Fluctuation induced conductivity analyses of Cd doped Cu0.5Tl0.5Ba2Ca2Cu3−yCdyO10−δ (y=0, 0.5, 1.0, 1.5) superconductors

Fluctuation induced conductivity (FIC) analyses in the critical fluctuations region (cr), three dimensional (3D), two dimensional (2D) and zero dimensional (0D) region are reported for Cd-doped (Cu0.5Tl0.5)Ba2Ca3(Cu3−yCdy)O10−δ (y=0, 0.5, 1.0, 1.5) superconductors. The coherence length along c-axis, ξc(0), Fermi velocity, VF, and Fermi energy of the carriers, EF, were calculated from such analyses. Using the cross-over temperature (TG) of critical to 3D regime the Ginzberg number, NG, is determined. By using NG, thermodynamic critical field, Bc(0), the lower critical field, Bc1(0), and critical current density, Jc(0), are extracted. It was found from these analyses that widths of critical and 3D regimes are shrunken with the increased doping of Cd in the final compound. Also ξc(0), VF and the coupling constant J are suppressed with increased Cd doping. The decrease in important superconductivity parameters is suggested to be arising due to anharmonic oscillations induced by the heavier Cd atoms doped at Cu planar sites which in turn suppress the density of the desired phonons required for optimum superconducting properties. In these analyses we found that the critical magnetic fields (Bc(0), Bc1(0)) and Jc(0) increase with increased Cd concentration. The most likely reason for the improvement of magnetic properties is increased population of spin-less Cd atoms from which the magnetic field lines are not deflected and behave like pinning centers.