Cooperative phenomena in vortex motion in thin granular superconducting films

Abstract

Interaction between magnetic vortices may result in strong thermo-galvano-magnetic effects in thin superconducting films, whose thickness is much smaller than London penetration length. In particular, the Nernst coefficient acquires a contribution compared to that observed in semiconductors. The non-equilibrium vortex-antivortex pair production by some external currents anticipated to occur easily in granular films may lead to the same order of magnitude for the transverse voltage as provided by the Nernst effect. External microwave radiation absorbed inhomogeneously and resulting in a gradient of normal excitations along the film should cause the vortices motion and, consequently, the dc-voltage across the film. These strong effects are to be observed within the range of parameters where the Charged 2D Coulomb Gas Model is still valid. The connection of the results with the experiments of Gerber and Deutcher is discussed. The authors suggest to employ the effect of photoinducing the vortices motion in thin superconducting films to detect weak microwave radiation.