Thickness dependence of critical current density in YBa2Cu3O7−δfilms with BaZrO3and Y2O3addition

We report the thickness dependence of critical current density ( J c ) in YBa 2 Cu 3 O 7−δ (YBCO) films with 5 mol% BaZrO 3 (BZO) and 5 mol% Y 2 O 3 additions grown on single crystal SrTiO 3 substrates by pulsed laser deposition (PLD). The results show that adding BZO+Y 2 O 3 has reduced the thickness dependence of the self-field critical current density ( J c sf ), compared to that observed in optimized YBCO films, with a significant enhancement of J c sf in the thick film region (>2 µm). The so-called 'dead layer' did not appear until the film thickness was greater than 6.4 µm. We attribute this improvement to the additional pinning centers introduced in the bulk by the addition and a decrease in microstructure degradation with thickness. As a result, J c sf remains as high as 2.3 MA cm −2 in a 6.4 µm thick film. The combination of this high J c sf value and the enhancement of the in-field J c induced by the additions, which was observed in the whole thickness range, leads to a critical current per centimeter width ( I c−w ) in excess of 400 A cm −1 at 1 T and 75.5 K and 530 A cm −1 at 3 T and 65 K under all field directions.