Two-Dimensional Ferroelastic Topological Insulators in Single-Layer Janus Transition Metal Dichalcogenides MSSe (M=Mo, W)

TL;DR

This paper predicts that Janus single-layer MSSe (M=Mo, W) are stable 2D materials exhibiting both ferroelasticity and quantum spin Hall effects, with potential for nonvolatile memory and spintronic devices.

Contribution

It introduces the first theoretical demonstration of stable 2D ferroelastic topological insulators with sizeable band gaps in Janus MSSe monolayers.

Findings

Janus MSSe monolayers are stable 2D ferroelastic topological insulators.

They exhibit low switching barriers and strong ferroelastic signals.

The materials support the quantum spin Hall effect with sizeable nontrivial band gaps.

Abstract

Two-dimensional topological insulators and two-dimensional materials with ferroelastic characteristics are intriguing materials and many examples have been reported both experimentally and theoretically. Here, we present the combination of both features - a two-dimensional ferroelastic topological insulator that simultaneously possesses ferroelastic and quantum spin Hall characteristics. Using first-principles calculations, we demonstrate Janus single-layer MSSe (M=Mo, W) stable two-dimensional crystals that show the long-sought ferroelastic topological insulator properties. The material features low switching barriers and strong ferroelastic signals, beneficial for applications in nonvolatile memory devices. Moreover, their topological phases harbor sizeable nontrivial band gaps, which supports the quantum spin Hall effect. The unique coexistence of excellent ferroelastic and quantum spin Hall phases in single-layer MSSe provides extraordinary platforms for realizing multi-purpose and controllable devices.