Electrical detection of magnetization of a layered semiconducting ferromagnet using WTe₂

Spin-orbit torque (SOT) switching devices fabricated by combining van der Waals (vdW) based semiconducting ferromagnets (FMs) and Weyl semimetal (WSMs) are appealing because of electric field-controlled magnetism and unconventional charge to spin conversion, which can be exploited for modular memory and logic devices. For instance, the vdW based FM semiconductors, such as Cr₂Ge₂Te₆ (CGT), offer us the opportunity to study SOT devices where electric field-controlled magnetism can be used for enhanced device functionalities¹. Also, we have recently shown that field-free deterministic switching of perpendicular magnet can be obtained by utilizing the unconventional spin orbit torque in WTe₂². In SOT devices, the electrical readout of the semiconducting FM layer is essential for device functionality. Electrical detection of magnetization in conventional insulating/ semiconducting ferromagnet (FM) is routinely achieved by utilizing spin hall effect generated by the adjacent heavy metal layer³. The electrical readout of magnetization in 2D semiconducting FM has been demonstrated by coupling Cr₂Ge₂Te₆ with heavy metals⁴ and topological insulators⁵. However, few reports have shown electrical detection in a vdW based semimetal/FM-semiconductor heterostructures. Our initial results have demonstrated observation of spin Hall-induced anomalous Hall resistance and spin magnetoresistance in WTe₂/CGT bilayers. On the same device, the resistance of individual CGT is more than 100 times higher than the resistance of the bilayer structure, therefore most of the current is flowing through WTe₂ layer. We will present detailed measurements, which are required to understand the the interplay between the electric gating and observed spin magnetoresistance at the interface in WTe₂/CGT bilayer systems.

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