Theory of Superconductivity

Abstract

IT is a controversial question whether the phenomenon of superconductivity is merely a consequence of the quantum theory of interaction among electrons or whether it depends on the specific crystal structures. The first point of view is taken in Heisenberg‘s theory¹. However, it can be shown by general reasoning that if the ionic forces between ions and electrons are disregarded, all states with a total current different from zero will have higher energy than those without. Moreover, there is a strict isomorphic correspondence between all states without current and all states with a given current. Consequently the free energy of the states with a current cannot be the smallest at any temperature. Secondly, Heisenberg‘s theory predicts the existence of superconductivity in all metals, including the alkali metals ; yet so far experimental evidence does not confirm this.