Characteristics of magnetic field modulation recording on GdDyFeCo magneto-optical disk were investigated. GdDyFeCo recording layer was deposited by two source RF magnetron sputtering method. The compositionally modulated films changed their thermo-magnetic properties with the modulation periodicity and exhibited minimum recording field (Hs) value at modulation period of 2Å. According to the observed dependence of Hs on GdDy contents, relatively low Hs value was obtained in the rare-earth rich region near the compensation composition. By optimizing the GdDy contents, recording magnetic field transition time less than 250 ns could be obtained at recording frequency of 720 kHz.
