Critical current in S-FNF-S Josephson structures with the noncollinear magnetization vectors of ferromagnetic films

Abstract

The critical current I C of S-FNF-S Josephson junctions, which are ferromagnet (F)-normal metal (N)-ferromagnet multilayer structures whose ends are in contact with the superconducting (S) electrodes, has been calculated. It has been shown that both the magnitude and sign of I C depends significantly on the misorientation angle α of the magnetization vectors M 1, 2 of the ferromagnetic films and the distance L between the superconducting electrodes. The effect of the triplet superconducting component ∼〈ψ↑ψ↑〉 ∼〈ψ↓ψ↓〉 appearing in the structure on I C(α) has been analyzed. It has been proven that a new type of the π junction exists, appearing due to the superposition of two contributions to I C that decrease monotonically with L and are damped at lengths about the coherence length of the normal metal. It has been shown that the effective control over the magnitude and sign of I C of the structure is achieved at a small deflection of the vectors M 1, 2 from the antiferromagnetic (M 1 ↑↓ M 2) configuration.