Observation of Magnetic Flux Generated Spontaneously During a Rapid Quench of Superconducting Films

Abstract

We report observations of spontaneous formation of magnetic flux lines during a rapid quench of YBa${}_2$Cu${}_3$O${}_{7-\delta }$ films through T${}_c$. This effect is predicted according to the Kibble-Zurek mechanism of creation of topological defects of the order parameter during a symmetry-breaking phase transition. Our previous experiment, at a quench rate of 20K/sec, gave null results. In the present experiment, the quench rate was increased to \TEXTsymbol{>} 10${}^8$ K/sec. Within experimental resolution, the dependence of the measured flux on the cooling rate is consistent with the prediction.