Structural and Magnetic Properties of Helicon-Sputtered Fe/Si Multilayers

Abstract

In Fe/Si multilayers (MLs) prepared by helicon plasma sputtering, we have investigated the structural and magnetic properties as a function of Fe and Si layer thickness systematically. In [Fe 2 nm/ Si 1 nm] 30 and [Fe 3 nm/Si 1 nm] 20 MLs, large lateral Fe grains grow suggesting small atomic intermixing of Fe and Si, and antiferromagnetic coupling between Fe layers occurs, causing a magnetoresistance of about 0.1%. With decreasing the Fe layer thickness and increasing the Si layer thickness, X-ray diffraction patterns indicate peak broadening due to atomic intermixing between Fe and Si layers, and the magnetization curves indicate the change from antiferromagnetic to ferromagnetic coupling between Fe. Furthermore, in this case, the conversion electron Mossbauer spectra show that the hyperfine field decreases due to the solution of Si atoms in the bulk Fe phase. Doublet peaks appear because of the formation of iron silicides which cause the degradation of antiferromagnetic coupling.