Magnetic field characterization of high T/sub c/ YBCO superconducting weak links

We report measurements of the voltage across a weak link as a function of applied magnetic field. This measurement provides a sensitive probe of the quality of a weak link, as exhibited by the uniformity of the critical current density across it. Much more structure was found in the current density across longer links, and hysteresis due to flux trapping is evident. Deviations from a uniform critical current density were observed even in very short (4 /spl mu/) links.