Electronic structure study of ultrathin Ag(111) films modified by a Si(111) substrate and √3 x √3-Ag2Bi surface

Angle-resolved photoemission spectroscopy experiments show that the electronic structure of a Ag(111) film grown on Si(111) is markedly perturbed by the formation of a root 3 x root 3-Ag2Bi Rashba-type surface alloy. Four spin-split surface states, with different band dispersions and energy contours, intercept and hybridize selectively with the sp-derived quantum well states of the Ag layer. Detailed two-dimensional band mapping of the system was carried out and constant energy contours at different energies result in hexagonal-, star-and flower-like distortions of the quantum well states as a result of various interactions. Further wavy-like modulations of the electronic structure of the film are found to originate from umklapp reflections of the Ag film states according to the surface periodicity.