Structure of Co layers in Co/Cu multilayers at the first antiferromagnetic maximum studied by nuclear magnetic resonance

Using Co59 nuclear magnetic resonance, a structural study has been performed on a series of Co/Cu multilayers with Cu thickness of 9 Å (corresponding to the first maximum of antiferromagnetic coupling) and Co thickness varying between 10 and 50 Å. The structure of the Co layer is fcc for small Co thicknesses. With increasing Co thickness, a rapid increase of hcp Co content is observed, particularly for samples between 10 and 30 Å Co. The equivalent thickness of the deposited Co involved in the mixed interface planes is estimated to be a total of about 5 Å for both interfaces of the Co layer. The interface maintains a relatively sharp concentration profile similar to that observed in samples at the second maximum of antiferromagnetic coupling. However, a certain degree of topological disorder in the interface is introduced by the onset of hcp stacking.