Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 31: Correlated Electrons: Metal Insulator Transition - Part 2
TT 31.8: Talk
Thursday, March 30, 2006, 15:45–16:00, HSZ 301
New perspectives on charge ordering phenomena in complex transition-metal oxides — •Y. Su1, H.F. Li1, A. Nefedov2, J. Persson1, P. Meuffels1, J. Grabis2, H. Zabel2, D. Wermeille3, V. Kaiser4, D. Schrupp5, R. Claessen5, V.A.M. Brabers6, D. Prabhakaran7, A.T. Boothroyd7, P.D. Hatton8, and Th. Brueckel1 — 1Institut für Festköperforschung, Forschungszentrum Juelich, D-52425 Juelich — 2Inst. für Experimentalphysik IV, Ruhr-Universität Bochum — 3MuCAT, Advanced Photon Source, Argonne National Laboratories — 4Inst. für Kristallographie, RWTH — 5Experimental Physik IV, Universität Wüzburg — 6Dept. of Phys., Eindhoven University of Technology — 7Dept. of Phys., Univ. of Oxford — 8Dept. of Phys., Univ.of Durham
New insights on the nature of charge ordering in transition-metal oxides (TMO) have been gained via the latest resonant scattering experiments carried out in both soft ( < 1 KeV) and hard ( ~ 8 KeV) X-ray regimes on high-quality single crystals of lightly hole-doped La7/8Sr1/8MnO3 and mixed-valence Fe3O4. A giant resonance at the oxygen K absorption edge has been observed from the charge ordering superstructure reflections of both compounds, suggesting that the charge ordering is strongly associated with a spatial modulation of ligand-hole states near the Fermi surface. Comprehensive data obtained at the corresponding L3/L2 and K-edges also strongly supports this scenario. These investigations not only allow us to resolve the long-standing puzzles concerning the nature of the Verway transition, but also indicate that the localized ligand holes might be a key ingredient for many charge-transfer type TMO.