Resumen de Fluctuation-induced conductivity of polycrystalline (formule) superconductor
M. Murer, Y. Aparecido Opata, J.F.H. Leandro Monteiro, S. Aparecida da Silva, P. Rodrigues Júnior, A.R. Jurelo
This paper reports on measurements of the resistive transition in polycrystalline (formule) samples (x=0.000. 0.025 and 0.050). The samples were produced by a standard solid state reaction method and in two different thermal routes. The microstructure was analyzed by X-ray diffraction. The samples were considered homogeneous since no extra peaks due to impurity phase were observed. To identify power-law divergences in conductivity, the results were analyzed in terms of the temperature derivative of the resistivity and the logarithmic temperature derivative of the conductivity (formule). From the results, the occurrence of a two-stage transition besides the pairing transition splitting for sample with x=0.050 was observed. Such splitting was associated with Ce doping and related with the occurrence of a phase separation. In the normal phase, Gaussian and critical fluctuations conductivity regimes were identifies. On approaching the zero resistance state, our results showed a power-law behavior that corresponds to a phase transition from a paracoherent to a coherent state of the granular array.
