# Topological Phase Transition in Two-Dimensional Magnetic Material CrI3 Bilayer Intercalated with Mo

## TL;DR

This paper shows that adding Mo to a CrI3 bilayer creates a magnetic material with tunable topological properties useful for spintronics.

## Contribution

The study reveals that Mo-intercalated CrI3 bilayer exhibits a topological phase transition controllable by external magnetic fields.

## Key findings

- Mo-intercalated CrI3 bilayer shows ferromagnetic semiconductor behavior with small easy-plane magnetocrystalline anisotropy energy.
- Spin–orbit coupling opens a band gap enabling quantum anomalous Hall effect in one magnetization orientation.
- The material's topological properties can be manipulated efficiently with an external magnetic field.

## Abstract

Motivated by the seminal discoveries in graphene, the exploration of novel physical phenomena in alternative two-dimensional (2D) materials has attracted tremendous attention. In this work, through theoretical investigation using first-principles calculations, we reveal that Mo-intercalated CrI3 bilayer exhibits ferromagnetic semiconductor behavior with a small easy-plane magnetocrystalline anisotropy energy (MAE) of 0.618 meV/Cr(Mo) between (100) and (001) magnetizations. The spin–orbit coupling (SOC) opens a narrow band gap at the Fermi level for both magnetization orientations with nonzero Chern number for realizing the quantum anomalous Hall effect (QAHE) in the former and with trivial topology in the latter. The small MAE implies the efficient experimental manipulation of magnetization between distinct topologies through an external magnetic field. Our findings provide compelling evidence that the QAHE in this system originates from the quantum spin Hall effect (QSHE), driven by intrinsic magnetism under broken time-reversal symmetry. These unique properties position Mo-intercalated CrI3 as a promising candidate for tunable spintronic applications.