Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.47: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Unoccupied electronic structure of TiOCl studied by XAS — •Sebastian Glawion1, Götz Berner1, Matthias Schlachter1, Michael Sing1, Markus Hoinkis2, Gianina Gavrila3, Leonardo Pisani4, Roser Valenti4, and Ralph Claessen1 — 1Experimentelle Physik 4 and Röntgen Research Center for Complex Materials, Universität Würzburg, D-97074 Würzburg, Germany — 2Experimentalphysik II, Universität Augsburg, D-86135 Augsburg, Germany — 3Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz, Germany — 4Institut für Theoretische Physik, Universität Frankfurt, D-60054 Frankfurt, Germany
TiOCl is a Mott-insulating quantum magnet showing a dimerized spin-Peierls phase for temperatures below T_c1=67K. This phase is reached through two distinct phase transitions. The intermediate phase shows incommensurate order, while the susceptibility of the high-T phase nicely reflects the behaviour of a 1D Heisenberg antiferromagnet. Intensive studies in this latter phase have been conducted on the occupied density of states in the valence band both by (AR)PES and various calculations. However, since the low-T phase cannot be reached by PES due to charging problems, we conducted X-ray absorption studies searching for possible changes in the electronic structure induced by the different kinds of ordering. Our results nicely agree with previous LDA+U and GGA+U calculations but do not seem to show major differences between the different phases.