The interest to the charge imbalance phenomena [1,2] has grown recently in connection with planar nanosystem investigations since nonequilibrium quasiparticles appear in mesoscopic superconducting (S) structures due to narrowings, interfaces with submicron normal metal parts (N) etc., even at T<<Tc [3]. We have investigated the quasiparticle transport in planar submicron superconductor/normal metal (S/N) structures with SNS Josephson junctions (Nb-Cu-Nb, Nb-Au-Nb) and normal metal (Cu, Au) N-injectors. A nonlocal supercurrent was observed in Josephson junctions, when nonequilibrium  quasiparticles were injected from a normal-metal electrode into one of the superconducting banks of the Josephson junction in the absence of a net transport current through the junction. The occurrence of the nonlocal supercurrent in the junction is related to the need to compensate the quasiparticle flow in it. The charge-imbalance relaxation length in niobium was determined experimentally by using the nonlocal measurement scheme proposed in [3]. Along with aluminum, niobium is the most widely used superconductor for fabrication of superconducting electronic nanodevices, detectors, bolometers.

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      [3] T. E. Golikova, M. J. Wolf, D. Beckmann, I. E. Batov, I. V. Bobkova, A. M. Bobkov, and V. V. Ryazanov, Phys. Rev. B 89 104507 (2014)

I.S. Lakunov, S.V. Egorov, E.D. Mukhanova, I.E. Batov, T.E. Golikova, V.V. Ryazanov
JETP Letters 118, issue 9 (2023)