Influence of random point defects introduced by proton irradiation on the flux creep rates and magnetic field dependence of the critical current density Jc of co-evaporated GdBa2Cu3O7-δ coated conductors

We report the influence of random point defects introduced by 3 MeV proton irradiation (doses of 0.5 x 10(16), 1 x 10(16), 2 x 10(16) and 6 x 10(16) cm(-2)) on the vortex dynamics of co-evaporated 1.3 mu m thick, GdBa2Cu3O7-delta coated conductors. Our results indicate that the inclusion of additional random point defects reduces the low field and enhances the in-field critical current densities J(c). The main in-field J(c) enhancement takes place below 40 K, which is in agreement with the expectations for pinning by random point defects. In addition, our data show a slight though clear increase in flux creep rates as a function of irradiation fluence. Maley analysis indicates that this increment can be associated with a reduction in the exponent mu characterizing the glassy behavior.