Enhanced critical current density in melt textured YBCO via Au ion surface irradiation

We irradiated both side of bulk melt textured YBCO with 235 MeV Au ions. The thickness of the specimens is significally larger than the penetration range of the ions so that two surface layers of columnar defects are created. Critical current density enhancements were obtained in temperature and field ranges that are useful for applications. The boundary between reversible and irreversible regime is shifted toward higher temperatures. At higher fields the increase of the relaxation rate with temperature is less steep after irradiation. The general trends are independent of the thickness of the samples, at least in the range from 5% to 13% of volume affected by irradiation.