Structural and magnetic properties of Ru/Ni multilayers

Ru/Ni multilayers of different Ni thicknesses have been fabricated using magnetron sputtering. The structure of the multilayers has been determined by grazing incidence x-ray diffraction and x-ray reflectivity and their magnetic properties by magnetization and polarized neutron reflectivity measurements. The presence of Ru leads to the formation of a hexagonal Ni structure within an interfacial layer similar to 1 nm above each Ru layer, while the rest of the Ni layer relaxes to the equilibrium fcc structure. The hcp Ni interfacial layer has a substantially increased cell volume, and is ferromagnetic with an atomic magnetic moment that increases with Ni layer thickness but remains lower than the value predicted from ab initio calculations.