Irradiation temperature dependence of swift heavy ion induced defects in oxide superconductor EuBa2Cu3Oy

Thin films of oxide superconductor EuBa2Cu3Oy have been irradiated with 80-90 MeV I ions at various temperatures (281, 100, 50 and 12 K). To decide the diameter and the inside-resistivity (resistivity inside the columnar defect), the ion-fluence dependence of electrical resistivity was measured in-situ at 100 and 281 K. The irradiation at 281 K results in the production of columnar defects with much higher inside-resistivity and smaller diameter than those produced by irradiation at 100 K. The difference in the defect structure between these two irradiations can be explained as due to the difference in stability of defects primarily produced by electronic excitation. The result of annealing the sample up to room temperature after irradiation at 100 K supports the above explanation. The irradiation at 50 and 12 K, which are below the superconducting transition temperature, Tc, does not show any difference in irradiation effect from the irradiation above Tc. Effects of irradiation at 100 K and subsequent annealing up to room temperature on the Hall coefficient have also been studied