Strongly enhanced flux pinning in one-step deposition of BaFe2(As0.66P0.33)2 superconductor films with uniformly dispersed BaZrO3 nanoparticles

The high upper critical field and low anisotropy of the iron-based superconductor BaFe2As2 make it promising for its use in the construction of superconducting magnets. However, its critical current density in high magnetic fields needs to be improved. Here we demonstrate a simple, one-step and industrially scalable means of achieving just this. We show that introducing controlled amounts of uniformly dispersed BaZrO3 nanoparticles into carrier-doped BaFe2As2 significantly improves its superconducting performance without degrading its structural or superconducting properties. Our BaFe2(As0.66P0.33)2 films also exhibit an increase in both the irreversibility line and critical current density at all magnetic-field orientations. These films exhibit nearly isotropic critical current densities in excess of 1.5 MA cm−2 at 15 K and 1 T—seven times higher than previously reported for BaFe2As2 films. The vortex-pinning force in these films reaches ~59 GN m−3 at 5 K and 3–9 T, substantially higher than that of the conventional Nb3Sn wire. Iron-based superconductors are promising for its use in building superconducting magnets; however, their high-field critical current density needs to be improved. Miura et al. show that this can be achieved with a one-step growth process that uniformly incorporates BaZrO3 nanoparticles into BaFe2As2films.