Numerical simulation of recorded bit in magneto-optical mediahaving thermally different protective layers

The influence of the thermal properties of the media in a multilayered magnetooptical disk on thermomagnetic recording characteristics such as recorded bit size and sensitivity has been investigated. Thermal properties have been simulated using several different dielectrics and metals for both undercoat and overcoat layers. Media with oxide layers represent those having low thermal diffusivity and large heat capacity, whereas nitride layers represent those with high thermal diffusivity and small heat capacity. Small domains are formed when an Al layer covers a Ta₂O₅ overcoat. Both recording sensitivity and bit-size increase for media with nitride layers compared with those having an Al top coat. When the same recording power is applied, media with oxide layers provide the most sensitive disks with the largest recorded bit-size among the structures studied. The results are explained by the differences in the heat capacities of the media together with the differences between the vertical and lateral heat flow throughout the layered structure