Record-high critical current density in (Ba,Na)Fe2As2 round wire suitable for high-field applications

Abstract

Record-high value of transport critical current density (Jc) of 71 kA/cm2 under a field of 100 kOe is achieved in (Ba,Na)Fe2As2 round wire processed under high pressure. This value is realized in a short piece cut out from the 18 m-long wires used for a small demo coil reported in the previous study. To evaluate the transport Jc precisely, the cross-sectional area of the superconducting core is carefully evaluated by X-ray computed tomography (CT) measurements. The achieved Jc value is ∼30 % larger than the previous largest transport Jc among all iron-based superconductors round wires.