1
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Yu J, Liu Y, Ke Y, Su J, Cao J, Li Z, Sun B, Bai H, Wang W. Observation of Topological Hall Effect in a Chemically Complex Alloy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2308415. [PMID: 38265890 DOI: 10.1002/adma.202308415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 12/28/2023] [Indexed: 01/26/2024]
Abstract
The topological Hall effect (THE) is the transport response of chiral spin textures and thus can serve as a powerful probe for detecting and understanding these unconventional magnetic orders. So far, the THE is only observed in either noncentrosymmetric systems where spin chirality is stabilized by Dzyaloshinskii-Moriya interactions, or triangular-lattice magnets with Ruderman-Kittel-Kasuya-Yosida-type interactions. Here, a pronounced THE is observed in a Fe-Co-Ni-Mn chemically complex alloy with a simple face-centered cubic (fcc) structure across a wide range of temperatures and magnetic fields. The alloy is shown to have a strong magnetic frustration owing to the random occupation of magnetic atoms on the close-packed fcc lattice and the direct Heisenberg exchange interaction among atoms, as evidenced by the appearance of a reentrant spin glass state in the low-temperature regime and the first principles calculations. Consequently, THE is attributed to the nonvanishing spin chirality created by strong spin frustration under the external magnetic field, which is distinct from the mechanism responsible for the skyrmion systems, as well as geometrically frustrated magnets.
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Affiliation(s)
- Jihao Yu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuying Liu
- School of Physical Science and Technology, Guangxi University, Nanning, 530004, China
| | - Yubin Ke
- Spallation Neutron Source Science Center, Dongguan, 523803, China
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiaqi Su
- School of Physical Science and Technology, Guangxi University, Nanning, 530004, China
| | - Jingshan Cao
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zian Li
- School of Physical Science and Technology, Guangxi University, Nanning, 530004, China
| | - Baoan Sun
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Haiyang Bai
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Weihua Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
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2
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Bera S. Role of isotropic and anisotropic Dzyaloshinskii-Moriya interaction on skyrmions, merons and antiskyrmions in the Cnvsymmetric system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:195805. [PMID: 38316047 DOI: 10.1088/1361-648x/ad266f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
The lattice Hamiltonian with the presence of a chiral magnetic isotropic Dzyaloshinskii-Moriya interaction (DMI) in a square and hexagonal lattice is numerically solved to give the full phase diagram consisting of skyrmions and merons in different parameter planes. The phase diagram provides the actual regions of analytically unresolved asymmetric skyrmions and merons, and it is found that these regions are substantially larger than those of symmetric skyrmions and merons. With magnetic field, a change from meron or spin spiral (SS) to skyrmion is seen. The complete phase diagram for theCnvsymmetric system with anisotropic DMI is drawn and it is shown that this DMI helps to change the SS propagation direction. Finally, the well-defined region of a thermodynamically stable antiskyrmion phase in theCnvsymmetric system is shown.
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Affiliation(s)
- Sandip Bera
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada
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3
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Jin Z, Yao X, Wang Z, Yuan HY, Zeng Z, Wang W, Cao Y, Yan P. Nonlinear Topological Magnon Spin Hall Effect. PHYSICAL REVIEW LETTERS 2023; 131:166704. [PMID: 37925727 DOI: 10.1103/physrevlett.131.166704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/03/2023] [Accepted: 09/15/2023] [Indexed: 11/07/2023]
Abstract
When a magnon passes through two-dimensional magnetic textures, it will experience a fictitious magnetic field originating from the 3×3 skew-symmetric gauge fields. To date, only one of the three independent components of the gauge fields has been found to play a role in generating the fictitious magnetic field, while the other two are perfectly hidden. In this Letter, we show that they are concealed in the nonlinear magnon transport in magnetic textures. Without loss of generality, we theoretically study the nonlinear magnon-skyrmion interaction in antiferromagnets. By analyzing the scattering features of three-magnon processes between the circularly polarized incident magnon and breathing skyrmion, we predict a giant Hall angle of both the confluence and splitting modes. Furthermore, we find that the Hall angle reverses its sign when one switches the handedness of the incident magnons. We dub this the nonlinear topological magnon spin Hall effect. Our findings are deeply rooted in the bosonic nature of magnons that the particle number is not conserved, which has no counterpart in low-energy fermionic systems and may open the door for probing gauge fields by nonlinear means.
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Affiliation(s)
- Zhejunyu Jin
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Xianglong Yao
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Zhenyu Wang
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - H Y Yuan
- Institute for Theoretical Physics, Utrecht University, 3584 CC Utrecht, Netherlands
| | - Zhaozhuo Zeng
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Weiwei Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Yunshan Cao
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Peng Yan
- School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
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4
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Ghosh S, Low A, Ghorai S, Mandal K, Thirupathaiah S. Tuning of electrical, magnetic, and topological properties of magnetic Weyl semimetal Mn3+xGe by Fe doping. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:485701. [PMID: 37604158 DOI: 10.1088/1361-648x/acf262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 08/21/2023] [Indexed: 08/23/2023]
Abstract
We report on the tuning of electrical, magnetic, and topological properties of the magnetic Weyl semimetal (Mn3+xGe) by Fe doping at the Mn site, Mn(3+x)-δFeδGe (δ= 0, 0.30, and 0.62). Fe doping significantly changes the electrical and magnetic properties of Mn3+xGe. The resistivity of the parent compound displays metallic behavior, the system withδ= 0.30 of Fe doping exhibits semiconducting or bad-metallic behavior, and the system withδ= 0.62 of Fe doping demonstrates a metal-insulator transition at around 100 K. Further, we observe that the Fe doping increases in-plane ferromagnetism, magnetocrystalline anisotropy, and induces a spin-glass state at low temperatures. Surprisingly, topological Hall state has been noticed at a Fe doping ofδ= 0.30 that is not found in the parent compound or withδ= 0.62 of Fe doping. In addition, spontaneous anomalous Hall effect observed in the parent system is significantly reduced with increasing Fe doping concentration.
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Affiliation(s)
- Susanta Ghosh
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
| | - Achintya Low
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
| | - Soumya Ghorai
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
| | - Kalyan Mandal
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
| | - Setti Thirupathaiah
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
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5
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Causer GL, Chacon A, Heinemann A, Pfleiderer C. Small-angle neutron scattering of long-wavelength magnetic modulations in reduced sample dimensions. J Appl Crystallogr 2023; 56:26-35. [PMID: 36777147 PMCID: PMC9901922 DOI: 10.1107/s1600576722010755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/10/2022] [Indexed: 12/23/2022] Open
Abstract
Magnetic small-angle neutron scattering (SANS) is ideally suited to providing direct reciprocal-space information on long-wavelength magnetic modulations, such as helicoids, solitons, merons or skyrmions. SANS of such structures in thin films or micro-structured bulk materials is strongly limited by the tiny scattering volume vis a vis the prohibitively high background scattering by the substrate and support structures. Considering near-surface scattering just above the critical angle of reflection, where unwanted signal contributions due to substrate or support structures become very small, it is established that the scattering patterns of the helical, conical, skyrmion lattice and fluctuation-disordered phases in a polished bulk sample of MnSi are equivalent for conventional transmission and near-surface SANS geometries. This motivates the prediction of a complete repository of scattering patterns expected for thin films in the near-surface SANS geometry for each orientation of the magnetic order with respect to the scattering plane.
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Affiliation(s)
- Grace L. Causer
- Physik-Department, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany,Correspondence e-mail:
| | - Alfonso Chacon
- Physik-Department, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - André Heinemann
- Heinz Maier-Leibnitz Zentrum (MLZ), Technical University of Munich, D-85748 Garching, Germany
| | - Christian Pfleiderer
- Physik-Department, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany,Centre for Quantum Engineering (ZQE), Technical University of Munich, D-85748 Garching, Germany,Munich Center for Quantum Science and Technology (MCQST), Technical University of Munich, D-85748 Garching, Germany
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6
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Zhang C, Liu C, Zhang J, Yuan Y, Wen Y, Li Y, Zheng D, Zhang Q, Hou Z, Yin G, Liu K, Peng Y, Zhang XX. Room-Temperature Magnetic Skyrmions and Large Topological Hall Effect in Chromium Telluride Engineered by Self-Intercalation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2205967. [PMID: 36245330 DOI: 10.1002/adma.202205967] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/06/2022] [Indexed: 06/16/2023]
Abstract
Room-temperature magnetic skyrmion materials exhibiting robust topological Hall effect (THE) are crucial for novel nano-spintronic devices. However, such skyrmion-hosting materials are rare in nature. In this study, a self-intercalated transition metal dichalcogenide Cr1+ x Te2 with a layered crystal structure that hosts room-temperature skyrmions and exhibits large THE is reported. By tuning the self-intercalate concentration, a monotonic control of Curie temperature from 169 to 333 K and a magnetic anisotropy transition from out-of-plane to the in-plane configuration are achieved. Based on the intercalation engineering, room-temperature skyrmions are successfully created in Cr1.53 Te2 with a Curie temperature of 295 K and a relatively weak perpendicular magnetic anisotropy. Remarkably, a skyrmion-induced topological Hall resistivity as large as ≈106 nΩ cm is observed at 290 K. Moreover, a sign reversal of THE is also found at low temperatures, which can be ascribed to other topological spin textures having an opposite topological charge to that of the skyrmions. Therefore, chromium telluride can be a new paradigm of the skyrmion material family with promising prospects for future device applications.
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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
| | - Junwei Zhang
- School of Materials and Energy and Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou, 730000, China
| | - Youyou Yuan
- Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Yan Wen
- 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
| | - Dongxing Zheng
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Qiang Zhang
- Core Technology Platforms, New York University Abu Dhabi, Abu Dhabi, 129188, United Arab Emirates
| | - 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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7
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Zhao X, Tang J, Pei K, Wang W, Lin SZ, Du H, Tian M, Che R. Current-Induced Magnetic Skyrmions with Controllable Polarities in the Helical Phase. NANO LETTERS 2022; 22:8793-8800. [PMID: 36331209 DOI: 10.1021/acs.nanolett.2c02061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We report the current-induced creation of magnetic skyrmions in a chiral magnet FeGe nanostructure by using in situ Lorentz transmission electron microscopy. We show that magnetic skyrmions with controllable polarity can be transferred from the helical ground state simply by controlling the direction of the current flow at zero magnetic fields. The force analysis and symmetry consideration, backed up by micromagnetic simulations, well explain the experimental results, where magnetic skyrmions are created because of the edge instability of the helical state in the presence of spin-transfer torque. The on-demand generation of skyrmions and control of their polarity by electric current without the need for a magnetic field will enable novel purely electric-controlled skyrmion devices.
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Affiliation(s)
- Xuebing Zhao
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
| | - Jin Tang
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Ke Pei
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
| | - Weiwei Wang
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
| | - Shi-Zeng Lin
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Haifeng Du
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Mingliang Tian
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei230601, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei230031, China
| | - Renchao Che
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai200438, China
- Zhejiang Laboratory, Hangzhou311100, China
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8
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Tai L, Dai B, Li J, Huang H, Chong SK, Wong KL, Zhang H, Zhang P, Deng P, Eckberg C, Qiu G, He H, Wu D, Xu S, Davydov A, Wu R, Wang KL. Distinguishing the Two-Component Anomalous Hall Effect from the Topological Hall Effect. ACS NANO 2022; 16:17336-17346. [PMID: 36126321 DOI: 10.1021/acsnano.2c08155] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In transport, the topological Hall effect (THE) presents itself as nonmonotonic features (or humps and dips) in the Hall signal and is widely interpreted as a sign of chiral spin textures, like magnetic skyrmions. However, when the anomalous Hall effect (AHE) is also present, the coexistence of two AHEs could give rise to similar artifacts, making it difficult to distinguish between genuine THE with AHE and two-component AHE. Here, we confirm genuine THE with AHE by means of transport and magneto-optical Kerr effect (MOKE) microscopy, in which magnetic skyrmions are directly observed, and find that genuine THE occurs in the transition region of the AHE. In sharp contrast, the artifact "THE" or two-component AHE occurs well beyond the saturation of the "AHE component" (under the false assumption of THE + AHE). Furthermore, we distinguish artifact "THE" from genuine THE by three methods: (1) minor loops, (2) temperature dependence, and (3) gate dependence. Minor loops of genuine THE with AHE are always within the full loop, while minor loops of the artifact "THE" may reveal a single loop that cannot fit into the "AHE component". In addition, the temperature or gate dependence of the artifact "THE" may also be accompanied by a polarity change of the "AHE component", as the nonmonotonic features vanish, while the temperature dependence of genuine THE with AHE reveals no such change. Our work may help future researchers to exercise caution and use these methods for careful examination in order to ascertain the genuine THE.
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Affiliation(s)
- Lixuan Tai
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Bingqian Dai
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Jie Li
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | - Hanshen Huang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Su Kong Chong
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Kin L Wong
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Huairuo Zhang
- Theiss Research, Inc., La Jolla, California 92037, United States
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Peng Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Christopher Eckberg
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
- Fibertek, Inc., Herndon, Virginia 20171, United States
- US Army Research Laboratory, Adelphi, Maryland 20783, United States
- US Army Research Laboratory, Playa Vista, California 90094, United States
| | - Gang Qiu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Haoran He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Di Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Shijie Xu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
- Shanghai Key Laboratory of Special Artificial Microstructure and Pohl Institute of Solid State Physics and School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Albert Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
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9
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Magnonic Activity of Circularly Magnetized Ferromagnetic Nanotubes Induced by Dzyalonshinskii-Moriya Interaction. Symmetry (Basel) 2022. [DOI: 10.3390/sym14091771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Magnonic activity, a chiral effect in magnetization dynamics, was recently reported in ferromagnetic nanotubes. Being a perfect analogy to the optical activity, it refers to the continuous rotation of a standing-waves pattern formed in the circumferential direction during the wave propagation along the tube. This effect only occurs when the tube is longitudinally magnetized. Here we report that a similar phenomenon can also take place in circularly magnetized nanotubes with the presence of Dzyalonshinskii-Moriya interaction (DMI). While in the former case, the chiral-symmetry breaking is caused by the curvilinear shape of the tube, it is attributed to the intrinsic asymmetry of the DMI in the latter one. We present the results obtained in both numerical simulations and semi-analytical calculations, which are in great agreement. This work provides new aspects for the manipulation of spin waves, which may bear potential applications in the development of novel spintronic devices.
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10
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Chen G, Ophus C, Lo Conte R, Wiesendanger R, Yin G, Schmid AK, Liu K. Ultrasensitive Sub-monolayer Palladium Induced Chirality Switching and Topological Evolution of Skyrmions. NANO LETTERS 2022; 22:6678-6684. [PMID: 35939526 DOI: 10.1021/acs.nanolett.2c02043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chiral spin textures are fundamentally interesting, with promise for device applications. Stabilizing chirality is conventionally achieved by introducing Dzyaloshinskii-Moriya interaction (DMI) in asymmetric multilayers, where the thickness of each layer is at least a few monolayers. Here we report an ultrasensitive chirality switching in (Ni/Co)n multilayer induced by capping with only 0.22 monolayer of Pd. Using spin-polarized low-energy electron microscopy, we monitor the gradual evolution of domain walls from left-handed to right-handed Néel walls and quantify the DMI induced by the Pd capping layer. We also observe the chiral evolution of a skyrmion during the DMI switching, where no significant topological protection is found as the skyrmion winding number varies. This corresponds to a minimum energy cost of <1 attojoule during the skyrmion chirality switching. Our results demonstrate the detailed chirality evolution within skyrmions during the DMI sign switching, which is relevant to practical applications of skyrmionic devices.
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Affiliation(s)
- Gong Chen
- Department of Physics, Georgetown University, Washington, D.C. 20057, United States
| | - Colin Ophus
- NCEM, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Roberto Lo Conte
- Department of Materials Science & Engineering, University of California, Berkeley, California 95720, United States
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
| | | | - Gen Yin
- Department of Physics, Georgetown University, Washington, D.C. 20057, United States
| | - Andreas K Schmid
- NCEM, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Kai Liu
- Department of Physics, Georgetown University, Washington, D.C. 20057, United States
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11
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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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12
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Jeon JH, Na HR, Kim H, Lee S, Song S, Kim J, Park S, Kim J, Noh H, Kim G, Jerng SK, Chun SH. Emergent Topological Hall Effect from Exchange Coupling in Ferromagnetic Cr 2Te 3/Noncoplanar Antiferromagnetic Cr 2Se 3 Bilayers. ACS NANO 2022; 16:8974-8982. [PMID: 35621270 DOI: 10.1021/acsnano.2c00025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The topological Hall effect has been observed in magnetic materials of complex spin structures or bilayers of trivial magnets and strong spin-orbit-coupled systems. In view of current attention on dissipationless topological electronics, the occurrence of the topological Hall effect in new systems or by an unexpected mechanism is fascinating. Here, we report a robust topological Hall effect generated in bilayers of a ferromagnet and a noncoplanar antiferromagnet, from the interfacial Dzyaloshinskii-Moriya interaction due to the exchange coupling of magnetic layers. Molecular beam epitaxy has been utilized to fabricate heterostructures of a ferromagnetic metal Cr2Te3 and a noncoplanar antiferromagnet Cr2Se3. A significant topological Hall effect at low temperature implies the development of nontrivial spin chirality, and density functional theory calculations explain the correlation of the Dzyaloshinskii-Moriya interaction increase and inversion symmetry breaking at the interface. The presence of noncoplanar ordering in the antiferromagnet plays a pivotal role in producing the topological Hall effect. Our results suggest that the exchange coupling in ferromagnet/noncoplanar antiferromagnet bilayers could be an alternative mechanism toward topologically protected magnetic structures.
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Affiliation(s)
- Jae Ho Jeon
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Hong Ryeol Na
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Heeju Kim
- Department of Physics and HMC, Sejong University, Seoul 05006, Korea
| | - Sunghun Lee
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Sehwan Song
- Department of Physics, Pusan National University, Busan 46241, Korea
| | - Jiwoong Kim
- Department of Physics, Pusan National University, Busan 46241, Korea
| | - Sungkyun Park
- Department of Physics, Pusan National University, Busan 46241, Korea
| | - Jeong Kim
- Department of Electrical Engineering, Sejong University, Seoul 05006, Korea
| | - Hwayong Noh
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Gunn Kim
- Department of Physics and HMC, Sejong University, Seoul 05006, Korea
| | | | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul 05006, Korea
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13
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Liu L, Chen W, Zheng Y. Flexoresponses of Synthetic Antiferromagnetic Systems Hosting Skyrmions. PHYSICAL REVIEW LETTERS 2022; 128:257201. [PMID: 35802441 DOI: 10.1103/physrevlett.128.257201] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
While strain gradients break lattice centrosymmetry, ferromagnetism is a time-reversal symmetry breaking product. Flexomagnetic effect in ferromagnets is usually indirect and weak. In this Letter, we reveal a topologically enhanced flexomagnetic effect in synthetic antiferromagnetic systems based on Dzyaloshinskii-Moriya interaction and the large deformability of skyrmion. Moreover, the synthetic antiferromagnetic skyrmion exhibits an unexpected Hall effect under strain gradient. We propose that this flexo-Hall effect originates from a geometric Magnus force related to the asymmetric deformation of skyrmion. Our results shed new insights into the flexoresponses in systems hosting topological structures and may open up a new field-"flexoskyrmionics".
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Affiliation(s)
- Linjie Liu
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
- Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
| | - Weijin Chen
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
- Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
- School of Materials, Sun Yat-sen University, 518107 Shenzhen, China
| | - Yue Zheng
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
- Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, 510275 Guangzhou, China
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14
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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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15
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Magnonic Metamaterials for Spin-Wave Control with Inhomogeneous Dzyaloshinskii-Moriya Interactions. NANOMATERIALS 2022; 12:nano12071159. [PMID: 35407277 PMCID: PMC9000796 DOI: 10.3390/nano12071159] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/21/2022] [Accepted: 03/28/2022] [Indexed: 12/04/2022]
Abstract
A magnonic metamaterial in the presence of spatially modulated Dzyaloshinskii-Moriya interaction is theoretically proposed and demonstrated by micromagnetic simulations. By analogy to the fields of photonics, we first establish magnonic Snell's law for spin waves passing through an interface between two media with different dispersion relations due to different Dzyaloshinskii-Moriya interactions. Based on magnonic Snell's law, we find that spin waves can experience total internal reflection. The critical angle of total internal reflection is strongly dependent on the sign and strength of Dzyaloshinskii-Moriya interaction. Furthermore, spin-wave beam fiber and spin-wave lens are designed by utilizing the artificial magnonic metamaterials with inhomogeneous Dzyaloshinskii-Moriya interactions. Our findings open up a rich field of spin waves manipulation for prospective applications in magnonics.
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16
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Wolf D, Schneider S, Rößler UK, Kovács A, Schmidt M, Dunin-Borkowski RE, Büchner B, Rellinghaus B, Lubk A. Unveiling the three-dimensional magnetic texture of skyrmion tubes. NATURE NANOTECHNOLOGY 2022; 17:250-255. [PMID: 34931032 PMCID: PMC8930765 DOI: 10.1038/s41565-021-01031-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 10/12/2021] [Indexed: 05/04/2023]
Abstract
Magnetic skyrmions are stable topological solitons with complex non-coplanar spin structures. Their nanoscopic size and the low electric currents required to control their motion has opened a new field of research, skyrmionics, that aims for the usage of skyrmions as information carriers. Further advances in skyrmionics call for a thorough understanding of their three-dimensional (3D) spin texture, skyrmion-skyrmion interactions and the coupling to surfaces and interfaces, which crucially affect skyrmion stability and mobility. Here, we quantitatively reconstruct the 3D magnetic texture of Bloch skyrmions with sub-10-nanometre resolution using holographic vector-field electron tomography. The reconstructed textures reveal local deviations from a homogeneous Bloch character within the skyrmion tubes, details of the collapse of the skyrmion texture at surfaces and a correlated modulation of the skyrmion tubes in FeGe along their tube axes. Additionally, we confirm the fundamental principles of skyrmion formation through an evaluation of the 3D magnetic energy density across these magnetic solitons.
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Affiliation(s)
- Daniel Wolf
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
| | - Sebastian Schneider
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
- Dresden Center for Nanoanalysis, cfaed, Technische Universität Dresden, Dresden, Germany
| | - Ulrich K Rößler
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany
| | - Marcus Schmidt
- Department Chemical Metal Science, Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany
| | - Bernd Büchner
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany
- Institute of Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Bernd Rellinghaus
- Dresden Center for Nanoanalysis, cfaed, Technische Universität Dresden, Dresden, Germany
| | - Axel Lubk
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany.
- Institute of Solid State and Materials Physics, Technische Universität Dresden, Dresden, Germany.
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany.
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17
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Zhang H, Zhu XY, Xu Y, Gawryluk DJ, Xie W, Ju SL, Shi M, Shiroka T, Zhan QF, Pomjakushina E, Shang T. Giant magnetoresistance and topological Hall effect in the EuGa 4antiferromagnet. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:034005. [PMID: 34666329 DOI: 10.1088/1361-648x/ac3102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
We report on systematic temperature- and magnetic field-dependent studies of the EuGa4binary compound, which crystallizes in a centrosymmetric tetragonal BaAl4-type structure with space groupI4/mmm. The electronic properties of EuGa4single crystals, with an antiferromagnetic (AFM) transition atTN∼ 16.4 K, were characterized via electrical resistivity and magnetization measurements. A giant nonsaturating magnetoresistance was observed at low temperatures, reaching∼7×104% at 2 K in a magnetic field of 9 T. In the AFM state, EuGa4undergoes a series of metamagnetic transitions in an applied magnetic field, clearly manifested in its field-dependent electrical resistivity. BelowTN, in the ∼4-7 T field range, we observe also a clear hump-like anomaly in the Hall resistivity which is part of the anomalous Hall resistivity. We attribute such a hump-like feature to the topological Hall effect, usually occurring in noncentrosymmetric materials known to host topological spin textures (as e.g., magnetic skyrmions). Therefore, the family of materials with a tetragonal BaAl4-type structure, to which EuGa4and EuAl4belong, seems to comprise suitable candidates on which one can study the interplay among correlated-electron phenomena (such as charge-density wave or exotic magnetism) with topological spin textures and topologically nontrivial bands.
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Affiliation(s)
- H Zhang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - X Y Zhu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - Y Xu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | - D J Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - W Xie
- DESY, Notkestraβe 85, D-22607 Hamburg, Germany
| | - S L Ju
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zurich, Switzerland
| | - Q F Zhan
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
| | | | - T Shang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, People's Republic of China
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18
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Wang B, Bagués N, Liu T, Kawakami RK, McComb DW. Extracting weak magnetic contrast from complex background contrast in plan-view FeGe thin films. Ultramicroscopy 2021; 232:113395. [PMID: 34653891 DOI: 10.1016/j.ultramic.2021.113395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/07/2021] [Accepted: 09/20/2021] [Indexed: 11/29/2022]
Abstract
The desire to design and build skyrmion-based devices has led to the need to characterize magnetic textures in thin films of functional materials. This can usually be achieved through the Lorentz transmission electron microscopy (LTEM) and the Lorentz scanning transmission electron microscopy (LSTEM) in thin film cross-section and single crystal specimens. However, direct imaging of the magnetic texture in plan-view samples of thin (< 50 nm) films has proved to be challenging due to the complex "background" contrast associated with the microstructure and defects, as well as contributions from bending of the specimens. Using a mechanically polished 35 nm plan-view FeGe thin film, we have explored three methods to extract magnetic contrast from the complex background contrast observed; (1) background subtraction in defocused LTEM images, (2) frequency filtered CoM-DPC reconstructed from LSTEM datasets and 3) registration of 4D-STEM datasets acquired at different tilt angles. Using these methods, we have successfully implemented real space imaging of both the helical phase and skyrmion phase. The ability to understand nanoscale magnetic behavior from plan-view thin films is a fundamental step towards development of highly integrated spin electronics.
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Affiliation(s)
- Binbin Wang
- Department of Materials Science and Engineering, The Ohio State University, OH 43210, United States; Center for Electron Microscopy and Analysis, The Ohio State University, OH 43212, United States.
| | - Núria Bagués
- Center for Electron Microscopy and Analysis, The Ohio State University, OH 43212, United States
| | - Tao Liu
- Department of Physics, The Ohio State University, OH 43212, United States
| | - Roland K Kawakami
- Department of Physics, The Ohio State University, OH 43212, United States
| | - David W McComb
- Department of Materials Science and Engineering, The Ohio State University, OH 43210, United States; Center for Electron Microscopy and Analysis, The Ohio State University, OH 43212, United States.
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19
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Kúkoľová A, Dimitrievska M, Litvinchuk AP, Ramanandan SP, Tappy N, Menon H, Borg M, Grundler D, Fontcuberta I Morral A. Cubic, hexagonal and tetragonal FeGe x phases ( x = 1, 1.5, 2): Raman spectroscopy and magnetic properties. CrystEngComm 2021; 23:6506-6517. [PMID: 34602862 PMCID: PMC8474057 DOI: 10.1039/d1ce00970b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 08/20/2021] [Indexed: 11/30/2022]
Abstract
There is currently an emerging drive towards computational materials design and fabrication of predicted novel materials. One of the keys to developing appropriate fabrication methods is determination of the composition and phase. Here we explore the FeGe system and establish reference Raman signatures for the distinction between FeGe hexagonal and cubic structures, as well as FeGe2 and Fe2Ge3 phases. The experimental results are substantiated by first principles lattice dynamics calculations as well as by complementary structural characterization such as transmission electron microscopy and X-ray diffraction, along with magnetic measurements.
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Affiliation(s)
- A Kúkoľová
- Laboratory of Semiconductor Materials, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - M Dimitrievska
- Laboratory of Semiconductor Materials, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - A P Litvinchuk
- Texas Center for Superconductivity at UH, Department of Physics, University of Houston USA
| | - S P Ramanandan
- Laboratory of Semiconductor Materials, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - N Tappy
- Laboratory of Semiconductor Materials, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - H Menon
- Electrical and Information Technology, Lund University Lund Sweden
- NanoLund, Lund University Lund Sweden
| | - M Borg
- Electrical and Information Technology, Lund University Lund Sweden
- NanoLund, Lund University Lund Sweden
| | - D Grundler
- Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- Institute of Electrical and Micro Engineering, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - A Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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20
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Wei W, Tang J, Wu Y, Wang Y, Jiang J, Li J, Soh Y, Xiong Y, Tian M, Du H. Current-Controlled Topological Magnetic Transformations in a Nanostructured Kagome Magnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101610. [PMID: 34224181 DOI: 10.1002/adma.202101610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/14/2021] [Indexed: 06/13/2023]
Abstract
Topological magnetic charge Q is a fundamental parameter that describes the magnetic domains and determines their intriguing electromagnetic properties. The ability to switch Q in a controlled way by electrical methods allows for flexible manipulation of electromagnetic behavior in future spintronic devices. Here, the room-temperature current-controlled topological magnetic transformations between Q = -1 skyrmions and Q = 0 stripes or type-II bubbles in a kagome crystal Fe3 Sn2 are reported. It is shown that reproducible and reversible skyrmion-bubble and skyrmion-stripe transformations can be achieved by tuning the density of nanosecond pulsed current of the order of ≈1010 A m-2 . Further numerical simulations suggest that spin-transfer torque combined with Joule thermal heating effects determine the current-induced topological magnetic transformations.
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Affiliation(s)
- Wensen Wei
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jin Tang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Key Laboratory for Photoelectric Detection Science and Technology of Education Department of Anhui Province, and School of Physics and Materials Engineering, Hefei Normal University, Hefei, 230601, China
| | - Yihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jialiang Jiang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Junbo Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Yona Soh
- Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- School of Physics and Materials Science, Anhui University, Hefei, 230601, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei, 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
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21
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Bera S, Mandal SS. Skyrmions at vanishingly small Dzyaloshinskii-Moriya interaction or zero magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:255801. [PMID: 33848984 DOI: 10.1088/1361-648x/abf783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
By introducing biquadratic together with usual bilinear ferromagnetic nearest neighbor exchange interaction in a square lattice, we find that the energy of the spin-wave mode is minimized at a finite wavevector for a vanishingly small Dzyaloshinskii-Moriya interaction (DMI), supporting a ground state with spin-spiral structure whose pitch length is unusually short as found in some of the experiments. Apart from reproducing the magnetic structures that can be obtained in a canonical model with nearest neighbor exchange interaction only, a numerical simulation of this model with further introduction of magnetic anisotropy and magnetic field predicts many other magnetic structures some of which are already observed in the experiments. Among many observed structures, nanoscale skyrmion even at vanishingly small DMI is found for the first time in a model. The model provides the nanoscale skyrmions of unit topological charge at zero magnetic field as well. We obtain phase diagrams for all the magnetic structures predicted in the model.
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Affiliation(s)
- Sandip Bera
- Department of Physics, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
| | - Sudhansu S Mandal
- Department of Physics, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
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22
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Xu Y, Das L, Ma JZ, Yi CJ, Nie SM, Shi YG, Tiwari A, Tsirkin SS, Neupert T, Medarde M, Shi M, Chang J, Shang T. Unconventional Transverse Transport above and below the Magnetic Transition Temperature in Weyl Semimetal EuCd_{2}As_{2}. PHYSICAL REVIEW LETTERS 2021; 126:076602. [PMID: 33666464 DOI: 10.1103/physrevlett.126.076602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 11/13/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd_{2}As_{2}. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd_{2}As_{2}, indicating the existence of significant Berry curvature. EuCd_{2}As_{2} represents a rare case in which this unconventional transverse transport emerges both above and below the magnetic transition temperature in the same material. The transport properties evolve with temperature and field in the antiferromagnetic phase in a different manner than in the paramagnetic phase, suggesting different mechanisms to their origin. Our results indicate EuCd_{2}As_{2} is a fertile playground for investigating the interplay between magnetism and topology, and potentially a plethora of topologically nontrivial phases rooted in this interplay.
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Affiliation(s)
- Y Xu
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - L Das
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - J Z Ma
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - C J Yi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - S M Nie
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94035, USA
| | - Y G Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - A Tiwari
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - S S Tsirkin
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - T Neupert
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - M Medarde
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, Villigen CH-5232, Switzerland
| | - J Chang
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - T Shang
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
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Spin Hamiltonians in Magnets: Theories and Computations. Molecules 2021; 26:molecules26040803. [PMID: 33557181 PMCID: PMC7913993 DOI: 10.3390/molecules26040803] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 11/16/2022] Open
Abstract
The effective spin Hamiltonian method has drawn considerable attention for its power to explain and predict magnetic properties in various intriguing materials. In this review, we summarize different types of interactions between spins (hereafter, spin interactions, for short) that may be used in effective spin Hamiltonians as well as the various methods of computing the interaction parameters. A detailed discussion about the merits and possible pitfalls of each technique of computing interaction parameters is provided.
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24
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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: 26] [Impact Index Per Article: 8.7] [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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25
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Wang W, Zhao YF, Wang F, Daniels MW, Chang CZ, Zang J, Xiao D, Wu W. Chiral-Bubble-Induced Topological Hall Effect in Ferromagnetic Topological Insulator Heterostructures. NANO LETTERS 2021; 21:1108-1114. [PMID: 33404255 PMCID: PMC8276525 DOI: 10.1021/acs.nanolett.0c04567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report compelling evidence of an emergent topological Hall effect (THE) from chiral bubbles in a two-dimensional uniaxial ferromagnet, V-doped Sb2Te3 heterostructure. The sign of THE signal is determined by the net curvature of domain walls in different domain configurations, and the strength of THE signal is correlated with the density of nucleation or pinned bubble domains. The experimental results are in good agreement with the integrated linear transport and Monte Carlo simulations, corroborating the emergent gauge field at chiral magnetic bubbles. Our findings not only reveal a general mechanism of THE in two-dimensional ferromagnets but also pave the way for the creation and manipulation of topological spin textures for spintronic applications.
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Affiliation(s)
- Wenbo Wang
- Department of Physics, University of California, Santa Barbara, CA 93106, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Corresponding author:
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Fei Wang
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Matthew W. Daniels
- Alternative Computing Group, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jiadong Zang
- Department of Physics and Materials Science Program, University of New Hampshire, Durham, NH 03824, USA
| | - Di Xiao
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Weida Wu
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Corresponding author:
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26
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Abstract
In modern computing systems there is the need to utilize a large amount of data in maintaining high efficiency. Limited memory bandwidth, coupled with the performance gap between memory and logic, impacts heavily on algorithms performance, increasing the overall time and energy required for computation. A possible approach to overcome such limitations is Logic-In-Memory (LIM). In this paper, we propose a LIM architecture based on a non-volatile skyrmion-based recetrack memory. The architecture can be used as a memory or can perform advanced logic functions on the stored data, for example searching for the maximum/minimum number. The circuit has been designed and validated using physical simulations for the memory array together with digital design tools for the control logic. The results highlight the small area of the proposed architecture and its good energy efficiency compared with a reference CMOS implementation.
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27
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Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures. Nat Commun 2021; 12:79. [PMID: 33397964 PMCID: PMC7782489 DOI: 10.1038/s41467-020-20349-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 11/27/2020] [Indexed: 11/19/2022] Open
Abstract
The Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications. Berry curvature connects to exotic electronic phases hence it provides important insights to understand quantum materials. Here, the authors report sign change of the anomalous Hall effect resulted from Berry curvature change at the interface of a topological insulator/magnetic topological insulator heterostructure.
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28
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Liu Y, Cai N, Yu X, Xuan S. Nucleation and stability of skyrmions in three-dimensional chiral nanostructures. Sci Rep 2020; 10:21717. [PMID: 33303955 PMCID: PMC7730437 DOI: 10.1038/s41598-020-78838-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 11/25/2020] [Indexed: 11/21/2022] Open
Abstract
We studied the magnetization evolution in three-dimensional chiral nanostructures, including nanotubes and circularly curved thin films, by micromagnetic simulations. We found that in a nanotube skyrmions can be formed by broken of the helical stripes on the left and right sides of the nanotube, and the formation of skyrmions doesn't correspond to any abrupt change of topological number. Skyrmions can exist in a large range of magnetic field, and the thinner nanotube has a larger field range for skyrmion existence. The configuration of a skyrmion in nanotubes is different from the one in thin film. From the outer to the inner circular layer, the size of the skyrmion becomes larger, and the deformation becomes more obvious. In circularly curved magnetic films with fixed arc length, there are three kinds of hysteresis processes are found. For the curved films with a large radius, the magnetization evolution behavior is similar to the case in two-dimensional thin films. For the curved films with a small radius, the skyrmions are created by broken of the helical stripes on the left and right sides of the curved film. For the curved film with a medium radius, no skyrmion is formed in the hysteresis process.
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Affiliation(s)
- Yan Liu
- College of Sciences, Northeastern University, Shenyang, 110819, People's Republic of China.
| | - Na Cai
- College of Sciences, Northeastern University, Shenyang, 110819, People's Republic of China
| | - Xingxing Yu
- College of Sciences, Northeastern University, Shenyang, 110819, People's Republic of China
| | - Shengjie Xuan
- College of Sciences, Northeastern University, Shenyang, 110819, People's Republic of China
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29
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Xie ZK, Li Y, Gong ZZ, Yang X, Li Y, Sun R, Li N, Sun YB, Zhao JJ, Cheng ZH, He W. Characterizing the Magnetic Interfacial Coupling of the Fe/FeGe Heterostructure by Ferromagnetic Resonance. ACS APPLIED MATERIALS & INTERFACES 2020; 12:46908-46913. [PMID: 32965100 DOI: 10.1021/acsami.0c11902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We characterize the magnetic interfacial coupling of the Fe/FeGe heterostructure and its influence on the magnetic damping via ferromagnetic resonance in the temperature range of 200-300 K. When the temperature is below the critical temperature of FeGe, the interfacial coupling rises. The strength of the magnetic interfacial coupling is determined as a function of the temperature and reaches up to 0.194 erg/cm2 at 200 K. Meanwhile, the Gilbert damping of the Fe layer is enhanced from 0.035 at 300 K to 0.050 at 200 K. The enhancement is linearly proportional to the strength of magnetic interfacial coupling. We attribute the enhancement to the interfacial coupling that transfers spin angular momentum from Fe to FeGe via the exchange interaction. Our results reveal that the interfacial coupling is an effective approach to inject spin current into the chiral spin texture.
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Affiliation(s)
- Zong-Kai Xie
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yan Li
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zi-Zhao Gong
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xu Yang
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yang Li
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Rui Sun
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Na Li
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yun-Bing Sun
- Department of Physics, Baotou Normal University, Baotou 014030, P. R. China
| | - Jian-Jun Zhao
- Department of Physics, Baotou Normal University, Baotou 014030, P. R. China
| | - Zhao-Hua Cheng
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Wei He
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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30
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Chen K, Lott D, Philippi-Kobs A, Weigand M, Luo C, Radu F. Observation of compact ferrimagnetic skyrmions in DyCo 3 film. NANOSCALE 2020; 12:18137-18143. [PMID: 32852506 DOI: 10.1039/d0nr02947e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Owing to the experimental discovery of magnetic skyrmions stabilized by the Dzyaloshinskii-Moriya and/or dipolar interactions in thin films, there is a recent upsurge of interest in magnetic skyrmions with antiferromagnetic spins in order to overcome the fundamental limitations inherent with skyrmions in ferromagnetic materials. Here, we report on the observation of compact ferrimagnetic skyrmions for the class of amorphous alloys consisting of 4f rare-earth and 3d transition-metal elements with perpendicular magnetic anisotropy, using a DyCo3 film, that are identified by combining X-ray magnetic scattering, scanning transmission X-ray microscopy, and Hall transport technique. These skyrmions, with antiparallel aligned Dy and Co magnetic moments and a characteristic core radius of about 40 nm, are formed during the nucleation and annihilation of the magnetic maze-like domain pattern exhibiting a topological Hall effect contribution. Our findings provide a promising route for fundamental research in the field of ferrimagnetic/antiferromagnetic spintronics towards practical applications.
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Affiliation(s)
- K Chen
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
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31
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Wang D, Wei S, Yuan A, Tian F, Cao K, Zhao Q, Zhang Y, Zhou C, Song X, Xue D, Yang S. Machine Learning Magnetic Parameters from Spin Configurations. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000566. [PMID: 32832350 PMCID: PMC7435232 DOI: 10.1002/advs.202000566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 05/29/2020] [Indexed: 05/27/2023]
Abstract
Hamiltonian parameters estimation is crucial in condensed matter physics, but is time- and cost-consuming. High-resolution images provide detailed information of underlying physics, but extracting Hamiltonian parameters from them is difficult due to the huge Hilbert space. Here, a protocol for Hamiltonian parameters estimation from images based on a machine learning (ML) architecture is provided. It consists in learning a mapping between spin configurations and Hamiltonian parameters from a small amount of simulated images, applying the trained ML model to a single unexplored experimental image to estimate its key parameters, and predicting the corresponding materials properties by a physical model. The efficiency of the approach is demonstrated by reproducing the same spin configuration as the experimental one and predicting the coercive field, the saturation field, and even the volume of the experiment specimen accurately. The proposed approach paves a way to achieve a stable and efficient parameters estimation.
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Affiliation(s)
- Dingchen Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Songrui Wei
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Optoelectronic EngineeringShenzhen UniversityShenzhen518060China
| | - Anran Yuan
- Key Laboratory of Intelligent Perception and Image Understanding of Ministry of EducationInternational Research Center for Intelligent Perception and ComputationJoint International Research Laboratory of Intelligent Perception and ComputationSchool of Artificial IntelligenceXidian UniversityXi'an710071China
| | - Fanghua Tian
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Kaiyan Cao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Qizhong Zhao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Yin Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Chao Zhou
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Xiaoping Song
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Dezhen Xue
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Sen Yang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterSchool of ScienceState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
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Khadka D, Thapaliya TR, Hurtado Parra S, Han X, Wen J, Need RF, Khanal P, Wang W, Zang J, Kikkawa JM, Wu L, Huang SX. Kondo physics in antiferromagnetic Weyl semimetal Mn 3+x Sn 1-x films. SCIENCE ADVANCES 2020; 6:eabc1977. [PMID: 32923648 PMCID: PMC7455184 DOI: 10.1126/sciadv.abc1977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 07/16/2020] [Indexed: 06/11/2023]
Abstract
Topology and strong electron correlations are crucial ingredients in emerging quantum materials, yet their intersection in experimental systems has been relatively limited to date. Strongly correlated Weyl semimetals, particularly when magnetism is incorporated, offer a unique and fertile platform to explore emergent phenomena in novel topological matter and topological spintronics. The antiferromagnetic Weyl semimetal Mn3Sn exhibits many exotic physical properties such as a large spontaneous Hall effect and has recently attracted intense interest. In this work, we report synthesis of epitaxial Mn3+x Sn1-x films with greatly extended compositional range in comparison with that of bulk samples. As Sn atoms are replaced by magnetic Mn atoms, the Kondo effect, which is a celebrated example of strong correlations, emerges, develops coherence, and induces a hybridization energy gap. The magnetic doping and gap opening lead to rich extraordinary properties, as exemplified by the prominent DC Hall effects and resonance-enhanced terahertz Faraday rotation.
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Affiliation(s)
- Durga Khadka
- Department of Physics, University of Miami, Coral Gables, FL 33146, USA
| | - T. R. Thapaliya
- Department of Physics, University of Miami, Coral Gables, FL 33146, USA
| | - Sebastian Hurtado Parra
- Department of Physics and Astronomy, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xingyue Han
- Department of Physics and Astronomy, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jiajia Wen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Ryan F. Need
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20878, USA
| | - Pravin Khanal
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - Weigang Wang
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH 03824, USA
- Materials Science Program, University of New Hampshire, Durham, NH 03824, USA
| | - James M. Kikkawa
- Department of Physics and Astronomy, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Liang Wu
- Department of Physics and Astronomy, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - S. X. Huang
- Department of Physics, University of Miami, Coral Gables, FL 33146, USA
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33
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Voinescu R, Tai JSB, Smalyukh II. Hopf Solitons in Helical and Conical Backgrounds of Chiral Magnetic Solids. PHYSICAL REVIEW LETTERS 2020; 125:057201. [PMID: 32794865 DOI: 10.1103/physrevlett.125.057201] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Three-dimensional topological solitons attract a great deal of interest in fields ranging from particle physics to cosmology, but remain experimentally elusive in solid-state magnets. Here we numerically predict magnetic heliknotons, an embodiment of such nonzero-Hopf-index solitons localized in all spatial dimensions while embedded in a helical or conical background of chiral magnets. We describe conditions under which heliknotons emerge as metastable or ground-state localized nonsingular structures with fascinating knots of magnetization field in widely studied materials. We demonstrate magnetic control of three-dimensional spatial positions of such solitons, as well as show how they interact to form moleculelike clusters and possibly even crystalline phases comprising three-dimensional lattices of such solitons with both orientational and positional order. Finally, we discuss both fundamental importance and potential technological utility of magnetic heliknotons.
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Affiliation(s)
- Robert Voinescu
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Jung-Shen B Tai
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Materials Science and Engineering Program, Soft Materials Research Center and Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, USA
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34
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Liu Z, Santos Dias MD, Lounis S. Theoretical investigation of antiferromagnetic skyrmions in a triangular monolayer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:425801. [PMID: 32460267 DOI: 10.1088/1361-648x/ab96ef] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
The chiral spin textures of a two-dimensional (2D) triangular system, where both antiferromagnetic (AF) Heisenberg exchange and chiral Dzyaloshinsky-Moriya interactions co-exist, are investigated numerically with an optimized quantum Monte Carlo method based on mean-field theory. We find that: helical, skyrmionic and vortical AF crystals can be formed when an external magnetic field is applied perpendicular to the 2D monolayer; the sizes of these skyrmions and vortices change abruptly at several critical points of the external magnetic field; each of these AF crystals can be decomposed into three periodical ferromagnetic sublattices. The quantum ingredient implemented into the theoretical framework helps to track the existence of AF skyrmion lattices down to low temperatures.
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Affiliation(s)
- Zhaosen Liu
- College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, People's Republic of China
| | - Manuel Dos Santos Dias
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
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35
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Chai K, Li ZA, Liu R, Zou B, Farle M, Li J. Dynamics of chiral state transitions and relaxations in an FeGe thin plate via in situ Lorentz microscopy. NANOSCALE 2020; 12:14919-14925. [PMID: 32638795 DOI: 10.1039/d0nr03278f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Studying the magnetic transition between different topological spin textures in noncentrosymmetric magnets under external stimuli is an important topic in chiral magnetism. Here, using in situ Lorentz transmission electron microscopy (LTEM) we directly visualize the thermal-driven magnetic transitions and dynamic characteristics in FeGe thin plates. A novel protocol-dependent phase diagram of FeGe thin plates was obtained via pulsed laser excitation. Moreover, by setting the appropriate specimen temperature, the relaxation of chiral magnetic states in FeGe specimens was recorded and analyzed with an Arrhenius-type relaxation mechanism. We present the field-dependent activation energy barriers for chiral state transitions and the magnetic transition pathways of these spin textures for FeGe thin plates. Our results unveil the effects of thermal excitation on the topological spin texture transitions and provide useful information about magnetic dynamics of chiral magnetic state relaxation.
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Affiliation(s)
- Ke Chai
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing 100081, China. and Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences, Beijing 100190, China
| | - Zi-An Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences, Beijing 100190, China
| | - Ruibin Liu
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing 100081, China.
| | - Bingsuo Zou
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing 100081, China. and Center on Nano-energy Research, School of Physical Science and Technology, Guangxi University, Nanning, 530004, China
| | - Michael Farle
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Jianqi Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences, Beijing 100190, China and Yangtze River Delta Physics Research Center Co., Ltd. - Liyang, Jiangsu, 213300, China and Songshan Lake Materials Laboratory - Dongguan, Guangdong, 523808, China
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36
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Jiang J, Xiao D, Wang F, Shin JH, Andreoli D, Zhang J, Xiao R, Zhao YF, Kayyalha M, Zhang L, Wang K, Zang J, Liu C, Samarth N, Chan MHW, Chang CZ. Concurrence of quantum anomalous Hall and topological Hall effects in magnetic topological insulator sandwich heterostructures. NATURE MATERIALS 2020; 19:732-737. [PMID: 32015537 DOI: 10.1038/s41563-020-0605-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 01/03/2020] [Indexed: 05/08/2023]
Abstract
The quantum anomalous Hall (QAH) effect is a consequence of non-zero Berry curvature in momentum space. The QAH insulator harbours dissipation-free chiral edge states in the absence of an external magnetic field. However, the topological Hall (TH) effect, a hallmark of chiral spin textures, is a consequence of real-space Berry curvature. Here, by inserting a topological insulator (TI) layer between two magnetic TI layers, we realized the concurrence of the TH effect and the QAH effect through electric-field gating. The TH effect is probed by bulk carriers, whereas the QAH effect is characterized by chiral edge states. The appearance of the TH effect in the QAH insulating regime is a consequence of chiral magnetic domain walls that result from the gate-induced Dzyaloshinskii-Moriya interaction and occurs during the magnetization reversal process in the magnetic TI sandwich samples. The coexistence of chiral edge states and chiral spin textures provides a platform for proof-of-concept dissipationless spin-textured spintronic applications.
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Affiliation(s)
- Jue Jiang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Di Xiao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Fei Wang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Jae-Ho Shin
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | | | - Jianxiao Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Run Xiao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Morteza Kayyalha
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Ling Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Jiadong Zang
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Chaoxing Liu
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
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37
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Zhou L, Chen J, Chen X, Xi B, Qiu Y, Zhang J, Wang L, Zhang R, Ye B, Chen P, Zhang X, Guo G, Yu D, Mei JW, Ye F, Wang G, He H. Topological Hall Effect in Traditional Ferromagnet Embedded with Black-Phosphorus-Like Bismuth Nanosheets. ACS APPLIED MATERIALS & INTERFACES 2020; 12:25135-25142. [PMID: 32338493 DOI: 10.1021/acsami.0c04447] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Topological Hall effect is an abnormal Hall response arising from the scalar spin chirality of chiral magnetic textures. Up to now, such an effect is only observed in certain special materials, but rarely in traditional ferromagnets. In this work, we have implemented the molecular beam epitaxy technique to successfully embed black-phosphorus-like bismuth nanosheets with strong spin-orbit coupling into the bulk of chromium telluride Cr2Te3, as evidenced by atomically resolved energy dispersive X-ray spectroscopy mapping. Distinctive from pristine Cr2Te3, these Bi-embedded Cr2Te3 epitaxial films exhibit not only pronounced topological Hall effects, but also magnetoresistivity anomalies and differential magnetic susceptibility plateaus. All these experimental features point to the possible emergence of magnetic skyrmions in Bi-embedded Cr2Te3, which is further supported by our numerical simulations with all input parameters obtained from the first-principle calculations. Therefore, our work demonstrates a new efficient way to induce skyrmions in ferromagnets, as well as the topological Hall effect by embedding nanosheets with strong spin-orbit couplings.
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Affiliation(s)
- Liang Zhou
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Junshu Chen
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Xiaobin Chen
- School of Science, Harbin Institute of Technology, Shenzhen 518055, China
| | - Bin Xi
- College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China
| | - Yang Qiu
- Materials Characterization and Preparation Center, Southern University of Science and Technology, Shenzhen 518055, China
| | - Junwei Zhang
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - Linjing Wang
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Runnan Zhang
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Bicong Ye
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Pingbo Chen
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xixiang Zhang
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - Guoping Guo
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jia-Wei Mei
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Fei Ye
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Gan Wang
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - Hongtao He
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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Budhathoki S, Sapkota A, Law KM, Ranjit S, Nepal B, Hoskins BD, Thind AS, Borisevich AY, Jamer ME, Anderson TJ, Koehler AD, Hobart KD, Stephen GM, Heiman D, Mewes T, Mishra R, Gallagher JC, Hauser AJ. Room Temperature Skyrmions in Strain-Engineered FeGe thin films. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.220405. [PMID: 38487734 PMCID: PMC10938551 DOI: 10.1103/physrevb.101.220405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
Skyrmions hold great promise for low-energy consumption and stable high density information storage, and stabilization of the skyrmion lattice (SkX) phase at or above room temperature is greatly desired for practical use. The topological Hall effect can be used to identify candidate systems above room temperature, a challenging regime for direct observation by Lorentz electron microscopy. Atomically ordered FeGe thin films are grown epitaxially on Ge(111) substrates with ~ 4 % tensile strain. Magnetic characterization reveals enhancement of Curie temperature to 350 K due to strain, well above the bulk value of 278 K. Strong topological Hall effect was observed between 10 K and 330 K, with a significant increase in magnitude observed at 330 K. The increase in magnitude occurs just below the Curie temperature, a similar relative temperature position as the onset of Skx phase in bulk FeGe. The results suggest that strained FeGe films may host a SkX phase above room temperature when significant tensile strain is applied.
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Affiliation(s)
- Sujan Budhathoki
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Arjun Sapkota
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Ka Ming Law
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Smriti Ranjit
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Bhuwan Nepal
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Brian D Hoskins
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A
| | - Arashdeep Singh Thind
- Institute of Materials Science Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
| | - Albina Y Borisevich
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A
| | - Michelle E Jamer
- Physics Department, United States Naval Academy, Annapolis, MD 21402, U.S.A
| | | | | | - Karl D Hobart
- Naval Research Laboratory, Washington, DC 20375, U.S.A
| | - Gregory M Stephen
- Physics Department, Northeastern University, Boston, MA 02115, U.S.A
| | - Don Heiman
- Physics Department, Northeastern University, Boston, MA 02115, U.S.A
| | - Tim Mewes
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
| | - Rohan Mishra
- Institute of Materials Science Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
- Department of Mechanical Engineering Materials Science, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, U.S.A
| | | | - Adam J Hauser
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL 35487, U.S.A
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39
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Wang S, Zeng Q, Liu D, Zhang H, Ma L, Xu G, Liang Y, Zhang Z, Wu H, Che R, Han X, Huang Q. Giant Topological Hall Effect and Superstable Spontaneous Skyrmions below 330 K in a Centrosymmetric Complex Noncollinear Ferromagnet NdMn 2Ge 2. ACS APPLIED MATERIALS & INTERFACES 2020; 12:24125-24132. [PMID: 32363848 DOI: 10.1021/acsami.0c04632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Skyrmions with topologically nontrivial spin textures are promising information carriers in next-generation ultralow power consumption and high-density spintronic devices. To promote their further development and utilization, the search for new room temperature skyrmion-hosting materials is crucial. Considering that most of the previous skyrmion-hosting materials are noncollinear magnets, here, the detection of the topological Hall effect (THE) and the discovery of skyrmions at room temperature are first reported in a centrosymmetric complex noncollinear ferromagnet NdMn2Ge2. Below 330 K, the compound can host stable Bloch-type skyrmions with about 75 nm diameter in a wide window of magnetic field and temperature, including zero magnetic field and room temperature. Moreover, the skyrmions can induce a giant topological Hall effect in a wide temperature range with a maximum value of -2.05 μΩ cm. These features make the compound attractive for both fundamental research and potential application in novel spintronic devices.
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Affiliation(s)
- Shaobo Wang
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Qingwen Zeng
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200438, China
| | - Danmin Liu
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Hongguo Zhang
- Key Laboratory of Advanced Functional Materials, Education Ministry of China, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
| | - Lin Ma
- Key Laboratory of Advanced Functional Materials, Education Ministry of China, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
| | - Guoliang Xu
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Yuntian Liang
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Zhenlu Zhang
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Hui Wu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Renchao Che
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200438, China
| | - Xiaodong Han
- Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Qingzhen Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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40
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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: 59] [Impact Index Per Article: 14.8] [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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41
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Corbett JP, Zhu T, Ahmed AS, Tjung SJ, Repicky JJ, Takeuchi T, Guerrero-Sanchez J, Takeuchi N, Kawakami RK, Gupta JA. Determining Surface Terminations and Chirality of Noncentrosymmetric FeGe Thin Films via Scanning Tunneling Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:9896-9901. [PMID: 31986007 DOI: 10.1021/acsami.9b19724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Scanning tunneling microscopy was used to study the surfaces of 20-100 nm thick FeGe films grown by molecular beam epitaxy. An average surface lattice constant of ∼6.8 Å, in agreement with the bulk value, was observed via scanning tunneling microscopy, low energy electron diffraction, and reflection high energy electron diffraction. Each of the four possible chemical terminations in the FeGe films were identified by comparing atomic-resolution images, showing distinct contrast with simulations from density functional theory calculations. A detailed study of the atomic layering order and registry across step edges allows us to uniquely determine the grain orientation and chirality in these noncentrosymmetric films.
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Affiliation(s)
- Joseph P Corbett
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Tiancong Zhu
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Adam S Ahmed
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Steven J Tjung
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Jacob J Repicky
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Takahiro Takeuchi
- Integrated Graduate School of Medicine, Engineering, and Agricultural Science , University of Yamanashi , Kofu 400-8510 Japan
| | - Jonathan Guerrero-Sanchez
- Centro de Nanociencias y Nanotecnologia , Universidad Nacional Autónoma de México , Apartado Postal 14 , Ensenada , Baja California 22800 , Mexico
| | - Noboru Takeuchi
- Centro de Nanociencias y Nanotecnologia , Universidad Nacional Autónoma de México , Apartado Postal 14 , Ensenada , Baja California 22800 , Mexico
| | - Roland K Kawakami
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Jay A Gupta
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
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42
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Balasubramanian B, Manchanda P, Pahari R, Chen Z, Zhang W, Valloppilly SR, Li X, Sarella A, Yue L, Ullah A, Dev P, Muller DA, Skomski R, Hadjipanayis GC, Sellmyer DJ. Chiral Magnetism and High-Temperature Skyrmions in B20-Ordered Co-Si. PHYSICAL REVIEW LETTERS 2020; 124:057201. [PMID: 32083901 DOI: 10.1103/physrevlett.124.057201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
Magnets with chiral crystal structures and helical spin structures have recently attracted much attention as potential spin-electronics materials, but their relatively low magnetic-ordering temperatures are a disadvantage. While cobalt has long been recognized as an element that promotes high-temperature magnetic ordering, most Co-rich alloys are achiral and exhibit collinear rather than helimagnetic order. Crystallographically, the B20-ordered compound CoSi is an exception due to its chiral structure, but it does not exhibit any kind of magnetic order. Here, we use nonequilibrium processing to produce B20-ordered Co_{1+x}Si_{1-x} with a maximum Co solubility of x=0.043. Above a critical excess-Co content (x_{c}=0.028), the alloys are magnetically ordered, and for x=0.043, a critical temperature T_{c}=328 K is obtained, the highest among all B20-type magnets. The crystal structure of the alloy supports spin spirals caused by Dzyaloshinskii-Moriya interactions, and from magnetic measurements we estimate that the spirals have a periodicity of about 17 nm. Our density-functional calculations explain the combination of high magnetic-ordering temperature and short periodicity in terms of a quantum phase transition where excess-cobalt spins are coupled through the host matrix.
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Affiliation(s)
- Balamurugan Balasubramanian
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Priyanka Manchanda
- Department of Physics and Astronomy, Howard University, Washington, DC 20059, USA
| | - Rabindra Pahari
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Zhen Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Wenyong Zhang
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Shah R Valloppilly
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Xingzhong Li
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Anandakumar Sarella
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Lanping Yue
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Ahsan Ullah
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - Pratibha Dev
- Department of Physics and Astronomy, Howard University, Washington, DC 20059, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Ralph Skomski
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
| | - George C Hadjipanayis
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - David J Sellmyer
- Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA
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43
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Nonlocal accumulation, chemical potential, and Hall effect of skyrmions in Pt/Co/Ir heterostructure. Sci Rep 2020; 10:1009. [PMID: 31974469 PMCID: PMC6978358 DOI: 10.1038/s41598-020-57818-w] [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: 10/09/2019] [Accepted: 01/01/2020] [Indexed: 11/21/2022] Open
Abstract
Magnetic skyrmion is a swirling topological spin texture behaving as an individual particle. It shows a gyro-motion similarly to that of a charged particle under a magnetic field, being led to the transverse shift to the electric current, i.e., skyrmion Hall effect. With the open boundaries of a sample, this results in an accumulation of skyrmions on one side and their depletion on the other side. Here we demonstrate experimentally that this effect propagates non-locally over tens of micrometers even where the electric current is absent, when the narrow wires bridge bar-shaped Pt/Co/Ir heterostructure thin film systems. This nonlocality can be understood in terms of the “chemical potential” gradient for the skyrmion bubble induced by the skyrmion Hall effect in the nonequilibrium steady state under the electric current. The present result shows that the skyrmion Hall effect acts as the skyrmion pump and the thermodynamic concepts can be applied to the aggregate of skyrmion bubbles.
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44
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Cheng Y, Yu S, Zhu M, Hwang J, Yang F. Evidence of the Topological Hall Effect in Pt/Antiferromagnetic Insulator Bilayers. PHYSICAL REVIEW LETTERS 2019; 123:237206. [PMID: 31868464 DOI: 10.1103/physrevlett.123.237206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 11/04/2019] [Indexed: 06/10/2023]
Abstract
The topological Hall effect has been a primary indicator of nontrivial spin textures in magnetic materials. We observe the evidence of the topological Hall effect in Pt/Cr_{2}O_{3} bilayers grown on Al_{2}O_{3}(0001) and Al_{2}O_{3}(112[over ¯]0), where the Cr_{2}O_{3} epitaxial film is an antiferromagnetic insulator. The Pt/Cr_{2}O_{3} bilayers exhibit topological Hall resistivity for Cr_{2}O_{3} thicknesses below 6 nm near and above room temperature, which is above the Néel temperature of Cr_{2}O_{3}, revealing the key role of thermal fluctuations in the formation of spin textures. The similarity of topological Hall signals in (0001)- and (112[over ¯]0)-oriented Cr_{2}O_{3} films indicates that the emergence of spin textures is insensitive to crystalline orientation.
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Affiliation(s)
- Yang Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Sisheng Yu
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Menglin Zhu
- Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43212, USA
| | - Jinwoo Hwang
- Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43212, USA
| | - Fengyuan Yang
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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45
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Wang W, Daniels MW, Liao Z, Zhao Y, Wang J, Koster G, Rijnders G, Chang CZ, Xiao D, Wu W. Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular magnetic anisotropy. NATURE MATERIALS 2019; 18:1054-1059. [PMID: 31406369 DOI: 10.1038/s41563-019-0454-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 07/09/2019] [Indexed: 06/10/2023]
Abstract
Non-coplanar spin textures with scalar spin chirality can generate an effective magnetic field that deflects the motion of charge carriers, resulting in a topological Hall effect (THE)1-3. However, spin chirality fluctuations in two-dimensional ferromagnets with perpendicular magnetic anisotropy have not been considered so far. Here, we report evidence of spin chirality fluctuations by probing the THE above the Curie temperature in two different ferromagnetic ultra-thin films, SrRuO3 and V-doped Sb2Te3. The temperature, magnetic field, thickness and carrier-type dependence of the THE signal, along with Monte Carlo simulations, suggest that spin chirality fluctuations are a common phenomenon in two-dimensional ferromagnets with perpendicular magnetic anisotropy. Our results open a path for exploring spin chirality with topological Hall transport in two-dimensional magnets and beyond4-7.
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Affiliation(s)
- Wenbo Wang
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - Matthew W Daniels
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Zhaoliang Liao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Yifan Zhao
- Department of Physics, Pennsylvania State University, University Park, PA, USA
| | - Jun Wang
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Gertjan Koster
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Guus Rijnders
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands
| | - Cui-Zu Chang
- Department of Physics, Pennsylvania State University, University Park, PA, USA
| | - Di Xiao
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Weida Wu
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA.
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46
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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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47
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Meng KY, Ahmed AS, Baćani M, Mandru AO, Zhao X, Bagués N, Esser BD, Flores J, McComb DW, Hug HJ, Yang F. Observation of Nanoscale Skyrmions in SrIrO 3/SrRuO 3 Bilayers. NANO LETTERS 2019; 19:3169-3175. [PMID: 30935207 DOI: 10.1021/acs.nanolett.9b00596] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Skyrmion imaging and electrical detection via topological Hall (TH) effect are two primary techniques for probing magnetic skyrmions, which hold promise for next-generation magnetic storage. However, these two kinds of complementary techniques have rarely been employed to investigate the same samples. We report the observation of nanoscale skyrmions in SrIrO3/SrRuO3 (SIO/SRO) bilayers in a wide temperature range from 10 to 100 K. The SIO/SRO bilayers exhibit a remarkable TH effect, which is up to 200% larger than the anomalous Hall (AH) effect at 5 K, and zero-field TH effect at 90 K. Using variable-temperature, high-field magnetic force microscopy (MFM), we imaged skyrmions as small as 10 nm, which emerge in the same field ranges as the TH effect. These results reveal a rich space for skyrmion exploration and tunability in oxide heterostructures.
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Affiliation(s)
- Keng-Yuan Meng
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Adam S Ahmed
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Mirko Baćani
- Empa , Swiss Federal Laboratories for Materials Science and Technology , Dübendorf CH-8600 , Switzerland
| | - Andrada-Oana Mandru
- Empa , Swiss Federal Laboratories for Materials Science and Technology , Dübendorf CH-8600 , Switzerland
| | - Xue Zhao
- Empa , Swiss Federal Laboratories for Materials Science and Technology , Dübendorf CH-8600 , Switzerland
| | - Núria Bagués
- Center for Electron Microscopy and Analysis , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Bryan D Esser
- Center for Electron Microscopy and Analysis , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Jose Flores
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
| | - David W McComb
- Center for Electron Microscopy and Analysis , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Hans J Hug
- Empa , Swiss Federal Laboratories for Materials Science and Technology , Dübendorf CH-8600 , Switzerland
- Department of Physics , University of Basel , Basel CH-4056 , Switzerland
| | - Fengyuan Yang
- Department of Physics , The Ohio State University , Columbus , Ohio 43210 , United States
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48
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Schlitz R, Swekis P, Markou A, Reichlova H, Lammel M, Gayles J, Thomas A, Nielsch K, Felser C, Goennenwein STB. All Electrical Access to Topological Transport Features in Mn 1.8PtSn Films. NANO LETTERS 2019; 19:2366-2370. [PMID: 30844284 DOI: 10.1021/acs.nanolett.8b05042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The presence of nontrivial magnetic topology can give rise to nonvanishing scalar spin chirality and consequently a topological Hall or Nernst effect. In turn, topological transport signals can serve as indicators for topological spin structures. This is particularly important in thin films or nanopatterned materials where the spin structure is not readily accessible. Conventionally, the topological response is determined by combining magnetotransport data with an independent magnetometry experiment. This approach is prone to introduce measurement artifacts. In this study, we report the observation of large topological Hall and Nernst effects in micropatterned thin films of Mn1.8PtSn below the spin reorientation temperature TSR ≈ 190 K. The magnitude of the topological Hall effect ρ xyT = 8 nΩm is close to the value reported in bulk Mn2PtSn, and the topological Nernst effect S xyT = 115 nV K-1 measured in the same microstructure has a similar magnitude as reported for bulk MnGe ( S xyT ∼ 150 nV K-1), the only other material where a topological Nernst was reported. We use our data as a model system to introduce a topological quantity, which allows one to detect the presence of topological transport effects without the need for independent magnetometry data. Our approach thus enables the study of topological transport also in nanopatterned materials without detrimental magnetization related limitations.
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Affiliation(s)
- Richard Schlitz
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
| | - Peter Swekis
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Anastasios Markou
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Helena Reichlova
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute of Physics ASCR , v. v. i., Cukrovarnická 10 , 162 53 , Praha 6 , Czech Republic
| | - Michaela Lammel
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
| | - Jacob Gayles
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Andy Thomas
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
| | - Kornelius Nielsch
- Institute for Metallic Materials , Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) , 01069 Dresden , Germany
- Institute of Materials Science , Technische Universität Dresden , 01062 Dresden , Germany
| | - Claudia Felser
- Max-Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Sebastian T B Goennenwein
- Institut für Festkörper- und Materialphysik , Technische Universität Dresden , 01062 Dresden , Germany
- Center for Transport and Devices of Emergent Materials , Technische Universität Dresden , 01062 Dresden , Germany
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49
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Suess D, Vogler C, Bruckner F, Heistracher P, Slanovc F, Abert C. Spin Torque Efficiency and Analytic Error Rate Estimates of Skyrmion Racetrack Memory. Sci Rep 2019; 9:4827. [PMID: 30886184 PMCID: PMC6423329 DOI: 10.1038/s41598-019-41062-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 02/26/2019] [Indexed: 11/16/2022] Open
Abstract
In this paper, the thermal stability of skyrmion bubbles and the critical currents to move them over pinning sites were investigated. For the used pinning geometries and the used parameters, the unexpected behavior is reported that the energy barrier to overcome the pinning site is larger than the energy barrier of the annihilation of a skyrmion. The annihilation takes place at boundaries by current driven motion, as well as due to the excitation over energy barriers, in the absence of currents, without forming Bloch points. It is reported that the pinning sites, which are required to allow thermally stable bits, significantly increase the critical current densities to move the bits in skyrmion-like structures to about jcrit = 0.62 TA/m². The simulation shows that the applied spin transfer model predicts experimentally obtained critical currents to move stable skyrmions at room temperature well, which is in contrast to simulations based on spin orbit torque that predict significantly too low critical currents. By calculating the thermal stability, as well as the critical current, we can derive the spin torque efficiency η = ΔE/Ic = 0.19 kBT300/μA, which is in a similar range to the simulated spin torque efficiency of MRAM structures. Finally, it is shown that the stochastic depinning process of any racetrack-like device requires an extremely narrow depinning time distribution smaller than ~6% of the current pulse length to reach bit error rates smaller than 10-9.
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Affiliation(s)
- Dieter Suess
- Doppler Laboratory, "Advanced Magnetic Sensing and Materials," University of Vienna, Währinger Straße 17, 1090, Vienna, Austria.
| | - Christoph Vogler
- Physics of Functional Materials, University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Florian Bruckner
- Doppler Laboratory, "Advanced Magnetic Sensing and Materials," University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Paul Heistracher
- Doppler Laboratory, "Advanced Magnetic Sensing and Materials," University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Florian Slanovc
- Doppler Laboratory, "Advanced Magnetic Sensing and Materials," University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Class Abert
- Doppler Laboratory, "Advanced Magnetic Sensing and Materials," University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
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50
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Morvan FJ, Luo HB, Yang HX, Zhang X, Zhou Y, Zhao GP, Xia WX, Liu JP. An achiral ferromagnetic/chiral antiferromagnetic bilayer system leading to controllable size and density of skyrmions. Sci Rep 2019; 9:2970. [PMID: 30814603 PMCID: PMC6393523 DOI: 10.1038/s41598-019-39675-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/18/2019] [Indexed: 11/22/2022] Open
Abstract
Magnetic skyrmions are topologically protected domain structures related to the Dzyaloshinskii-Moriya interaction (DMI). To understand how magnetic skyrmions occur under different circumstances, we propose a model for skyrmion formation in a bilayer system of ferromagnetic/antiferromagnetic (FM/AFM) films, in which the bulk DMI is only present in the AFM film. Micromagnetic simulations reveal that skyrmions are formed in this system due to the competition between the DMI and demagnetization energies. A critical interfacial exchange energy (Ai = 6.5 mJ/m2) is determined, above which the competition occurs at its full extent. More skyrmions are formed with increasing external magnetic field till a critical value above which the external field is too large and thus leading to the annihilation of skyrmions. The spacing between two skyrmions can be as small as 45 nm. Our results may give technological implications for future skyrmion applications.
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Affiliation(s)
- F J Morvan
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,University of Chinese Academy of Sciences, 19A Yuquan Rd, Shijingshan District, Beijing, 100049, China
| | - H B Luo
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China. .,Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
| | - H X Yang
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - X Zhang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Y Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - G P Zhao
- College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu, 610068, China
| | - W X Xia
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - J P Liu
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China. .,Department of Physics, University of Texas at Arlington, Arlington, TX, 76019, USA.
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