Enhanced critical current in superconducting FeSe0.5Te0.5films at all magnetic field orientations by scalable gold ion irradiation

The loss-less electrical current-carrying capability of type II superconductors, measured by the critical current density J_c, can be increased by engineering desirable defects in superconductors to pin the magnetic vortices. Here, we demonstrate that such desirable defects can be created in superconducting FeSe_0.5Te_0.5 films by 6 MeV Au-ions irradiations that produce cluster-like defects with sizes of 10–15 nm over the entire film. The pristine FeSe_0.5Te_0.5 film exhibits a low anisotropy in the angular dependence of J_c. A clear improvement in the J_c is observed upon Au-ion irradiation for all field orientations at 4.2 K. Furthermore, a nearly 70% increase in J_c is observed at a magnetic field of 9 T applied parallel to the crystallographic c-axis at 10 K with little reduction of the superconducting transition temperature T_c. Our studies show that a dose of 1×10¹² Au cm^–2 irradiation at a few MeV is sufficient in order to provide a strong isotropic pinning defect landscape in iron-based superconducting films.