Measurement of the Vortex Pair Interaction Potential in a Type-II Superconductor

We describe the first direct measurement of the pair interaction potential for magnetic flux lines in a type-II superconductor. Our approach relies on a quantitative analysis of Lorentz microscope images of vortices creeping through a superconducting thin film. Time-resolved vortex distributions imaged in this way reflect both the vortices{close_quote} mutual interaction and also the influence of random pinning forces. These influences are isolated and quantified by adapting results from the theory of simple liquids. {copyright} {ital 1998} {ital The American Physical Society}