5 research outputs found
Search for Spontaneous Nucleation of Magnetic Flux During Rapid Cooling of YBCO films Through Tc
We describe an experimental search for spontaneous formation of flux lines
during a rapid quench of thin YBaCuO films through Tc. This effect is expected
according to the Kibble-Zurek mechanism of a creation of topological defects of
the order parameter during a symmetry breaking phase transition. Spontaneously
formed vortices were previously observed in superfluid 3He, while a similar
experiment in superfluid 4He gave negative results. Using a high Tc SQUID, we
measured both the magnetic flux in the sample during a quench with a
sensitivity of 20 phi-0/cm^2, and the field noise which one would expect from
flux lines pinned in the film. The sensitivity was sufficient to detect
spontaneous flux at a level corresponding to 10^(-3) of the prediction. Within
our resolution, we saw no evidence for this effect.Comment: Manuscript and 4 figure