Prediction of a large-gap and switchable Kane-Mele quantum spin Hall insulator

TL;DR

This paper predicts a new, large-gap, switchable quantum spin Hall insulator based on monolayer Jacutingaite, using first-principles calculations, which could advance topological insulator applications.

Contribution

It introduces a naturally occurring layered mineral as a promising 2D quantum spin Hall insulator with a sizeable band gap, realized through first-principles calculations.

Findings

Proposes monolayer Jacutingaite as a large-gap QSH insulator.

Demonstrates robust helical edge states in the material.

Shows potential for manipulation via spin-orbit coupling and symmetry breaking.

Abstract

Fundamental research and technological applications of topological insulators are hindered by the rarity of materials exhibiting a robust topologically non-trivial phase, especially in two dimensions. Here, by means of extensive first-principles calculations, we propose a novel quantum spin Hall insulator with a sizeable band gap of $\sim$0.5 eV that is a monolayer of Jacutingaite, a naturally occurring layered mineral first discovered in 2008 in Brazil and recently synthesised. This system realises the paradigmatic Kane-Mele model for quantum spin Hall insulators in a potentially exfoliable two-dimensional monolayer, with helical edge states that are robust and that can be manipulated exploiting a unique strong interplay between spin-orbit coupling, crystal-symmetry breaking and dielectric response.