The transport coefficients in (R1.5Ce0.5)RuSr2Cu2O10-5 (R=Gd,Eu) rutheno-cuprates

Abstract

The thermal conductivity, thermopower, and electrical resistivity of (R1.5Ce0.5)RuSr2Cu2O10-delta (R=Gd, Eu) polycrystalline samples with different oxygen doping level are investigated in temperature range 1.8-300 K. Much attention is focused on the dependence of the effect of the annealing in high oxygen pressures as well as the effect of aging on transport coefficients in normal and superconducting states. It was found that the process of deoxydation goes faster for Ru-1222(Eu) samples than for Ru- 1222(Gd) samples, which results in more pronounced granular effects in Ru-1222(Eu) samples. The relative contribution to the thermal conductivity due to electrons and phonons was estimated by using the Wiedemann-Franz relation and the resistivity data. The calculation showed that the maximum electron contribution for Ru-1222(Eu) is about 0.75% and that for Ru-1222(Gd) samples is around 4 %.