Magnetic Second-Order Topological Insulator: An Experimentally Feasible 2D CrSiTe3 |
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Authors: | Xiaotian Wang Xiao-Ping Li Jianghua Li Chengwu Xie Jianhua Wang Hongkuan Yuan Wenhong Wang Zhenxiang Cheng Zhi-Ming Yu Gang Zhang |
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Affiliation: | 1. School of Physical Science and Technology, Southwest University, Chongqing, 400715 China;2. School of Physical Science and Technology, Inner Mongolia University, Hohhot, 010021 China;3. School of Electronics & Information Engineering, Tiangong University, Tianjin, 300387 China;4. Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, Wollongong, 2500 Australia;5. Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081 China;6. Institute of High Performance Computing, Agency for Science, Technology and Research (A*STAR), Singapore, 138632 Singapore |
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Abstract: | 2D second-order topological insulators (SOTIs) have sparked significant interest, but currently, the proposed realistic 2D materials for SOTIs are limited to nonmagnetic systems. In this study, for the first time, a single layer of chalcogenide CrSiTe3—an experimentally realized transition metal trichalcogenide is proposed with a layer structure—as a 2D ferromagnetic (FM) SOTI. Based on first-principles calculations, this study confirms that the CrSiTe3 monolayer exhibits a nontrivial gapped bulk state in the spin-up channel and a trivial gapped bulk state in the spin-down channel. Based on the higher-order bulk–boundary correspondence, it demonstrates that the CrSiTe3 monolayer exhibits topologically protected corner states with a quantized fractional charge () in the spin-up channel. Notably, unlike previous nonmagnetic examples, the topological corner states of the CrSiTe3 monolayer are spin-polarized and pinned at the corners of the sample in real space. Furthermore, the CrSiTe3 monolayer retains SOTI features when the spin–orbit coupling (SOC) is considered, as evidenced by the corner charge and corner states distribution. Finally, by applying biaxial strain and hole doping, this study transforms the magnetic insulating bulk states into spin-gapless semiconducting and half-metallic bulk states, respectively. Importantly, the topological corner states persist in the spin-up channel under these conditions. |
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Keywords: | corner states higher-order topological insulators magnetic materials transition metal trichacogenides |
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