Analysis of fluctuation conductivity of polycrystalline Er1-xPrxBa2Cu3O7-δ superconductors

In this work we report on conductivity fluctuation measurements in polycrystalline samples of the Er1-xPrxBa2Cu3O7-δ superconductor (x =0.00, 0.05 and 0.10). Samples were prepared by a standard solid state reaction technique. The results were analyzed in terms of the temperature derivative of the resistivity and of the logarithmic temperature derivative of the conductivity that allowed the identification of power-law divergences of the conductivity. The results show that the transition proceeds in two stages: pairing and coherence transition. Also, our results, from the critical exponent analysis, show a two-peak splitting at pairing transition, indicating possibly a phase separation. On approaching the zero resistance state, our results show a power-law behavior that corresponds to a phase transition from para coherent to a coherent state of the granular array. (author)