Large-Gap Quantum Spin Hall States in Stanene Grown on Substrate

TL;DR

This paper demonstrates that substrate choice critically influences the electronic properties of stanene, enabling the realization of large-gap quantum spin Hall states suitable for room-temperature applications.

Contribution

It reveals that substrate engineering can induce large-gap QSH states in stanene, providing a pathway for practical topological insulator devices.

Findings

Large-gap (up to 0.3 eV) QSH states achievable on specific substrates.

Substrate conditions significantly tune stanene's electronic properties.

Supported stanene can be either trivial or QSH depending on substrate.

Abstract

Two-dimensional stanene is a promising candidate material for realizing room-temperature quantum spin Hall (QSH) effect. Monolayer stanene has recently been fabricated by molecular beam epitaxy, but shows metallic features on Bi$_2$Te$_3$(111) substrate, which motivates us to study the important influence of substrate. Based on first-principles calculations, we find that varying substrate conditions considerably tunes electronic properties of stanene. The supported stanene gives either trivial or QSH states, with significant Rashba splitting induced by inversion asymmetry. More importantly, large-gap (up to 0.3 eV) QSH states are realizable when growing stanene on various substrates, like the anion-terminated (111) surfaces of SrTe, PbTe, BaSe and BaTe. These findings provide significant guidance for future research of stanene and large-gap QSH states.