Interference phenomena and long-range proximity effect in superconductor/ferromagnet systems

We study the novel interference mechanism of the long-range proximity effect in superconductor/ferromagnet/superconductor (SFS) structures in the ballistic regime. Even a small non-collinear magnetic domain near the center of a ferromagnetic weak link is shown to restore the singlet supercurrent inherent to the normal metal. The underlying physics of the effect is the magnetic scattering of the Cooper pair by the domain, which reverses total momentum of the pair in the ferromagnet and thus compensates the phase gain before and after the spin-flip scattering. The above phenomenon opens a way to easily control the properties of SFS junctions and, inversely, to manipulate the magnetic moment via the Josephson current