MEASUREMENT OF THE VORTEX PAIR INTERACTION POTENTIAL IN A TYPE-II SUPERCONDUCTOR

We describe the first direct measurement of the pair interaction poten tial for magnetic flux lines in a type-II superconductor. Our approach relies on a quantitative analysis of Lorentz microscope images of vor tices creeping through a superconducting thin film. Time-resolved vort ex distributions imaged in this way reflect both the vortices' mutual interaction and also the influence of random pinning forces. These inf luences are isolated and quantified by adapting results from the theor y of simple liquids.