Observation of Interfacial Antiferromagnetic Coupling between Magnetic Topological Insulator and Antiferromagnetic Insulator

TL;DR

This study demonstrates interfacial antiferromagnetic coupling between a magnetic topological insulator and an antiferromagnetic insulator, revealing new ways to manipulate magnetic and topological properties for spintronic applications.

Contribution

It reports the first observation of interfacial AFM coupling in magnetic TI/AFM heterostructures and shows how this coupling influences magnetic and topological properties.

Findings

Interfacial AFM coupling favors magnetic alignment between TI and Cr2O3.

Field cooling induces a crossover from negative to positive exchange bias.

Interfacial exchange enhances the Curie temperature of the magnetic TI.

Abstract

Inducing magnetic orders in a topological insulator (TI) to break its time reversal symmetry has been predicted to reveal many exotic topological quantum phenomena. The manipulation of magnetic orders in a TI layer can play a key role in harnessing these quantum phenomena towards technological applications. Here we fabricated a thin magnetic TI film on an antiferromagnetic (AFM) insulator Cr2O3 layer and found that the magnetic moments of the magnetic TI layer and the surface spins of the Cr2O3 layers favor interfacial AFM coupling. Field cooling studies show a crossover from negative to positive exchange bias clarifying the competition between the interfacial AFM coupling energy and the Zeeman energy in the AFM insulator layer. The interfacial exchange coupling also enhances the Curie temperature of the magnetic TI layer. The unique interfacial AFM alignment in magnetic TI on AFM insulator heterostructures opens a new route toward manipulating the interplay between topological states and magnetic orders in spin-engineered heterostructures, facilitating the exploration of proof-of-concept TI-based spintronic and electronic devices with multi-functionality and low power consumption.