GIANT FLUX-CREEP THROUGH THE SURFACE BARRIERS AND THE IRREVERSIBILITYLINE IN HIGH-T-C SUPERCONDUCTORS

Magnetic flux relaxation over the surface barrier in high temperature superconductors ale investigated. Vortex dynamics controlled by the pe netration both of pancake vortices and vortex lines are discussed. The penetration field H-p for pancakes decays exponentially with temperat ure. The size of the magnetization loop is determined by the decay of H-p during the process of relaxation, but its shape remains unchanged. The irreversibility line associated with the pancake penetration is g iven by H-irr proportional to exp(-2T/T-o), and may lie both above and below the melting line.