Phase relations in superconductor-normal metal-superconductor tunnel junctions

摘要

The phase difference phi, between the superconducting terminals in superconductor-normal metal-superconductor tunnel junctions (SINIS), incorporates the phase differences chi(1,2) across thin interfaces of constituent SIN junctions and the phase incursion phi between the side faces of the central electrode of length L. It is demonstrated here that chi(1,2) pass through over their proximity-reduced domain twice, there and back, while phi changes over the single period. Two corresponding solutions, that describe the double-valued order-parameter dependence on chi(1,2) jointly form the single-valued dependence on phi, operating in two adjoining regions of phi. The phase incursion phi plays a crucial role in creating such a behavior. The current-phase relation j(phi, L) is composed of the two solutions and, at a fixed small L, is characterized by the phase-dependent effective transmission coefficient.