JPH0536134A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To make reproducing signal of a magneto-optical disk made from MnBi compound as a recording material large and to enhance repeating stability of recording and reproducing characteristics. CONSTITUTION:The recording material is MnBi-X (where X expresses at least one kind of B and C). B and C, which is small in ion diameter, enter into a position between lattice of MnBi to suppress structural phase change of MnBi from low temp. phase to high temp. phase. In this result, thermomagnetic recording is executed without remaining high temp. phase of metastable state in the room temp.

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は光磁気記録媒体に関し、
さらに詳しくは書き換え可能な光磁気ディスク等に用い
られ、磁気カー効果あるいは磁気ファラデー効果等の磁
気光学効果を用いて読み出すことのできる光磁気記録媒
体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium,
More specifically, the present invention relates to a magneto-optical recording medium which is used in a rewritable magneto-optical disk or the like and which can be read using a magneto-optical effect such as a magnetic Kerr effect or a magnetic Faraday effect.

【０００２】[0002]

【従来の技術】光磁気記録媒体の材料としては、主とし
て以下の条件が要求される。 （ａ）垂直磁化膜であること。 （ｂ）大きな保磁力を有していること。 （ｃ）カー回転角が大きいこと。 Ｆｅ，Ｃｏ等にＴｂ，Ｇｄ等の重希土類を添加した場
合、磁気異方性が増加し垂直磁化膜になることが知られ
ている。こうしたことから、光磁気記録媒体の材料とし
てＧｄＴｂＦｅ，ＤｙＦｅ，ＧｄＣｏ，ＴｂＣｏ，Ｔｂ
ＤｙＦｅ，ＴｂＦｅＣｏ等の重希土類−３ｄ遷移金属非
晶質合金薄膜が前記の条件を満足し、かつ量産に適し、
読み出しノイズのないことから有望とされている。特に
ＴｂＦｅＣｏは、有望視され、実用材料となっている。2. Description of the Related Art The following conditions are mainly required as materials for magneto-optical recording media. (A) A perpendicular magnetization film. (B) It has a large coercive force. (C) The car rotation angle is large. It is known that when a heavy rare earth element such as Tb or Gd is added to Fe or Co or the like, the magnetic anisotropy increases and a perpendicular magnetization film is formed. For these reasons, GdTbFe, DyFe, GdCo, TbCo, Tb are used as materials for the magneto-optical recording medium.
A heavy rare earth-3d transition metal amorphous alloy thin film such as DyFe or TbFeCo satisfies the above conditions and is suitable for mass production,
Promising because there is no read noise. TbFeCo is particularly promising and has become a practical material.

【０００３】一方、光磁気記録の高密度化の手段として
短波長レーザを使用し、記録領域を小さくすることが検
討されている。しかし、重希土類−３ｄ遷移金属非晶質
合金薄膜は、波長が短くなるにしたがってカー回転角が
小さくなるため、短波長レーザにより再生した場合、再
生出力が低下する。このため、新たな短波長用光磁気記
録材料が必要になる。ＭｎＢｉ化合物は、基板上にＢｉ
とＭｎを順次成膜したＭｎ−Ｂｉ積層膜を加熱し反応さ
せると、ＢｉのＣ軸配向性が保存されて、Ｃ軸配向のＭ
ｎＢｉ化合物となる。ＭｎＢｉ化合物は、Ｃ軸に強い磁
気異方性を有するために垂直磁化膜となる。また、Ｍｎ
Ｂｉ化合物は、短波長域においてもカー回転角が大きい
ため短波長用光磁気記録材料として有望である。基板上
にＢｉとＭｎを順次成膜したＭｎ−Ｂｉ積層膜を加熱し
反応させるためには、３００℃以上の温度雰囲気中に積
層膜を保持する必要があり、一般的には酸化防止のため
に真空電気炉内で反応を行っている。On the other hand, using a short-wavelength laser as a means for increasing the density of magneto-optical recording to reduce the recording area has been studied. However, since the Kerr rotation angle of the heavy rare earth-3d transition metal amorphous alloy thin film becomes smaller as the wavelength becomes shorter, the reproduction output decreases when reproduced by a short wavelength laser. Therefore, a new magneto-optical recording material for short wavelength is needed. The MnBi compound is Bi on the substrate.
When the Mn-Bi laminated film in which Mn and Mn are sequentially formed is heated and reacted, the C-axis orientation of Bi is preserved and the M-axis of M of C-axis orientation is preserved.
It becomes an nBi compound. Since the MnBi compound has a strong magnetic anisotropy in the C axis, it becomes a perpendicular magnetization film. Also, Mn
Since the Bi compound has a large Kerr rotation angle even in the short wavelength region, it is promising as a magneto-optical recording material for short wavelength. In order to heat and react the Mn-Bi laminated film in which Bi and Mn are sequentially formed on the substrate, it is necessary to hold the laminated film in an atmosphere at a temperature of 300 ° C. or higher. The reaction is carried out in a vacuum electric furnace.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、ＭｎＢ
ｉ化合物を光磁気記録材料として用いるためには次のよ
うな問題点がある。光磁気記録媒体の記録の原理は、レ
ーザ照射により記録材料の温度が磁気転移点を越えた部
分の磁化が、冷却過程で外部磁界の方向に向くことによ
る。ＭｎＢｉ化合物の磁気転移点は、１次の構造相転移
点と一致しているため、記録時の冷却過程で結晶構造の
異なる高温相が準安定状態として室温に残ることにな
る。この高温相のカー回転角はＮｉＡｓ型の低温相より
も小さいため、再生出力は低下してしまう。また、記録
・消去・再生を繰り返す過程で準安定状態の高温相が、
低温相に変態するため、記録情報が保存されなくなる。
本発明の目的は、このような従来の問題点を解決して、
再生信号が大きく、記録再生特性の繰り返し安定性の良
好なＭｎＢｉ系化合物を記録材料とする光磁気記録媒体
を提供することを目的とする。[Problems to be Solved by the Invention] However, MnB
There are the following problems in using the i compound as a magneto-optical recording material. The principle of recording on a magneto-optical recording medium is that the magnetization of the portion where the temperature of the recording material exceeds the magnetic transition point due to laser irradiation is directed toward the external magnetic field during the cooling process. Since the magnetic transition point of the MnBi compound coincides with the primary structural phase transition point, a high temperature phase having a different crystal structure remains at room temperature as a metastable state during the cooling process during recording. Since the Kerr rotation angle of this high temperature phase is smaller than that of the NiAs type low temperature phase, the reproduction output is reduced. Also, in the process of repeating recording, erasing and reproducing, the high temperature phase in the metastable state
Since it transforms to a low temperature phase, recorded information cannot be stored.
The object of the present invention is to solve such conventional problems,
It is an object of the present invention to provide a magneto-optical recording medium which uses a MnBi-based compound as a recording material, which has a large reproduction signal and is excellent in repeated stability of recording / reproduction characteristics.

【０００５】[0005]

【課題を解決するための手段】本発明は、膜面に垂直な
磁気容易軸を有するＭｎＢｉ−Ｘ（但し、ＸはボロンＢ
と炭素Ｃのうちの少なくとも１種類を示す。）で表され
る組成の化合物を情報記録材料とすることを特徴とする
光磁気記録媒体である。According to the present invention, MnBi-X having a magnetic easy axis perpendicular to the film surface (where X is boron B) is used.
And at least one of carbon C is shown. The present invention is a magneto-optical recording medium characterized by using a compound having a composition represented by (4) as an information recording material.

【０００６】[0006]

【作用】ＮｉＡｓ型ＭｎＢｉ化合物の構造相転移は、Ｍ
ｎが６配位の格子位置から、５配位の格子間位置に移動
することにより発生する。そのため、格子間位置を他の
原子であらかじめ埋めてしまうことにより低温相を安定
化させることができる。ＢとＣは、イオン半径が小さい
ため格子間位置に選択的にはいることができ、構造相転
移を抑えることができる。The structural phase transition of NiAs-type MnBi compound is M
It occurs when n moves from a hexacoordinate lattice position to a pentacoordinate lattice position. Therefore, the low temperature phase can be stabilized by previously filling the interstitial positions with other atoms. Since B and C have small ionic radii, they can selectively enter interstitial positions and suppress structural phase transition.

【０００７】[0007]

【実施例】次に本発明の実施例について、図面を参照し
て詳細に説明する。図１は、本発明の実施例における光
磁気記録媒体の部分断面図を示すものである。この光磁
気記録媒体は、ガラス基板１上に、中間層（スパッタに
よる窒化珪素膜）２を９５ｎｍの厚さに、ＭｎＢｉ−Ｂ
層（１０at％ Ｂ）３を蒸着で２０ｎｍの厚さに、干渉
層（スパッタによる窒化珪素膜）４を２０ｎｍの厚さ
に、反射層（スパッタによるＡｌ膜）５を３０ｎｍの厚
さに順次成膜し、ＮｉＡｓ型化合物を形成するように熱
処理した。この記録媒体を構造相転移温度以上に加熱し
た後、室温に急冷したところ、カー回転角の変化は見ら
れなかった。ＭｎＢｉ−Ｂ層の成膜には、蒸着法のほ
か、スパッタ法、イオンプレーティング法、イオンクラ
スタービーム法等が可能である。また、ＭｎＢｉ−Ｃ記
録層においても同様の効果がみられた。Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a partial sectional view of a magneto-optical recording medium according to an embodiment of the present invention. In this magneto-optical recording medium, an intermediate layer (silicon nitride film formed by sputtering) 2 having a thickness of 95 nm is formed on a glass substrate 1 by using MnBi-B.
The layer (10 at% B) 3 is vapor-deposited to a thickness of 20 nm, the interference layer (sputtered silicon nitride film) 4 to a thickness of 20 nm, and the reflective layer (sputtered Al film) 5 to a thickness of 30 nm. It was filmed and heat treated to form a NiAs-type compound. When this recording medium was heated above the structural phase transition temperature and then rapidly cooled to room temperature, no change in Kerr rotation angle was observed. The MnBi-B layer can be formed by a vapor deposition method, a sputtering method, an ion plating method, an ion cluster beam method, or the like. The same effect was also observed in the MnBi-C recording layer.

【０００８】[0008]

【発明の効果】以上説明したように、本発明による光磁
気記録媒体は、磁気転移点以上の温度から急冷した場合
もカー回転角に変化はなく、本発明は高性能な光磁気記
録媒体を提供するという効果を有する。As described above, the Kerr rotation angle of the magneto-optical recording medium according to the present invention does not change even when it is rapidly cooled from the temperature above the magnetic transition point, and the present invention provides a high-performance magneto-optical recording medium. It has the effect of providing.

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

【図１】本発明の一実施例の断面図である。FIG. 1 is a sectional view of an embodiment of the present invention.

【符号の説明】[Explanation of symbols]

１ ガラス基板 ２ 中間層 ３ ＭｎＢｉ−Ｂ層 ４ 干渉層 ５ 反射層 1 Glass Substrate 2 Intermediate Layer 3 MnBi-B Layer 4 Interference Layer 5 Reflective Layer

Claims (1)

【特許請求の範囲】 【請求項１】 膜面に垂直な磁気容易軸を有するＭｎＢ
ｉ−Ｘ（但し、ＸはボロンＢと炭素Ｃのうちの少なくと
も１種類を示す。）で表される組成の化合物を情報記録
材料とすることを特徴とする光磁気記録媒体。Claims: 1. MnB having a magnetic easy axis perpendicular to the film surface.
A magneto-optical recording medium comprising a compound having a composition represented by i-X (where X represents at least one of boron B and carbon C) as an information recording material.