On the Problem of the Molecular Theory of Superconductivity

Abstract

The electrodynamics and thermodynamics of the superconducting state entail quite definite consequences with regard to the stability character of the supercurrents. In contrast to a recent attempt of Heisenberg, superconductivity is characterized in the present paper not as a state of electronic lattice order in ordinary space, but rather as a kind of condensed state in momentum space which implies a long-range order of the momentum vector $p=mv+\left(\frac{e}{c}\right)A$ in ordinary space as a consequence of the requirements of quantum kinematics. Indications are that it is most probably the exchange interaction associated with the Coulombian field which is responsible for this condensation in momentum space. Ferromagnetism and superconductivity thus would play the role of two opposite limiting cases of the same effect depending on whether the exchange interaction, competing with the zero-point energy, promotes parallel orientation of the electronic spins or a coordination of the translational momentum in a state of vanishing total spin.