Symmetric Wannier states and tight-binding model for quantum spin Hall bands in AB-stacked MoTe$_2$/WSe$_2$

TL;DR

This paper develops a symmetry-adapted Wannier states and tight-binding model for quantum spin Hall bands in AB-stacked MoTe2/WSe2, capturing topological properties and phase transitions based on first-principles data.

Contribution

It introduces a novel tight-binding model on a triangular lattice that accurately describes topological states in AB-stacked MoTe2/WSe2, including phase transitions.

Findings

Tight-binding model reproduces energy spectrum and topological phase transition.

Two Wannier states per valley with same center but different angular momenta.

Model parameters derived from first-principles calculations.

Abstract

Motivated by the observation of topological states in AB-stacked MoTe$_2$/WSe$_2$, we construct the symmetry-adapted Wannier states and tight-binding model for the quantum spin Hall bands in this system. Our construction is based on the symmetry analysis of Bloch states obtained from the continuum moir\'e Hamiltonian. For model parameters extracted from first-principles calculations, we find that the quantum spin Hall bands can be described by a tight-binding model defined on a triangular lattice. There are two Wannier states per valley, which have the same Wannier center but different angular momenta under threefold rotation. The tight-binding model not only reproduces the energy spectrum, but also accurately describes the topological phase transition induced by the out-of-plane displacement field. Our study sheds new light on the topological states in moir\'e transition metal dichalcogenides bilayers, and provides a route to addressing the many-body physics in AB-stacked MoTe$_2$/WSe$_2$.