High current densities in superconducting films from magnetization

An experimental study indicates that epitaxial thin films of YBa/sub 2/Cu/sub 3/O/sub 7-x/ made by laser ablation have the CuO planes parallel to the film surface. In the CuO plane critical currents of J/sub c/ approximately=40*10/sup 6/ A/cm/sup 2/ were found at 5 K in zero field. Multilayered films with Gd replacing Y, each 0.01 mu m in thickness, have a J/sub c/ nearly equal to 140*10/sup 6/ A/cm/sup 2/. This higher value is perhaps due to additional point defects. Perpendicular to the CuO planes, Magnetization studies indicate strong pinning effects attributed to the CuO planes acting as barriers to flux motion.<>