Electronic Structure of Superconducting and Non-superconducting Pr_2Ba_4Cu_7O_<15-δ> Revealed by Photoemission Spectroscopy(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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In order to understand the nature of chain-driven superconductivity in Pr_2Ba_4Cu_7O_<15-δ> (Pr247), we have studied the electronic structure of as-sintered non-superconducting Pr247 and annealed superconducting Pr247 samples using photoemission spectroscopy. The O 1s, Ba 3d, Pr 4d, and Cu 2p core-level energy shifts by annealing indicate that electrons doped by the annealing mainly fill the localized Fehrenbacher-Rice (FR) state. The photoemission spectra ρ(ω) near the Fermi level (E_F) are derived from the metallic Cu-O double chain and can be fitted to the power-law function plus step function Aω^α+Bθ(ω). ρ(ω) near E_F is indistinguishable between the as-sintered and annealed Pr247 and the exponent α is 〜1.5. These results indicate that the Cu-O double chain provides the spectral weight near E_F and that the annealing affects the localized FR state instead of the near-E_F state.
社団法人日本物理学会の論文
2008-07-15