Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 31: Correlated Electrons: Metal Insulator Transition - Part 2

TT 31.2: Vortrag

Donnerstag, 30. März 2006, 14:15–14:30, HSZ 301

Electronic structure of LaTiO₃ and YTiO₃ — •A. Gössling¹, R. Rückamp¹, H. Roth¹, T. Lorenz¹, A. Freimuth¹, and M. Grüninger² — ¹II. Phys. Institute, University of Cologne, Germany — ²II. Phys. Institute, University of Aachen, Germany

In Mott-Hubbard insulators, excitations from the lower to the upper Hubbard bands give rise to an interesting multi-peak structure in the optical conductivity. The spectral weight of these features is very sensitive to magnetic and orbital correlations.

Using spectroscopic ellipsometry, we determined the optical conductivity σ between 0.8 and 6 eV of the Mott-Hubbard insulators YTiO₃ and LaTiO₃ as function of temperature. While the spectra of YTiO₃ show a sizeable redistribution of spectral weight with temperature, those of LaTiO₃ are almost temperature independent. In YTiO₃ a strong anisotropy between σ_a,b and σ_c is observed, which we trace back to an orbitally-ordered ground state.

Supported by the DFG in SFB 608