  The exchange bias phenomenon, inherent in exchange-coupled ferromagnetic and
antiferromagnetic systems, has intrigued researchers for decades. Van der Waals
materials, with their layered structure, provide an optimal platform for
probing such physical phenomena. However, achieving a facile and effective
means to manipulate exchange bias in pristine van der Waals heterostructures
remains challenging. In this study, we investigate the origin of exchange bias
in MnPS3/Fe3GeTe2 van der Waals heterostructures. Our work demonstrates a
method to modulate unidirectional exchange anisotropy, achieving an
unprecedented nearly 1000% variation through simple thermal cycling. Despite
the compensated interfacial spin configuration of MnPS3, magneto-transport
measurements reveal a huge 170 mT exchange bias at 5 K, the largest observed in
pristine van der Waals antiferromagnet-ferromagnet interfaces. This substantial
magnitude of the exchange bias is linked to an anomalous weak ferromagnetic
ordering in MnPS3 below 40 K. On the other hand, the tunability of exchange
bias during thermal cycling is ascribed to the modified arrangement of
interfacial atoms and changes in the vdW gap during field cooling. Our findings
highlight a robust and easily adjustable exchange bias in van der Waals
antiferromagnetic/ferromagnetic heterostructures, presenting a straightforward
approach to enhance other interface related spintronic phenomena for practical
applications.
