Recording Sensitivity and Lifetime Estimate of a Magneto-Optical Disk

Lifetime estimates of a magneto-optical disk which uses GdTbFe as the magnetic layer, AlN as dielectric layers, and Al as the reflective layer, were discussed. In order to study the aging characteristics, accelerated aging tests were performed by changing the ambient temperature (between 20 and 100°C in air). In addition to the coercivity, the recording sensitivity, which was evaluated with the recorded bit length, was chosen as the basis for quantitative estimates of the lifetime. As the aging time grew longer, the recording sensitivity tended to decrease. The higher the aging temperature, the larger was the rate of decrease. Using the Arrhenius method, it was estimated that magneto-optical disks with the quadri-layer structure described have an expected lifetime of about 18 years, sufficient for optical data storage applications.