Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 22: Postersitzung III: Syst. korr. Elektr.: Theorie II (1-15), Metall-Isol.- und Phasenüberg
änge (16-33), SL: Massivmat., Bandl., Pinning, Vortexdyn., Transport, Korngr. (34-43), Niedrigdim. Syst., Magnetotransport (44-63)

TT 22.17: Poster

Donnerstag, 14. März 2002, 14:00–17:30, A

Structural and magnetic aspects of the metal-insulator transition in Ca2−xSrxRuO4 — •O. Friedt1,2, M. Braden2, G. André1, P. Adelmann3, S. Nakatsuji4, and Y. Maeno4,51Laboratoire Léon Brillouin, CEA/CNRS, F-91191 Gif-sur-Yvette — 2II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln — 3Forschungszentrum Karlsruhe, IFP, Postfach 3640, D-76021 Karlsruhe — 4Departement of Physics, Kyoto University, Kyoto 606-8502, Japan — 5CREST,Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan

We have studied the phase diagram of Ca2−xSrxRuO4 over the whole region of x by neutron scattering on powder and crystalline samples. The experiments reveal antiferromagnetic order and structural distortions of the K2NiF4 structure type characterized by tilts and rotations of the RuO6 octahedra. Our results strongly suggest that the structural distortions of the isovalent samples tune the magnetic as well as the electronic behaviour. In particular we observe for low Sr concentrations (x<0.2) characteristic changes of the Ru-O bonds and tilt angles which are associated with a metal-insulator transition and AFM-ordering. Further the suppression of the tilt distortion, observed for xc≃ 0.5, is accompanied by a critical increase of low temperature susceptibility. Additionally we present the phonon dispersion and the magnetic excitations close to xc.

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