On the theory of Josephson effect in a diffusive tunnel junction

Specific features of the equilibrium current-carrying state of a Josephson tunnel junction between diffusive superconductors (with the electron mean free path l smaller than the coherence length ξ0) are studied theoretically in the 1D geometry when the current does not spread in the junction banks. It is shown that the concept of “weak link” with the phase jump Φ∼1 of the order parameter exists only for a low transmissivity of the barrier Γ≪l/ξ0≪1. Otherwise, the presence of the tunnel junction virtually does not affect the distributions of the order parameter modulus and phase. It is found that the Josephson current flowing in the vicinity of the tunnel barrier induces localized states of electron excitations, which are a continuous analog of Andreev’s levels in a ballistic junction. The depth of the corresponding “potential well” is much larger than the separation between an Andreev’s level and the continuous energy spectrum boundary for the same transmissivity of the barrier. In contrast to a ballistic...