Title: Effect of mixed pinning landscapes produced by 6 MeV Oxygen irradiation on the resulting critical current densities J$_c$ in 1.3 $μ$m thick GdBa$_2$Cu$_3$O$_{7-d}$ coated conductors grown by co-evaporation,
Abstract: We report the influence of crystalline defects introduced by 6 MeV
$^{16}$O$^{3+}$ irradiation on the critical current densities J$_c$ and flux
creep rates in 1.3 $\mu$m thick GdBa$_2$Cu$_3$O$_{7-d}$ coated conductor
produced by co-evaporation. Pristine films with pinning produced mainly by
random nanoparticles with diameter close to 50 nm were irradiated with doses
between 2x10$^{13}$ cm$^{-2}$ and 4x10$^{14}$ cm$^{-2}$. At temperatures below
40 K with the magnetic field applied parallel (H//c) and at 45°
(H//45°) to the c-axis, the in-field J$_c$ dependences can be
significantly improved by irradiation. For doses of 1x10$^{14}$ cm$^{-2}$ the
J$_c$ values at $\mu$$_0$H = 5 T are doubled without affecting significantly
the J$_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//c and H//45° in pristine films presents
characteristic glassy exponents $\mu$ = 1.63 and $\mu$ = 1.45, respectively.
For samples irradiated with 1x10$^{14}$ cm$^{-2}$, these values drop to $\mu$ =
1.45 and $\mu$ =1.24, respectively.