FUNDAMENTALS OF VORTICES IN THE HIGH-TEMPERATURE SUPERCONDUCTORS

Strong anisotropy of the high-temperature superconductors affects their vortex structure and flux pinning. In this paper the structure of vortices in these materials is briefly described using the Lawrence-Doniach model, in which superconducting layers are Josephson-coupled. Close to the transition temperature, the model reduces to the anisotropic Ginzburg-Landau theory, but at low temperatures when the magnetic field is parallel to the layers, the vortices have Josephson cores, rather than Abrikosov cores. At other field angles, vortex lines can be represented as two-dimensional pancake vortices in individual layers, connected by Josephson strings.