An extended critical state model: Asymmetric magnetization loops and field dependence of the critical current of superconductors

Abstract

An extended critical state model has been developed. The model has considered the equilibrium magnetization of a surface layer and the magnetization of the central region of a superconducting sample. The magnetic flux distributions in the sample have been calculated. An analytical dependence of the critical cur� rent density on the magnetic field with different behaviors in strong and weak fields has been proposed. A rela� tion of the asymmetry of the magnetization loops and the critical current density to the sample size has been established. The model is applicable to the parameterization of magnetization loops of singlecrystal and polycrystalline superconductors.