Atomic scale quantum anomalous hall effect in monolayer graphene/MnBi₂Te₄ heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Physics

Background:

• The two-dimensional quantum anomalous Hall (QAH) effect signifies non-trivial Berry curvature topology.
• Discovering QAH in 2D materials with simplified fabrication is crucial for applications.
• Previous theoretical QAH studies in graphene often overlooked essential magnetism sources like substrate effects.

Purpose of the Study:

• To propose and investigate the QAH effect in graphene/MnBi2Te4 (MBT) heterostructures.
• To explore novel magnetic topological phases enabled by MBT family materials.

Main Methods:

• Density-functional theory (DFT) calculations were employed to model the graphene/MBT heterostructure.
• An effective Hamiltonian was developed to analyze the system's topological properties and phase diagram.

Main Results:

• The monolayer MBT substrate effectively induces spin-orbital coupling, a Zeeman exchange field, and Kekulé distortion in graphene.
• These combined effects lead to the emergence of the QAH effect with a Chern number (C) of 1 in the heterostructure.
• A previously unstudied, rich phase diagram was revealed by the effective Hamiltonian.

Conclusions:

• The graphene/MBT heterostructure provides a viable platform for realizing the QAH effect in monolayer graphene.
• This work offers a practical approach to exploring QAH and magnetic topological phases using the versatile MBT material family.