JPH0462140B2 - - Google Patents
Info
- Publication number
- JPH0462140B2 JPH0462140B2 JP16970982A JP16970982A JPH0462140B2 JP H0462140 B2 JPH0462140 B2 JP H0462140B2 JP 16970982 A JP16970982 A JP 16970982A JP 16970982 A JP16970982 A JP 16970982A JP H0462140 B2 JPH0462140 B2 JP H0462140B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- film
- rare earth
- thickness
- transition metal
- 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.)
- Expired - Lifetime
Links
- 239000010409 thin film Substances 0.000 claims description 42
- 239000010408 film Substances 0.000 claims description 39
- 229910045601 alloy Inorganic materials 0.000 claims description 15
- 239000000956 alloy Substances 0.000 claims description 15
- 229910052723 transition metal Inorganic materials 0.000 claims description 14
- 239000000758 substrate Substances 0.000 claims description 5
- 238000002834 transmittance Methods 0.000 claims description 5
- 239000010410 layer Substances 0.000 description 17
- 230000000694 effects Effects 0.000 description 9
- 239000000203 mixture Substances 0.000 description 7
- 230000001681 protective effect Effects 0.000 description 5
- 230000005374 Kerr effect Effects 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 230000005421 thermomagnetic effect Effects 0.000 description 1
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
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イスクの記録媒体としては
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、フア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
することによつて得られる。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ため単層構造では
Ｓ／Ｎ比を上げることが困難である。そこで、
Ｓ／Ｎ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56−156943号、特
開昭57−12428号など）。即ち、光磁気記録媒体薄
膜上にSio，CeO2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，Al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アラデー効果の相乗作
用によつてＳ／Ｎ比を上げる方法などが知られて
いる。しかしながら、従来の高屈折率透明薄膜層
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／Ｎ比の大きな増加
は望み得なかつた。また、Cuなどの反射層を用
いる記録媒体では磁性層のフアラデー効果を主に
利用するものであるが、フアラデー効果による回
転角の増加は磁性層の膜厚によつて制限を受ける
ため充分大きなみかけのカー回転角を得ることが
できなかつた。そこで、本発明者等は反射膜構造
の光磁気記録媒体において反射膜に記録媒体と同
じ材料を用い、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
のキユリー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ツト径の大きさに
違いが生じ（記録層のビツト径大）、記録密度の
低下を生じることが考えられる。 Magneto-optical recording materials are available as recording media for rewritable optical discs. 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 information readout, and in particular, in the Kerr effect method, which uses reflected light from the magneto-optical recording medium to reproduce information, Kerr rotation Since the angle is small, it is difficult to increase the S/N ratio with a single layer structure. Therefore,
Various multilayer structures have been considered as a measure to increase the S/N ratio (for example, Japanese Patent Application Laid-open Nos. 156943-1982 and 12428-1980). That is, a method of increasing the Kerr rotation angle by providing a high refractive index transparent thin film layer such as Sio or CeO 2 on a magneto-optical recording medium thin film;
In addition, a reflective film made of Au, Ag, Cu, Al, etc. is provided on the back side of the recording medium thin film to reflect and utilize not only the reflected light from the medium surface but also the transmitted light that passes through the recording medium. A method of increasing the S/N ratio through the synergistic effect of the Faraday effect is known. However, in the conventional method of providing a transparent thin film layer with a high refractive index, the thickness of the transparent thin film, which increases the Kerr effect, reduces the reflectance, and a large increase in the S/N ratio cannot be expected. In addition, recording media that use reflective layers such as Cu mainly utilize the Faraday effect of the magnetic layer, but the increase in rotation angle due to the Faraday effect is limited by the thickness of the magnetic layer, so the apparent increase in the rotation angle is limited by the thickness of the magnetic layer. It was not possible to obtain the Kerr rotation angle. Therefore, the present inventors used the same material as the recording medium for the reflective film in a magneto-optical recording medium with a reflective film structure, and used the Kerr effect on the surface of the reflective film to increase the apparent Kerr rotation angle when reading information. It was previously proposed to improve the S/N ratio by making it possible to improve the signal-to-noise ratio. In this case, information is recorded on the recording layer and the reflective layer at the same time, but if the Curie temperatures of both are the same, the effect of writing information will be different because there is a difference in the film thickness of the recording layer and the reflective layer. It is conceivable that there is a difference in the recording bit diameter between the recording layer and the reflective layer (the recording layer has a larger bit diameter), resulting in a decrease in recording density.
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、透過膜のキユリー
温度を反射膜のキユリー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ツト
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 Kyrie temperature of the transmission film higher than that of the reflection film, in other words, the recording bit diameter of both films when writing information can be reduced. We have found that this objective can be achieved by keeping the values 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
膜厚の非晶質希土類−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
キユリー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ユリー温
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 rare earth-transition metal alloy thin film having a film thickness that has sufficient transmittance for light, the amorphous rare earth-transition metal alloy has 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 that of the amorphous rare earth-transition metal alloy thin film having the above-mentioned thickness and sufficient reflectance.
通常、光磁気記録を行うにはその記録パワーが
小さくなるようにする必要があり、そのためには
上記透明薄膜層の厚さは薄い方が好ましい。ま
た、本発明においてはこのように小さい記録パワ
ーで記録するために２つの磁性層がともに非晶質
希土類−遷移金属合金である必要がある。しかし
ながら、光磁気記録特性としてカー回転角が十分
大きいことが必要であるため２つの磁性層が具体
的に同一の元素からなる材料である必要はない。 Normally, in order to perform magneto-optical recording, it is necessary to reduce the recording power, and for this purpose, it is preferable that the thickness of the transparent thin film layer is thin. Further, in the present invention, both of the two magnetic layers must be made of an amorphous rare earth-transition metal alloy in order to record with such a small recording power. However, since it is necessary for the magneto-optical recording property that the Kerr rotation angle be sufficiently large, it is not necessary that the two magnetic layers be made of materials specifically made of the same element.
以下、本発明を実施例を示す添付図面によつて
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TbFe，
GdTbFe，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SiO2などの透明薄膜３を形成し、該透明薄
膜３の上面に充分な透過率を有ししかもキユリー
温度が上記の薄膜２よりも高いTbFe，GdTbFe，
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。 FIG. 1 is a sectional view showing an embodiment of the magneto-optical recording medium of the present invention.
An amorphous rare earth-transition metal alloy thin film 2 such as GdTbFe, GdDyFe, or DyTbFe is formed, and a transparent thin film 3 such as SiO 2 is formed on the top surface of the thin film 2, and sufficient transmittance is provided on the top surface of the transparent thin film 3. TbFe, GdTbFe,
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1000ÅのSiO2薄
膜を用い、非晶質希土類−遷移金属合金薄膜４と
して、キユリー温度190℃、膜厚が約500Åの
GdTbFe膜、同じく薄膜２として、キユリー温度
150℃、膜厚が1500ÅのGdTbFe膜を用い、透明
薄膜３として約100ÅのSiO2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度へ増加した。この時He−Neレーザ
光による書き込みビツト径は約1.5μmであり、薄
膜２と薄膜４に同じキユリー温度150℃の
GdTbFe膜を用いた時の書き込みビツト径約3μm
よりも小さいビツト径の書き込みが可能となつ
た。 For example, a SiO 2 thin film with a thickness of about 1000 Å is used as the protective film 5, and a SiO 2 thin film with a thickness of about 500 Å is used as the amorphous rare earth-transition metal alloy thin film 4 at a Curie temperature of 190°C.
GdTbFe film, also as thin film 2, the Curie temperature
When a GdTbFe film with a film thickness of 1500 Å is used at 150°C and a SiO 2 film with a thickness of about 100 Å is used as the transparent thin film 3, the Kerr rotation angle is 0.15 due to the provision of the alloy thin film 2.
degree to 0.62 degree. At this time, the writing bit diameter by the He-Ne laser beam was approximately 1.5 μm, and the same Curie temperature of 150°C was applied to thin films 2 and 4.
Writing bit diameter approximately 3μm when using GdTbFe film
It became possible to write with a bit diameter smaller than that of the previous one.
第３図はGdTbFe膜のキユリー温度と膜組成の
関係をグラフ化したものである。上記の例では、
キユリー温度190℃の膜は希土類の組成が約17％
であり、キユリー温度150℃の膜は希土類の組成
は約12％となる。 Figure 3 is a graph showing the relationship between the Curie temperature and film composition of a GdTbFe film. In the above example,
The film with a Kyrie temperature of 190°C has a rare earth composition of approximately 17%.
Therefore, a film with a Curie temperature of 150°C has a rare earth composition of approximately 12%.
また、別の例として、薄膜４としてキユリー温
度180℃、膜厚が約500ÅのGdTbFe膜、また薄膜
２としてキユリー温度120℃、膜厚が1500Åの
TbFe膜を用いた場合でも、カー回転角は約3.5倍
の増加を示し、ビツト径は約2μmとなつた。 As another example, thin film 4 is a GdTbFe film with a Curie temperature of 180°C and a film thickness of approximately 500 Å, and thin film 2 is a GdTbFe film with a Curie temperature of 120°C and a film thickness of 1500 Å.
Even when the TbFe film was used, the Kerr rotation angle increased by about 3.5 times, and the bit diameter became about 2 μm.
第４図はGdFe膜、GdTbFe膜、TbFe膜のキユ
リー温度と膜組成をグラフ化したものである。上
記の例ではGdTbFe膜の組成はGd20％、Tb8％、
Fe72％であり、TbFe膜の組成はTb28％、Fe72
％である。 FIG. 4 is a graph showing the Curie temperature and film composition of GdFe film, GdTbFe film, and TbFe film. In the above example, the composition of the GdTbFe film is Gd20%, Tb8%,
Fe72%, and the composition of TbFe film is Tb28%, Fe72
%.
また、第１図に示したように、保護膜として
SiO，CeO2等の高屈折率透明膜を用いれば、本
発明によるＳ／Ｎ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 Figure 1, it can be used as a protective film.
If a high refractive index transparent film such as SiO or CeO 2 is used, the effect of increasing the S/N ratio according to the present invention and the S/N ratio due to the transparent film can be improved.
It is also possible to aim for a synergistic effect with the effect of increasing the N ratio.
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
を有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３の上面に充分な反射率を有し、しかもキ
ユリー温度が上記薄膜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。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3.5倍に
増加し、ビツト径は約１〜2μmとなつた。 FIG. 2 is a sectional view showing another embodiment, in which an amorphous rare earth-transition metal alloy thin film 4 having a sufficient transmittance is formed on the upper surface of a substrate 1 made of glass, synthetic resin, etc. Forming a transparent thin film 3 on the thin film 4,
An amorphous rare earth-transition metal alloy thin film 2 having sufficient reflectance and a lower Curie temperature than the thin film 4 is formed on the upper surface of the thin film 3, and a protective film 5 is formed on the thin film 2. There is. In this case, information is recorded and reproduced from the substrate 1 side. In this case as well, the Kerr rotation angle increased by about 3.5 times by providing the thin film 2, and the bit diameter became 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／Ｎ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
奏される。 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 significantly improve the S/N ratio, and information can be obtained. A unique effect is achieved in that it is possible to prevent a decrease in recording density during writing.
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３
図および第４図は膜組成とキユリー温度との関係
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、３……透明薄膜、５……保護膜。
1 and 2 are cross-sectional views showing an example of the structure of the magneto-optical recording medium of the present invention, and FIG.
The figure and FIG. 4 are graphs showing the relationship between film composition and Curie temperature. 1... Substrate, 2, 4... Amorphous rare earth-transition metal alloy thin film, 3... Transparent thin film, 5... Protective film.
Claims (1)
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
膜のキユリー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ユリ
ー温度よりも高いことを特徴とする、光磁気記録
媒体。1 A thin amorphous rare earth-transition metal alloy thin film with a thickness sufficient to reflect light for information reproduction by sandwiching a transparent thin film layer on a substrate, and a thin film having sufficient transmittance to the above light. an amorphous rare earth-transition metal alloy thin film having a thickness of 1. A magneto-optical recording medium 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 JPS5960745A (en) | 1984-04-06 |
| JPH0462140B2 true 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) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH061564B2 (en) * | 1984-02-22 | 1994-01-05 | 株式会社ニコン | Magneto-optical 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 |
-
1982
- 1982-09-30 JP JP16970982A patent/JPS5960745A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5960745A (en) | 1984-04-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4786559A (en) | Magnetooptical storage element | |
| JPH02240845A (en) | Magneto-optical disk | |
| WO1990011602A1 (en) | Magnetooptical medium | |
| JPH0462140B2 (en) | ||
| JPH0263262B2 (en) | ||
| JPH02779B2 (en) | ||
| JPS5960746A (en) | Photomagnetic recording medium | |
| JP2685888B2 (en) | Magneto-optical recording medium | |
| JPS6314342A (en) | Magneto-optical recording medium | |
| JPH039546B2 (en) | ||
| JP2622206B2 (en) | Magneto-optical recording medium | |
| JPS6126954A (en) | Photomagnetic recording medium | |
| EP0661700A1 (en) | Use of a quasi-amorphous or amorphous zirconia dielectric layer for optical or magneto-optic data storage media | |
| JPH0215929B2 (en) | ||
| KR930004332B1 (en) | Optical magnetic recording material | |
| JPS5956241A (en) | Photomagnetic recording medium | |
| JPH0524571B2 (en) | ||
| JPH0458662B2 (en) | ||
| JPS61208650A (en) | Photomagnetic recording medium | |
| JP2562219B2 (en) | Magneto-optical disk | |
| JPS60209946A (en) | Optomagnetic recording medium | |
| JPH08241542A (en) | Optical recording medium | |
| JPS6314344A (en) | Information recording medium | |
| JPH039544B2 (en) | ||
| JPH03165350A (en) | Magneto-optical recording medium |