Magneto-optical recording medium and method of reproducing information recorded on such medium

A magneto-optical recording medium comprising:

• a substrate transparent to a laser beam;
• a magnetic reproducing layer formed on said transparent substrate and having an in-plane easy direction of magnetization at a room temperature, and having an easy direction of magnetization perpendicular to a film plane when heated beyond a first predetermined temperature above said room temperature;
• a magnetic reproducing auxiliary layer formed on said reproducing layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, and having an in-plane easy direction of magnetization when heated beyond a second predetermined temperature above said room temperature;
• a magnetic switch layer formed on said reproducing auxiliary layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature;
• and
• a magnetic recording layer formed on said switch layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature;
• wherein respective Curie temperatures Tc1, Tc2, Tc3 and Tc4 of said reproducing layer, reproducing auxiliary layer, switch layer and recording layer satisfy the relationship of Tc1>Tc2>Tc4>Tc3.

A magneto-optical recording medium comprising:

• a substrate transparent to a laser beam;
• a magnetic reproducing layer formed on said transparent substrate and having an easy direction of magnetization perpendicular to a film plane in a specific region of said reproducing layer when heated, and having an in-plane easy direction of magnetization in any region other than said specific heated region having a temperature lower or higher than that of said specific heated region;
• a magnetic switch layer formed on said reproducing layer and having an easy direction of magnetization perpendicular to said film plane at a room temperature;
• and
• a magnetic recording layer formed on said switch layer and having an easy direction of magnetization perpendicular to a film plane at said room temperature;
• wherein respective Curie temperatures Tc1, Tc2 and Tc3 of said reproducing layer, switch layer and recording layer satisfy the relationship of Tc1>Tc3>Tc2.

A magneto-optical recording medium comprising:

• a substrate transparent to a laser beam;
• a magnetic reproducing layer formed on said transparent substrate and having an easy direction of magnetization perpendicular to a film plane when heated to a predetermined temperature, and having in-plane easy direction of magnetization when said reproducing layer is at a temperature lower or higher than said predetermined temperature;
• a nonmagnetic intermediate layer formed on said reproducing layer;
• and
• a magnetic recording layer formed on said nonmagnetic intermediate layer and having an easy direction of magnetization perpendicular to said film plane at a room temperature;
• wherein said reproducing layer has a Curie temperature higher than that of said recording layer, and said nonmagnetic intermediate layer is sufficiently thin to permit magnetostatic connection between said recording layer and said reproducing layer at said predetermined temperature.

A method of reproducing information recorded on a magneto-optical recording medium which comprises a substrate transparent to a laser beam, a magnetic reproducing layer formed on said transparent substrate and having an easy direction of magnetization perpendicular to a film plane at a room temperature, and having an in-plane easy direction of magnetization when heated beyond a first predetermined temperature above said room temperature, a magnetic switch layer formed on said reproducing layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, and a magnetic recording layer formed on said switch layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, wherein respective Curie temperatures Tc1, Tc2 and Tc3 of said reproducing layer, switch layer and recording layer satisfy the relationship of Tc1>Tc3>Tc2, said method comprising the steps of:

• irradiating said laser beam to said recording medium to thereby heat the same below the Curie temperature of said recording layer;
• and
• forming, within a beam spot, a temperature distribution having a low temperature transfer region having a temperature below the Curie temperature of said switch layer wherein the magnetization of said recording layer is transferred to said switch layer and said reproducing layer by switched connection, and a high temperature mask region having a temperature equal to or above the Curie temperature of said switch layer, wherein said switch layer is heated beyond the Curie temperature thereof so that the magnetization of said reproducing layer is directionally turned from perpendicular to said film plane to in-plane one thereto.

A method of reproducing information recorded on a magneto-optical recording medium which comprises a substrate transparent to a laser beam, a magnetic reproducing layer formed on said transparent substrate and having an in-plane easy direction of magnetization at a room temperature, and having an easy direction of magnetization perpendicular to a film plane when heated beyond a first predetermined temperature above said room temperature, a magnetic reproducing auxiliary layer formed on said reproducing layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, and having an in-plane easy direction of magnetization when heated beyond a second predetermined temperature, a magnetic switch layer formed on said reproducing auxiliary layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, and a magnetic recording layer formed on said switch layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, wherein respective Curie temperatures Tc1, Tc2, Tc3 and Tc4 of said reproducing layer, reproducing auxiliary layer, switch layer and recording layer satisfy a relationship of Tc1>Tc2>Tc4>Tc3, said method comprising the steps of:

• irradiating said laser beam to said recording medium to thereby heat the same below the Curie temperature of said recording layer;
• and
• forming, within a beam spot, a temperature distribution having a low temperature mask region having a temperature below the Curie temperature of said switch layer wherein the magnetization of said reproducing layer is directionally turned from perpendicular to said film plane to in-plane one thereto, an intermediate temperature transfer region where the magnetization of said recording layer is transferred to said reproducing layer via said switch layer and said reproducing auxiliary layer, and a high temperature mask region having a temperature equal to or above the Curie temperature of said switch layer wherein said switch layer is heated beyond the Curie temperature thereof so that the magnetization of each of said reproducing auxiliary layer and said reproducing layer is directionally turned from perpendicular to said film plane to in-plane thereto.

A method of reproducing information recording on a magneto-optical recording medium which comprises a substrate transparent to a laser beam, a magnetic reproducing layer formed on said transparent substrate and having an easy direction of magnetization perpendicular to a film plane in a specific region of said reproducing layer that is heated, and having an in-plane easy direction of magnetization in any region other than said specific heated region having a temperature lower or higher than that of the temperature of said specific heated region, a magnetic switch layer formed on said reproducing layer and having an easy direction of magnetization perpendicular to said film plane at a room temperature, and a magnetic recording layer formed on said switch layer and having an easy direction of magnetization perpendicular to said film plane at said room temperature, wherein respective Curie temperatures Tc1, Tc2 and Tc3 of said reproducing layer, switch layer and recording layer satisfy a relationship of Tc1>Tc3>Tc2, said method comprising the steps of:

• irradiating said laser beam to said recording medium to thereby heat the same below the Curie temperature of said recording layer;
• and
• forming, within a beam spot, a temperature distribution having a low temperature mask region having a temperature below the Curie temperature of said switch layer wherein the magnetization of said reproducing layer is directionally turned from perpendicular to said film plane to in-plane thereto, an intermediate temperature transfer region where the magnetization of said recording layer is transferred to said reproducing layer via said switch layer, and a high temperature mask region having a temperature equal to or above the Curie temperature of said switch layer so that the magnetization of said reproducing layer is directionally turned from perpendicular to the plane to in-plane thereto.

A method of reproducing information recorded on a magneto-optical recording medium which comprises a substrate transparent to a laser beam, a magnetic reproducing layer formed on said transparent substrate and having an easy direction of magnetization perpendicular to a film plane when heated to a predetermined temperature, and having an in-plane easy direction of magnetization when heated to a temperature lower or higher than said predetermined temperature, a nonmagnetic intermediate layer formed on said reproducing layer, and a magnetic recording layer formed on said nonmagnetic intermediate layer and having an easy direction of magnetization perpendicular to said film plane at a room temperature, wherein said reproducing layer has a Curie temperature higher than that of said recording layer, and said nonmagnetic intermediate layer is sufficiently thin to permit magnetostatic connection between said recording layer and said reproducing layer at said predetermined temperature, said method comprising the steps of:

• irradiating the laser beam on said recording medium to thereby heat the same to a temperature below the Curie temperature of said recording layer;
• and
• forming, within a beam spot, a temperature distribution having a low temperature mask region having a temperature lower than said predetermined temperature wherein the magnetization of said reproducing layer is directionally turned from perpendicular to the film plane to in-plane thereto, an intermediate temperature transfer region where the magnetization of said recording layer is transferred to said reproducing layer by magnetostatic connection, and a high temperature mask region having a temperature higher than said predetermined temperature wherein the magnetization of said reproducing layer is directionally turned from perpendicular to said film plane to in-plane thereto.