Excess current in ferromagnet-superconductor structures with fully polarized triplet component

Abstract

We study the I−V characteristics of ST/n/N contacts, where ST is a BCS superconductor S with a built-in exchange field h, n represents a normal metal wire, and N a normal metal reservoir. The superconductor ST is separated from the n wire by a spin filter which allows the passage of electrons with a certain spin direction so that only fully polarized triplet Cooper pairs penetrate into the n wire. We show that both the subgap conductance σsg and the excess current Iexc, which occur in conventional S/n/N contacts due to Andreev reflection (AR), exist also in the considered system. In our case, they are caused by unconventional AR that is not accompanied by spin flip. The excess current Iexc exists only if h exceeds a certain magnitude hc. At h<hc, the excess current is converted into a deficit current Idef. The dependencies of the differential conductance and the current Iexc are presented as a function of voltage and h.

Source-reported materials — not catalogue approval

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