CORRELATIONS OF SUPERCONDUCTIVITY, MAGNETIC ORDER AND HEAVY-FERMION IN PR-BASED CUPRATES

Electrical, magnetic and specific-heat properties of Pr-based cuprates , such as PrBa2-(Cu1-xGax)(3)O-7, Pr2CuO4, PrBa2Cu2NbO8, and PrSr2Cu2. 7Mo0.3O7 are presented and discussed. It was found that the value of n ormal state resistivity (such as rho(100 K) of these Pr-based cuprates is strongly correlated with the occurrence of superconductivity in th eir doped samples. Superconductivity occurs in doped Pr2CuO4 and PrSr2 Cu2.7Mo0.3O7 samples, which have a small rho(100 K) and a low T-N(< 0. 6 K). A small (similar to 3 mJ/Pr mol K-2) and a large (similar to 200 mJ/Pr mol K-2) values of gamma are observed in Pr2CuO4 and PrSr2Cu2.7 Mo0.3O7, respectively, which are independent of the occurrence of supe rconductivity in doped samples. No superconductivity is observed in an y samples with large rho(100 K) and high T-N(similar to 10 K), such as in PrBa2Cu2NbO8 and PrBa2Cu3O7. There are no apparent correlations am ong reduced mu(eff), high T-N, and large gamma in these Pr-based cupra tes. These results are discussed in conjunction with the hybridization between Pr 4f electrons and Cu-O-2 conduction bands in these unique P r-based systems.