Strongly enhanced current densities in Sr0.6K0.4Fe2As2 superconducting tapes

Improving transport current has been the primary issue for practical application of superconducting wires and tapes. However, the porous nature of powder-in-tube (PIT) processed iron-based superconducting tapes is thought to be one of the important reasons for the low Jc values. In this work, the superconducting core density of ex-situ Sr0.6K0.4Fe2As2 tapes was significantly improved by employing a simple hot pressing as an alternative route for final sintering. At 4.2 K, the transport Jc values showed excellent values of 5.1x10^4 A/cm^2 at 10 T and 4.3x10^4 A/cm^2 at 14 T, respectively, which attain the Jc level desired for practical applications. Moreover, the Jc values exhibited extremely weak magnetic field dependence. These results clearly demonstrate that PIT pnictide wire conductors are very promising for high field magnet applications.