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1	Investigation of the magnetic and electronic structure of Fe in molecules and chalcogenide systems Taubitz, Christian 09 June 2010 (has links) In this work the electronic and magnetic structure of the crystals Sr2FeMoO6, Fe0.5Cu0.5Cr2S4, LuFe2O4 and the molecules FeStar, Mo72Fe30, W72Fe30 are investigated by means of X-ray spectroscopic techniques. These advanced materials exhibit very interesting properties like magnetoresistance or multiferroic behaviour. In case of the molecules they also could be used as spin model systems. A long standing issue concerning the investigation of these materials are contradicting results found for the magnetic and electronic state of the iron (Fe) ions present in these compounds. Therefore this work focuses on the Fe state of these materials in order to elucidate reasons for these problems. Thereby the experimental results are compared to multiplet simulations. Fe valence state Advanced materials XPS, XAS, XMCD Magnetoresistance 33.61 - Festkörperphysik 33.30 - Atomphysik, Molekülphysik 71.70.Ch - Crystal and ligand fields 75.47.Gk - Colossal magnetoresistance ddc:530