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 Tl2Ca2Ba2Cu3Oy single crystal irradiated with 4.5 MeV protons, to a damage level of 4x10-4 dpa, increased by ≅ 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 2x10-4 dpa increased by only 5% at 25 K (and less at higher temperatures). Enhancement of the magnetization critical current density Jcm is determined as a function of temperature and damage in the single crystal and pc thin film. High-energy proton irradiation increased Jcm in the single crystal by an order of magnitude at 25 K but had only a small effect on Jcm in the pc thin film. (orig.)