Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Nanostructures at Surfaces: 1D and 2D Structures
O 73.6: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Structural and electronic properties of the triangular lattice of Sn on SiC(0001) — •Florian Adler1, Stefan Glaß1, Gang Li2, Julian Aulbach1, Philipp Höpfner1, Werner Hanke2, Jörg Schäfer1, and Ralph Claessen1 — 1Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Germany — 2Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany
Here we report on a novel two-dimensional electron system on a triangular lattice, namely the √3 × √3 reconstruction of Sn on SiC(0001). Using a newly developed recipe of gas phase hydrogen etching, well ordered SiC surfaces could be prepared. By evaporation of Sn and subsequent annealing, a triangular lattice of Sn on SiC(0001) with a coverage of 1/3 monolayer was realized. Both the substrate preparation and the evaporation process were monitored by low-energy electron diffraction and high-resolution scanning tunneling microscopy. While simple electron counting results in a half-filled valence band and therefore metallic behavior, first angle-resolved photoemission data shows a broad, weakly dispersing band with no spectral weight at the Fermi level, indicating Mott-Hubbard physics. The system is isostructural to the well explored Mott-insulator √3 × √3 Sn on Si(111), but with a 20% smaller lattice constant. Due to the increased hopping one might expect to be closer to the insulator-metal boundary of the Hubbard model. However, the large bandgap of the substrate may also change the effective Hubbard-U due to a different substrate-related screening. Similarities and differences between both systems will be discussed.