1. Definitions and general constants

Superconducting state [1] : state of matter in which, below a certain applied temperature and magnetic field :

• electrical resistivity is zero;

• a strongly diamagnetic effect appears.

Type I superconductors exhibit a perfect diamagnetic state that completely excludes the magnetic field. Under certain conditions, a type II superconductor presents a so-called mixed state, in which the diamagnetic state is imperfect.

Critical temperature T _c . Isotope effect: phase transition temperature between the superconducting and normal states. For a given element, T _c...