Vertical WS2 spin valve with Ohmic property based on Fe3GeTe2 electrodes*

Abstract

The two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have been recently proposed as a promising class of materials for spintronic applications. Here, we report on the all-2D van der Waals (vdW) heterostructure spin valve device comprising of an exfoliated ultra-thin WS2 semiconductor acting as the spacer layer and two exfoliated ferromagnetic Fe3GeTe2 (FGT) metals acting as ferromagnetic electrodes. The metallic interface rather than Schottky barrier is formed despite the semiconducting nature of WS2, which could be originated from the strong interface hybridization. The spin valve effect persists up to the Curie temperature of FGT. Moreover, our metallic spin valve devices exhibit robust spin valve effect where the magnetoresistance magnitude does not vary with the applied bias in the measured range up to 50 μA due to the Ohmic property, which is a highly desirable feature for practical application that requires stable device performance. Our work reveals that WS2-based all-2D magnetic vdW heterostructure, facilitated by combining 2D magnets, is expected to be an attractive candidate for the TMDCs-based spintronic applications.