Single-Dirac-Cone topological surface states in TlBiSe2 class of Topological Insulators

TL;DR

This paper predicts that certain TlBiSe2 class materials are topological insulators with a single Dirac cone surface state, supported by first-principles calculations, and suggests their potential for quantum spin Hall and topological superconductivity applications.

Contribution

It identifies the specific surface termination that reveals the single Dirac cone in TlBiSe2 class materials using first-principles calculations.

Findings

Predicted topologically nontrivial surface states in TlBiTe2, TlBiSe2, and TlSbX2.

Identified surface termination favorable for ARPES experiments.

Suggested thin films could host 2D quantum spin Hall states and topological superconductivity.

Abstract

We have investigated several strong spin-orbit coupling ternary chalcogenides related to the (Pb,Sn)Te series of compounds. Our first-principles calculations predict the low temperature rhombohedral ordered phase in TlBiTe2, TlBiSe2, and TlSbX2 (X=Te, Se, S) to be topologically Kane-Mele Z2 = -1 nontrivial. We identify the specific surface termination that realizes the single Dirac cone through first-principles surface state computations. This termination minimizes effects of dangling bonds making it favorable for photoemission (ARPES) experiments. Our analysis predicts that thin films of these materials would harbor novel 2D quantum spin Hall states, and support odd-parity topological superconductivity. For a related work also see arXiv:1003.2615v1. Experimental ARPES results will be published elsewhere.