Abstract

We report the influence of crystalline defects introduced by 6 MeV O-16(3+) irradiation on the critical current densities J(c) and flux creep rates in 1.3 mu m thick GdBa2Cu3O7-delta coated conductor produced by coevaporation. Pristine films with pinning produced mainly by random nanoparticles with diameter close to 50 nm were irradiated with doses between 2 x10(13) cm(-2) and 4 x10(14) cm(-2). The irradiations were performed with the ion beam perpendicular to the surface of the samples. The J(c) and the flux creep rates were analyzed for two magnetic field configurations: magnetic field applied parallel (H parallel to c) and at 45 degrees (H parallel to 45 degrees) to the c-axis. The results show that at temperatures below 40 K the in-field J(c) dependences can be significantly improved by irradiation. For doses of 1 x10(14) cm(-2) the J(c) values at mu H-0 = 5 T are doubled without affecting significantly the J(c) at small fields. Analyzing the flux creep rates as function of the temperature in both magnetic field configurations, it can be observed that the irradiation suppresses the peak associated with double-kink relaxation and increases the flux creep rates at intermediate and high temperatures. Under 0.5 T, the flux relaxation for H parallel to c and H parallel to 5 degrees in pristine films presents characteristic glassy exponents mu = 1.63 and mu = 1.45, respectively. For samples irradiated with 1 x 10(14) cm(-2), these values drop to mu = 1.45 and mu = 1.24, respectively (C) 2017 Elsevier B.V. All rights reserved.