Synchrotron radiation and polarized neutron study of the enhancement of orbital magnetic moment of Fe in the epitaxial NiFe/Ru multilayer

Epitaxial Ni80Fe20(5 nm)/Ru(x nm)/Ni80Fe20(5 nm) trilayers with thickness x = 0.5-3.0 were prepared on Al2O3(112¯0) substrate. The structure, magnetic properties and magnetic depth profiles of the epitaxial Ni80Fe20(1 1 1)/Ru(0 0 0 1) multilayers were studied by X-ray diffraction, X-ray magnetic circular dichroism and polarized neutron reflectivity. A strongly enhanced orbital moment of Fe in the permalloy layer was observed at the Ru thickness of the first anti-ferromagnetic coupling, which might be due to an interference between two interfaces. At this Ru thickness, the neutron reflectivity data show a 0.8 nm layer at the interface with the magnetic moment perpendicular to the surface plane, which might be due to the enhanced spin-orbital coupling at interface.