NMR study of interface structure in epitaxial Co-Cu superlattices

Co spin-echo NMR has been measured in a series of Co-Cu superlattices grown by molecular-beam epitaxy. The results demonstrate the usefulness of NMR as a probe of interface structure in cobalt-based superlattices. The hyperfine satellites uniquely identify interfacial Co atoms with three Cu nearest neighbors, indicating the presence of atomically abrupt interfaces. This is the first NMR observation of Co atoms at interfaces in a superlattice sample. The measurements also confirm that the Co layers have fcc stacking symmetry with an epitaxially induced in-plane lattice expansion.