In-field dependences of the critical current density J${}_c$ in GdBa${}_2$Cu${}_3$O${}_{7-d}$ coated conductors produced by Zr irradiation and post-annealing at low temperatures

Abstract

We report the influence of 6 MeV Zr${}^{4+}$ irradiation and post-irradiation annealing (200 °C) in the in-field dependences of the critical current densities J${}_c$ of 1.3 $\mu$m thick GdBa${}_2$Cu${}_3$O${}_{7-d}$ coated conductors grown by co-evaporation. Samples were irradiated with 6 MeV Zr${}^{4+}$ and fluences between 2.3x10${}^{11}$ cm${}^{-2}$ and 3x10${}^{12}$ cm${}^{-2}$. The correlation between the superconducting critical temperature T${}_c$ and in-field dependences of critical current densities J${}_c$ has been analyzed. In addition, random disorder introduced by irradiation was reduced by thermal annealed at 200 °C. The analysis of our experimental findings indicates that the optimal irradiation (reducing random disorder by annealing) results in the suppression of the self-field J${}_c$ of $\simeq$ 10 $\%$ and in-field J${}_c$ enhancements nearly doubled at about 5 T. A clear correlation between T${}_c$, disorder and self-field J${}_c$ is observed. Additional random disorder and nanoclusters suppress systematically T${}_c$ and increase the flux creep relaxation at intermediate temperatures (reducing the characteristic glassy $\mu$ value).

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