Magnetic proximity effect at the 3D topological insulator/magnetic insulator interface

TL;DR

This study uses density functional theory to analyze the magnetic proximity effect at the Bi2Se3/MnSe(111) interface, revealing how topological and ordinary states interact and open a gap in the Dirac cone, crucial for quantum device applications.

Contribution

It provides a detailed theoretical analysis of the magnetic proximity effect at the TI/MI interface, highlighting the origin of the Dirac cone gap and the behavior of interfacial states.

Findings

Gapped ordinary bound state appears at the interface.

Topological Dirac state relocates to deeper layers.

Gap in Dirac cone results from overlapping states.

Abstract

The magnetic proximity effect is a fundamental feature of heterostructures composed of layers of topological insulators and magnetic materials since it underlies many potential applications in devices with novel quantum functionality. Within density functional theory we study magnetic proximity effect at the 3D topological insulator/magnetic insulator (TI/MI) interface in Bi$_2$Se$_3$/MnSe(111) system as an example. We demonstrate that a gapped ordinary bound state which spectrum depends on the interface potential arises in the immediate region of the interface. The gapped topological Dirac state also arises in the system owing to relocation to deeper atomic layers of topological insulator. The gap in the Dirac cone is originated from an overlapping of the topological and ordinary interfacial states. This result being also corroborated by the analytic model, is a key aspect of the magnetic proximity effect mechanism in the TI/MI structures.