Electronic Structure of the Quenched Superconductivity Materials Y/sub 1-X/Pr/sub X/Ba sub 2 Cu sub 3 O/sub 7-delta/.

摘要

The superconductivity of the Y/sub 1-x/Pr/sub x/Ba sub 2 Cu sub 3 O/sub 7-delta/ system is quenched as x increases. It has been speculated that Pr has valence 4+, resulting in extra charge in the Cu-O planes, and causing T/sub c/-quenching. To study the Pr electronic state, we have measured valence band resonant photoemission of the Y/sub 1-x/Pr/sub x/Ba sub 2 Cu sub 3 O/sub 7- delta/ system for x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. We find that the Pr valence is close to 3+ for all x and that the extracted Pr 4f spectral weight has a complex lineshape, implying extensive Pr 4f/O 2p hybridization which probably causes the T/sub c/-quenching by disrupting the electronic or magnetic structure of the x = 0 material, perhaps via a Pr-Cu superexchange interaction. 36 refs., 4 figs. (ERA citation 13:049061)