Dynamic magnetic information storage or retrieval – General recording or reproducing – Thermomagnetic recording or transducers
Reexamination Certificate
2000-03-27
2004-06-22
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Thermomagnetic recording or transducers
C360S324000, C360S097010
Reexamination Certificate
active
06754020
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-248858, filed Sep. 2, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic recording/reproduction apparatus for recording information with magnetism and magnetic recording media used for the same, especially a magnetic recording apparatus wherein heat is applied when recording and magnetic recording media used for the same.
Research heretofore has shown that when attempting to improve recording density of magnetic recording, it is difficult to make reduction of media noise and improvement of resistance to thermal fluctuation compatible.
Use of materials with elevated magnetic anisotropy energy of magnetic film of the media may be considered as one of the solutions. However, when a material with increased anisotropy field is used in order to raise magnetic anisotropy energy of the magnetic layer, a problem of difficulty of recording has occurred because there is a limit in magnetic field of a magnetic recording head.
In recent years heat assisted recording has been proposed as one of the methods to solve such a problem. Heat assisted recording is a technology with which to stabilize thermal fluctuation by heating the recording region of the medium during recording to reduce anisotropy field Hk of the magnetic film, and thus, facilitating recording, and by raising anisotropy field through recovering the temperature after recording.
A graph representing the relations of temperature with anisotropy field and activation magnetic moment is shown in FIG.
1
.
In the figure, graph
901
represents the relation between temperature and anisotropy field, and graph
902
represents the relation between temperature and activation magnetic moment.
As shown in graph
901
, anisotropy field lowers as temperature rises.
However, when a conventional magnetic layer was used, as shown in graph
902
, activation magnetic moment visb rises. Activation magnetic moment is known that relates to noise, if the value of the activation magnetic moment is larger, the value of noise is also larger. On the other hand, with smaller activation magnetic moment value due to smaller magnetic particles, while noise can be reduced, there was a problem of reduction in thermal fluctuation resistance at the operating temperature of the magnetic recording/reproduction apparatus.
BRIEF SUMMARY OF THE INVENTION
The purpose of the present invention is to solve the problems described above, and to provide magnetic recording media with good thermal fluctuation resistance and little noise.
Another purpose of the present invention is to provide a magnetic recording/reproduction apparatus capable of magnetic recording and reproduction with good thermal fluctuation resistance and little noise.
The present invention first provides a magnetic recording medium applied to a magnetic recording/reproduction apparatus that carries out recording while heating the recording region to a determined temperature higher than the operation temperature of the magnetic recording/reproduction apparatus, comprising, a substrate, and a magnetic layer essentially consisting of a first magnetic material having a first Curie point higher than the recording temperature, and a second magnetic material having a second Curie point higher than the operation temperature and lower than the recording temperature.
The present invention secondly provides a magnetic recording medium applied to a magnetic recording/reproduction apparatus that carries out recording while heating the recording region to a determined temperature higher than the operation temperature of the magnetic recording/reproduction apparatus, wherein a substrate, and a magnetic layer essentially consisting of a ferromagnetic material having a Curie point higher than the recording temperature, and an antiferromagnetic material having a Neel temperature lower than the recording temperature.
The present invention thirdly provides a magnetic recording/reproduction apparatus comprising a magnetic recording medium, a driving means for holding and rotating the magnetic recording medium, a magnetic head device for recording information onto the magnetic recording medium, a device for reproducing the recorded magnetic information, a recording region heating means for heating the recording region of the magnetic recording medium to a determined recording temperature, and a carriage assembly for holding the magnetic recording head against the magnetic recording medium with freedom of movement, wherein the magnetic recording medium having a substrate and a magnetic layer provided on the substrate and essentially consisting of a first magnetic material with the first Curie point lower than the recording temperature and a second magnetic material with the second Curie point higher than the recording temperature.
The present invention fourthly provides a magnetic recording apparatus, which is a magnetic recording/reproduction apparatus equipped with a magnetic recording medium, a driving means for holding and rotating the magnetic recording medium, a magnetic head device for recording information onto the magnetic recording medium, a device for reproducing the recorded magnetic information, a recording region heating means for heating the recording region of the magnetic recording medium to a determined recording temperature, and a carriage assembly for holding the magnetic recording head against the magnetic recording medium with freedom of movement, wherein the magnetic recording medium having a substrate and a magnetic layer provided on the substrate and essentially consisting of a ferromagnetic material with a Curie point higher than the recording temperature and an antiferromagnetic material with a Neel temperature lower than the recording temperature.
By using the present invention, magnetic recording with good thermal fluctuation resistance and little noise can be realized.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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IBM Technical Disclosure Bulletin, Magnetic Memory Device Utilizing Coupled Film, Jul. 1967, IBM, vol. 10 Issue 2, pp. 144-145.
Hikosaka Takashi
Nakamura Futoshi
Ogiwara Hideo
Oikawa Soichi
Colon Rocio
Gray Cary Ware & Freidenrich LLP
Hudspeth David
Kabushiki Kaisha Toshiba
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