Magneto-optical recording medium having large kerr rotational angle in short wavelength range

摘要

In a magneto-optical recording medium, a protective layer 14, a first magnetic layer 11 formed of a light rare earth element--heavy rare earth element--transition metal alloy, a second magnetic layer 12 formed of a light rare earth element--heavy rare earth element-- transition metal alloy, a third magnetic layer 13 formed of a light rare earth element-- heavy rare earth element--transition metal alloy, another protective layer 15, and a reflection layer 16 are laminated in sequence on a transparent substrate 10. The first, second and third magnetic layers are sandwiched so as to form a recording film 17. The compositions of the first and third magnetic layers are so selected as to provide a large Kerr rotational angle in a short wavelength range (400 to 700 nm), which is high in the ratio of light rare earth element. On the other hand, the composition of the second magnetic layer is so selected as to be prominent in the characteristics for forming a perpendicular magnetized film, which is high in the ratio of heavy rare earth element. The recording film 17 formed by sandwiching the first, second and third magnetic layers has a large Kerr rotational angle in a short wavelength range as a whole, and further provides a high coercivity. The recording film 17 is formed thin (400 angstrom or less) so that light can transmit sufficiently therethrough. Further, when the three layers of sandwich structure is combined with the reflection layer 16, a more larger Kerr rotational angle can be obtained.