Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 6: Electronic structure I
O 6.2: Vortrag
Montag, 23. März 2009, 11:30–11:45, SCH A216
The Two-Dimensional Electron System Au/Ge(111) Studied by Angle-Resolved Photoemission — •Philipp Höpfner1, Maik Heßmann1, Jörg Schäfer1, Carsten Enderlein2, Thomas Braun2, Christian Blumenstein1, Sebastian Meyer1, Karsten Horn2, and Ralph Claessen1 — 1Physikal. Institut, Universität Würzburg, 97074 Würzburg — 2Fritz-Haber-Institut, 14195 Berlin
Two-dimensional electron systems (2DES) at surfaces offer high potential for studying correlation effects. Adsorbed metals on (111) semiconductor substrates provide intriguing realizations of a 2DES by forming (√3 × √3) reconstructions with metal coverage (Sn, Pb, Au etc.) not exceeding one monolayer. Electron-electron interaction is assumed to play an important role. Examples include Sn/Ge(111) as a rather highly correlated system which even exhibits a Mott-Hubbard transition. In particular, the choice of metal species and substrate will affect orbital character and overlap. By this means, it should be possible to tailor the correlation strength, and to thus understand the mechanisms behind it. Here we explore the little studied noble metal adsorbates by addressing the Au/Ge(111)-(√3 × √3) system. Angle-resolved photoelectron spectroscopy (ARPES) reveals a metallic character, and for the first time provides an account of the Fermi surface topology. In addition, ARPES determination of the band dispersion reveals electron- and hole-like bands. Their behavior and the effective masses are suggestive of a less correlated electron system, thereby reflecting the tunability of the electronic interactions in a monolayer 2DES.