Controllable chirality and band gap of quantum anomalous Hall insulators

TL;DR

This study develops a comprehensive first-principles database of quantum anomalous Hall insulators, revealing key mechanisms like Coulomb exchange and proposing strategies for property control to advance magnetic topological materials.

Contribution

It introduces a first-principles database of QAH materials, uncovers the role of Coulomb exchange, and suggests design strategies for tuning chirality and band gap.

Findings

Coulomb exchange is unexpectedly strong in many QAH materials.

Simple indicators for property evaluation are identified.

Material design strategies for controlling QAH properties are proposed.

Abstract

Finding guiding principles to optimize properties of quantum anomalous Hall (QAH) insulators is of pivotal importance to fundamental science and applications. Here, we build a first-principles QAH material database of chirality and band gap, explore microscopic mechanisms determining the QAH material properties, and obtain a general physical picture that can comprehensively understand the QAH data. Our results reveal that the usually neglected Coulomb exchange is unexpectedly strong in a large class of QAH materials, which is the key to resolve experimental puzzles. Moreover, we identify simple indicators for property evaluation and suggest material design strategies to control QAH chirality and gap by tuning cooperative or competing contributions via magnetic co-doping, heterostructuring, spin-orbit proximity, etc. The work is valuable to future research of magnetic topological physics and materials.