Accumulation and release of self-field generated vortices in percolative YBa2Cu3O7-delta-films

Pulsed laser heating of current biased percolative YBa2Cu3O7-delta-films ca n be used to generate and release self-field induced vortices. A laser puls e yields a voltage signal due to penetration of bias current induced magnet ic flux in absence of an external magnetic field. Upon recooling, strongly pinned vortices remain in the film. These remanent vortices have been detec ted after disconnecting the bias source in the currentless film. Applying a subsequent second laser pulse, again yields a signal voltage but of invers e sign due to magnetic flux redistribution.