Effect of Fluctuations on Electronic Properties above the Superconducting Transition

Abstract

A calculation of the microscopic effects of the fluctuations of the superconducting order parameter in the classical region above ${T}_{c}$ on the electron Green's function in dirty materials is presented. The calculation is formulated in the presence of a magnetic field. The results of this calculation in the zero-field limit are used to obtain the change in the thermal conductivity $K$ and in the electron density of states $N(\ensuremath{\omega})$. For a one-dimensional sample, $K$ appears to diverge as ${[\frac{(T\ensuremath{-}{T}_{c})}{{T}_{c}}]}^{\ensuremath{-}\frac{1}{2}}$ while for two and three dimensions, $K$ depends weakly on temperature. The behavior of $N(\ensuremath{\omega})$ is qualitatively similar to that of a gapless superconductor below its transition temperature, although the detailed frequency dependence is different. For thin films, the depression at the Fermi surface increases as ${[\frac{(T\ensuremath{-}{T}_{c})}{{T}_{c}}]}^{\ensuremath{-}2}$. The agreement with experiment is satisfactory.