Pressure-induced Topological Phase Transitions in Rock-salt Chalcogenides

TL;DR

This paper demonstrates through theoretical and computational methods that applying pressure to rock-salt chalcogenides can induce topological phase transitions, revealing new ways to manipulate topological states in these materials.

Contribution

It identifies the microscopic conditions and specific materials in the rock-salt chalcogenide class that can undergo pressure-induced topological phase transitions, supported by first-principles calculations.

Findings

Pressure can induce topological phase transitions in rock-salt chalcogenides.

Band inversions are caused by asymmetric hybridization of orbitals.

Materials prone to topological transitions are identified.

Abstract

By means of a comprehensive theoretical investigation, we show that external pressure can induce topological phase transitions in IV-VI semiconducting chalcogenides with rock-salt structure. These materials satisfy mirror symmetries that are needed to sustain topologically protected surface states, at variance with time-reversal symmetry responsible for gapless edge states in $\mathcal{Z}_{2}$ topological insulators. The band inversions at high-symmetry points in the Brillouin zone that are related by mirror symmetry, are brought about by an "asymmetric" hybridization between cation and anion $sp$ orbitals. By working out the microscopic conditions to be fulfilled in order to maximize this hybridization, we identify materials in the rock-salt chalcogenide class that are prone to undergo a topological phase transition induced by pressure and/or alloying. Our model analysis is fully comfirmed by complementary advanced \textit{first-principles} calculations and \textit{ab initio}-based tight-binding simulations.