Anomalous thickness dependence of the Hall effect in ultrathin Pb layers on Si(111)

The magnetoconductive properties of ultrathin Pb films deposited on Si(111) are measured and compared with density-functional electronic band-structure calculations on two-dimensional, free-standing, 1 to 8 monolayers thick Pb(111) slabs. A description with free-standing slabs is possible because it turned out that the Hall coefficient is independent of the substrate and of the crystalline order in the film. We show that the oscillations in sign of the Hall coefficient observed as a function of film thickness can be explained directly from the thickness dependent variations of the electronic bandstructure at the Fermi energy.Comment: 4 pages incl. 3 figures, RevTeX, to appear in Phys. Rev.

Conductivity of ultrathin Pb films during growth on Si(111) at low temperatures

The electronic properties of thin metallic films strongly depend on their structure. For the preparation of ultrathin films (0.8 to 12 ML) Pb was grown on a Si (111)-$7\times 7$ structure at temperatures below 25 K. Percolation as measured by DC conductance starts at 0.7 ML. Up to 4 ML the growing film is disordered. During continuation of the growth the film recrystallizes epitaxially and layer-by-layer growth connected with oscillations of conductivity and LEED intensities is observed even at 25 K. The defect structure as determined by SPA-LEED and the quantum size effect allow a quantitative description of the conductivity oscillations. The experiments show, that the electronic properties of ultrathin Pb films are clearly correlated with the structural properties of the film

Electronic structure and excitations on clean and nanostructured metal surfaces

11 páginas, 11 figuras.We present a brief overview of recent studies and new theoretical results for electron-phonon interaction in the [`(Y)]Y surface states on FCC(110) noble metal surfaces as well as in surface and quantum-well states of thin films. We discuss the oscillations of electron-phonon coupling parameter λ and the respective contribution to the lifetime broadening of these states. We analyse the effect of spin-orbit splitting of surface states on an electron-electron contribution to lifetimes of excited electrons (holes). Oscillations of the electron-electron contribution and quadratic dependence of the linewidth on energy is discussed for ultrathin Pb(111) films.We gratefully acknowledge partial support by the Department of Education of the Basque Country Governement, the University of the Basque Country (project GV-UPV/EHU, grant IT-366-07), and Ministerio de Ciencia y Tecnología (grant FIS2007-66711-C02-01).Peer reviewe