Engineering a topological phase transition in β-InSe via strain

Abstract

We report that β-InSe endowed with external strain realizes a novel three dimensional topological insulator (TI) by ab initio calculations. We predicate that the promising topological non-trivial state can be observed in an accessible temperature regime in β-InSe for its large spin–orbital band gap up to 121 meV. Specifically, unlike in previous literature where the band inversion (BI) in TIs is induced using heavy elements that have strong spin–orbital coupling (SOC), we provide a remarkable blueprint for stabilizing BI solely by mechanical deformation so that β-InSe could display BI even without considering SOC. Nevertheless, SOC is still needed to create a band gap at the crossing point by breaking the incompatibility symmetry of the inverted bands.