Multilayer YBa2Cu3O7-x/Ca0.3Y0.7Ba2Cu3O7-x Nanocomposite Films With 2-8% BaZrO3 Doping for High-Field Applications

High-field applications require high concentrations of strong pinning centers. In this article, BaZrO3 doped YBa2Cu3O7 (BZO/YBCO) nanocomposite films with BZO doping up to 8 vol.% were fabricated in a multilayer (ML) format by inserting two 10 nm thick Ca0.3Y0.7Ba2Cu3O7-x spacer layers in the BZO/YBCO nanocomposite films for improved pinning and enhanced critical current density J(c) at high fields. Significant J(c) enhancement was observed in all the BZO/YBCO ML films of BZO doping in the entire range of 2-8 vol.% as compared to their SL counterpart's. At 65 K, the enhancement of peak pinning force density (F-p,(max)) is 71, 67, 296, and 47% for 2, 4, 6, and 8 vol.% BZO/YBCO ML films, respectively. In addition, the B-max (the location of the F-p,(max)) is shifted towards higher values for BZO/YBCO ML films by up to 33%. Interestingly, at high BZO doping of 8 vol.%, the enhanced modulated strain field was found to reduce the detrimental effect of Ca ion diffusion on T-c, leading to J(c) enhancement at a strong field up to 9 T at all orientations of the magnetic field.