Shockley state in epitaxial Ag films on Au(1 1 1)

Epitaxial Ag ultra-thin films grown on Au(1 1 1) have been studied by scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES). In the submonolayer range, the spectroscopic measurements reveal the existence of two parabolic dispersive surface Shockley bands associated with the Au substrate and the Ag islands, respectively. The surface state in the Ag region is shifted by about 160 meV towards the Fermi level. High resolution measurements on Au(1 1 1) reveal the splitting of each band in two spin–orbit contributions. A reduction of this spin–orbit splitting is observed for a 1 ML Ag film. Moreover, an annealing of the interface leads to an interdiffusion and to an additional shift of the surface state.