Dynamically enhanced supercurrents in granular superconducting Y-Ba-Cu-O thin films

Thin superconducting films of Y-Ba-Cu-O withT c0≊89 K have been prepared by the aerosol deposition method. The voltage current characteristic of microbridges (typically 10×10µm2) made from the finely granular films, which behave like a network of boundary Josephson junctions, is highly nonlinear and shows besides thermal effects evidence for dynamic enhancement of the supercurrent. Our experimental data are in qualitative agreement with a theory developed for conventional superconductors by Aslamazov and Larkin and also by Tinkham. A value for the electron phonon scattering time has been derived: τ E ≊15 ps.