Switchable exchange bias resulting from correlated domain structures in orthogonally coupled antiferromagnet/ferromagnet van der Waals heterostructures

Abstract

Van der Waals (vdW) magnetic heterostructures offer a versatile platform for engineering interfacial spin interactions with atomic precision, enabling nontrivial spin textures and dynamics behavior. In this work, robust asymmetric magnetization reversal and exchange bias are reported in Fe3GeTe2 (FGT), driven by interlayer exchange coupling with the A-type antiferromagnet CrSBr. Despite the orthogonal magnetic anisotropies–out-of-plane easy axis in FGT and in-plane in CrSBr–a strong interfacial exchange interaction that gives rise to pronounced and switchable exchange bias and asymmetric switching in FGT is observed, persisting up to the Néel temperature of CrSBr (∼132 K) as revealed by anomalous Hall effect measurements. The microscopic origin of this behavior is uncovered through cross-sectional magnetic imaging of the domain structure using off-axis electron holography. The results reveal that the asymmetric switching and exchange bias arise from the influence of CrSBr on the domain configuration of FGT, where the in-plane antiferromagnetic state of CrSBr promotes the formation of stripe-like domain structures in FGT with circular rotation of magnetization in the cross-sectional bc plane defined by the easy axes of both FGT and CrSBr. These findings elucidate the mechanism of exchange bias in orthogonally coupled vdW systems and demonstrate a pathway for stabilizing 3D domain structures in ferromagnets through interfacial exchange interactions.