Three-layer systems [ferro-super-ferro (FSF)] with very thin insulating junctions between S and both F layers have been prepared. The superconducting transition temperature $T_{c\uparrow \uparrow }$ (when both F magnetizations are parallel) is lower than $T_{c\uparrow \downarrow }$.

• Received 27 December 1968

DOI:https://doi.org/10.1103/PhysRevLett.22.395