Substrate decoration for improvement of current-carrying capabilities of YBa₂Cu₃O_x thin films

The effects of substrate decoration with yttria and Y:ZrO2 on the structural and electrical properties of the YBa2Cu3Ox (YBCO) thin films are studied. The films were deposited on (LaAlO3)3–(Sr2AlTaO8)7 substrates by pulsed laser deposition. Two different structures of decoration layer were applied, a template layer of nanoparticles and an uniform ultra-thin layer. Significant improvement of current-carrying capabilities was observed, especially at high external magnetic fields. Structural studies of these films reveal the presence of extended linear defects in the YBCO matrix. The formation of these structures is attributed to seeding of randomly oriented YBCO grains due to suppression of epitaxy in the very beginning of the deposition. The films of both kinds of decoration layers show nearly the same improvement of jC over the reference film at 77 and 50K: jC (5T and 50K) reaches 0.92 and 0.97MA/cm2 for uniform and template decoration layers. At 5 and 20K the effect of template decoration layers is more beneficial: jC (5T and 20K) values are 3.5 and 4.1MA/cm2, jC (5T and 5K) values are 6.4 and 7.9MA/cm2, for uniform and template decoration layers, respectively.