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Fe-Pt-Ag-SiO2 and Fe-Pt-Ag-C granular recording media with an L10 ordered structure were fabricated using an in-line sputtering system with full-surface alloy targets. To understand the degree of ordering, the x-ray diffraction intensity ratio of a superlattice peak to a fundamental peak was measured for various samples. Some samples showed large intensity ratios despite having low anisotropy energy. This can be explained by the simple theory that the relative intensity at a low diffraction angle increases for samples with weaker preferred orientation. That is, the intensity ratio is affected not only by the degree of ordering but also by the crystalline texture quality. The larger intensity ratio of Fe-Pt-Ag-C media than that of Fe-Pt-Ag-SiO2 media was interpreted as the degraded Fe-Pt(001) texture of Fe-Pt-Ag-C media. Thus, good Fe-Pt(001) texture needs to be achieved without deteriorating the well-isolated granular structure in Fe-Pt-Ag-C media. more...

The effect of the magnetic and structural properties on recording performance was investigated. Well grain-isolated media were obtained by adding boron and oxygen into the [Co/Pd]n multilayer and cooling the substrate. We found that the recorded bit size could be decreased by reducing the magnetic cluster size. Twenty-flve-nm bits were successfully recorded on the improved media with a magnetic cluster size of about 30 nm. more...

To evaluate properties of an initial growth layer for CoCrPt-SiO 2 perpendicular recording media, an initial growth layer has been investigated by micromagnetic simulation with initial layer model. It was found that with the initial growth layer, the in-plane magnetization Min shows a small jump at 0-field, leading to an additional peak around 0-field in 4 pi dMin/dH curve. The (additional) peak height increases with the increase in inter- lower subgrain exchange areal energy densities wi and thickness of the initial layer and also decreases in the anisotropy energy for the initial layer. Considering the change of the average anisotropy energy as a function of the thickness of recording layer, wi for a CoCrPt-SiO2 perpendicular recording medium with Ru/Ru-SiO2 intermediate layer is in the range from 0.5 to 0.6 erg/cm2 and roughly 30% smaller than those with a Ru intermediate layer more...

CoB/Pd multilayer films with a PtB/Pd/MgO intermediate layer were deposited on a soft-magnetic underlayer or on seeded substrates. A TEM analysis revealed that the multilayer films have a well-separated columnar structure just above an MgO layer. This structure may be initiated by the difference in the wetting nature of nonmetallic MgO and metallic Pd, and may be enhanced by the PtB layer. These boundaries were found to act in reducing the exchange coupling, resulting in an improvement in recording performance. more...

An intermediate layer for double-layer perpendicular media was investigated to weaken the intergranular exchange coupling of the CoCrPt alloy recording layer and to reduce the medium noise. When the intermediate layer was composed of an ultrathin Ta layer formed on an MgO film, the coercivity, thermal decay characteristics, and signal-to-noise ratio improved. The required average thickness of Ta layer was within 0.1 to 0.3 nm. The result suggests that the ultrathin Ta layer has an isolated island shape and plays the role of a template for the magnetically isolated grain growth of the recording layer. more...

We have investigated the role of the Ru underlayer for the segregated structure formation of CoCrPt-SiO2 granular thin film to improve the recording performance of CoCrPt-SiO2 perpendicular magnetic recording media. The coercivity of the granular film decreases with decreasing Ru layer thickness, which comes from the change in the segregated structure. Formation of an oxide grain boundary is needed to obtain higher coercivity. According to a morphology analysis, the Ru layer roughness is closely related to the coercivity. The results indicate that the oxide grain boundary formation of the granular layer is enhanced by the roughness of the Ru underlayer. The shapes of the Ru grains probably serve as a template in CoCrPt grain growth and oxide grain boundary formation. As one of the methods for enhancing the roughness of the Ru underlayer, an island shape growth on the low surface energy materials is applicable. The roughness of the Ru layer was increased using a Pd/MgO/Pd seed layer and high coercivity was successfully obtained even when the Ru layer thickness was 3 nm. more...