Tuning Edge States in Strained-Layer InAs/GaInSb Quantum Spin Hall Insulators

TL;DR

This paper demonstrates enhanced bulk gaps and increased edge velocity in strained-layer InAs/GaInSb quantum wells, revealing robust quantum spin Hall insulator properties protected by time reversal symmetry, suitable for future applications.

Contribution

It introduces strained-layer InAs/GaInSb quantum wells as a new platform with significantly improved properties for quantum spin Hall insulators.

Findings

Bulk gaps increased up to five times compared to InAs/GaSb QSHI.

Edge conductance shows time reversal symmetry protection.

Enhanced edge velocity observed in strained-layer structures.

Abstract

We report on a class of quantum spin Hall insulators (QSHIs) in strained-layer InAs/GaInSb quantum wells, in which the bulk gaps are enhanced by up to five folds as compared to the binary InAs/GaSb QSHI. Remarkably, with consequently increasing edge velocity, the edge conductance at zero and applied magnetic fields manifests time reversal symmetry (TRS) -protected properties consistent with Z2 topological insulator. The InAs/GaInSb bilayers offer a much sought-after platform for future studies and applications of the QSHI.