FLUCTUATION CONDUCTIVITY ABOVE THE SUPERCONDUCTING TRANSITION - REGULARIZATION OF THE MAKI-THOMPSON TERM

The Maki-Thompson (MT) fluctuation correction to the conductivity in impure electron systems close to the superconducting transition temperature T(c) is reconsidered. It is shown that the results of earlier works concerning the case when the pair breaking is due to the electron-electron interaction in the Cooper channel are incorrect. The essential point of our calculations is that the electron phase-relaxation rate due to the electron-electron interaction in the Cooper channel is a singular function of the electron frequency. This singularity, which was missed in earlier works, indicates strongly interacting fluctuations near the transition temperature. According to our results the MT correction close to the transition temperature is less singular than the Aslamazov-Larkin (AL) correction. A little farther from the transition both corrections are the same order, e.g., close to transition in the two-dimensional case, the MT correction is proportional to 1n-alpha, where alpha = (T-T(c))/T(c), while the AL correction is proportional to alpha-1. We also consider the magnetoconductivity close to the transition temperature in the two-dimensional case.