CoPtCr-SiO/sub 2/ granular media for high-density perpendicular recording

SiO/sub 2/ 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 with size of less than 7 nm, surrounded by grain boundaries mainly consisting of silicon oxide, are realized. The addition of SiO/sub 2/ to CoPtCr is very effective in enhancing the well-isolated fine grain structure without disturbing the epitaxial growth of the CoPtCr grains on the Ru underlayer. The media show a large perpendicular anisotropy K/sub u/ of /spl sim/4 /spl times/ 10/sup 6/ erg/cm/sup 3/ and a K/sub u/V/kT value of more than 80, even at a CoPtCr-SiO/sub 2/ thickness of 12 nm, resulting in a high coercivity H/sub c/ (/spl sim/4 kOe) and high squareness M/sub r//M/sub s/ of /spl sim/0.96. The CoPtCr-SiO/sub 2/ medium shows excellent signal-to-medium-noise ratio performance together with high thermal stability at very thin thickness, indicating great potential for high-density perpendicular recording media.