ANALYSIS OF BILINEAR AND BIQUADRATIC EXCHANGE COUPLING IN FE/AG/FE(001) TRILAYERS

Ferromagnetic resonance (FMR) and surface magneto-optical Kerr effect (SMOKE) studies of the exchange coupling in Fe/Ag/Fe(001) structures are presented. The interfaces in these structures can be improved significantly by growing the first Fe(001) layer at a raised substrate temperature. The exchange couplings in Fe/Ag/Fe trilayers were studied as a function of the interlayer thickness and temperature. The improved interfaces in the Fe/Ag/Fe system revealed new features in the exchange coupling which were absent in samples grown entirely at room temperature. Quantitative data from the FMR and SMOKE measurements are compared. The magnetization loops for Fe/Ag/Fe trilayers can be explained well only by including the simultaneous presence of bilinear and biquadratic exchange coupling. It is shown that the exchange coupling through Ag(001) exhibits long wavelength oscillations.