BE-CR-DOPED HIGH-CORROSION-RESISTANT MAGNETOOPTICAL DISKS

The addition of Be to TbFeCo thin-film layers results in the gradual deterioration of carrier-to-noise ratio (CNR) and optimized recording power P(w) compared with that of Cr. Be and Cr composite-doped disks, whose CNR maintain over 54 dB at a recording frequency of 1 MHz, prevent bit-error-rate (BER) levels from increasing in accelerated environmental tests. It is noted that even prior to environmental stability testing, BER of Be-Cr composite-doped disks is less than that of nondoped disks. From the results obtained by Auger electron spectroscopy analysis, it is explained that this difference is caused by fluctuations in the reflections of disks resulting from varying thicknesses of extra layers formed as a result of reaction between TbFeCo and SiN. Finally, through the write-erase cycle test and differential scanning calorimetry analysis, it has been demonstrated that Be-Cr-doped disks possess a higher thermal durability than nondoped disks.