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Imaging Domain Reversal in an Ultrathin Van der Waals Ferromagnet |
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| Authors: | David A. Broadway Sam C. Scholten Cheng Tan Nikolai Dontschuk Scott E. Lillie Brett C. Johnson Guolin Zheng Zhenhai Wang Artem R. Oganov Shangjie Tian Chenghe Li Hechang Lei Lan Wang Lloyd C. L. Hollenberg Jean-Philippe Tetienne |
| Affiliation: | 1. School of Physics, University of Melbourne, Parkville, VIC 3010 Australia Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010 Australia Department of Physics, University of Basel, Klingelbergstrasse 82, Basel, CH-4056 Switzerland;2. School of Physics, University of Melbourne, Parkville, VIC 3010 Australia Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, VIC 3010 Australia;3. School of Science, RMIT University, Melbourne, VIC 3000 Australia;4. Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026 Russia School of Telecommunication and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu, 210003 China;5. Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026 Russia Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, Moscow Region, 141700 Russia International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an, 710072 China;6. Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing, 100872 China;7. School of Physics, University of Melbourne, Parkville, VIC 3010 Australia |
| Abstract: | The recent isolation of 2D van der Waals magnetic materials has uncovered rich physics that often differs from the magnetic behavior of their bulk counterparts. However, the microscopic details of fundamental processes such as the initial magnetization or domain reversal, which govern the magnetic hysteresis, remain largely unknown in the ultrathin limit. Here a widefield nitrogen-vacancy (NV) microscope is employed to directly image these processes in few-layer flakes of the magnetic semiconductor vanadium triiodide (VI3). Complete and abrupt switching of most flakes is observed at fields Hc ≈ 0.5–1 T (at 5 K) independent of thickness. The coercive field decreases as the temperature approaches the Curie temperature (Tc ≈ 50 K); however, the switching remains abrupt. The initial magnetization process is then imaged, which reveals thickness-dependent domain wall depinning fields well below Hc. These results point to ultrathin VI3 being a nucleation-type hard ferromagnet, where the coercive field is set by the anisotropy-limited domain wall nucleation field. This work illustrates the power of widefield NV microscopy to investigate magnetization processes in van der Waals ferromagnets, which can be used to elucidate the origin of the hard ferromagnetic properties of other materials and explore field- and current-driven domain wall dynamics. |
| Keywords: | 2D magnetism magnetic domains magnetic imaging nitrogen-vacancy centers van der Waals materials vanadium triiodide |