Fabrication and transport properties of Sr0.6K0.4Fe2As2 multifilamentary superconducting wires

Seven-core Ag/Fe sheathed Sr0.6K0.4Fe2As2 (Sr-122) superconducting wires were produced by the ex situ powder-in-tube method. The relationship between the cold-work deformation process and the superconducting properties of the wires was systematically studied. It was found that flat rolling can efficiently increase the mass density of the superconducting core, thus, significantly improving the transport critical current density (Jc) of the as-drawn wires. The transport Jc of the best sample achieved 21.1 kA/cm2 at 4.2 K in self field, and showed very weak magnetic field dependence at high fields. Our result suggested a promising future of multifilamentary iron-based superconductors in practical applications.