Dresden 2014 – wissenschaftliches Programm
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SYOM: Symposium One-dimensional Metals: Reality or Fiction
SYOM 2: Posters: One-Dimensional Metals: Reality or Fiction (jointly organized by DS, HL, O, TT)
SYOM 2.21: Poster
Donnerstag, 3. April 2014, 16:00–19:00, P1
The conductance phase transition of Si(5 5 7)-Pb probed by Raman and reflectance anisotropy spectroscopy — •Arne Baumann1, Sandhya Chandola1, Jochen Räthel1, Eugen Speiser1, Daniel Lükermann2, Christoph Tegenkamp2, and Norbert Esser1 — 1Leibniz-Institut für Analytische Wissenschaften – ISAS – e. V., Albert-Einstein-Straße 9, 12489 Berlin, Germany — 2Leibniz Universität Hannover, Institut für Festkörperphysik, Appelstraße 2, 30167 Hannover, Germany
Si(5 5 7)-Pb is a model system for a quasi-1D conductor below a phase transition at 78 K, resulting in an anisotropic 2D-phase. The adsorption of 1.31 ML of Pb on the vicinal Si(5 5 7) surface induces a refacetting of the surface into evenly stepped (2 2 3) facets, decorated by wire-like Pb nanostructures. Reflectance anisotropy spectroscopy (RAS) is applied to probe surface band structure transitions and polarized Raman spectroscopy (RS) to characterize vibrational properties.
In RAS measurements the low and high temperature phases exhibit an anisotropic optical conductance behavior and optical transitions in the region between 0.7 and 1.7 eV. This can be assigned to the Pb induced reformation of the surface.
Temperature-dependent RS measurements show new Pb-induced surface phonon modes, while Si-adatom surface vibrational modes persist. A reformation of the terrace structure at 78 K can be excluded. A structural phase transition can only occur on the step edges or between the individual (2 2 3) facets.