反強磁性的な磁化結合による垂直磁気記録媒体裏打層の単磁区化(磁気記録媒体)

概要

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CoZrNb films stacked with non-magnetic interlayer films (Ru, Cu, or C) were deposited on 2.5-inch φ glass disks, for use as soft underlayers (SUL) of perpendicular recording media, and the effect of interlayer coupling on their domain structure was investigated. CoZrNb films stacked with a thin Ru interlayer show anti-ferromagnetic interlayer coupling dependent on the thickness of the Ru layer. The anti-ferromagnetic coupling field, H_u, was 〜24 Oe for CoZrNb (50 nm)/Ru (1.8 nm)/CoZrNb (50 nm) film, for instance, and the value of H_u is nearly proportional to the inverse of the CoZrNb thickness. Domain observation by the Bitter method indicates that a single-domain state was successfully realized over a whole disk by the anti-ferromagnetic interlayer coupling, when the thickness of the CoZrNb layer was less than 50 nm (number of stacked layers : 2-4, total SUL thickness : 100-200 nm). Weak noise due to a stray field from the CoZrNb layer was detected by observation using a read head, even in single-domain disks, and is probably due to magnetization ripples in the CoZrNb layer. However, the stray field was no longer detected in disks annealed in an applied magnetic field, perhaps because of the reduction of the magnetization ripple. The anti-ferromagnetic interlayer coupling was found to be effective for realizing a single-domain SUL layer.
2003-04-01