The dependence of the critical current density upon the orientation of the magnetic field was studied in bicrystalline films. When the field was rotated in the plane of the grain boundary, the critical current density exhibited a maximum, when the orientation of the magnetic field was close to the c-axis, in fields of up to 7T. The same measurements, when performed within the interior of the grains, revealed no maxima. The pinning force at the maximum varied as the square root of the magnetic field strength. This was consistent with vortex-pinning by a dense planar distribution of line pinning-points. It was concluded that these results were a clear demonstration of flux-pinning by dislocations in low-angle grain boundaries.

A.Díaz, L.Mechin, P.Berghuis, J.E.Evetts: Physical Review Letters, 1998, 80[17], 3855-8