Different regions of fluctuation conductivity in Sn-doped Cu0.5Tl0.5Ba2Ca2Cu3−ySnyO10−δ superconductors

Fluctuation induced conductivity of Cu0.5Tl0.5Ba2Ca2Cu3−ySnyO10−δ superconductors have been studied from the resistivity vs. temperature data. The logarithmic plots of excess conductivity (Δσ  ) vs. reduced temperatures [ε=(T−Tcmf)/Tcmf] show two crossover temperatures with three exponents. A distinct cross-over from two-dimensional to three-dimensional conductivity in accordance with the 2D, 3D Aslamazov–Larkin equations have been observed in all the samples. Another cross over from 2D to 0D fluctuations has also been witnessed. The FIC data fits well with 3D, 2D and 0D fluctuations for lower Sn doping, while it deviates considerably for higher Sn concentration. Also the FIC analysis shows the deterioration in quality of samples (increased ΔTc), increase in anisotropy and decrease in inter-layer coupling strength J with increased Sn content. These factors might be contributing to the suppression of Tc in these samples.