Observation of Conduction Electron Spin Polarization Induced in the Ru Layer of the Antiferromagnetically Coupled Co/Ru Multilayer by Resonant X-ray Magnetic Scattering at the Ru K Absorption Edge

Spin polarization of 5p conduction electrons induced in the Ru layers of antiferromagnetically coupled Co/Ru multilayers is investigated by resonant X-ray magnetic scattering at the Ru K absorption edge. Diffraction profiles around (0002) Bragg angles of Co and Ru are measured with linearly polarized synchrotron radiation X-rays of 22.119 keV whose polarization vector is in the scattering plane (p-polarization). The resonant magnetic diffraction profile is extracted by reversing the direction of magnetic field applied perpendicular to the scattering plane. The shape and size of the depth distribution of resonant magnetic scattering amplitude are estimated from the magnetic diffraction profile. It is found that the magnetic scattering amplitude of Ru attenuates within a few atom layers at the interface like Cu-base systems but the average size of the magnetic scattering amplitude is much larger than that of Cu-base systems, suggesting a stronger induced magnetism in the Ru spacer layer.