Dynamics of the Meissner effect: how superconductors expel magnetic fields respecting Alfven's theorem

In a perfectly conducting fluid, magnetic field lines move with the fluid (Alfven's theorem). Thus it is natural to expect that the expulsion of magnetic field from the interior of a metal becoming superconducting is associated with expulsion of charge. Surprisingly, this is not part of the conventional understanding of the Meissner effect. We propose a dynamical description of the Meissner effect involving radial outflow of superfluid and backflow of normal fluid in the transition process, that respects Alfven's theorem. The azimuthal Meissner current results from the magnetic Lorentz force acting on the outflowing charge; the backflowing charge transfers its azimuthal momentum to the body as a whole. The driving force for radial outflow is quantum kinetic energy lowering, hence the Meissner effect would not occur in a classical plasma. To satisfy momentum conservation and reversibility it is indispensable that the normal state charge carriers have hole-like character [1]. This physics is described by the alternative theory of hole superconductivity [2] and not by the conventional Bardeen-Cooper-Schrieffer (BCS) theory.

[1] J. E. Hirsch, Annals of Physics 373, 230 (2016); Phys. Rev. B 95, 014503 (2017).

[2] References in https://jorge.physics.ucsd.edu/hole.html.