Beyond Bean’s critical state model: On the origin of paramagnetic Meissner effect

Solving phenomenological macroscopic equations instead of microscopic Ginzburg-Landau equations for superconductors is much easier and can be advantageous in a variety of applications. However, till now, only Beanu0027s critical state model is available for the description of irreversible properties. Here we propose a plausible overall macroscopic model for both reversible and irreversible properties, combining London theory and Beanu0027s model together based on superposition principle. First, a simple case where there is no pinning is discussed, from which a microscopic basis for Beanu0027s model is explored. It is shown that a new concept of u0027flux shareu0027 is needed when the field is increased above the lower critical field. A portion of magnetic flux is completely shielded, named as u0027Meissner shareu0027 and the rest penetrates through vortices, named as u0027vortices shareu0027. We argue that the flux shares are irreversible if there is pinning. It is shown that the irreversible flux shares can be the reason for observed peculiar reversible magnetization behavior near zero field. The overall macroscopic model seems to be valuable for the analysis of fundamental physical properties as well. As an example, it is shown the origin of paramagnetic Meissner effect can be explained by the phenomenological macroscopic model.