Magneto-optical recording medium whereon overwriting is permitted by light intensity modulation

A magneto-optical recording and reproducing device for recording on, or reproducing from, a magneto-optical recording medium which comprises

• a first magnetic layer made of an alloy of a rare-earth metal and a transition metal;
• a second magnetic layer, made of an alloy of a rare-earth metal and a transition metal, formed on said first magnetic layer;
• and
• a third magnetic layer, made of an alloy of a rare-earth metal and a transition metal, formed on said second magnetic layer, wherein:
• said first magnetic layer is made of DyFeCo and has a perpendicular magnetization in a temperature range between room temperature and its Curie temperature, said Curie temperature being in a range between 100.degree. C. and 250.degree. C., and
• a coercive force at room temperature of said first magnetic layer is at or above 5k Oe;
• said second magnetic layer is made of GdFeCo and has properties such that its Curie temperature is higher than the Curie temperature of said first magnetic layer, a coercive force thereof at room temperature is negligible and that it has an in-plane magnetization at room temperature and a transition occurs therein from the in-plane magnetization to a perpendicular magnetization at above 80.degree. C.;
• and
• said third magnetic layer is made of a material selected from the group consisting of GdDyFeCo and DyFeCo, and has properties such that it has a perpendicular magnetization in a temperature range between room temperature and its Curie temperature, its Curie temperature falls within a range between 150.degree. C. and 400.degree. C., and that the coercive force thereof at room temperature is at or below 3k Oe, thereby permitting an initializing magnetic field and a recording magnetic field to have a common direction, and thereby facilitating magnetic coupling between said third magnetic layer and said first magnetic layer only at an elevated temperature, such coupling being blocked at room temperature by said second magnetic layer,
• said magneto-optical recording and reproducing device comprising:
• means for generating an initializing magnetic field for use in initializing said third magnetic layer when overwriting;
• light projection means for projecting a light beam onto said magneto-optical recording medium according to information;
• and
• means for generating a recording magnetic field to be applied to said third magnetic layer,
• wherein the initializing magnetic field, generated from said means for generating the initializing magnetic field, and the recording magnetic field, generated from said means for generating the recording magnetic field, have the same direction.