Theory of photon assisted tunnelling in superconductors. II

Abstract

For pt. I see ibid., vol. 3, no. 7, 1438 of 1973. The formalism of a previous article (Hasselberg 1973) is used for deriving an expression of the second order tunnelling current density. The standing wave model by Hamilton and Shapiro (1970) is used to make it possible to describe the experiments in a satisfactory way. The effect of gap anisotropy of the films is also studied. By this, otherwise divergent expressions are avoided, and an auxiliary parameter introduced by Takayama (1971) can be estimated.