Study of Sputtered Fe/tSi/Fe Trilayer Films: Magnetic and Electronic Properties

A series of trilayers of sputtered Fe/Si/Fe were grown to study the interface characteristics and magnetic coupling between ferromagnetic Fe layers (30 Å thick) for Si spacer thickness (tSi) ranging from 15 Å to 40 Å. Grazing incidence x-ray diffraction, AFM, resistivity and x-ray photoelectron spectroscopy (XPS) measurements show substantial intermixing between the layers during deposition which results in trilayers of complicated structures for different sub-layer thicknesses. A systematic variation in silicide concentration across the interface is observed by XPS measurements. The Fe layers in the trilayers were observed to consist of Fe layers doped with Si, ferromagnetic Fe-Si silicide layers and nonmagnetic Fe-Si silicide interface layer, while the Si spacer was found to be Fe-Si compound layers with an additional amorphous Si (α-Si) sublayer for tSi ≥ 30 Å. A strong anti-ferromagnetic (AF) coupling was observed in trilayers with iron silicide spacers, which disappeared if α-Si layers present in the spacers. The observed magnetization behaviour in each case is interpreted in terms of changes in interfacial structural and electronic properties due to variation in film thickness.