Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.35: Poster

Wednesday, March 24, 2010, 14:00–18:00, Poster D1

Temperature dependent optical conductivity of RVO₃ (R=Y, Gd), LaSrFeO₄ and RCoO₃ (R=La, Eu) studied by ellipsometry — •Julia Küppersbusch¹, Kostiantyn Shportko¹, Agung Nugroho², Thomas Palstra², Navid Qureshi¹, Marco Reuther¹, Thomas Lorenz¹, and Markus Grüninger¹ — ¹Universität zu Köln — ²Rijksuniversiteit Groningen

Spin and orbital degrees of freedom play a decisive role in strongly correlated transition-metal oxides. Spin and orbital correlations for instance have a strong impact on the optical transitions from the lower to the upper Hubbard band. Our aim is a systematical study to understand the importance of spin/orbital correlations and also excitonic effects on the temperature dependence of the optical spectra. We use ellipsometry from 0.75 to 5.5 eV and show results on RVO₃, LaSrFeO₄, and RCoO₃.
The 3d⁵ configuration of LaSrFeO₄ does not show orbital degrees of freedom, the spins order at 350 K, thus the behavior at lower temperatures offers a reference for the influence of the lattice. The T dependence of the optical data of 3d² RVO₃ can be well described on the basis of spin/orbital correlations. The 3d⁶ compounds RCoO₃ allow to study the effect of a spin-state transition on the optical data.