Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 27: Time-Resolved Spectroscopy II

O 27.2: Talk

Tuesday, February 26, 2008, 11:30–11:45, MA 043

Photoelectron microscopy of the Mott-Hubbard transition at inhomogeneously Rb adsorbed 1T-TaS₂ surfaces — •Dirk Rahn¹, Hans Starnberg², Martin Marczynski-Bühlow¹, Tim Riedel¹, Jens Buck¹, Kai Rossnagel¹, and Lutz Kipp¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Kiel, D-24098 Kiel, Germany — ²Department of Physics, Göteborg University and Chalmers University of Technology, SE-41296 Göteborg, Sweden

Layered 1T-TaS₂ is of particular interest because it shows a rich phase diagram including various charge-density-wave phases and a first-order metal-insulator transition at about 180K which is widely understood as a Mott-Hubbard-type localization. Using angle-resolved photoemission, it has been shown that a similar metal-insulator transition at the surface of 1T-TaS₂ can be induced already at room temperature by simple adsorption of Rb [1]. To further investigate this emerging transition we have tried to prepare sharp Rb domains at the surface of 1T-TaS₂. Photoelectron microscopy measurements at beamline BL 31 at MAX-lab (Lund) and photoelectron spectroscopy measurements at beamline BW 3 at HASYLAB (Hamburg) show that it is indeed possible to prepare such a sharp Rb domain and that the Mott-Hubbard transiton is taking place in the Rb adsorbed region. Photoelectron microscopy images of the inhomogeneously Rb adsorbed surface will be presented as well as photoelectron spectra at sites with different alkali metal concentrations. This work is supported by the DFG Forschergruppe FOR 353 and the European Community - Research Infrastructure Action. [1] Rossnagel et. al. Phys. Rev. Lett. 95, 126403 (2005).