Magnetic interaction between adsorbed NO and fcc Co(001) thin films studied by X-ray magnetic circular dichroism

N K-, O K- and Co L-III,L-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 anisotropics. 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 2pi* resonance, irrespective of in-plane and perpendicular magnetic anisotropies. This finding implies the parallel alignment of the NO 2pi* 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.