Two-Fold Reduction of J_c Anisotropy in FeSe_0.5Te_0.5 Films Using Low-Energy Proton Irradiation

High in-field performance and low anisotropy of critical current density J_c are important for superconducting wires/tapes in rotating machine and magnet applications. Here, we report measurements of angular dependence of critical current density J_c in proton-irradiated FeSe_0.5Te_0.5 (FST) films at magnetic field up to 35 T. We observed two-fold reduction in the J_c anisotropy of FST films at 4.2 K and 15 Tesla magnetic field by irradiation with low-energy (190 keV) proton. In light of recent demonstration of roll-to-roll irradiation process successfully incorporated in the standard 2G HTS long length production wire, low-energy proton irradiation can be a practical solution to enhance the performance of iron-based superconducting wires and tapes, as low-energy ion sources are inexpensive to operate and are readily available commercially.