Browse Prior Art Database

Overwritable Exchange Coupled Five Layer Magneto-optic Medium

IP.com Disclosure Number: IPCOM000122408D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Lin, CJ: AUTHOR

Abstract

Disclosed is an overwritable magneto-optic medium which consists of five exchange-coupled magneto-optic layers. This medium can be used in a current magneto-optical storage device which utilizes an optical read/write beam and one bias magnetic field. An exemplary set of materials for the layers of the disclosed magneto-optic medium structure is shown in the figure.

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Overwritable Exchange Coupled Five Layer Magneto-optic Medium

      Disclosed is an overwritable magneto-optic medium which
consists of five exchange-coupled magneto-optic layers. This medium
can be used in a current magneto-optical storage device which
utilizes an optical read/write beam and one bias magnetic field.  An
exemplary set of materials for the layers of the disclosed
magneto-optic medium structure is shown in the figure.

      This overwritable exchange-coupled five-layer magneto-optic
medium allows better performance control over a four-layer
exchange-coupled overwritable magneto-optic medium.  The improvement
is achieved by the addition of a 'copying layer', as shown in the
figure.  The Curie temperature of the 'reference layer' has to be
much higher than that of the 'memory layer', and the room temperature
coercivity of the 'memory layer' has to be significantly larger than
that of the 'reference layer'.

      The 'permanent layer' has such a high Curie temperature Tc
(e.g., TbCo with Tc over 400oC) that its magnetization stays
permanent (i.e., never changes during thermomagnetic recording) after
it is initialized once for all by a high magnetic field.  The
'switching layer' has relatively the lowest Curie temperature, such
that during the cooling process of the thermomagnetic writing the
initialization of the 'reference layer' by exchange-coupling through
the 'switching layer' to the 'permanent layer' takes place only after
the domains whic...