Strain induced Z(2) topological insulating state of beta-As2Te3

Abstract

Topological insulators are non-trivial quantum states of matter which exhibit a gap in the electronic structure of their bulk form, but a gapless metallic electronic spectrum at the surface. Here, we predict a uniaxial strain induced electronic topological transition (ETT) from a band to topological insulating state in the rhombohedral phase (space group: R (3) over barm) of As2Te3 (beta-As2Te3) through first-principles calculations including spin-orbit coupling within density functional theory. The ETT in beta-As2Te3 is shown to occur at the uniaxial strain epsilon(zz) = -0.05 (sigma(zz) = 1.77 GPa), passing through a Weyl metallic state with a single Dirac cone in its electronic structure at the Gamma point. We demonstrate the ETT through band inversion and reversal of parity of the top of the valence and bottom of the conduction bands leading to change in the Z(2) topological invariant nu(0) from 0 to 1 across the transition. Based on its electronic structure and phonon dispersion, we propose ultra-thin films of As2Te3 to be promising for use in ultra-thin stress sensors, charge pumps, and thermoelectrics. (C) 2014 AIP Publishing LLC.