Film Microstructure and Properties of CoPtCr-SiO_2 Perpendicular Media

Abstract

SiO_2 added CoPtCr magnetic layer is employed for the perpendicular recording media. The microstructure, magnetic properties, and recording performance of these media are discussed. Very fine grain of the size of less than 7 nm, surrounded by grain boundaries which mainly consisted of silicon oxide, are realized. The addition of SiO_2 to CoPtCr is very effective to enhance well isolated fine grain structure without disturbing the epitaxial growth of the CoPtCr grains on Ru underlayer. The media show a large perpendicular anisotropy K_u of 〜3.5 × 10^6 erg/cm^3 and a K_uV/kT value more than 80, even at the CoPtCr-SiO_2 thickness of 12 nm, resulting in a high coercivity Hc (〜4 kOe) and high squareness M_r/M_S of 0.9. The CoPtCr-SiO_2 medium shows excellent SNR performance together with high thermal stability at very thin thickness, indicating a great potential for high-density perpendicular recording media.