Exchange Bias Effect in Ferro-/Antiferromagnetic van der Waals Heterostructures

• Published in: Nano letters Vol. 20; no. 5; pp. 3978 - 3985
• Main Authors: Srivastava, Pawan Kumar, Hassan, Yasir, Ahn, Hyobin, Kang, Byunggil, Jung, Soon-Gil, Gebredingle, Yisehak, Joe, Minwoong, Abbas, Muhammad Sabbtain, Park, Tuson, Park, Je-Geun, Lee, Kyung-Jin, Lee, Changgu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.05.2020
• Subjects: FM/AFM heterostructures; magnetic ordering; exchange bias effect; magnetic anisotropy; van der Waals magnets; electric field effect
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.0c01176

The recent discovery of magnetic van der Waals (vdW) materials provides a platform to answer fundamental questions on the two-dimensional (2D) limit of magnetic phenomena and applications. An important question in magnetism is the ultimate limit of the antiferromagnetic layer thickness in ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures to observe the exchange bias (EB) effect, of which origin has been subject to a long-standing debate. Here, we report that the EB effect is maintained down to the atomic bilayer of AFM in the FM (Fe3GeTe2)/AFM (CrPS4) vdW heterostructure, but it vanishes at the single-layer limit. Given that CrPS4 is of A-type AFM and, thus, the bilayer is the smallest unit to form an AFM, this result clearly demonstrates the 2D limit of EB; only one unit of AFM ordering is sufficient for a finite EB effect. Moreover, the semiconducting property of AFM CrPS4 allows us to electrically control the exchange bias, providing an energy-efficient knob for spintronic devices.