Large Negative Magnetoresistance in All‐2D‐Materials‐Based Spin Valves

Abstract

Two‐dimensional (2D) magnetic materials have attracted enormous interest and opened up a new direction to novel spintronic applications. Herein, a large negative magnetoresistance (MR) in all‐2D‐materials‐based vertical magnetic spin valves with nano/micro bubbles existing at the interface between the spacer layer (MoS2) and the top ferromagnetic electrode layer (Cr0.85Te or Fe3GeTe2) is demonstrated. The large negative MR, with a magnitude of ≈21.5% attained in Cr0.85Te/MoS2/Fe3GeTe2, could be fully suppressed by the elimination of the bubbles after a short argon‐protected annealing, indicating the determining role of the bubbles in modulating the spin‐related transport behavior. First‐principles calculations based on density function theory (DFT) illustrate that the compressive strain can significantly modify the spin‐resolved electronic band structures of the 2D ferromagnetic materials, and hence alter the spin polarization near the Fermi level, accounting for the negative MR phenomena with the conventional two‐current model. Herein, a new route to all‐2D‐materials‐based spintronic devices via strain engineering is provided, and also offers a new insight into the role of bubbles formed during fabricating 2D heterostructures in developing exotic properties and novel functionalities.