Microscopic Foundations of the Meiss ner Effect - Thermodynamic Aspects

We analyze the Mei\ss ner effect from first principles of quantum mechanics. We show in particular the existence of superconducting states minimizing the magnetic free-energy of BCS-like models and carrying surface currents which annihilate the total magnetic induction inside the bulk in the thermodynamic limit. This study is a step towards a complete explanation of the Mei\ss ner effect from microscopic models. It remains indeed to prove that those states are dynamically stable, i.e., quasi-stationary at low temperatures. Note that our analysis shows that the Mei\ss ner effect is not necessarily related to an effective magnetic susceptibility equal to $-1$.