A complementary screening for quantum spin Hall insulators in 2D exfoliable materials

TL;DR

This study conducts a high-throughput screening of 783 2D exfoliable materials to identify potential quantum spin Hall insulators, discovering new topological insulators and metals that could become such insulators under external perturbations.

Contribution

It introduces a systematic computational approach to identify and predict new quantum spin Hall insulators among 2D materials, expanding the known material candidates.

Findings

Discovered a new $ ext{Z}_2$ topological insulator, HgNS.

Identified 3 known topological insulators.

Found 7 metals that could become QSH insulators with external perturbation.

Abstract

Quantum spin Hall insulators are a class of topological materials that has been extensively studied during the past decade. One of their distinctive features is the presence of a finite band gap in the bulk and gapless, topologically protected edge states that are spin-momentum locked. These materials are characterized by a $\mathbb{Z}_2$ topological order where, in the 2D case, a single topological invariant can be even or odd for a trivial or a topological material, respectively. Thanks to their interesting properties, such as the realization of dissipationless spin currents, spin pumping and spin filtering, they are of great interest in the field of electronics, spintronics and quantum computing. In this work we perform an high-throughput screening of Quantum spin Hall insulators starting from a set of 783 2D exfoliable materials, recently identified from a systematic screening of the ICSD, COD, and MPDS databases. We find a new $\mathbb{Z}_2$ topological insulator (HgNS) as well as 3 already known ones and 7 direect gap metals that have the potential of becoming Quantum spin Hall insulators under a reasonably weak external perturbation.