INTRINSIC PINNING IN CUPRATE SUPERCONDUCTORS

We review our theoretical work on the intrinsic pinning in cuprate sup erconductors. The superconductors are constructed by stacking of stron gly and weakly superconducting layers. The vortices are strongly pinne d in the weakly superconducting layers. Since the transport current fl ows mainly in the strongly superconducting layers, the driving force a cting on the vortices is considerably reduced from that in a uniform c urrent system. These effects combine to yield strong vortex pinning an d 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.