Theory of the π junctions formed in atomic-scale superconductor/ferromagnet superlattices

Abstract

Using the Green’s-functions method we investigate theoretically a model of atomic-scale superconductor/ferromagnet (S/F) superlattices. In this model the phase of the order parameter changes periodically, and the intrinsic phase difference k in the ground state can be zero or π. Three basic parameters — the transfer integral t between S and F layers, the exchange field h in F, and the pairing constant Λ in S — characterize the system. We find that the critical Josephson current has a nonmonotonic dependence on h, becoming zero at the critical value h=hcrit(T), corresponding to the transition between k=0 and k=π in the ground state. We calculate the densities of states on S and F layers and show that the quasiparticle spectra are strongly influenced by the values of h and t.

Source-reported materials — not catalogue approval

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