Josephson current and $\pi-$state in ferromagnet with embedded superconducting nanoparticles

Abstract

On the basis of Usadel equations we investigate superconductor/ferromagnet/superconductor (S/F/S) hybrid systems which consist of superconducting nanostructures (spheres, rods) embedded in ferromagnetic metal. The oscillations of the critical current of the S/F/S Josephson junctions with the thickness of ferromagnetic spacer between superconducting electrodes are studied. We demonstrate that the $\pi $ state can be realized in such structures despite of a dispersion of the distances between different parts of the electrodes. The transitions between 0 and $\pi $ states at some thickness of ferromagnetic spacer can be triggered by temperature variation.