NEW CRITICAL-STATE MODEL FOR MAGNETIZATION OF HARD TYPE-II SUPERCONDUCTORS

We propose a critical-state model based on the empirical fact that the critical current density Jc in high-Tc superconductors in some cases is found to decay to an essentially field independent level at large inductions B. The new critical current function, Jc(∥B∥), consists of a constant plus a field dependent term of the Kim model type. Analytical expressions for internal induction profiles and the entire shape of major magnetization loops, as well as the initial branch, are derived for the infinite slab geometry. As an illustration it is shown that the new model gives a precise overall description of a magnetization loop measured for melt processed YBa2Cu3Ox. © 1994 American Institute of Physics.