Effect of mixed pinning landscapes produced by 6 MeV Oxygen irradiation on the resulting critical current densities J$_c$ in 1.3 $\mu$m thick GdBa$_2$Cu$_3$O$_{7-d}$ coated conductors grown by co-evaporation

TL;DR

This study investigates how 6 MeV oxygen irradiation creates mixed pinning landscapes in GdBa2Cu3O7-d coated conductors, significantly enhancing critical current densities at high fields while analyzing flux creep behavior and defect effects.

Contribution

It demonstrates that oxygen irradiation introduces mixed pinning landscapes that improve high-field Jc in coated conductors, with detailed analysis of flux creep and defect interactions.

Findings

Irradiation doubles Jc at 5 T for certain doses.

Irradiation suppresses double-kink relaxation peak.

Flux creep rates increase at higher temperatures after irradiation.

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{\deg} (H//45{\deg}) 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{\deg} 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.