Two-domains bulklike Fermi surface of Ag films deposited ontoSi(111)−(7×7)

Abstract

Thick metallic silver films have been deposited onto $\mathrm{Si}(111)\ensuremath{-}(7\ifmmode\times\else\texttimes\fi{}7)$ substrates at room temperature. Their electronic properties have been studied by using angle-resolved photoelectron spectroscopy (ARPES). In addition to the electronic band dispersion along the high-symmetry directions, the Fermi surface topology of the grown films has been investigated. Using ARPES, the spectral weight distribution at the Fermi level throughout large portions of the reciprocal space has been determined at particular perpendicular electron-momentum values. Systematically, the contours of the Fermi surface of these films reflected a sixfold symmetry instead of the threefold symmetry of the Ag single crystal. This symmetry loss has been attributed to the fact that these films appear to be composed by two sets of domains rotated $60\ifmmode^\circ\else\textdegree\fi{}$ from each other. Extra photoemission features at the Fermi level were also detected, which have been attributed to the presence of surface states and $\mathrm{sp}$-quantum states. The dimensionality of the Fermi surface of these films has been analyzed, studying the dependence of the Fermi surface contours with the incident photon energy. The behavior of these contours measured at particular points along the Ag $\ensuremath{\Gamma}L$ high-symmetry direction puts forward the three-dimensional character of the electronic structure of the investigated films.