Magnetic Interaction between Adsorbed NO andfccCo(001) Thin Films Studied by X-ray Magnetic Circular Dichroism

N K -, O K - and Co L III,II -edge X-ray magnetic circular dichroism (XMCD) was investigated for NO adsorbed on ultrathin fcc -Co(001) films which show both in-planar and perpendicular magnetic anisotropies. Large suppression of spin and orbital magnetic moments of Co was observed upon NO adsorption. Both N and O K -edge XMCD spectra show negative signs at the NO 2π * resonance, irrespective of in-plane and perpendicular magnetic anisotropies. This finding implies the parallel alignment of the NO 2π * orbital magnetic moments with the total magnetization. The results are comparatively discussed with the previous works on CO on Co and Ni films and are interpreted by a simple chemical bonding scheme.