Figure 1: SF′FF′S Josephson junction containing a trilayer ferromagnet.
From: Reversible control of spin-polarized supercurrents in ferromagnetic Josephson junctions
(a) At high magnetic fields, the F layers are parallel and the combined F layer thickness is much greater than the coherence length of the singlet Cooper pairs; no supercurrent flows through the structure. (b) At zero or low magnetic fields, the inhomogeneous or non-collinear F′ layers converts the spin-singlet Cooper pairs in S to equal spin-triplet Cooper pairs in F thus allowing a finite triplet supercurrent to flow through the structure.
