The effect of fluctuations on the electrical transport behavior in YBa2Cu3O(7-x)

prepared by both coevaporation and laser ablation has been studied in detail in the n_luced-temperature range 9 x 10 -4 < t < 1. The exces_ conductivity in all the films studied was found to diverge sharply near To, in agreement with the conventional mean-field thoery. However, the detailed temperature dependence could not be fitted to either the power-law o¢ the logarithmic functional forms as predicted by the theory. The excess conductivity of all the films was found to be o[ponentially dependent on the temperature over nearly three decades for 9 × 10 -4 < t < 10 -1, in contradiction to the mean-field theory. The rounding of the superconducting phase transition has been conventionally attributed to fluctuations in the magnitude and lifetime of the order parameter. By considering fluctuations of magnitude less than the order parameter in the GinzburgLandau (GL) theory, a critical temperature region was predicted in which the OL theory will not be valid. For temperatures greater than the critical limit the excess contribution Act to electrical conductivity is estimated using the mean-field value of the order parameter in the time-dependent GL (TDGL) theory. The excess conductivity A_, is defined as crexp - c7c_1¢ where cTex p is the experimentally observed electrical conductivity and or, to the conductivity due to normal-electron scattering alone in the absence of superconducting fluctuations. It is found to follow a power-law-type temperature dependence given by