Tunable resonant properties of perpendicular anisotropy [Co/Pd]/Fe/[Co/Pd] multilayers

We describe the static and dynamic magnetic behaviors of Fe films (thicknesses 2, 4, and 6 nm) sandwiched between Co/Pd multilayers with strong perpendicular magnetic anisotropy. Out-of-plane measurements of both magnetization and ferromagnetic resonance confirm well-defined Fe layer response modified by large perpendicular exchange field arising from the coupling with the Co/Pd. The field/frequency dispersion is linear for all samples with field intercepts increasing with Fe layer thickness. Analysis in terms of shape anisotropy and interfacial exchange model yields a large out-of-plane interfacial coupling of ∼3.0–3.7 erg/cm2 that is mediated by the coupling across thin Pd layers. The value of this interface exchange is also shown to be tunable with interfacial Pd thickness.