Flux pinning and critical currents at low-angle grain boundaries in high-temperature superconductors

Calculations of the pinning potential at low-angle grain boundaries in high-temperature superconductors are presented which fully incorporate the periodic nature of the low-angle boundary. A nonlocal kernel provides a smooth transition from an Abrikosov vortex far from the boundary to a Josephson vortex near the dislocations. We examine the angular dependence of critical current in the two idealized limits of pure strain and pure band bending. Recent data appear limited by band bending with significant potential for improvement through doping. (C) 2002 American Institute of Physics.