Magnetic and structural properties of nitrided Fe and FeTi thin films

Bonder, MJ

Abstract

This thesis investigates the magnetic and structural properties of Fe and Fe$STi1s
thin films nitrided using a nitrogen atom source. In this novel technique, the atom source
produces an atomic nitrogen beam for which multilayer samples with bilayers of the form
Fe/FeN or FeTi/FeTiN were synthesized by varying the thickness of the Fe or FeTi
exposed to the nitrogen beam.
The samples studied here are all in the as-deposited state. X-Ray reflectivity
confirms the presence of a multilayer structure showing sharp multilayer peaks indicative
of good quality interfaces. The electron diffraction data shows a variation of nitride phases
as the thickness of the Fe layer was varied. Fe2N was present when the bilayer was 7A
thick. Increasing the bilayer thickness led to a bilayer consisting of two different nitride
phases until the Fe layer was 42A thick and the bilayer consisted of a-Fe and Fe4N.
In contrast, when Ti was present the phase was body centred cubic for all but the
thinnest bilayers considered in this thesis. The grain structure of the two systems was also
quite different. The Fe/FeN grain sizes ranged from 50 to 1000A in diameter as the bilayer
was varied. In the FeTi/FeTiN sample set the grain growth was inhibited with no
noticeable increase with nitriding. Despite these structural differences the magnetic
character of the two series of samples were consistent. The samples ranged from nonferromagnetic
to ferromagnetic with the presence of weak perpendicular anisotropy
occurring as the bilayer thickness increased. As the bilayer thickness was increased there
was an asymptotic approach of the magnetization to the level of the unexposed materials.
The presence of the perpendicular anisotropy was maintained for a larger parameter space.
In both series the anisotropy is attributed to stress induced by the substrate. Nitriding Fe
and FeTi using the aforementioned technique provides a controlled and viable way to alter
the magnetic and structural properties.

Citation

Bonder, M. Magnetic and structural properties of nitrided Fe and FeTi thin films. (Thesis). University of Salford, UK

• Thesis Type: Thesis
• Deposit Date: Jun 16, 2009
• Publicly Available Date: Jun 16, 2009
• Additional Information: Additional Information : PhD supervisor: Professor Phil Grundy
• Award Date: Mar 1, 2001