JPH0935342A - Magneto-optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magento-optical recording medium having high sensitivity to a magnetic field and a high C-N ratio in a wide intensity range of an external magnetic field by regulating the compensation temp. of a 2nd magnetic layer to a specified range and the thickness of a 1st magnetic layer to a specified range. SOLUTION: A dielectric layer 2 is formed on a transparent substrate 1 of glass, plastic, etc., and a thin film 3 of an amorphous ferrimagnetic rare earth element-transition metal alloy such as GdFe, GdFeCo, GdCo or GdTbFeCo is laminated. A thin film 4 of an amorphous ferrimagnetic heavy rare earth element-transition metal alloy having high perpendicular anisotropy and high coercive force, e.g., TbFeCo, DyFeCo, TbDyFeCo or DyGdFeCo is then formed. The compensation temp. of the 2nd magnetic layer 3 is regulated to 80-150 deg.C and the thickness of the 1st magnetic layer 4 is regulated to 15-30nm to obtain the objective magneto-optical recording medium having high sensitivity to a magnetic field and a high C-N ratio in a wide intensity range of an external magnetic field.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は集光したレーザー光
と磁界を用いて垂直磁化膜に情報の記録、再生、消去を
行う光磁気記録媒体に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording, reproducing and erasing information on a perpendicular magnetization film by using a focused laser beam and a magnetic field.

【０００２】[0002]

【従来の技術】レーザー光を用いて基板上に設けられた
垂直磁化膜に記録を行う、いわゆる光磁気記録方式は書
き換えが可能で大容量の記録を行う方法として従来より
広く利用されている。現在この光磁気記録媒体の記録膜
に用いられる磁性膜としては膜面に垂直な磁化容易軸を
有する希土類−遷移金属アモルファス合金薄膜が最も多
く用いられている。2. Description of the Related Art A so-called magneto-optical recording method, in which recording is performed on a perpendicularly magnetized film provided on a substrate by using a laser beam, has been widely used as a rewritable and large-capacity recording method. At present, as the magnetic film used for the recording film of this magneto-optical recording medium, a rare earth-transition metal amorphous alloy thin film having an easy axis of magnetization perpendicular to the film surface is most often used.

【０００３】上記の記録膜を用いた光磁気記録方式とし
ては２００〜４００（Ｏｅ）程度の磁界を作用させなが
ら、レーザービームを記録すべきデータに従ってパルス
変調し記録を行う光変調方式が多く用いられている。し
かしこの方式の場合、既に記録が行われている場所に新
たなデータの記録を行おうとすると、一旦、既に記録さ
れているデータの消去を行ってから新しいデータの記録
を行わなければならず、これが光磁気記録媒体のデータ
転送速度向上の障害となっていた。As a magneto-optical recording method using the above recording film, an optical modulation method in which a laser beam is pulse-modulated according to data to be recorded and recording is often used while a magnetic field of about 200 to 400 (Oe) is applied. Has been. However, in the case of this method, when trying to record new data in a place where recording has already been performed, it is necessary to once erase the already recorded data and then record new data. This has been an obstacle to improving the data transfer rate of the magneto-optical recording medium.

【０００４】これに対し、上記光変調方式とは逆に、一
定の強さのレーザービームを連続照射しつつ、外部磁界
の磁界の方向を記録すべきデータに従って高速で変調し
て記録を行う磁界変調方式が知られている。この方式は
旧データが記録されている部分に直接新しいデータの記
録を行うこと（ダイレクト・オーバーライト）ができる
ため、光磁気記録媒体のデーター転送速度を向上させる
方法として近年特に注目されている。On the other hand, contrary to the above-mentioned optical modulation method, while continuously irradiating a laser beam of a constant intensity, the direction of the magnetic field of the external magnetic field is modulated at high speed according to the data to be recorded, and the magnetic field is recorded. A modulation method is known. In this method, since new data can be directly recorded on the portion where old data is recorded (direct overwrite), it has been particularly noted in recent years as a method for improving the data transfer rate of a magneto-optical recording medium.

【０００５】この磁界変調方式の場合、外部磁界を発生
させる電磁石を高速でスイッチングさせなければなら
ず、磁気ヘッドのインダクタンスを小さくする必要があ
る。そのため浮上ヘッド方式に見られるように、小型の
ヘッドを記録層に近接した位置に配置し、これにより記
録を行う方法が一般に用いられるが、その発生磁界は小
さくなるという欠点がある。一方、従来の光変調方式で
は比較的大きな磁界を印加して記録を行うことができる
ため、２００（Ｏｅ）程度の磁界で記録を行うことがで
きる光磁気記録媒体であれば十分であったが、磁界変調
方式に用いられる記録媒体の場合、上記の理由で記録磁
界に対する感度がさらに高い媒体が求められている。In the case of this magnetic field modulation method, the electromagnet for generating the external magnetic field must be switched at high speed, and the inductance of the magnetic head must be reduced. Therefore, as in the flying head system, a method of arranging a small head in a position close to the recording layer and performing recording by this is generally used, but there is a drawback that the generated magnetic field is small. On the other hand, in the conventional optical modulation method, since recording can be performed by applying a relatively large magnetic field, a magneto-optical recording medium capable of recording with a magnetic field of about 200 (Oe) is sufficient. In the case of the recording medium used in the magnetic field modulation method, a medium having a higher sensitivity to the recording magnetic field is required for the above reasons.

【０００６】このような磁界変調方式において、記録、
消去時の磁界を低減させるためには、次のような特性が
求められている。図１は一般的な光磁気記録媒体の記録
特性を示す。これは予め消去方向に磁化の向きを揃えた
媒体に光変調方式で記録を行った場合のＣＮ比の記録磁
界依存性である。ここで負が消去方向、正が記録方向の
磁界である。磁界変調方式での記録、消去磁界を低減さ
せ、かつ高いＣＮ比の記録を行うためには、図における
ＣＮ比が飽和する磁界（飽和磁界、Ｈｓ）と記録が始ま
る磁界（記録開始磁界、Ｈｏ）の絶対値を小さくする必
要がある。具体的には、このＨｏおよびＨｓの絶対値は
２００（Ｏｅ）以下が好ましい。ところが従来より光変
調記録方式に用いられている光磁気記録媒体は、このＨ
ｏとＨｓの絶対値がいずれも大きく、磁界変調方式で高
速にデータの記録を行うためには不十分であった。In such a magnetic field modulation system, recording,
In order to reduce the magnetic field at the time of erasing, the following characteristics are required. FIG. 1 shows the recording characteristics of a general magneto-optical recording medium. This is the recording magnetic field dependence of the CN ratio when recording is performed by an optical modulation method on a medium whose magnetization direction is aligned in advance with the erasing direction. Here, the negative is the magnetic field in the erasing direction and the positive is the magnetic field in the recording direction. In order to reduce the recording / erasing magnetic field in the magnetic field modulation method and to record with a high CN ratio, a magnetic field where the CN ratio is saturated (saturation magnetic field, Hs) and a magnetic field where recording starts (recording start magnetic field, Ho ) It is necessary to reduce the absolute value of. Specifically, the absolute values of Ho and Hs are preferably 200 (Oe) or less. However, the magneto-optical recording medium conventionally used in the optical modulation recording system is
The absolute values of o and Hs are both large, which is insufficient for high-speed data recording by the magnetic field modulation method.

【０００７】この記録、消去時の磁界を低減させるため
に、種々の方法が提案されている。例えば、光磁気記録
媒体の記録膜を構成している誘電体層や磁性層をスパッ
タ法により成膜する際に成膜ガス圧を変化さえたり、逆
スパッタを行う等、成膜条件により高磁界感度化を達成
する方法が知られているが、この方法では記録、消去磁
界を低減しようとすると、再生時のノイズが増加し、そ
の結果ＣＮ比が低下するという欠点があった。Various methods have been proposed to reduce the magnetic field during recording and erasing. For example, when a dielectric layer or a magnetic layer forming a recording film of a magneto-optical recording medium is formed by a sputtering method, the film forming gas pressure is changed, or reverse sputtering is performed. Although a method of achieving high sensitivity has been known, this method has a drawback in that, when an attempt is made to reduce a recording / erasing magnetic field, noise at the time of reproduction increases, and as a result, the CN ratio decreases.

【０００８】一方、磁性層を保磁力が大きくキュリー温
度が比較的低い第１の磁性層と、保磁力が小さくキュリ
ー温度が高い第２の磁性層の２層を磁気的に交換結合さ
せることにより、記録、消去時の磁界を低減する方法
が、例えば特開昭６４−３２４４１号、特開平２−２３
０５３５号、特開平４−７４３２８号、特開平６−４４
６２６号、または特開平６−１０３６２０号公報等で知
られている。しかし、これらに示されているような磁性
層の二層化では微小磁区の形成が不安定であるため高い
ＣＮ比が得られず、特に高密度記録に対応するためには
未だ不十分であった。On the other hand, by magnetically exchange-coupling the two magnetic layers, the first magnetic layer having a large coercive force and a relatively low Curie temperature and the second magnetic layer having a small coercive force and a high Curie temperature. A method for reducing the magnetic field during recording and erasing is disclosed in, for example, JP-A-64-32441 and JP-A-2-23.
0535, JP-A-4-74328, JP-A-6-44
No. 626 or Japanese Patent Laid-Open No. 6-103620. However, in the double-layered magnetic layer as shown in these documents, the formation of minute magnetic domains is unstable, so that a high CN ratio cannot be obtained, which is still insufficient for high density recording. It was

【０００９】これに対し、各々の層のキュリー温度未満
の温度範囲では互いに交換結合している二層からなる磁
性膜で、キュリー温度が比較的高い層がキュリー温度の
比較的低い層のキュリー温度以上で面内磁気異方性を示
すようにすると上記ような欠点を改善し、高いＣＮ比が
得られることが特願平７−９６７６９に記載されてい
る。しかしこの方法の場合、キュリー温度が高い層の組
成の変化によりＨｏ、Ｈｓの値が変化し、組成によって
は磁界変調記録に不適当なＣＮ比の外部磁界依存性を示
す場合もあった。一方、この記録媒体に光変調方式によ
り高密度の記録を行うと、小さな外部磁界で記録を行っ
た場合は高いＣＮ比が得られるものの、比較的大きな外
部磁界で記録を行うとＣＮ比が低下するといった問題が
あった。On the other hand, in a magnetic film composed of two layers exchange-coupled to each other in a temperature range lower than the Curie temperature of each layer, a layer having a relatively high Curie temperature is a Curie temperature of a layer having a relatively low Curie temperature. It is described in Japanese Patent Application No. 7-96769 that the above-mentioned defects can be improved and a high CN ratio can be obtained by exhibiting the in-plane magnetic anisotropy. However, in the case of this method, the values of Ho and Hs change due to the change in the composition of the layer having a high Curie temperature, and depending on the composition, the CN ratio unsuitable for the magnetic field modulation recording may show the external magnetic field dependence. On the other hand, when high density recording is performed on this recording medium by the optical modulation method, a high CN ratio is obtained when recording is performed with a small external magnetic field, but the CN ratio is lowered when recording is performed with a relatively large external magnetic field. There was a problem of doing.

【００１０】[0010]

【発明が解決しようとする課題】本発明の目的は、記
録、消去に必要な外部磁界を低減すると同時に、記録時
の外部磁界が小さい場合から比較的大きい場合まで高い
ＣＮ比が得られ、記録磁界の小さな磁界変調方式でも、
又、比較的記録磁界の大きな光変調方式に於いても良好
な特性で記録を行うことができ、高密度の記録を行うの
に適した光磁気記録媒体を提供することにある。An object of the present invention is to reduce the external magnetic field required for recording and erasing, and at the same time, to obtain a high CN ratio from a small external magnetic field during recording to a relatively large external magnetic field. Even with a magnetic field modulation method with a small magnetic field,
Another object of the present invention is to provide a magneto-optical recording medium which is suitable for high-density recording, because recording can be performed with good characteristics even in an optical modulation system having a relatively large recording magnetic field.

【００１１】[0011]

【課題を解決するための手段】上記目的を達成すべく鋭
意検討を行った結果、本発明に至った。すなわち本発明
の第一は、基板上にフェリ磁性の希土類−遷移金属アモ
ルファス合金を主とする第１の磁性層および第２の磁性
層を有し、第２の磁性層のキュリー温度が第１の磁性層
のキュリー温度より高く、第１の磁性層のキュリー温度
未満の温度範囲において、この第１の磁性層と第２の磁
性層がいずれも垂直磁気異方性を示し、磁気的に交換結
合をしているのに対し、第１の磁性層のキュリー温度以
上、第２の磁性層のキュリー温度未満の温度範囲におい
ては、第２の磁性層が面内磁気異方性を示す光磁気記録
媒体において、第２の磁性層の補償温度が８０℃以上、
１５０℃以下の範囲にあることを特徴とする。さらに、
本発明の第二は、以上の光磁気記録媒体において、第１
の磁性層の膜厚が１５ｎｍ以上、３０ｎｍ以下の範囲に
あることを特徴とするものである。Means for Solving the Problems As a result of intensive studies to achieve the above object, the present invention has been accomplished. That is, a first aspect of the present invention has a first magnetic layer and a second magnetic layer mainly composed of a ferrimagnetic rare earth-transition metal amorphous alloy on a substrate, and the Curie temperature of the second magnetic layer is the first. In the temperature range higher than the Curie temperature of the magnetic layer and lower than the Curie temperature of the first magnetic layer, both the first magnetic layer and the second magnetic layer exhibit perpendicular magnetic anisotropy and are magnetically exchanged. On the other hand, in the temperature range of not less than the Curie temperature of the first magnetic layer and less than the Curie temperature of the second magnetic layer, the second magnetic layer exhibits magneto-optical anisotropy. In the recording medium, the compensation temperature of the second magnetic layer is 80 ° C. or higher,
It is characterized by being in the range of 150 ° C. or lower. further,
A second aspect of the present invention provides the first magneto-optical recording medium as described above.
The film thickness of the magnetic layer is in the range of 15 nm or more and 30 nm or less.

【００１２】この２層よりなる磁性膜の記録メカニズム
を図２に示す。磁性膜にレーザー光を照射すると磁性膜
の照射部分は第１の磁性層のキュリー温度以上にまで加
熱される。この温度において第２の磁性層は面内磁気異
方性を示す。続いて加熱後に第１、第２の磁性層の温度
が第１の磁性層のキュリー温度にまで低下すると、第１
の磁性層に磁化が現れ、外部磁場によりまず第１の磁性
層に記録が行われる。この際、磁気的な交換相互作用に
より第１の磁性層の各副格子磁化の方向が第２の磁性層
に転写されることにより記録が終了する。FIG. 2 shows the recording mechanism of the magnetic film composed of these two layers. When the magnetic film is irradiated with laser light, the irradiated portion of the magnetic film is heated up to the Curie temperature of the first magnetic layer or higher. At this temperature, the second magnetic layer exhibits in-plane magnetic anisotropy. Then, when the temperature of the first and second magnetic layers decreases to the Curie temperature of the first magnetic layer after heating, the first
Magnetization appears in the first magnetic layer, and recording is first performed in the first magnetic layer by the external magnetic field. At this time, recording is completed by transferring the direction of each sub-lattice magnetization of the first magnetic layer to the second magnetic layer by magnetic exchange interaction.

【００１３】このようなメカニズムで記録が行われる光
磁気記録媒体は、従来の交換結合２層磁性膜とは異な
り、まず保磁力および垂直異方性の大きい第１の磁性層
に記録が行われるため、安定な記録ビットが形成され
る。さらにこれがキュリー温度が高く、カー回転角の大
きい第２の磁性層に転写されるという記録過程を経るた
め、再生時に第２の磁性層の側から読み出しを行うと高
いＣＮ比が得られる。In the magneto-optical recording medium in which recording is performed by such a mechanism, unlike the conventional exchange-coupling two-layer magnetic film, recording is first performed in the first magnetic layer having large coercive force and perpendicular anisotropy. Therefore, stable recording bits are formed. Furthermore, since this undergoes a recording process in which it is transferred to the second magnetic layer having a high Curie temperature and a large Kerr rotation angle, a high CN ratio can be obtained by reading from the second magnetic layer side during reproduction.

【００１４】ところが、このような記録媒体の記録時に
は、図３のように記録レーザー光により加熱された部分
の周囲の第２の磁性層からの漏洩磁界が第１の磁性層の
加熱された部分に作用する。この漏洩磁界は第２の磁性
層が補償組成よりも希土類過剰の場合は第１の磁性層に
対して消去方向に作用するが、その大きさは室温での第
２の磁性層の磁化の大きさに依存し、補償組成から希土
類過剰になるに従って大きくなる。However, at the time of recording on such a recording medium, the leakage magnetic field from the second magnetic layer around the portion heated by the recording laser beam as shown in FIG. 3 is heated by the heated portion of the first magnetic layer. Act on. This leakage magnetic field acts on the first magnetic layer in the erasing direction when the second magnetic layer is more rare earth than the compensating composition, but its magnitude is the magnitude of the magnetization of the second magnetic layer at room temperature. It becomes larger as the rare earth excesses from the compensation composition.

【００１５】以上のように記録開始磁界Ｈｏ、飽和磁界
Ｈｓは第２の磁性層の組成によって変化する。ここで、
ＨｏおよびＨｓの絶対値を共に小さくし、外部磁界に対
する感度の良好な記録媒体を得るためには、第２の磁性
層の組成を調整し、その補償温度が８０℃以上、１５０
℃以下の範囲になるように設定することが好ましい。As described above, the recording start magnetic field Ho and the saturation magnetic field Hs change depending on the composition of the second magnetic layer. here,
In order to reduce both the absolute values of Ho and Hs and obtain a recording medium with good sensitivity to an external magnetic field, the composition of the second magnetic layer is adjusted so that the compensation temperature is 80 ° C. or higher, 150 ° C. or higher.
It is preferable to set the temperature to be in the range of ℃ or less.

【００１６】この範囲を外れ、第２の磁性層の補償温度
が８０℃未満となると、第１の磁性層に対し第２の磁性
層から記録磁区を収縮させる方向に働いていた漏洩磁界
が小さくなるため、Ｈｏが図１における負の方向に大き
くなるばかりか、高磁界により記録を行った場合に記録
磁区が拡大し、高密度記録時に記録マーク間の干渉によ
るＣＮ比の低下が現れる。If the temperature is out of this range and the compensation temperature of the second magnetic layer is less than 80 ° C., the leakage magnetic field acting on the first magnetic layer in the direction of contracting the recording magnetic domain from the second magnetic layer is small. Therefore, Ho increases not only in the negative direction in FIG. 1, but also when recording is performed by a high magnetic field, the recording magnetic domain expands, and the CN ratio decreases due to interference between recording marks during high density recording.

【００１７】一方、第２の磁性層の補償温度が１５０℃
を超えると、第１の磁性層のキュリー温度以上となって
も第２の磁性層が垂直異方性を示し、まず第２の磁性層
に記録磁区が形成され、これが第１の磁性層に転写され
るというメカニズムで記録が行われるため、本発明によ
るＣＮ比向上の効果が見られない。On the other hand, the compensation temperature of the second magnetic layer is 150 ° C.
Beyond the above, the second magnetic layer exhibits perpendicular anisotropy even if the Curie temperature of the first magnetic layer is reached or higher, and a recording magnetic domain is first formed in the second magnetic layer. Since recording is performed by the mechanism of transfer, the effect of improving the CN ratio according to the present invention cannot be seen.

【００１８】本発明の光磁気記録媒体は前記のように第
１の磁性層から第２の磁性層に交換相互作用により記録
状態が転写されることにより記録が行われる。従って、
まず、第１の磁性層に安定な記録磁区が形成されること
が必要である。ここで第１の磁性層の膜厚が薄いと第１
の磁性層の垂直異方性および保磁力が小さくなり、微小
な記録磁区は不安定となるため、この記録磁区が第２の
磁性層に転写されても高いＣＮ比は得られない。In the magneto-optical recording medium of the present invention, recording is performed by transferring the recording state from the first magnetic layer to the second magnetic layer by the exchange interaction as described above. Therefore,
First, it is necessary to form stable recording magnetic domains in the first magnetic layer. If the thickness of the first magnetic layer is thin, the first
Since the perpendicular anisotropy and the coercive force of the magnetic layer become small and the minute recording magnetic domain becomes unstable, a high CN ratio cannot be obtained even if this recording magnetic domain is transferred to the second magnetic layer.

【００１９】一方、第１の磁性層の膜厚が大きいと磁性
層面内の熱伝導が大きくなり、記録時の記録マーク間の
熱干渉が大きくなるため、やはり高密度記録時に高いＣ
Ｎ比は得られない。以上の理由により高いＣＮ比を得る
ためには、本発明における第１の磁性層の膜厚が１５ｎ
ｍ以上、３０ｎｍ以下の範囲であることが好ましい。On the other hand, if the film thickness of the first magnetic layer is large, the heat conduction in the surface of the magnetic layer is large and the thermal interference between the recording marks during recording is large, so that the high C is also high during high density recording.
N ratio cannot be obtained. For the above reason, in order to obtain a high CN ratio, the film thickness of the first magnetic layer in the present invention is 15 n.
The range is preferably m or more and 30 nm or less.

【００２０】[0020]

【発明の実施の形態】本発明において、第１の磁性層と
しては例えば、ＴｂＦｅＣｏ、ＤｙＦｅＣｏ、ＴｂＤｙ
ＦｅＣｏ、ＤｙＧｄＦｅＣｏ等のように大きな垂直異方
性と高い保磁力を有するフェリ磁性の重希土類−遷移金
属アモルファス合金薄膜が挙げられる。具体的には、こ
の第１の磁性層はキュリー温度が１７０℃以上、２５０
℃以下であることが、レーザーパワーに対する記録感度
や繰り返し消去・記録時の熱安定性の点で好ましい。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of the first magnetic layer include TbFeCo, DyFeCo, and TbDy.
Examples thereof include ferrimagnetic heavy rare earth-transition metal amorphous alloy thin films having large vertical anisotropy and high coercive force such as FeCo and DyGdFeCo. Specifically, the Curie temperature of the first magnetic layer is 170 ° C. or higher, 250
C. or less is preferable in terms of recording sensitivity to laser power and thermal stability during repeated erasing / recording.

【００２１】一方、第２の磁性層としては第１の磁性層
のキュリー温度以上で面内磁気異方性を示すようにする
ために、垂直磁気異方性が比較的小さく、かつ垂直磁化
膜となる温度範囲が比較的狭いこと、また再生時に高い
ＣＮを得るために、キュリー温度が比較的高く、大きな
カー回転角が得られることが好ましい。これらの条件を
満足するものとしては、例えばＧｄＦｅ、ＧｄＦｅＣ
ｏ、ＧｄＣｏ、ＧｄＴｂＦｅＣｏのようなフェリ磁性の
希土類−遷移金属アモルファス合金薄膜が挙げられる。On the other hand, in order for the second magnetic layer to exhibit in-plane magnetic anisotropy at the Curie temperature of the first magnetic layer or higher, the perpendicular magnetic anisotropy is relatively small and the perpendicular magnetic film is formed. It is preferable that the Curie temperature be relatively high and a large Kerr rotation angle be obtained in order to obtain a high CN during regeneration. Those satisfying these conditions are, for example, GdFe and GdFeC.
Examples thereof include ferrimagnetic rare earth-transition metal amorphous alloy thin films such as o, GdCo, and GdTbFeCo.

【００２２】また、前記したメカニズムで記録が行われ
るためには第１の磁性層のキュリー温度に対し、第２の
磁性層のキュリー温度が十分高いことが好ましく、具体
的にはその差が５０℃以上となるように組成を選択する
ことが望ましい。また、第２の磁性層は第１の磁性層の
キュリー温度以上で面内磁気異方性を示すように組成、
膜厚を選択することが必要である。In order to perform recording by the mechanism described above, it is preferable that the Curie temperature of the second magnetic layer is sufficiently higher than the Curie temperature of the first magnetic layer. Specifically, the difference is 50. It is desirable to select the composition so that the temperature is not lower than ° C. The second magnetic layer has a composition such that it exhibits in-plane magnetic anisotropy at the Curie temperature of the first magnetic layer or higher,
It is necessary to select the film thickness.

【００２３】さらに、これらの第１および第２の磁性層
には短波長領域でのカー回転角の向上や、耐酸化性の向
上等の目的で、Ｐｒ、Ｎｄ等の軽希土類やＴｉ、Ｃｒ、
Ｔａ等の元素を添加しても良い。Further, for the purpose of improving the Kerr rotation angle in the short wavelength region and improving the oxidation resistance, these first and second magnetic layers contain light rare earths such as Pr and Nd, and Ti and Cr. ,
An element such as Ta may be added.

【００２４】本発明における記録媒体の具体的な構成の
例としては、ガラス、プラスチック等の透明な基板上に
誘電体膜、上記の二層よりなる磁性膜、誘電体膜、反射
膜の順に積層したものが挙げられる。この場合、前記の
理由で第２の磁性層は第１の磁性層よりもレーザー光が
照射される側に配置するのが好ましい。一方、上記の誘
電体膜としては磁性体膜を酸化から保護する目的の他
に、磁性体膜によるカー回転角を大きくする目的を有
し、例えばＡｌＮ、ＳｉＮ、ＳｉＡｌＮ、ＳｉＡｌＯＮ
等の窒化物やＳｉＯ、ＴａＯ等の酸化物、ＺｎＳ等の硫
化物が挙げられる。さらに、反射層は、再生時のカー回
転角を増加させる作用を有すると共に、記録レーザーパ
ワーに対する感度を調節したり、記録時の磁性体膜内の
熱伝導を制御し、高いＣＮ比を得るために有効である。
この反射層としては、例えば、Ａｌ、ＡｌＴｉ、ＡｌＴ
ａ等よりなる薄膜が用いられる。図４に本発明における
光磁気記録媒体の断面の一例を示す。As an example of the specific constitution of the recording medium in the present invention, a dielectric film, a magnetic film consisting of the above two layers, a dielectric film and a reflective film are laminated in this order on a transparent substrate such as glass or plastic. Some of them In this case, it is preferable that the second magnetic layer is arranged closer to the side irradiated with the laser light than the first magnetic layer for the above reason. On the other hand, the above-mentioned dielectric film has the purpose of increasing the Kerr rotation angle of the magnetic film in addition to the purpose of protecting the magnetic film from oxidation. For example, AlN, SiN, SiAlN, SiAlON.
And the like, oxides such as SiO and TaO, and sulfides such as ZnS. Furthermore, the reflective layer has the function of increasing the Kerr rotation angle during reproduction, adjusts the sensitivity to the recording laser power, and controls the heat conduction in the magnetic film during recording to obtain a high CN ratio. Is effective for.
Examples of the reflective layer include Al, AlTi, and AlT.
A thin film made of a or the like is used. FIG. 4 shows an example of a cross section of the magneto-optical recording medium according to the present invention.

【００２５】[0025]

【実施例】以下に本発明について実施例、比較例により
詳細に説明する。EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples.

【００２６】〔実施例１〜３、比較例１、２〕４個のタ
ーゲットを備えたスパッタ装置内に、グルーブおよびプ
リフォーマット信号が刻まれたポリカーボネート製のデ
ィスク状基板およびカー効果測定用のガラス基板を配置
した。次にこのスパッタ装置内を５×１０^-7Ｔｏｒｒ以
下にまで排気した後、ＡｒとＮ₂ の混合ガスをスパッタ
ガスとし、１×１０^-2Ｔｏｒｒのスパッタガス圧でＳｉ
ターゲットにより厚さ１００ｎｍのＳｉＮ誘電体膜を成
膜した。次に、３×１０^-3ＴｏｒｒのＡｒガス中でＧｄ
ＦｅＣｏターゲットにより、厚さ７ｎｍの第２の磁性層
を、続いてＴｂＦｅＣｏターゲットにより、厚さ１５ｎ
ｍの第１の磁性層を積層した。さらに、厚さ２５ｎｍの
ＳｉＮ誘電体層を最初の誘電体層と同じ条件で積層し、
さらに１．５×１０^-3ＴｏｒｒのＡｒ中でＡｌ₉₆Ｔｉ₄
の組成のターゲットにより厚さ７０ｎｍの反射層を成膜
することにより光磁気記録膜を作製した。[Examples 1 to 3 and Comparative Examples 1 and 2] A disk-shaped substrate made of polycarbonate with grooves and preformatted signals and glass for measuring the Kerr effect in a sputtering apparatus equipped with four targets. The substrate was placed. Next, after exhausting the inside of the sputtering apparatus to 5 × 10 ⁻⁷ Torr or less, a mixed gas of Ar and N ₂ is used as a sputtering gas and Si is sputtered at a sputtering gas pressure of 1 × 10 ⁻² Torr.
A 100 nm thick SiN dielectric film was formed on the target. Next, Gd in Ar gas of 3 × 10 ⁻³ Torr
The FeCo target was used to form a 7 nm thick second magnetic layer, followed by the TbFeCo target, a thickness of 15 nm.
m first magnetic layer was laminated. Further, a 25 nm thick SiN dielectric layer is laminated under the same conditions as the first dielectric layer,
Further, Al ₉₆ Ti _{4 in} Ar of 1.5 × 10 ⁻³ Torr
A magneto-optical recording film was produced by forming a 70 nm-thick reflective layer using a target having the above composition.

【００２７】本実施例では成膜の際に第２の磁性層の組
成をＧｄＦｅＣｏターゲット上にＧｄのチップを置き、
その数を変化させることにより第２の磁性層の組成を変
化させた。この第２の磁性層であるＧｄＦｅＣｏ層はい
ずれもキュリー温度が約３５０℃であるが、その補償温
度は、２０℃、８０℃、１１０℃、１５０℃、２００℃
であるものをそれぞれ作成した。この時、第１の磁性層
であるＴｂＦｅＣｏ層のキュリー温度は２００℃、室温
での保磁力は８（ｋＯｅ）であった。これらの光磁気記
録膜のカーヒステリシスループ測定の結果、補償温度が
１５０℃以下の第２の磁性層を用いた記録膜の場合、第
１の磁性層のキュリー温度以上で第２の磁性層が面内異
方性を示すのに対し、補償温度が２００℃の第２の磁性
層を用いた記録膜の場合、第１の磁性層のキュリー温度
以上で第２の磁性層が垂直異方性を示すことが分かっ
た。In this embodiment, the composition of the second magnetic layer was set to GdFeCo target on the GdFeCo target at the time of film formation.
The composition of the second magnetic layer was changed by changing the number. The Curie temperature of the second magnetic layer, which is the GdFeCo layer, is about 350 ° C., but the compensation temperature is 20 ° C., 80 ° C., 110 ° C., 150 ° C., 200 ° C.
I created each one. At this time, the Curie temperature of the TbFeCo layer as the first magnetic layer was 200 ° C., and the coercive force at room temperature was 8 (kOe). As a result of Kerr hysteresis loop measurement of these magneto-optical recording films, in the case of the recording film using the second magnetic layer having a compensation temperature of 150 ° C. or lower, the second magnetic layer was formed at the Curie temperature of the first magnetic layer or higher. In contrast to the in-plane anisotropy, in the case of a recording film using the second magnetic layer having a compensation temperature of 200 ° C., the second magnetic layer has a perpendicular anisotropy at the Curie temperature of the first magnetic layer or higher. Was found to show.

【００２８】これらの記録膜を有する光磁気ディスクを
８３０ｎｍの半導体レーザーを有する記録再生特性評価
装置に取り付け、基板側よりレーザー光を入射し、まず
消去を行った後、線速度６．０３ｍ／ｓｅｃ、記録周波
数３．９ＭＨｚ、記録レーザーパワー７ｍＷ、記録パル
ス幅６０ｎｓｅｃの条件でＣＮ比の記録磁界依存性の測
定を行った。この測定結果を表１に示す。この結果よ
り、補償温度が８０、１１０、および１５０℃である第
２の磁性層を有する光磁気ディスクの場合は、Ｈｏ、Ｈ
ｓ共にその絶対値が小さく、外部磁界に対する感度が良
好であると言える。またこれらの光磁気ディスクは良好
なＣＮ比が得られることが分かる。A magneto-optical disk having these recording films was attached to a recording / reproducing characteristic evaluation device having a semiconductor laser of 830 nm, laser light was made incident from the substrate side, and erasing was first performed, and then a linear velocity was 6.03 m / sec. The recording magnetic field dependence of the CN ratio was measured under the following conditions: recording frequency 3.9 MHz, recording laser power 7 mW, recording pulse width 60 nsec. The results of this measurement are shown in Table 1. From this result, in the case of the magneto-optical disk having the second magnetic layer having the compensation temperatures of 80, 110, and 150 ° C., Ho, H
It can be said that both s have small absolute values and have good sensitivity to an external magnetic field. Further, it is understood that these magneto-optical disks can obtain a good CN ratio.

【００２９】一方、図５に実施例１の補償温度が８０℃
である第２の磁性層を有するディスクと比較して示した
が、比較例１の補償温度が２０℃である第２の磁性層を
有するディスクの場合、Ｈｏの値がマイナスの側に大き
くなり、外部磁界に対する感度が低いとともに、高磁界
側でのＣＮ比の低下が見られ、高いＣＮ比が得られる磁
界の範囲が狭いことが分かる。また、第１の磁性層のキ
ュリー温度以上の温度範囲において第２の磁性層が垂直
磁化膜となる比較例２のディスクの場合、他のディスク
に比べ、ＣＮ比が低いことが分かる。On the other hand, in FIG. 5, the compensation temperature of Example 1 is 80 ° C.
However, in the case of the disc having the second magnetic layer of Comparative Example 1 having a compensation temperature of 20 ° C., the value of Ho increases to the negative side. The sensitivity to external magnetic fields is low, and the CN ratio on the high magnetic field side is low, indicating that the range of the magnetic field where a high CN ratio can be obtained is narrow. Further, it can be seen that in the case of the disk of Comparative Example 2 in which the second magnetic layer is the perpendicularly magnetized film in the temperature range equal to or higher than the Curie temperature of the first magnetic layer, the CN ratio is lower than that of the other disks.

【００３０】以上の結果より、第２の磁性層の補償温度
が８０℃以上、１５０℃以下の範囲であれば、外部磁界
に対する感度が高く、磁界の強さの広い範囲でＣＮ比の
高い光磁気記録媒体が得られることが分かる。From the above results, when the compensation temperature of the second magnetic layer is in the range of 80 ° C. or higher and 150 ° C. or lower, the sensitivity to the external magnetic field is high and the light having a high CN ratio in a wide range of the magnetic field strength is obtained. It can be seen that a magnetic recording medium can be obtained.

【００３１】〔実施例４〜６、比較例３、４〕第２の磁
性層の補償温度を１５０℃とし、基板上に前記実施例、
比較例と同様の方法でＳｉＮ誘電体層、第２の磁性層、
第１の磁性層、ＳｉＮ誘電体層、ＡｌＴｉ反射層を順次
形成した。この際第２の磁性層の膜厚を７ｎｍ、その他
の第１の磁性層以外各層の膜厚は前記実施例、比較例と
同一とし、第１の磁性層の膜厚のみを１１、１５、２
０、３０、４０ｎｍと変化させた。これらの記録膜を有
する光磁気ディスクを前記実施例と同様の方法で、ＣＮ
比の記録バイアス磁界依存性の測定を行った。これらの
測定結果を表２に示す。[Examples 4 to 6, Comparative Examples 3 and 4] The compensation temperature of the second magnetic layer was set to 150 ° C., and the above-mentioned Examples were formed on the substrate.
In the same manner as in the comparative example, the SiN dielectric layer, the second magnetic layer,
A first magnetic layer, a SiN dielectric layer, and an AlTi reflective layer were sequentially formed. At this time, the film thickness of the second magnetic layer is 7 nm, the film thickness of each layer other than the first magnetic layer is the same as that of the above-mentioned Examples and Comparative Examples, and only the film thickness of the first magnetic layer is 11, 15, Two
It was changed to 0, 30, and 40 nm. A magneto-optical disk having these recording films was treated with CN in the same manner as in the above embodiment.
The recording bias magnetic field dependence of the ratio was measured. Table 2 shows the measurement results.

【００３２】表から分かるように、これらの記録磁界感
度はほとんど変化がない。しかし、第１の磁性体層の膜
厚が１５、２０、３０ｎｍの場合は高いＣＮ比が得られ
るのに対し、１１、４０ｎｍの場合はＣＮ比が前者に比
べて低くなっていることが分かる。以上の結果より、本
実施例、比較例の条件で光磁気記録膜の成膜を行った場
合、第１の磁性層の膜厚は１５ｎｍ以上、３０ｎｍ以下
の範囲であれば磁界感度が高く、かつＣＮ比の高い光磁
気記録媒体が得られることが分かる。As can be seen from the table, these recording magnetic field sensitivities hardly change. However, it can be seen that a high CN ratio is obtained when the film thickness of the first magnetic layer is 15, 20, 30 nm, whereas the CN ratio is lower when it is 11, 40 nm as compared with the former. . From the above results, when the magneto-optical recording film is formed under the conditions of this example and the comparative example, the magnetic field sensitivity is high when the thickness of the first magnetic layer is in the range of 15 nm or more and 30 nm or less, It is also understood that a magneto-optical recording medium having a high CN ratio can be obtained.

【００３３】[0033]

【表１】 [Table 1]

【００３４】[0034]

【表２】 [Table 2]

【００３５】[0035]

【発明の効果】以上のように磁性層を磁気的に交換結合
した第１の磁性層および第２の磁性層の二層とし、第２
の磁性層が第１の磁性層のキュリー温度以上で面内磁化
膜となるようにした光磁気記録膜において、第２の磁性
層の補償温度を８０℃以上、１５０℃以下の範囲とする
一方、第１の磁性層の膜厚を１５ｎｍ以上、３０ｎｍ以
下の範囲とすることにより、記録、消去の際の磁界感度
が高く、かつ外部磁界強度の広い範囲でＣＮ比の高い光
磁気記録媒体が得られ、記録磁界の小さな磁界変調方式
でも、比較的記録磁界の大きな光変調方式でも良好な記
録特性での高密度記録が可能となる。As described above, the magnetic layer is composed of the two layers of the magnetically exchange-coupled first magnetic layer and second magnetic layer, and the second magnetic layer is formed.
In the magneto-optical recording film in which the magnetic layer is an in-plane magnetized film at the Curie temperature of the first magnetic layer or higher, the compensation temperature of the second magnetic layer is set in the range of 80 ° C to 150 ° C. By setting the film thickness of the first magnetic layer in the range of 15 nm or more and 30 nm or less, a magneto-optical recording medium having a high magnetic field sensitivity at the time of recording and erasing and a high CN ratio in a wide range of external magnetic field strength can be provided. Thus, high-density recording with good recording characteristics can be achieved by a magnetic field modulation method with a small recording magnetic field or an optical modulation method with a relatively large recording magnetic field.

【図面の簡単な説明】[Brief description of drawings]

【図１】一般的な光磁気記録媒体の記録バイアス磁界に
よるＣＮ比の変化を示す特性図である。FIG. 1 is a characteristic diagram showing a change in CN ratio due to a recording bias magnetic field of a general magneto-optical recording medium.

【図２】本発明による光磁気記録媒体の記録メカニズム
を示す説明図である。FIG. 2 is an explanatory diagram showing a recording mechanism of a magneto-optical recording medium according to the present invention.

【図３】本発明による光磁気記録媒体における記録部分
の周囲の第２の磁性層からの漏洩磁界の様子を示す説明
図である。FIG. 3 is an explanatory diagram showing a state of a leakage magnetic field from a second magnetic layer around a recording portion in the magneto-optical recording medium according to the present invention.

【図４】本発明による光磁気記録媒体の一例を示す断面
図である。FIG. 4 is a sectional view showing an example of a magneto-optical recording medium according to the present invention.

【図５】本発明における実施例１および比較例１におけ
る光磁気記録媒体のＣＮ比の記録磁界依存性を示す特性
図である。FIG. 5 is a characteristic diagram showing the recording magnetic field dependence of the CN ratio of the magneto-optical recording media in Example 1 and Comparative Example 1 of the present invention.

【符号の説明】[Explanation of symbols]

１ 基板 ２ 誘電体層 ３ 第２の磁性層 ４ 第１の磁性層 ５ 誘電体層 ６ 反射層 1 Substrate 2 Dielectric Layer 3 Second Magnetic Layer 4 First Magnetic Layer 5 Dielectric Layer 6 Reflective Layer

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 基板上にフェリ磁性の希土類−遷移金属
アモルファス合金を主とする第１の磁性層および第２の
磁性層を有し、第２の磁性層のキュリー温度が第１の磁
性層のキュリー温度より高く、第１の磁性層のキュリー
温度未満の温度範囲において、この第１の磁性層と第２
の磁性層がいずれも垂直磁気異方性を示し、磁気的に交
換結合をしているのに対し、第１の磁性層のキュリー温
度以上、第２の磁性層のキュリー温度未満の温度範囲に
おいては、第２の磁性層が面内磁気異方性を示す光磁気
記録媒体において、第２の磁性層の補償温度が８０℃以
上、１５０℃以下の範囲にあることを特徴とする光磁気
記録媒体。1. A first magnetic layer having a ferrimagnetic rare earth-transition metal amorphous alloy as a main component and a second magnetic layer on a substrate, wherein the Curie temperature of the second magnetic layer is the first magnetic layer. In a temperature range higher than the Curie temperature of the first magnetic layer and lower than the Curie temperature of the first magnetic layer.
In the temperature range above the Curie temperature of the first magnetic layer but below the Curie temperature of the second magnetic layer, while all of the magnetic layers exhibit perpendicular magnetic anisotropy and are magnetically exchange-coupled. Is a magneto-optical recording medium in which the second magnetic layer exhibits in-plane magnetic anisotropy, wherein the compensation temperature of the second magnetic layer is in the range of 80 ° C. or higher and 150 ° C. or lower. Medium. 【請求項２】 第１の磁性層の膜厚が１５ｎｍ以上、３
０ｎｍ以下である請求項１に記載の光磁気記録媒体。2. The film thickness of the first magnetic layer is 15 nm or more, 3
The magneto-optical recording medium according to claim 1, which has a thickness of 0 nm or less.