A PERCOLATION MODEL FOR COPPER-OXIDE SUPERCONDUCTOR NORMAL SUPERCONDUCTOR JUNCTIONS

A percolation model is proposed to explain the anomalous proximity eff ect observed in oxide superconductor-normal-superconductor junctions. Randomly distributed Cooper pair regions are assumed in the two-dimens ional normal-conducting copper oxide. Supercurrent without phase fluct uation is investigated. Our calculation suggests that the decay length is more than about 10 nm and is independent of temperature, which is consistent with experimental results. The normal state which has exper imentally observed localized conduction characteristics can be explain ed by this model. Therefore, the random distribution of Cooper pair re gions seems to explain the transport properties of the normal-conducti ng copper oxide.