Strain induced Z2 topological insulating state of β-As2Te3

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: R3¯m) of As2Te3 (β-As2Te3) through first-principles calculations including spin-orbit coupling within density functional theory. The ETT in β-As2Te3 is shown to occur at the uniaxial strain ϵzz = −0.05 (σzz = 1.77 GPa), passing through a Weyl metallic state with a single Dirac cone in its electronic structure at the Γ 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 ℤ2 topological invariant ν0 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 us...