AFRL - RZ - WP - TP - 2008 - 2231 FLUX PINNING ENHANCEMENT IN YBa 2 Cu 3 O 7 - x FILMS WITH BaSnO 3 NANOPARTICLES ( POSTPRINT )

Nanoparticles of BaSnO3 were incorporated into YBa2Cu3O7−x (YBCO) films on LaAlO3 substrates for magnetic flux pinning enhancements. More than an order of magnitude improvement in the high field magnetization Jc at 6 T at 77 K was observed as compared to regular YBCO films. The irreversibility field (Hirr) was increased to 8.5 T at 77 K and to 13.4 T at 65 K. The in-field transport current measurements confirmed an order of magnitude improvement in high fields. The angular dependence of the Jc data at 1 T showed that Jc H ‖ c is 1.3 times higher than Jc H ‖ ab indicating the presence of c-axis correlated defects. Transmission electron microscopy studies revealed the presence of a large density of uniformly distributed ∼10 nm sized BaSnO3 precipitates and strain fields around them. A dual sector pulsed laser deposition target is used to produce the films, thus eliminating reactions between BaSnO3 and YBCO during the target preparation stage, but may allow the BaSnO3 to react locally and create defects that act as pinning centres. (Some figures in this article are in colour only in the electronic version)