RESISTIVE TRANSITION AND FLUCTUATION CONDUCTIVITY IN BI2SR2CACU2O8-CRYSTALS(DELTA SINGLE)

Detailed resistivity measurements were made along the planes of Bi2Sr2 CaCu2O8+delta single crystals in zero field and in the temperature reg ion above the superconducting transition temperature T-c. Analyses of the fluctuation conductivity Delta sigma are presented using a careful construction of the mean-field critical temperature T-c(mf). Delta si gma can be described by the Lawrence-Doniach model with a two-dimensio nal (2D)-3D crossover close to T-c(mf). The c-axis coherence length wa s found to be 0.9 +/- 0.1 Angstrom. For comparison Delta sigma was als o calculated from T-c defined from the peak temperature of d rho/dT. I t is shown that a consistent description of the 2D-3D transition is th en lost.