Epitaxial growth of multilayered YBa/sub 2/Cu/sub 3/O/sub 7-(delta)/Y/sub 0.7/Ca/sub 0.3/Ba/sub 2/Cu/sub 3/O/sub 7-(delta)/ films for high current application

Multilayered YBa/sub 2/Cu/sub 3/O/sub 7-(delta)/ (YBCO)/Y/sub 0.7/Ca/sub 0.3/Ba/sub 2/Cu/sub 3/O/sub 7(delta)/ (YCBCO) films were epitaxially grown on [001] LaAlO/sub 3/ and [001] SrTiO/sub 3/ by using pulsed laser ablation. Constant-high critical current density (J/sub c/) of 106 A/cm/sup 2/ at 77 K has been achieved with the combination of multilayered YBCO and YCBCO layers for films with various thickness. The critical current density exhibits a high constant value for the multilayered structures indicating that the J/sub c/ in the superconductor films no longer decreases with the increase of the film thickness. The result verifies the model that interfaces can limit the density of dislocations that form in the film during the film growth. The artificial multilayered structures terminate the dislocations and the superconductive films at the optimal J/sub c/ conditions maintain a constant high J/sub c/ at various film thickness.