Self biasing thermal magneto-optic medium
AssigneeInternational Business Machines Corporation
InventorsShu S. Sun, Curt W. Laumann
Life of this patent
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Abstract
A layer in a magnetic storage medium provides a biasing magnetic field for writing data. The layer exhibits a net magnetization with an orientation in a first direction when the layer is at a temperature below its compensation temperature and a net magnetization with an orientation in a second direction different from the first direction when heated as by a laser to a temperature above its compensation temperature, but below its Curie point temperature.
Claims29
A thermally written magnetic data storage medium for retaining domains of desired magnetic field orientations representative of the data comprising:
- data layer means for retaining the domains having desired magnetic field orientations;
- and
- bias layer means coupled to the data layer means for providing a biasing field as a function of the temperature of the bias layer means for obtaining the domains of desired magnetic field orientations in the data layer.
Apparatus for providing a biasing magnetic field for a magnetic storage device having domains of magnetization representative of data, the apparatus, comprising:
- a ferrimagnetic layer having a net magnetization with an orientation in a first direction when such layer is at a temperature below its compensation temperature and a net magnetization with an orientation in a second direction different from the first direction at a temperature above its compensation temperature, but below its Curie point temperature, said layer providing the biasing magnetic field for establishment of the domains of magnetization.
A method of writing data on an opto-magnetic storage medium having a first layer for retaining domains of magnetization having orientations representative of data and a second biasing layer having a compensation temperature less than, and a Curie temperature greater than the Curie temperature of the first layer, comprising the steps of:
- heating a selected portion of the medium to a temperature greater than the Curie temperature of the first layer, but less than the Curie temperature of the second layer;
- and
- cooling the selected portion of the medium to a temperature substantially less than the compensation temperature of the second layer such that the orientation of magnetization of the portion of the first layer is changed in a desired manner.
A method of returning magnetization of a self biasing magnetic medium to a predetermined direction, the medium having a first layer for retaining domains of magnetization representative of data, a second ferrimagnetic layer for providing a biasing magnetic field for obtaining the domains of magnetization in the first layer, and a third layer for providing a magnetic biasing field of predetermined direction, comprising the steps of:
- heating the first and second layers to a temperature above both the Curie temperature of the first layer and the Curie temperature of the second layer to reduce their magnetizations to substantially zero;
- and
- cooling the first and second layers to a temperature below the compensation temperature of the second layer and the Curie temperatures of the first and second layers such that the orientation of magnetization of the first and second layers is in the predetermined direction.
Dependencies are inferred from the claim text.