Conductivity fluctuation in HBCCO superconductor

We have analyzed the measured excess conductivity of a HBCCO high- T c superconductor as a function of temperature, which is attributed to the fluctuation of superconducting order parameter above T c0 . This excess conductivity is consistent with the two dimensional Aslamazov-Larkin mean-field theory based on the Ginzburg-Landau theory. Applying the Lawrence-Doniach theory, we found that the interlayer coupling stregth is very small, and that a 2D to 3D crossover is not found down to ( T- T c0 )/ T c0 = 0.015. This two-dimensional fluctuation seems to be intrinsic to this highly anisotropic layered superconductor.