Topological Insulators at Room Temperature

TL;DR

This paper predicts and analyzes topological insulators like Bi2Se3 that have robust surface states and a sizable energy gap suitable for room temperature applications, using first-principle calculations and a continuum model.

Contribution

It identifies specific materials as topological insulators with a non-trivial energy gap and introduces a simple continuum model capturing their key topological features.

Findings

Bi2Se3 has a 0.3 eV energy gap suitable for room temperature.

Sb2Te3, Bi2Te3, and Bi2Se3 are topological insulators.

Sb2Se3 is not a topological insulator.

Abstract

Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for $Sb_2Te_3$, $Sb_2Se_3$, $Bi_2Te_3$ and $Bi_2Se_3$ crystals. Our calculations predict that $Sb_2Te_3$, $Bi_2Te_3$ and $Bi_2Se_3$ are topological insulators, while $Sb_2Se_3$ is not. In particular, $Bi_2Se_3$ has a topologically non-trivial energy gap of $0.3 eV$, suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the $\Gamma$ point.