Thermodynamic Properties of Josephson Junction with a Normal Metal Barrier

Abstract

There has been considerable interest in the theoretical investigation of a pure SNS contact,^l–4 since it provides another good model, besides the simple tunnel junction, on which weak superconductive phenomena (Josephson phenomena) can be studied microscopically. Detailed descriptions of the model are given elsewhere.² We regard the SNS system as an inhomogeneous superconductor with a square-well configuration of the order parameter, and consider the Green’s function describing the propagation of an electron over the whole system, including the transfer processes across the barrier. This kind of Green’s function may well be defined even if the system is carrying a zero-voltage current. In this case the system is regarded as in a thermodynamically metastable state and the current (whose effect is represented in terms of the phase difference ø of the order parameter across the barrier) plays the role of a thermodynamic variable.