Multilayer YBa ₂Cu ₃O _7-x/Ca _0.3Y _0.7Ba ₂Cu ₃O _7-xNanocomposite Films With 2-8% BaZrO ₃Doping 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 Jc at high fields. Significant Jc 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 (Fp,max) is 71, 67, 296, and 47% for 2, 4, 6, and 8 vol.% BZO/YBCO ML films, respectively. In addition, the Bmax (the location of the Fp,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 Tc, leading to Jc enhancement at a strong field up to 9 T at all orientations of the magnetic field.