Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 86: Correlated Electrons: Other Materials
TT 86.9: Vortrag
Donnerstag, 3. April 2014, 11:45–12:00, BEY 81
HAXPES study of the spectral weight distribution of d1 Mott insulators LaTiO3 — •Jonas Weinen1, Stefano Agrestini1, Alexander C. Komarek1, Zhiwei Hu1, Thomas Koethe2, Maurits W. Haverkort1, Yen-Fa Liao3, Ku-Ding Tsuei3, and Liu H. Tjeng1 — 1Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden — 2II. Physikalisches Institut der Universität zu Köln — 3National Synchrotron Radiation Research Centre, Hsinchu, Taiwan
Using hard x-ray photoelectron spectroscopy (HAXPES) we have obtained bulk-sensitive valence band spectra of the d1 Mott insulators LaTiO3 and YTiO3. The experiment was performed in the s polarization, thus suppressing the s orbitals spectral weight which hide the d orbitals when using the more common p polarization.
We observed appreciable differences between the spectra of the two compounds, 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 meanfield 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.