Exchange Coupling of Ferromagnetic Films Across Nonmagnetic Interlayers

Exchange coupling between ferromagnetic films across nonmagnetic intermediate layers was studied by means of light scattering from spin waves and microwave absorption. The ferromagnetic films were Ni sub 0.8 Fe sub 0.2 (permalloy) and Fe and Au, Ag, Cu, vanadium, Cr, Pd, Ge, Si, Mn, and Bi were nonmagnetic interlayer materials. As expected, the effective interlayer exchange decreases when the interlayer thickness d sub 0 increases. Minimum thickness d sub 0 where the ferromagnetic films are exchange decoupled range between 10-40 A. These results are compared with the concentration dependence of the magnetic ordering temperature in alloys of Fe and Ni with other elements, taking this as a measure for the strength of the exchange. There is a good correspondence which indicates that the coupling effects in the layered structures and the alloys have the same origin, which is presumably by RKKY interaction. 8 ref.--AA