Thermally activated spontaneous fluxoid formation in superconducting thin film rings

The formation of spontaneous fluxoid generation in thin film rings of the amorphous superconductor Mo3Si was reported. The superconductor was cooled through the normal-superconducting transition, as a function of quench rate and externally applied magnetic field, using a variable sample temperature scanning superconducting quantum interference device (SQUID) microscope. The results were explained using a model of freeze-out of thermally activated fluxoids, mediated by the transport of bulk vortices across the ring walls.