Experimental Evidence of Dipolar Interaction in Bilayer Nanocomposite Magnets
MARYLAND UNIV COLLEGE PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
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We use magnetic thin film hardnonsoft-magnetic trilayer systems to probe the nature of the hardsoft phase interaction and the role played by dipolar fields in onedimensional d magnetic systems. We have systematically investigated six wedge samples where the thickness of a Cu spacer layer tCu was gradually changed to create a varying interfacial effect on the interaction between a CoPt hard layer and a Fe soft layer. Magneto-optical Kerr effect was used to obtain the magnetization loops at 28 points on each sample, and the nucleation field HN as a function of tCu was employed to characterize the layer interaction as a function of tCu. HNtCu show a RKKY oscillatory behavior in addition to a non-negligible dipolar contribution, which had an exponential dependence. The dipolar term, which cannot be always neglected, is affected by the interface roughness and also by the CoPt crystallinity. Therefore, we cannot always consider exchange coupling to be the dominant interaction in one-d hardsoft magnetic bilayer systems, particularly during magnetic reversal.
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