Magneto-optical recording medium having two magnetic layers with the same curie temperature

• US 5,487,046 A
• Filed: 07/28/1994
• Issued: 01/23/1996
• Est. Priority Date: 05/31/1991
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Tokita, Toshiaki, Tanaka, Motoharu, Watada, Atsuyuki
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): DINH, TAN X
• Application Number:
  US08/282,212
• Time in Patent Office: 544 Days
• Field of Search: 369/13, 369/14, 369/275.2, 369/273, 360/114, 360/59, 365/122, 428/694 ML, 428/694 R, 428/694 MT, 428/694 RE, 428/694 MM, 428/694 EC
• US Class Current: 369/13.49
• CPC Class Codes: G11B 11/10506 by modulating only the light beam of the transducer
• CPC Class Codes: G11B 11/10515 Reproducing compensating pit shift G11B11/1053
• CPC Class Codes: G11B 11/10521 using a single light spot
• CPC Class Codes: G11B 11/10582 Record carriers characterised by the selection of the material or by the structure or form

Abstract

A magneto-optical recording method for recording information in an overwrite mode in a magneto-optical recording medium by the application of a laser beam is disclosed. The magneto-optical recording medium includes a substrate, and at least two magnetic recording layers overlaid thereon, with an exchange force working at least between the two magnetic recording layers, and the Curie temperature of each of the two magnetic recording layers being substantially the same. The magneto-optical recording method includes the step of conducting overwriting information by changing the power of the laser beam to be applied to at least two different levels, one at which the magnetic recording layers are heated to a temperature near or higher than the Curie temperature, and the other at which the magnetic recording layers are heated to a temperature lower than the Curie temperature, while a magnetic field is applied to the magneto-optical recording medium in one direction, in accordance with signals to be recorded in the magneto-optical recording medium, and this recording method requires only one initialization by the application of the magnetic field, but does not require any further initialization thereafter.

Claims

1. A magneto-optical recording medium comprising

a substrate and at least two magnetic recording layers overlaid thereon, including a first magnetic recording layer and a second magnetic recording layer in view of the incident direction of a laser beam to be applied thereto for recording information and/or reproducing recorded information, each of said first and second magnetic recording layers comprising as the main component an amorphous alloy of a rare earth metal and an iron-family transition metal, and constituting a perpendicular magnetic layer, the Curie temperatures of said first magnetic recording layer and said second magnetic recording layer being substantially the same, said first magnetic recording layer being bonded to said second magnetic recording layer through exchange force, the compensation point of said first magnetic recording layer being near room temperature, the magnetic moment of said rare earth metal of said alloy in said second magnetic recording layer exceeding the magnetic moment of said iron-family transition metal of said alloy in said second magnetic recording layer, and the compensation point of said second magnetic recording layer being not present in the range between room temperature and the Curie temperature of said second magnetic recording layer.