Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.44: Poster

Mittwoch, 28. März 2012, 18:15–21:45, Poster B

STM investigation of ultra thin silver films on Nb(110) — •Matthias Stocker, Holger Pfeifer, Berndt Koslowski, and Paul Ziemann — Institut für Festkörperphysik, Universität Ulm, D-89081 Ulm

Thin silver films (in the monolayer range) were thermally evaporated onto Nb(110) at approximately 100 °C and analyzed by scanning tunneling microscopy (STM) and spectroscopy (STS) at 5.3 K. The Ag/Nb(110) forms islands of 2ML height which coalesce to form a contiguous layer at a nominal coverage of 2ML. On the islands we find quasi-periodic depressions of depth ~0.1 nm and period ~2 nm pointing to a significant stress within the Ag layer. Spectroscopy reveals a marked difference between the DOS off and on the island with strong resonances at (-1.4, -1.0, 0.0, 0.7) eV which cannot be attributed to quantum well states in the silver. The origin could be hybridization of Ag with Nb states at the interface. On the island, the DOS is strongly reduced above the Fermi energy indicating the development of the L gap in the Ag layer. The stress in the Ag layer with the locally varying strain leads to prominent changes in the DOS as revealed by dI/dV maps.