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arXiv · 2411.18828

Moir\'{e} band theory for M-valley twisted transition metal dichalcogenides

Chao Lei·Perry T. Mahon·Allan H. MacDonald
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Abstract

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 moir\'{e} 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 moir\'e-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 moir\'{e} multilayers.

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Chao Lei, Perry T. Mahon, Allan H. MacDonald. 2024-11-28. Moir\'{e} band theory for M-valley twisted transition metal dichalcogenides. https://doi.org/10.1103/5zt2-scbg

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