Excess Conductivity and Critical Physical Parameters of Y Substituted Ca Site of Bi: 2223 High Tc Superconductors

Abstract

We presented here the fluctuation induced excess conductivity in Bi1.7Pb0.3Sr2Ca2-xYxCu3Oy superconductors with various x values (0.00 < x < 0.50). The logarithmic plots of excess conductivity (∆σ) and reduced temperature (ε) reveal three different values of the order parameter dimensional exponents against a decrease of temperature corresponding to two different values of crossover temperatures. In the critical field region, the order parameter exponents are two dimensional (2D) as x increases up to 0.20, but it is changed to three dimensional (3D) with further increase of x up to 0.50. While, the order parameter exponents are not systematic with Y in both normal and mean field regions, and they are fluctuated between zero dimensional /short wave (0D/SW), qusi-2D, qusi-1D and 3D. On the other hand, the coherence lengths, inter-plane spacing, interlayer coupling, G-L parameter and anisotropy are calculated and their values are generally increased by increasing x up to 0.50, whereas G-L parameter, Ginsburg number, critical magnetic fields and critical current density are decreased. The possible reasons for the above findings are also mentioned.