Photoemission Electronic States of Thallium- and Bismuth-Based Superconductors

R. Zaleckia, A. Kołodziejczyka, J.W. Königb and G. Gritznerb aUniversity of Mining and Metallurgy, Faculty of Physics and Nuclear Technique Al. A. Mickiewicza 30, 30-059 Cracow, Poland bJohannes Kepler Universität, Institut für Chemische Technologie Anorganischer Stoffe 4040 Linz, Austria

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X-ray photoemission spectra the core-levels as well as the X-ray photoemission spectra and ultraviolet photoemission spectra from the valence bands of the (Tl0.6Pb0.5)(Sr0.9Ba0.1) Ca2Cu3Oy and (Bi1.75Pb0.35)Sr1.9Ca2.05Cu3.05Oy superconductors were measured and analyzed. Special attention was paid to the valence band X-ray photoemission spectra and ultraviolet photoemission spectra, the Cu 2p core-level X-ray photoemission spectra and the Cu L2,3-M4,5M4,5 and O K-L2,3L2,3 Auger spectra. Both Cu 2p3/2 and Cu 2p1/2 core-level lines consisted of two spin-orbit split main lines accompanied with the two satellite lines. The charge transfer energy Δ from the oxygen ligand to the copper 3d9 states and the hopping integral t were estimated from the energy separation between the main line and the satellite line taking advantage of the local cluster model calculations and their extension to high-temperature superconductors. The Coulomb correlation on-site energy Udd of two electrons in the same copper orbital and Upp of two electrons in the oxygen orbital as well as the correlation energy Ucd of the 2p core hole - 3d electron interaction have been estimated from the Auger electron spectra and the valence band spectra. They are: Udd=6.0±0.5eV, of Upp≅ 10±1eV and of Ucd≅ 8.0±0.5eV nearly the same for both the Tl- and Bi-compounds. We conclude that these compounds are the charge transfer strongly-correlated metals.

DOI: 10.12693/APhysPolA.98.513 PACS numbers: 74.72.-h, 79.60.-i