MAGNETIC-FIELD DEPENDENCE OF THE CRITICAL-CURRENT OF A LAYERED SUPERCONDUCTOR

We have developed a theory of the effect of a pinned ordered lattice of anisotropic vortices on the critical current J(c) of a layered superconductor. The external field H-ext is taken to be such that vortices lie in the plane of the layers. In this case J(c) is determined by the interlayer Josephson coupling and depends on the distribution of the Josephson phase between adjacent superconducting layers. In view of the anisotropic field penetration we find that the usual Fraunhofer oscillations are absent, and that the critical current decreases as 1-root H-ext/H-0, with the magnetic field scale H-0 determined by the anisotropy of the material. Our results provide a possible explanation for some of the interesting transport properties recently observed in high-T-c cuprates.