Robust Room-Temperature Quantum Spin Hall Effect in Methyl-functionalized InBi honeycomb film

TL;DR

This paper predicts that methyl-functionalized InBi monolayer exhibits a robust quantum spin Hall effect with a large band gap suitable for room-temperature applications, confirmed by first-principles calculations.

Contribution

It introduces a new methyl-functionalized InBi monolayer with a large, tunable QSH gap, stable at room temperature, and compatible with substrates, advancing 2D topological insulator research.

Findings

InBiCH3 has a band gap of 0.29 eV suitable for room temperature.

The QSH state is robust against strain, electric field, and methyl coverage.

Supported on h-BN, it maintains a nontrivial topological state.

Abstract

Two-dimensional (2D) group-III-V honeycomb films have attracted significant interest for their potential application in fields of quantum computing and nanoeletronics. Searching for 2D III-V films with high structural stability and large-gap are crucial for the realizations of dissipationless transport edge states using quantum spin Hall (QSH) effect. Based on first-principles calculations, we predict that the methyl-functionalized InBi monolayer (InBiCH3) has no dynamic instability, and host a QSH state with a band gap as large as 0.29 eV, exhibiting an interesting electronic behavior viable for room-temperature applications. The topological characteristic is confirmed by s-pxy bands inversion, topological invariant Z2 number, and the time-reversal symmetry protected helical edge states. Noticeably, the QSH states are tunable and robust against the mechanical strain, electric field and different levels of methyl coverages. We also find that InBiCH3 supported on h-BN substrate maintains a nontrivial QSH state, which harbors the edge states lying within the band gap of substrate. These findings demonstrate that the methyl-functionalized III-V films may be a good QSH platform for device design and fabrication in spintronics.