Magnetic and structural characterization of high anisotropy cobalt-rich alloys: Thin films and patterns

In this dissertation the structural and magnetic characterization of high anisotropy Co-rich alloys for magnetic recording and MEMS applications has been carried out.; The potential of Co₇₈Sm₂₂ as an ultra-high density recording medium was explored through comprehensive static and dynamic magnetic measurements. It was found out that hard magnetic properties (H_c = 4.5 kOe) can be achieved when CoSm is sputter-deposited on Cr₈₀V ₂₀ underlayer, comparable with those reported for state-of-the-art media at the end of 2002. Furthermore, the chemical stability and reliability of CoSm thin films was studied through combined accelerated aging and electrochemical methods. It was found out that CoSm thin films are more reactive than current recording media (CoPt), and a layer of Si₃N₄ of at least 6 nm provides satisfactory protection.; Electrodeposition of Co₈₀Pt₂₀ onto highly textured Cu seed layer with either {lcub}100{rcub} or {lcub}111{rcub} orientation was studied. The influence of Cu texture and plating current density (cd) on the growth, morphology, microstructure, and magnetic properties of the CoPt films was investigated. Epitaxial CoPt thin films with uniform composition across the film thickness were deposited. The microstructure consists in fcc matrix and hcp matrix when plated on Cu(100) and Cu(111), respectively. CoPt hcp single phase films with c-axis normal to the substrate were grown on Cu(111) when plated at cd = 50 mA/cm2. As opposed to the films plated on Cu(100) which show a mostly in-plane magnetic anisotropy, the films plated on Cu(111) develop a well defined perpendicular magnetic anisotropy (PMA) due to the hcp phase with the c-axis normal to the substrate, which yields coercivities as high as 6.1 kOe. The origin of the high PMA was found to lie in the magnetocrystalline anisotropy.; CoPt micromagnets have been successfully fabricated by the electrodeposition-through-mask method, which despite the small aspect ratio show a definite PMA. The PMA, together with the hard magnetic properties measured (H_c = 4.7 kOe) demonstrate a strong potential for the utilization of these materials in the MEMS area.