Quantum anomalous Hall effect in ferromagnetic transition metal halides

TL;DR

This paper predicts that RuI3 monolayer is an intrinsic ferromagnetic quantum anomalous Hall insulator with a high Curie temperature, robust topological properties, and potential for room-temperature applications in spintronics.

Contribution

First-principles calculations identify RuI3 monolayer as a new intrinsic QAH insulator with a high Curie temperature and strain-tunable properties.

Findings

RuI3 monolayer exhibits a topologically nontrivial band gap of 11 meV.

The Curie temperature of RuI3 is estimated to be around 360 K.

The QAH effect in RuI3 is robust due to crystal symmetry.

Abstract

The quantum anomalous Hall (QAH) effect is a novel topological spintronic phenomenon arising from inherent magnetization and spin-orbit coupling. Various theoretical and experimental efforts have been devoted in search of robust intrinsic QAH insulators. However, up to now, it has only been observed in Cr or V doped (Bi,Sb)2Te3 film in experiments with very low working temperature. Based on the successful synthesis of transition metal halides, we use first-principles calculations to predict that RuI3 monolayer is an intrinsic ferromagnetic QAH insulator with a topologically nontrivial global band gap of 11 meV. This topologically nontrivial band gap at the Fermi level is due to its crystal symmetry, thus the QAH effect is robust. Its Curie temperature, estimated to be ~360 K using Monte-Carlo simulation, is above room temperature and higher than most of two-dimensional ferromagnetic thin films. We also discuss the manipulation of its exchange energy and nontrivial band gap by applying in-plane strain. Our work adds a new experimentally feasible member to the QAH insulator family, which is expected to have broad applications in nanoelectronics and spintronics.