BARIUM FERRITE THIN-FILM RECORDING MEDIA

Both longitudinal and perpendicular barium ferrite thin films are bein g pursued as overcoatless magnetic recording media. In this paper, pri or research on thin-film Ba ferrite is reviewed and the most recent re sults are presented. Self-textured high-coercivity longitudinal Ba fer rite thin films have been achieved using conventional rf diode sputter ing. Microstructural studies show that c-axis in-plane oriented grains have a characteristic acicular shape, while c-axis perpendicularly or iented grains have a platelet shape. Extended X-ray absorption fine st ructure (EXAFS) measurements indicate that the crystal orientations ar e predetermined by the structural anisotropy in the as-sputtered 'amor phous. state. Recording tests on 1500 Oe coercivity longitudinal Ba fe rrite disks show performance comparable with that of a 1900 Oe Co allo y disk. To further improve the recording performance, both grain size and aspect ratio need to be reduced. Initial tribological tests indica te high hardness of Ba ferrite thin films. However, surface roughness needs to be reduced. For future ultrahigh-density contact recording, i t is believed that perpendicular recording may be used. A thin Pt unde rlayer has been found to be capable of producing Ba ferrite thin films with excellent c-axis perpendicular orientation.