Influence of Sr doping on the free carrier absorption in high-T
c
superconductors La2?x
SrxCuO4 |
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Authors: | H P Geserich D Sack G Scheiber B Renker D Ewert |
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Institution: | (1) Institut für angewandte Physik, Universität Karlsruhe, Kaiserstrasse 12, D-7500 Karlsruhe 1, Federal Republic of Germany;(2) Kernforschungszentrum Karlsruhe, Institut für Nukleare Festkörperphysik, Postfach 3640, D-7500 Karlsruhe 1, Federal Republic of Germany |
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Abstract: | The reflectance spectra of polycrystalline La2–x
Sr
x
CuO4 samples were investigated in the energy range between 50 meV and 4 eV in dependence of the Sr content. The spectra are attributed to free carrier absorption of the Drude type, superimposed by optical phonon excitations below 0.1 eV and intrinsic absorption above 1 eV. From the influence of Sr doping onto the plasma energy it is deduced that La2–x
Sr
x
CuO4 is ap-type conductor with a maximum carrier concentration of 2.0×1021 cm–3 forx=0.15. The results are interpreted in terms of a Hubbard model with an empty upper and ap-doped lower Hubbard band with a width of 1.9 eV. |
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Keywords: | |
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