The pinning potential at single flux vortices investigated using sub-micron hall probes

Abstract

We have imaged individual flux vortices in 200nm-thick superconducting Pb films using sub-micron Hall probes with an excellent combination of spatial and temporal resolution. Correlation of signals at separate Hall contacts shows that flux enters the film in correlated bundles of ∼5μm diameter. With an applied supercurrent, we have been able to move individual vortices distances of typically 30–40nm between minima in the pinning potential that differ by ∼0.5eV. We have determined pinning forces as a function of temperature for individual pinning sites. At higher applied fields the intervortex interaction alone is sufficient to move vortices between different potential minima as the temperature approaches T c.