Direct overwriting and super resolution using exchange-coupled magnetic multilayer disks

Exchange coupling between magnetic multilayers must be controlled for magnetic multilayers to make direct overwriting and super resolution possible in magneto-optical disks. Direct overwriting by light intensity modulation is made possible by using magnetic triple layers with a power margin of plus or minus 30%, a linear density of 0.8 mircrometer/bit and a track pitch of 1.4 micrometer. Super resolution by using magnetic quadri layers enables a linear density of 0.3 micrometer/bit, which is more than three times higher than the density for current MO disks.