Nonsinusoidal current–phase relation in SFS Josephson junctions

Various types of the current–phase relation $I(\varphi)$ in superconductor–ferromagnet–superconductor (SFS) point contacts and planar double-barrier junctions are studied within the quasiclassical theory in the limit of thin diffusive ferromagnetic interlayers. The physical mechanisms leading to highly nontrivial $I(\varphi)$ dependence are identified by studying the spectral supercurrent density. These mechanisms are also responsible for the $0$–$\pi$ transition in SFS Josephson junctions.