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 22.16: Poster
Donnerstag, 14. März 2002, 14:00–17:30, A
Evidence for an unconventional metal-insulator transition in copper-oxygen superconductors — •Matthias Opel1, Francesca Venturini1, Thomas P. Devereaux2, Jim K. Freericks3, István Tüttő4, Bernard Revaz5, Eric Walker5, Helmuth Berger6, László Forró6, and Rudi Hackl1 — 1Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — 2University of Waterloo, Waterloo, Canada N2L 3G1 — 3Georgetown University, Washington, DC 20057, USA — 4Research Institute for Solid State Physics and Optics, 1525 Budapest, Hungary — 5Université de Genève, 1121 Genève, Switzerland — 6Ecole Polytechnique Fédérale, 1025 Lausanne, Switzerland
Strong electronic correlations determine the properties of copper- oxygen compounds, and a complex phase diagram develops upon doping that contains long-range antiferromagnetic order, magnetic fluctuations, charge and spin ordering, pseudogap behaviour, and superconductivity. The interrelation of the various instabilities is among the important open problems in solid state physics. Here we examine the metallic state at temperatures well above the superconducting transition using Raman scattering as an energy and momentum sensitive many-particle probe of the electron dynamics. We present results of Bi-2212 single crystals covering a wide range of effective doping p. We observe a strong variation with momentum of the electron dynamics that rapidly disappears at a doping level p ≃ 0.22. We show that this is not an effect of the single-particle lifetime but rather of a generalized metal- insulator transition with a momentum and doping dependent gap.