Topological Phase Transition in Sb 2 Mg 3 Assisted by Strain

Abstract

Topological insulating materials with dissipationless surface states promise potential applications in spintronic materials. Through density functional theory, we proposed a new class of topological phase transition in Sb 2 Mg 3 on the basis of tensile strain. At the equilibrium state, Sb 2 Mg 3 corresponds to a normal insulator, and under the influence of tensile strain, the band gaps are gradually tuned. At ϵ = 7.2%, the nontrivial phase is achieved due to spin-orbital coupling (SOC), and a nontrivial topological phase band gap of 0.22 eV is opened. As a result, the Dirac cone is locked in the bulk, which is associated to p x,y band crossing. Interestingly, the tuning of nontrivial topological properties with tensile strain leading to spin saturation indicates an orbital-filtering effect. The surface state of the Sb 2 Mg 3 material is determined by the topological invariant, Z 2 = 1, at the critical tensile strain in the presence of the SOC effect. This study enhances the scope of topological insulators and current platforms to design new spintronic devices.