Correlation of transport properties with grain boundary atomic structure in high-{Tc} superconducting films and tapes

The critical current density of high-{Tc} superconducting thin films is found to be sensitive to the presence of flux-pinning defects, and particularly to the existence of grain boundaries which may act either as pinning centers for the vortices or as weak link junctions. Atomic resolution Z-contrast imaging and spatially resolved electron energy loss spectroscopy provide a method to obtain a direct image of the atomic grain boundary structure for correlation with its electronic structure. Using a combination of transport measurements and electron microscopy, the authors have begun to correlate superconducting properties with atomic scale grain boundary structure using YBCO thin films deposited on SrTiO{sub 3} bicrystals and on Ni substrates (RABiTS)