Charge-to-spin conversion in twisted graphene/WSe2 heterostructures

We investigate the twist-angle dependence of spin-orbit coupling proximity effects and charge-to-spin conversion (CSC) in graphene/WSe2 heterostructures from first principles. The CSC is shown to strongly depend on the twist angle, with standard Rashba-Edelstein and disorder-free spin Hall efficiencies optimized near 30∘ twisting. Symmetry breaking due to twisting also gives rise to an unconventional Rashba-Edelstein effect, with electrically generated nonequilibrium spin densities possessing spins collinear to the applied electric field. Our work provides a perspective on the electrical generation of spins in van der Waals heterostructures.