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TT: Fachverband Tiefe Temperaturen

TT 76: Poster Session: Transport 2

TT 76.15: Poster

Donnerstag, 23. März 2017, 15:00–19:00, P2-OG1

Surface transport on thin semi-metallic films: The role of thickness and magnetic impurities — •Philipp Kröger, Marianna Siemens, Herbert Pfnür, and Christoph Tegenkamp — Leibniz Universität Hannover, Institut für Festkörperphysik, Appelstr. 2, 30167 Hannover

Bismuth has attracted a lot of interest because of its unique electronic properties such as low carrier concentrations and high carrier mobilities. Thereby, epitaxial growth of high-quality thin films opens new pathways to tailor the electronic properties further, e.g. by quantum confinement and alloy formation, giving rise to topologically non-trivial states in this material class. In this study we concentrate on Bi films grown on Si(111). Thin Bi(111) films become semiconducting due to the quantum-size-effect. Thus the peculiar spin texture of the surface states, induced by the Rashba effect, were studied directly by temperature and magnetic field dependent transport. Only at low temperatures (T<50 K) the conductance G turned out to be governed by surface states while at higher temperatures activated transport from bulk channels sets it. We have carefully analyzed the G(T)-behavior as a funnction of film thickness. With decreasing film thickness, the bulk gap increases, as expected due to the quantum size effect. However for thinner films the gap decreases. The reason is an interface-interface interaction which renormalizes strongly the Fermi surface.