The critical state in type-II superconductors with cross-flow effects

A.Badia

Department of Condensed Matter Physics, C.P.S., University of Zaragoza,
Maria de Luna 3, E-50.015 Zaragoza, Spain.

In this contribution we will reviev some impact experiments of magnetic hysteresis in type-II superconductors with cross-flow effects. It is shown that critical state pronciples, in the manner introduced by C.P.Bean for parallel vortex lattices, may be used to describe the observed behavior. We shall present a least action principle which allows a variational interpretation of the critical state. The coarse-grained electrodynamic response of the superconductor is solved by minimizing the magnetic field changes, for a current density vector constrained to belong to some bounded set. The selection of this set determines the specific critical state model in use. Recent magnetization experiments of high-temperature superconductors, which have been devised for discriminating if favour of one model or another will be discussed within the framework of our theory.