Element specific hysteresis loops of Co and Fe in annealed CoFe/Cu multilayers

Sets of antiferromagnetically aligned [Co₉₀Fe₁₀/Cu]₆ multilayers are grown by magnetron sputtering on buffered Si(001) substrates and are then subjected to ex-situ annealing in a high vacuum furnace for 1 hour at 450°C. The element specific magnetic roughness and hysteresis behaviour corresponding to the ferromagnetic (FM) and antiferromagnetic ordering are obtained as a function of the annealing temperature of the multilayers. The measurements taken at the L₃ resonance show significant differences in the magnetic interface roughness. The intensity of the FM peak at the Co L₃ edge shows the greatest similarity to the bulk [Co₉₀Fe₁₀/Cu]₆ VSM data. However, the Fe data reveals differences in the Fe behaviour compared to the Co in both the approach to saturation and in the switching itself. The post annealed giant magnetoresistance is also studied as a function of the annealing temperature.