4-fold enhancement in the critical current density of YBa2Cu3O7 films by practical ion irradiation

We report an up-to-4-fold enhancement in the in-magnetic-field critical current density at 77 K of epitaxial YBa2Cu3O7 films on CeO2-buffered SrTiO3 substrates by 3-MeV Au2+ irradiation. This indicates that irradiation using an industrially practical ion beam, which generally has kinetic energy less than 5 MeV, can provide a substantial increase in the in-field current performance of high-temperature superconductor films. Transmission electron microscopy results show that point-like defects smaller than 6 nm in diameter were created in the films by the irradiation.