Topological insulating phase arising in transition metal dichalcogenide alloy

TL;DR

This study predicts a topological insulator phase in Pt(HgxSe1-x)2 alloys, showing a transition at low Hg concentration and highlighting the potential for discovering non-trivial topological phases in random alloy systems.

Contribution

It introduces a new topological phase in transition metal dichalcogenide alloys and identifies the alloy concentration threshold for the topological transition using ab-initio calculations.

Findings

Topological phase appears at 9% Hg alloy concentration.

The topological transition depends on alloy concentration and Hg distribution.

The results suggest new avenues for exploring topological phases in alloy systems.

Abstract

Transition metal dichalcogenides have been the subject of numerous studies addressing technological applications and fundamental issues. Single-layer PtSe2 is a semiconductor with a trivial bandgap, in contrast, its counterpart with 25% of Se atoms substituted by Hg, Pt2HgSe3 (jacutingaite, a naturally occurring mineral), is a 2D topological insulator with a large bandgap. Based on ab-initio calculations, we investigate the energetic stability, and the topological transition in Pt(HgxSe1-x)2 as a function of alloy concentration, and the distribution of Hg atoms embedded in the PtSe2 host. Our findings reveal the dependence of the topological phase with respect to the alloy concentration and robustness with respect distribution of Hg. Through a combination of our ab-initio results and a defect wave function percolation model, we estimate the random alloy concentration threshold for the topological transition to be only 9%. Our results expand the possible search for non-trivial topological phases in random alloy systems.