Scanning-electron-microscope identification of weak links in superconducting thin films.

We have used a pulsed electron beam in a scanning electron microscope to produce highly localized (~1micron) changes in the electrical properties of a heterogeneous thin film of YBa sub 2 Cu sub 3 O sub (7-delta). The predominant effect of the beam is to locally heat the film, producing a measurable shift in the current-voltage characteristic. In particular, we have precisely located the part of the film responsible for a sharp feature in the current-voltage characteristic corresponding to a single Josephson junction. The technique should also be useful more generally in identifying weak links in superconducting thin films.