Anisotropic critical-state model of type-II superconducting slabs

Abstract

We introduce a critical-state model incorporating the anisotropy of flux-line pinning to analyze the critical states developing in an anisotropic biaxial superconducting slab exposed to a uniform perpendicular magnetic field and to two crossed in-plane magnetic fields which are applied successively. The theory is an extension of the anisotropic collective pinning theory developed by Mikitik and Brandt. The anisotropic flux-line pinning enters into the critical states by generating the angular dependence of the critical current density and by deviating the direction of the electric field from the current in the plane perpendicular to the vortex line. We find that an enhanced in-plane anisotropy moderates the gradients of the magnitudes of the magnetic field and the electric field along the slab thickness, however increases the gradients of their rotations.