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Media with low noise at high transition density that demonstrate satisfactory recording performance at an areal density, of 1 Gb/in/sup 2/ when combined with dual-element (magnetoresistive read/inductive write) heads have been fabricated. A media structure of C/CoPtCr/Cr was utilized over a range of magnetic parameters: coercivity approximately=1600-1800 Oe, remanence-thickness product approximately=0.7*10/sup -3/ emu/cm/sup 2/, and coercive squareness approximately=0.7-0.8. 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- mu m track width, and the absence of supralinear increase in media noise power with linear density up to 3000-3500 fc/mm. The -6-dB rolloff densities are in the range 4000-5000 fc/mm. Overwrite values are typically better than 40 dB. Microstructural analysis indicates that the reduced transition noise of the present media is due to physical separation of the grains in the magnetic films, which reduces the exchange coupling between the magnetic grains. The reduced coercive squareness of the low-noise media degrades the overwrite performance and is also expected to decrease the linear density resolution of the media.>
Yogi et al. (Mon,) studied this question.