Flux pinning in ternary (Nd-Eu-Gd)Ba2Cu3O7-delta: Optimization for the highest pinning

The optimization of high-quality melt-processed ternary (Nd-Eu-Gd)Ba2Cu3O7- delta composite samples has been carried out to achieve the largest pinning . Our results suggest that the interaction between the twin planes and the fine second-phase precipitate forms a strongly pinned entangled vortex liqu id in which vortices are correlated along the c axis. This pinned vortex li quid freezes into a glassy state at low temperature rendering high critical current density, J(c). The maximum J(c) can be achieved in as-grown optima lly annealed twinned sample with second phase precipitate without disturbin g the twin influence. (C) 2000 American Institute of Physics. [S0003-6951(0 0)03639-1].