Enhanced Intrinsic Spin Hall Effect of Bi Atoms on Ag(001) Surface

Spin Hall effect (SHE) of Bi atoms and impuritis on Ag(001) surface is investigated with density functional theory (DFT) calculations. A free standing Ag(001) layer has neglectable Spin Hall conductivity (SHC). However, we find that the addition of a small amount Bi atoms, either through adsorption of doping on the Ag(001) surface, the SHC may suddenly increase to larger than 2000/Ω.cm. Continous increase of Bi coververage after 1/9 monolayer causes gradual decrease of SHC, which becomes a constant value for Bi > 1 ML. Analysis of band structures and Berry curvatures indicate that the large SHC mainly results from the hybridzation of Ag s bands and Bi p bands. Further more, we find significant Rashba splitting in bands for Bi > 1 ML, which also contributes to the SHC.