Topological Origin of Intrinsic High Chern Numbers in Two-Dimensional M$_2$X$_2$ Materials
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| Format: | Preprint |
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2025
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| _version_ | 1866909775591112704 |
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| author | Dai, Zujian Zhu, Xudong He, Lixin |
| author_facet | Dai, Zujian Zhu, Xudong He, Lixin |
| contents | Despite sharing a common lattice structure, monolayer M$_2$X$_2$ compounds realize quantum anomalous Hall phases with distinct Chern numbers, a striking phenomenon that has not been fully exploared. Combining first-principles calculations with symmetry analysis and tight-binding models, we identify two generic band-inversion mechanisms governed by the orbital composition and symmetry representations of 3$d$ states near the Fermi level. When $d_{xz}/d_{yz}$ orbtials dominate, a doubly degenerate $Γ$-point inversion yields $C=1$; otherwise, inversions occur along $Γ$-X and $Γ$-Y at four $C_4$-related momenta, whose Berry-curvature contributions add to give $C=2$, distinct from scenarios relying on multiple bands inversions at a single $\mathbf{k}$ point. The same mechanism consistently explains related two-dimensional systems, including LiFeSe, KTiSb, MgFeP, and Janus M$_2$X$_2$ derivatives. The mechanism provide practical guidance for screening and engineering tunable high-Chern-number insulators. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_06288 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Topological Origin of Intrinsic High Chern Numbers in Two-Dimensional M$_2$X$_2$ Materials Dai, Zujian Zhu, Xudong He, Lixin Materials Science Despite sharing a common lattice structure, monolayer M$_2$X$_2$ compounds realize quantum anomalous Hall phases with distinct Chern numbers, a striking phenomenon that has not been fully exploared. Combining first-principles calculations with symmetry analysis and tight-binding models, we identify two generic band-inversion mechanisms governed by the orbital composition and symmetry representations of 3$d$ states near the Fermi level. When $d_{xz}/d_{yz}$ orbtials dominate, a doubly degenerate $Γ$-point inversion yields $C=1$; otherwise, inversions occur along $Γ$-X and $Γ$-Y at four $C_4$-related momenta, whose Berry-curvature contributions add to give $C=2$, distinct from scenarios relying on multiple bands inversions at a single $\mathbf{k}$ point. The same mechanism consistently explains related two-dimensional systems, including LiFeSe, KTiSb, MgFeP, and Janus M$_2$X$_2$ derivatives. The mechanism provide practical guidance for screening and engineering tunable high-Chern-number insulators. |
| title | Topological Origin of Intrinsic High Chern Numbers in Two-Dimensional M$_2$X$_2$ Materials |
| topic | Materials Science |
| url | https://arxiv.org/abs/2509.06288 |