Fluctuation conductivity in melt-textured REBa2Cu3O7-δ superconductors

We have studied fluctuations on the electrical conductivity in melt-textured REBa2Cu3O7-δ superconductors, where RE corresponds to a natural mixture of rare earth elements extracted from xenotime mineral. For this study, melt processed samples were prepared using the top seeding growth technique. To identify power-law divergences of the conductivity, the results were analyzed in terms of the temperature derivative of the resistivity and of the logarithmic temperature derivative of the conductivity. The data revealed the occurrence of a two-stage intragranular-intergranular transition. In the normal phase, different Gaussian and critical regimes were clearly observed to each current direction. Such an observation reveals that there is an evidence for anisotropies effects in studied conductivity regimes. Finally, the results obtained showed that the fluctuation conductivity in melt-textured samples of REBa2Cu3O7-δ is very similar to those observed in YBa2Cu3O7-δ