Role of Mobile Charge Carriers and Fluctuation Induced Conductivity in (Cu0.5Tl0.5−xKx)Ba2Ca3Cu1Zn3O12−δ Superconductor

The main role played by mobile carriers and fluctuation induced conductivity (FIC) in (Cu0.5Tl0.5−x K x )Ba2Ca3Cu1Zn3O12−δ (x=0, 0.25) superconductor samples are analyzed in the light of the Aslamazov–Larken (AL) theory. The enhancement of three-dimensional (3D) conductivity and grain size is achieved with K-doping at Tl sites in the (Cu0.5Tl0.5−x K x )Ba2O4−δ charge reservoir layer, which are further improved by post-annealing the samples in oxygen. The improvement of these factors causes the increase in cross-over temperature (T o), zero resistivity critical temperature {T c(R=0)} and T c(onset) of diamagnetism to their higher values. We have also evaluated the exponents (λ 2D and λ 3D), zero temperature coherence lengths ξ c(0), and interlayer coupling (J) for these samples and tried to correlate them to the superconductivity order parameters.