Excess conductivity in Cu0.5Tl0.5Ba2(Ca2-yMgy)(Cu0.5Zn2.5)O10-δ superconductor

Synthesis and characterization of Cu0.5Tl0.5Ba2(Ca2-yMgy)(Cu0.5Zn2.5)O10-delta (y=0, 1.0, and 1.5) superconductor with 0%, 50%, and 75% Mg-doping at the Ca sites are reported. The samples were synthesized by solid-state reaction and characterized by X-ray diffraction (XRD), dc-resistivity (rho) and fluctuation induced conductivity (FIC) analysis. The zero resistivity critical temperature {T-c(R=0)} was decreased with the increase of Mg-doping at Ca sites. The microscopic parameters such as the cross-over temperature (T-o), zero temperature coherence length {xi(c)(0)} and interlayer coupling (J) were deduced from FIC analysis. According to Aslamazov Larkin equations, a distinct cross-over temperature (T-o1) from three-dimensional (3D) to two-dimensional (2D) fluctuation induced conductivity regions was observed in all samples. Another crossover temperature (T-o2) from 2D to zero-dimensional (0D) fluctuations was also witnessed. FIC analysis revealed the deterioration of superconductivity with increased Mg-content. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.