Tuning the Exchange Bias Effect in 2D van der Waals Ferro-/Antiferromagnetic Fe3GeTe2/CrOCl Heterostructures

The exchange bias effect is extremely expected in 2D van der Waals (vdW) ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures due to the high-quality interface. CrOCl possesses strong magnetic anisotropy at 2D limit, and is an ideal antiferromagnet for constructing FM/AFM heterostructures to explore the exchange bias effect. Here, the exchange bias effect in Fe3GeTe2 (FGT)/CrOCl heterostructures through both anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements is studied. In the AHE measurements, the exchange bias field (H-EB) at 3 K exhibits a distinct increase from approximate to 150 Oe to approximate to 450 Oe after air exposure, and such variation is attributed to the formation of an oxidized layer in FGT by analyzing the cross-sectional microstructure. The H-EB is successfully tuned by changing the FGT/CrOCl thickness and the cooling field. Furthermore, a larger H-EB of approximate to 750 Oe at 1.7 K in FGT/CrOCl heterostructure through RMCD measurements is observed, and it is proposed that the larger H-EB in RMCD measurements is related to the distribution of uncompensated spins at the interface. This work reveals several intriguing phenomena of the exchange bias effect in 2D vdW magnetic systems, which paves the way for the study of related spintronic devices.

Automated summary

In this study, the exchange bias effect in Fe3GeTe2 (FGT)/CrOCl heterostructures is investigated through anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements. The exchange bias field (H-EB) is successfully tuned by changing the FGT/CrOCl thickness and the cooling field. A larger H-EB in RMCD measurements is observed, which is proposed to be related to the distribution of uncompensated spins at the interface.