Enhanced high-field performance in PLD films fabricated by ablation of YSZ-added YBa₂Cu₃O_7-x target

YBa₂Cu₃O_7-x+Y₂O ₃-stabilized ZrO₂ (YBCO+YSZ) mixed films were prepared on SrTiO₃/MgO substrates by pulsed-laser deposition from a YBCO target with a thin YSZ sector on top. The J_c at 77K for the mixed YBCO+YSZ thin film was enhanced. The J_c at 77K for the pure film and the mixed YBCO+YSZ thin film were 1.46 and 1.95MAcm^-2 (self field) (and 0.09 and 0.28MAcm^-2 (, B ≤ 5T)), respectively, even when both films were prepared using the same deposition conditions. The maximum pinning force of a doped film (77K, ) was 15.9GNm^-3, which is comparable to the value reached by NbTi at 4.2K. In the YSZ-added sample, the angular dependence of J_c showed a broad peak at due to the flux pinning by the c-axis correlated defects. Elongated nanorods grown parallel to the c axis were consistently observed in the cross-sectional TEM images.