JPS5960745A - Photomagnetic recording medium - Google Patents
Photomagnetic recording mediumInfo
- Publication number
- JPS5960745A JPS5960745A JP16970982A JP16970982A JPS5960745A JP S5960745 A JPS5960745 A JP S5960745A JP 16970982 A JP16970982 A JP 16970982A JP 16970982 A JP16970982 A JP 16970982A JP S5960745 A JPS5960745 A JP S5960745A
- Authority
- JP
- Japan
- Prior art keywords
- film
- thin film
- rare earth
- transition metal
- metal alloy
- 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
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
- G11B11/10586—Record carriers characterised by the selection of the material or by the structure or form characterised by the selection of the material
Abstract
Description
【発明の詳細な説明】
本発明は反射光を用いて情報の再生を行なう光磁気記録
媒体に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical recording medium that reproduces information using reflected light.
書き替え可能な光ディスクの記録媒体とじては光磁気記
録材料がある。この材料は情報の書き込みには熱磁気効
果を用い、読み出しには磁気カー効果、ファラデー効果
などの磁気光学効果を利用する。すなわち、磁気情報は
、直線偏光の光ビームが記録媒体に貯えられている磁気
情報との相互作用を受けた後の反射光の偏光方向の回転
を検出することによって得られる。しかし、現在の光磁
気記録媒体は情報の読み出しＳ／′Ｎ比が低いという欠
点を有し、特に光磁気記録媒体からの反射光を利用して
情報の再生を行なうカー効果方式においては、カー回転
角が小さいだめ単層構造ではｓ／１比を上げることが困
難である。そこで、い比を上げる方策としては各種の多
層構造が考えられている（例えば特開昭５６−１５６９
４３号、特開昭５７−１２４２８号など）。即ち、光磁
気記録媒体薄膜上に５ｉＯ１Ｃｅ０２などの高屈折率透
明薄膜層を設けることにより、カー回転角を増大させる
方法、また記録媒体薄膜の裏側にＡｕ、 Ａｇ、 Ｃｕ
、 Ａｔなどの反射膜を設けて、媒体表面からの反射光
だけでなく、記録媒体を通過してしまう透過光も反射さ
せて利用しカー効果とファラデー効果の相乗作用によっ
てＳ／Ｎ比を上げる方法などが知られている。Magneto-optical recording materials are examples of rewritable optical disk recording media. This material uses thermomagnetic effects to write information, and uses magneto-optical effects such as the magnetic Kerr effect and Faraday effect to read information. That is, magnetic information is obtained by detecting the rotation of the polarization direction of reflected light after a linearly polarized light beam interacts with magnetic information stored in a recording medium. However, current magneto-optical recording media have the disadvantage of a low S/N ratio for reading information, and in particular, the Kerr effect method, which uses reflected light from the magneto-optical recording medium to reproduce information, Since the rotation angle is small, it is difficult to increase the s/1 ratio with a single layer structure. Therefore, various multilayer structures have been considered as a measure to increase the ratio (for example, Japanese Patent Application Laid-Open No. 56-1569
No. 43, JP-A-57-12428, etc.). That is, there is a method of increasing the Kerr rotation angle by providing a high refractive index transparent thin film layer such as 5iO1Ce02 on the magneto-optical recording medium thin film, and a method of increasing the Kerr rotation angle by providing a high refractive index transparent thin film layer such as 5iO1Ce02 on the magneto-optical recording medium thin film.
, A reflective film such as At is provided to reflect and utilize not only the reflected light from the medium surface but also the transmitted light that passes through the recording medium, increasing the S/N ratio by the synergistic effect of the Kerr effect and Faraday effect. Methods are known.
しかしながら、従来の高屈折率透明薄膜ｊ−を設ける方
式ではカー効果を増加する透明薄膜の膜厚は反射率を減
少させ、Ｓハ比の大きな増加は望み得なかった。また、
Ｃｕなどの反射層を用いる記録媒体では磁性層の７アラ
ダー効果を主に利用するものであるが、ファラデー効果
による回転角の増加は磁性層の膜厚によって制限を受け
るため充分大きなみかけのカー回転角を得ることができ
なかった。そこで、本発明者等は反射膜栴造の光磁気記
録媒体において反射膜に記録媒体と−」じ相料を用い、
情報の読み出し時に、反射膜表面におけるカー効果を利
用して、みかけのカー回転角を増大させ得るようにして
Ｓ／′Ｎ比を改善することを先に提案した。この場合、
記録層と反射層に同時に情報を記録するわけであるが、
この両者のキュリ一温度が同じであると、記録層と反射
層の膜厚に差があるため、情報の書き込み効果が異なり
、記録層と反射層の記録ビット径の大きさに違いが生じ
（記録層のビット径大）、記録密度の低下を生じること
が考えられる。However, in the conventional method of providing a high refractive index transparent thin film j-, the thickness of the transparent thin film, which increases the Kerr effect, reduces the reflectance, and a large increase in the S ratio cannot be expected. Also,
Recording media that use reflective layers such as Cu mainly utilize the 7 Allarder effect of the magnetic layer, but since the increase in rotation angle due to the Faraday effect is limited by the thickness of the magnetic layer, a sufficiently large apparent Kerr rotation is required. Couldn't get the corner. Therefore, the present inventors used the same phase material as the recording medium for the reflective film in the magneto-optical recording medium of Senzo reflective film,
It was previously proposed to improve the S/'N ratio by increasing the apparent Kerr rotation angle by utilizing the Kerr effect on the surface of the reflective film when reading information. in this case,
Information is recorded on the recording layer and reflective layer at the same time.
If the Curie temperature of the two is the same, there will be a difference in the film thickness of the recording layer and the reflective layer, so the information writing effect will be different, and the recording bit diameter of the recording layer and the reflective layer will be different ( If the bit diameter of the recording layer becomes large), the recording density may decrease.
そこで、本発明者等は記録密度の低下を防止すべくさら
に改良を重ねた結果、透過膜のキュリ一温度を反射膜の
キュリ一温度よりも高くすることによりつまり情報書き
込み時の両膜の記録ビット径を同程度に保つことにより
その目的を達成できることを見出した。Therefore, the present inventors made further improvements in order to prevent the decrease in recording density, and as a result, by making the Curie temperature of the transmission film higher than the Curie temperature of the reflection film, in other words, the recording of both films during information writing is possible. We have found that this objective can be achieved by keeping the bit diameters at the same level.
本発明の光磁気記録媒体は、基板上に透明薄膜層をはさ
んで、情報再生用の光に対して充分な反射率を有する膜
厚の非晶質希土類−遷移金属合金薄膜と、上記の光に対
して充分な透過率を有する膜厚の非晶η希土類−遷移金
属合金薄膜を設けた光磁気記録媒体において、上記の充
分な透過率を有する膜厚の非晶質希土類−遷移金属合金
薄膜のキュリ一温度が上記の充分な反射率を有する膜厚
の非晶質希土類−遷移金属合金薄膜のキュリ一温度より
も高いことを特徴とするものである。The magneto-optical recording medium of the present invention comprises a transparent thin film layer sandwiched between substrates, an amorphous rare earth-transition metal alloy thin film having a thickness sufficient to reflect light for information reproduction, and the above-mentioned thin film. In a magneto-optical recording medium provided with an amorphous η rare earth-transition metal alloy thin film having a film thickness that has sufficient transmittance for light, an amorphous rare earth-transition metal alloy having a film thickness that has the above-mentioned sufficient transmittance. The present invention is characterized in that the Curie temperature of the thin film is higher than the Curie temperature of the amorphous rare earth-transition metal alloy thin film having the above-mentioned thickness and sufficient reflectance.
以下、本発明を実施例を示す添付図面によって詳細に説
明する。Hereinafter, the present invention will be explained in detail with reference to the accompanying drawings showing examples.
第１図は、本発明の光磁気記録媒体の一実施例を示す断
面図であり、ガラス、合成樹脂などの基板１の上面に、
充分な反射率を有するＴｂＦ’ｅ、Ｇｄ’ｌ’ｂＦｅ、
ＧｄＤｙＦｅ、 ＤｙＴｂＦｅなどの非晶質希土類−
遷移金属合金薄膜２を形成し、該薄膜２の上面に８１０
２などの透明薄膜３を形成し、該透明薄膜層の上面に充
分な透過率を鳴ししかもキュリ一温度が上記の薄膜２よ
りも高いＴｂＦｅ、 ＧｄＤｙＦｅ。FIG. 1 is a sectional view showing an embodiment of the magneto-optical recording medium of the present invention.
TbF'e, Gd'l'bFe, with sufficient reflectance;
Amorphous rare earths such as GdDyFe and DyTbFe
A transition metal alloy thin film 2 is formed, and 810
A transparent thin film 3 such as TbFe, GdDyFe, etc. 2 is formed on the upper surface of the transparent thin film layer, and has a sufficient transmittance and a higher Curie temperature than the above thin film 2.
ＧｄＤｙＦｅ、 ＤｙＴｂＦｅなどの非晶質希土類−遷
移金属合金薄膜４を形成し、さらに該薄膜４の上に保護
膜５を形成している。An amorphous rare earth-transition metal alloy thin film 4 such as GdDyFe or DyTbFe is formed, and a protective film 5 is further formed on the thin film 4.
例えば保護膜５として厚さ約ｔ、ｏｏｏＸの５ｉ０２薄
膜を用い、非晶質希土類−遷移金属合金薄膜４として、
キュリ一温度１９０℃、膜厚が約５００Ｘ（７） Ｇｄ
ＴｂＦｅ膜、同じく薄膜２として、キュ４ノ一温反１５
０℃、膜厚が１５００ Ｘ （Ｄ ＧｄＴｂＦｅ ｔｉ
ｊ ヲ用イ、透明薄膜６として約ｔｏｏＸの５ｉｏ２膜
を用いた場合、カー回転角は合金薄膜２を設けたことに
より、０．１５度から０．６２良へ増加した。この時Ｈ
ｅ−Ｎｅレーザ光による書き込みビット径は約１．５μ
ｍであり、薄膜２と薄膜４に同じキュリ一温度１５０℃
のＧｄＴｂＦｅ膜を用いた時の書き込みヒツト径約３μ
ｍよりも小さいビット径の書き込みが可能となった。For example, a 5i02 thin film with a thickness of about t and oooX is used as the protective film 5, and as the amorphous rare earth-transition metal alloy thin film 4,
Curie temperature 190℃, film thickness approximately 500X (7) Gd
TbFe film, also as thin film 2,
0℃, film thickness 1500X (D GdTbFe ti
When a 5io2 film of about tooX was used as the transparent thin film 6, the Kerr rotation angle increased from 0.15 degrees to 0.62 degrees by providing the alloy thin film 2. At this time H
The writing bit diameter by e-Ne laser beam is approximately 1.5μ
m, and the same Curie temperature of 150°C is applied to thin film 2 and thin film 4.
When using a GdTbFe film, the writing hit diameter is approximately 3μ.
It is now possible to write with a bit diameter smaller than m.
第６図に’Ｌ ＧｄＴｂＦｅ膜のキュリ一温度と膜組成
の関係をグラフ化したものである。上記の例では、キュ
リ一温度１９０℃の膜は希土類の組成が約１７チであり
、キュリー温１１ｓｏ℃の膜は希土類の組成は約１２チ
となる。FIG. 6 is a graph showing the relationship between the Curie temperature and the film composition of the 'L GdTbFe film. In the above example, a film having a Curie temperature of 190° C. has a rare earth composition of about 17°, and a film having a Curie temperature of 11° C. has a rare earth composition of about 12°.
また、別の例として、薄膜４としてキュリー温ｆｆ１８
０℃、Ｍ 厚カ約５００ Ｘ （７） ＧｄＴｂＦｅ
膜、マタ薄膜２としてキュリ一温度１２０℃、膜卸が約
１５０ＯＡのＴｂＦｅ膜を用いた場合でも、カー回転角
は約６．５倍の増加を示し、ビット径は約２μｍとなっ
た。In addition, as another example, as the thin film 4, the Curie temperature ff18
0℃, M thickness approx. 500X (7) GdTbFe
Even when a TbFe film with a Curie temperature of 120° C. and a film weight of about 150 OA was used as the thin film 2, the Kerr rotation angle increased by about 6.5 times and the bit diameter became about 2 μm.
第４図はＧｄＦ’ｅ膜、ＧｄＴｂＦｅ膜、ＴｂＦｅ膜の
キュリ一温度と膜組成をグラフ化したものである。FIG. 4 is a graph showing the Curie temperature and film composition of the GdF'e film, GdTbFe film, and TbFe film.
上記の例ではＧｄＴｂＦｅ膜の組成はＧｃｌ、 ２０％
、Ｔｂ ８チ、Ｆ’ｅ７２％であり、ＴｂＦｅ Ｊ＆！
の組成はＴｂ２８％、Ｆｅ７２％である。In the above example, the composition of the GdTbFe film is Gcl, 20%
, Tb 8chi, F'e 72%, and TbFe J&!
The composition is 28% Tb and 72% Fe.
また、第１図に示したように、保護膜としてＳｉｎ、
ＣｅＯ２等の説屈折率透明膜を用いれば、本発明による
Ｓハ比増加効果と透明膜によるＳ／Ｎ比増加効果との相
乗効果を狙うことも可能である。In addition, as shown in FIG. 1, as a protective film,
If a transparent film with a refractive index such as CeO2 is used, it is possible to achieve a synergistic effect between the effect of increasing the S/C ratio according to the present invention and the effect of increasing the S/N ratio due to the transparent film.
第２図は他の実施例を示す断面図であり、ガラス、合成
樹脂などの基板１の上面に充分な透過率を翁する膜厚の
非晶質希土類−遷移金属合金薄膜４を形成し、該薄膜４
上に透明薄膜３を形成し、該薄膜乙の上面に充分な反射
率を有し、しかもキュリ一温度が上記薄膜４よりも低い
非晶質希土類−遷移金属合金薄膜２を形成し、該薄膜２
上に保護膜５を形成している。この場合、情報の記録お
よび再生は基板１側から行なう。FIG. 2 is a sectional view showing another embodiment, in which an amorphous rare earth-transition metal alloy thin film 4 having a thickness that provides sufficient transmittance is formed on the upper surface of a substrate 1 made of glass, synthetic resin, etc. The thin film 4
A transparent thin film 3 is formed thereon, an amorphous rare earth-transition metal alloy thin film 2 having a sufficient reflectance and a Curie temperature lower than that of the thin film 4 is formed on the upper surface of the thin film A; 2
A protective film 5 is formed thereon. In this case, information is recorded and reproduced from the substrate 1 side.
この場合にもカー回転角は薄膜２を設けることにより約
６．５倍に増加し、ビット径は約１〜２μｍとなった。In this case as well, the Kerr rotation angle was increased by about 6.5 times by providing the thin film 2, and the bit diameter was about 1 to 2 μm.
以上のようにして構成された本発明の光磁気記録媒体に
よれば、光磁気記録媒体のカー回転角を増加させてＳ／
ｘｑ比の大幅な向上を図り、得ることができ、また、情
報の書き込み時の記録密度の低下も防止することができ
るという特有の効果が妻される。According to the magneto-optical recording medium of the present invention configured as described above, the Kerr rotation angle of the magneto-optical recording medium can be increased to
It has the unique effect of being able to significantly improve the xq ratio and preventing a decrease in recording density when writing information.
第１図および第２図はそれぞれ本発明の光磁気記録媒体
の構成例を示す断面図でありそして第６図および第４図
は膜組成とキュリ一温度との関係を示すグラフである。
１・・・基板、２，４・・・非晶質希土類−遷移金属合
金薄膜、６・・・透明薄膜、５・・・保護膜。
２２３FIGS. 1 and 2 are cross-sectional views showing examples of the structure of the magneto-optical recording medium of the present invention, and FIGS. 6 and 4 are graphs showing the relationship between film composition and Curie temperature. DESCRIPTION OF SYMBOLS 1... Substrate, 2, 4... Amorphous rare earth-transition metal alloy thin film, 6... Transparent thin film, 5... Protective film. 223
Claims (1)
て充分な反射率を有する膜厚の非晶質希土類−遷移金属
合金薄膜と、上記の光に対して充分な透過率を有する膜
厚の非晶質希土類−遷移金属合金薄膜とを設け、そして
上記の充分な透過率を有する膜厚の非晶質希土類−遷移
金属合金薄膜のキュリ一温度が上記の充分な反射率を有
する膜厚の非晶質希土類−遷移金属合金薄膜のキュリ一
温度よシも高いことを特徴とする、光磁気記録媒体。On the substrate, a transparent thin film layer is sandwiched between an amorphous rare earth-transition metal alloy thin film having a thickness sufficient to reflect light for information reproduction, and a thin film having sufficient transmittance to the above light. and the Curie temperature of the amorphous rare earth-transition metal alloy thin film having the above-mentioned sufficient transmittance has the above-mentioned sufficient reflectance. 1. A magneto-optical recording medium characterized by having a film thickness higher than the Curie temperature of an amorphous rare earth-transition metal alloy thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16970982A JPS5960745A (en) | 1982-09-30 | 1982-09-30 | Photomagnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16970982A JPS5960745A (en) | 1982-09-30 | 1982-09-30 | Photomagnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5960745A true JPS5960745A (en) | 1984-04-06 |
| JPH0462140B2 JPH0462140B2 (en) | 1992-10-05 |
Family
ID=15891409
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16970982A Granted JPS5960745A (en) | 1982-09-30 | 1982-09-30 | Photomagnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5960745A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3638838A1 (en) * | 1986-11-13 | 1988-05-19 | Nicolas Schnur | Recording carrier and process for writing, reading and erasing information in this carrier |
| US5087532A (en) * | 1989-08-01 | 1992-02-11 | Minnesota Mining And Manufacturing Company | Direct-overwrite magneto-optic media |
| US5204193A (en) * | 1984-02-22 | 1993-04-20 | Nippon Kogaku K.K. | Recording magnetooptical recording medium |
-
1982
- 1982-09-30 JP JP16970982A patent/JPS5960745A/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5204193A (en) * | 1984-02-22 | 1993-04-20 | Nippon Kogaku K.K. | Recording magnetooptical recording medium |
| DE3638838A1 (en) * | 1986-11-13 | 1988-05-19 | Nicolas Schnur | Recording carrier and process for writing, reading and erasing information in this carrier |
| US5087532A (en) * | 1989-08-01 | 1992-02-11 | Minnesota Mining And Manufacturing Company | Direct-overwrite magneto-optic media |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0462140B2 (en) | 1992-10-05 |
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