Research on Spin-Valve Effect Based on Fe3GaTe2/WSe2/Fe3GaTe2 van der Waals Heterostructures

Abstract

Spin valves are core components in spintronics, widely used in magnetic memory and sensing. To advance the miniaturization and low power consumption of 2D spintronic devices, this study systematically investigates the magnetotransport properties of a fully 2D van der Waals spin valve heterostructure based on ferromagnetic Fe₃GaTe₂ and semiconductor WSe₂. Fe₃GaTe₂ single crystals were synthesized via a high-temperature self-flux technique, and their excellent crystalline quality and uniform elemental distribution were confirmed by Raman spectroscopy, XRD, XPS, and EDS. Subsequently, the Fe₃GaTe₂/WSe₂/Fe₃GaTe₂ vertical heterostructure was fabricated using mechanical exfoliation and dry transfer techniques, and its transport properties were evaluated in a physical property measurement system. Experimental results demonstrate that the heterojunction shows a strictly linear I-V response at 250 K, establishing an excellent Ohmic contact. Under an out-of-plane magnetic field, the device exhibits a distinct step-like magnetoresistance curve at 250 K, firmly confirming the spin valve effect. Furthermore, the magnetoresistance ratio decays significantly as the bias current increases from 1 nA to 1 μA, and remains highly constant over a 360° range when the direction of the applied magnetic field is varied at 250 K, demonstrating a completely angular-independent characteristic. This unique isotropic transport behavior originates from the intrinsic strong perpendicular magnetic anisotropy of Fe₃GaTe₂. This study verifies the feasibility of achieving spin valve modulation in all 2D systems and provides a solid physical basis for constructing magnetic angular-insensitive spin transport devices.