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Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: Metal-Insulator Transition 2

TT 34.7: Talk

Thursday, February 28, 2008, 15:45–16:00, H 2053

Spectral weight distribution of d1 Mott insulators LaTiO3 and YTiO3H. Roth1, •T.C. Koethe1, Hua Wu1, Z. Hu1, A. Hendricks1, J. Gegner1, M.W. Haverkort1, T. Lorenz1, J.C. Cezar2, N.B. Brookes2, I.S. Elfimov3, G.A. Sawatzky3, and L.H. Tjeng11II.Physikalisches Institut Universität zu Köln — 2European Synchrotron Radiation Facility (ESRF), BP 220, 38043 Grenoble Cedex, France — 3Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada, V6T 1Z1

We have utilized bulk-sensitive photoelectron spectroscopy to study the valence band spectral weight distribution of d1 Mott insulators LaTiO3 and YTiO3. We observed appreciable differences in the spectra, reflecting the difference in the one-electron band width. We also found that the Ti 3d spectra of both materials are much broader than the occupied 3d bands calculated by band theories. The mean-field inclusion of the Hubbard U explains the band gap but produces even narrower bands, indicating the complete breakdown of standard mean-field theories in describing excitation spectra. We associate the observed spectra with the propagation of a hole in a system with surprisingly well suppressed charge fluctuations thereby showing characteristics of a t-J model.

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