FLUX-PINNING AND CRITICAL CURRENTS IN A DISORDERED GRAIN-BOUNDARY MODEL

The pinning potential and critical currents of a S-S'-S junction with a slab geometry, in the presence of penetration depth fluctuations in S', are evaluated in the London limit. This junction serves as a model for flux pinning grain boundaries. Disorder induced pinning is found to extend into the S domains over a distance comparable to the penetra tion depth. For ''realistic'' parameters, the calculated critical curr ents have a weak dependence on the grain boundary misalignment angle a nd high values. Comparison with relevant data is discussed.