Resonant phenomena in multi-barrier superconducting junctions

Abstract

We have numerically obtained the superconducting current through multi-barrier superconducting junctions (MBSJs). Quasiparticles moving in MBSJs have to obey the Bogoliubov–de Gennes equation. The transmission and reflection of quasiparticles are considered in the case of an electron-like quasiparticle coming from the left superconductor, and current–phase relationships are numerically obtained from the probability amplitude of the Andreev reflections from an electron-like to a hole-like quasiparticle in the MBSJ. The period of the current–phase relationship of MBSJ with n barriers is n times longer than that of the ordinary single barrier superconducting junction. There are resonant phenomena in the dependence of the critical current I c on the distance between the left most and the right most barriers D, where each resonance in the I c– D characteristics has ( n−1) peaks, because the MBSJ with n barriers has ( n−1) superconducting cavities between the left most and right most barriers.