Engineering nanocolumnar defect configurations for optimized vortex pinning in high temperature superconducting nanocomposite wires

We report microstructural design via control of BaZrO(3) (BZO) defect density in high temperature superconducting (HTS) wires based on epitaxial YBa(2)Cu(3)O(7-δ) (YBCO) films to achieve the highest critical current density, J(c), at different fields, H. We find the occurrence of J(c)(H) cross-over between the films with 1–4 vol% BZO, indicating that optimal BZO doping is strongly field-dependent. The matching fields, B(φ), estimated by the number density of BZO nanocolumns are matched to the field ranges for which 1–4 vol% BZO-doped films exhibit the highest J(c)(H). With incorporation of BZO defects with the controlled density, we fabricate 4-μm-thick single layer, YBCO + BZO nanocomposite film having the critical current (I(c)) of ~1000 A cm(−1) at 77 K, self-field and the record minimum I(c), I(c)(min), of 455 A cm(−1) at 65 K and 3 T for all field angles. This I(c)(min) is the largest value ever reported from HTS films fabricated on metallic templates.