1
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Garanin DA, Soriano JF, Chudnovsky EM. Melting and freezing of a skyrmion lattice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:475802. [PMID: 39142350 DOI: 10.1088/1361-648x/ad6f8b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Accepted: 08/14/2024] [Indexed: 08/16/2024]
Abstract
We report comprehensive Monte-Carlo studies of the melting of skyrmion lattices (SkL) in systems of small, medium, and large sizes with the number of skyrmions ranging from 103to over 105. Large systems exhibit hysteresis similar to that observed in real experiments on the melting of SkLs. For sufficiently small systems which achieve thermal equilibrium, a fully reversible sharp solid-liquid transition on temperature with no intermediate hexatic phase is observed. A similar behavior is found on changing the magnetic field that provides the control of pressure in the SkL. We find that on heating the melting transition occurs via a formation of grains with different orientations of hexagonal axes. On cooling, the fluctuating grains coalesce into larger clusters until a uniform orientation of hexagonal axes is slowly established. The observed scenario is caused by collective effects involving defects and is more complex than a simple picture of a transition driven by the unbinding and annihilation of dislocation and disclination pairs.
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Affiliation(s)
- Dmitry A Garanin
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589, United States of America
| | - Jorge F Soriano
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589, United States of America
| | - Eugene M Chudnovsky
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589, United States of America
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2
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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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3
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Pan XF, Li PB, Hei XL, Zhang X, Mochizuki M, Li FL, Nori F. Magnon-Skyrmion Hybrid Quantum Systems: Tailoring Interactions via Magnons. PHYSICAL REVIEW LETTERS 2024; 132:193601. [PMID: 38804949 DOI: 10.1103/physrevlett.132.193601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 01/08/2024] [Accepted: 04/08/2024] [Indexed: 05/29/2024]
Abstract
Coherent and dissipative interactions between different quantum systems are essential for the construction of hybrid quantum systems and the investigation of novel quantum phenomena. Here, we propose and analyze a magnon-skyrmion hybrid quantum system, consisting of a micromagnet and nearby magnetic skyrmions. We predict a strong-coupling mechanism between the magnonic mode of the micromagnet and the quantized helicity degree of freedom of the skyrmion. We show that with this hybrid setup it is possible to induce magnon-mediated nonreciprocal interactions and responses between distant skyrmion qubits or between skyrmion qubits and other quantum systems like superconducting qubits. This work provides a quantum platform for the investigation of diverse quantum effects and quantum information processing with magnetic microstructures.
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Affiliation(s)
- Xue-Feng Pan
- Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Peng-Bo Li
- Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xin-Lei Hei
- Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xichao Zhang
- Department of Applied Physics, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Masahito Mochizuki
- Department of Applied Physics, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Fu-Li Li
- Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Center for Quantum Computing, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
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4
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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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5
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Roy P, Zhang D, Mazza AR, Cucciniello N, Kunwar S, Zeng H, Chen A, Jia Q. Manipulating topological Hall-like signatures by interface engineering in epitaxial ruthenate/manganite heterostructures. NANOSCALE 2023; 15:17589-17598. [PMID: 37873761 DOI: 10.1039/d3nr02407e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Topologically protected non-trivial spin textures (e.g. skyrmions) give rise to a novel phenomenon called the topological Hall effect (THE) and have promising implications in future energy-efficient nanoelectronic and spintronic devices. Here, we have studied the Hall effect in SrRuO3/La0.42Ca0.58MnO3 (SRO/LCMO) bilayers. Our investigation suggests that pure SRO has hard and soft magnetic characteristics but the anomalous Hall effect (AHE) in SRO is governed by the high coercivity phase. We have shown that the proximity effect of a soft magnetic LCMO on SRO plays a critical role in interfacial magnetic coupling and transport properties in SRO. Upon reducing the SRO thickness in the bilayer, the proximity effect becomes the dominant feature, enhancing the magnitude and temperature range of THE-like signatures. The THE-like features in bilayers can be explained by a diffusive Berry phase transition model in the presence of an emergent magnetic state due to interface coupling. This work provides an alternative understanding of THE-like signatures and their manipulation in SRO-based heterostructures, bilayers and superlattices.
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Affiliation(s)
- Pinku Roy
- Department of Materials Design and Innovation, University at Buffalo - The State University of New York, Buffalo, NY 14260, USA.
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Di Zhang
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Alessandro R Mazza
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Nicholas Cucciniello
- Department of Materials Design and Innovation, University at Buffalo - The State University of New York, Buffalo, NY 14260, USA.
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Sundar Kunwar
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Hao Zeng
- Department of Physics, University at Buffalo - The State University of New York, Buffalo, NY 14260, USA
| | - Aiping Chen
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Quanxi Jia
- Department of Materials Design and Innovation, University at Buffalo - The State University of New York, Buffalo, NY 14260, USA.
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Liu C, Jiang J, Zhang C, Wang Q, Zhang H, Zheng D, Li Y, Ma Y, Algaidi H, Gao X, Hou Z, Mi W, Liu J, Qiu Z, Zhang X. Controllable Skyrmionic Phase Transition between Néel Skyrmions and Bloch Skyrmionic Bubbles in van der Waals Ferromagnet Fe 3-δ GeTe 2. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303443. [PMID: 37505392 PMCID: PMC10520623 DOI: 10.1002/advs.202303443] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/05/2023] [Indexed: 07/29/2023]
Abstract
The van der Waals (vdW) ferromagnet Fe3-δ GeTe2 has garnered significant research interest as a platform for skyrmionic spin configurations, that is, skyrmions and skyrmionic bubbles. However, despite extensive efforts, the origin of the Dzyaloshinskii-Moriya interaction (DMI) in Fe3-δ GeTe2 remains elusive, making it challenging to acquire these skyrmionic phases in a controlled manner. In this study, it is demonstrated that the Fe content in Fe3-δ GeTe2 has a profound effect on the crystal structure, DMI, and skyrmionic phase. For the first time, a marked increase in Fe atom displacement with decreasing Fe content is observed, transforming the original centrosymmetric crystal structure into a non-centrosymmetric symmetry, leading to a considerable DMI. Additionally, by varying the Fe content and sample thickness, a controllable transition between Néel-type skyrmions and Bloch-type skyrmionic bubbles is achieved, governed by a delicate interplay between dipole-dipole interaction and the DMI. The findings offer novel insights into the variable skyrmionic phases in Fe3-δ GeTe2 and provide the impetus for developing vdW ferromagnet-based spintronic devices.
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Affiliation(s)
- Chen Liu
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Jiawei Jiang
- Tianjin Key Laboratory of Low‐Dimensional Materials Physics and Preparation Technology, School of ScienceTianjin UniversityTianjin300354China
| | - Chenhui Zhang
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Qingping Wang
- College of Electronic Information and AutomationAba Teachers UniversityPixian StreetSichuan623002China
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Huai Zhang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Dongxing Zheng
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Yan Li
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Yinchang Ma
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Hanin Algaidi
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
| | - Wenbo Mi
- Tianjin Key Laboratory of Low‐Dimensional Materials Physics and Preparation Technology, School of ScienceTianjin UniversityTianjin300354China
| | - Jun‐ming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing211102China
| | - Ziqiang Qiu
- Department of PhysicsUniversity of California at BerkeleyBerkeleyCA94720USA
| | - Xixiang Zhang
- Physical Science and Engineering Division (PSE)King Abdullah University of Science and Technology (KAUST)Thuwal23955‐6900Saudi Arabia
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7
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Li B, Zhang H, Tao Q, Shen X, Huang Z, He K, Yi C, Li X, Zhang L, Zhang Z, Liu J, Tang J, Zhou Y, Wang D, Yang X, Zhao B, Wu R, Li J, Li B, Duan X. Thickness-Dependent Topological Hall Effect in 2D Cr 5 Si 3 Nanosheets with Noncollinear Magnetic Phase. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210755. [PMID: 36719342 DOI: 10.1002/adma.202210755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/05/2023] [Indexed: 06/18/2023]
Abstract
Antiferromagnets with noncollinear spin order are expected to exhibit unconventional electromagnetic response, such as spin Hall effects, chiral abnormal, quantum Hall effect, and topological Hall effect. Here, 2D thickness-controlled and high-quality Cr5 Si3 nanosheets that are compatible with the complementary metal-oxide-semiconductor technology are synthesized by chemical vapor deposition method. The angular dependence of electromagnetic transport properties of Cr5 Si3 nanosheets is investigated using a physical property measurement system, and an obvious topological Hall effect (THE) appears at a large tilted magnetic field, which results from the noncollinear magnetic structure of the Cr5 Si3 nanosheet. The Cr5 Si3 nanosheets exhibit distinct thickness-dependent perpendicular magnetic anisotropy (PMA), and the THE only emerges in the specific thickness range with moderate PMA. This work provides opportunities for exploring fundamental spin-related physical mechanisms of noncollinear antiferromagnet in ultrathin limit.
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Affiliation(s)
- Bailing Li
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Hongmei Zhang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Quanyang Tao
- School of Physics and Electronics, Hunan University, Changsha, 410082, P. R. China
| | - Xiaohua Shen
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Ziwei Huang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Kun He
- School of Physics and Electronics, Hunan University, Changsha, 410082, P. R. China
- Advanced Semiconductor Technology and Application Engineering Research Center of Ministry of Education of China, Changsha Semiconductor Technology and Application Innovation Research Institute, College of Semiconductors (College of Integrated Circuits), Hunan University, Changsha, 410082, P. R. China
| | - Chen Yi
- School of Physics and Electronics, Hunan University, Changsha, 410082, P. R. China
- Advanced Semiconductor Technology and Application Engineering Research Center of Ministry of Education of China, Changsha Semiconductor Technology and Application Innovation Research Institute, College of Semiconductors (College of Integrated Circuits), Hunan University, Changsha, 410082, P. R. China
| | - Xu Li
- School of Physics and Electronics, Hunan University, Changsha, 410082, P. R. China
| | - Liqiang Zhang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Zucheng Zhang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Jialing Liu
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Jingmei Tang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Yucheng Zhou
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Di Wang
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Xiangdong Yang
- Institute of Micro/Nano Materials and Devices, Ningbo University of Technology, Ningbo, 315211, P. R. China
| | - Bei Zhao
- School of Physics, Southeast University, Nanjing, 211189, P. R. China
| | - Ruixia Wu
- School of Physics and Electronics, Hunan University, Changsha, 410082, P. R. China
| | - Jia Li
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
| | - Bo Li
- Advanced Semiconductor Technology and Application Engineering Research Center of Ministry of Education of China, Changsha Semiconductor Technology and Application Innovation Research Institute, College of Semiconductors (College of Integrated Circuits), Hunan University, Changsha, 410082, P. R. China
- Shenzhen Research Institute of Hunan University, Shenzhen, 518063, P. R. China
| | - Xidong Duan
- Hunan Provincial Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
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8
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Xia J, Zhang X, Liu X, Zhou Y, Ezawa M. Universal Quantum Computation Based on Nanoscale Skyrmion Helicity Qubits in Frustrated Magnets. PHYSICAL REVIEW LETTERS 2023; 130:106701. [PMID: 36962022 DOI: 10.1103/physrevlett.130.106701] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 09/22/2022] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
We propose a skyrmion-based universal quantum computer. Skyrmions have the helicity degree of freedom in frustrated magnets, where twofold degenerated Bloch-type skyrmions are energetically favored by the magnetic dipole-dipole interaction. We construct a qubit based on them. A skyrmion must become a quantum-mechanical object when its size is of the order of nanometers. It is shown that the universal quantum computation is possible based on nanoscale skyrmions in a magnetic bilayer system. The one-qubit quantum gates are materialized by controlling the electric field and the spin current. The two-qubit gate is materialized with the use of the Ising-type exchange coupling. The merit of the present mechanism is that external magnetic field is not necessary. Our results may open a possible way toward universal quantum computation based on nanoscale topological spin textures.
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Affiliation(s)
- Jing Xia
- Department of Electrical and Computer Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Motohiko Ezawa
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan
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9
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Hou Z, Wang Q, Zhang Q, Zhang S, Zhang C, Zhou G, Gao X, Zhao G, Zhang X, Wang W, Liu J. Current-Induced Reversible Split of Elliptically Distorted Skyrmions in Geometrically Confined Fe 3 Sn 2 Nanotrack. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206106. [PMID: 36683184 PMCID: PMC10037979 DOI: 10.1002/advs.202206106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Skyrmions are swirling spin textures with topological characters promising for future spintronic applications. Skyrmionic devices typically rely on the electrical manipulation of skyrmions with a circular shape. However, manipulating elliptically distorted skyrmions can lead to numerous exotic magneto-electrical functions distinct from those of conventional circular skyrmions, significantly broadening the capability to design innovative spintronic devices. Despite the promising potential, its experimental realization so far remains elusive. In this study, the current-driven dynamics of the elliptically distorted skyrmions in geometrically confined magnet Fe3 Sn2 is experimentally explored. This study finds that the elliptical skyrmions can reversibly split into smaller-sized circular skyrmions at a current density of 3.8 × 1010 A m-2 with the current injected along their minor axis. Combined experiments with micromagnetic simulations reveal that this dynamic behavior originates from a delicate interplay of the spin-transfer torque, geometrical confinement, and pinning effect, and strongly depends on the ratio of the major axis to the minor axis of the elliptical skyrmions. The results indicate that the morphology is a new degree of freedom for manipulating the current-driven dynamics of skyrmions, providing a compelling route for the future development of spintronic devices.
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Affiliation(s)
- Zhipeng Hou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006P. R. China
| | - Qingping Wang
- College of Electronic information and automationAba Teachers UniversityPixian StreetChengdu623002China
- College of Physics and Electronic EngineeringSichuan Normal UniversityChengdu610068China
| | - Qiang Zhang
- Core Technology PlatformsNew York University Abu DhabiP.O. Box 129188Abu DhabiUnited Arab Emirates
| | - Senfu Zhang
- Physical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955‐6900Saudi Arabia
| | - Chenhui Zhang
- Physical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955‐6900Saudi Arabia
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006P. R. China
| | - Xingsen Gao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006P. R. China
| | - Guoping Zhao
- College of Physics and Electronic EngineeringSichuan Normal UniversityChengdu610068China
| | - Xixiang Zhang
- Physical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955‐6900Saudi Arabia
| | - Wenhong Wang
- School of Electronic and Information EngineeringTiangong UniversityTianjin300387China
| | - Junming Liu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced MaterialsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006P. R. China
- Laboratory of Solid State Microstructures and Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing211102China
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10
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Zhang W, Huang TX, Hehn M, Malinowski G, Verges M, Hohlfeld J, Remy Q, Lacour D, Wang XR, Zhao GP, Vallobra P, Xu Y, Mangin S, Zhao WS. Optical Creation of Skyrmions by Spin Reorientation Transition in Ferrimagnetic CoHo Alloys. ACS APPLIED MATERIALS & INTERFACES 2023; 15:5608-5619. [PMID: 36689950 DOI: 10.1021/acsami.2c19411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Manipulating magnetic skyrmions by means of a femtosecond (fs) laser pulse has attracted great interest due to their promising applications in efficient information-storage devices with ultralow energy consumption. However, the mechanism underlying the creation of skyrmions induced by an fs laser is still lacking. As a result, a key challenge is to reveal the pathway for the massive reorientation of magnetization from trivial to nontrivial topological states. Here, we studied a series of ferrimagnetic CoHo alloys and investigated the effect of a single laser pulse on the magnetic states. Thanks to the time-resolved magneto-optical Kerr effect and imaging techniques, we demonstrate that the laser-induced phase transitions from single domains into a topological skyrmion phase are mediated by the transient in-plane magnetization state, in real time and space domains, respectively. Combining experiments and micromagnetic simulations, we propose a two-step process for creating skyrmions through laser pulse irradiation: (i) the electron temperature enhancement induces a spin reorientation transition on a picosecond (ps) timescale due to the suppression of perpendicular magnetic anisotropy (PMA) and (ii) the PMA slowly restores, accompanied by out-of-plane magnetization recovery, leading to the generation of skyrmions with the help of spin fluctuations. This work provides a route to control skyrmion patterns using an fs laser, thereby establishing the foundation for further exploration of topological magnetism at ultrafast timescales.
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Affiliation(s)
- Wei Zhang
- Anhui High Reliability Chips Engineering Laboratory, Hefei Innovation Research Institute, Beihang University, Hefei230013, China
- MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing100191, China
- CNRS, IJL, Université de Lorraine, NancyF-54000, France
| | | | - Michel Hehn
- CNRS, IJL, Université de Lorraine, NancyF-54000, France
| | | | - Maxime Verges
- CNRS, IJL, Université de Lorraine, NancyF-54000, France
| | | | - Quentin Remy
- CNRS, IJL, Université de Lorraine, NancyF-54000, France
| | - Daniel Lacour
- CNRS, IJL, Université de Lorraine, NancyF-54000, France
| | - Xin Ran Wang
- MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing100191, China
| | - Guo Ping Zhao
- College of Physics and Electronic Engineering and Institute of Solid State Physics, Sichuan Normal University, Chengdu610066, China
| | - Pierre Vallobra
- Anhui High Reliability Chips Engineering Laboratory, Hefei Innovation Research Institute, Beihang University, Hefei230013, China
| | - Yong Xu
- Anhui High Reliability Chips Engineering Laboratory, Hefei Innovation Research Institute, Beihang University, Hefei230013, China
- MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing100191, China
| | | | - Wei Sheng Zhao
- Anhui High Reliability Chips Engineering Laboratory, Hefei Innovation Research Institute, Beihang University, Hefei230013, China
- MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing100191, China
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11
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Ohara K, Zhang X, Chen Y, Kato S, Xia J, Ezawa M, Tretiakov OA, Hou Z, Zhou Y, Zhao G, Yang J, Liu X. Reversible Transformation between Isolated Skyrmions and Bimerons. NANO LETTERS 2022; 22:8559-8566. [PMID: 36259745 DOI: 10.1021/acs.nanolett.2c03106] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Skyrmions and bimerons are versatile topological spin textures that can be used as information bits for both classical and quantum computing. The transformation between isolated skyrmions and bimerons is an essential operation for computing architecture based on multiple different topological bits. Here we report the creation of isolated skyrmions and their subsequent transformation to bimerons by harnessing the electric current-induced Oersted field and temperature-induced perpendicular magnetic anisotropy variation. The transformation between skyrmions and bimerons is reversible, which is controlled by the current amplitude and scanning direction. Both skyrmions and bimerons can be created in the same system through the skyrmion-bimeron transformation and magnetization switching. Deformed skyrmion bubbles and chiral labyrinth domains are found as nontrivial intermediate transition states. Our results may provide a unique way for building advanced information-processing devices using different types of topological spin textures in the same system.
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Affiliation(s)
- Kentaro Ohara
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
| | - Yinling Chen
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
| | - Satoshi Kato
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
| | - Jing Xia
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
| | - Motohiko Ezawa
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo113-8656, Japan
| | - Oleg A Tretiakov
- School of Physics, The University of New South Wales, Sydney2052, Australia
| | - Zhipeng Hou
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou510006, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen518172, Guangdong, China
| | - Guoping Zhao
- College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu610068, China
| | - Jinbo Yang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing100871, China
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano380-8553, Japan
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12
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Zhang C, Liu C, Zhang S, Zhou B, Guan C, Ma Y, Algaidi H, Zheng D, Li Y, He X, Zhang J, Li P, Hou Z, Yin G, Liu K, Peng Y, Zhang XX. Magnetic Skyrmions with Unconventional Helicity Polarization in a Van Der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204163. [PMID: 35975291 DOI: 10.1002/adma.202204163] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Skyrmion helicity, which defines the spin swirling direction, is a fundamental parameter that may be utilized to encode data bits in future memory devices. Generally, in centrosymmetric ferromagnets, dipole skyrmions with helicity of -π/2 and π/2 are degenerate in energy, leading to equal populations of both helicities. On the other hand, in chiral materials where the Dzyaloshinskii-Moriya interaction (DMI) prevails and the dipolar interaction is negligible, only a preferred helicity is selected by the type of DMI. However, whether there is a rigid boundary between these two regimes remains an open question. Herein, the observation of dipole skyrmions with unconventional helicity polarization in a van der Waals ferromagnet, Fe5- δ GeTe2 , is reported. Combining magnetometry, Lorentz transmission electron microscopy, electrical transport measurements, and micromagnetic simulations, the short-range superstructures in Fe5- δ GeTe2 resulting in a localized DMI contribution, which breaks the degeneracy of the opposite helicities and leads to the helicity polarization, is demonstrated. Therefore, the helicity feature in Fe5- δ GeTe2 is controlled by both the dipolar interaction and DMI that the former leads to Bloch-type skyrmions with helicity of ±π/2 whereas the latter breaks the helicity degeneracy. This work provides new insights into the skyrmion topology in van der Waals materials.
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Affiliation(s)
- Chenhui Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Chen Liu
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Senfu Zhang
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - Bojian Zhou
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Chaoshuai Guan
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Yinchang Ma
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Hanin Algaidi
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Dongxing Zheng
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Yan Li
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xin He
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Junwei Zhang
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, 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
| | - Gen Yin
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Kai Liu
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Yong Peng
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Xi-Xiang Zhang
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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13
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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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14
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Zhao Z, Xiao D, Chen K, Wang R, Liang L, Liu Z, Hung I, Gan Z, Hou G. Nature of Five-Coordinated Al in γ-Al 2O 3 Revealed by Ultra-High-Field Solid-State NMR. ACS CENTRAL SCIENCE 2022; 8:795-803. [PMID: 35756380 PMCID: PMC9228550 DOI: 10.1021/acscentsci.1c01497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Indexed: 05/11/2023]
Abstract
Five-coordinated Als (Al(V)) on the surface of aluminas play important roles when they are used as catalysts or catalyst supports. However, the comprehensive characterization and understanding of the intrinsic structural properties of the Al(V) remain a challenge, due to the very small amount in commonly used aluminas. Herein, the surface structures of γ-Al2O3 and Al(V)-rich Al2O3 nanosheets (Al2O3-NS) have been investigated and compared in detail by multinuclear high-field solid-state NMR. Thanks to the high resolution and sensitivity of ultra-high-field (up to 35.2 T) NMR, the arrangements of surface Als were clearly demonstrated, which are substantially different from the bulk phase in γ-Al2O3 due to the structure reconstruction. It reveals for the first time that most of the commonly observed Al(V)s tend to exist as aggregated states on the surface of γ-Al2O3, like those in amorphous Al2O3-NS liable to structure reconstruction. Our new insights into surface Al(V) species may help in understanding the structure-function relationship of alumina.
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Affiliation(s)
- Zhenchao Zhao
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Dong Xiao
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Kuizhi Chen
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Rui Wang
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Lixin Liang
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Zhengmao Liu
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Ivan Hung
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Zhehong Gan
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Guangjin Hou
- State
Key Laboratory of Catalysis, Dalian Institute
of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
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15
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Niu X, Chen BB, Zhong N, Xiang PH, Duan CG. Topological Hall effect in SrRuO 3thin films and heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:244001. [PMID: 35325882 DOI: 10.1088/1361-648x/ac60d0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/24/2022] [Indexed: 06/14/2023]
Abstract
Transition metal oxides hold a wide spectrum of fascinating properties endowed by the strong electron correlations. In 4dand 5doxides, exotic phases can be realized with the involvement of strong spin-orbit coupling (SOC), such as unconventional magnetism and topological superconductivity. Recently, topological Hall effects (THEs) and magnetic skyrmions have been uncovered in SrRuO3thin films and heterostructures, where the presence of SOC and inversion symmetry breaking at the interface are believed to play a key role. Realization of magnetic skyrmions in oxides not only offers a platform to study topological physics with correlated electrons, but also opens up new possibilities for magnetic oxides using in the low-power spintronic devices. In this review, we discuss recent observations of THE and skyrmions in the SRO film interfaced with various materials, with a focus on the electric tuning of THE. We conclude with a discussion on the directions of future research in this field.
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Affiliation(s)
- Xu Niu
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, Shanghai, 200241, People's Republic of China
| | - Bin-Bin Chen
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, Shanghai, 200241, People's Republic of China
| | - Ni Zhong
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, Shanghai, 200241, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
| | - Ping-Hua Xiang
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, Shanghai, 200241, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices (MOE) and Department of Electronics, East China Normal University, Shanghai, 200241, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
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16
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Hayami S, Motome Y. Topological spin crystals by itinerant frustration. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:443001. [PMID: 34343975 DOI: 10.1088/1361-648x/ac1a30] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/03/2021] [Indexed: 06/13/2023]
Abstract
Spin textures with nontrivial topology, such as vortices and skyrmions, have attracted attention as a source of unconventional magnetic, transport, and optical phenomena. Recently, a new generation of topological spin textures has been extensively studied in itinerant magnets; in contrast to the conventional ones induced, e.g., by the Dzyaloshinskii-Moriya interaction in noncentrosymmetric systems, they are characterized by extremely short magnetic periods and stable even in centrosymmetric systems. Here we review such new types of topological spin textures with particular emphasis on their stabilization mechanism. Focusing on the interplay between charge and spin degrees of freedom in itinerant electron systems, we show that itinerant frustration, which is the competition among electron-mediated interactions, plays a central role in stabilizing a variety of topological spin crystals including a skyrmion crystal with unconventional high skyrmion number, meron crystals, and hedgehog crystals. We also show that the essential ingredients in the itinerant frustration are represented by bilinear and biquadratic spin interactions in momentum space. This perspective not only provides a unified understanding of the unconventional topological spin crystals but also stimulates further exploration of exotic topological phenomena in itinerant magnets.
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Affiliation(s)
- Satoru Hayami
- Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Yukitoshi Motome
- Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
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17
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Psaroudaki C, Panagopoulos C. Skyrmion Qubits: A New Class of Quantum Logic Elements Based on Nanoscale Magnetization. PHYSICAL REVIEW LETTERS 2021; 127:067201. [PMID: 34420323 DOI: 10.1103/physrevlett.127.067201] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/30/2021] [Indexed: 05/05/2023]
Abstract
We introduce a new class of primitive building blocks for realizing quantum logic elements based on nanoscale magnetization textures called skyrmions. In a skyrmion qubit, information is stored in the quantum degree of helicity, and the logical states can be adjusted by electric and magnetic fields, offering a rich operation regime with high anharmonicity. By exploring a large parameter space, we propose two skyrmion qubit variants depending on their quantized state. We discuss appropriate microwave pulses required to generate single-qubit gates for quantum computing, and skyrmion multiqubit schemes for a scalable architecture with tailored couplings. Scalability, controllability by microwave fields, operation time scales, and readout by nonvolatile techniques converge to make the skyrmion qubit highly attractive as a logical element of a quantum processor.
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Affiliation(s)
- Christina Psaroudaki
- Department of Physics and Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Theoretical Physics, University of Cologne, D-50937 Cologne, Germany
| | - Christos Panagopoulos
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore
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18
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Amoroso D, Barone P, Picozzi S. Interplay between Single-Ion and Two-Ion Anisotropies in Frustrated 2D Semiconductors and Tuning of Magnetic Structures Topology. NANOMATERIALS 2021; 11:nano11081873. [PMID: 34443704 PMCID: PMC8397980 DOI: 10.3390/nano11081873] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 01/14/2023]
Abstract
The effects of competing magnetic interactions in stabilizing different spin configurations are drawing renewed attention in order to unveil emerging topological spin textures and to highlight microscopic mechanisms leading to their stabilization. The possible key role of the two-site exchange anisotropy in selecting specific helicity and vorticity of skyrmionic lattices has only recently been proposed. In this work, we explore the phase diagram of a frustrated localized magnet characterized by a two-dimensional centrosymmetric triangular lattice, focusing on the interplay between the two-ion anisotropy and the single-ion anisotropy. The effects of an external magnetic field applied perpendicularly to the magnetic layer, are also investigated. By means of Monte Carlo simulations, we find an abundance of different spin configurations, going from trivial to high-order Q skyrmionic and meronic lattices. In closer detail, we find that a dominant role is played by the two-ion over the single-ion anisotropy in determining the planar spin texture; the strength and the sign of single ion anisotropy, together with the magnitude of the magnetic field, tune the perpendicular spin components, mostly affecting the polarity (and, in turn, the topology) of the spin texture. Our analysis confirms the crucial role of the anisotropic symmetric exchange in systems with dominant short-range interactions; at the same time, we predict a rich variety of complex magnetic textures, which may arise from a fine tuning of competing anisotropic mechanisms.
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Affiliation(s)
- Danila Amoroso
- Consiglio Nazionale delle Ricerche CNR-SPIN, c/o Università degli Studi “G. D’Annunzio”, I-66100 Chieti, Italy;
- Correspondence:
| | - Paolo Barone
- Consiglio Nazionale delle Ricerche CNR-SPIN, Area della Ricerca di Tor Vergata, Via del Fosso del Cavaliere 100, I-00133 Rome, Italy;
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche CNR-SPIN, c/o Università degli Studi “G. D’Annunzio”, I-66100 Chieti, Italy;
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19
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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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20
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Heigl M, Koraltan S, Vaňatka M, Kraft R, Abert C, Vogler C, Semisalova A, Che P, Ullrich A, Schmidt T, Hintermayr J, Grundler D, Farle M, Urbánek M, Suess D, Albrecht M. Dipolar-stabilized first and second-order antiskyrmions in ferrimagnetic multilayers. Nat Commun 2021; 12:2611. [PMID: 33972515 PMCID: PMC8110839 DOI: 10.1038/s41467-021-22600-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/15/2021] [Indexed: 02/03/2023] Open
Abstract
Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities. Particularly in coexisting phases, these two types of magnetic quasi-particles may show fascinating physics and potential for spintronic devices. While skyrmions are observed in a wide range of materials, until now antiskyrmions were exclusive to materials with D2d symmetry. In this work, we show first and second-order antiskyrmions stabilized by magnetic dipole-dipole interaction in Fe/Gd-based multilayers. We modify the magnetic properties of the multilayers by Ir insertion layers. Using Lorentz transmission electron microscopy imaging, we observe coexisting antiskyrmions, Bloch skyrmions, and type-2 bubbles and determine the range of material properties and magnetic fields where the different spin objects form and dissipate. We perform micromagnetic simulations to obtain more insight into the studied system and conclude that the reduction of saturation magnetization and uniaxial magnetic anisotropy leads to the existence of this zoo of different spin objects and that they are primarily stabilized by dipolar interaction.
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Affiliation(s)
- Michael Heigl
- Institute of Physics, University of Augsburg, Augsburg, Germany.
| | - Sabri Koraltan
- Faculty of Physics, University of Vienna, Vienna, Austria
| | - Marek Vaňatka
- CEITEC BUT, Brno University of Technology, Brno, Czech Republic
| | - Robert Kraft
- Faculty of Physics, University of Vienna, Vienna, Austria
| | - Claas Abert
- Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics - Magnetism - Materials, University of Vienna, Vienna, Austria
| | | | - Anna Semisalova
- Center for Nanointegration and Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany
| | - Ping Che
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Aladin Ullrich
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Timo Schmidt
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | | | - Dirk Grundler
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Michael Farle
- Center for Nanointegration and Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany
| | - Michal Urbánek
- CEITEC BUT, Brno University of Technology, Brno, Czech Republic
| | - Dieter Suess
- Faculty of Physics, University of Vienna, Vienna, Austria
- Research Platform MMM Mathematics - Magnetism - Materials, University of Vienna, Vienna, Austria
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21
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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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22
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Streubel R, Bouma DS, Bruni F, Chen X, Ercius P, Ciston J, N'Diaye AT, Roy S, Kevan SD, Fischer P, Hellman F. Chiral Spin Textures in Amorphous Iron-Germanium Thick Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004830. [PMID: 33432657 DOI: 10.1002/adma.202004830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 12/02/2020] [Indexed: 06/12/2023]
Abstract
Topological solitary fields, such as magnetic and polar skyrmions, are envisioned to revolutionize microelectronics. These configurations have been stabilized in solid-state materials with a global inversion symmetry breaking, which translates in magnetic materials into a vector spin exchange known as the Dzyaloshinskii-Moriya interaction (DMI), as well as spin chirality selection and isotropic solitons. This work reports experimental evidence of 3D chiral spin textures, such as helical spins and skyrmions with different chirality and topological charge, stabilized in amorphous Fe-Ge thick films. These results demonstrate that structurally and chemically disordered materials with a random DMI can resemble inversion symmetry broken systems with similar magnetic properties, moments, and states. Disordered systems are distinguished from systems with global inversion symmetry breaking by their degenerate spin chirality that allows for forming isotropic and anisotropic topological spin textures at remanence, while offering greater flexibility in materials synthesis, voltage, and strain manipulation.
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Affiliation(s)
- Robert Streubel
- Department of Physics and Astronomy, and Nebraska, Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - D Simca Bouma
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Frank Bruni
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Xiaoqian Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Peter Ercius
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jim Ciston
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sujoy Roy
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Steve D Kevan
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Frances Hellman
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
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23
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Coexistence of distinct skyrmion phases observed in hybrid ferromagnetic/ferrimagnetic multilayers. Nat Commun 2020; 11:6365. [PMID: 33311480 PMCID: PMC7733481 DOI: 10.1038/s41467-020-20025-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/11/2020] [Indexed: 11/11/2022] Open
Abstract
Materials hosting magnetic skyrmions at room temperature could enable compact and energetically-efficient storage such as racetrack memories, where information is coded by the presence/absence of skyrmions forming a moving chain through the device. The skyrmion Hall effect leading to their annihilation at the racetrack edges can be suppressed, for example, by antiferromagnetically-coupled skyrmions. However, avoiding modifications of the inter-skyrmion distances remains challenging. As a solution, a chain of bits could also be encoded by two different solitons, such as a skyrmion and a chiral bobber, with the limitation that it has solely been realized in B20-type materials at low temperatures. Here, we demonstrate that a hybrid ferro/ferri/ferromagnetic multilayer system can host two distinct skyrmion phases at room temperature, namely tubular and partial skyrmions. Furthermore, the tubular skyrmion can be converted into a partial skyrmion. Such systems may serve as a platform for designing memory applications using distinct skyrmion types. Topological spin textures are of technological interest due to their potential as a store of information. Here the authors experimentally demonstrate two distinct topological spin textures, tubular and incomplete skyrmions, and their mutual conversion in a ferromagnetic/ferromagnetic heterostructure.
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24
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Spontaneous skyrmionic lattice from anisotropic symmetric exchange in a Ni-halide monolayer. Nat Commun 2020; 11:5784. [PMID: 33188198 PMCID: PMC7666143 DOI: 10.1038/s41467-020-19535-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/02/2020] [Indexed: 11/09/2022] Open
Abstract
Topological spin structures, such as magnetic skyrmions, hold great promises for data storage applications, thanks to their inherent stability. In most cases, skyrmions are stabilized by magnetic fields in non-centrosymmetric systems displaying the chiral Dzyaloshinskii-Moriya exchange interaction, while spontaneous skyrmion lattices have been reported in centrosymmetric itinerant magnets with long-range interactions. Here, a spontaneous anti-biskyrmion lattice with unique topology and chirality is predicted in the monolayer of a semiconducting and centrosymmetric metal halide, NiI2. Our first-principles and Monte Carlo simulations reveal that the anisotropies of the short-range symmetric exchange, when combined with magnetic frustration, can lead to an emergent chiral interaction that is responsible for the predicted topological spin structures. The proposed mechanism finds a prototypical manifestation in two-dimensional magnets, thus broadening the class of materials that can host spontaneous skyrmionic states.
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25
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Skyrmions and Spin Waves in Magneto-Ferroelectric Superlattices. ENTROPY 2020; 22:e22080862. [PMID: 33286633 PMCID: PMC7517463 DOI: 10.3390/e22080862] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/29/2020] [Accepted: 08/01/2020] [Indexed: 12/02/2022]
Abstract
We present in this paper the effects of Dzyaloshinskii–Moriya (DM) magneto–electric coupling between ferroelectric and magnetic interface atomic layers in a superlattice formed by alternate magnetic and ferroelectric films. We consider two cases: magnetic and ferroelectric films have the simple cubic lattice and the triangular lattice. In the two cases, magnetic films have Heisenberg spins interacting with each other via an exchange J and a DM interaction with the ferroelectric interface. The electrical polarizations of ±1 are assumed for the ferroelectric films. We determine the ground-state (GS) spin configuration in the magnetic film and study the phase transition in each case. In the simple cubic lattice case, in zero field, the GS is periodically non collinear (helical structure) and in an applied field H perpendicular to the layers, it shows the existence of skyrmions at the interface. Using the Green’s function method we study the spin waves (SW) excited in a monolayer and also in a bilayer sandwiched between ferroelectric films, in zero field. We show that the DM interaction strongly affects the long-wave length SW mode. We calculate also the magnetization at low temperatures. We use next Monte Carlo simulations to calculate various physical quantities at finite temperatures such as the critical temperature, the layer magnetization and the layer polarization, as functions of the magneto–electric DM coupling and the applied magnetic field. Phase transition to the disordered phase is studied. In the case of the triangular lattice, we show the formation of skyrmions even in zero field and a skyrmion crystal in an applied field when the interface coupling between the ferroelectric film and the ferromagnetic film is rather strong. The skyrmion crystal is stable in a large region of the external magnetic field. The phase transition is studied.
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26
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Capic D, Garanin DA, Chudnovsky EM. Skyrmion-skyrmion interaction in a magnetic film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:415803. [PMID: 32526724 DOI: 10.1088/1361-648x/ab9bc8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
Interaction of two skyrmions stabilized by the ferromagnetic exchange, Dzyaloshinskii-Moriya interaction (DMI), and external magnetic field has been studied numerically on a 2D lattice of size large compared to the separation,d, between the skyrmions. We show that two skyrmions of the same chirality (determined by the symmetry of the crystal) repel. In accordance with earlier analytical results, their long-range pair interaction falls out with the separation as exp(-d/δH), whereδHis the magnetic screening length, independent of the DMI. The prefactor in this expression depends on the DMI that drives the repulsion. The latter results in the spiral motion of the two skyrmions around each other, with the separation between them growing logarithmically with time. When two skyrmions of the total topological chargeQ= 2 are pushed close to each other, the discreteness of the atomic lattice makes them collapse into one skyrmion of chargeQ= 1 below a critical separation. Experiment is proposed that would allow one to measure the interaction between two skyrmions by holding them in positions with two magnetic tips. Our findings should be of value for designing topologically protected magnetic memory based upon skyrmions.
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Affiliation(s)
- D Capic
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
| | - D A Garanin
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
| | - E M Chudnovsky
- Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America
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27
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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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28
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Jena J, Göbel B, Ma T, Kumar V, Saha R, Mertig I, Felser C, Parkin SSP. Elliptical Bloch skyrmion chiral twins in an antiskyrmion system. Nat Commun 2020; 11:1115. [PMID: 32111842 PMCID: PMC7048809 DOI: 10.1038/s41467-020-14925-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 02/12/2020] [Indexed: 11/22/2022] Open
Abstract
Skyrmions and antiskyrmions are distinct topological chiral spin textures that have been observed in various material systems depending on the symmetry of the crystal structure. Here we show, using Lorentz transmission electron microscopy, that arrays of skyrmions can be stabilized in a tetragonal inverse Heusler with D2d symmetry whose Dzyaloshinskii-Moriya interaction (DMI) otherwise supports antiskyrmions. These skyrmions can be distinguished from those previously found in several B20 systems which have only one chirality and are circular in shape. We find Bloch-type elliptical skyrmions with opposite chiralities whose major axis is oriented along two specific crystal directions: [010] and [100]. These structures are metastable over a wide temperature range and we show that they are stabilized by long-range dipole-dipole interactions. The possibility of forming two distinct chiral spin textures with opposite topological charges of ±1 in one material makes the family of D2d materials exceptional. Skyrmions and anti-skyrmions often exist in distinct material systems. Here, the authors observe elliptical skyrmions and anti-skyrmions with opposite topological charges in one tetragonal Heusler compound Mn1.4Pt0.9Pd0.1Sn with D2d symmetry.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Tianping Ma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Rana Saha
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Ingrid Mertig
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.
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29
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Murooka R, Leonov AO, Inoue K, Ohe JI. Current-induced shuttlecock-like movement of non-axisymmetric chiral skyrmions. Sci Rep 2020; 10:396. [PMID: 31941954 PMCID: PMC6962387 DOI: 10.1038/s41598-019-56791-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 10/17/2019] [Indexed: 11/09/2022] Open
Abstract
Current-induced motion of non-axisymmetric skyrmions within tilted ferromagnetic phases of polar helimagnets with the easy plane anisotropy is studied by micromagnetic simulations. Such non-axisymmetric skyrmions consist of a circular core and a crescent-shaped domain-wall region formed with respect to the tilted surrounding state. Current-driven motion of non-axisymmetric skyrmions exhibits two distinct time regimes: initially the skyrmions rotate towards the current flow direction and subsequently move along the current with the skyrmionic crescent first. According to the Thiele equation, the asymmetric distribution of the topological charge and the dissipative force tensor play an important role for giving the different velocities for the circular and the crescent-shaped constituent parts of the skyrmion what underlies such a shuttlecock-like movement. Moreover, the current-velocity relation depends on the angle of the tilted ferromagnetic phase what makes in particular the transverse velocity of skyrmions sensitive to their field-driven configurational transformation. We also argue the possibility of magnetic racetrack waveguides based on complex interplay of robust asymmetric skyrmions with multiple twisted edge states.
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Affiliation(s)
- Remi Murooka
- Department of Physics, Toho University, 2-2-1 Miyama, Funabashi, Chiba, Japan
| | - Andrey O Leonov
- Chirality Research Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8526, Japan. .,Department of Chemistry, Faculty of Science, Hiroshima University Kagamiyama, Higashi Hiroshima, Hiroshima, 739-8526, Japan. .,IFW Dresden, Postfach 270016, D-01171, Dresden, Germany.
| | - Katsuya Inoue
- Chirality Research Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8526, Japan. .,Department of Chemistry, Faculty of Science, Hiroshima University Kagamiyama, Higashi Hiroshima, Hiroshima, 739-8526, Japan.
| | - Jun-Ichiro Ohe
- Department of Physics, Toho University, 2-2-1 Miyama, Funabashi, Chiba, Japan.
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30
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Hou Z, Zhang Q, Zhang X, Xu G, Xia J, Ding B, Li H, Zhang S, Batra NM, Costa PMFJ, Liu E, Wu G, Ezawa M, Liu X, Zhou Y, Zhang X, Wang W. Current-Induced Helicity Reversal of a Single Skyrmionic Bubble Chain in a Nanostructured Frustrated Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904815. [PMID: 31746047 DOI: 10.1002/adma.201904815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/14/2019] [Indexed: 06/10/2023]
Abstract
Helicity indicates the in-plane magnetic-moment swirling direction of a skyrmionic configuration. The ability to reverse the helicity of a skyrmionic bubble via purely electrical means has been predicted in frustrated magnetic systems; however, it has been challenging to observe this experimentally. The current-driven helicity reversal of the skyrmionic bubble in a nanostructured frustrated Fe3 Sn2 magnet is experimentally demonstrated. The critical current density required to trigger the helicity reversal is 109 -1010 A m-2 , with a corresponding pulse-width varying from 1 µs to 100 ns. Computational simulations reveal that both the pinning effect and dipole-dipole interaction play a crucial role in the helicity reversal process.
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Affiliation(s)
- Zhipeng Hou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Institute for Advanced Materials, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China
| | - Qiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Xichao Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Guizhou Xu
- School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Bei Ding
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Senfu Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Nitin M Batra
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Pedro M F J Costa
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Enke Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Guangheng Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Motohiko Ezawa
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, 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, China
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Wenhong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
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31
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Skyrmion Crystals and Phase Transitions in Magneto-Ferroelectric Superlattices: Dzyaloshinskii–Moriya Interaction in a Frustrated J1 − J2 Model. Symmetry (Basel) 2019. [DOI: 10.3390/sym12010026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The formation of a skyrmion crystal and its phase transition are studied, taking into account the Dzyaloshinskii–Moriya (DM) interaction at the interface between a ferroelectric layer and a magnetic layer in a superlattice. Frustration is introduced in both magnetic and ferroelectric films. The films have a simple cubic lattice structure. The spins inside the magnetic layers are Heisenberg spins interacting with each other via nearest-neighbor (NN) exchange J m and next-nearest-neighbor (NNN) exchange J 2 m . The polarizations in the ferroelectric layers are assumed to be of Ising type with NN and NNN interactions J f and J 2 f . At the magnetoelectric interface, a DM interaction J m f between spins and polarizations is supposed. The spin configuration in the ground state is calculated by the steepest descent method. In an applied magnetic field H perpendicular to the layers, we show that the formation of skyrmions at the magnetoelectric interface is strongly enhanced by the frustration brought about by the NNN antiferromagnetic interactions J 2 m and J 2 f . Various physical quantities at finite temperatures are obtained by Monte Carlo simulations. We show the critical temperature, the order parameters of magnetic and ferroelectric layers as functions of the interface DM coupling, the applied magnetic field, and J 2 m and J 2 f . The phase transition to the disordered phase is studied in detail.
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Valiulin VE, Mikheyenkov AV, Chtchelkatchev NM, Barabanov AF. Continuous transformation between ferro and antiferro circular structures in [Formula: see text] frustrated Heisenberg model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:455801. [PMID: 31344692 DOI: 10.1088/1361-648x/ab35cc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Frustrated magnetic compounds, in particular low-dimensional, are topical research due to the persistent uncovering of novel nontrivial quantum states and potential applications. The problem of this field is that many important results are scattered over the localized parameter ranges, while areas in between still contain hidden interesting effects. We consider the [Formula: see text] Heisenberg model on the square lattice and use the spherically symmetric self-consistent approach for spin-spin Green's functions in 'quasielastic' approximation. We have found a new local order in spin liquids: antiferromagnetic isotropical helices. On the structure factor we see circular concentric dispersionless structures, while on any radial direction the excitation spectrum has 'roton' minima. That implies nontrivial magnetic excitations and consequences in magnetic susceptibility and thermodynamics. On the [Formula: see text] exchange parameters globe we discover a crossover between antiferromagnetic-like local order and ferromagnetic-like; we find stripe-like order in the middle. In fact, our 'quasielastic' approach allows investigation of the whole [Formula: see text] globe.
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Affiliation(s)
- V E Valiulin
- Institute for High Pressure Physics, Russian Academy of Sciences, Moscow (Troitsk) 108840, Russia. Department of Theoretical Physics, Moscow Institute of Physics and Technology (State University), Moscow 141700, Russia. National Research Centre 'Kurchatov Institute', Moscow 123182, Russia
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Abstract
Abstract
In this article, we focus on (1) type-II multiferroics driven by spiral spin orderings and (2) magnetoelectric couplings in multiferroic skyrmion-hosting materials. We present both phenomenological understanding and microscopic mechanisms for spiral spin state, which is one of the essential starting points for type-II multiferroics and magnetic skyrmions. Two distinct mechanisms of spiral spin states (frustration and Dzyaloshinskii–Moriya [DM] interaction) are discussed in the context of the lattice symmetry. We also discuss the spin-induced ferroelectricity on the basis of the symmetry and microscopic atomic configurations. We compare two well-known microscopic models: the generalized inverse DM mechanism and the metal-ligand d-p hybridization mechanism. As a test for these models, we summarize the multiferroic properties of a family of triangular-lattice antiferromagnets. We also give a brief review of the magnetic skyrmions. Three types of known skyrmion-hosting materials with multiferroicity are discussed from the view point of crystal structure, magnetism, and origins of the magnetoelectric couplings. For exploration of new skyrmion-hosting materials, we also discuss the theoretical models for stabilizing skyrmions by magnetic frustration in centrosymmetric system. Several basic ideas for material design are given, which are successfully demonstrated by the recent experimental evidences for the skyrmion formation in centrosymmetric frustrated magnets.
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Affiliation(s)
- Takashi Kurumaji
- Physics , Massachusetts Institute of Technology , Cambridge , MA, USA
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Kurumaji T, Nakajima T, Hirschberger M, Kikkawa A, Yamasaki Y, Sagayama H, Nakao H, Taguchi Y, Arima TH, Tokura Y. Skyrmion lattice with a giant topological Hall effect in a frustrated triangular-lattice magnet. Science 2019; 365:914-918. [DOI: 10.1126/science.aau0968] [Citation(s) in RCA: 262] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/30/2019] [Indexed: 11/02/2022]
Abstract
Geometrically frustrated magnets can host complex spin textures, leading to unconventional electromagnetic responses. Magnetic frustration may also promote topologically nontrivial spin states such as magnetic skyrmions. Experimentally, however, skyrmions have largely been observed in noncentrosymmetric lattice structures or interfacial symmetry-breaking heterostructures. Here, we report the emergence of a Bloch-type skyrmion state in the frustrated centrosymmetric triangular-lattice magnet Gd2PdSi3. We observed a giant topological Hall response, indicating a field-induced skyrmion phase, which is further corroborated by the observation of in-plane spin modulation probed by resonant x-ray scattering. Our results may lead to further discoveries of emergent electrodynamics in magnetically frustrated centrosymmetric materials.
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Göbel B, Henk J, Mertig I. Forming individual magnetic biskyrmions by merging two skyrmions in a centrosymmetric nanodisk. Sci Rep 2019; 9:9521. [PMID: 31266991 PMCID: PMC6606756 DOI: 10.1038/s41598-019-45965-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/17/2019] [Indexed: 11/25/2022] Open
Abstract
When two magnetic skyrmions - whirl-like, topologically protected quasiparticles - form a bound pair, a biskyrmion state with a topological charge of NSk = ±2 is constituted. Recently, especially the case of two partially overlapping skyrmions has brought about great research interest. Since for its formation the individual skyrmions need to posses opposite in-plane magnetizations, such a biskyrmion cannot be stabilized by the Dzyaloshinskii-Moriya-interaction (DMI), which is the interaction that typically stabilizes skyrmions in non-centrosymmetric materials and at interfaces. Here, we show that these biskyrmions can be stabilized by the dipole-dipole interaction in centrosymmetric materials in which the DMI is forbidden. Analytical considerations indicate that the bound state of a biskyrmion is energetically preferable over two individual skyrmions. As a result, when starting from two skyrmions in a micromagnetic simulation, a biskyrmion is formed upon relaxation. We propose a scheme that allows to control this biskyrmion formation in nanodisks and analyze the individual steps.
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Affiliation(s)
- Börge Göbel
- Max-Planck-Institut für Mikrostrukturphysik, Halle (Saale), 06120, Germany.
| | - Jürgen Henk
- Martin-Luther-Universität Halle-Wittenberg, Institut für Physik, Halle (Saale), 06099, Germany
| | - Ingrid Mertig
- Max-Planck-Institut für Mikrostrukturphysik, Halle (Saale), 06120, Germany
- Martin-Luther-Universität Halle-Wittenberg, Institut für Physik, Halle (Saale), 06099, Germany
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Loudon JC, Twitchett‐Harrison AC, Cortés‐Ortuño D, Birch MT, Turnbull LA, Štefančič A, Ogrin FY, Burgos‐Parra EO, Bukin N, Laurenson A, Popescu H, Beg M, Hovorka O, Fangohr H, Midgley PA, Balakrishnan G, Hatton PD. Do Images of Biskyrmions Show Type-II Bubbles? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1806598. [PMID: 30844122 PMCID: PMC9285551 DOI: 10.1002/adma.201806598] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/31/2019] [Indexed: 06/09/2023]
Abstract
The intense research effort investigating magnetic skyrmions and their applications for spintronics has yielded reports of more exotic objects including the biskyrmion, which consists of a bound pair of counter-rotating vortices of magnetization. Biskyrmions have been identified only from transmission electron microscopy images and have not been observed by other techniques, nor seen in simulations carried out under realistic conditions. Here, quantitative Lorentz transmission electron microscopy, X-ray holography, and micromagnetic simulations are combined to search for biskyrmions in MnNiGa, a material in which they have been reported. Only type-I and type-II magnetic bubbles are found and images purported to show biskyrmions can be explained as type-II bubbles viewed at an angle to their axes. It is not the magnetization but the magnetic flux density resulting from this object that forms the counter-rotating vortices.
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Affiliation(s)
- James C. Loudon
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
| | | | - David Cortés‐Ortuño
- Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Max T. Birch
- Department of PhysicsUniversity of DurhamDurhamDH1 3LEUK
| | | | - Aleš Štefančič
- Department of PhysicsUniversity of WarwickCoventryCV4 7ALUK
| | - Feodor Y. Ogrin
- School of Physics and AstronomyUniversity of ExeterExeterEX4 4QLUK
| | | | - Nicholas Bukin
- School of Physics and AstronomyUniversity of ExeterExeterEX4 4QLUK
| | - Angus Laurenson
- School of Physics and AstronomyUniversity of ExeterExeterEX4 4QLUK
| | - Horia Popescu
- Synchrotron SOLEILSaint Aubin, BP 4891192Gif‐sur‐YvetteFrance
| | - Marijan Beg
- Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
- European XFEL GmbHHolzkoppel 422869SchenefeldGermany
| | - Ondrej Hovorka
- Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Hans Fangohr
- Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
- European XFEL GmbHHolzkoppel 422869SchenefeldGermany
| | - Paul A. Midgley
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
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Hou Z, Zhang Q, Xu G, Zhang S, Gong C, Ding B, Li H, Xu F, Yao Y, Liu E, Wu G, Zhang XX, Wang W. Manipulating the Topology of Nanoscale Skyrmion Bubbles by Spatially Geometric Confinement. ACS NANO 2019; 13:922-929. [PMID: 30605309 DOI: 10.1021/acsnano.8b09689] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The discovery of magnetic skyrmion bubbles in centrosymmetric magnets has been receiving increasing interest from the research community, due to the fascinating physics of topological spin textures and its possible applications to spintronics. However, key challenges remain, such as how to manipulate the nucleation of skyrmion bubbles to exclude the trivial bubbles or metastable skyrmion bubbles that usually coexist with skyrmion bubbles in the centrosymmetric magnets. Here, we report having performed this task by applying spatially geometric confinement to a centrosymmetric frustrated Fe3Sn2 magnet. We demonstrate that the spatially geometric confinement can indeed stabilize the skyrmion bubbles by effectively suppressing the formation of trivial bubbles and metastable skyrmion bubbles. We also show that the critical magnetic field for the nucleation of the skyrmion bubbles in the confined Fe3Sn2 nanostripes is drastically less, by an order of magnitude, than that required in the thin plate without geometrical confinement. By analyzing how the width and thickness of the nanostripes affect the spin textures of skyrmion bubbles, we infer that the topological transition of skyrmion bubbles is closely related to the dipole-dipole interaction, which we find is consistent with theoretical simulations. The results presented here bring us closer to achieving the fabrication of skyrmion-based racetrack memory devices.
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Affiliation(s)
- Zhipeng Hou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
- Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Saudi Arabia
| | - Qiang Zhang
- Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Saudi Arabia
| | - Guizhou Xu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Senfu Zhang
- Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Saudi Arabia
| | - Chen Gong
- Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Saudi Arabia
| | - Bei Ding
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Hang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Feng Xu
- School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Yuan Yao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Enke Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Guangheng Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Xi-Xiang Zhang
- Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Saudi Arabia
| | - Wenhong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
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Streubel R, Kent N, Dhuey S, Scholl A, Kevan S, Fischer P. Spatial and Temporal Correlations of XY Macro Spins. NANO LETTERS 2018; 18:7428-7434. [PMID: 30248262 DOI: 10.1021/acs.nanolett.8b01789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We use nano disk arrays with square and honeycomb symmetry to investigate magnetic phases and spin correlations of XY dipolar systems at the micro scale. Utilizing magnetization sensitive X-ray photoemission electron microscopy, we probe magnetic ground states and the "order-by-disorder" phenomenon predicted 30 years ago. We observe the antiferromagnetic striped ground state in square lattices, and 6-fold symmetric structures, including trigonal vortex lattices and disordered floating vortices, in the honeycomb lattice. The spin frustration in the honeycomb lattice causes a phase transition from a long-range ordered locked phase over a floating phase with quasi long-range order and indications of a Berezinskii-Thouless-Kosterlitz-like character, to the thermally excited paramagnetic state. Absent spatial correlation and quasi periodic switching of isolated vortices in the quasi long-range ordered phase suggest a degeneracy of the vortex circulation.
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Affiliation(s)
- Robert Streubel
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
| | - Noah Kent
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
- Physics Department , UC Santa Cruz , Santa Cruz California 95064 , United States
| | - Scott Dhuey
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
| | - Andreas Scholl
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
| | - Steve Kevan
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
- Department of Physics , University of Oregon , Eugene , Oregon 97401 , United States
| | - Peter Fischer
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley California 94720 , United States
- Physics Department , UC Santa Cruz , Santa Cruz California 95064 , United States
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Büttner F, Lemesh I, Beach GSD. Theory of isolated magnetic skyrmions: From fundamentals to room temperature applications. Sci Rep 2018. [PMID: 29535320 PMCID: PMC5849609 DOI: 10.1038/s41598-018-22242-8] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Magnetic skyrmions are topological quasiparticles of great interest for data storage applications because of their small size, high stability, and ease of manipulation via electric current. However, although models exist for some limiting cases, there is no universal theory capable of accurately describing the structure and energetics of all skyrmions. The main barrier is the complexity of non-local stray field interactions, which are usually included through crude approximations. Here we present an accurate analytical framework to treat isolated skyrmions in any material, assuming only a circularly-symmetric 360° domain wall profile and a homogeneous magnetization profile in the out-of-plane direction. We establish the first rigorous criteria to distinguish stray field from DMI skyrmions, resolving a major dispute in the community. We discover new phases, such as bi-stability, a phenomenon unknown in magnetism so far. We predict materials for sub-10 nm zero field room temperature stable skyrmions suitable for applications. Finally, we derive analytical equations to describe current-driven dynamics, find a topological damping, and show how to engineer materials in which compact skyrmions can be driven at velocities >1000 m/s.
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Affiliation(s)
- Felix Büttner
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
| | - Ivan Lemesh
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
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Hoffmann M, Zimmermann B, Müller GP, Schürhoff D, Kiselev NS, Melcher C, Blügel S. Antiskyrmions stabilized at interfaces by anisotropic Dzyaloshinskii-Moriya interactions. Nat Commun 2017; 8:308. [PMID: 28827700 PMCID: PMC5566362 DOI: 10.1038/s41467-017-00313-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 06/15/2017] [Indexed: 11/09/2022] Open
Abstract
Chiral magnets are an emerging class of topological matter harboring localized and topologically protected vortex-like magnetic textures called skyrmions, which are currently under intense scrutiny as an entity for information storage and processing. Here, on the level of micromagnetics we rigorously show that chiral magnets can not only host skyrmions but also antiskyrmions as least energy configurations over all non-trivial homotopy classes. We derive practical criteria for their occurrence and coexistence with skyrmions that can be fulfilled by (110)-oriented interfaces depending on the electronic structure. Relating the electronic structure to an atomistic spin-lattice model by means of density functional calculations and minimizing the energy on a mesoscopic scale by applying spin-relaxation methods, we propose a double layer of Fe grown on a W(110) substrate as a practical example. We conjecture that ultra-thin magnetic films grown on semiconductor or heavy metal substrates with C 2v symmetry are prototype classes of materials hosting magnetic antiskyrmions.Skyrmions, localized defects in the magnetization, can be stabilised in materials by the Dzyaloshinskii-Moriya interaction (DMI). Hoffmann et al. predict that, when the DMI is anisotropic, antiskyrmions can be formed and coexist with skyrmions, enabling studies and exploitation of their interactions.
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Affiliation(s)
- Markus Hoffmann
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany.
| | - Bernd Zimmermann
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Gideon P Müller
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
- Science Institute of the University of Iceland, VR-III, 107, Reykjavík, Iceland
| | - Daniel Schürhoff
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Nikolai S Kiselev
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Christof Melcher
- Department of Mathematics I & JARA FIT, RWTH Aachen University, 52056, Aachen, Germany
| | - Stefan Blügel
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
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