Polarity-Reversal of Exchange Bias in van der Waals FePS3/Fe3GaTe2 Heterostructures.

Abstract

Exchange bias (EB) in antiferromagnetic (AFM)/ferromagnetic heterostructures is crucial for the advancement of spintronic devices and has attracted significant attention. The common EB effect in van der Waals heterostructures features a low blocking temperature (Tb) and a single polarity. In this work, a significant EB effect with a Tb up to 150K is observed in FePS3/Fe3GaTe2 heterostructures, and in particular, the EB exhibits an unusual temperature-dependent polarity-reversal behavior. Under a high positive field-cooling condition (e.g., μ0H ≥0.5T), a negative EB field (HEB) is observed at low temperatures, and with increasing temperature, the HEB crosses zero at ≈20K, subsequently becomes positive and later approaches zero again at Tb. A model composed of a top FePS3/interfacial FePS3/Fe3GaTe2 sandwich structure is proposed. The charge transfer from Fe3GaTe2 to FePS3 at the interface induces net magnetic moments (∆M) in FePS3. The interface favors AFM coupling, and thus the reversal of ∆M of the interfacial FePS3 leads to the polarity-reversal of EB. Moreover, the EB can be extended to the bare Fe3GaTe2 region of the Fe3GaTe2 flake partially covered by FePS3. This work provides opportunities for a deeper understanding of the EB effect and opens a new route toward constructing novel spintronic devices.