Theory of the Andreev states in a superconducting junction with a ferromagnetic tunnel barrier [S1I(F)S2] in the presence of a Josephson current

The Andreev localized states in superconducting tunnel junctions with a ferromagnetic barrier (S 1 I(F)S 2 ) are analyzed theoretically in the case when a Josephson current is present. It is shown that the energy spectrum of a symmetric SI(F)S junction in its current-conducting state contains two discrete levels corresponding to both projections of a quasiparticle spin. In the absence of a Josephson current, there is a localized state only for one of the spin projections. A number of conditions must be satisfied before localized states can appear in an asymmetric junction