Discovery of a two-dimensional topological insulator in SiTe

TL;DR

This paper predicts that SiTe, a two-dimensional crystal, is a promising topological insulator with a sizeable gap, stability, and tunability, making it suitable for future electronic applications.

Contribution

First-principles calculations identify SiTe as a stable 2D topological insulator with a large nontrivial gap and strain-tunable topological phase transition.

Findings

SiTe has a nontrivial gap of 0.220 eV.

SiTe can be easily exfoliated from bulk material.

Strain engineering can control its topological properties.

Abstract

Two-dimensional (2D) topological insulators (TIs), a new state of quantum matter, are promising for achieving the low-power-consuming electronic devices owning to the remarkable robustness of their conducting edge states against backscattering. Currently, the major challenge to further studies and possible applications is the lack of suitable materials, which should be with high feasibility of fabrication and sizeable nontrivial gaps. Here, we demonstrate through first-principles calculations that SiTe 2D crystal is a promising 2D TI with a sizeable nontrivial gap of 0.220 eV. This material is dynamically and thermally stable. Most importantly, it could be easily exfoliated from its three-dimensional superlattice due to the weakly bonded layered structure. Moreover, strain engineering can effectively control its nontrivial gap and even induce a topological phase transition. Our results provide a realistic candidate for experimental explorations and potential applications of 2D TIs.