Critical topology and pressure-induced superconductivity in the van der Waals compound AuTe2Br

TL;DR

This paper predicts that AuTe2Br is a weak topological insulator that maintains its topological properties under pressure and transitions to a superconductor after a structural phase change at around 15.4 GPa, highlighting its potential for topological phases.

Contribution

First-principles calculations identify AuTe2Br as a boundary case between strong and weak topological insulators, revealing pressure-induced topological and superconducting transitions.

Findings

AuTe2Br is at the boundary of strong and weak topological phases.

Pressure up to ~15.4 GPa preserves its topological state.

Superconductivity emerges after a structural phase transition.

Abstract

The study on quantum spin Hall effect and topological insulators formed the prologue to the surge of research activities in topological materials in the past decade. Compared to intricately engineered quantum wells, three-dimensional weak topological insulators provide a natural route to the quantum spin Hall effect, due to the adiabatic connection between them and a stack of quantum spin Hall insulators, and the convenience in exfoliation of samples associated with their van der Waals-type structure. Despite these advantages, both theoretical prediction and experimental identification of weak topological insulators remain scarce. Here, based on first-principles calculations, we show that AuTe2Br locates at the boundary between a strong and a weak topological insulating state. More interestingly, the critical topology of AuTe2Br persists up to an applied pressure of ~ 15.4 GPa before a structural phase transition accompanied by a change of electronic topology and the onset of superconductivity. Our results establish AuTe2Br as a new candidate for weak topological insulators with the potential to realize various other topological phases of matter.