Compositional dependence of recording noise in amorphous rare-earth–transition-metal magneto-optical disks

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Abstract
The compositional dependence of recording-power sensitivity and recording-noise characteristics of TbFeCo and TbDyFeCo films have been studied systematically. The sensitivity depends on the compositional ratio of rare earth (RE) and transition metal (TM) rather than on Co content. This is explained by the fact that the temperature at which the coercive force (Hc ) coincides with the bias magnetic field of 500 Oe, hereafter denoted as T′, varies drastically by altering the RE-to-TM ratio. High recording noise is observed for compositions having Tcomp close to TC. When TC−Tcomp≳70 °C, optimal carrier-to-noise ratios are obtained. These results are explained qualitatively by the behavior of domain-wall motion in the vicinity of the magnetically reversed domain.