X-ray diffraction spectra at small-angle for the same films whose magnetization curves are shown above. Broader peaks show that there is more disorder in layering for the AF-coupled film with t Si = 14Å. Using Equation 1, these data give bilayer periods lambda = 41.82Å for the nominal (Fe30Å/20Å)x50 film and lambda = 38.10Å for the nominal (Fe30Å/Si14Å)x50 film.