Large Exchange Bias Effect and Coverage-Dependent Interfacial Coupling in CrI3/MnBi2Te4 van der Waals Heterostructures

TL;DR

This study demonstrates a large, coverage-dependent exchange bias effect in CrI3/MnBi2Te4 heterostructures, revealing tunable interfacial magnetic coupling crucial for topological and antiferromagnetic device development.

Contribution

It reports the observation of a large, tunable exchange bias effect in CrI3/MnBi2Te4 heterostructures, highlighting coverage-dependent interfacial magnetic interactions.

Findings

Negative exchange bias decays with temperature

Positive exchange bias exceeds 300 mT in half-covered devices

Interfacial magnetic coupling is sensitive to coverage

Abstract

Igniting interface magnetic ordering of magnetic topological insulators by building a van der Waals heterostructure can help to reveal novel quantum states and design functional devices. Here, we observe an interesting exchange bias effect, indicating successful interfacial magnetic coupling, in CrI3/MnBi2Te4 ferromagnetic insulator/antiferromagnetic topological insulator (FMI/AFM-TI) heterostructure devices. The devices originally exhibit a negative exchange bias field, which decays with increasing temperature and is unaffected by the back-gate voltage. When we change the device configuration to be half-covered by CrI3, the exchange bias becomes positive with a very large exchange bias field exceeding 300 mT. Such sensitive manipulation is explained by the competition between the FM and AFM coupling at the interface of CrI3 and MnBi2Te4, pointing to coverage-dependent interfacial magnetic interactions. Our work will facilitate the development of topological and antiferromagnetic devices.