We consider a simple model of a multidomain superconductor-ferromagnet-superconductor (SFS) Josephson junction. Sign-alternating magnetization $M$ in domains leads to a spatial modulation of the phase difference $\phi (x)$. Due to this modulation the Josephson critical current $I_{ c}$ may have a different sign depending on the ratio of the magnetic flux in a domain, 4$\pi Ma(2d_{ F}),$ to the magnetic flux quantum. This phase modulation, but not a nonmonotonic dependence of the local critical current density $j_{ c}$, may be the reason for oscillations of the current $I_{ c}$ { \bf \}as a function of the F layer thickness $2d_{ F} $ or temperature, observed in experiments.
Categories: cond-mat.supr-con