MECHANISM OF SUPPRESSION OF SUPERCONDUCTIVITY IN (PRXY1-X)BA2CU4O8

The effect of Pr on the superconductivity in (PrxY1-x)Ba2Cu4O8 were st udied and compared with that in (PrxY1-x)Ba2Cu3O7. Transition temperat ures of the (PrxY1-x)Ba2Cu4O8 compounds decrease with increasing Pr co ntent x, although the rate of decrease is slower than that of (PrxY1-x )Ba2Cu3O7. Thus the Pr has a weaker effect to the superconductivity su ppression in (PrxY1-x)Ba2Cu4O8 than in (PrxY1-x)Ba2Cu3O7. From the ana lysis of X-ray absorption spectra(XAS) near O K-edge in (PrxY1-x)Ba2Cu 4O8 and in (PrxY1-x)Ba2Cu3O7, the effect of Pr substitution on the O 2 p electronic state is found to be weaker for (PrxY1-x)Ba2Cu4O8, which is parallel to the effect on superconductivity. These results were wel l explained with tile hole localization model based on the hybridizati on of Pr 4f and O 2p orbitals.