Twist angle controlled collinear Edelstein effect in van der Waals heterostructures

Abstract

The generation of spatially homogeneous spin polarization by application of electric current is a fundamental manifestation of symmetry-breaking spin--orbit coupling (SOC) in solid-state systems, which underpins a wide range of spintronic applications. Here, we show theoretically that twisted van der Waals heterostructures with proximity-induced SOC are candidates par excellence to realize exotic spin-charge transport phenomena due to their highly tunable momentum-space spin textures. Specifically, we predict that graphene/group-VI dichalcogenide bilayers support room temperature spin--current responses that can be manipulated via twist-angle control. For critical twist angles, the non-equilibrium spin density is pinned parallel to the applied current. This effect is robust against twist-angle disorder, with graphene/$\text{WSe}_{2}$ possessing a critical angle (purely collinear response) of $\theta_{c} \simeq 14^{\circ}$. A simple electrical detection scheme to isolate the collinear Edelstein effect is proposed.