Magnetization curves and ac susceptibilities in type-II superconductors: geometry-independent similarity and effect of irreversibility mechanisms

A combined influence of the surface/edge barrier and bulk pinning on the magnetization curves and field-dependent ac susceptibility in type-II superconductors of different geometries and orientation with respect to external field is studied. An universal, geometry-independent behaviour is revealed of the magnetization curves M(H) land the corresponding susceptibilities), which is shown to be controlled by the specifics of the dominant irreversibility mechanism (vortex depinning, edge/surface barrier). A sign reversal is predicted for the higher harmonics of the ac susceptibillity when the irreversibility mechanism changes from bulk pinning to edge barrier. (C) 2001 Published by Elsevier Science B.V.