Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.37: Poster
Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F
Insulating Ground State of Sn/Si(111)-(√(3)×√(3))R30∘ — •Silvio Modesti1,2,3, Luca Petaccia1,4, Gustavo Ceballos1,5, Ivana Vobornik1, Giancarlo Panaccione1, Giorgio Rossi1, Luca Ottaviano6, Silvano Lizzit4, and Andrea Goldoni4 — 1Laboratorio Nazionale TASC-INFM, S.S. 14 Km 163.5, 34012 Trieste, Italy — 2Dipartimento di Fisica, Universita’ di Trieste, v. Valerio 2 I-34127, Trieste, Italy — 3Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, D-20355 Hamburg — 4Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste, Italy — 5ICN, UAB Campus, E-08193 Bellaterra (Barcelona), Spain — 6Universita’ dell’Aquila, via Vetoio 10, 67010 Coppito-L’Aquila, Italy
The Sn/Si(111)-(√(3)×√(3))R30∘ surface, having an odd number of electrons per surface unit cell, was so far believed to be metallic according to the electron counting argument. One third of a monolayer of tin adatoms in the T4 site forms a narrow surface state band that is half filled, and therefore prone to structural and electronic instabilities. We show, by using tunneling spectroscopy, scanning tunneling microscopy, photoemission, and photoelectron diffraction, that below 70 K this surface has a very low density of states at the Fermi level and is not appreciably distorted [1]. The experimental results are compatible with the magnetic insulating Mott-Hubbard ground state predicted by LSDA + U calculations [2]
[1] S. Modesti, et al., Phys. Rev. Lett. 98, 126401 (2007) [2] G. Profeta and E. Tosatti, Phys. Rev. Lett. 98, 086401 (2007).