1
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Zhang Y, Tang J, Wu Y, Shi M, Xu X, Wang S, Tian M, Du H. Stable skyrmion bundles at room temperature and zero magnetic field in a chiral magnet. Nat Commun 2024; 15:3391. [PMID: 38649678 PMCID: PMC11035646 DOI: 10.1038/s41467-024-47730-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Topological spin textures are characterized by magnetic topological charges, Q, which govern their electromagnetic properties. Recent studies have achieved skyrmion bundles with arbitrary integer values of Q, opening possibilities for exploring topological spintronics based on Q. However, the realization of stable skyrmion bundles in chiral magnets at room temperature and zero magnetic field - the prerequisite for realistic device applications - has remained elusive. Here, through the combination of pulsed currents and reversed magnetic fields, we experimentally achieve skyrmion bundles with different integer Q values - reaching a maximum of 24 at above room temperature and zero magnetic field - in the chiral magnet Co8Zn10Mn2. We demonstrate the field-driven annihilation of high-Q bundles and present a phase diagram as a function of temperature and field. Our experimental findings are consistently corroborated by micromagnetic simulations, which reveal the nature of the skyrmion bundle as that of skyrmion tubes encircled by a fractional Hopfion.
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Grants
- This work was supported by the National Key R&D Program of China, Grant No. 2022YFA1403603 (H.D.); the Natural Science Foundation of China, Grants No. 12174396 (J.T.), 12104123 (Y.W.), and 12241406 (H.D.); the National Natural Science Funds for Distinguished Young Scholar, Grant No. 52325105 (H.D.); the Anhui Provincial Natural Science Foundation, Grant No. 2308085Y32 (J.T.); the Natural Science Project of Colleges and Universities in Anhui Province, Grant No. 2022AH030011 (J.T.); the Strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB33030100 (H.D.); CAS Project for Young Scientists in Basic Research, Grant No. YSBR-084 (H.D.); Systematic Fundamental Research Program Leveraging Major Scientific and Technological Infrastructure, Chinese Academy of Sciences, Grant No. JZHKYPT-2021-08 (H.D.);Anhui Province Excellent Young Teacher Training Project Grant No. YQZD2023067 (Y.W.); and the China Postdoctoral Science Foundation Grant No. 2023M743543 (Y.W.).
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Affiliation(s)
- Yongsen Zhang
- Science Island Branch, Graduate School of USTC, Hefei, 230026, China
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jin Tang
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China.
| | - Yaodong Wu
- School of Physics and Materials Engineering, Hefei Normal University, Hefei, 230601, China
| | - Meng Shi
- Science Island Branch, Graduate School of USTC, Hefei, 230026, China
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Xitong Xu
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei, 230601, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China
| | - Haifeng Du
- Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China.
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2
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Lång E, Lång A, Blicher P, Rognes T, Dommersnes PG, Bøe SO. Topology-guided polar ordering of collective cell migration. SCIENCE ADVANCES 2024; 10:eadk4825. [PMID: 38630812 PMCID: PMC11023523 DOI: 10.1126/sciadv.adk4825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 03/13/2024] [Indexed: 04/19/2024]
Abstract
The ability of epithelial monolayers to self-organize into a dynamic polarized state, where cells migrate in a uniform direction, is essential for tissue regeneration, development, and tumor progression. However, the mechanisms governing long-range polar ordering of motility direction in biological tissues remain unclear. Here, we investigate the self-organizing behavior of quiescent epithelial monolayers that transit to a dynamic state with long-range polar order upon growth factor exposure. We demonstrate that the heightened self-propelled activity of monolayer cells leads to formation of vortex-antivortex pairs that undergo sequential annihilation, ultimately driving the spread of long-range polar order throughout the system. A computational model, which treats the monolayer as an active elastic solid, accurately replicates this behavior, and weakening of cell-to-cell interactions impedes vortex-antivortex annihilation and polar ordering. Our findings uncover a mechanism in epithelia, where elastic solid material characteristics, activated self-propulsion, and topology-mediated guidance converge to fuel a highly efficient polar self-ordering activity.
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Affiliation(s)
- Emma Lång
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Anna Lång
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Pernille Blicher
- Department of Medical Biochemistry, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Torbjørn Rognes
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
- Centre for Bioinformatics, Department of Informatics, University of Oslo, Oslo, Norway
| | - Paul Gunnar Dommersnes
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Stig Ove Bøe
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
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3
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Chen G, Zhang R, Yuan M, Xue S, Liu Y, Li B, Luo K, Lai Y, Zhang J, Lv H, Che R. Visualizing Nanoscale Interlayer Magnetic Interactions and Unconventional Low-Frequency Behaviors in Ferromagnetic Multishelled Structures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2313411. [PMID: 38469974 DOI: 10.1002/adma.202313411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 02/28/2024] [Indexed: 03/13/2024]
Abstract
Precise manipulation of van der Waals forces within 2D atomic layers allows for exact control over electron-phonon coupling, leading to the exceptional quantum properties. However, applying this technique to diverse structures such as 3D materials is challenging. Therefore, investigating new hierarchical structures and different interlayer forces is crucial for overcoming these limitations and discovering novel physical properties. In this work, a multishelled ferromagnetic material with controllable shell numbers is developed. By strategically regulating the magnetic interactions between these shells, the magnetic properties of each shell are fine-tuned. This approach reveals distinctive magnetic characteristics including regulated magnetic domain configurations and enhanced effective fields. The nanoscale magnetic interactions between the shells are observed and analyzed, which shed light on the modified magnetic properties of each shell, enhancing the understanding and control of ferromagnetic materials. The distinctive magnetic interaction significantly boosts electromagnetic absorption at low-frequency frequencies used by fifth-generation wireless devices, outperforming ferromagnetic materials without multilayer structures by several folds. The application of magnetic interactions in materials science reveals thrilling prospects for technological and electronic innovation.
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Affiliation(s)
- Guanyu Chen
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
| | - Ruixuan Zhang
- Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, China
- Zhejiang Laboratory, Hangzhou, 311100, P. R. China
| | - Mingyue Yuan
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
| | - Shuyan Xue
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
| | - Yihao Liu
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
| | - Bangxin Li
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200438, China
| | - Kaicheng Luo
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
| | - Yuxiang Lai
- Pico Electron Microscopy Center, Innovation Institute for Ocean Materials Characterization, Center for Advanced Studies in Precision Instruments, Hainan University, Haikou, 570228, China
| | | | - Hualiang Lv
- Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, China
| | - Renchao Che
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Academy for Engineering and Technology, Fudan University, Shanghai, 200438, P. R. China
- Zhejiang Laboratory, Hangzhou, 311100, P. R. China
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4
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Gallardo R, Weigand M, Schultheiss K, Kakay A, Mattheis R, Raabe J, Schütz G, Deac A, Lindner J, Wintz S. Coherent Magnons with Giant Nonreciprocity at Nanoscale Wavelengths. ACS NANO 2024. [PMID: 38314709 PMCID: PMC10883124 DOI: 10.1021/acsnano.3c08390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Nonreciprocal wave propagation arises in systems with broken time-reversal symmetry and is key to the functionality of devices, such as isolators or circulators, in microwave, photonic, and acoustic applications. In magnetic systems, collective wave excitations known as magnon quasiparticles have so far yielded moderate nonreciprocities, mainly observed by means of incoherent thermal magnon spectra, while their occurrence as coherent spin waves (magnon ensembles with identical phase) is yet to be demonstrated. Here, we report the direct observation of strongly nonreciprocal propagating coherent spin waves in a patterned element of a ferromagnetic bilayer stack with antiparallel magnetic orientations. We use time-resolved scanning transmission X-ray microscopy (TR-STXM) to directly image the layer-collective dynamics of spin waves with wavelengths ranging from 5 μm down to 100 nm emergent at frequencies between 500 MHz and 5 GHz. The experimentally observed nonreciprocity factor of these counter-propagating waves is greater than 10 with respect to both group velocities and specific wavelengths. Our experimental findings are supported by the results from an analytic theory, and their peculiarities are further discussed in terms of caustic spin-wave focusing.
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Affiliation(s)
- Rodolfo Gallardo
- Universidad Técnica Federico Santa María, 2390123 Valparaíso, Chile
| | | | - Katrin Schultheiss
- Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany
| | - Attila Kakay
- Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany
| | - Roland Mattheis
- Leibniz Institut für Photonische Technologien, 07745 Jena, Germany
| | - Jörg Raabe
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Gisela Schütz
- Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart, Germany
| | - Alina Deac
- Helmholtz-Zentrum Dresden-Rossendorf, Dresden High Magnetic Field Laboratory, 01328 Dresden, Germany
| | - Jürgen Lindner
- Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany
| | - Sebastian Wintz
- Helmholtz-Zentrum Berlin, 12489 Berlin, Germany
- Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart, Germany
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5
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Kim KM, Go G, Park MJ, Kim SK. Emergence of Stable Meron Quartets in Twisted Magnets. NANO LETTERS 2024; 24:74-81. [PMID: 38148280 DOI: 10.1021/acs.nanolett.3c03246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
The investigation of twist engineering in easy-axis magnetic systems has revealed remarkable potential for generating topological spin textures. Implementing twist engineering in easy-plane magnets, we introduce a novel approach to achieving fractional topological spin textures, such as merons. Through atomistic spin simulations on twisted bilayer magnets, we demonstrate the formation of a stable double Meron pair, which we refer to as the "Meron Quartet" (MQ). Unlike a single pair, the merons within the MQ exhibit exceptional stability against pair annihilation due to the protective localization mechanism induced by the twist that prevents collision of the Meron cores. Furthermore, we showcase that the stability of the MQ can be enhanced by adjusting the twist angle, resulting in an increased resistance to external perturbations such as external magnetic fields. Our findings highlight the twisted magnet as a promising platform for achieving merons as stable magnetic quasiparticles in van der Waals magnets.
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Affiliation(s)
- Kyoung-Min Kim
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34126, Republic of Korea
| | - Gyungchoon Go
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Moon Jip Park
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - Se Kwon Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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6
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Otxoa RM, Tatara G, Roy PE, Chubykalo-Fesenko O. Tailoring elastic and inelastic collisions of relativistic antiferromagnetic domain walls. Sci Rep 2023; 13:21153. [PMID: 38036601 PMCID: PMC10689819 DOI: 10.1038/s41598-023-47662-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/16/2023] [Indexed: 12/02/2023] Open
Abstract
Soliton-based computing relies on their unique properties for transporting energy and emerging intact from head-on collisions. Magnetic domain walls are often referred to as solitons disregarding the strict mathematical definition requiring the above scattering property. Here we demonstrate the conditions of elastic and inelastic scattering for spin-orbit torque-induced dynamics of relativistic domain walls on the technologically relevant Mn[Formula: see text]Au antiferromagnetic material. We show that even domain walls with opposite winding numbers can experience elastic scattering and we present the corresponding phase diagram as a function of the spin-orbit field strength and duration. The elastic collision requires minimum domain walls speed, which we explain assuming an attractive potential created by domain wall pair. On the contrary, when the domain walls move at lower speeds, their collision is inelastic and results in a dispersing breather. Our findings will be important for the development of soliton-based computing using antiferromagnetic spintronics and we discuss their prospects for building NOT and XOR gates.
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Affiliation(s)
- Rubén M Otxoa
- Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge, CB3 OHE, UK.
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastián, Spain.
| | - Gen Tatara
- RIKEN Center for Emergent Matter Science (CEMS) and RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Pierre E Roy
- Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge, CB3 OHE, UK
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7
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Niraula G, Toneto D, Goya GF, Zoppellaro G, Coaquira JAH, Muraca D, Denardin JC, Almeida TP, Knobel M, Ayesh AI, Sharma SK. Observation of magnetic vortex configuration in non-stoichiometric Fe 3O 4 nanospheres. NANOSCALE ADVANCES 2023; 5:5015-5028. [PMID: 37705767 PMCID: PMC10496882 DOI: 10.1039/d3na00433c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/14/2023] [Indexed: 09/15/2023]
Abstract
Theoretical and micromagnetic simulation studies of magnetic nanospheres with vortex configurations suggest that such nanostructured materials have technological advantages over conventional nanosystems for applications based on high-power-rate absorption and subsequent emission. However, full experimental evidence of magnetic vortex configurations in spheres of submicrometer size is still lacking. Here, we report the microwave irradiation fabrication of Fe3O4 nanospheres and establish their magnetic vortex configuration based on experimental results, theoretical analysis, and micromagnetic simulations. Detailed magnetic and electrical measurements, together with Mössbauer spectroscopy data, provide evidence of a loss of stoichiometry in vortex nanospheres owing to the presence of a surface oxide layer, defects, and a higher concentration of cation vacancies. The results indicate that the magnetic vortex spin configuration can be established in bulk spherical magnetite materials. This study provides crucial information that can aid the synthesis of magnetic nanospheres with magnetically tailored properties; consequently, they may be promising candidates for future technological applications based on three-dimensional magnetic vortex structures.
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Affiliation(s)
- Gopal Niraula
- Department of Physics, Federal University of Maranhao Sao Luis 65080-805 Brazil
- Laboratory of Magnetic Materials, NFA, Institute of Physics, University of Brasilia Brasilia 70910-900 Brazil
| | | | - Gerardo F Goya
- Instituto de Nanociencia y Materiales de Aragón (INMA), Universidad de Zaragoza 50018 Zaragoza Spain
| | - Giorgio Zoppellaro
- Regional Centre of Advanced Technologies and Materials, Palacky University in Olomouc Slechtitelu 27 77900 Olomouc Czech Republic
| | - Jose A H Coaquira
- Laboratory of Magnetic Materials, NFA, Institute of Physics, University of Brasilia Brasilia 70910-900 Brazil
| | - Diego Muraca
- Institute of Physics "Gleb Wataghin" (IFGW), University of Campinas (Unicamp) Campinas SP Brazil
| | - Juliano C Denardin
- Universidad de Santiago de Chile (USACH), CEDENNA and Departamento de Física Santiago 9170124 Chile
| | - Trevor P Almeida
- SUPA, School of Physics and Astronomy, University of Glasgow Glasgow G12 8QQ UK
| | - Marcelo Knobel
- Institute of Physics "Gleb Wataghin" (IFGW), University of Campinas (Unicamp) Campinas SP Brazil
| | - Ahmad I Ayesh
- Physics Program, Department of Math., Stat. and Physics, College of Arts and Sciences, Qatar University P. O. Box 2713 Doha Qatar
| | - Surender K Sharma
- Department of Physics, Central University of Punjab Bathinda 151401 India
- Department of Physics, Federal University of Maranhao Sao Luis 65080-805 Brazil
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8
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Hu C, Shen X, Bo L, Zhao R, Zhu D, Ji L, Bai G, Zhang X. Dzyaloshinskii-Moriya-Interaction-Like Behavior in Confined Permalloy Nanostructures via Coupled Magnetic Vortices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2207206. [PMID: 36604999 DOI: 10.1002/smll.202207206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/19/2022] [Indexed: 06/17/2023]
Abstract
Dzyaloshinskii-Moriya interaction (DMI), one of antisymmetric exchanges, originates from the combination of low structural symmetry and large spin-orbit coupling and favors magnetization rotations with fixed chirality. Herein, this work reports a DMI-like behavior in permalloy via coupled vortices in confined structures. Under the in-plane magnetic fields, continuous reversals of different coupled vortices are directly observed by in situ Lorentz transmission electron microscopy, and reproduced by complementary micromagnetic simulations. The statistical results show that coupled vortices with opposite chirality appear more frequently with the frequency up to about 60%. Such an asymmetric phenomenon mainly arises from a DMI-like behavior, associated with the increased total energy difference between different ground-state coupled vortices. Moreover, in the reversal process, the junction between disks accelerates the annihilation of vortices moving toward it and is also the starting point of vortex nucleation. These results provide an effective method to generate a DMI-like behavior in magnetic systems with symmetry breaking surface and benefit the future development of vortex-based spintronic devices.
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Affiliation(s)
- Chenglong Hu
- Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials Science and Engineering, Northeastern University, Shenyang, 110819, P. R. China
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
| | - Xiaochen Shen
- Key Laboratory of Materials Modification by Laser, Iron and Electron Beams, School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116023, P. R. China
| | - Lan Bo
- Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials Science and Engineering, Northeastern University, Shenyang, 110819, P. R. China
| | - Rongzhi Zhao
- Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials Science and Engineering, Northeastern University, Shenyang, 110819, P. R. China
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
| | - Dapeng Zhu
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
| | - Lianze Ji
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
| | - Guohua Bai
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
| | - Xuefeng Zhang
- Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials Science and Engineering, Northeastern University, Shenyang, 110819, P. R. China
- Institute of Advanced Magnetic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310012, P. R. China
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9
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Aldulaimi WAS, Okatan MB, Sendur K, Onbasli MC, Misirlioglu IB. Size driven barrier to chirality reversal in electric control of magnetic vortices in ferromagnetic nanodiscs. NANOSCALE 2023; 15:707-717. [PMID: 36516064 DOI: 10.1039/d2nr02768b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
New high density storage media and spintronic devices come about with a progressing demand for the miniaturization of ferromagnetic structures. Vortex ordering of magnetic dipoles in such structures has been repeatedly observed as a stable state, offering the possibility of chirality in these states as a means to store information at high density. Electric pulses and magnetoelectric coupling are attractive options to control the chirality of such states in a deterministic manner. Here, we demonstrate the chirality reversal of vortex states in ferromagnetic nanodiscs via pulsed electric fields using a micromagnetic approach and focus on the analysis of the energetics of the reversal process. A strong thickness dependence of the chirality reversal in the nanodiscs is found that emanates from the anisotropy of the demagnetizing fields. Our results indicate that chiral switching of the magnetic moments in thin discs can give rise to a transient vortex-antivortex lattice not observed in thicker discs. This difference in the chirality reversal mechanism emanates from profoundly different energy barriers to overcome in thin and thicker discs. We also report the polarity-chirality correlation of a vortex that appears to depend on the aspect ratio of the nanodiscs.
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Affiliation(s)
- W A S Aldulaimi
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
| | - M B Okatan
- Department of Materials Science and Engineering, Izmir Institute of Technology, Gulbahce/Urla, 35430 Izmir, Turkey
| | - K Sendur
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
- Center of Excellence for Functional Surfaces and Interfaces for Nano-Diagnostics (EFSUN), Sabanci University, Orhanli, 34956, Tuzla, Istanbul, Turkey
| | - M C Onbasli
- Department of Electrical & Electronics Engineering, Koc University, 34450 Istanbul, Turkey
| | - I B Misirlioglu
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
- Center of Excellence for Functional Surfaces and Interfaces for Nano-Diagnostics (EFSUN), Sabanci University, Orhanli, 34956, Tuzla, Istanbul, Turkey
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10
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Parente A, Navarro H, Vargas NM, Lapa P, Basaran AC, González EM, Redondo C, Morales R, Munoz Noval A, Schuller IK, Vicent JL. Unusual Magnetic Hysteresis and Transition between Vortex and Double Pole States Arising from Interlayer Coupling in Diamond-Shaped Nanostructures. ACS APPLIED MATERIALS & INTERFACES 2022; 14:54961-54968. [PMID: 36469495 DOI: 10.1021/acsami.2c16950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Controlling the magnetic ground states at the nanoscale is a long-standing basic research problem and an important issue in magnetic storage technologies. Here, we designed a nanostructured material that exhibits very unusual hysteresis loops due to a transition between vortex and double pole states. Arrays of 700 nm diamond-shaped nanodots consisting of Py(30 nm)/Ru(tRu)/Py(30 nm) (Py, permalloy (Ni80Fe20)) trilayers were fabricated by interference lithography and e-beam evaporation. We show that varying the Ru interlayer spacer thickness (tRu) governs the interaction between the Py layers. We found this interaction mainly mediated by two mechanisms: magnetostatic interaction that favors antiparallel (antiferromagnetic, AFM) alignment of the Py layers and exchange interaction that oscillates between ferromagnetic (FM) and AFM couplings. For a certain range of Ru thicknesses, FM coupling dominates and forms magnetic vortices in the upper and lower Py layers. For Ru thicknesses at which AFM coupling dominates, the magnetic state in remanence is a double pole structure. Our results showed that the interlayer exchange coupling interaction remains finite even at 4 nm Ru thickness. The magnetic states in remanence, observed by magnetic force microscopy (MFM), are in good agreement with corresponding hysteresis loops obtained by the magneto-optic Kerr effect (MOKE) and micromagnetic simulations.
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Affiliation(s)
- A Parente
- Departamento de Física de Materiales, Facultad de Física, Universidad Complutense de Madrid, Pl. Ciencias, 1, 28040 Madrid, Spain
| | - H Navarro
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - N M Vargas
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - P Lapa
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - Ali C Basaran
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - E M González
- Departamento de Física de Materiales, Facultad de Física, Universidad Complutense de Madrid, Pl. Ciencias, 1, 28040 Madrid, Spain
- IMDEA Nanociencia, c/ Faraday, 9, 28049 Madrid, Spain
| | - C Redondo
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - R Morales
- Department of Physical Chemistry, University of the Basque Country UPV/EHU & BCMaterials, 48940 Leioa, Spain
- IKERBASQUE. Basque Foundation for Science, 48009 Bilbao, Spain
| | - A Munoz Noval
- Departamento de Física de Materiales, Facultad de Física, Universidad Complutense de Madrid, Pl. Ciencias, 1, 28040 Madrid, Spain
- IMDEA Nanociencia, c/ Faraday, 9, 28049 Madrid, Spain
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, United States
| | - J L Vicent
- Departamento de Física de Materiales, Facultad de Física, Universidad Complutense de Madrid, Pl. Ciencias, 1, 28040 Madrid, Spain
- IMDEA Nanociencia, c/ Faraday, 9, 28049 Madrid, Spain
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11
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Liu H, Sun R, Wang L, Chen X, Li G, Cheng Y, Zhai G, Bay BH, Yang F, Gu N, Guo Y, Fan H. Biocompatible Iron Oxide Nanoring-Labeled Mesenchymal Stem Cells: An Innovative Magnetothermal Approach for Cell Tracking and Targeted Stroke Therapy. ACS NANO 2022; 16:18806-18821. [PMID: 36278899 DOI: 10.1021/acsnano.2c07581] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Labeling stem cells with magnetic nanoparticles is a promising technique for in vivo tracking and magnetic targeting of transplanted stem cells, which is critical for improving the therapeutic efficacy of cell therapy. However, conventional endocytic labeling with relatively poor labeling efficiency and a short labeling lifetime has hindered the implementation of these innovative enhancements in stem-cell-mediated regenerative medicine. Herein, we describe an advanced magnetothermal approach to label mesenchymal stem cells (MSCs) efficiently by local induction of heat-enhanced membrane permeability for magnetic resonance imaging (MRI) tracking and targeted therapy of stroke, where biocompatible γ-phase, ferrimagnetic vortex-domain iron oxide nanorings (γ-FVIOs) with superior magnetoresponsive properties were used as a tracer. This approach facilitates a safe and efficient labeling of γ-FVIOs as high as 150 pg of Fe per cell without affecting the MSCs proliferation and differentiation, which is 3.44-fold higher than that by endocytosis labeling. Such a high labeling efficiency not only enables the ultrasensitive magnetic resonance imaging (MRI) detection of sub-10 cells and long-term tracking of transplanted MSCs over 10 weeks but also endows transplanted MSCs with a magnetic manipulation ability in vivo. A proof-of-concept study using a rat stroke model showed that the labeled MSCs facilitated MRI tracking and magnetic targeting for efficient replacement therapy with a significantly reduced dosage of 5 × 104 transplanted cells. The findings in this study have demonstrated the great potential of the magnetothermal approach as an efficient labeling technique for future clinical usage.
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Affiliation(s)
- Hanrui Liu
- Development and Related Diseases of Women and Children Key Laboratory of Sichuan Province, West China Second University Hospital, Sichuan University, Chengdu610041, China
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an710127, China
| | - Ran Sun
- Development and Related Diseases of Women and Children Key Laboratory of Sichuan Province, West China Second University Hospital, Sichuan University, Chengdu610041, China
| | - Lei Wang
- Molecular Imaging Center, West China Hospital, Sichuan University, Chengdu610041, China
| | - Xiaoyong Chen
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an710127, China
| | - Galong Li
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an710127, China
- School of Medicine, Northwest University, Xi'an710069, China
| | - Yu Cheng
- Institute for Regenerative Medicine, The Institute for Biomedical Engineering & Nano Science, Shanghai East Hospital, Tongji University School of Medicine, 1800 Yuntai Road, Shanghai200092, China
| | - Gaohong Zhai
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an710127, China
| | - Boon-Huat Bay
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, 4 Medical Drive, MD10, 117594, Singapore
| | - Fang Yang
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing210009, China
| | - Ning Gu
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing210009, China
| | - Yingkun Guo
- Development and Related Diseases of Women and Children Key Laboratory of Sichuan Province, West China Second University Hospital, Sichuan University, Chengdu610041, China
| | - Haiming Fan
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an710127, China
- School of Medicine, Northwest University, Xi'an710069, China
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12
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Singh B, Ravishankar R, Otálora JA, Soldatov I, Schäfer R, Karnaushenko D, Neu V, Schmidt OG. Direct imaging of nanoscale field-driven domain wall oscillations in Landau structures. NANOSCALE 2022; 14:13667-13678. [PMID: 36082910 DOI: 10.1039/d2nr03351h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Linear oscillatory motion of domain walls (DWs) in the kHz and MHz regime is crucial when realizing precise magnetic field sensors such as giant magnetoimpedance devices. Numerous magnetically active defects lead to pinning of the DWs during their motion, affecting the overall behavior. Thus, the direct monitoring of the domain wall's oscillatory behavior is an important step to comprehend the underlying micromagnetic processes and to improve the magnetoresistive performance of these devices. Here, we report an imaging approach to investigate such DW dynamics with nanoscale spatial resolution employing conventional table-top microscopy techniques. Time-averaged magnetic force microscopy and Kerr imaging methods are applied to quantify the DW oscillations in Ni81Fe19 rectangular structures with Landau domain configuration and are complemented by numeric micromagnetic simulations. We study the oscillation amplitude as a function of external magnetic field strength, frequency, magnetic structure size, thickness and anisotropy and understand the excited DW behavior as a forced damped harmonic oscillator with restoring force being influenced by the geometry, thickness, and anisotropy of the Ni81Fe19 structure. This approach offers new possibilities for the analysis of DW motion at elevated frequencies and at a spatial resolution of well below 100 nm in various branches of nanomagnetism.
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Affiliation(s)
- Balram Singh
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069 Dresden, Germany.
- Nanophysics, Faculty of Physics, TU Dresden, 01062 Dresden, Germany
| | - Rachappa Ravishankar
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069 Dresden, Germany.
| | - Jorge A Otálora
- Departamento de Física, Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280, Antofagasta, Chile
| | - Ivan Soldatov
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069 Dresden, Germany.
| | - Rudolf Schäfer
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069 Dresden, Germany.
- Institute for Materials Science, TU Dresden, 01062 Dresden, Germany
| | - Daniil Karnaushenko
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126 Chemnitz, Germany.
| | - Volker Neu
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069 Dresden, Germany.
| | - Oliver G Schmidt
- Nanophysics, Faculty of Physics, TU Dresden, 01062 Dresden, Germany
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126 Chemnitz, Germany.
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107 Chemnitz, Germany
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13
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TimeMaxyne: A Shot-Noise Limited, Time-Resolved Pump-and-Probe Acquisition System Capable of 50 GHz Frequencies for Synchrotron-Based X-ray Microscopy. CRYSTALS 2022. [DOI: 10.3390/cryst12081029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
With the advent of modern synchrotron sources, X-ray microscopy was developed as a vigorous tool for imaging material structures with element-specific, structural, chemical and magnetic sensitivity at resolutions down to 25 nm and below. Moreover, the X-ray time structure emitted from the synchrotron source (short bunches of less than 100 ps width) provides a unique possibility to combine high spatial resolution with high temporal resolution for periodic processes by means of pump-and-probe measurements. To that end, TimeMaxyne was developed as a time-resolved acquisition setup for the scanning X-ray microscope MAXYMUS at the BESSY II synchrotron in order to perform high precision, high throughput pump-and-probe imaging. The setup combines a highly sensitive single photon detector, a real time photon sorting system and a dedicated synchronization scheme for aligning various types of sample excitations of up to 50 GHz bandwidth to the photon probe. Hence, TimeMaxyne has been demonstrated to be capable of shot-noise limited, time-resolved imaging, at time resolutions of 50 ps and below, only limited by the X-ray pulse widths of the synchrotron.
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14
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Lu X, Zhu L, Yang L. Multi-meron interactions and statistics in two-dimensional materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:275802. [PMID: 35417893 DOI: 10.1088/1361-648x/ac671c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
As a fundamental type of topological spin textures in two-dimensional (2D) magnets, a magnetic meron carries half-integer topological charge and forms a pair with its antithesis to keep the stability in materials. However, it is challenging to quantitatively calculate merons and their dynamics by using the widely used continuum model because of the characteristic highly inhomogeneous spin textures. In this work, we develop a discrete method to address the concentrated spin structures around the core of merons. We reveal a logarithmic-scale interaction between merons when their distance is larger than twice their core size and obtain subsequent statistics of meron gas. The model also predicts how these properties of single and paired merons evolve with magnetic exchange interactions, and the results are in excellent agreement with the Monte Carlo simulations using the parameters of real 2D van der Waals magnetic materials. This discrete approach not only shows equilibrium static statistics of meron systems but also is useful to further explore the dynamic properties of merons through the quantified pairing interactions.
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Affiliation(s)
- Xiaobo Lu
- 1Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, United States of America
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States of America
| | - Linghan Zhu
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States of America
| | - Li Yang
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States of America
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15
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Weßels T, Däster S, Murooka Y, Zingsem B, Migunov V, Kruth M, Finizio S, Lu PH, Kovács A, Oelsner A, Müller-Caspary K, Acremann Y, Dunin-Borkowski RE. Continuous illumination picosecond imaging using a delay line detector in a transmission electron microscope. Ultramicroscopy 2022; 233:113392. [PMID: 35016129 DOI: 10.1016/j.ultramic.2021.113392] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/04/2021] [Accepted: 09/09/2021] [Indexed: 11/28/2022]
Abstract
Progress towards analysing transitions between steady states demands improvements in time-resolved imaging, both for fundamental research and for applications in information technology. Transmission electron microscopy is a powerful technique for investigating the atomic structure, chemical composition and electromagnetic properties of materials with high spatial resolution and precision. However, the extraction of information about dynamic processes in the ps time regime is often not possible without extensive modification to the instrument while requiring careful control of the operation conditions to not compromise the beam quality. Here, we avoid these drawbacks by combining a delay line detector with continuous illumination in a transmission electron microscope. We visualize the gyration of a magnetic vortex core in real space and show that magnetization dynamics up to frequencies of 2.3 GHz can be resolved with down to ∼122ps temporal resolution by studying the interaction of an electron beam with a microwave magnetic field. In the future, this approach promises to provide access to resonant dynamics by combining high spatial resolution with sub-ns temporal resolution.
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Affiliation(s)
- Teresa Weßels
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany; Lehrstuhl für Experimentalphysik IV E, RWTH Aachen University, 52056 Aachen, Germany.
| | - Simon Däster
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Yoshie Murooka
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Benjamin Zingsem
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Vadim Migunov
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany; Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52074 Aachen, Germany
| | - Maximilian Kruth
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Peng-Han Lu
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | | | - Knut Müller-Caspary
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany; Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 Munich, Germany
| | - Yves Acremann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
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16
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The Bloch point 3D topological charge induced by the magnetostatic interaction. Sci Rep 2021; 11:21714. [PMID: 34741091 PMCID: PMC8571372 DOI: 10.1038/s41598-021-01175-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 10/13/2021] [Indexed: 12/30/2022] Open
Abstract
A hedgehog or Bloch point is a point-like 3D magnetization configuration in a ferromagnet. Regardless of widely spread treatment of a Bloch point as a topological defect, its 3D topological charge has never been calculated. Here, applying the concepts of the emergent magnetic field and Dirac string, we calculate the 3D topological charge (Hopf index) of a Bloch point and show that due to the magnetostatic energy contribution it has a finite, non-integer value. Thus, Bloch points form a new class of hopfions-3D topological magnetization configurations. The calculated Bloch point non-zero gyrovector leads to important dynamical consequences such as the appearance of topological Hall effect.
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17
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Moon KW, Yang S, Hwang C. Reversible magnetic spiral domain. Sci Rep 2021; 11:20970. [PMID: 34697314 PMCID: PMC8546083 DOI: 10.1038/s41598-021-00016-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/28/2021] [Indexed: 12/01/2022] Open
Abstract
The various spiral structures that exist in nature inspire humanity because of their morphological beauty, and spiral structures are used in various fields, including architecture, engineering, and art. Spiral structures have their own winding directions, and in most spirals, it is difficult to reverse the predetermined winding direction. Here, we show that a rotating spiral exists in magnetic systems for which the winding direction can be easily reversed. A magnetization vector basically has a spiral motion combining a precessional and a damping motion. The application of these basic mechanics to a system composed of magnetic vectors that are affected by a radial current and the Dzyaloshinskii–Moriya interaction forms the rotating magnetic spiral. The winding direction of the magnetic spiral has its own stability, but the direction can be changed using an external magnetic field. This magnetic spiral has a finite size, and the magnetic domain is destroyed at the edge of the spiral, which can create magnetic skyrmions.
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Affiliation(s)
- Kyoung-Woong Moon
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Seungmo Yang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Chanyong Hwang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea.
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18
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Finizio S, Watts B, Raabe J. Why is my image noisy? A look into the terms contributing to a time-resolved X-ray microscopy image. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:1146-1158. [PMID: 34212878 DOI: 10.1107/s1600577521004240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/20/2021] [Indexed: 06/13/2023]
Abstract
Through Monte Carlo simulations, we investigate how various experimental parameters can influence the quality of time-resolved scanning transmission X-ray microscopy images. In particular, the effect of the X-ray photon flux, of the thickness of the investigated samples, and of the frequency of the dynamical process under investigation on the resulting time-resolved image are investigated. The ideal sample and imaging conditions that allow for an optimal image quality are then identifed.
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Affiliation(s)
- Simone Finizio
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Benjamin Watts
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Jörg Raabe
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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19
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Li Z, Dong B, He Y, Chen A, Li X, Tian JH, Yan C. Propagation of Spin Waves in a 2D Vortex Network. NANO LETTERS 2021; 21:4708-4714. [PMID: 34014682 DOI: 10.1021/acs.nanolett.1c00971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Efficient propagation of spin waves in a magnetically coupled vortex is crucial to the development of future magnonic devices. Thus far, only a double vortex can serve as spin-wave emitter or oscillator; the propagation of spin waves in the higher-order vortex is still lacking. Here, we experimentally realize a higher-order vortex (2D vortex network) by a designed nanostructure, containing four cross-type chiral substructures. We employ this vortex network as a waveguide to propagate short-wavelength spin waves (∼100 nm) and demonstrate the possibility of guiding spin waves from one vortex to the network. It is observed that the spin waves can propagate into the network through the nanochannels formed by the Bloch-Néel-type domain walls, with a propagation decay length of several micrometers. This technique paves the way for the development of low-energy, reprogrammable, and miniaturized magnonic devices.
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Affiliation(s)
- Zhenghua Li
- Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, School of Physics and Materials Engineering, Dalian Minzu University, Dalian, 116600, China
| | - Bin Dong
- Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, School of Physics and Materials Engineering, Dalian Minzu University, Dalian, 116600, China
| | - Yangyang He
- Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, School of Physics and Materials Engineering, Dalian Minzu University, Dalian, 116600, China
| | - Aiying Chen
- School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Xiang Li
- School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Jing-Hua Tian
- College of Energy, Soochow Institute for Energy and Materials Innovations & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China
| | - Chenglin Yan
- College of Energy, Soochow Institute for Energy and Materials Innovations & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China
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20
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Teixeira AW, Castillo-Sepúlveda S, Rizzi LG, Nunez AS, Troncoso RE, Altbir D, Fonseca JM, Carvalho-Santos VL. Motion-induced inertial effects and topological phase transitions in skyrmion transport. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:265403. [PMID: 33902016 DOI: 10.1088/1361-648x/abfb8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
When the skyrmion dynamics beyond the particle-like description is considered, this topological structure can deform due to a self-induced field. In this work, we perform Monte Carlo simulations to characterize the skyrmion deformation during its steady movement. In the low-velocity regime, the deformation in the skyrmion shape is quantified by an effective inertial mass, which is related to the dissipative force. When skyrmions move faster, the large self-induced deformation triggers topological transitions. These transitions are characterized by the proliferation of skyrmions and a different total topological charge, which is obtained as a function of the skyrmion velocity. Our findings provide an alternative way to describe the dynamics of a skyrmion that accounts for the deformations of its structure. Furthermore, such motion-induced topological phase transitions make it possible to control the number of ferromagnetic skyrmions through velocity effects.
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Affiliation(s)
- A W Teixeira
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - S Castillo-Sepúlveda
- Facultad de Ingeniería, Universidad Autónoma de Chile, Av. Pedro de Valdivia 425, Providencia, Santiago, Chile
| | - L G Rizzi
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - A S Nunez
- Departamento de Física, FCFM, CEDENNA, Universidad de Chile, Santiago, Chile
| | - R E Troncoso
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - D Altbir
- Departamento de Física, CEDENNA, Universidad de Santiago de Chile, USACH, Santiago, Chile
| | - J M Fonseca
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
| | - V L Carvalho-Santos
- Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil
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21
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Stenning KD, Gartside JC, Dion T, Vanstone A, Arroo DM, Branford WR. Magnonic Bending, Phase Shifting and Interferometry in a 2D Reconfigurable Nanodisk Crystal. ACS NANO 2021; 15:674-685. [PMID: 33320533 DOI: 10.1021/acsnano.0c06894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Strongly interacting nanomagnetic systems are pivotal across next-generation technologies including reconfigurable magnonics and neuromorphic computation. Controlling magnetization states and local coupling between neighboring nanoelements allows vast reconfigurability and a host of associated functionalities. However, existing designs typically suffer from an inability to tailor interelement coupling post-fabrication and nanoelements restricted to a pair of Ising-like magnetization states. Here, we propose a class of reconfigurable magnonic crystals incorporating nanodisks as the functional element. Ferromagnetic nanodisks are crucially bistable in macrospin and vortex states, allowing interelement coupling to be selectively activated (macrospin) or deactivated (vortex). Through microstate engineering, we leverage the distinct coupling behaviors and magnonic band structures of bistable nanodisks to achieve reprogrammable magnonic waveguiding, bending, gating, and phase-shifting across a 2D network. The potential of nanodisk-based magnonics for wave-based computation is demonstrated via an all-magnon interferometer exhibiting XNOR logic functionality. Local microstate control is achieved here via topological magnetic writing using a magnetic force microscope tip.
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Affiliation(s)
- Kilian D Stenning
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jack C Gartside
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Troy Dion
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
| | - Alexander Vanstone
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Daan M Arroo
- London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom
| | - Will R Branford
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
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22
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Tang J, Kong L, Wu Y, Wang W, Chen Y, Wang Y, Li J, Soh Y, Xiong Y, Tian M, Du H. Target Bubbles in Fe 3Sn 2 Nanodisks at Zero Magnetic Field. ACS NANO 2020; 14:10986-10992. [PMID: 32806036 DOI: 10.1021/acsnano.0c04036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report a vortex-like magnetic configuration in uniaxial ferromagnet Fe3Sn2 nanodisks using differential phase contrast scanning transmission electron microscopy. This magnetic configuration is transferred from a conventional magnetic vortex using a zero-magnetic-field warming process and is characterized by a series of concentric cylinder domains. We termed them as "target bubbles" that are identified as three-dimensional depth-modulated magnetic objects in combination with numerical simulations. Target bubbles have room-temperature stability even at zero magnetic field and multiple stable magnetic configurations. These advantages render the target bubble an ideal bit to be an information carrier and can advance magnetic target bubbles toward functionalities in the long term by incorporating emergent degrees of freedom and purely electrically controllable magnetism.
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Affiliation(s)
- Jin Tang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
| | - Lingyao Kong
- School of Physics and Materials Science, Anhui University, Hefei, 230601, China
| | - Yaodong Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
- Universities Joint Key Laboratory of Photoelectric Detection Science and Technology in Anhui Province, Hefei Normal University, Hefei, 230601, China
| | - Weiwei Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Yutao Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
| | - Yihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
| | - Junbo Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
| | - Y Soh
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of Chinese Academy of Sciences, and University of Science and Technology of China, 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 of Chinese Academy of Sciences, and University of Science and Technology of China, Hefei, 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
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23
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Lu X, Fei R, Zhu L, Yang L. Meron-like topological spin defects in monolayer CrCl 3. Nat Commun 2020; 11:4724. [PMID: 32948762 PMCID: PMC7501285 DOI: 10.1038/s41467-020-18573-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 08/26/2020] [Indexed: 11/30/2022] Open
Abstract
Noncollinear spin textures in low-dimensional magnetic systems have been studied for decades because of their extraordinary properties and promising applications derived from the chirality and topological nature. However, material realizations of topological spin states are still limited. Employing first-principles and Monte Carlo simulations, we propose that monolayer chromium trichloride (CrCl3) can be a promising candidate for observing the vortex/antivortex type of topological defects, so-called merons. The numbers of vortices and antivortices are found to be the same, maintaining an overall integer topological unit. By perturbing with external magnetic fields, we show the robustness of these meron pairs and reveal a rich phase space to tune the hybridization between the ferromagnetic order and meron-like defects. The signatures of topological excitations under external magnetic field also provide crucial information for experimental justifications. Our study predicts that two-dimensional magnets with weak spin-orbit coupling can be a promising family for realizing meron-like spin textures.
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Affiliation(s)
- Xiaobo Lu
- Department of Physics, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Ruixiang Fei
- Department of Physics, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Linghan Zhu
- Department of Physics, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Li Yang
- Department of Physics, Washington University in St. Louis, St. Louis, MO, 63130, USA.
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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24
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Reviewing Magnetic Particle Preparation: Exploring the Viability in Biosensing. SENSORS 2020; 20:s20164596. [PMID: 32824330 PMCID: PMC7471997 DOI: 10.3390/s20164596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 12/18/2022]
Abstract
In this review article, we conceptually investigated the requirements of magnetic nanoparticles for their application in biosensing and related them to example systems of our thin-film portfolio. Analyzing intrinsic magnetic properties of different magnetic phases, the size range of the magnetic particles was determined, which is of potential interest for biosensor technology. Different e-beam lithography strategies are utilized to identify possible ways to realize small magnetic particles targeting this size range. Three different particle systems from 500 μm to 50 nm are produced for this purpose, aiming at tunable, vertically magnetized synthetic antiferromagnets, martensitic transformation in a single elliptical, disc-shaped Heusler Ni50Mn32.5Ga17.5 particle and nanocylinders of Co2MnSi-Heusler compound. Perspectively, new applications for these particle systems in combination with microfluidics are addressed. Using the concept of a magnetic on–off ratchet, the most suitable particle system of these three materials is validated with respect to magnetically-driven transport in a microfluidic channel. In addition, options are also discussed for improving the magnetic ratchet for larger particles.
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25
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Deterministic reversal of single magnetic vortex circulation by an electric field. Sci Bull (Beijing) 2020; 65:1260-1267. [PMID: 36747413 DOI: 10.1016/j.scib.2020.04.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/23/2020] [Accepted: 03/27/2020] [Indexed: 02/08/2023]
Abstract
The ability to control magnetic vortex is critical for their potential applications in spintronic devices. Traditional methods including magnetic field, spin-polarized current etc. have been used to flip the core and/or reverse circulation of vortex. However, it is challenging for deterministic electric-field control of the single magnetic vortex textures with time-reversal broken symmetry and no planar magnetic anisotropy. Here it is reported that a deterministic reversal of single magnetic vortex circulation can be driven back and forth by a space-varying strain in multiferroic heterostructures, which is controlled by using a bi-axial pulsed electric field. Phase-field simulation reveals the mechanism of the emerging magnetoelastic energy with the space variation and visualizes the reversal pathway of the vortex. This deterministic electric-field control of the single magnetic vortex textures demonstrates a new approach to integrate the low-dimensional spin texture into the magnetoelectric thin film devices with low energy consumption.
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26
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Rendell-Bhatti F, Lamb RJ, van der Jagt JW, Paterson GW, Swagten HJM, McGrouther D. Spontaneous creation and annihilation dynamics and strain-limited stability of magnetic skyrmions. Nat Commun 2020; 11:3536. [PMID: 32669654 PMCID: PMC7363836 DOI: 10.1038/s41467-020-17338-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/24/2020] [Indexed: 11/08/2022] Open
Abstract
Magnetic skyrmions are topological magnetic spin structures exhibiting particle-like behaviour. They are of strong interest from a fundamental viewpoint and for application, where they have potential to act as information carriers in future low-power computing technologies. Importantly, skyrmions have high physical stability because of topological protection. However, they have potential to deform according to their local energy environment. Here we demonstrate that, in regions of high exchange energy density, skyrmions may exhibit such extreme deformation that spontaneous merging with nearest neighbours or spawning new skyrmions is favoured to attain a lower energy state. Using transmission electron microscopy and a high-speed imaging detector, we observe dynamics involving distinct configurational states, in which transitions are accompanied by spontaneous creation or annihilation of skyrmions. These observations raise important questions regarding the limits of skyrmion stability and topological charge conservation, while also suggesting a means of control of skyrmion creation and annihilation.
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Affiliation(s)
| | - Raymond J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Johannes W van der Jagt
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ, Eindhoven, The Netherlands
| | - Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Henk J M Swagten
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ, Eindhoven, The Netherlands
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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27
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Ramasubramanian L, Kákay A, Fowley C, Yildirim O, Matthes P, Sorokin S, Titova A, Hilliard D, Böttger R, Hübner R, Gemming S, Schulz SE, Kronast F, Makarov D, Fassbender J, Deac A. Tunable Magnetic Vortex Dynamics in Ion-Implanted Permalloy Disks. ACS APPLIED MATERIALS & INTERFACES 2020; 12:27812-27818. [PMID: 32442364 DOI: 10.1021/acsami.0c08024] [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
Nanoscale, low-phase-noise, tunable transmitter-receiver links are key for enabling the progress of wireless communication. We demonstrate that vortex-based spin-torque nano-oscillators, which are intrinsically low-noise devices because of their topologically protected magnetic structure, can achieve frequency tunability when submitted to local ion implantation. In the experiments presented here, the gyrotropic mode is excited with spin-polarized alternating currents and anisotropic magnetoresistance measurements yield discrete frequencies from a single device. Indeed, chromium-implanted regions of permalloy disks exhibit different saturation magnetization than neighboring, non-irradiated areas, and thus different resonance frequency, corresponding to the specific area where the core is gyrating. Our study proves that such devices can be fabricated without the need for further lithographical steps, suggesting ion irradiation can be a viable and cost-effective fabrication method for densely packed networks of oscillators.
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Affiliation(s)
- Lakshmi Ramasubramanian
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - Attila Kákay
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Ciarán Fowley
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Oguz Yildirim
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- EMPA-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Patrick Matthes
- Fraunhofer Institute for Electronic Nano Systems, Chemnitz 09126, Germany
| | - Serhii Sorokin
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Institute of Solid State Physics, TU Dresden, Dresden 01069, Germany
| | - Aleksandra Titova
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Institute of Solid State Physics, TU Dresden, Dresden 01069, Germany
| | - Donovan Hilliard
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - Roman Böttger
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - René Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Sibylle Gemming
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - Stefan E Schulz
- Technische Universität Chemnitz, Chemnitz 09126, Germany
- Fraunhofer Institute for Electronic Nano Systems, Chemnitz 09126, Germany
| | - Florian Kronast
- Helmholtz-Zentrum Berlin für Materialen und Energie, Berlin 12489, Germany
| | - Denys Makarov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Jürgen Fassbender
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- Institute of Solid State Physics, TU Dresden, Dresden 01069, Germany
| | - Alina Deac
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
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28
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Luo YM, Wu YZ, Qian ZH, Wen JH, Li H, Yu CQ, Zhu LY, Wang L, Xu L, Bai R, Zhou TJ. Fast and deterministic switching of a vortex core induced by an out-of-plane current in notch disks. NANOTECHNOLOGY 2020; 31:205302. [PMID: 31995533 DOI: 10.1088/1361-6528/ab70f9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The magnetic vortex, as one of the most interesting magnetic solitons, has attracted great interest over the past two decades. A fast and reliable method to switch vortex polarity and chirality is one of the key issues for various applications. Based on micromagnetic simulation, here we report a fast, low energy cost and deterministic switching of a vortex core, by the designing of a notch structure in disks and the use of out-of-plane current geometry. We demonstrate that with such a design, the multiple switching problems found in notch disk systems can be avoided. Furthermore, the switching time can be reduced by more than 50% compared with disks without notches.
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Affiliation(s)
- Y M Luo
- Center for Integrated Spintronic Devices, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, People's Republic of China
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29
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Donnelly C, Finizio S, Gliga S, Holler M, Hrabec A, Odstrčil M, Mayr S, Scagnoli V, Heyderman LJ, Guizar-Sicairos M, Raabe J. Time-resolved imaging of three-dimensional nanoscale magnetization dynamics. NATURE NANOTECHNOLOGY 2020; 15:356-360. [PMID: 32094498 DOI: 10.1038/s41565-020-0649-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/27/2020] [Indexed: 05/25/2023]
Abstract
Understanding and control of the dynamic response of magnetic materials with a three-dimensional magnetization distribution is important both fundamentally and for technological applications. From a fundamental point of view, the internal magnetic structure and dynamics in bulk materials still need to be mapped1, including the dynamic properties of topological structures such as vortices2, magnetic singularities3 or skyrmion lattices4. From a technological point of view, the response of inductive materials to magnetic fields and spin-polarized currents is essential for magnetic sensors and data storage devices5. Here, we demonstrate time-resolved magnetic laminography, a pump-probe technique, which offers access to the temporal evolution of a three-dimensional magnetic microdisc with nanoscale resolution, and with a synchrotron-limited temporal resolution of 70 ps. We image the dynamic response to a 500 MHz magnetic field of the complex three-dimensional magnetization in a two-phase bulk magnet with a lateral spatial resolution of 50 nm. This is achieved with a stroboscopic measurement consisting of eight time steps evenly spaced over 2 ns. These measurements map the spatial transition between domain wall motion and the dynamics of a uniform magnetic domain that is attributed to variations in the magnetization state across the phase boundary. Our technique, which probes three-dimensional magnetic structures with temporal resolution, enables the experimental investigation of functionalities arising from dynamic phenomena in bulk and three-dimensional patterned nanomagnets6.
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Affiliation(s)
- Claire Donnelly
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
- Paul Scherrer Institute, Villigen, Switzerland.
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland.
| | | | - Sebastian Gliga
- Paul Scherrer Institute, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, UK
| | | | - Aleš Hrabec
- Paul Scherrer Institute, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland
- Laboratory for Magnetism and Interface Physics, Department of Materials, ETH Zurich, Zurich, Switzerland
| | | | - Sina Mayr
- Paul Scherrer Institute, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Valerio Scagnoli
- Paul Scherrer Institute, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Laura J Heyderman
- Paul Scherrer Institute, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, Zurich, Switzerland
| | | | - Jörg Raabe
- Paul Scherrer Institute, Villigen, Switzerland.
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30
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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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31
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Fokin N, Grothe T, Mamun A, Trabelsi M, Klöcker M, Sabantina L, Döpke C, Blachowicz T, Hütten A, Ehrmann A. Magnetic Properties of Electrospun Magnetic Nanofiber Mats after Stabilization and Carbonization. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E1552. [PMID: 32230911 PMCID: PMC7177732 DOI: 10.3390/ma13071552] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 11/30/2022]
Abstract
Magnetic nanofibers are of great interest in basic research, as well as for possible applications in spintronics and neuromorphic computing. Here we report on the preparation of magnetic nanofiber mats by electrospinning polyacrylonitrile (PAN)/nanoparticle solutions, creating a network of arbitrarily oriented nanofibers with a high aspect ratio. Since PAN is a typical precursor for carbon, the magnetic nanofiber mats were stabilized and carbonized after electrospinning. The magnetic properties of nanofiber mats containing magnetite or nickel ferrite nanoparticles were found to depend on the nanoparticle diameters and the potential after-treatment, as compared with raw nanofiber mats. Micromagnetic simulations underlined the different properties of both magnetic materials. Atomic force microscopy and scanning electron microscopy images revealed nearly unchanged morphologies after stabilization without mechanical fixation, which is in strong contrast to pure PAN nanofiber mats. While carbonization at 500 °C left the morphology unaltered, as compared with the stabilized samples, stronger connections between adjacent fibers were formed during carbonization at 800 °C, which may be supportive of magnetic data transmission.
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Affiliation(s)
- Nadine Fokin
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, 33615 Bielefeld, Germany; (N.F.); (A.H.)
| | - Timo Grothe
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
| | - Al Mamun
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
| | - Marah Trabelsi
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
- Ecole Nationale d’Ingénieurs de Sfax (ENIS), Sfax 3038, Tunisia
| | - Michaela Klöcker
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
| | - Lilia Sabantina
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
| | - Christoph Döpke
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
| | - Tomasz Blachowicz
- Institute of Physics–CSE, Silesian University of Technology, 44-100 Gliwice, Poland;
| | - Andreas Hütten
- Department of Physics, Center for Spinelectronic Materials and Devices, Bielefeld University, 33615 Bielefeld, Germany; (N.F.); (A.H.)
| | - Andrea Ehrmann
- Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany; (T.G.); (A.M.); (M.T.); (M.K.); (L.S.); (C.D.)
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32
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Ju WM, Bickel JE, Pradhan N, Aidala KE, Tuominen M. Reversing the circulation of ferromagnetic nanodisks with a local circular magnetic field. NANOTECHNOLOGY 2020; 31:115205. [PMID: 31775135 DOI: 10.1088/1361-6528/ab5c3c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ferromagnetic nanodisks have a unique closed-flux vortex state with two degrees of freedom that results in four different magnetization states that are degenerate in energy and stable against thermal fluctuations. Such disks could be interesting for magnetic memory devices if the independent switching of each degree of freedom can be realized. Polarity switching of the vortex core has been demonstrated, but it is difficult to manipulate switching of the vortex due to the high symmetry of the structure. In this work, we reverse the circulation direction of a circular ferromagnetic nanodisk by applying a local circular Oersted field via a metallic atomic force microscope tip placed at the center of the disk. The resulting field reverses the circulation of the vortex without switching the orientation of the core. Switching of the vortex is accomplished by the sudden increase in the current that occurs when there is dielectric breakdown of a thin insulating layer on top of the disk. Micromagnetic simulations indicate that a line current concentrated in the center of a nanodisk can reverse the magnetization of the disk at a value over one order of magnitude smaller than the current required if the current is instead uniformly distributed across the cross section of disk. These results can be applied to reducing the switching current in circularly symmetric device structures.
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Affiliation(s)
- Wen-Ming Ju
- Physics Department, University of Massachusetts at Amherst, MA 01003, United States of America
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33
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Ghidini M, Mansell R, Pellicelli R, Pesquera D, Nair B, Moya X, Farokhipoor S, Maccherozzi F, Barnes CHW, Cowburn RP, Dhesi SS, Mathur ND. Voltage-driven annihilation and creation of magnetic vortices in Ni discs. NANOSCALE 2020; 12:5652-5657. [PMID: 32101212 DOI: 10.1039/c9nr08672b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using photoemission electron microscopy (PEEM) to image ferromagnetism in polycrystalline Ni disks, and ferroelectricity in their single-crystal BaTiO3 substrates, we find that voltage-driven 90° ferroelectric domain switching serves to reversibly annihilate each magnetic vortex via uniaxial compressive strain, and that the orientation of the resulting bi-domain reveals the chirality of the annihilated vortex. Micromagnetic simulations reveal that only 60% of this strain is required for annihilation. Voltage control of magnetic vortices is novel, and should be energetically favourable with respect to the use of a magnetic field or an electrical current. In future, stray field from bi-domains could be exploited to read vortex chirality. Given that core polarity can already be read via stray field, our work represents a step towards four-state low-power memory applications.
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Affiliation(s)
- M Ghidini
- Department of Mathematics, Physics and Computer Science, University of Parma, 43124 Parma, Italy.
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34
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Díaz J, Gargiani P, Quirós C, Redondo C, Morales R, Álvarez-Prado LM, Martín JI, Scholl A, Ferrer S, Vélez M, Valvidares SM. Chiral asymmetry detected in a 2D array of permalloy square nanomagnets using circularly polarized x-ray resonant magnetic scattering. NANOTECHNOLOGY 2020; 31:025702. [PMID: 31546237 DOI: 10.1088/1361-6528/ab46d7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The sensitivity of circularly polarized x-ray resonant magnetic scattering (CXRMS) to chiral asymmetry has been demonstrated. The study was performed on a 2D array of Permalloy (Py) square nanomagnets of 700 nm lateral size arranged in a chess pattern, in a square lattice of 1000 nm lattice parameter. Previous x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) images on this sample showed the formation of vortices at remanence and a preference in their chiral state. The magnetic hysteresis loops of the array along the diagonal axis of the squares indicate a non-negligible and anisotropic interaction between vortices. The intensity of the magnetic scattering using circularly polarized light along one of the diagonal axes of the square magnets becomes asymmetric in intensity in the direction transversal to the incident plane at fields where the vortex states are formed. The asymmetry sign is inverted when the direction of the applied magnetic field is inverted. The result is the expected in the presence of an unbalanced chiral distribution. The effect is observed by CXRMS due to the interference between the charge scattering and the magnetic scattering.
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Affiliation(s)
- J Díaz
- Depto. Física, Universidad de Oviedo, E-33007 Oviedo, Spain. CINN (CSIC-Univ. de Oviedo), E-33940 El Entrego, Spain
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35
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Lendinez S, Jungfleisch MB. Magnetization dynamics in artificial spin ice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:013001. [PMID: 31600143 DOI: 10.1088/1361-648x/ab3e78] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this topical review, we present key results of studies on magnetization dynamics in artificial spin ice (ASI), which are arrays of magnetically interacting nanostructures. Recent experimental and theoretical progress in this emerging area, which is at the boundary between research on frustrated magnetism and high-frequency studies of artificially created nanomagnets, is reviewed. The exploration of ASI structures has revealed fascinating discoveries in correlated spin systems. Artificially created spin ice lattices offer unique advantages as they allow for a control of the interactions between the elements by their geometric properties and arrangement. Magnonics, on the other hand, is a field that explores spin dynamics in the gigahertz frequency range in magnetic micro- and nanostructures. In this context, magnonic crystals are particularly important as they allow the modification of spin-wave properties and the observation of band gaps in the resonance spectra. Very recently, there has been considerable progress, experimentally and theoretically, in combining aspects of both fields-artificial spin ice and magnonics-enabling new functionalities in magnonic and spintronic applications using ASI, as well as providing a deeper understanding of geometrical frustration in the gigahertz range. Different approaches for the realization of ASI structures and their experimental characterization in the high-frequency range are described and the appropriate theoretical models and simulations are reviewed. Special attention is devoted to linking these findings to the quasi-static behavior of ASI and dynamic investigations in magnonics in an effort to bridge the gap between both areas further and to stimulate new research endeavors.
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Affiliation(s)
- S Lendinez
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, United States of America
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36
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Gao N, Je SG, Im MY, Choi JW, Yang M, Li Q, Wang TY, Lee S, Han HS, Lee KS, Chao W, Hwang C, Li J, Qiu ZQ. Creation and annihilation of topological meron pairs in in-plane magnetized films. Nat Commun 2019; 10:5603. [PMID: 31811144 PMCID: PMC6898613 DOI: 10.1038/s41467-019-13642-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 11/18/2019] [Indexed: 11/10/2022] Open
Abstract
Merons which are topologically equivalent to one-half of skyrmions can exist only in pairs or groups in two-dimensional (2D) ferromagnetic (FM) systems. The recent discovery of meron lattice in chiral magnet Co8Zn9Mn3 raises the immediate challenging question that whether a single meron pair, which is the most fundamental topological structure in any 2D meron systems, can be created and stabilized in a continuous FM film? Utilizing winding number conservation, we develop a new method to create and stabilize a single pair of merons in a continuous Py film by local vortex imprinting from a Co disk. By observing the created meron pair directly within a magnetic field, we determine its topological structure unambiguously and explore the topological effect in its creation and annihilation processes. Our work opens a pathway towards developing and controlling topological structures in general magnetic systems without the restriction of perpendicular anisotropy and Dzyaloshinskii–Moriya interaction. A meron is one half of a skyrmion but whether a single meron pair can be created and stabilized remains a challenging question. Here, Gao et al. develop a method to create and stabilize individual pairs of merons in a continuous Py film by local vortex imprinting from Co disks.
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Affiliation(s)
- N Gao
- Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing, 100029, China.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - S -G Je
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - M -Y Im
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Emerging Materials Science, DGIST, Daegu, Korea
| | - J W Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - M Yang
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Q Li
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - T Y Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - S Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - H -S Han
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - K -S Lee
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - W Chao
- Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - C Hwang
- Korea Research Institute of Standards and Science, Yuseong, Daejeon, 305-340, Korea
| | - J Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
| | - Z Q Qiu
- Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.
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Wang XS, Qaiumzadeh A, Brataas A. Current-Driven Dynamics of Magnetic Hopfions. PHYSICAL REVIEW LETTERS 2019; 123:147203. [PMID: 31702184 DOI: 10.1103/physrevlett.123.147203] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Indexed: 06/10/2023]
Abstract
Topological magnetic textures have attracted considerable interest since they exhibit new properties and might be useful in information technology. Magnetic hopfions are three-dimensional (3D) spatial variations in the magnetization with a nontrivial Hopf index. We find that, in ferromagnetic materials, two types of hopfions, Bloch-type and Néel-type hopfions, can be excited as metastable states in the presence of bulk and interfacial Dzyaloshinskii-Moriya interactions, respectively. We further investigate how hopfions can be driven by currents via spin-transfer torques (STTs) and spin-Hall torques (SHTs). Distinct from 2D ferromagnetic skyrmions, hopfions have a vanishing gyrovector. Consequently, there are no undesirable Hall effects. Néel-type hopfions move along the current direction via both STT and SHT, while Bloch-type hopfions move either transverse to the current direction via SHT or parallel to the current direction via STT. Our findings open the door to utilizing hopfions as information carriers.
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Affiliation(s)
- X S Wang
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - A Qaiumzadeh
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - A Brataas
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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38
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Di Giorgio C, Scarfato A, Longobardi M, Bobba F, Iavarone M, Novosad V, Karapetrov G, Cucolo AM. Quantitative magnetic force microscopy using calibration on superconducting flux quanta. NANOTECHNOLOGY 2019; 30:314004. [PMID: 30995619 DOI: 10.1088/1361-6528/ab1a4d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present a new procedure that takes advantage of the magnetic flux quantization of superconducting vortices to calibrate the magnetic properties of tips for magnetic force microscopy (MFM). Indeed, a superconducting vortex, whose quantized flux is dependent upon Plank constant, speed of light and electron charge, behaves as a very well defined magnetic reference object. The proposed calibration procedure has been tested on new and worn tips and shows that the monopole point-like approximation of the probe is a reliable model. This procedure has been then applied to perform quantitative MFM experiments on a soft ferromagnetic thin film of permalloy, leading to the determination of the local out-of-plane component of the canted magnetization, together with its spatial variations across a few μm2 scan area.
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Affiliation(s)
- Cinzia Di Giorgio
- Physics Department 'E.R. Caianiello', University of Salerno, Fisciano, Italy. CNR-SPIN, Fisciano, Italy
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39
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Temporal and spectral fingerprints of ultrafast all-coherent spin switching. Nature 2019; 569:383-387. [PMID: 31092937 DOI: 10.1038/s41586-019-1174-7] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 03/04/2019] [Indexed: 11/08/2022]
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40
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Jia C, Ma D, Schäffer AF, Berakdar J. Twisted magnon beams carrying orbital angular momentum. Nat Commun 2019; 10:2077. [PMID: 31064991 PMCID: PMC6504950 DOI: 10.1038/s41467-019-10008-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 04/12/2019] [Indexed: 11/09/2022] Open
Abstract
Low-energy eigenmode excitations of ferromagnets are spin waves or magnons that can be triggered and guided in magnonic circuits without Ohmic losses and hence are attractive for communicating and processing information. Here we present new types of spin waves that carry a definite and electrically controllable orbital angular momentum (OAM) constituting twisted magnon beams. We show how twisted beams emerge in magnonic waveguides and how to topologically quantify and steer them. A key finding is that the topological charge associated with OAM of a particular beam is tunable externally and protected against magnetic damping. Coupling to an applied electric field via the Aharanov-Casher effect allows for varying the topological charge. This renders possible OAM-based robust, low-energy consuming multiplex magnonic computing, analogously to using photonic OAM in optical communications, and high OAM-based entanglement studies, but here at shorter wavelengths, lower energy consumption, and ready integration in magnonic circuits.
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Affiliation(s)
- Chenglong Jia
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education and Institute of Theoretical Physics, Lanzhou University, 73000, Lanzhou, China.
| | - Decheng Ma
- Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education and Institute of Theoretical Physics, Lanzhou University, 73000, Lanzhou, China
| | - Alexander F Schäffer
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany
| | - Jamal Berakdar
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.
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41
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Döpke C, Grothe T, Steblinski P, Klöcker M, Sabantina L, Kosmalska D, Blachowicz T, Ehrmann A. Magnetic Nanofiber Mats for Data Storage and Transfer. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E92. [PMID: 30642028 PMCID: PMC6359166 DOI: 10.3390/nano9010092] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/04/2019] [Accepted: 01/08/2019] [Indexed: 11/16/2022]
Abstract
Electrospun nanofiber mats may serve as new hardware for neuromorphic computing. To enable data storage and transfer in them, they should be magnetic, possibly electrically conductive and able to respond to further external impulses. Here we report on creating magnetic nanofiber mats, consisting of magnetically doped polymer nanofibers for data transfer and polymer beads containing larger amounts of magnetic nanoparticles for storage purposes. Using magnetite and iron nickel oxide nanoparticles, a broad range of doping ratios could be electrospun with a needleless technique, resulting in magnetic nanofiber mats with varying morphologies and different amounts of magnetically doped beads.
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Affiliation(s)
- Christoph Döpke
- Faculty of Engineering and Mathematics, ITES, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany.
| | - Timo Grothe
- Faculty of Engineering and Mathematics, ITES, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany.
| | - Pawel Steblinski
- Institute of Physics-Center for Science and Education, Silesian University of Technology, 44-100 Gliwice, Poland.
- Faculty of Electronics and Informatics, Koszalin University of Technology, 75-453 Koszalin, Poland.
| | - Michaela Klöcker
- Faculty of Engineering and Mathematics, ITES, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany.
| | - Lilia Sabantina
- Faculty of Engineering and Mathematics, ITES, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany.
| | - Dorota Kosmalska
- Institute of Physics-Center for Science and Education, Silesian University of Technology, 44-100 Gliwice, Poland.
| | - Tomasz Blachowicz
- Institute of Physics-Center for Science and Education, Silesian University of Technology, 44-100 Gliwice, Poland.
| | - Andrea Ehrmann
- Faculty of Engineering and Mathematics, ITES, Bielefeld University of Applied Sciences, 33619 Bielefeld, Germany.
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42
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Dhankhar M, Vaňatka M, Urbanek M. Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques. J Vis Exp 2018. [PMID: 30010671 PMCID: PMC6102033 DOI: 10.3791/57817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.
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43
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Fu X, Pollard SD, Chen B, Yoo BK, Yang H, Zhu Y. Optical manipulation of magnetic vortices visualized in situ by Lorentz electron microscopy. SCIENCE ADVANCES 2018; 4:eaat3077. [PMID: 30035226 PMCID: PMC6054509 DOI: 10.1126/sciadv.aat3077] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/04/2018] [Indexed: 05/03/2023]
Abstract
Understanding the fundamental dynamics of topological vortex and antivortex naturally formed in microscale/nanoscale ferromagnetic building blocks under external perturbations is crucial to magnetic vortex-based information processing and spintronic devices. All previous studies have focused on magnetic vortex-core switching via external magnetic fields, spin-polarized currents, or spin waves, which have largely prohibited the investigation of novel spin configurations that could emerge from the ground states in ferromagnetic disks and their underlying dynamics. We report in situ visualization of femtosecond laser quenching-induced magnetic vortex changes in various symmetric ferromagnetic Permalloy disks by using Lorentz phase imaging of four-dimensional electron microscopy that enables in situ laser excitation. Besides the switching of magnetic vortex chirality and polarity, we observed with distinct occurrence frequencies a plenitude of complex magnetic structures that have never been observed by magnetic field- or current-assisted switching. These complex magnetic structures consist of a number of newly created topological magnetic defects (vortex and antivortex) strictly conserving the topological winding number, demonstrating the direct impact of topological invariants on magnetization dynamics in ferromagnetic disks. Their spin configurations show mirror or rotation symmetry due to the geometrical confinement of the disks. Combined micromagnetic simulations with the experimental observations reveal the underlying magnetization dynamics and formation mechanism of the optical quenching-induced complex magnetic structures. Their distinct occurrence rates are pertinent to their formation-growth energetics and pinning effects at the disk edge. On the basis of these findings, we propose a paradigm of optical quenching-assisted fast switching of vortex cores for the control of magnetic vortex-based information recording and spintronic devices.
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Affiliation(s)
- Xuewen Fu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Shawn D. Pollard
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Bin Chen
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Byung-Kuk Yoo
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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44
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Zhu S, Fu J, Li H, Zhu L, Hu Y, Xia W, Zhang X, Peng Y, Zhang J. Direct Observation of Magnetocrystalline Anisotropy Tuning Magnetization Configurations in Uniaxial Magnetic Nanomaterials. ACS NANO 2018; 12:3442-3448. [PMID: 29558619 DOI: 10.1021/acsnano.8b00058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Discovering the effect of magnetic anisotropy on the magnetization configurations of magnetic nanomaterials is essential and significant for not only enriching the fundamental knowledge of magnetics but also facilitating the designs of desired magnetic nanostructures for diverse technological applications, such as data storage devices, spintronic devices, and magnetic nanosensors. Herein, we present a direct observation of magnetocrystalline anisotropy tuning magnetization configurations in uniaxial magnetic nanomaterials with hexagonal structure by means of three modeled samples. The magnetic configuration in polycrystalline BaFe12O19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. Both single crystalline BaFe12O19 nanoslice and individual particles of single-particle-chain BaFe12O19 nanowire appear in a single domain state, revealing a dominant role of magnetocrystalline anisotropy in the magnetization configuration of uniaxial magnetic nanomaterials. These observations are further verified by micromagnetic computational simulations.
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Affiliation(s)
- Shimeng Zhu
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Jiecai Fu
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Hongli Li
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Liu Zhu
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Yang Hu
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Weixing Xia
- Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering , Chinese Academy of Sciences , Ningbo 315201 , P. R. China
| | - Xixiang Zhang
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 239955 , Kingdom of Saudi Arabia
| | - Yong Peng
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
| | - Junli Zhang
- Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , P. R. China
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology (KAUST) , Thuwal 239955 , Kingdom of Saudi Arabia
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45
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Salem MS, Tejo F, Zierold R, Sergelius P, Moreno JMM, Goerlitz D, Nielsch K, Escrig J. Composition and diameter modulation of magnetic nanowire arrays fabricated by a novel approach. NANOTECHNOLOGY 2018; 29:065602. [PMID: 29226847 DOI: 10.1088/1361-6528/aaa095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Straight magnetic nanowires composed of nickel and permalloy segments having different diameters are synthesized using a promising approach. This approach involves the controlled electrodeposition of each magnetic material into specially designed diameter-modulated porous alumina templates. Standard alumina templates are exposed to pore widening followed by a protective coating of the pore wall with ultrathin silica and further anodization. Micromagnetic simulations are employed to investigate the process of magnetization reversal in the fabricated nanowires when the magnetic materials exchange their places in the thick and thin segments. It is found that the magnetization reversal occurs by the propagation of transverse domain wall (DW) when the thick segment is composed of permalloy. However, the reversal process proceeds by the propagation of vortex DW when permalloy is located at the thin segment.
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Abstract
A novel approach to investigate geometrical frustration is introduced using two-dimensional magnonic vortex crystals. The frustration of the crystal can be manipulated and turned on and off dynamically on the timescale of milliseconds. The vortices are studied using scanning transmission x-ray microscopy and ferromagnetic resonance spectroscopy. They are arranged analogous to the nanomagnets in artificial spin-ice systems. The polarization state of the vortices is tuned in a way that geometrical frustration arises. We demonstrate that frustrated polarization states and non-frustrated states can be tuned to the crystal by changing the frequency of the state formation process.
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47
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Kfir O, Zayko S, Nolte C, Sivis M, Möller M, Hebler B, Arekapudi SSPK, Steil D, Schäfer S, Albrecht M, Cohen O, Mathias S, Ropers C. Nanoscale magnetic imaging using circularly polarized high-harmonic radiation. SCIENCE ADVANCES 2017; 3:eaao4641. [PMID: 29250601 PMCID: PMC5732000 DOI: 10.1126/sciadv.aao4641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/15/2017] [Indexed: 05/05/2023]
Abstract
This work demonstrates nanoscale magnetic imaging using bright circularly polarized high-harmonic radiation. We utilize the magneto-optical contrast of worm-like magnetic domains in a Co/Pd multilayer structure, obtaining quantitative amplitude and phase maps by lensless imaging. A diffraction-limited spatial resolution of 49 nm is achieved with iterative phase reconstruction enhanced by a holographic mask. Harnessing the exceptional coherence of high harmonics, this approach will facilitate quantitative, element-specific, and spatially resolved studies of ultrafast magnetization dynamics, advancing both fundamental and applied aspects of nanoscale magnetism.
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Affiliation(s)
- Ofer Kfir
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
- Solid State Institute and Physics Department, Technion–Israel Institute of Technology, Haifa 32000, Israel
- Corresponding author. (O.K.); (C.R.)
| | - Sergey Zayko
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Christina Nolte
- 1st Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Murat Sivis
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Marcel Möller
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Birgit Hebler
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
| | | | - Daniel Steil
- 1st Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Sascha Schäfer
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
| | - Manfred Albrecht
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
| | - Oren Cohen
- Solid State Institute and Physics Department, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - Stefan Mathias
- 1st Physical Institute, University of Göttingen, Göttingen 37077, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
| | - Claus Ropers
- 4th Physical Institute, University of Göttingen, Göttingen 37077, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
- Corresponding author. (O.K.); (C.R.)
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49
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Wong DW, Gan WL, Liu N, Lew WS. Magneto-actuated cell apoptosis by biaxial pulsed magnetic field. Sci Rep 2017; 7:10919. [PMID: 28883430 PMCID: PMC5589943 DOI: 10.1038/s41598-017-11279-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/22/2017] [Indexed: 12/04/2022] Open
Abstract
We report on a highly efficient magneto-actuated cancer cell apoptosis method using a biaxial pulsed magnetic field configuration, which maximizes the induced magnetic torque. The light transmissivity dynamics show that the biaxial magnetic field configuration can actuate the magnetic nanoparticles with higher responsiveness over a wide range of frequencies as compared to uniaxial field configurations. Its efficacy was demonstrated in in vitro cell destruction experiments with a greater reduction in cell viability. Magnetic nanoparticles with high aspect ratios were also found to form a triple vortex magnetization at remanence which increases its low field susceptibility. This translates to a larger magneto-mechanical actuated force at low fields and 12% higher efficacy in cell death as compared to low aspect ratio nanoparticles.
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Affiliation(s)
- De Wei Wong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Wei Liang Gan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Ning Liu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore.
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50
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Zheng Y, Chen WJ. Characteristics and controllability of vortices in ferromagnetics, ferroelectrics, and multiferroics. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:086501. [PMID: 28155849 DOI: 10.1088/1361-6633/aa5e03] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Topological defects in condensed matter are attracting e significant attention due to their important role in phase transition and their fascinating characteristics. Among the various types of matter, ferroics which possess a switchable physical characteristic and form domain structure are ideal systems to form topological defects. In particular, a special class of topological defects-vortices-have been found to commonly exist in ferroics. They often manifest themselves as singular regions where domains merge in large systems, or stabilize as novel order states instead of forming domain structures in small enough systems. Understanding the characteristics and controllability of vortices in ferroics can provide us with deeper insight into the phase transition of condensed matter and also exciting opportunities in designing novel functional devices such as nano-memories, sensors, and transducers based on topological defects. In this review, we summarize the recent experimental and theoretical progress in ferroic vortices, with emphasis on those spin/dipole vortices formed in nanoscale ferromagnetics and ferroelectrics, and those structural domain vortices formed in multiferroic hexagonal manganites. We begin with an overview of this field. The fundamental concepts of ferroic vortices, followed by the theoretical simulation and experimental methods to explore ferroic vortices, are then introduced. The various characteristics of vortices (e.g. formation mechanisms, static/dynamic features, and electronic properties) and their controllability (e.g. by size, geometry, external thermal, electrical, magnetic, or mechanical fields) in ferromagnetics, ferroelectrics, and multiferroics are discussed in detail in individual sections. Finally, we conclude this review with an outlook on this rapidly developing field.
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Affiliation(s)
- Yue Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, People's Republic of China. Micro&Nano Physics and Mechanics Research Laboratory, School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, People's Republic of China
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