Effective Low-Temperature Flux Pinning by Au Ion Irradiation in HTS Coated Conductors

We report the effects of heavy-ion irradiation on critical currents in (Y,Dy)Ba₂Cu₃O_7-δ coated conductors made by a commercial metal organic deposition process. Irradiation with 185 MeV Au ions is investigated and contrasted with previous results on 74 MeV Ag ions. The change in critical current (I_c) is reported as a function of temperature (30-77 K), magnetic field (0-7 T) and magnetic-field angle (full angle dependence). Significant improvements are seen particularly at 30-40 K where I_c can be enhanced over a wide angular range and the minimum of I_c(θ) has been enhanced by up to 60%. This contrasts with the data for the commonly utilized regime of 77 K, 1 T where the I_c enhancements are small or limited to a narrow angular range. This data also serves to illustrate the need to measure Ic in all of the temperature and field regimes of technical interest and to measure the complete field-angular dependence I_c(θ).