# Quantum Anomalous Hall Effect by Coupling Heavy Atomic Layers with CrI$_{3}$

## TL;DR

This paper demonstrates that coupling heavy atomic layers with monolayer CrI$_{3}$ can induce a quantum anomalous Hall effect with sizable gaps and enhanced ferromagnetic properties, opening new avenues for spintronics applications.

## Contribution

It introduces a novel approach of combining heavy-element layers with CrI$_{3}$ to realize quantum anomalous Hall effect and improve magnetic properties.

## Key findings

- CrI$_{3}$/Bi system has a 30 meV bulk gap.
- Heavy atomic layers enhance ferromagnetic properties.
- Spin orientation tuning affects band structure and Fermi level.

## Abstract

We explored the possibility of realizing quantum anomalous Hall effect by placing heavy-element atomic layer on top of monolayer CrI$_{3}$ with a natural cleavage surface and broken time-reversal symmetry. We showed that CrI$_{3}$/X (X = Bi, Sb, or As) systems can open up a sizable bulk gap to harbour quantum anomalous Hall effect, e.g., CrI$_{3}$/Bi is a natural magnetic insulator with a bulk gap of 30~meV, which can be further enlarged via strain engineering or adjusting spin orientations. We also found that the ferromagnetic properties (magnetic anisotropic energy and Curie temperature) of pristine CrI$_{3}$ can be further improved due to the presence of heavy atomic layers, and the spin orientation can be utilized as a useful knob to tune the band structure and Fermi level of CrI$_{3}$/Bi system. The topological nature, together with the enhanced ferromagnetism, can unlock new potential applications for CrI$_{3}$-based materials in spintronics and electronics.