Strong pinning in melt-textured YBa2Cu3O7-delta with non superconducting Y2BaCuO5 inclusions.

Abstract

We report on a detailed study of the temperature and field dependence of the critical current density J(C) (T, H) in the temperature range 5 K - 100 K and fields up to 50 tesla, in high quality melt-textured YBa2Cu3O7 with 20wt% Y2BaCuO5, fabricated by Directional Solidification. From magnetic measurements, J(C) was determined as approximate to 10(6) A/cm(2) at H = 1 tesla and T = 5 K. From the normalised relaxation rate S (T, H) and the pinning potential U (J, H), determined from detailed SQUID measurements, different pinning regimes have been identified, in accordance with 3D collective pinning theory. The kink on U (J, H) and S (T, H) can be described as a transition from a small bundle to a big bundle collective pinning regime. Furthermore, the J(C) (T, H) dependence has been investigated using high pulsed magnetic fields of up to 50 Tesla The estimated irreversibility fields show the potential of these materials for high field applications