Temperature-robust exchange bias and spin-orbit torque switching in van der Waals heterostructure

Exchange bias (EB) in ferromagnetic/antiferromagnetic materials is a novel idea for high-density spintronic devices. Van der Waals (vdW) heterostructures offer a promising solution, enabling a “Lego” like assembly without interface or adding dopants, opposite to traditional heterostructures. However, in typical vdW heterostructures, the EB effect exists at low temperatures and only one polarity. This work addresses these challenges by using Fe₃GaTe₂/NiPS₃ heterostructures whose EB can survive at higher temperatures and polarities flip. The exchange bias (EB) of the device persists up to 150 K and can have its polarity reversed by altering the stacking direction during fabrication. Simultaneously, an anomalous Hall effect (AHE) with a coercive field of approximately 0.9 T is observed at 5 K and remains detectable up to 300 K. The device further shows the spin-orbit torque (SOT)-induced magnetization switching up to room temperature. Under low field-cooling conditions (e.g., ≥2 mT), we observe an EB field (H_EB) up to 1 mT, which reached 110 mT at 1.5 T. H_EB becomes zero above 150 K, showing a non-discernible EB effect, whereas the AHE persists up to room temperature. Similarly, in the Fe₃GaTe₂/NiPS₃ and NiPS₃/Fe₃GaTe₂, different stacking layers at the interface induce the net magnetic effect and flip the magnetization direction due to magnetic domains at the Fe₃GaTe₂ layer. The results show that strong interlayer coupling within these layers generates significant AHE and high H_EB with blocking temperatures up to 150 K, making it suitable for the new 2D spintronic device applications. (Figure presented.).