Current-voltage characteristics of the double tunnel junctions Co2CrAl–I–Pb/Sn–I–Pb under spin-polarized tunnel injection

Current-voltage characteristics and existence features of a superconducting state under the action of tunneling injection of the spin-polarized current Iinj with a high spin polarization degree (p ≈ 0.97) were studied in double tunneling junctions ferromagnet-insulator-superconductor-insulator-superconductor Co2CrAl–I–Pb/Sn–I–Pb. An empirical formula was proposed for describing a dependence of the energy gap Δ on Iinj. A new spin-polarized inhomogeneous superconducting state consisting of superconducting and resistive regions was found. An existence of the proximity effect through a tunnel barrier between ferromagnetic and superconducting films was established. An effective recombination time of spin-polarized quasiparticles in the nonequilibrium superconductor Pb was estimated.