Local resistivity as an evaluation tool for thickness dependence of critical current density in YBa₂Cu₃O_7-x coated conductors

We report depth profiling of the critical current density and resistivity of YBa₂Cu₃O_7-x films grown by in situ electron beam evaporation. The method is capable of providing important information on the uniformity of the films, and on the commonly observed property that the critical currents in high temperature superconductor coated conductors do not scale linearly with thickness. Local critical current density shows a clear correlation with local resistivity. Homogeneous transport properties with a large critical current density (4-5 MA/cm² at 77 K, 0 T) are observed in top faulted region while it is found that the bottom part carries little supercurrent with a large local resistivity. Therefore, it is possible that thickness dependence of critical current density is closely related with a topological variation of good superconducting paths and/or grains in the thin film bodies. The information derived from it may be useful in the characterization and optimization of superconducting thin films for electrical power and other applications.