Intrinsic pinning in cuprate superconductors

We review our theoretical work on the intrinsic pinning in cuprate superconductors. The superconductors are constructed by stacking of strongly and weakly superconducting layers. The vortices are strongly pinned in the weakly superconducting layers. Since the transport current flows mainly in the strongly superconducting layers, the driving force acting on the vortices is considerably reduced from that in a uniform current system. These effects combine to yield strong vortex pinning and to enhance the critical current. Dependence of the critical current on the direction of applied magnetic field is discussed in connection with the vortex structure in the cuprate superconductors.