Spin-polarized photocurrents in bilayer VS 2 : photogalvanic effect with magnetic and polarization light control

Abstract The photogalvanic effect (PGE) plays a crucial role in spintronic applications. However, the coexistence and controllable generation of pure spin current (PSC) and fully spin-polarized current (FSPC) within a single material system remain largely unexplored. In this work, we investigate the PGE in bilayer VS₂ using quantum transport simulations based on the Keldysh nonequilibrium Green’s-function formalisms combined with density-functional theory. Bilayer VS₂ with 2 H - and 3 R -type stackings lacks spatial inversion symmetry and exhibits appreciable photocurrents under linearly polarized light. These photocurrents exhibit a cosine dependence on polarization angles, consistent with the phenomenological theory of PGE. The photocurrent in the antiparallel configuration (APC) is significantly enhanced compared with that in the parallel configuration (PC), revealing a prominent spin-valve effect. Notably, FSPC is realized in the PC, whereas PSC is generated in the APC, and both can be effectively controlled by tuning photon energy and polarization angle. Interestingly, the magnetoresistance ratio exceeds 90% for most photon energies, reaching as high as 100%, and the perfect spin polarization efficiency achieves 100% in the PC and 8 × 10 3 in the APC. These findings highlight bilayer VS₂ as a promising candidate for high-performance spintronic devices.