID: 33542288 PMCID: PMC7862652 DOI: 10.1038/s41598-021-81992-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/14/2021] [Indexed: 11/23/2022] Open
Abstract
Magnetic skyrmions are whirl-like nano-objects with topological protection. When driven by direct currents, skyrmions move but experience a transverse deflection. This so-called skyrmion Hall effect is often regarded a drawback for memory applications. Herein, we show that this unique effect can also be favorable for spintronic applications: We show that in a racetrack with a broken inversion symmetry, the skyrmion Hall effect allows to translate an alternating current into a directed motion along the track, like in a ratchet. We analyze several modes of the ratchet mechanism and show that it is unique for topological magnetic whirls. We elaborate on the fundamental differences compared to the motion of topologically trivial magnetic objects, as well as classical particles driven by periodic forces. Depending on the exact racetrack geometry, the ratchet mechanism can be soft or strict. In the latter case, the skyrmion propagates close to the efficiency maximum.
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Affiliation(s)
- Börge Göbel
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.
| | - Ingrid Mertig
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany
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35
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Chen S, Yuan S, Hou Z, Tang Y, Zhang J, Wang T, Li K, Zhao W, Liu X, Chen L, Martin LW, Chen Z. Recent Progress on Topological Structures in Ferroic Thin Films and Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2000857. [PMID: 32815214 DOI: 10.1002/adma.202000857] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/17/2020] [Indexed: 06/11/2023]
Abstract
Topological spin/polarization structures in ferroic materials continue to draw great attention as a result of their fascinating physical behaviors and promising applications in the field of high-density nonvolatile memories as well as future energy-efficient nanoelectronic and spintronic devices. Such developments have been made, in part, based on recent advances in theoretical calculations, the synthesis of high-quality thin films, and the characterization of their emergent phenomena and exotic phases. Herein, progress over the last decade in the study of topological structures in ferroic thin films and heterostructures is explored, including the observation of topological structures and control of their structures and emergent physical phenomena through epitaxial strain, layer thickness, electric, magnetic fields, etc. First, the evolution of topological spin structures (e.g., magnetic skyrmions) and associated functionalities (e.g., topological Hall effect) in magnetic thin films and heterostructures is discussed. Then, the exotic polar topologies (e.g., domain walls, closure domains, polar vortices, bubble domains, and polar skyrmions) and their emergent physical properties in ferroelectric oxide films and heterostructures are explored. Finally, a brief overview and prospectus of how the field may evolve in the coming years is provided.
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Affiliation(s)
- Shanquan Chen
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Shuai Yuan
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yunlong Tang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
| | - Jinping Zhang
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Tao Wang
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Kang Li
- Flexible Printed Electronics Technology Center, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Weiwei Zhao
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
- Flexible Printed Electronics Technology Center, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Xingjun Liu
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
| | - Lang Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Zuhuang Chen
- School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China
- Flexible Printed Electronics Technology Center, Harbin Institute of Technology, Shenzhen, 518055, China
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Wang W, Zhao YF, Wang F, Daniels MW, Chang CZ, Zang J, Xiao D, Wu W. Chiral-Bubble-Induced Topological Hall Effect in Ferromagnetic Topological Insulator Heterostructures. NANO LETTERS 2021; 21:1108-1114. [PMID: 33404255 PMCID: PMC8276525 DOI: 10.1021/acs.nanolett.0c04567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report compelling evidence of an emergent topological Hall effect (THE) from chiral bubbles in a two-dimensional uniaxial ferromagnet, V-doped Sb2Te3 heterostructure. The sign of THE signal is determined by the net curvature of domain walls in different domain configurations, and the strength of THE signal is correlated with the density of nucleation or pinned bubble domains. The experimental results are in good agreement with the integrated linear transport and Monte Carlo simulations, corroborating the emergent gauge field at chiral magnetic bubbles. Our findings not only reveal a general mechanism of THE in two-dimensional ferromagnets but also pave the way for the creation and manipulation of topological spin textures for spintronic applications.
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Affiliation(s)
- Wenbo Wang
- Department of Physics, University of California, Santa Barbara, CA 93106, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Corresponding author:
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Fei Wang
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Matthew W. Daniels
- Alternative Computing Group, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jiadong Zang
- Department of Physics and Materials Science Program, University of New Hampshire, Durham, NH 03824, USA
| | - Di Xiao
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Weida Wu
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Corresponding author:
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Lim ZS, Li C, Huang Z, Chi X, Zhou J, Zeng S, Omar GJ, Feng YP, Rusydi A, Pennycook SJ, Venkatesan T, Ariando A. Emergent Topological Hall Effect at a Charge-Transfer Interface. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2004683. [PMID: 33191619 DOI: 10.1002/smll.202004683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 10/25/2020] [Indexed: 06/11/2023]
Abstract
Exploring exotic interface magnetism due to charge transfer and strong spin-orbit coupling has profound application in the future development of spintronic memory. Here, the emergence and tuning of topological Hall effect (THE) from a CaMnO3 /CaIrO3 /CaMnO3 trilayer structure are studied in detail, which suggests the presence of magnetic Skyrmion-like bubbles. First, by tilting the magnetic field direction, the evolution of the Hall signal suggests a transformation of Skyrmions into topologically-trivial stripe domains, consistent with behaviors predicted by micromagnetic simulations. Second, by varying the thickness of CaMnO3 , the optimal thicknesses for the THE signal emergence are found, which allow identification of the source of Dzyaloshinskii-Moriya interaction (DMI) and its competition with antiferromagnetic superexchange. Employing high-resolution transmission electron microscopy, randomly distributed stacking faults are identified only at the bottom interface and may avoid mutual cancellation of DMI. Last, a spin-transfer torque experiment also reveals a low threshold current density of ≈109 A m-2 for initiating the bubbles' motion. This discovery sheds light on a possible strategy for integrating Skyrmions with antiferromagnetic spintronics.
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Affiliation(s)
- Zhi Shiuh Lim
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Changjian Li
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhen Huang
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiao Chi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Jun Zhou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Shengwei Zeng
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Ganesh Ji Omar
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Andrivo Rusydi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Stephen John Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Ariando Ariando
- NUSNNI-NanoCore, National University of Singapore, Singapore, 117411, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
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Controlling bimerons as skyrmion analogues by ferroelectric polarization in 2D van der Waals multiferroic heterostructures. Nat Commun 2020; 11:5930. [PMID: 33230183 PMCID: PMC7683542 DOI: 10.1038/s41467-020-19779-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 10/30/2020] [Indexed: 11/08/2022] Open
Abstract
Atom-thick van der Waals heterostructures with nontrivial physical properties tunable via the magnetoelectric coupling effect are highly desirable for the future advance of multiferroic devices. In this work on LaCl/In2Se3 heterostructure consisting of a 2D ferromagnetic layer and a 2D ferroelectric layer, reversible switch of the easy axis and the Curie temperature of the magnetic LaCl layer has been enabled by switching of ferroelectric polarization in In2Se3. More importantly, magnetic skyrmions in the bimerons form have been discovered in the LaCl/In2Se3 heterostructure and can be driven by an electric current. The creation and annihilation of bimerons in LaCl magnetic nanodisks were achieved by polarization switching. It thus proves to be a feasible approach to achieve purely electric control of skyrmions in 2D van der Waals heterostructures. Such nonvolatile and tunable magnetic skyrmions are promising candidates for information carriers in future data storage and logic devices operated under small electrical currents.
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Bulk and surface topological indices for a skyrmion string: current-driven dynamics of skyrmion string in stepped samples. Sci Rep 2020; 10:20303. [PMID: 33219262 PMCID: PMC7680146 DOI: 10.1038/s41598-020-76469-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 10/28/2020] [Indexed: 11/21/2022] Open
Abstract
The magnetic skyrmion is a topological magnetic vortex, and its topological nature is characterized by an index called skyrmion number which is a mapping of the magnetic moments defined on a two-dimensional space to a unit sphere. In three-dimensions, a skyrmion, i.e., a vortex penetrating though the magnet naturally forms a string, which terminates at the surfaces of the magnet or in the bulk. For such a string, the topological indices, which control its topological stability are less trivial. Here, we study theoretically, in terms of numerical simulation, the dynamics of current-driven motion of a skyrmion string in a film sample with the step edges on the surface. In particular, skyrmion–antiskyrmion pair is generated by driving a skyrmion string through the side step with an enough height. We find that the topological indices relevant to the stability are the followings; (1) skyrmion number along the developed surface, and (2) the monopole charge in the bulk defined as the integral over the surface enclosing a singular magnetic configuration. As long as the magnetic configuration is slowly varying, the former is conserved while its changes is associated with nonzero monopole charge. The skyrmion number and the monoplole charge offer a coherent understanding of the stability of the topological magnetic texture and the nontrivial dynamics of skyrmion strings.
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40
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Rózsa L, Weißenhofer M, Nowak U. Spin waves in skyrmionic structures with various topological charges. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:054001. [PMID: 33091880 DOI: 10.1088/1361-648x/abc404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/22/2020] [Indexed: 06/11/2023]
Abstract
Equilibrium properties and localized magnon excitations are investigated in topologically distinct skyrmionic textures. The observed shape of the structures and their orientation on the lattice is explained based on their vorticities and the symmetry of the crystal. The transformation between different textures and their annihilation as a function of magnetic field is understood based on the energy differences between them. The angular momentum spin-wave eigenmodes characteristic of cylindrically symmetric structures are combined in the distorted spin configurations, leading to avoided crossings in the magnon spectrum. The susceptibility of the skyrmionic textures to homogeneous external fields is calculated, revealing that a high number of modes become detectable due to the hybridization between the angular momentum eigenmodes. These findings should contribute to the observation of spin waves in distorted skyrmionic structures via experiments and numerical simulations, widening the range of their possible applications in magnonic devices.
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Affiliation(s)
- Levente Rózsa
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Markus Weißenhofer
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Ulrich Nowak
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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41
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Guang Y, Peng Y, Yan Z, Liu Y, Zhang J, Zeng X, Zhang S, Zhang S, Burn DM, Jaouen N, Wei J, Xu H, Feng J, Fang C, van der Laan G, Hesjedal T, Cui B, Zhang X, Yu G, Han X. Electron Beam Lithography of Magnetic Skyrmions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003003. [PMID: 32812294 DOI: 10.1002/adma.202003003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/27/2020] [Indexed: 05/08/2023]
Abstract
The emergence of magnetic skyrmions, topological spin textures, has aroused tremendous interest in studying the rich physics related to their topology. While skyrmions promise high-density and energy-efficient magnetic memory devices for information technology, the manifestation of their nontrivial topology through single skyrmions and ordered and disordered skyrmion lattices could also give rise to many fascinating physical phenomena, such as chiral magnon and skyrmion glass states. Therefore, generating skyrmions at designated locations on a large scale, while controlling the skyrmion patterns, is the key to advancing topological magnetism. Here, a new, yet general, approach to the "printing" of skyrmions with zero-field stability in arbitrary patterns on a massive scale in exchange-biased magnetic multilayers is presented. By exploiting the fact that the antiferromagnetic order can be reconfigured by local thermal excitations, a focused electron beam with a graphic pattern generator to "print" skyrmions is used, which is referred to as skyrmion lithography. This work provides a route to design arbitrary skyrmion patterns, thereby establishing the foundation for further exploration of topological magnetism.
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Affiliation(s)
- Yao Guang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yong Peng
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Zhengren Yan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yizhou Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Junwei Zhang
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, 730000, China
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xue Zeng
- School of Mathematics and Physics, Lanzhou Jiaotong University, Lanzhou, 730070, China
| | - Senfu Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Shilei Zhang
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - David M Burn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Nicolas Jaouen
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, Gif-sur-Yvette, 91192, France
| | - Jinwu Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Hongjun Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jiafeng Feng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chi Fang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Gerrit van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Thorsten Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Baoshan Cui
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Xixiang Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
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Wang Y, Wang L, Xia J, Lai Z, Tian G, Zhang X, Hou Z, Gao X, Mi W, Feng C, Zeng M, Zhou G, Yu G, Wu G, Zhou Y, Wang W, Zhang XX, Liu J. Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure. Nat Commun 2020; 11:3577. [PMID: 32681004 PMCID: PMC7367868 DOI: 10.1038/s41467-020-17354-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 06/26/2020] [Indexed: 11/09/2022] Open
Abstract
Electrical manipulation of skyrmions attracts considerable attention for its rich physics and promising applications. To date, such a manipulation is realized mainly via spin-polarized current based on spin-transfer torque or spin-orbital torque effect. However, this scheme is energy consuming and may produce massive Joule heating. To reduce energy dissipation and risk of heightened temperatures of skyrmion-based devices, an effective solution is to use electric field instead of current as stimulus. Here, we realize an electric-field manipulation of skyrmions in a nanostructured ferromagnetic/ferroelectrical heterostructure at room temperature via an inverse magneto-mechanical effect. Intriguingly, such a manipulation is non-volatile and exhibits a multistate feature. Numerical simulations indicate that the electric-field manipulation of skyrmions originates from strain-mediated modification of effective magnetic anisotropy and Dzyaloshinskii-Moriya interaction. Our results open a direction for constructing low-energy-dissipation, non-volatile, and multistate skyrmion-based spintronic devices.
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Affiliation(s)
- Yadong Wang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Lei Wang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Zhengxun Lai
- Colleage of Science, Tianjin University, Tianjin, 300392, China
| | - Guo Tian
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Xichao Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China.
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China.
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China.
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China.
| | - Wenbo Mi
- Colleage of Science, Tianjin University, Tianjin, 300392, China
| | - Chun Feng
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Min Zeng
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Guanghua Yu
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Guangheng Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Wenhong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xi-Xiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Junming Liu
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 211102, China
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43
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Zhao L, Wang Z, Zhang X, Liang X, Xia J, Wu K, Zhou HA, Dong Y, Yu G, Wang KL, Liu X, Zhou Y, Jiang W. Topology-Dependent Brownian Gyromotion of a Single Skyrmion. PHYSICAL REVIEW LETTERS 2020; 125:027206. [PMID: 32701308 DOI: 10.1103/physrevlett.125.027206] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/02/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
Noninteracting particles exhibiting Brownian motion have been observed in many occasions of sciences, such as molecules suspended in liquids, optically trapped microbeads, and spin textures in magnetic materials. In particular, a detailed examination of Brownian motion of spin textures is important for designing thermally stable spintronic devices, which motivates the present study. In this Letter, through using temporally and spatially resolved polar magneto-optic Kerr effect microscopy, we have experimentally observed the thermal fluctuation-induced random walk of a single isolated Néel-type magnetic skyrmion in an interfacially asymmetric Ta/CoFeB/TaO_{x} multilayer. An intriguing topology-dependent Brownian gyromotion behavior of skyrmions has been identified. The onset of Brownian gyromotion of a single skyrmion induced by thermal effects, including a nonlinear temperature-dependent diffusion coefficient and topology-dependent gyromotion are further formulated based on the stochastic Thiele equation. The experimental and numerical demonstration of topology-dependent Brownian gyromotion of skyrmions can be useful for understanding the nonequilibrium magnetization dynamics and implementing spintronic devices.
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Affiliation(s)
- Le Zhao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Zidong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Xichao Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Xue Liang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Keyu Wu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Heng-An Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Yiqing Dong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Wanjun Jiang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
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44
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Budhathoki S, Sapkota A, Law KM, Ranjit S, Nepal B, Hoskins BD, Thind AS, Borisevich AY, Jamer ME, Anderson TJ, Koehler AD, Hobart KD, Stephen GM, Heiman D, Mewes T, Mishra R, Gallagher JC, Hauser AJ. Room Temperature Skyrmions in Strain-Engineered FeGe thin films. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.220405. [PMID: 38487734 PMCID: PMC10938551 DOI: 10.1103/physrevb.101.220405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
Skyrmions hold great promise for low-energy consumption and stable high density information storage, and stabilization of the skyrmion lattice (SkX) phase at or above room temperature is greatly desired for practical use. The topological Hall effect can be used to identify candidate systems above room temperature, a challenging regime for direct observation by Lorentz electron microscopy. Atomically ordered FeGe thin films are grown epitaxially on Ge(111) substrates with ~ 4 % tensile strain. Magnetic characterization reveals enhancement of Curie temperature to 350 K due to strain, well above the bulk value of 278 K. Strong topological Hall effect was observed between 10 K and 330 K, with a significant increase in magnitude observed at 330 K. The increase in magnitude occurs just below the Curie temperature, a similar relative temperature position as the onset of Skx phase in bulk FeGe. The results suggest that strained FeGe films may host a SkX phase above room temperature when significant tensile strain is applied.
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Affiliation(s)
- Sujan Budhathoki
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Arjun Sapkota
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Ka Ming Law
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Smriti Ranjit
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Bhuwan Nepal
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Brian D Hoskins
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A
| | - Arashdeep Singh Thind
- Institute of Materials Science Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
| | - Albina Y Borisevich
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A
| | - Michelle E Jamer
- Physics Department, United States Naval Academy, Annapolis, MD 21402, U.S.A
| | | | | | - Karl D Hobart
- Naval Research Laboratory, Washington, DC 20375, U.S.A
| | - Gregory M Stephen
- Physics Department, Northeastern University, Boston, MA 02115, U.S.A
| | - Don Heiman
- Physics Department, Northeastern University, Boston, MA 02115, U.S.A
| | - Tim Mewes
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Rohan Mishra
- Institute of Materials Science Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
- Department of Mechanical Engineering Materials Science, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
| | | | - Adam J Hauser
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
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Zhang X, Zhou Y, Mee Song K, Park TE, Xia J, Ezawa M, Liu X, Zhao W, Zhao G, Woo S. Skyrmion-electronics: writing, deleting, reading and processing magnetic skyrmions toward spintronic applications. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:143001. [PMID: 31689688 DOI: 10.1088/1361-648x/ab5488] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The field of magnetic skyrmions has been actively investigated across a wide range of topics during the last decades. In this topical review, we mainly review and discuss key results and findings in skyrmion research since the first experimental observation of magnetic skyrmions in 2009. We particularly focus on the theoretical, computational and experimental findings and advances that are directly relevant to the spintronic applications based on magnetic skyrmions, i.e. their writing, deleting, reading and processing driven by magnetic field, electric current and thermal energy. We then review several potential applications including information storage, logic computing gates and non-conventional devices such as neuromorphic computing devices. Finally, we discuss possible future research directions on magnetic skyrmions, which also cover rich topics on other topological textures such as antiskyrmions and bimerons in antiferromagnets and frustrated magnets.
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Affiliation(s)
- Xichao Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, People's Republic of China
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46
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Bai C, Chen J, Zhang Y, Zhang D, Zhan Q. Dynamic tailoring of an optical skyrmion lattice in surface plasmon polaritons. OPTICS EXPRESS 2020; 28:10320-10328. [PMID: 32225619 DOI: 10.1364/oe.384718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/11/2020] [Indexed: 06/10/2023]
Abstract
A skyrmion is a topologically protected soliton with a spin structure on the micro/nano scale that has promising applications in magnetic information storage and spintronics devices. This study focuses on the optical skyrmion lattice structures created in the surface plasmon polaritons (SPPs) field. Both the Néel-type optical skyrmion lattice formed by the electric field vector and Bloch-type optical skyrmion lattice formed by the magnetic field vector are generated via exciting a hexagonal grating structure on the metal surface with six Gaussian optical spots. Such a multiple-spot excitation can be realized through tightly focusing a specially designed complex field with a high NA lens. Through introducing the phase difference of the excitation beams to shift the SPP standing waves, the shape and position of the optical skyrmion lattice can be dynamically controlled. Both the electric field vector and magnetic field vector are evaluated quantitatively based on the electric and magnetic field obtained by finite difference time domain (FDTD) simulation to demonstrate the validity and capability of the proposed technique.
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47
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Liu Y, Hou W, Han X, Zang J. Three-Dimensional Dynamics of a Magnetic Hopfion Driven by Spin Transfer Torque. PHYSICAL REVIEW LETTERS 2020; 124:127204. [PMID: 32281873 DOI: 10.1103/physrevlett.124.127204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/05/2020] [Indexed: 06/11/2023]
Abstract
Magnetic hopfion is a three-dimensional (3D) topological soliton with novel spin structure that would enable exotic dynamics. Here, we study the current-driven 3D dynamics of a magnetic hopfion with a unit Hopf index in a frustrated magnet. Attributed to the spin Berry phase and symmetry of the hopfion, the phase space entangles multiple collective coordinates, thus the hopfion exhibits rich dynamics including longitudinal motion along the current direction, transverse motion perpendicular to the current direction, rotational motion, and dilation. Furthermore, the characteristics of hopfion dynamics is determined by the ratio between the nonadiabatic spin transfer torque parameter and the damping parameter. Such peculiar 3D dynamics of magnetic hopfion could shed light on understanding the universal physics of hopfions in different systems and boost the prosperous development of 3D spintronics.
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Affiliation(s)
- Yizhou Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wentao Hou
- Department of Physics and Astronomy, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, New Hampshire 03824, USA
- Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824, USA
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48
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Malik IA, Huang H, Wang Y, Wang X, Xiao C, Sun Y, Ullah R, Zhang Y, Wang J, Malik MA, Ahmed I, Xiong C, Finizio S, Kläui M, Gao P, Wang J, Zhang J. Inhomogeneous-strain-induced magnetic vortex cluster in one-dimensional manganite wire. Sci Bull (Beijing) 2020; 65:201-207. [PMID: 36659173 DOI: 10.1016/j.scib.2019.11.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/23/2019] [Accepted: 11/12/2019] [Indexed: 01/21/2023]
Abstract
Mixed-valance manganites with strong electron correlation exhibit strong potential for spintronics, where emergent magnetic behaviors, such as propagation of high-frequency spin waves and giant topological Hall Effects can be driven by their mesoscale spin textures. Here, we create magnetic vortex clusters with flux closure spin configurations in single-crystal La0.67Sr0.33MnO3 wire. A distinctive transformation from out-of-plane domains to a vortex state is directly visualized using magnetic force microscopy at 4 K in wires when the width is below 1.0 μm. The phase-field modeling indicates that the inhomogeneous strain, accompanying with shape anisotropy, plays a key role for stabilizing the flux-closure spin structure. This work offers a new perspective for understanding and manipulating the non-trivial spin textures in strongly correlated systems.
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Affiliation(s)
| | - Houbing Huang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Yu Wang
- Department of Engineering Mechanics & Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou 310027, China
| | - Xueyun Wang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Cui Xiao
- Department of Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Yuanwei Sun
- International Center for Quantum Materials and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Rizwan Ullah
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Yuelin Zhang
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Jing Wang
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | | | - Irfan Ahmed
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Changmin Xiong
- Department of Physics, Beijing Normal University, Beijing 100875, China.
| | - Simone Finizio
- Department of Physics, Johannes Gutenberg-University Mainz, Mainz 55099, Germany; Graduate School of Excellence Materials Science in Mainz, Mainz 55128, Germany
| | - Mathias Kläui
- Department of Physics, Johannes Gutenberg-University Mainz, Mainz 55099, Germany; Graduate School of Excellence Materials Science in Mainz, Mainz 55128, Germany
| | - Peng Gao
- International Center for Quantum Materials and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jie Wang
- Department of Engineering Mechanics & Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
| | - Jinxing Zhang
- Department of Physics, Beijing Normal University, Beijing 100875, China.
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49
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Mochizuki M. Dynamical magnetoelectric phenomena of skyrmions in multiferroics. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2019-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Magnetic skyrmions, nanoscopic spin vortices carrying a quantized topological number in chiral-lattice magnets, are recently attracting great research interest. Although magnetic skyrmions had been observed only in metallic chiral-lattice magnets such as B20 alloys in the early stage of the research, their realization was discovered in 2012 also in an insulating chiral-lattice magnet
Cu
2
OSeO
3
$\textrm{Cu}_2\textrm{OSeO}_3$
. A characteristic of the insulating skyrmions is that they can host multiferroicity, that is, the noncollinear magnetization alignment of skyrmion induces electric polarizations in insulators with a help of the relativistic spin-orbit interaction. It was experimentally confirmed that the skyrmion phase in
Cu
2
OSeO
3
$\textrm{Cu}_2\textrm{OSeO}_3$
is indeed accompanied by the spin-induced ferroelectricity. The resulting strong magnetoelectric coupling between magnetizations and electric polarizations can provide us with a means to manipulate and activate magnetic skyrmions by application of electric fields. This is in sharp contrast to skyrmions in metallic systems, which are driven through injection of electric currents. The magnetoelectric phenomena specific to the skyrmion-based multiferroics are attracting intensive research interest, and, in particular, those in dynamical regime are widely recognized as an issue of vital importance because their understanding is crucial both for fundamental science and for technical applications. In this article, we review recent studies on multiferroic properties and dynamical magnetoelectric phenomena of magnetic skyrmions in insulating chiral-lattice magnet
Cu
2
OSeO
3
$\textrm{Cu}_2\textrm{OSeO}_3$
. It is argued that the multiferroic skyrmions show unique resonant excitation modes of coupled magnetizations and polarizations, so-called electromagnon excitations, which can be activated both magnetically with a microwave magnetic field and electrically with a microwave electric field. The interference between these two activation processes gives rise to peculiar phenomena in the gigahertz regime. As its representative example, we discuss a recent theoretical prediction of unprecedentedly large nonreciprocal directional dichroism of microwaves in the skyrmion phase of
Cu
2
OSeO
3
$\textrm{Cu}_2\textrm{OSeO}_3$
. This phenomenon can be regarded as a one-way window effect on microwaves, that is, the extent of microwave absorption changes significantly when its incident direction is reversed. This dramatic effect was indeed observed by subsequent experiments. These studies demonstrated that the multiferroic skyrmions can be a promising building block for microwave devices.
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Affiliation(s)
- Masahito Mochizuki
- Department of Applied Physics , Waseda University , 3-4-1 Okubo, Shinjuku-ku , Tokyo , 169-8050 , Japan
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50
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Diameter-independent skyrmion Hall angle observed in chiral magnetic multilayers. Nat Commun 2020; 11:428. [PMID: 31969569 PMCID: PMC6976618 DOI: 10.1038/s41467-019-14232-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/13/2019] [Indexed: 11/24/2022] Open
Abstract
Magnetic skyrmions are topologically non-trivial nanoscale objects. Their topology, which originates in their chiral domain wall winding, governs their unique response to a motion-inducing force. When subjected to an electrical current, the chiral winding of the spin texture leads to a deflection of the skyrmion trajectory, characterised by an angle with respect to the applied force direction. This skyrmion Hall angle is predicted to be skyrmion diameter-dependent. In contrast, our experimental study finds that the skyrmion Hall angle is diameter-independent for skyrmions with diameters ranging from 35 to 825 nm. At an average velocity of 6 ± 1 ms−1, the average skyrmion Hall angle was measured to be 9° ± 2°. In fact, the skyrmion dynamics is dominated by the local energy landscape such as materials defects and the local magnetic configuration. Magnetic skyrmions are promising objects for future spintronic devices. However, a better understanding of their dynamics is required. Here, the authors show that in contrast to predictions the skyrmion Hall angle is independent of their diameter and motion is dominated by disorder and skyrmion-skyrmion interactions in the system.
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