Studies Of CoPt Thin Films For Ultra-high Density Perpendicular Magnetic Recording Media

In recent year, much interest has been paid on L1₀ nanocomposite CoPt -based thin films as potential candidate for ultrahigh density recording media due to their larger magnetocrystalline anisotropy, In order to obtain ideal magnetic property of CoPt thin film for ultrahigh-density recording media, the key feature underlying the exceptional magnetic properties of CoPt alloys is the chemically ordered L1₀ phase, which, at the equiatomic composition, is comprised of alternating atomic planes of Co and Pt along the unit-cell c axis.In this article, we have prepared a series of CoPt alloy with different content of Co element and focused on three kinds of additive to improve the magnetic property and microstructure of CoPt alloy thin films. Dependence of composition and post-annealing, and microstructure and magnetic properties of the film with various additives were investigated .the main conclusions are as follows:1. While Co content at 55 at. % ,it is easily to obtain equiatomic CoPt film, with the increase of annealing temperature ,the orderd L1₀ phase were obtained. As for the equiatomic CoPt films, it is believed that highest coercivity arose from the fully chemical ordered L1₀ structure.2. The addition of certain amount of Ag element in CoPt alloy can increases out-plane coercivity of CoPt thin film. The addition 10 at. % Ag element in CoPt alloy ehances the CoPt (001) texture, the films show out-plane easy axis and improve the microsturcture magnetic properties of CoPt alloy thin film. While the content of Ag element over 30 at. %, the CoPt(001) texture are weakened, the (111) peak is strongest peak and the film show in-plane easy axis.3. The addition of SiO₂ in CoPt alloy thin film impede the growth of CoPt grain, the parameter of CoPt grain decreased from 52nm to 12nm. We also found the addition of SiO₂ in CoPt thin film increases the ordered temperature.the fcc-fct transformation does not occur completely at 500℃.4. We dope varies content of Cu element in CoPt alloy thin film, and foundthat the content of Cu element in 5 to 10 at. % will decrease the orderedtemperature. The ordered Llo-CoPt phase are obtained at 400°C by dope10 at.% Cu element in CoPt alloy thin film. With more content of Cuelement in CoPt thin film the coercivity decreased, the films show softmagnetic property while 30 at. % Cu dope in CoPt thin film.At last we successfully prepared Llo phase CoPt thin film by co-sputtering, andobtained (001) oriented texture by dope Ag element, decrease the orderedtemperature by addition of Cu element in CoPt alloy thin film and reduce theparameter of CoPt grain by additive of SiC>2. All of this improves the magneticproperties of CoPt alloy thin films.