St. Stoddart et al., QUANTUM-RESOLVED INVESTIGATIONS OF FLUX DYNAMICS - COLLECTIVE AND SINGLE VORTEX EFFECTS, Physical review letters, 71(23), 1993, pp. 3854-3857
The dynamics of flux vortices in Pb films has been investigated with s
ingle fluxon resolution. With increasing magnetic field, there is a cr
ossover from a region where single vortex effects dominate to one wher
e vortex motion becomes correlated. We have measured the flux bundle c
orrelation radius directly and tracked single vortices or correlated b
undles as they moved under the action of an applied dc current or in r
esponse to a change in temperature. The signatures of flux flow and fl
ux creep have been identified, enabling us to determine the pinning fo
rce at individual pinning sites.