Correlation between grain and grain-boundary critical current densities in ex situ coated conductors with variable YBa_2Cu_3O_(7-δ) layer thickness

摘要

The dependence of the percolative critical current density at low magnetic fields on YBa_2Cu_3O_(7-δ) (YBCO) layer thickness is studied by comparing grain, J_c~G, and grain-boundary, J_c~(GB), critical current densities for a series of ex situ processed YBCO films on a RABiTS template. Both critical current densities decrease as a function of thickness and the values of J_c~G and J_c~(GB) show a clear correlation which suggests the existence of an interaction between Abrikosov-Josephson vortices on the grain boundaries and Abrikosov vortices in the bulk of the grains. This opens the possibility to improve J_c~(GB) by optimizing the pinning capabilities of the grains.