Role of Nucleation Field of Media in Perpendicular Magnetic Recording (Invited)

概要

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Role of the nucleation field in perpendicular magnetic recording was studied using micromagnetic and Monte Carlo calculations. Three different types of perpendicular media with the same grain size of 7.5 nm and the same value of KV/kT of 37 but with different K value have been assumed. The three types of media showed different nucleation field in hysteresis loops. A larger nucleation field resulted from smaller h_m and larger h_e. If the nucleation field was large enough to resist the trail field of head, reverse domain was not formed in the bit. Therefore, the medium noise was significantly reduced in that case. SNR increased in this type of media with increasing exchange parameter. The increase of SNR is related to decreased noise rather than increased signal with increasing the exchange parameter. The main source of noise seems to be DC erase noise not transition noise. In the point of view of media, areal recording density of 90 Gbit/inch^2 (564kfci×160ktpi) would be attainable in perpendicular recording with single magnetic layer and ring type head when the medium has a large nucleation field. To realize these, however, there should be improvement of writing head because of limitation of head leakage field in a narrow gap head.
社団法人電子情報通信学会の論文
1999-11-09