Imaging local dissipation and magnetic field in YBCO films with artificial defects

We used Low Temperature Laser Scanning Microscopy (LTLSM) to investigate dc current flow in high-J/sub c/ YBCO thin films with artificially prepared defects and correlated the LTLSM response to Magneto Optical Images (MOI). Artificial defects model current blockages such as cracks, high angle grain boundaries or voids. Because the LTLSM voltage response is associated with the local electric field, while MOI shows the local perpendicular magnetic field, the combination of techniques gives complementary local information about the effect of current-limiting defects in superconductors.