Enhancement of Critical Current Densities in (Ba,K)Fe2As2 by 320 MeV Au Irradiation in Single Crystals and by High-Pressure Sintering in Powder-in-Tube Wires

We demonstrate a large enhancement of critical current density ($J_{\text{c}}$) up to $1.0\times 10^{7}$ A/cm 2 at 5 K under self-field in (Ba,K)Fe 2 As 2 single crystals by irradiating 320 MeV Au ions. With the very promising potential of this material in mind, we have fabricated a (Ba,K)Fe 2 As 2 superconducting wire through a powder-in-tube method combined with the hot isostatic pressing technique, whose effectiveness has been proven in industrial Bi2223 tapes. The $J_{\text{c}}$ in the wire at 4.2 K has reached 37 kA/cm 2 under self-field and 3.0 kA/cm 2 at 90 kOe. Magneto-optical imaging of the wire confirmed the large intergranular $J_{\text{c}}$ in the wire core.