Domain and write–read characteristics for magnetic field modulated magneto‐optical disk with high data transfer rate

Magneto‐optical domain shape and write–read characteristics were investigated in an overwrite scheme using a flying magnetic head. Through domain observation and domain shape numerical simulation on magnetic film, it was found that ‘‘tails’’ of domains must be shortened to increase the carrier‐to‐noise ratio (C/N) at high‐density conditions. To reduce the length of domain tails, isotherms on the magnetic film must be circular. For quick heat flow, we constructed a quadrilayered disk which has a thin metal film. C/N of the disk was about 50 dB at 7.4 MHz (0.75‐μm domain length) with linear velocity 11.3 m/s. Compared with the light power modulation method, the magnetic field modulation method is a more suitable overwrite technique, since the thermal profile is the same for any recording mark length.