Magnetic field-controlled −π transitions and their experimental signatures in superconductor-ferromagnet-superconductor junctions

Abstract

Superconductor-ferromagnet-superconductor Josephson junctions are known to exist in the 0 and π states with the transitions between them controlled by the temperature and ferromagnetic interlayer thickness. We demonstrate that these transitions can be controlled also by the external magnetic field directed perpendicular to the layers. By varying the ratio of diffusion coefficients in superconducting and ferromagnetic layers, these field-controlled transitions can be made detectable for arbitrary large values of the exchange energy in the ferromagnet. We also show that the 0−π transitions in the perpendicular field can be observed as the specific features of the flux-flow conductivity dependencies on the ferromagnetic thickness in accordance with recent experimental results.