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Nomura T, Zhang XX, Takagi R, Karube K, Kikkawa A, Taguchi Y, Tokura Y, Zherlitsyn S, Kohama Y, Seki S. Nonreciprocal Phonon Propagation in a Metallic Chiral Magnet. PHYSICAL REVIEW LETTERS 2023; 130:176301. [PMID: 37172228 DOI: 10.1103/physrevlett.130.176301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/06/2023] [Indexed: 05/14/2023]
Abstract
The phonon magnetochiral effect (MChE) is the nonreciprocal acoustic and thermal transports of phonons caused by the simultaneous breaking of the mirror and time-reversal symmetries. So far, the phonon MChE has been observed only in a ferrimagnetic insulator Cu_{2}OSeO_{3}, where the nonreciprocal response disappears above the Curie temperature of 58 K. Here, we study the nonreciprocal acoustic properties of a room-temperature ferromagnet Co_{9}Zn_{9}Mn_{2} for unveiling the phonon MChE close to room temperature. Surprisingly, the nonreciprocity in this metallic compound is enhanced at higher temperatures and observed up to 250 K. This clear contrast between insulating Cu_{2}OSeO_{3} and metallic Co_{9}Zn_{9}Mn_{2} suggests that metallic magnets have a mechanism to enhance the nonreciprocity at higher temperatures. From the ultrasound and microwave-spectroscopy experiments, we conclude that the magnitude of the phonon MChE of Co_{9}Zn_{9}Mn_{2} mostly depends on the Gilbert damping, which increases at low temperatures and hinders the magnon-phonon hybridization. Our results suggest that the phonon nonreciprocity could be further enhanced by engineering the magnon band of materials.
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Affiliation(s)
- T Nomura
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Tokyo Denki University, Adachi, Tokyo 120-8551, Japan
| | - X-X Zhang
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - R Takagi
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - K Karube
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - A Kikkawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Y Taguchi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Y Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
| | - S Zherlitsyn
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Y Kohama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - S Seki
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
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2
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Aqeel A, Sahliger J, Taniguchi T, Mändl S, Mettus D, Berger H, Bauer A, Garst M, Pfleiderer C, Back CH. Microwave Spectroscopy of the Low-Temperature Skyrmion State in Cu_{2}OSeO_{3}. PHYSICAL REVIEW LETTERS 2021; 126:017202. [PMID: 33480751 DOI: 10.1103/physrevlett.126.017202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
In the cubic chiral magnet Cu_{2}OSeO_{3} a low-temperature skyrmion state (LTS) and a concomitant tilted conical state are observed for magnetic fields parallel to ⟨100⟩. Here, we report on the dynamic resonances of these novel magnetic states. After promoting the nucleation of the LTS by means of field cycling, we apply broadband microwave spectroscopy in two experimental geometries that provide either predominantly in-plane or out-of-plane excitation. By comparing the results to linear spin-wave theory, we clearly identify resonant modes associated with the tilted conical state, the gyrational and breathing modes associated with the LTS, as well as the hybridization of the breathing mode with a dark octupole gyration mode mediated by the magnetocrystalline anisotropies. Most intriguingly, our findings suggest that under decreasing fields the hexagonal skyrmion lattice becomes unstable with respect to an oblique deformation, reflected in the formation of elongated skyrmions.
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Affiliation(s)
- Aisha Aqeel
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Jan Sahliger
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Takuya Taniguchi
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Stefan Mändl
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Denis Mettus
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Helmuth Berger
- École Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Andreas Bauer
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - Markus Garst
- Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany
- Institute for quantum materials and technology, Karlsruhe Institute of Technology, D-76344 Eggenstein-Leopoldshafen, Germany
| | | | - Christian H Back
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), D-80799 München, Germany
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3
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Jena J, Göbel B, Ma T, Kumar V, Saha R, Mertig I, Felser C, Parkin SSP. Elliptical Bloch skyrmion chiral twins in an antiskyrmion system. Nat Commun 2020; 11:1115. [PMID: 32111842 PMCID: PMC7048809 DOI: 10.1038/s41467-020-14925-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 02/12/2020] [Indexed: 11/22/2022] Open
Abstract
Skyrmions and antiskyrmions are distinct topological chiral spin textures that have been observed in various material systems depending on the symmetry of the crystal structure. Here we show, using Lorentz transmission electron microscopy, that arrays of skyrmions can be stabilized in a tetragonal inverse Heusler with D2d symmetry whose Dzyaloshinskii-Moriya interaction (DMI) otherwise supports antiskyrmions. These skyrmions can be distinguished from those previously found in several B20 systems which have only one chirality and are circular in shape. We find Bloch-type elliptical skyrmions with opposite chiralities whose major axis is oriented along two specific crystal directions: [010] and [100]. These structures are metastable over a wide temperature range and we show that they are stabilized by long-range dipole-dipole interactions. The possibility of forming two distinct chiral spin textures with opposite topological charges of ±1 in one material makes the family of D2d materials exceptional. Skyrmions and anti-skyrmions often exist in distinct material systems. Here, the authors observe elliptical skyrmions and anti-skyrmions with opposite topological charges in one tetragonal Heusler compound Mn1.4Pt0.9Pd0.1Sn with D2d symmetry.
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Affiliation(s)
- Jagannath Jena
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Börge Göbel
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Tianping Ma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Vivek Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Rana Saha
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Ingrid Mertig
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.,Institute of Physics, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.
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Nagase T, Komatsu M, So YG, Ishida T, Yoshida H, Kawaguchi Y, Tanaka Y, Saitoh K, Ikarashi N, Kuwahara M, Nagao M. Smectic Liquid-Crystalline Structure of Skyrmions in Chiral Magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) Thin Film. PHYSICAL REVIEW LETTERS 2019; 123:137203. [PMID: 31697552 DOI: 10.1103/physrevlett.123.137203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Indexed: 06/10/2023]
Abstract
The organizing of magnetic skyrmions shows several forms similar to atomic arrays of solid states. Using Lorentz transmission electron microscopy, we report the first direct observation of a stable liquid-crystalline structure of skyrmions in chiral magnet Co_{8.5}Zn_{7.5}Mn_{4}(110) thin film, caused by magnetic anisotropy and chiral surface twist. Elongated skyrmions are oriented and periodically arranged only in the ⟨110⟩ directions, whereas they exhibit short-range order along the ⟨001⟩ directions, indicating a smectic skyrmion state. In addition, skyrmions possess anisotropic interaction with an opposite sign depending on the crystal orientation, in contrast to existing isotropic interaction.
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Affiliation(s)
- T Nagase
- Department of Electrical, Electronic Engineering and Information Engineering, School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - M Komatsu
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Y G So
- Department of Materials Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - T Ishida
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - H Yoshida
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - Y Kawaguchi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Y Tanaka
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - K Saitoh
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - N Ikarashi
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - M Kuwahara
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - M Nagao
- Center for Integrated Research of Future Electronics, Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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5
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Peng L, Zhang Y, Ke L, Kim TH, Zheng Q, Yan J, Zhang XG, Gao Y, Wang S, Cai J, Shen B, McQueeney RJ, Kaminski A, Kramer MJ, Zhou L. Relaxation Dynamics of Zero-Field Skyrmions over a Wide Temperature Range. NANO LETTERS 2018; 18:7777-7783. [PMID: 30499678 DOI: 10.1021/acs.nanolett.8b03553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The promise of magnetic skyrmions in future spintronic devices hinges on their topologically enhanced stability and the ability to be manipulated by external fields. The technological advantages of nonvolatile zero-field skyrmion lattice (SkL) are significant if their stability and reliability can be demonstrated over a broad temperature range. Here, we study the relaxation dynamics including the evolution and lifetime of zero-field skyrmions generated from field cooling (FC) in an FeGe single-crystal plate via in situ Lorentz transmission electron microscopy (L-TEM). Three types of dynamic switching between zero-field skyrmions and stripes are identified and distinguished. Moreover, the generation and annihilation of these metastable skyrmions can be tailored during and after FC by varying the magnetic fields and the temperature. This dynamic relaxation behavior under the external fields provides a new understanding of zero-field skyrmions for their stability and reliability in spintronic applications and also raises new questions for theoretical models of skyrmion systems.
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Affiliation(s)
- Licong Peng
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Ying Zhang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Liqin Ke
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Tae-Hoon Kim
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Qiang Zheng
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Jiaqiang Yan
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - X-G Zhang
- Department of Physics and the Quantum Theory Project , University of Florida , Gainesville , Florida 32611 , United States
| | - Yang Gao
- Institute of Advanced Materials , Beijing Normal University , Beijing 100875 , China
| | - Shouguo Wang
- Institute of Advanced Materials , Beijing Normal University , Beijing 100875 , China
| | - Jianwang Cai
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Robert J McQueeney
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Adam Kaminski
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Matthew J Kramer
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
| | - Lin Zhou
- U.S. Department of Energy , Ames Laboratory , Ames , Iowa 50011 , United States
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6
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Yu XZ, Koshibae W, Tokunaga Y, Shibata K, Taguchi Y, Nagaosa N, Tokura Y. Transformation between meron and skyrmion topological spin textures in a chiral magnet. Nature 2018; 564:95-98. [DOI: 10.1038/s41586-018-0745-3] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/11/2018] [Indexed: 11/09/2022]
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7
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Li H, Zhang N, Liu J, Su M, Zeng S, Xu Z. Synthesis and magnetic properties of chiral molecular magnet regulated by terminal coordination groups. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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8
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Karube K, White JS, Morikawa D, Dewhurst CD, Cubitt R, Kikkawa A, Yu X, Tokunaga Y, Arima TH, Rønnow HM, Tokura Y, Taguchi Y. Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet. SCIENCE ADVANCES 2018; 4:eaar7043. [PMID: 30225364 PMCID: PMC6140611 DOI: 10.1126/sciadv.aar7043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 08/03/2018] [Indexed: 05/23/2023]
Abstract
Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with the Dzyaloshinskii-Moriya interaction. Recently, β-Mn structure-type Co-Zn-Mn alloys were identified as a new class of chiral magnet to host such skyrmion crystal phases, while β-Mn itself is known as hosting an elemental geometrically frustrated spin liquid. We report the intermediate composition system Co7Zn7Mn6 to be a unique host of two disconnected, thermal-equilibrium topological skyrmion phases; one is a conventional skyrmion crystal phase stabilized by thermal fluctuations and restricted to exist just below the magnetic transition temperature Tc, and the other is a novel three-dimensionally disordered skyrmion phase that is stable well below Tc. The stability of this new disordered skyrmion phase is due to a cooperative interplay between the chiral magnetism with the Dzyaloshinskii-Moriya interaction and the frustrated magnetism inherent to β-Mn.
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Affiliation(s)
- Kosuke Karube
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Jonathan S. White
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | | | - Charles D. Dewhurst
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Robert Cubitt
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Akiko Kikkawa
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
| | - Yusuke Tokunaga
- Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - Taka-hisa Arima
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - Henrik M. Rønnow
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Bunkyo-ku 113-8656, Japan
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Matsumoto T, So YG, Kohno Y, Ikuhara Y, Shibata N. Stable Magnetic Skyrmion States at Room Temperature Confined to Corrals of Artificial Surface Pits Fabricated by a Focused Electron Beam. NANO LETTERS 2018; 18:754-762. [PMID: 29360375 DOI: 10.1021/acs.nanolett.7b03967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Stable confinement of elemental magnetic nanostructures, such as a single magnetic domain, is fundamental in modern magnetic recording technology. It is well-known that various magnetic textures can be stabilized by geometrical confinement using artificial nanostructures. The magnetic skyrmion, with novel spin texture and promise for future memory devices because of its topological protection and dimension at the nanometer scale, is no exception. So far, skyrmion confinement techniques using large-scale boundaries with limited geometries such as isolated disks and stripes prepared by conventional microfabrication techniques have been used. Here, we demonstrate an alternative technique confining skyrmions to artificial nanostructures (corrals) built from surface pits fabricated by a focused electron beam. Using aberration-corrected differential phase contrast scanning transmission electron microscopy, we directly visualized stable skyrmion states confined at a room temperature to corrals made of artificial surface pits on a thin plate of Co8Zn8Mn4. We observed a stable single-skyrmion state confined to a triangular corral and a unique transition into a triple-skyrmions state depending on the perpendicular magnetic field. Furthermore, we made an array of stable single-skyrmion states by using concatenated triangular corrals. Artificial control of skyrmion states with the present technique should be a powerful way to realize future nonvolatile memory devices using skyrmions.
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Affiliation(s)
- Takao Matsumoto
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo , 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yeong-Gi So
- Department of Materials Science, Graduate School of Engineering Science, Akita University , 1-1 Tegata Gakuen-machi, Akita 010-8502, Japan
| | - Yuji Kohno
- JEOL Limited , 1-2, Musashino 3-chome, Akishima, Tokyo 196-8558, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo , 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center , 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo , 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center , 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
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