Nanoscale investigation of thin film perpendicular magnetic recording media

The HCP CoCrPtO Perpendicular magnetic recording media are attractive to achieve recording densities over 1 Tbit/in2 owing to their low media noise characteristics. Structural refinement is critical to the development of ultra-high recording density perpendicular media with low noise. The grain size and film thickness are on a scale of 8 nm and 20 nm or less, respectively, so it is evident that high-resolution transmission electron microscopy (HRTEM) is the most powerful method to characterize the nanoscale structural features and elucidate their effects on the magnetic recording media performance.; In CoCrPtO perpendicular media, one of the objectives as far as the structure is concerned, is to obtain media of magnetically decoupled grains. This can be done by isolating the Co-rich magnetic grains from each other with non-magnetic oxygen-rich grain boundaries. In the present study, CoCrPtO media were prepared by systematically varying the thickness and oxygen content of the magnetic layer, and their effect on the resulting film structure was investigated by HRTEM. Nano-probe energy dispersive X-ray spectroscopy (EDS) combined with HRTEM was used to perform compositional analysis and study the segregation effects. Higher oxygen incorporation was effective to form a well-isolated grain structure with oxygen-rich grain boundaries. However, non-uniform film structure with high stacking fault density was also observed with high oxygen content.; More precise control on the film structure of the perpendicular media often involves template layers such as interlayers and seedlayers. The role of these layers is not limited to the enhancement of the preferred vertical c-axis orientation but can be extended to the control of the grain size, grain size distribution, and grain isolation in the magnetic film. The effects of Ta/Ru template layers on the structural and magnetic properties of the magnetic film were investigated. Moreover, a novel Ru/Ru+(metal oxide) interlayer structure for further inter-granular exchange decoupling in the magnetic film was introduced and evaluated. The formation of a small and isolated grain structure on the surface of the interlayer was achieved by the addition of a Ru+(metal oxide) on a conventional Ru interlayer, which resulted in further grain isolation in the magnetic film.