Voltage controllable superconducting state in the multiterminal superconductor–normal-metal bridge

Abstract

We study voltage controllable superconducting state in a multiterminal bridge composed of the dirty superconductor/pure normal metal (SN) bilayer and pure normal metal. In the proposed system small control current Ictrl flows via normal bridge, creates voltage drop V, and modifies the distribution function of electrons in a connected SN bilayer. In the case of a long normal bridge the voltage-induced nonequilibrium effects could be interpreted in terms of increased local electron temperature. In this limit we experimentally find the large sensitivity of critical current Ic of Cu/MoN/Pt-Cu bridge to Ictrl and relatively large current gain which originate from steep dependence of Ic on temperature and large Ic (comparable with theoretical depairing current of the superconducting bridge). In the short normal bridge deviation from equilibrium cannot be described by a simple increase in local temperature, but we also theoretically find large sensitivity of Ic to control current/voltage. In this limit we predict existence at finite V of the so-called in-plane Fulde-Ferrell state with spontaneous currents in the SN bilayer. We argue that its appearance is connected with voltage-induced paramagnetic response in the N layer.

Source-reported materials — not catalogue approval

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