In situ detection of two ferromagnetic resonance modes in coupled Ni/Cu/Co/Cu(001) trilayer structures - art. no. 094413

Ultrathin Ni acid Co films, separated by Cu spacer layers with thicknesses in the range 4-15 monolayers, are prepared and measured in situ via ferroma gnetic resonance (FMR) between 50 and 400 K. Due to the interlayer exchange coupling two resonance modes are observed, corresponding to in- and out-of -phase precession of the rf magnetizations in the two magnetic layers, i.e. , the acoustic and optic mode. The fields for resonance H-res and the linew idths DeltaH(pp) of the exchange coupled FMR modes are measured as a functi on of temperature. Since all the measurements are performed irt situ, we ca n compare the signal of the first (bottom) magnetic layer before and after the evaporation of the second (topmost) one. For the coupled films we obser ve an increase of DeltaN(pp) compared to the uncoupled case. From the shift of H-res after the deposition of the second layer the sign and relative st rength of the coupling is derived.