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Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.72: Poster

Saturday, March 5, 2005, 11:00–16:30, Poster TU C

Structural properties of RETiO3 and Y1−xCaxTiO3 — •A. Komarek1, H. Roth1, T. Lorenz1, W.D. Stein1, M. Cwik1, F. Bourée2, A. Freimuth1, and M. Braden11II. Physikalisches Institut, Universität zu Köln — 2Laboratoire Léon Brillouin

We have studied the crystal structure of the RETiO3 by different diffraction techniques as function of temperature. In all compounds we find significant distortions of the TiO6-octahedra which lead to a lifting of the t2g-orbital degeneracy. A comparison with literature data on isostructural compounds with a 3d0 or a 4d0-configuration shows that such distortions not necessarily are caused by orbital physics. In the RETiO3-series, however, the temperature dependence clearly points to a direct coupling. The octahedron distortions depend more sensitively on temperature than the tilt and rotation angles; and, in particular, we find strong anomalies at the Néel-temperatures in all antiferromagnetic RETiO3 compounds.

Neutron diffraction on a sample of Y0.62Ca0.38TiO3 yields strong evidence for charge ordering, which may be the key element to understand, why Ca-doped YTiO3 stays non-metallic till rather high doping.

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