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

Abstract

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.