Proximity Induced Spin Currents and Spin-orbit Torques in Graphene on 1T-TaS2

We investigate the charge-to-spin conversion in graphene on 1T-TaS2 using an effective tight-binding model and quantum transport calculations, with a focus on the role of the Rashba phase angle. We discuss also limiting cases where for the zero Rashba phase angle a spin accumulation is observed for injected electrons with spins perpendicular to the transport direction, which is indicative of the Rashba-Edelstein effect. Conversely, for injected electrons with spins parallel to the transport direction, the dominant mechanism is the spin Hall effect. Interestingly, at the Rashba phase angle of 90 degrees, we observe a switching of the charge-to-spin mechanism between the two quantization axis directions, resulting in a nonequilibrium spin density that is pinned parallel to the applied current. For any phase angle between these two limits, a spin Hall effect is observed for both quantization axis directions. For the charge density wave ferromagnetic phase of the 1T-TaS 2 , we calculated spin-orbit torque acting on proximity-induced magnetization in graphene. We found an angle phase shift of the angular torque dependence and relate it to the proximity-induced exotic spin textures due to the Rashba phase angle. Our findings confirm the relationship between the Rashba phase angle and charge-to-spin conversion in graphene on 1T-TaS 2 monolayer which may have important implications for the design of graphene-based spintronic devices.