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 (PIT) method. The relationship between the cold-work deformation process and the superconducting properties of wires were systematically studied. It was found that flat rolling can efficiently increase the density of the superconducting core and largely improve the transport critical current density (Jc) of as-drawn wires. The Jc of the best sample achieved 21.1 kA/cm^2 at 4.2 K in self field, and showed very weak magnetic field dependence in high fields. Our result suggested a promising future of multifilamentary iron-based superconductors in practical application. 
Chao Yao, Yanwei Ma, Chengduo Wang, Xianping Zhang, Dongliang Wang,   Chunlei Wang, He Lin, Qianjun Zhang
cond-mat.supr-con