Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Postersitzung I: Anwendungen der Supraleitung (1-6), Dünne Schichten, Josephsonkontakte, SQUIDs (7-17), Neue und unkonv. Supraleiter(18-23), Amorphe- und Tunnelsyst. (24-28), Quantenflüssigkeiten (29-30), Syst. korr. Elektr.: Theorie I (31-45)

TT 7.39: Poster

Montag, 11. März 2002, 14:30–18:00, A

Doped holes in edge-shared CuO₂ chains and the dynamic spectral weight transfer in x-ray absorption spectroscopy — •S.-L. Drechsler¹, Z. Hu¹, J. Málek^1,2, H. Rosner³, R. Neudert¹, M. Knupfer¹, M.S. Golden¹, J. Fink¹, J. Karpinski⁴, G. Kaindl⁵, C. Hellweg⁶, and Ch. Jung⁶ — ¹Institut für Festkörper- und Werkstofforschung, D-01171 Dresden, Postfach 270116, Germany — ²Institute of Physics, ASCR, Czech Republic — ³Dept. of Physics, University of California, Davis, USA — ⁴Laboratorium für Festkörperphysik, ETH Zürich , Switzerland — ⁵Institut für Experimentalphysik, Freie Universität Berlin — ⁶BESSY GmbH, Berlin

We present a joint experimental and theoretical study of the electronic structure of the chain compounds A_1−xCuO₂(A=Ca,Sr,Ba) using O-K and Cu-L₃ x-ray absorption spectroscopy.The doping-dependent behaviour in these systems differs from that of conventional 2D Cu-O networks formed by corner-shared CuO₄ plaquettes. It follows from the strongly weakened inter-plaquette hybridisation due to the nearly 90^∘ Cu-O-Cu bond in the chains. Spectroscopically, this results in (a)the different final states in the Cu-L₃ spectra which can be used directly to ’read-off’ the Cu valency and (b) a drastic reduction in the dynamic spectral weight transfer from the upper Hubbard band to the low-energy scale in the O-K spectra.