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

Abstract

The loss-less electrical current-carrying capability of type II superconductors, measured by the critical current density Jc, 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 FeSe0.5Te0.5 films by 6 MeV Au-ions irradiations that produce cluster-like defects with sizes of 10–15 nm over the entire film. The pristine FeSe0.5Te0.5 film exhibits a low anisotropy in the angular dependence of Jc. A clear improvement in the Jc is observed upon Au-ion irradiation for all field orientations at 4.2 K. Furthermore, a nearly 70% increase in Jc 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 Tc. 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.