Topological phase in non-centrosymmetric material NaSnBi

TL;DR

This paper predicts that NaSnBi is a three-dimensional topological insulator with unique surface states, driven by Rashba spin-orbit coupling, as revealed through first-principle calculations and effective modeling.

Contribution

It identifies NaSnBi as a non-centrosymmetric topological phase and elucidates the role of Rashba coupling in its topological transition, highlighting novel surface state characteristics.

Findings

NaSnBi is a 3D non-trivial topological insulator.

Topological phase transition driven by Rashba spin-orbit coupling.

Surface states exhibit right-handed spin texture and termination-dependent features.

Abstract

We predict that a non-centrosymmetric material NaSnBi locates in a three-dimensional non-trivial topological phase under ambient pressure based on first-principle calculations. By deriving the effective model around $\Gamma$ point, we find that the topological phase transition is driven by a Rashba spin-orbital coupling through an odd number of pairs of band touch because of a small anisotropic gap caused by quintic dispersion terms. In contrast to conventional topological insulators, the spin texture of surface Dirac cone is right-handed and the surface states are strikingly different for different surface terminations.