Strain-induced surface modalities in pnictogen chalcogenide topological insulators

We study the role of equi-biaxial strains on the electronic structure in pnictogen chalcogenides Bi₂Se₃, Bi₂Te₃, and As₂Te₃. Bi₂Se₃ and Bi₂Te₃ are topological insulators, and As₂Te₃ is an insulator with a relatively small bandgap. Based on the results of density functional theory calculations including van der Waals corrections, we demonstrate that a topological insulator (TI) state in As₂Te₃ can be induced by an epitaxial (in-plane) tensile misfit strain of 1%. Furthermore, we find overall that the effect of the misfit on the bandgap is larger for As₂Te₃ than for Bi₂Se₃ and Bi₂Te₃. We attribute this to a complex interplay between the misfit strain, spin–orbit coupling, and the relaxation of surface atomic layers. Our findings indicate that As₂Te₃ is more suitable than Bi₂Se₃ and Bi₂Te₃ for potential applications of strain-induced switching of TIs.