Electrodynamics of hard superconductors in crossed magnetic fields

Abstract

A model systematically accounting for the cutting of Abrikosov flux lines has been developed for the critical state of a hard superconductor in crossed dc and ac magnetic fields. The electrodynamic equations have been derived by minimizing the Gibbs free energy calculated using the proposed two-velocity hydrodynamic model. One velocity describes the motion of the vortex lattice as a whole, and the other describes the relative motion of the two intersecting sublattices. The resulting equations yield as special cases the previously known electrodynamic equations for hard superconductors. The model provides a natural explanation for the suppression of dc magnetization by a transverse ac magnetic field observed in our experiments.