LONGITUDINAL MEDIA FOR 1-GB/IN2 AREAL DENSITY

Media with low noise at high transition density have been fabricated that demonstrate satisfactory recording performance at an areal density of I Gbit/in2 when combined with dual-element (magnetoresistive read/inductive write) heads. A media structure of C/CoPtCr/Cr was utilized over a range of magnetic parameters: coercivity ~1600–1800 Oe, remanance-thickness product ~ 0.7 x 10.3 emu/cm2and coercive squareness ~ O.7-0.8. Media noise reduction was accomplished by optimizing the film growth characteristics to reduce intergranular exchange coupling in the magnetic layer. The low noise characteristics of the media are manifested in their low transition jitter values, 5 nm for 3 μm track width, and the absence of supra-linear increase in media noise power with linear density up to 3000–3500 fc/mm. The -6dB rolloff densities are in the range 4000-5000 fc/mm. Overwrite values are typically better than 40 dB. The influence of coercive squareness, S, on media noise and overwrite was studied for S values between 0.5 and 0.9 in the course of this work. © 1990 IEEE