Si L_2,3 emission spectra from the interfaces in antiferromagnetically coupled Fe/Si multilayers

An Fe(3.0 nm)/Si(1.3 nm) multilayer had been found to exhibit a fairly strong antiferromagnetic coupling by Endo et al. However, the medium responsible for the interlayer coupling had not been assigned. We measured the Si L_2,3 emission spectra from Fe(3.0 nm)/Si(t) multilayers of t = 0.5, 1.0, 1.5, 2.0, and 4.0 nm thick. From the emission spectra the interface of the multilayers was found to consist of dominantly Fe₃Si alloy. From a rough spectral analysis, there seems to remain a very thin a-Si and/or high-resistive Fe-Si alloy layer sandwiched between the Fe3Si layers, which is responsible for the strong interlayer coupling.