Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.19: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Structural studies on transition metal oxides with only one or two electrons in the 3d shell — •A. C. Komarek1, T. Möller1, M. Isobe2, M. Gottschlich1, M. Meven3, M. Hölzel3,4, A. Senyshyn3,4, W. Morgenroth5, D. Trots5,4, M. Grüninger1, and M. Braden1 — 1Institute of Physics II, University of Cologne — 2Institute for Solid State Physics, The University of Tokyo — 3TU Munich, FRM-II, Garching — 4Institute for Materials Science, TU Darmstadt, Darmstadt — 5Hasylab/DESY, Hamburg
Transition metal oxides with only one or two electrons in the 3d-shell are particularily interesting, as diffraction may more easily isolate the impact of the active electrons. A) The vanadate AV2O5 shows a variety of low-dimensional phenomena. We confirm the persistence of charge ordering of LiV2O5 down to 2 K by single crystal neutron diffraction and present an electron density study. B) We were able to solve the complex, distorted tetragonal hollandite (K2V8O16) structure below the MI-transition at 175 K revealing a dimerization of the vanadium ions in one of two vanadium chains and a zig-zag-chain formation in the neighbouring chain. C) CaCrO3 is a d2 system with the unusual Cr oxidation state 4+. It appears to be a bad metal, as found in optical spectroscopy, but in contrast to most metallic transition metal oxides CaCrO3 orders antiferromagnetically with a pronounced structural anomaly occuring just at the Néel temperature. D) Cubic spinels AM2O4 with magnetic M ions have attracted strong attention due to intrinsic frustration. We determined the electron density of ZnV2O4.