Two-Dimensional Oxide Topological Insulator With Iron-Pnictide Superconductor LiFeAs Structure

TL;DR

This paper predicts a stable 2D oxide topological insulator, ZrSiO, with potential for room-temperature topotronic devices and possible integration with superconductors like LiFeAs to realize novel quantum phenomena.

Contribution

It introduces ZrSiO as a new 2D oxide topological insulator with a sizable band gap and explores its structural similarity to LiFeAs, opening pathways for topological superconductor research.

Findings

ZrSiO is a dynamically stable 2D oxide TI with a 30 meV band gap.

ZrSiO's structure is similar to LiFeAs, a superconductor.

Multiple isostructural compounds with similar electronic properties are identified.

Abstract

By using first-principles calculations, we propose that ZrSiO can be looked as a three-dimensional (3D) oxide weak topological insulator (TI) and its single layer is a long-sought-after 2D oxide TI with a band gap up to 30 meV. Calculated phonon spectrum of the single layer ZrSiO indicates it is dynamically stable and the experimental achievements in growing oxides with atomic precision ensure that it can be readily synthesized. This will lead to novel devices based on TIs, the so called "topotronic" devices, operating under room-temperature and stable when exposed in the air. Thus, a new field of "topotronics" will arise. Another intriguing thing is this oxide 2D TI has the similar crystal structure as the well-known iron-pnictide superconductor LiFeAs. This brings great promise in realizing the combination of superconductor and TI, paving the way to various extraordinary quantum phenomena, such as topological superconductor and Majorana modes. We further find that there are many other isostructural compounds hosting the similar electronic structure and forming a $WHM$-family with $W$ being Zr, Hf or La, $H$ being group IV or group V element, and $M$ being group VI one.