Layer-dependent topological surface states in BiSb

Abstract

The emergence of topological materials has changed the understanding of their electronic and magnetic properties. This work investigated the structural and electronic properties of bulk and a few layers of BiSb material. Interestingly, only the bulk and monolayer systems present semiconductor characteristics. From two monolayers onwards, a semi-metallic character is found. This semi-metallic behavior is due to valance and conduction bands crossing the Fermi level near the Γ point. These band crossings are related to topological surface states, which are achieved without inducing strain into the system, contrary to their bulk and monolayer counterparts. Defects, like deformations, vacancies, or doping, are expected not to affect the surface states. As a probe of concept, the biaxial strain was induced in BiSb surfaces, making no changes in the surface states. These robust surface states are desirable for constructing magnetic-topological junctions for new-generation solid-state storage applications.