Magneto-optical recording medium

A magneto-optical recording medium comprising:

• a transparent substrate;
• a first transparent dielectric member, between 10 nm and 80 nm thick, made of one of the group of AlN, SiN and AlSiN, which is formed on the transparent substrate;
• a readout layer, 50 nm thick, made of Gd.sub.0.28 (Fe.sub.0.8 Co.sub.0.2).sub.0.72 or Gd.sub.0.25 Co.sub.0.75, which is formed on the first transparent dielectric member;
• a recording layer, 20 nm thick, made of Dy.sub.0.23 (Fe.sub.0.82 Co.sub.0.18).sub.0.77, which is formed on the readout layer;
• and
• a second transparent dielectric member, 50 nm thick, made of a nitride, which is provided on the recording layer so as to protect the recording layer.

A magneto-optical recording medium comprising:

• a transparent substrate;
• a first transparent dielectric member, 80 nm thick, made of one of the group of AlN, SiN and AlSiN, which is formed on the transparent substrate;
• a readout layer, 15 nm thick, made of one of the group of Gd.sub.0.28 (Fe.sub.0.8 Co.sub.0.2).sub.0.72, Gd.sub.0.25 Co.sub.0.75 and Dy.sub.0.3 (Fe.sub.0.7 Co.sub.0.3).sub.0.7, which is formed on the first transparent dielectric member;
• a recording layer, 15 nm thick, made of Dy.sub.0.23 (Fe.sub.0.82 Co.sub.0.18).sub.0.77, which is formed on the readout layer;
• a second transparent dielectric member, 30 nm thick, made of a nitride, which is provided on the recording layer so as to protect the recording layer;
• and
• a reflective film, 50 nm thick, provided on the second transparent dielectric member so as to enhance the magneto-optical effect.

A recording method, for recording on a magneto-optical recording medium, while applying a recording magnetic field, the magneto-optical recording medium including

• a recording layer, whereon information is magneto-optically recorded, and
• a readout layer, consisting essentially of an alloy of a rare-earth metal and a transition metal, having a compensation temperature higher than room temperature,
• wherein in-plane magnetization inherently occurs throughout said layer at room temperature and wherein, upon irradiation of a local area of said readout layer by application of a laser light beam having a non-uniform intensity distribution, a transition from the in-plane magnetization to vertical magnetization occurs in a portion of the local area as the temperature of the portion of the local area of the readout layer rises above a predetermined temperature, the portion being smaller than a diameter of the irradiating light beam, and wherein areas of said readout layer, other than said portion, maintain said in-plane magnetization, the recording method comprising the steps of:
• applying, to the local area of the readout layer, a first light beam so that a temperature increases up to a point in the vicinity of the Curie temperature in the portion of the local area, at which temperature the coercive force of the portion is greater than that of the recording layer;
• and
• applying, to the local area, a second light beam so that the temperature of the portion of the local area of the readout layer is raised to a point within a range of not less than the temperature at which a transition from the in-plane magnetization to the vertical magnetization occurs in the portion of the local area.

A magneto-optical recording medium comprising:

• a recording layer wherein information is magneto-optically recorded;
• and
• a readout layer, consisting essentially of an alloy of a rare-earth metal and a transition metal, having a compensation temperature higher than room temperature, wherein in-plane magnetization inherently occurs throughout said layer at room temperature, and upon irradiation of a local area of said readout layer by application of a laser light beam, a transition from the in-plane magnetization to vertical magnetization occurs in a portion of the local area as the temperature of the portion of the local area of the readout layer rises above a predetermined temperature, the portion being smaller than a diameter of the irradiating laser light beam, and wherein areas of said readout layer, other than said portion, maintain said in-plane magnetization,
• said readout layer being so arranged on said recording layer that the laser light beam is incident on said readout layer.

A recording method for recording on a magneto-optical recording medium while applying a recording magnetic field, the magneto-optical recording medium including a recording layer, whereon information is magneto-optically recorded, and a readout layer having a compensation temperature higher than room temperature,

• wherein in-plane magnetization inherently occurs at room temperature and wherein, upon heating of a local area, a transition from the in-plane magnetization to vertical magnetization occurs as the temperature of the heated local area of the readout layer rises above a predetermined temperature, the recording method comprising the steps of:
• heating said local area of the magneto-optical recording medium, so that a temperature thereof rises up to a point in the vicinity of the Curie temperature of the readout layer, at which temperature the coercive force of the readout layer is greater than that of the recording layer;
• and
• further heating said local area of said recording medium, so that the temperature of the readout layer is raised to a point within a range of not less than the temperature at which a transition from the in-plane magnetization to the vertical magnetization occurs.