Effect Melting Time on the Excess Conductivity and Critical Parameters of BSCCO Cooper Oxide System

We report here the effect of melting time (t(m)= 2.5-4.5 min) on the conductivity and dimensionality of BSCCO cooper oxide system. It is found that the mean field and crossover temperatures (T-c(mf), T-01, and T-02) are increased by increasing t(m)up to 3.5 min, followed by a decrease with further increase of t(m)up to 4.5 min. The logarithmic plots of excess conductivity ( increment sigma) and reduced temperature (CYRILLIC CAPITAL LETTER UKRAINIAN IE) reveal three regions of different exponents corresponding to two crossover temperatures in the slope of each plot. Interestingly, the crossover occurs from three dimensional (3D) to zero dimensional (0D/SW) in the mean field region and from 0D/SW to two dimensional (2D) in the critical field region, for the samples melted at t(m)= 2.5, 4, and 4.5 min, while it occurs from (3D) to one dimensional (1D) and from (1D) to (2D) for the sample melted at t(m)= 3.5 min. On the other hand, we have estimated several physical parameters such as order parameter exponents (lambda), interlayer coupling (K), c-axis coherence length (xi(c)(0)), anisotropy (gamma), Ginsburg number (G(i)), critical magnetic fields (H-c(0),H-c1(0), andH(c2)(0)), and critical current (J(c)(0)) for all samples. It is found that lambda(1), lambda(3),K, xi(c)(0),G(i), and gamma are increased by increasing t(m)up to 3.5 min, followed by a decrease with further increase of t(m)up to 4.5 min as well asT(c),T-c(mf), andT(0)behaviors. But the vice is versa for the behaviors of lambda(2), kappa,H-c(0),H-c1(0),H-c2(0),J(c)(0), andN(G). Moreover, it is observed that the behavior of critical fields and critical current against melting time is controlled by the order parameter exponent of the second region rather than the first and third regions. These results are discussed in terms of the correlation between the effects of melting time on the weak links and the flow of actual supercurrent in the considered system.