Control of Y2O3 nanoislands deposition parameters in order to induce defects formation and its influence on the critical current density of YBCO films

We successfully introduced high-density linear defects as artificial pinning centers (APCs) of the quantized vortices into YBCO films, during the film deposition procedure. APCs were introduced perpendicular to the film surface by using the distributed nanosized Y2O3 islands prepared on SrTiO3(1 0 0) substrates. It is possible to induce strong changes on the shape and density of the Y2O3 islands by varying the deposition conditions. The highest Y2O3 islands density, 226/μm2, was obtained with fifteen laser pulses at 800 °C of substrate temperature. Even if only 10% of the induced defects act as effective pinning centers, Jc of YBCO film grown on the Y2O3 nanoislands/SrTiO3 substrate increased to 1.8 × 107 A/cm2 (20 K, B∥c, 0 T), which is 1.5 times higher than that of the pure YBCO film.