MeV cluster ion induced defect production in high Tc superconductors

Bi2Sr2Ca1Cu2O8+delta and YBa2Cu3O7-delta thin films were irradiated by 23 MeV C-60 and 24 MeV Au-5 cluster ions from a tandem accelerator. The defect production of the C-60 cluster ions in Bi2Sr2Ca1Cu2O8-delta exceeds that of U-238 ions With an energy of 2.7 GeV. The analysis of the mechanism underlying the defect production leads to different conclusions: (i) for C-60 clusters we find independence of nuclear and electronic contributions to the defect production as in the case of atomic projectiles, (ii) for Au-5 cluster ions this independence has lost it's validity. A possible interpretation of the Au-5 results is that nuclear defects are annealed by the electronic energy loss. The size of the effective damage radii obtained for the Bi2Sr2Ca1Cu2O8+delta, film may indicate that continuous tracks are formed in this film via the C-60 and Au-5 irradiation.