1
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Yang L, Savchenko AS, Zheng F, Kiselev NS, Rybakov FN, Han X, Blügel S, Dunin-Borkowski RE. Embedded Skyrmion Bags in Thin Films of Chiral Magnets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2403274. [PMID: 39045913 DOI: 10.1002/adma.202403274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 06/25/2024] [Indexed: 07/25/2024]
Abstract
Magnetic skyrmions are topologically nontrivial spin configurations that possess particle-like properties. Earlier research has mainly focused on a specific type of skyrmion with topological charge Q = -1. However, theoretical analyses of 2D chiral magnets have predicted the existence of skyrmion bags-solitons with arbitrary positive or negative topological charge. Although such spin textures are metastable states, recent experimental observations have confirmed the stability of isolated skyrmion bags in a limited range of applied magnetic fields. Here, by utilizing Lorentz transmission electron microscopy, the extraordinary stability of skyrmion bags in thin plates of B20-type FeGe is shown. In particular, it is shown that skyrmion bags embedded within a skyrmion lattice remain stable even in zero or inverted external magnetic fields. A robust protocol for nucleating such embedded skyrmion bags is provided. The results agree perfectly with micromagnetic simulations and establish thin plates of cubic chiral magnets as a powerful platform for exploring a broad spectrum of topological magnetic solitons.
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Affiliation(s)
- Luyan Yang
- Beijing Key Laboratory of Microstructure and Property of Advanced Materials, College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, China
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Andrii S Savchenko
- Peter Grünberg Institute, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Fengshan Zheng
- Spin-X Institute, Center for Electron Microscopy, School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, 511442, China
| | - Nikolai S Kiselev
- Peter Grünberg Institute, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Filipp N Rybakov
- Department of Physics and Astronomy, Uppsala University, Box-516, Uppsala, SE-751 20, Sweden
| | - Xiaodong Han
- Beijing Key Laboratory of Microstructure and Property of Advanced Materials, College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Stefan Blügel
- Peter Grünberg Institute, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425, Jülich, Germany
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2
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Feng X, Yan S, Zhang X, Yin L, Wang H, Wen Y, Yao J, Wang H, Cheng R, Li Z, He J. Spontaneous Skyrmion Bubbles in an Iron-Silicon Alloy with Uniaxial Magnetic Anisotropy. ACS NANO 2024; 18:8475-8483. [PMID: 38456704 DOI: 10.1021/acsnano.4c00658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
The magnetic skyrmions exhibit intriguing topological behaviors, holding promise for future applications in the realm of spintronic devices. Despite recent advancements, achieving spontaneous magnetic skyrmions and topological transitions in magnets featuring uniaxial magnetic anisotropy, particularly at elevated temperatures (>100 K), remains a challenging endeavor. Here, single-crystal Fe5Si3 nanorods with the central symmetry and uniaxial magnetic anisotropy were successfully synthesized on a mica substrate through chemical vapor deposition, which exhibit a high Curie temperature (TC) of about 372 K. The real-time observation, facilitated by Lorentz transmission electron microscopy, revealed the spontaneous formation of magnetic skyrmions and evolution of domains in focused ion beam-prepared Fe5Si3 thin foils. Moreover, Fe5Si3 device transport measurements expose notable magnetoresistance (MR) effects, enabling the interchange between positive and negative MR across specific temperature settings. These results offer various potential avenues for exploring diverse topological spin textures and their formation mechanisms, indicating inventive applications for iron-silicon alloy in the realm of spintronics.
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Affiliation(s)
- Xiaoqiang Feng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Shanshan Yan
- State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, and School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Xiaolin Zhang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Lei Yin
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hao Wang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yao Wen
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jiayi Yao
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hao Wang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Ruiqing Cheng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Hubei Luojia Laboratory, Wuhan 430072, China
| | - Zian Li
- State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, and School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Jun He
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Hubei Luojia Laboratory, Wuhan 430072, China
- Wuhan Institute of Quantum Technology, Wuhan 430206, China
- Institute of Semiconductors, Henan Academy of Sciences, Zhengzhou 450046, China
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3
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Chen Z, Turgut E, Jiang Y, Nguyen KX, Stolt MJ, Jin S, Ralph DC, Fuchs GD, Muller DA. Lorentz electron ptychography for imaging magnetic textures beyond the diffraction limit. NATURE NANOTECHNOLOGY 2022; 17:1165-1170. [PMID: 36316543 DOI: 10.1038/s41565-022-01224-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
Nanoscale spin textures, especially magnetic skyrmions, have attracted intense interest as candidate high-density and power-efficient information carriers for spintronic devices1,2. Facilitating a deeper understanding of sub-hundred-nanometre to atomic-scale spin textures requires more advanced magnetic imaging techniques3-5. Here we demonstrate a Lorentz electron ptychography method that can enable high-resolution, high-sensitivity magnetic field imaging for widely available electron microscopes. The resolution of Lorentz electron ptychography is not limited by the usual diffraction limit of lens optics, but instead is determined by the maximum scattering angle at which a statistically meaningful dose can still be recorded-this can be an improvement of up to 2-6 times depending on the allowable dose. Using FeGe as the model system, we realize a more accurate magnetic field measurement of skyrmions with an improved spatial resolution and sensitivity by also correcting the probe-damping effect from the imaging optics via Lorentz electron ptychography. This allows us to directly resolve subtle internal structures of magnetic skyrmions near the skyrmion cores, boundaries and dislocations in an FeGe single crystal. Our study establishes a quantitative, high-resolution magnetic microscopy technique that can reveal nanoscale spin textures, especially magnetization discontinuities and topological defects in nanomagnets6. The technique's high-dose efficiency should also make it well suited for the exploration of magnetic textures in electron radiation-sensitive materials such as organic or molecular magnets7.
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Affiliation(s)
- Zhen Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- School of Materials Science and Engineering, Tsinghua University, Beijing, China.
| | - Emrah Turgut
- Department of Physics, Oklahoma State University, Stillwater, OK, USA
| | - Yi Jiang
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Kayla X Nguyen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Matthew J Stolt
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Song Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Daniel C Ralph
- Department of Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Gregory D Fuchs
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
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4
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Yao Y, Ding B, Liang J, Li H, Shen X, Yu R, Wang W. Chirality flips of skyrmion bubbles. Nat Commun 2022; 13:5991. [PMID: 36220821 PMCID: PMC9553972 DOI: 10.1038/s41467-022-33700-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 09/28/2022] [Indexed: 11/09/2022] Open
Abstract
The investigation of three-dimensional magnetic textures and chirality switching has attracted enormous interest from the perspective of fundamental research. Here, the three-dimensional magnetic structures of skyrmion bubbles in the centrosymmetric magnet MnNiGa were reconstructed with the vector field tomography approach via Lorentz transmission electron microscopy. The magnetic configuration of the bubbles was determined based on the reconstructed magnetic induction (B-field) at their surfaces and centers. We found that the bubbles easily switched their chirality but preserved their polarity to retain their singularity in the matrix of the material. Our results offer valuable insights into the chirality behavior of skyrmion bubbles.
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Affiliation(s)
- Yuan Yao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Bei Ding
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jinjing Liang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xi Shen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Richeng Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenhong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China. .,Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China.
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5
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Twitchett-Harrison AC, Loudon JC, Pepper RA, Birch MT, Fangohr H, Midgley PA, Balakrishnan G, Hatton PD. Confinement of Skyrmions in Nanoscale FeGe Device-like Structures. ACS APPLIED ELECTRONIC MATERIALS 2022; 4:4427-4437. [PMID: 36185075 PMCID: PMC9520970 DOI: 10.1021/acsaelm.2c00692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/28/2022] [Indexed: 06/16/2023]
Abstract
Skyrmion-based devices have been proposed as a promising solution for low-energy data storage. These devices include racetrack or logic structures and require skyrmions to be confined in regions with dimensions comparable to the size of a single skyrmion. Here we examine skyrmions in FeGe device shapes using Lorentz transmission electron microscopy to reveal the consequences of skyrmion confinement in a device-like structure. Dumbbell-shaped elements were created by focused ion beam milling to provide regions where single skyrmions are confined adjacent to areas containing a skyrmion lattice. Simple block shapes of equivalent dimensions were also prepared to allow a direct comparison with skyrmion formation in a less complex, yet still confined, device geometry. The impact of applying a magnetic field and varying the temperature on the formation of skyrmions within the shapes was examined. This revealed that it is not just confinement within a small device structure that controls the position and number of skyrmions but that a complex device geometry changes the skyrmion behavior, including allowing skyrmions to form at lower applied magnetic fields than in simple shapes. The impact of edges in complex shapes is observed to be significant in changing the behavior of the magnetic textures formed. This could allow methods to be developed to control both the position and number of skyrmions within device structures.
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Affiliation(s)
- Alison C. Twitchett-Harrison
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - James C. Loudon
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Ryan A. Pepper
- Faculty
of Engineering and Physical Sciences, University
of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Max T. Birch
- Max
Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
- Department
of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Hans Fangohr
- Faculty
of Engineering and Physical Sciences, University
of Southampton, Southampton SO17 1BJ, United Kingdom
- Max
Planck Institute for Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Paul A. Midgley
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Geetha Balakrishnan
- Department
of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Peter D. Hatton
- Department
of Physics, Durham University, Durham DH1 3LE, United Kingdom
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6
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Jena J, Göbel B, Hirosawa T, Díaz SA, Wolf D, Hinokihara T, Kumar V, Mertig I, Felser C, Lubk A, Loss D, Parkin SSP. Observation of fractional spin textures in a Heusler material. Nat Commun 2022; 13:2348. [PMID: 35487903 PMCID: PMC9054820 DOI: 10.1038/s41467-022-29991-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/11/2022] [Indexed: 11/09/2022] Open
Abstract
Recently a zoology of non-collinear chiral spin textures has been discovered, most of which, such as skyrmions and antiskyrmions, have integer topological charges. Here we report the experimental real-space observation of the formation and stability of fractional antiskyrmions and fractional elliptical skyrmions in a Heusler material. These fractional objects appear, over a wide range of temperature and magnetic field, at the edges of a sample, whose interior is occupied by an array of nano-objects with integer topological charges, in agreement with our simulations. We explore the evolution of these objects in the presence of magnetic fields and show their interconversion to objects with integer topological charges. This means the topological charge can be varied continuously. These fractional spin textures are not just another type of skyrmion, but are essentially a new state of matter that emerges and lives only at the boundary of a magnetic system. The coexistence of both integer and fractionally charged spin textures in the same material makes the Heusler family of compounds unique for the manipulation of the real-space topology of spin textures and thus an exciting platform for spintronic and magnonic applications. Skyrmions and anti-skyrmions are magnetic textures that have garnered much interest due to their stability. Here, Jena et al demonstrate the existence of fractional spin textures at the edges of Heusler alloy sample, which can have continuous variable topological charges.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
| | - Börge Göbel
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle, Germany
| | - Tomoki Hirosawa
- Department of Physics, University of Tokyo, Bunkyo, Tokyo, 113-0033, Japan.,Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland
| | - Sebastián A Díaz
- Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland.,Faculty of Physics, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Daniel Wolf
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany
| | - Taichi Hinokihara
- Department of Physics, University of Tokyo, Bunkyo, Tokyo, 113-0033, Japan.,Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0047, Japan
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Axel Lubk
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany
| | - Daniel Loss
- Department of Physics, University of Basel, Klingelberg Strasse 82, 4056, Basel, Switzerland
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany.
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7
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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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8
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Zhang F, Shang S, Li Y, Fan B, Zhang R, Zhao B, Lu H, Ma C. REMINDER: CrystEngComm - Invitation to submit an article Tunable electromagnetic properties of Ti3C2Tx/rGO foams decorated with NiO particles. CrystEngComm 2022. [DOI: 10.1039/d2ce00823h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ti3C2Tx MXene-based composites are attractive for electromagnetic wave absorption (EMA) materials due to their high conductivity and abundant dipoles on the surface. Nevertheless, the controlled synthesis of MXene foams with...
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9
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Revealing 3D magnetization of thin films with soft X-ray tomography: magnetic singularities and topological charges. Nat Commun 2020; 11:6382. [PMID: 33318487 PMCID: PMC7736288 DOI: 10.1038/s41467-020-20119-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 11/12/2020] [Indexed: 12/15/2022] Open
Abstract
The knowledge of how magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods which are sensitive only to the surface regions or limited in spatial resolution. Here we report a vector tomographic reconstruction based on soft X-ray transmission microscopy and magnetic dichroism data, which has allowed visualizing the three-dimensional magnetization in a ferromagnetic thin film heterostructure. Different non-trivial topological textures have been resolved and the determination of their topological charge has allowed us to identify a Bloch point and a meron-like texture. Our method relies only on experimental data and might be of wide application and interest in 3D nanomagnetism. Although magnetic tomography has been used in the past to determine the 3D magnetization of materials its application to thin films remains challenging. Here the authors reconstruct the magnetization of a thin film, enabling the measurement of topological charges of magnetic singularities.
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10
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Jena J, Göbel B, Kumar V, Mertig I, Felser C, Parkin S. Evolution and competition between chiral spin textures in nanostripes with D 2d symmetry. SCIENCE ADVANCES 2020; 6:6/49/eabc0723. [PMID: 33277247 PMCID: PMC7821896 DOI: 10.1126/sciadv.abc0723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Chiral spin textures are of considerable interest for applications in spintronics. It has recently been shown that magnetic materials with D 2d symmetry can sustain several distinct spin textures. Here, we show, using Lorentz transmission electron microscopy, that single and double chains of antiskyrmions can be generated at room temperature in nanostripes less than 0.5 μm in width formed from the D 2d Heusler compound Mn1.4Pt0.9Pd0.1Sn. Typically, truncated helical spin textures are formed in low magnetic fields, whose edges are terminated by half antiskyrmions. These evolve into chains of antiskyrmions with increasing magnetic field. Single chains of these objects are located in the middle of the nanostripes even when the stripes are much wider than the antiskyrmions. Moreover, the chains can even include elliptical Bloch skyrmions depending on details of the applied magnetic field history. These findings make D 2d materials special and highly interesting for applications such as magnetic racetrack memory storage devices.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Ingrid Mertig
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany
| | - Stuart Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
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11
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Hirosawa T, Díaz SA, Klinovaja J, Loss D. Magnonic Quadrupole Topological Insulator in Antiskyrmion Crystals. PHYSICAL REVIEW LETTERS 2020; 125:207204. [PMID: 33258632 DOI: 10.1103/physrevlett.125.207204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 09/20/2020] [Accepted: 10/15/2020] [Indexed: 06/12/2023]
Abstract
We uncover that antiskyrmion crystals provide an experimentally accessible platform to realize a magnonic quadrupole topological insulator, whose hallmark signatures are robust magnonic corner states. Furthermore, we show that tuning an applied magnetic field can trigger the self-assembly of antiskyrmions carrying a fractional topological charge along the sample edges. Crucially, these fractional antiskyrmions restore the symmetries needed to enforce the emergence of the magnonic corner states. Using the machinery of nested Wilson loops, adapted to magnonic systems supported by noncollinear magnetic textures, we demonstrate the quantization of the bulk quadrupole moment, edge dipole moments, and corner charges.
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Affiliation(s)
- Tomoki Hirosawa
- Department of Physics, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Sebastián A Díaz
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Jelena Klinovaja
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Daniel Loss
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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12
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Pei K, Liu S, Zhang E, Zhao X, Yang L, Ai L, Li Z, Xiu F, Che R. Anomalous Spin Behavior in Fe 3GeTe 2 Driven by Current Pulses. ACS NANO 2020; 14:9512-9520. [PMID: 32538609 DOI: 10.1021/acsnano.0c03269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, 2D ferromagnetic materials have aroused wide interest for their magnetic properties and potential applications in spintronic and topological devices. However, their actual applications have been severely hindered by intricate challenges such as the unclear spin arrangement. In particular, the evolution of spin texture driven by high-density electron current, which is an essential condition for fabricating devices, remains unclear. Herein, the current-pulse-driven spin textures in 2D ferromagnetic material Fe3GeTe2 have been thoroughly investigated by in situ Lorentz transmission electron microscopy. The dynamic experiments reveal that the stripe domain structure in the AB and AC planes can be broken and rearranged by the high-density current. In particular, the density of domain walls can be modulated, which offers an avenue to achieve a high-density domain structure. This phenomenon is attributed to the weak interlayer exchange interaction in 2D metallic ferromagnetic materials and the strong disturbance from the high-density current. Therefore, a bubble domain structure and random magnetization in Fe3GeTe2 can be acquired by synchronous current pulses and magnetic fields. These achievements reveal domain structure transitions driven by the current in 2D metallic magnetic materials and provide references for the practical applications.
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Affiliation(s)
- Ke Pei
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Xuebing Zhao
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Liting Yang
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Renchao Che
- Laboratory of Advanced Materials, Department of Materials Science, Collaborative Innovation Center of Chemistry for Energy Materials(iChEM), Fudan University, Shanghai 200433, China
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13
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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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14
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Nagase T, Komatsu M, So YG, Ishida T, Yoshida H, Kawaguchi Y, Tanaka Y, Saitoh K, Ikarashi N, Kuwahara M, Nagao M. Smectic Liquid-Crystalline Structure of Skyrmions in Chiral Magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) Thin Film. PHYSICAL REVIEW LETTERS 2019; 123:137203. [PMID: 31697552 DOI: 10.1103/physrevlett.123.137203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Indexed: 06/10/2023]
Abstract
The organizing of magnetic skyrmions shows several forms similar to atomic arrays of solid states. Using Lorentz transmission electron microscopy, we report the first direct observation of a stable liquid-crystalline structure of skyrmions in chiral magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) thin film, caused by magnetic anisotropy and chiral surface twist. Elongated skyrmions are oriented and periodically arranged only in the ⟨110⟩ directions, whereas they exhibit short-range order along the ⟨001⟩ directions, indicating a smectic skyrmion state. In addition, skyrmions possess anisotropic interaction with an opposite sign depending on the crystal orientation, in contrast to existing isotropic interaction.
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Affiliation(s)
- T Nagase
- Department of Electrical, Electronic Engineering and Information Engineering, School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - M Komatsu
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Y G So
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - T Ishida
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - H Yoshida
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - Y Kawaguchi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Y Tanaka
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - K Saitoh
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - N Ikarashi
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - M Kuwahara
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - M Nagao
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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15
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Mathur N, Stolt MJ, Niitsu K, Yu X, Shindo D, Tokura Y, Jin S. Electron Holography and Magnetotransport Measurements Reveal Stabilized Magnetic Skyrmions in Fe 1-xCo xSi Nanowires. ACS NANO 2019; 13:7833-7841. [PMID: 31268671 DOI: 10.1021/acsnano.9b02130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Magnetic skyrmions are topological spin textures that have shown promise for future nonvolatile memory devices. Herein, we report on the stability of magnetic skyrmions in alloyed cubic B20 Fe1-xCoxSi nanowires (NWs) determined using off-axis electron holography and magnetotransport measurements. This study presents the real space observation of one-dimensional skyrmion lattice in a NW of Fe1-xCoxSi which shows that the skyrmion phase in a Fe0.75Co0.25Si NW exists at lower applied magnetic fields (200 Oe) with a reduced domain size (28 ± 2 nm) in comparison to bulk and thin film samples. Magnetotransport measurements were used to observe the helimagnetic transition temperature dependence on the cobalt concentration in the Fe1-xCoxSi NWs. Field-dependent magnetoresistance measurements of Fe1-xCoxSi NWs under applied magnetic field parallel to the NW axis and their second derivative plots reveal the critical fields for the magnetic state transition at different temperatures. A representative magnetic phase diagram constructed with the results from transport measurements of a Fe0.81Co0.19Si NW clearly shows expanded stability region for magnetic skyrmions in the Fe1-xCoxSi NWs.
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Affiliation(s)
- Nitish Mathur
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Matthew J Stolt
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Kodai Niitsu
- Center for Emergent Matter Science (CEMS) , RIKEN , Wako 351-0198 , Japan
| | - Xiuzhen Yu
- Center for Emergent Matter Science (CEMS) , RIKEN , Wako 351-0198 , Japan
| | - Daisuke Shindo
- Center for Emergent Matter Science (CEMS) , RIKEN , Wako 351-0198 , Japan
- Institute of Multidisciplinary Research for Advanced Materials , Tohoku University , Sendai 980-8577 , Japan
| | - Yoshinori Tokura
- Center for Emergent Matter Science (CEMS) , RIKEN , Wako 351-0198 , Japan
- Department of Applied Physics , University of Tokyo , Tokyo 113-8656 , Japan
| | - Song Jin
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
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