Effect of intrinsic pinning on critical current in cuprate superconductors

Abstract

Experimental and theoretical studies on the physical properties of cuprate superconductors suggest that the structure of the superconductors consists of alternate strongly and weakly superconducting layers. Vortices parallel to the layers are stabilized in the weakly superconducting layers, since the vortex energy is lowest in the layers. Transport current flows mainly in the strongly superconducting layers. The driving force acting on the vortices is therefore much weaker than that expected from a uniform transport current. Because of these effects, the layer structure itself works as a strong pinning centre for the vortices. A simple theoretical model has been used to study how the critical current in the layerred superconductors is enhanced by this intrinsic pinning. The critical current when the vortices penetrate into the layered superconductors by a zigzag path is also discussed.