Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.111: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Role of the structural distortions in the phase diagrams of RE1−xAxTiO3 (A=Ca,...) — •A. C. Komarek1, M. Cwik1, W. D. Stein1, H. Roth1, H. Hartmann1, T. Zabel1, M. Kriener1, N. Schittner1, A. El-Filali1, M. Hölzel2, F. Bouree3, T. Lorenz1, A. Freimuth1, and M. Braden1 — 1II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln — 2Technische Universität Darmstadt, c/o Technische Universität München — 3Laboratoire Leon Brillouin, CE-Saclay, F-91191 Gif-sur-Yvette, France
Having one electron in the 3d shell, the rare earth (RE) titanates RETiO3 represent interesting systems to study the complex interplay of orbital and magnetic degrees of freedom as well as to investigate metal-insulator (MI) transitions enabled by hole doping due to a partial substitution of the trivalent rare earth by divalent earth alkaline ions. In the series of rare earth titanates we find an anomalous behaviour of the lattice parameter a for the samples with larger rare earth ions showing antiferromagnetic order. However, with decreasing rare-earth ionic radius the anomalous increase of the lattice constant a gets even more pronounced and sets in closer to the magnetic ordering temperature. The hole-doped system Y1−xCaxTiO3 shows a complex phase diagram of structural transitions. The structural changes are accompanied by a MI transition and anomalies in the magnetic susceptibility. We ascribe this complex behavior to the coexistence of an insulating monoclinic phase and a metallic low-temperature orthorhombic phase. Our neutron diffraction data give evidence for a charge ordering in the monoclinic phase.