A Property of Superconducting Metals

Abstract

IN a recent article by Kapitza (Proc. Roy. Soc., A, 123, 342; 1929) it is suggested that (1) superconductivity is a general phenomenon, which can exist in all metals, but (2) is “masked by an additional resistance which does not disappear in most metals at low temperatures”. This additional resistance is supposed to be due to “structural and chemical imperfections of the metal”. Regarding (1), it appears that the superconductors have a peculiar hitherto unnoticed property, which will be presented in more detail below. Because of this, I am inclined to believe that (1) is incorrect (to all practical purposes), and that one could with equal right say that ferromagnetism is capable of existing in all metals, but is masked by other effects in some. As to (2), it would seem that, since the conductivity in the superconducting state is of an entirely different order of magnitude from that of the conductivity of any normal metal, the additional resistance disappears owing to the short-circuiting, by the pure superconductor, of the impurity or structural imperfection. In the system non-superconductor + impurity, the two resistances are not of such greatly different orders of magnitude, and so the impurity may have a quite marked effect on the resistance.