Incorporation of double artificial pinning centers in YBa2Cu3O7−dfilms

YBa 2 Cu 3 O 7− x +BaZrO 3 +Y 2 O 3 (YBCO+BaZrO 3 +Y 2 O 3 ) mixed films were prepared on SrTiO 3 /MgO substrates by pulsed-laser deposition, with an YBCO+BaZrO 3 target with a thin Y 2 O 3 sector stuck on the top. The pinning properties for the double-doped YBCO+BaZrO 3 +Y 2 O 3 thin film were enhanced in comparison with those of a pure YBCO sample prepared in the same experimental conditions. The maximum global pinning forces F p for the double-doped sample are 12.8 GN m −3 near 3 T at 77 K, 46.3 GN m −3 near 4 T at 65 K, and 122 GN m −3 near 9 T at 40 K. In the double-doped sample the angular dependence of J c showed a broad peak at , due to the flux pinning by c -axis correlated defects, combined with a plateau, due to the flux pinning by isotropic pinning centers. Both BaZrO 3 nanorods parallel to the c -axis and Y 2 O 3 nanoparticles randomly dispersed inside the YBCO matrix were consistently observed in the cross sectional transmission electron microscopy images.