Spin-resolved photoemission by circularly polarized light from Au on Ag(111): experiment and theory

The electronic structure of 1 ML and 2 ML Au on Ag(111) has been studied experimentally and theoretically by spin-, angle- and energy-resolved photoemission in the highly symmetrical set-up of normally incident circularly polarized VUV radiation and normal electron emission. The measured spectra agree rather well with their relativistically calculated counterparts and can be consistently interpreted with the aid of spin- and layer-resolved densities of states. The spin polarization of spectral peaks directly reflects the double group symmetry type of the the corresponding initial states. For 1 ML (2 ML) Au on Ag(111) there are two (four) Au-derived states, which are confined to the adlayers (“film states”). For 2 ML Au, the “film-state” photoemission intensity depends strongly on the photon energy, which is understood as an interference effect. Since the agreement with the experimental photoemission spectra is improved by calculations assuming an additional Ag layer on top, and since the Au-derived experimental features are substantially broadened, an intermixing of Au and Ag is very likely.