Surface antiferromagnetic coupling of Fe/Cu(001) induced by NO adsorpion studied by means of depth-resolved XMCD method

Effects of NO adsorption on the magnetism of Fe(2 and 4 ML)/Cu(001) films have been studied. XMCD spectra have been measured for the films before and after NO adsorption. The bare 4 ML Fe film is magnetized perpendicularly, and m_s^eff is 2.5 μ_B. However, the NO adsorbed 4 ML Fe film exhibits in-plane magnetization and shows m_s^eff of 1.2 μ_B, which is about a half of m_s^eff of the bare film. The apparent fifty percent reduction of m_s^eff can be attributed to an idea that m_s^eff of 1 ML aligns in the opposite direction to that of the other 3 MLs'. This antiferromagnetic coupling between the topmost layer and the other layers is suggested by the careful analyses of the depth resolved XMCD spectra.