Electrical and thermal properties of bulk superconductors Eu0.95Pr0.05Ba2(Cu1-xMx)(3)O7-delta (M = Fe, Ni, Zn and Mn)

摘要

Measurements of transition temperature, magneto-resistance, thermal conductivity, thermo-electric power and specific heat have been carried out on co-doped samples of Eu0.95Pr0.05Ba2(Cu1-xMx)(3)O7-delta (M = Fe, Ni, Zn and Mn) compounds It is found that all samples exhibit metallic behavior, except the co-doped sample of Fe that shows semiconducting behavior It is seen that the upper-critical field Ho decreases with Pr-doping However, an increase in H-c2 for dopants like Fe and Mn is observed Thermal conductivity for the pristine sample of EuBa2Cu3O7-delta (Eu-123) exhibits a pronounced hump below the superconducting transition temperature T-c However, the peak height of the hump decreases with Pr-doping and such a feature is further suppressed in the co-doped samples The negative sign of the measured thermo-electric power of Eu-123 indicates that the dominant carrier in this sample is electron-like, whereas it turns to hole-like for all of the doped samples A Jump in specific heat C-p is detected in the pure sample of Eu-123 at T-c, while only a change in slope in C-p is seen around the transition temperature in the Pr-doped sample.