Mechanism of suppression of superconductivity in (PrxY1−x)Ba2Cu4O8

The effect of Pr on the superconductivity in (Pr x Y 1−x )Ba 2 Cu 4 O 8 were studied and compared with that in (Pr x Y 1−x )Ba 2 Cu 3 O 7 . Transition temperatures of the (Pr x Y 1−x )Ba 2 Cu 4 O 8 compounds decrease with increasing Pr content x, although the rate of decrease is slower than that of (Pr x Y 1−x )Ba 2 Cu 3 O 7 . Thus the Pr has a weaker effect to the superconductivity suppression in (Pr x Y 1−x )Ba 2 Cu 4 O 8 than in (Pr x Y 1−x )Ba 2 Cu 3 O 7 . From the analysis of X-ray absorption spectra(XAS) near O K-edge in (Pr x Y 1−x )Ba 2 Cu 4 O 8 and in (Pr x Y 1−x )Ba 2 Cu 3 O 7 , the effect of Pr substitution on the O 2p electronic state is found to be weaker for (Pr x Y 1−x )Ba 2 Cu 4 O 8 , which is parallel to the effect on superconductivity. These results were well explained with the hole localization model based on the hybridization of Pr 4f and O 2p orbitals.