Moiré band theory for M-valley twisted transition metal dichalcogenides
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| Format: | Preprint |
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2024
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| _version_ | 1866909890336784384 |
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| author | Lei, Chao Mahon, Perry T. MacDonald, Allan H. |
| author_facet | Lei, Chao Mahon, Perry T. MacDonald, Allan H. |
| contents | We propose twisted bilayers of certain group IV and IVB trigonal transition metal dichalcogenides (TMDs) MX$_{2}$ (M$=$Zr, Hf, Sn and X$=$S, Se) as moiré materials. In monolayer form these TMDs have conduction band minima near the three inequivalent Brillouin zone $M$ points and negligible spin-orbit coupling, implying six flavors of low-energy conduction band states. The flavor sectors decouple at the single-particle level and in twisted bilayers are accurately described by emergent moiré-periodic Hamiltonians that we derive from small-unit-cell density functional theory calculations. Because the valley-projected Hamiltonians have large valley-dependent mass anisotropies and are time-reversal invariant, spontaneous valley polarization is signaled in transport by anisotropy instead of by the anomalous Hall and magnetic circular dichroism signals commonly observed in graphene and $K$-valley TMD-based moiré multilayers. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_18828 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Moiré band theory for M-valley twisted transition metal dichalcogenides Lei, Chao Mahon, Perry T. MacDonald, Allan H. Mesoscale and Nanoscale Physics We propose twisted bilayers of certain group IV and IVB trigonal transition metal dichalcogenides (TMDs) MX$_{2}$ (M$=$Zr, Hf, Sn and X$=$S, Se) as moiré materials. In monolayer form these TMDs have conduction band minima near the three inequivalent Brillouin zone $M$ points and negligible spin-orbit coupling, implying six flavors of low-energy conduction band states. The flavor sectors decouple at the single-particle level and in twisted bilayers are accurately described by emergent moiré-periodic Hamiltonians that we derive from small-unit-cell density functional theory calculations. Because the valley-projected Hamiltonians have large valley-dependent mass anisotropies and are time-reversal invariant, spontaneous valley polarization is signaled in transport by anisotropy instead of by the anomalous Hall and magnetic circular dichroism signals commonly observed in graphene and $K$-valley TMD-based moiré multilayers. |
| title | Moiré band theory for M-valley twisted transition metal dichalcogenides |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2411.18828 |