fig3 with a main light beam 40 and a subsidiary light beam 80 with respective diameters of 1 and 5 microns the intensity of the main light beam was so selected that the vertical magnetic layer reaches 150 u00b0 160 u00b0 c whereby the coercive force of the recording track was reduced nearly to zero the intensity of the subsidiary light beam was so selected that the vertical magnetic layer reaches 100 u00b0 110 u00b0 c whereby the separating area shows a vertical magnetization of 113 g in the first layer and 40 g in the second layer as the result when the recording medium receives the main light beam but not the subsidiary light beam the recording track 12 receives a floating magnetic field of 200 oe from the surrounding separating areas 14 as shown in fig6 and when the recording medium receives both the main light beam and the subsidiary light beam the recording track 12 receives a floating magnetic field of 200 oe from the surrounding separating areas 14 as shown in fig7 since either floating magnetic field has an intensity of 200 oe enough for recording a bit p1 with a downward magnetization is formed on the recording.