Microwave Conductivity of Granular Aluminum Films in the Superconducting Transition Region

Abstract
Data are presented on the resistivity of granular aluminum films near the superconducting transition temperature Tc for both dc and 20-GHz excitation. Comparison with a recent theory of the effect of fluctuations on the frequency-dependent resistivity above Tc shows much less excess conductivity than predicted. A possible explanation for the discrepancy may lie in the incorrectness of a currently suggested form for the time-dependent Ginsburg-Landau equation.