# Magnetic Exchange Mechanism and Quantized Anomalous Hall Effect in Bi2Se3 Film with a CrWI6 Monolayer

## TL;DR

This paper explores how to magnetize topological insulators without destroying their properties, aiming to achieve the quantum anomalous Hall effect.

## Contribution

The study introduces a 2D magnetic semiconductor, CrWI6, that effectively magnetizes topological surface states via the magnetic proximity effect.

## Key findings

- A non-trivial phase was identified in Bi2Se3 films with six quantum layers within the CrWI6/BS/CrWI6 heterostructure.
- Adjusting the interface distance increased the non-trivial band gap from 2.9 meV to 7.9 meV, aiding the QAH effect realization.
- The topological non-triviality was confirmed by a nonzero Chern number in the CrWI6/6QL-BS/CrWI6 system.

## Abstract

Magnetizing the surface states of topological insulators without damaging their topological features is a crucial step for realizing the quantum anomalous Hall (QAH) effect and remains a challenging task. The TI–ferromagnetic material interface system was constructed and studied by the density functional theory (DFT). A two-dimensional magnetic semiconductor CrWI6 has been proven to effectively magnetize topological surface states (TSSs) via the magnetic proximity effect. The non-trivial phase was identified in the Bi2Se3 (BS) films with six quantum layers (QL) within the CrWI6/BS/CrWI6 heterostructure. BS thin films exhibit the generation of spin splitting near the TSSs, and a band gap of approximately 2.9 meV is observed at the Γ in the Brillouin zone; by adjusting the interface distance of the heterostructure, we increased the non-trivial band gap to 7.9 meV, indicating that applying external pressure is conducive to realizing the QAH effect. Furthermore, the topological non-triviality of CrWI6/6QL-BS/CrWI6 is confirmed by the nonzero Chern number. This study furnishes a valuable guideline for the implementation of the QAH effect at elevated temperatures within heterostructures comprising two-dimensional (2D) magnetic monolayers (MLs) and topological insulators.