Spatial variation of the critical current density in Y₁Ba₂Cu₃O₇ films

The critical current density of single-, bi-, and polycrystalline Y1Ba2Cu3O7 films has been imaged by low Temperature Scanning Electron Microscopy (LTSEM) with a spatial resolution of 1/μ. Our experiments directly show that grain boundaries limit the critical current density in polycrystalline films. Substantial variatoons of the critical current density have also been found in high quality, c-axis oriented epitaxial films, which have critical current densities above 1×106A/cm2 at 77K. © 1989.