Superconducting FSF spin-valves with strong ferromagnetic elements
The theory and transport measurements are presented on superconducting spin-valve systems, where the controlled non-collinear arrangement of two ferromagnetic Co layers can be used to influence the superconducting state of Nb. We observe a very clear oscillation of the superconducting transition temperature (Tc) with the relative orientation of the two ferromagnetic layers. We report the formation of long-range triplet superconducting correlations (LRTC) according to our theory. Singlet BCS correlations is shown to lead to a weak enhancement of Tc for the anti-parallel configuration of exchange fields, while much larger changes are observed for other configurations, which can be attributed to drainage currents due to LRTC formation.