Quantum spin Hall effect in monolayer and bilayer TaIrTe$_{4}$

TL;DR

This study uses first-principles calculations to demonstrate that monolayer and bilayer TaIrTe$_{4}$ are quantum spin Hall insulators, revealing a topological phase transition influenced by interlayer interactions.

Contribution

It is the first to show bilayer TaIrTe$_{4}$ as a quantum spin Hall insulator and explores the topological phase transition driven by interlayer distance.

Findings

Monolayer TaIrTe$_{4}$ is a quantum spin Hall insulator.

Bilayer TaIrTe$_{4}$ also exhibits quantum spin Hall phase.

A topological phase transition occurs with changing interlayer distance.

Abstract

Generally, stacking two quantum spin Hall insulators gives rise to a trivial insulator. Here, based on first-principles electronic structure calculations, we confirm that monolayer TaIrTe$_{4}$ is a quantum spin Hall insulator and remarkably find that bilayer TaIrTe$_{4}$ is still a quantum spin Hall insulator. Theoretical analysis indicates that the covalent-like interlayer interaction in combination with the small bandgap at time-reversal invariant $\Gamma$ point results in new band inversion in bilayer TaIrTe$_{4}$, namely, the emergence of quantum spin Hall phase. Meanwhile, a topological phase transition can be observed by increasing the interlayer distance in bilayer TaIrTe$_{4}$. Considering that bulk TaIrTe$_{4}$ is a type-II Weyl semimetal, layered TaIrTe$_{4}$ thus provides an ideal platform to realize different topological phases at different dimensions.