Scaling behavior of resistivity tails at the edge of superconducting transition in Bi2Sr2CaCu2O8+$?$ epitaxial films

The behavior of the resistivity just below the mean-field transition temperature has been investigated in Bi2Sr2CaCu2O8+$?$ epitaxial films with various oxygen contents. Analysis of the temperature dependence of the resistivity was performed in terms of the Kosterlitz-Thouless charge-unbiding theory and the Ginzburg-Landau Coulomb-gas model for vortex fluctuations. A crossover from two- to three-dimensional vortex configuration was observed as the temperature approaches the Kosterlitz-Thouless transition temperature from above. The carrier mean free path and the effective interplane coupling as well as their dependences on the oxygen content were evaluated.