Large Exchange Bias Effect and Coverage-Dependent Interfacial Coupling in CrI 3 /MnBi 2 Te 4 van der Waals Heterostructures

• Published in: Nano letters Vol. 23; no. 3; pp. 765 - 771
• Main Authors: Ying, Zhe, Chen, Bo, Li, Chunfeng, Wei, Boyuan, Dai, Zheng, Guo, Fengyi, Pan, Danfeng, Zhang, Haijun, Wu, Di, Wang, Xuefeng, Zhang, Shuai, Fei, Fucong, Song, Fengqi
• Format: Journal Article
• Language: English
• Published: United States 08.02.2023
• Subjects: exchange bias effect; magnetic topological insulators; coverage-dependent; interface coupling
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.2c02882

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 CrI /MnBi Te 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 CrI , 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 CrI and MnBi Te , pointing to coverage-dependent interfacial magnetic interactions. Our work will facilitate the development of topological and antiferromagnetic devices.