Isotropic Pinning Enhancement: Comparison Between Spherical and Point Defects

We have used silver-ion irradiation and proton irradiation to produce point-like and spherical defects in REBa ₂ Cu ₃ O ₇ coated conductors. We compare the resulting pinning landscape for optimized fluences and show that proton irradiation gives a slightly greater pinning enhancement at 20 K, but in the same samples silver irradiation gives significantly better pinning enhancement at 65 K. We attribute this to the relative sizes of the defects and to the distribution of defects resulting from the different ion collision rates.