Topological coupling in magnetic multilayer films

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Abstract
The role of topological coupling, the magnetostatic coupling associated with interfacial roughness in magnetic sandwich/multilayer structures, was studied both analytically and experimentally. We report the first controlled measurements of such topological coupling. A coupling field of the order of 10 Oe between magnetic layers was observed in Co/Cu/Co sandwich structures fabricated with an artificially controlled in‐phase roughness of variable amplitude with a fixed period of 3.5 μm. The coupling field was compared with the value predicted by a first‐order approximation model and correlated with the geometry of the structure. Scale invariance of the coupling field allows the results to be extended to ultrathin giant magnetoresistance/spin valve structures.