Anisotropic superconducting critical currents for in situ composites Cu-Nb

Highly oriented Cu-Nb in situ composites have been studied to determine the changes in superconducting critical current which occur as the relative orientation of the magnetic field, transport current, and filament direction are changed. Samples having Cu barrier thicknesses in the range from 5 to 500 nm show J/sub c/ values about a factor of 40 higher for the current parallel to the long axis of the filaments than for the current perpendicular to the long axis. Where the flux line lattice moves perpendicular to the filament direction, the data show that the shear modulus, C66, governs the flux pinning. Where the flux line lattice moves parallel to the long axis of the filaments, the drop in critical current with field is much more rapid