/Heavy Metal Heterostructures*

Among the most promising candidates for practical spintronic designs are current-controlled magnetic devices such as spin-transfer torque (STT) and spin-orbit torque (SOT) devices. One major challenge however is the low power switching of the ferromagnetic (FM) layer, with van der Waals (vdW) ferromagnetic materials such as Fe₃GeTe₂ (FGT) representing a promising avenue to mitigate this issue. Materials in this new class offer a multitude of novel properties such as large anomalous Hall angles and spin polarizations that make them desirable for device applications. While some previous work has successfully demonstrated efficient SOT driven switching in FGT/platinum heterostructures, emergent magnetic properties of these structures have yet to be probed in depth. Here, we investigated FGT/heavy metal (HM) heterostructures using the anomalous Hall effect (AHE). We show that structures prepared using transfer can exhibit new behavior which we attribute to magnetic proximity effects at the FM/HM interface. New features include enhanced coercive fields and tails in measured hysteresis loops compared to devices that contain only FGT. These results differ notably from devices presented elsewhere in which the heavy metal was sputtered directly onto FGT. These results indicate that the quality of the FM/HM interface has significant impact on the properties of the vdW magnets and the SOT devices.