Exponential reduction in critical current density in Eu1-xCexBa2Cu3O7-δsuperconductors near critical temperature

Abstract

We have studied how the current-voltage (IV) characteristic below the critical temperature gets affected by electron doping in Eu1-xCexBa2Cu3O7-δ (ECBCO) superconducting systems. The critical current density as a function of T has been extracted in the vicinity but below the critical temperature. Variation of the low critical current density with temperature in the limited range of T has been explained by using an exponential dependence on T. Possibility of the Ambegaokar-Baratoff (AB) to Ginzburg-Landau (GL) crossover has been explored. An exponential nature of the variation in all electron doped superconductors with large angular separation between grain boundaries is attributed to the existence of the vortex fluid state in a narrow range of T.