VORTEX-RESOLVED STUDIES OF YBA2CU3O7-DELTA FILMS USING BISMUTH HALL PROBES

We have developed a new technique for studying flux dynamics in high-T (c) films using bismuth Hall probes deposited directly onto the superc onductor surface. Using this approach we demonstrate single fluxon res olution in YBa2Cu3O7-delta thin films with good signal-to-noise ratio. The results of coincidence measurements at adjacent Hall voltage cont acts indicate that flux motion in the films is uncorrelated at 4.2 K c onsistent with a high density of strong pinning centres. We propose th at this new technique could become a very sensitive tool in the challe nge to understand vortex dynamics in high-T(c) superconductors at the microscopic level.