Magnetoelectric effects in superconductor/ferromagnet bilayers

Abstract

We demonstrate that the hybrid structures consisting of a superconducting layer with an adjacent spin-textured ferromagnet demonstrate the variety of equilibrium magnetoelectric effects originating from coupling between the conduction electron spin and superconducting current. By deriving and solving the generalized Usadel equation, which takes into account the spin-filtering effect, we find that a supercurrent generates spin polarization in the superconducting film which is noncoplanar with the local ferromagnetic moment. The inverse magnetoelectric effect in such structures is shown to result in the spontaneous phase difference across the magnetic topological defects such as a domain wall and helical spin texture. The possibilities to obtain dissipationless spin torques and detect domain-wall motion through the superconducting phase difference are discussed.