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

We analyze the measured critical current Iₘ 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 Icsinφ, but also a phase-coherent part Isgcosφ of the subgap current. The current Iₘ is determined by both components Ic and Isg, and depends in a nonmonotonic way on the voltage V between superconductors and normal reservoirs reaching a maximum at VΔ/e. The obtained theoretical results are in qualitative agreement with recent experimental data.