X-ray magnetic circular dichroism of Gd/Fe multilayers

Gd(t nm)/Fe(t nm) multilayers in the range of 0.25<t<5 were prepared by rf magnetron sputtering. The structural analysis showed that the multilayers have compositional modulation for bilayer periods of Λ⩾1 nm, and have rather uniform alloy structure for Λ=0.5 nm. From an estimation using the X-ray sum rule, rather large Fe and Gd orbital moments of 0.4 and 0.16 μ_B, respectively, were obtained in the multilayer with Λ=1 nm. The quite small Fe spin moment observed in the multilayers for Λ=5.0 and 10.0 nm, together with the structural analysis, suggests the existence of an amorphous Fe layer having a spin glass like magnetic structure, which is known for YFe and LuFe alloys