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arXiv · 2106.06058

Multifaceted moiré superlattice physics in twisted WSe$_2$ bilayers

S. J. Magorrian·V. V. Enaldiev·V. Zólyomi·Fábio Ferreira·Vladimir I. Fal'ko·David A. Ruiz-Tijerina
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Abstract

Lattice reconstruction in twisted transition-metal dichalcogenide (TMD) bilayers gives rise to piezo- and ferroelectric moiré potentials for electrons and holes, as well as a modulation of the hybridisation across the bilayer. Here, we develop hybrid $\mathbf{k}\cdot \mathbf{p}$ tight-binding models to describe electrons and holes in the relevant valleys of twisted TMD homobilayers with parallel (P) and anti-parallel (AP) orientations of the monolayer unit cells. We apply these models to describe moiré superlattice effects in twisted WSe${}_2$ bilayers, in conjunction with microscopic \emph{ab initio} calculations, and considering the influence of encapsulation, pressure and an electric displacement field. Our analysis takes into account mesoscale lattice relaxation, interlayer hybridisation, piezopotentials, and a weak ferroelectric charge transfer between the layers, and describes a multitude of possibilities offered by this system, depending on the choices of P or AP orientation, twist angle magnitude, and electron/hole valley.

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S. J. Magorrian, V. V. Enaldiev, V. Zólyomi, Fábio Ferreira, Vladimir I. Fal'ko, David A. Ruiz-Tijerina. 2021-09-28. Multifaceted moiré superlattice physics in twisted WSe$_2$ bilayers. https://doi.org/10.1103/physrevb.104.125440

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