Spin-orbit splitting of the Shockley state in the Ag/Au(111) interface

We have studied the modification of Au(111) surface state parameters with Ag deposition. We unambiguously evidence a continuous decrease in the spin-orbit splitting of the two surface state subbands upon increasing Ag coverage. An annealing leads to the formation of a chemically disordered Ag-Au alloy. This alloy formation is accompanied by an increase in the spin-orbit splitting. We established a quantitative correlation between the amplitude of this splitting and the relative amount of Au and Ag atoms probed by the surface state wave function proving the atomic character of the spin-orbit splitting. Control of the Ag-Au interface allows a continuous fine tuning of surface state properties; in particular, the k-dependent spin polarization.