Exact solution for the critical state in thin superconductor strips with field-dependent or anisotropic pinning

An exact analytical solution is given for the critical state problem in lon g thin type-Il superconductor strips in a perpendicular magnetic field for the case when the critical current density j(c)(B) depends on the local ind uction B according to a simple three-parameter model. This model describes both isotropic superconductors with this j(c)(B) dependence, but also super conductors with anisotropic pinning with a dependence j(c)(theta) where the ta is the tilt angle of the flux lines away from the normal to the specimen plane.