Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.51: Poster

Samstag, 5. März 2005, 11:00–16:30, Poster TU C

The electronic structure of La_1−xSr_xTiO_3+δ — •Alexander Gössling, Reinhard Rückamp, Holger Roth, Thomas Lorenz, and Markus Grüninger — II. Physikalisches Institut, Universität zu Köln

Transition-metal oxides with orbital degeneracy have attracted a lot of interest. Their optical conductivity shows multi-peak structures in the visible und ultraviolet energy range. These excitations have been attributed to interband transitions either into the upper Hubbard band or the charge-transfer band. The spectral weight of the transitions from the lower into the upper Hubbard band sensitively depends on orbital and magnetic correlations. In this way, the physics of high (∼ eV) and low (∼ meV) energies is intimately connected.

In this context we studied the effect of hole doping on the optical conductivity of the Mott-Hubbard insulator LaTiO₃ in the range of 0.7 to 6.4 eV across the metal-insulator transition by means of ellipsometry. Furthermore we compare the spectra with the data of YTiO₃, having a reduced bandwidth. Supported by the DFG through SFB 608.