Fluctuation-Induced Conductivity of Cu0.5Tl0.5Ba2Ca2Cu2M1O10-δ (M = Si, Sn, Ge) Superconductors

Fluctuation-induced conductivity of Cu0.5Tl0.5Ba2Ca2Cu2M1O10-delta (M = Si, Sn, Ge) superconductors has been studied from the resistivity vs. temperature data. The logarithmic plots of excess conductivity (Delta sigma) vs. reduced temperatures [epsilon = ( T - T-c(mf))/T-c(mf)] show two crossover temperatures with three exponents. A distinct crossover from two-dimensional to three-dimensional conductivity in accordance with the 2D, 3D Aslamazov-Larkin equations has been observed in all the samples. Another crossover from 2D to 0D fluctuations has also been witnessed. FIC data analysis has been found to be quite useful in explaining the superconducting properties of the samples. Si and Sn doped samples have shown almost similar characteristics, while in Ge doped sample diverse behavior is observed.