Observation and simulation of 0.3 mu m length domain on a high speed rotating magneto-optical disk

The magnetooptical recording characteristics of a 0.2-0.3- mu m-length domain were studied using a magnetic field modulation method. The ultimate goal of the investigation, performed on an extremely high-density magnetooptical disk, was to realize high-speed rotating 5.25-in disks. Through optical observation, it was found that domains of 0.3- mu m length could be recorded separately under the condition of 15.1 m/s linear velocity and 25.2 MHz. However, the domain shape became more irregular with increasing recording power and linear velocity. This could be explained by calculated results showing that the domain wall temperature when the magnetic field is reversed becomes higher as the power or the velocity increases. It was observed that the domain shape of a quadri-layer structure disk with a reflective layer having a higher thermal conductivity, such as Al film, is more irregular. This is explained by the difference in temperature profiles obtained from simulation.>