Microstructure and magnetic properties of CoPtCr-SiO2 perpendicular recording media

SiO₂ added CoPtCr magnetic layers are employed for perpendicular recording media. The microstructure, magnetic properties, and recording performance of these media are discussed. Very fine grains (size ∼7 nm), surrounded by amorphous-like grain boundaries, are realized together with good c-axis orientation normal to the film plane. It is considered that the addition of SiO₂ to CoPtCr is very effective in realizing a well-isolated fine-grain structure without disturbing the epitaxial growth of CoPtCr grains on the Ru underlayer. The medium with a 12-nm-thick recording layer shows a large perpendicular anisotropy K_u of ∼4 × 10⁶ erg/cm³, and high coercivity H_c of ∼4 kOe. Moreover, the medium shows excellent SNR performance together with high thermal stability, indicating great potential for high-density perpendicular recording media.