PURPOSE: To obtain high recording density and to enable ultra-high density recording and reproducing by controlling the apparent coercive force in the direction perpendicular to the plane of a composite medium in a prescribed range.
CONSTITUTION: The two-layered medium forms a high permeability layer having 0.7μm thickness on a glass substrate and forms a vertical magnetized film having 0.2μm thickness thereon. The satd. magnetization of the vertical magnetized film is 300emu/cc and the coercive force is changed by changing sputtering conditions. The large density is obtd. where the apparent coervice force of the composite two-layered medium is in a 400W1,200e, more perferably 55W850e range as shown in the figure when the recordable density is measured by changing the coercive force.
SHIROISHI YOSHIHIRO
TSUMITA NORIKAZU
HISHIYAMA SADAO
Next Patent: MAGNETIC DISK AND ITS PRODUCTION