Strong magnetization and Chern insulators in compressed graphene/CrI$_{3}$ van der Waals heterostructures

TL;DR

This study predicts that compressing graphene/CrI3 heterostructures induces a Chern insulating state with strong magnetization, potentially enabling high-temperature quantum anomalous Hall effect observations.

Contribution

First-principles calculations reveal that pressure-induced compression of graphene/CrI3 heterostructures creates a Chern insulator with strong magnetization, advancing topological material design.

Findings

Chern insulating state achieved under specific compression

Strong magnetization (~150 meV) induced in graphene

Potential to observe quantum anomalous Hall effect at 45 K

Abstract

Graphene-based heterostructures are a promising material system for designing the topologically nontrivial Chern insulating devices. Recently, a two-dimensional (2D) monolayer ferromagnetic insulator CrI$_{3}$ was successfully synthesized in experiments [Huang et al., Nature 546, 270 (2017)]. Here, these two interesting materials are proposed to build a heterostructure (Gr/CrI$_{3}$). Our first-principles calculations show that the system forms a van der Waals (vdW) heterostructure, relatively facilely fabricated in experiments. A Chern insulating state is acquired in the Gr/CrI$_{3}$ heterostructure if the vdW gap is compressed to certain extents by applying an external pressure. Amazingly, very strong magnetization (about 150 meV) is found in graphene, induced by the substrate CrI$_{3}$, despite the vdW interactions between them. A low-energy effective model is employed to understand the mechanism. The work functions, contact types, and band alignments of the Gr/CrI$_{3}$ heterostructure system are also studied. Our work demonstrates that the Gr/CrI$_{3}$ heterostructure is a promising system to observe the quantum anomalous Hall effect at high temperatures (up to 45 K) in experiments.