Suppression and enhancement of the critical current in multiterminal superconductor–normal-metal–superconductor mesoscopic structures

Abstract

We analyze the measured critical current ${I}_{m}$ in a mesoscopic four-terminal superconductor--normal-metal--superconductor (S/N/S) structure. The current through the S/N interface is shown to consist not only of the Josephson component ${I}_{c}\mathrm{sin}\ensuremath{\varphi},$ but also a phase-coherent part ${I}_{\mathrm{sg}}\mathrm{cos}\ensuremath{\varphi}$ of the subgap current. The current ${I}_{m}$ is determined by both components ${I}_{c}$ and ${I}_{\mathrm{sg}},$ and depends in a nonmonotonic way on the voltage V between superconductors and normal reservoirs reaching a maximum at $V\ensuremath{\cong}\ensuremath{\Delta}/e.$ The obtained theoretical results are in qualitative agreement with recent experimental data.