Origin of superconductive glassy state and extrinsic critical currents in high-Tc oxides

The short coherence length of high-Tc oxides is shown to induce considerable weakening of the pair potential at surfaces and interfaces. It is argued that this effect is responsible for the existence of internal Josephson junctions at twin boundaries, which are at the origin of the superconductive glassy state, as well as for gapless tunneling characteristics.