Abstract
A series of trilayers of sputtered Fe/Si/Fe were grown to study the interface characteristics and magnetic coupling between ferromagnetic Fe layers (30 A thick) for Si spacer thickness (tSi) ranging from 15 A to 40 A. Grazing incidence x-ray diffraction, AFM, resistivity and x-ray photoelectron spectroscopy (XPS) meas-urements 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 con-sist 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 A. 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.
Highlights
With the ever-rising demands on thin film technology, understanding and controlling thin film growth is vital in case of giant magnetoresistive (GMR) sensors
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
We interpret that the peak position shift is caused by the elongation of the (110) interplanar distance ‘d’ due to large internal stress in the Fe layers induced by adjacent Si layers, and their intermixing during deposition causing the formation of iron silicide layer at the interface
Summary
With the ever-rising demands on thin film technology, understanding and controlling thin film growth is vital in case of giant magnetoresistive (GMR) sensors. A spin-dependent Quantum well description of the electronic structure has been proposed [7,8] All of these models share in common the occurrence of a periodic exchange coupling as a result of two intrinsic properties of the spacer materials: the existence and topology of the fermi surface and the discreteness of the layer thickness. A number of experimental works have been done to understand the mechanism of interlayer coupling in this system, the results are controversial and it is not yet well understood how the formation of iron silicide in the spacer layer affects the coupling. In order to understand the mechanism of the coupling in these multilayers, it is of central importance to elucidate the chemical and magnetic properties of the spacer layer.
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