Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.7: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
Structural influence towards transport: Pb wires on Si(557) — •Marcin Czubanowski, Annemarie Schuster, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover, Deutschland
The adsorption of 1.3 ML of Pb on Si(557) substrates followed by annealing at 640K leads to the formation of an anisotropic metallic structures as revealed by conductivity, STM and ARPES measurements. Those structures below 78K show metallic conductance along the Pb-chains, whereas in the direction perpendicular to the chain-structure an insulating behavior has been found. Additionally, ARPES measurements have shown that below Tc, those structures undergo complete Fermi nesting in the direction normal to the structure. In our recent LEED experiments, the chain structure has been systematically investigated as a function of temperature by means of SPA-LEED analysis. The adsorption of Pb transforms (locally) the surface into a regularly stepped (223) facet below Tc. This structure undergoes reversibly a commensurable-incommensurable phase transition at Tc = 78K as judged from changes in position of step diffraction spots in the [11 2] direction and also the periodicity of domain wall reflexes in the [11 0] direction. Furthermore, the transition depends crucially on the Pb coverage. If the steps are decorated by excess Pb, e.g. 1.5ML, the transition is strongly suppressed.