The Phenomenological Theory of Superconductors
Emory Cook · Physical Review · 1940
Proceeding from the idea that the superconducting electrons are free, classical particles under the influence solely of the electric field, London found it necessary to make an integration constant vanish arbitrarily in order to obtain agreement with the Meisner effect. A variation principle constructed from the same classical ideas gives the experimental result without resorting to an additional assumption. The very precise, linear approximation results in London's equations; the rigorous theory has the same qualitative character. Unlike Mie's theory, the present theory has a satisfactory gauge invariance.