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 a re presented. The interfaces in these structures can be improved signi ficantly by growing the first Fe(001) layer at a raised substrate temp erature. The exchange couplings in Fe/Ag/Fe trilayers were studied as a function of the interlayer thickness and temperature. The improved i nterfaces in the Fe/Ag/Fe system revealed new features in the exchange coupling which were absent in samples grown entirely at room temperat ure. Quantitative data from the FMR and SMOKE measurements are compare d. The magnetization loops for Fe/Ag/Fe trilayers can be explained wel l only by including the simultaneous presence of bilinear and biquadra tic exchange coupling. It is shown that the exchange coupling through Ag(001) exhibits long wavelength oscillations.