The effects of heavy-ion irradiation on superconductivity in YBa/sub 2/Cu/sub 3/O/sub 7/ epitaxial films

The authors report a comparative study of superconducting behavior of YBa/sub 2/Cu/sub 3/O/sub 7/ epitaxial films irradiated with Ag and Au ions of several hundred megaelectronvolt energy. The irradiation results in columnar defects of average diameter approximately 55 AA and approximately 110 AA for Ag/sup +21/ and Au/sup +24/ ions, respectively. A universal linear scaling is observed between the fractional areal damage vs. the superconducting transition temperature and normal state resistivity. The results also show that in these films, which have intrinsically strong pinning, a marginal enhancement in the critical current density (J/sub c/) occurs when the defect density is >