Magneto-optical recording medium, disk and method of manufacturing the same
AssigneeNippon Steel Corporation
InventorsKenji Shimokawa, Hitoshi Dohnomae, Toshio Mukai, Kengo Shimanoe
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Abstract
A high density magneto-optical recording medium utilizing a polycrystalline garnet two-layer film. The film thickness of an under layer of the garnet polycrystal on a glass substrate is made 100 nm or less, and a crystal grain diameter of a recording layer formed thereon is made 0.1 .mu.m or less. Furthermore, the under layer is demagnetized at room temperature. With this, a bit having a regular shape can be written, thus reducing medium noise by a large margin.
Claims24
A magneto-optical recording medium comprising:
- a substrate;
- a first layer of polycrystalline garnet film formed on said substrate, for serving as an under layer, said first layer having a Curie temperature lower than a predetermined temperature, said predetermined temperature being within a range from -10.degree. C. to +50.degree. C., so that said first layer has a non-magnetic characteristic at said predetermined temperature;
- and
- a second layer of polycrystalline garnet film, formed on said first layer, for recording information, said second layer having a Curie temperature higher than said predetermined temperature so that said second layer has a magnetic characteristic at said predetermined temperature.
A method of manufacturing a magneto-optical recording medium, comprising the steps of:
- forming on a substrate a first layer of polycrystalline garnet film for serving as an under layer such that a thickness of said first layer becomes 100 nm or less;
- applying reverse sputtering processing to a surface of said first layer of polycrystalline garnet film;
- and
- forming on said first layer a second layer of polycrystalline garnet film for recording information such that a crystal grain diameter of said second layer becomes 0.1 .mu.m or less and crystal lattice constants of said first and second layers becomes different from each other by .+-.0.3% or more.
A method of manufacturing a magneto-optical recording medium, comprising the steps of:
- forming on a substrate a first layer of polycrystalline garnet film for serving as an under layer such that a thickness of said first layer becomes 100 nm or less, said first layer having a Curie temperature lower than a predetermined temperature, said predetermined temperature being within a range from -10.degree. C. to +50.degree. C., so that said first layer has a non-magnetic characteristic at said predetermined temperature;
- applying reverse sputtering processing to a surface of said first layer of polycrystalline garnet film;
- and
- forming on said first layer a second layer of polycrystalline garnet film for recording information such that a crystal grain diameter of said second layer becomes 0.1 .mu.m or less and crystal lattice constants of said first and second layers become different from each other by .+-.0.3% or more, said second layer having a Curie temperature higher than said predetermined temperature so that said second layer has a magnetic characteristic at said predetermined temperature.
Dependencies are inferred from the claim text.