Anisotropic interactions and strain-induced topological phase transition in Sb2Se3 and Bi2Se3

Based on first-principles calculations, we study the dependence of topological phase on anisotropic interactions in Bi2Se3-type materials. By applying different strains in order to vary interactions, we reveal that the topological phase is insensitive to lateral interaction but can be effectively tuned by longitudinal interaction. Longitudinal strain is inhomogeneous in the studied systems. The interquintuple interaction plays a dominant role in determining the topological phase. We explain the puzzling band-topology difference between Sb2Se3 and Bi2Se3 and propose an approach to tuning the topological phase by strain. It is found that Sb2Se3 can be converted into a topological insulator by applying compressive longitudinal strain while the converse strain can turn Bi2Se3 into a normal insulator. We have studied thin films of Sb2Se3 and Bi2Se3 and also observed a strain-induced topological phase transition.