IRRADIATION-INDUCED PINNING IN SINGLE-CRYSTAL AND THIN-FILM TL2CA2BA2CU3OY SUPERCONDUCTORS

Magnetization relaxation measurements were used to directly measure the effects of ion irradiation on magnetic flux pinning. The pinning potential U in a Tl2Ca2Ba2Cu3O(y) single crystal irradiated with 4.5 MeV protons, to a damage level of 4 x 10(-4) dpa, increased by almost-equal-to 25% at 25 K. In contrast, U for a highly oriented polycrystalline (pc) thin film irradiated with 300 keV He ions to a damage level of 2 x 10(-4) dpa increased by only 5% at 25 K (and less at higher temperatures). Enhancement of the magnetization critical current density J(cm) is determined as a function of temperature and damage in the single crystal and pc thin film. High-energy proton irradiation increased J(cm) in the single crystal by an order of magnitude at 25 K but had only a small effect on J(cm) in the pc thin film.