Quantum Spin Hall Effect with Extended Topologically Protected Features in Altermangetic Multilayers
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866909731866542080 |
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| author | Chen, Zhiyu Zhan, Fangyang Qin, Zheng Ma, Da-Shuai Xu, Dong-Hui Wang, Rui |
| author_facet | Chen, Zhiyu Zhan, Fangyang Qin, Zheng Ma, Da-Shuai Xu, Dong-Hui Wang, Rui |
| contents | Conventional topological classification theory dictates that time-reversal symmetry confines the quantum spin Hall (QSH) effect to a $\mathbb{Z}_2$ classification, permitting only a single pair of gapless helical edge states. Here, we utilize the recently discovered altermagnetism to circumvent this fundamental constraint. We demonstrate the realization of a unique QSH phase possessing multiple pairs of gapless helical edge states in altermagnetic multilayers. This exotic QSH phase, characterized by a mirror-spin Chern number, emerges from the interplay of spin-orbit coupling and $d$-wave altermagnetic ordering. Moreover, using first-principles calculations, we identify altermagnetic Fe$_2$Se$_2$O multilayers as promising material candidates, in which the number of gapless helical edge states scales linearly with the number of layers, leading to a correspondingly large, exactly quantized, and experimentally accessible spin-Hall conductance. Our findings unveil a new mechanism for stabilizing multiple pairs of gapless helical edge states, significantly expanding the scope of QSH effects, and provide a blueprint for utilizing altermagnetism to engineer desired topological phases. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_03580 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Quantum Spin Hall Effect with Extended Topologically Protected Features in Altermangetic Multilayers Chen, Zhiyu Zhan, Fangyang Qin, Zheng Ma, Da-Shuai Xu, Dong-Hui Wang, Rui Mesoscale and Nanoscale Physics Materials Science Conventional topological classification theory dictates that time-reversal symmetry confines the quantum spin Hall (QSH) effect to a $\mathbb{Z}_2$ classification, permitting only a single pair of gapless helical edge states. Here, we utilize the recently discovered altermagnetism to circumvent this fundamental constraint. We demonstrate the realization of a unique QSH phase possessing multiple pairs of gapless helical edge states in altermagnetic multilayers. This exotic QSH phase, characterized by a mirror-spin Chern number, emerges from the interplay of spin-orbit coupling and $d$-wave altermagnetic ordering. Moreover, using first-principles calculations, we identify altermagnetic Fe$_2$Se$_2$O multilayers as promising material candidates, in which the number of gapless helical edge states scales linearly with the number of layers, leading to a correspondingly large, exactly quantized, and experimentally accessible spin-Hall conductance. Our findings unveil a new mechanism for stabilizing multiple pairs of gapless helical edge states, significantly expanding the scope of QSH effects, and provide a blueprint for utilizing altermagnetism to engineer desired topological phases. |
| title | Quantum Spin Hall Effect with Extended Topologically Protected Features in Altermangetic Multilayers |
| topic | Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2508.03580 |