# First-principles prediction of a new family of layered topological insulators

## TL;DR

This paper uses first-principles calculations to predict a new family of layered topological insulators and metals among V$_2$IV$_2$VI$_6$ compounds, expanding the potential materials for spintronic applications.

## Contribution

It predicts nine strong topological insulators and two topological metals in a family of layered compounds, many of which can be experimentally synthesized.

## Key findings

- Nine strong topological insulators predicted with energy gaps 0.04-0.2 eV.
- Small strains can convert trivial insulators into topological insulators.
- Several compounds are already synthesized, facilitating experimental validation.

## Abstract

Dozens of layered V$_2$IV$_2$VI$_6$ (V=P, As, Sb, Bi, IV=Si, Ge, Sn, Pb, VI=S, Se, Te) materials are investigated, several of which have been successfully synthesized in experiment. Among them, we predict nine strong topological insulators (TIs), two strong topological metals (TMs) and nearly twenty trivial insulators at their equilibrium structures. The TIs are in the (1;111) topological class, with energy gaps ranging from 0.04 to 0.2 eV. The strong TMs and the trivial insulators belong to the (1;111) and (0;000) topological classes, respectively. Small compressive strains easily turn some of the trivial insulators into strong TIs. This study enriches not only the family of topological materials but also the family of van der Waals layered materials, providing promising candidates for the future spintronic devices.