Magnetic and Mechanical Properties of Magnetostrictive FeGaSiB Films

Novel magnetostrictive FeGaSiB thin films are of interest for potential applications such as magnetostrictive sensors. The growth parameters of the fabrication method and adding non-magnetic elements such as Ga can influence the structural, magnetic, and mechanical properties of the amorphous FeSiB thin films. This thesis investigates experimentally the effect of the growth parameters and adding Ga into amorphous FeSiB films on these properties. Both the amorphous magnetostrictive FeGaSiB and FeSiB films were fabricated on Si (100) substrates using a co-sputtering and evaporation technique. The differences in the structural, magnetic, and mechanical properties of magnetostrictive FeGaSiB and FeSiB films were investigated and compared. It was found that for all the films, changing the growth parameters and adding Ga did not affect the morphology of the films, as they all had amorphous structures. The magnetic properties and the saturation magnetostriction constants of both the FeGaSiB and FeSiB films were influenced by the film thickness, growth parameters, and the Ga content. It was found that the highest magnetostriction constant of FeGaSiB film was deposited at the lowest Ar gas pressure, pAr, (4 μbar), lowest power PFeSiB, (20W), and Ga rate (0.2 a.u.) for a 50nm thick film. The magnetostrictive FeGaSiB films had mechanical properties lower than the magnetostrictive FeSiB films and for both films, the mechanical properties were influenced by the film thickness and type of substrate.