SURFACE EFFECT ON THE MAGNETIC-RELAXATION IN HIGH-TEMPERATURE SUPERCONDUCTORS

The magnetic relaxation and creep of the Abrikosov vortices in high-te mperature superconductors are strongly affected by surface barriers, w hich can dominate over the bulk pinning, especially near T(c). This re sults in a strong difference of the relaxation rates for vortex entry and exit, non-logarithmic time dependence of the magnetic moment and o ther peculiarities. An competitive interplay between the surface and b ulk relaxations, which gives rise to a crossover in the M(ln t) depend ence, is discussed.