JPH0714226A - Magneto-optical recording medium - Google Patents
Magneto-optical recording mediumInfo
- Publication number
- JPH0714226A JPH0714226A JP15651593A JP15651593A JPH0714226A JP H0714226 A JPH0714226 A JP H0714226A JP 15651593 A JP15651593 A JP 15651593A JP 15651593 A JP15651593 A JP 15651593A JP H0714226 A JPH0714226 A JP H0714226A
- Authority
- JP
- Japan
- Prior art keywords
- film
- magneto
- magnetic film
- recording medium
- optical recording
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明はレーザ光の照射による温
度上昇を利用して信号の記録・消去を行い、磁気光学効
果を利用して信号の再生を行う光磁気記録媒体に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording / erasing a signal by utilizing a temperature rise caused by laser light irradiation and reproducing a signal by utilizing a magneto-optical effect.
【0002】[0002]
【従来の技術】光磁気記録媒体はメモリとしての応用分
野を拡大するために、データの転送速度を向上させるこ
とが重要である。このため、特開平2−247846号
公報に示すように、光磁気記録媒体そのものの記録感度
を向上させることが知られている。2. Description of the Related Art It is important for a magneto-optical recording medium to improve the data transfer rate in order to expand its application field as a memory. Therefore, it is known to improve the recording sensitivity of the magneto-optical recording medium itself, as disclosed in Japanese Patent Laid-Open No. 2-247846.
【0003】光磁気記録媒体への記録は、レーザ光照射
により記録膜を局部的に補償温度以上の保磁力の小さい
温度、もしくはキューリ温度以上に加熱し、照射部の記
録膜を外部磁界の向きに磁化させることによって行う
(熱磁気記録)。また、その記録信号の再生は、記録消
去時のレーザパワーより低いパワーのレーザ光照射によ
り記録膜の記録状態(磁化の向き)に応じて反射光ある
いは透過光の偏光面が回転する状況を検出することによ
って行う。従来の記録方式には、一定強度のレーザ光を
照射して記録膜の温度を上昇させ、記録信号に応じて向
きの変調された外部磁界で熱磁気記録する方式(磁界変
調記録方式)、および一定強度の外部磁界のもとで記録
信号に応じて強度の変調されたレーザ光を照射して記録
膜の温度を局部的に上昇させて熱磁気記録する方式(光
変調記録方式)がある。Recording on a magneto-optical recording medium is carried out by locally irradiating a laser beam to a temperature having a small coercive force higher than the compensation temperature or a Curie temperature to irradiate the recording film in the irradiated portion with an external magnetic field. It is performed by magnetizing (thermomagnetic recording). In addition, the reproduction of the recording signal detects the situation in which the polarization plane of the reflected light or the transmitted light rotates depending on the recording state (magnetization direction) of the recording film by irradiation with laser light having a power lower than the laser power at the time of recording / erasing. By doing. A conventional recording method is a method of irradiating a laser beam of a constant intensity to raise the temperature of a recording film and performing thermomagnetic recording with an external magnetic field whose direction is modulated according to a recording signal (magnetic field modulation recording method), and There is a system (optical modulation recording system) of irradiating a laser beam whose intensity is modulated according to a recording signal under an external magnetic field of a constant intensity to locally raise the temperature of a recording film and performing thermomagnetic recording.
【0004】図4に従来の光磁気ディスクの構成の一例
を示す。図4において、11はガラス,プラスチックな
どの基板、12および13はZnSe膜からなる保護
膜、14はTbFeCo膜からなる記録膜である。光磁
気記録媒体の記録膜には、高密度記録を行うために垂直
磁気異方性を有するTbFeCo膜等の希土類金属−遷
移金属系合金膜が磁性材料に用いられ、この記録膜の酸
化を防ぐために、ZnSe等の誘電体膜で保護された構
成となっている。FIG. 4 shows an example of the structure of a conventional magneto-optical disk. In FIG. 4, 11 is a substrate made of glass or plastic, 12 and 13 are protective films made of a ZnSe film, and 14 is a recording film made of a TbFeCo film. For the recording film of the magneto-optical recording medium, a rare earth metal-transition metal alloy film such as a TbFeCo film having perpendicular magnetic anisotropy is used as a magnetic material for high density recording, and oxidation of this recording film is prevented. For protection, it is protected by a dielectric film such as ZnSe.
【0005】[0005]
【発明が解決しようとする課題】しかし、上記のような
従来の光磁気記録媒体は、記録ビットが再生光の大きさ
よりも小さくなると前後の記録ビットからの干渉により
再生信号が小さくなるためにS/Nが低下し、高密度記
録が実現できないという課題を有していた。また、記録
トラック間が再生光の大きさよりも狭くすると、近接ト
ラックからのクロストークが増加し再生ジッターとなる
ために、大容量化の妨げとなっていた。However, in the conventional magneto-optical recording medium as described above, when the recording bit becomes smaller than the size of the reproduction light, the reproduction signal becomes small due to the interference from the recording bits before and after S. There is a problem that / N decreases and high density recording cannot be realized. Further, if the distance between the recording tracks is smaller than the size of the reproducing light, crosstalk from the adjacent tracks increases and reproduction jitter occurs, which hinders the increase in capacity.
【0006】本発明は上記課題を解決するもので、記録
ビットの波形干渉および近接トラックからのクロストー
クを低減し、大容量かつ高転送レートの記録再生を可能
にする光磁気記録媒体を提供することを目的としてい
る。The present invention solves the above-mentioned problems, and provides a magneto-optical recording medium capable of recording / reproducing with a large capacity and a high transfer rate by reducing waveform interference of recording bits and crosstalk from adjacent tracks. Is intended.
【0007】[0007]
【課題を解決するための手段】上記目的を達成するため
に、本発明の光磁気記録媒体は、記録膜を光入射側から
第1磁性膜,第2磁性膜の2層の磁性膜で構成し、前記
第1磁性膜は垂直磁化膜であり、前記第2磁性膜は再生
光の照射による温度上昇部でキューリ温度となる面内磁
化膜であり、前記第1磁性膜と前記第2磁性膜の間に交
換結合力が作用している構成を備えたものである。In order to achieve the above object, the magneto-optical recording medium of the present invention comprises a recording film composed of two magnetic films, a first magnetic film and a second magnetic film from the light incident side. The first magnetic film is a perpendicular magnetic film, the second magnetic film is an in-plane magnetic film that has a Curie temperature at a temperature rising portion due to the irradiation of the reproducing light, and the first magnetic film and the second magnetic film. It has a structure in which an exchange coupling force acts between the membranes.
【0008】[0008]
【作用】本発明は上記した構成において、第1磁性膜と
第2磁性膜の間に交換結合力が作用している構成とした
ため、第2磁性膜がキューリ温度以上の領域では、第2
磁性膜からの交換結合力が消失し、第1磁性膜を面内方
向に向ける力はなくなり、第1磁性膜の磁化方向は垂直
となる。このためにこの領域の第1磁性膜からのカー回
転角は増大することになり、第1磁性膜の磁化の情報を
強調して再生信号として読み出すことができることにな
る。According to the present invention, the exchange coupling force acts between the first magnetic film and the second magnetic film in the above-described structure, so that the second magnetic film is not affected by the second magnetic film in the region above the Curie temperature.
The exchange coupling force from the magnetic film disappears, the force for directing the first magnetic film in the in-plane direction disappears, and the magnetization direction of the first magnetic film becomes perpendicular. For this reason, the Kerr rotation angle from the first magnetic film in this region is increased, and the information on the magnetization of the first magnetic film can be emphasized and read as a reproduction signal.
【0009】[0009]
【実施例】以下、本発明の一実施例の光磁気記録媒体に
ついて、図1〜図3を参照しながら説明する。図1は、
本発明の一実施例の光磁気記録媒体の構成を示す。図1
において、1は再生光、2は基板でガラスもしくはプラ
スチックなどからなる。3は第1磁性膜でTbGdFe
Co膜からなり、4は第2磁性膜でTbFe膜からな
り、5および6は保護膜でZnSe膜からなる。前記基
板2上の各膜はスパッタリング法により形成している。DESCRIPTION OF THE PREFERRED EMBODIMENTS A magneto-optical recording medium according to an embodiment of the present invention will be described below with reference to FIGS. Figure 1
1 shows a configuration of a magneto-optical recording medium according to an embodiment of the present invention. Figure 1
In the figure, 1 is reproduction light, and 2 is a substrate made of glass or plastic. 3 is a first magnetic film, TbGdFe
Co film, 4 is a second magnetic film made of TbFe film, and 5 and 6 are protective films made of ZnSe film. Each film on the substrate 2 is formed by a sputtering method.
【0010】上記構成において動作を説明する。図2は
本発明の光磁気記録媒体の磁化状態を示す図である。図
2において、各磁性膜の磁化の方向を矢印で示す。第1
磁性膜3には、光変調方式もしくは磁界変調方式等で情
報が磁化の方向として記録されているものとする。光磁
気記録媒体の再生時には、再生光1の照射により第1磁
性膜3および第2磁性膜4の温度が上昇する。この再生
光照射部の温度でキューリ温度となる面内磁化膜で第2
磁性膜4が構成されているので、第2磁性膜4の温度が
キューリ温度以上になった領域(図2の網目部)では第
2磁性膜4の磁化が消失するために第2磁性膜4からの
交換結合力が働かない。第2磁性膜4がキューリ温度以
下の領域では、第2磁性膜4からの交換結合力により第
1磁性膜3の磁化方向は面内方向に傾くためにこの領域
の第1磁性膜3からのカー回転角は減少する。また、第
2磁性膜4がキューリ温度以上の領域では、第2磁性膜
4からの交換結合力が消失し、第1磁性膜3を面内方向
に向ける力はなくなり、第1磁性膜3の磁化方向は垂直
となる。このためにこの領域の第1磁性膜3からのカー
回転角は増大する。つまり上記構成にすることにより、
再生光1の中心部分の温度上昇領域にある第1磁性膜3
の磁化の情報を強調して再生信号として読み出すことが
できることになる。これは、再生時の再生光1の大きさ
を等価的に小さくしたことに相当し、これによって再生
光1の大きさよりも小さな記録ビットを、前後の記録ビ
ットの波形干渉なしで読み出せることになる。この原理
は、再生ビームの走行方向および走行方向に垂直な方向
にも同様に働くために、波形干渉による再生信号のS/
N低下ならびに近接トラックからのクロストークを減少
させることができる。The operation of the above configuration will be described. FIG. 2 is a diagram showing the magnetization state of the magneto-optical recording medium of the present invention. In FIG. 2, the direction of magnetization of each magnetic film is indicated by an arrow. First
Information is recorded on the magnetic film 3 in the direction of magnetization by an optical modulation method or a magnetic field modulation method. When reproducing the magneto-optical recording medium, the temperature of the first magnetic film 3 and the second magnetic film 4 rises due to the irradiation of the reproducing light 1. The in-plane magnetized film, which has a Curie temperature at the temperature of the reproducing light irradiation section,
Since the magnetic film 4 is formed, the magnetization of the second magnetic film 4 disappears in the region where the temperature of the second magnetic film 4 is equal to or higher than the Curie temperature (mesh portion in FIG. 2), and thus the second magnetic film 4 is removed. The exchange coupling force from does not work. In the region where the second magnetic film 4 is below the Curie temperature, the magnetization direction of the first magnetic film 3 tilts in the in-plane direction due to the exchange coupling force from the second magnetic film 4, so that the region from the first magnetic film 3 in this region is inclined. The car rotation angle decreases. Further, in a region where the second magnetic film 4 has a Curie temperature or higher, the exchange coupling force from the second magnetic film 4 disappears, the force for directing the first magnetic film 3 in the in-plane direction disappears, and the first magnetic film 3 has a The magnetization direction is perpendicular. Therefore, the Kerr rotation angle from the first magnetic film 3 in this region increases. In other words, with the above configuration,
The first magnetic film 3 in the temperature rising region of the central portion of the reproduction light 1
Therefore, it is possible to emphasize the magnetization information and read it as a reproduction signal. This is equivalent to making the size of the reproducing light beam 1 at the time of reproduction equivalently smaller, and thereby recording bits smaller than the size of the reproducing light beam 1 can be read out without waveform interference of the recording bits before and after. Become. This principle also works in the traveling direction of the reproduction beam and in the direction perpendicular to the traveling direction, so that the S /
N degradation as well as crosstalk from adjacent tracks can be reduced.
【0011】次に各膜厚は第1磁性膜3を40nm、第
2磁性膜4を50nm、保護膜5を80nm、保護膜6
を100nmとした。第2磁性膜4のTbFe膜の組成
は、Tb=50%,Fe=50%で、そのキューリ温度
は130℃であった。また、第1磁性膜3のTbGdF
eCo膜はその組成をTb=7%,Gd=15%,Fe
=69.5%,Co=8.5%とした。Next, the respective film thicknesses are 40 nm for the first magnetic film 3, 50 nm for the second magnetic film 4, 80 nm for the protective film 5, and 6 for the protective film.
Was 100 nm. The composition of the TbFe film of the second magnetic film 4 was Tb = 50% and Fe = 50%, and its Curie temperature was 130 ° C. In addition, the TbGdF of the first magnetic film 3
The composition of the eCo film is Tb = 7%, Gd = 15%, Fe
= 69.5% and Co = 8.5%.
【0012】以上の構成の光磁気記録媒体の再生信号ノ
イズ比(以下CN比と記す)の記録ビット長依存性の測
定を行った。この再生CN比の測定は、記録に磁界変調
記録方式を用い、光磁気記録媒体の移動速度が6m/s
で行った。その結果を図3に示し、本発明の光磁気記録
媒体の記録ビット長とCN比の関係を実線で、従来の光
磁気記録媒体の記録ビット長とCN比の関係を点線で示
す。図3から明らかなように、記録ビット長の短い領域
で従来の光磁気記録媒体よりCN比が高く、本発明の光
磁気記録媒体が高密度記録に有効であると言える。ま
た、本発明の光磁気記録媒体において、トラックピッチ
1.4μmのクロストーク量は、従来の光磁気記録媒体
と比較して13dB低下し、これは狭トラックピッチの
光磁気記録媒体の実現を可能とするものである。The dependence of the reproduction signal noise ratio (hereinafter referred to as the CN ratio) on the recording bit length of the magneto-optical recording medium having the above-mentioned structure was measured. The reproduction CN ratio is measured by using a magnetic field modulation recording method for recording, and the moving speed of the magneto-optical recording medium is 6 m / s.
I went there. The results are shown in FIG. 3, in which the relationship between the recording bit length and the CN ratio of the magneto-optical recording medium of the present invention is shown by a solid line, and the relationship between the recording bit length of the conventional magneto-optical recording medium and the CN ratio is shown by a dotted line. As is clear from FIG. 3, the CN ratio is higher than that of the conventional magneto-optical recording medium in the region where the recording bit length is short, and it can be said that the magneto-optical recording medium of the present invention is effective for high density recording. Further, in the magneto-optical recording medium of the present invention, the crosstalk amount at the track pitch of 1.4 μm is 13 dB lower than that of the conventional magneto-optical recording medium, which makes it possible to realize a magneto-optical recording medium having a narrow track pitch. It is what
【0013】なお、本実施例では第2磁性膜4としてT
bFe膜を用いたが、再生光1の中心部の温度でキュー
リ温度となるような面内磁化膜を用いても同様の効果を
得ることができる。本実施例で用いたTbFe膜もCo
を添加することによりキューリ温度をある程度の範囲で
コントロールすることが可能であるので、再生条件など
により再生時の再生光1の中心部の温度が変化しても、
Coの添加により簡単に最適化を行うことができる。In this embodiment, the second magnetic film 4 is made of T
Although the bFe film is used, the same effect can be obtained by using an in-plane magnetized film having a Curie temperature at the temperature of the central portion of the reproduction light 1. The TbFe film used in this example is also Co
Since it is possible to control the Curie temperature within a certain range by adding, even if the temperature of the central portion of the reproduction light 1 during reproduction changes due to reproduction conditions,
Optimization can be easily performed by adding Co.
【0014】[0014]
【発明の効果】以上の説明から明らかなように本発明の
光磁気記録媒体は、記録ビット長が短い場合のS/N向
上とクロストークの低減が同時に達成され、大容量でか
つ高転送レートの光磁気記録装置の実現を可能とするも
のである。As is apparent from the above description, the magneto-optical recording medium of the present invention achieves both S / N improvement and crosstalk reduction at a short recording bit length, a large capacity and a high transfer rate. This enables the realization of the magneto-optical recording device.
【図1】本発明の一実施例の光磁気記録媒体の断面図FIG. 1 is a sectional view of a magneto-optical recording medium according to an embodiment of the present invention.
【図2】同、光磁気記録媒体の磁化状態を示す図FIG. 2 is a diagram showing a magnetization state of the magneto-optical recording medium.
【図3】本発明の一実施例の光磁気記録媒体および従来
の光磁気記録媒体の再生CN比と記録ビット長の関係を
示す特性図FIG. 3 is a characteristic diagram showing a relationship between a reproduction CN ratio and a recording bit length of a magneto-optical recording medium according to an embodiment of the present invention and a conventional magneto-optical recording medium.
【図4】従来の光磁気記録媒体の断面図FIG. 4 is a sectional view of a conventional magneto-optical recording medium.
1 再生光 3 第1磁性膜 4 第2磁性膜 1 reproducing light 3 first magnetic film 4 second magnetic film
Claims (1)
磁性膜の2層の磁性膜で構成し、前記第1磁性膜は垂直
磁化膜であり、前記第2磁性膜は再生光の照射による温
度上昇部でキューリ温度となる面内磁化膜であり、前記
第1磁性膜と前記第2磁性膜の間に交換結合力が作用し
ている構成とした光磁気記録媒体。1. A recording film is provided with a first magnetic film and a second magnetic film from the light incident side.
The first magnetic film is a perpendicular magnetization film, and the second magnetic film is an in-plane magnetization film that has a Curie temperature at a temperature rising portion due to irradiation of reproduction light. A magneto-optical recording medium in which an exchange coupling force acts between the first magnetic film and the second magnetic film.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15651593A JP3220772B2 (en) | 1993-06-28 | 1993-06-28 | Magneto-optical recording medium and reproducing method of the magneto-optical recording medium |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15651593A JP3220772B2 (en) | 1993-06-28 | 1993-06-28 | Magneto-optical recording medium and reproducing method of the magneto-optical recording medium |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2001120422A Division JP2001351281A (en) | 2001-04-19 | 2001-04-19 | Reproduction method for magneto-optical recording medium and the magneto-optical recording medium |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0714226A true JPH0714226A (en) | 1995-01-17 |
JP3220772B2 JP3220772B2 (en) | 2001-10-22 |
Family
ID=15629468
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP15651593A Expired - Fee Related JP3220772B2 (en) | 1993-06-28 | 1993-06-28 | Magneto-optical recording medium and reproducing method of the magneto-optical recording medium |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3220772B2 (en) |
-
1993
- 1993-06-28 JP JP15651593A patent/JP3220772B2/en not_active Expired - Fee Related
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JP3220772B2 (en) | 2001-10-22 |
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