Magnetic and structural properties of nitrided Fe and FeTi thin films

This thesis investigates the magnetic and structural properties of Fe and Fe$STi1sthin films nitrided using a nitrogen atom source. In this novel technique, the atom sourceproduces an atomic nitrogen beam for which multilayer samples with bilayers of the formFe/FeN or FeTi/FeTiN were synthesized by varying the thickness of the Fe or FeTiexposed to the nitrogen beam.The samples studied here are all in the as-deposited state. X-Ray reflectivityconfirms the presence of a multilayer structure showing sharp multilayer peaks indicativeof good quality interfaces. The electron diffraction data shows a variation of nitride phasesas the thickness of the Fe layer was varied. Fe2N was present when the bilayer was 7Athick. Increasing the bilayer thickness led to a bilayer consisting of two different nitridephases 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 thethinnest bilayers considered in this thesis. The grain structure of the two systems was alsoquite different. The Fe/FeN grain sizes ranged from 50 to 1000A in diameter as the bilayerwas varied. In the FeTi/FeTiN sample set the grain growth was inhibited with nonoticeable increase with nitriding. Despite these structural differences the magneticcharacter of the two series of samples were consistent. The samples ranged from nonferromagneticto ferromagnetic with the presence of weak perpendicular anisotropyoccurring as the bilayer thickness increased. As the bilayer thickness was increased therewas 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 Feand FeTi using the aforementioned technique provides a controlled and viable way to alterthe magnetic and structural properties