JPH01300445A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To increase the Kerr rotational angle of the recording medium and to improve the chemical stability thereof by using the material expressed by RxMyTzAn to form a magnetized film and to forming the film in a manner as to satisfy specific conditions. CONSTITUTION:The magnetized film of the magneto-optical recording medium consisting of the amorphous magnetized film having the axis of easy magnetization in the direction perpendicular to the film plane is formed of the material expressed by the formula RxMyTzAn. In the formula, R is at least one kind selected from heavy rare earth elements; M is at least one kind selected from Ti, Zr and Hf; T is Fe or the combination of Fe and Co; A is at least one kind selected from the group consisting of Al, B, Bi, and Sb; (x), (y), (z) and (n) are respectively in 4<=x<=15, 4<y<=15, 70<=z<=92, and 0<=n<=10 ranges in molar %. The Kerr rotational effect is improved in this way and, therefore, the S/N is increased and the recording medium having the excellent corrosion resistance and the chemical stability is obtd.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、光磁気メモリー、磁気記録表示素子等に使用
される光磁気記録媒体に関し、特に膜面と垂直な方向に
磁化容易磁気を有し、保磁力、カー回転角が大きく、Ｓ
／Ｎ比が良好でかつ化学的に安定で、光磁気記録特性の
優れた記録媒体に関する（従来の技術とその問題点） 従来、光磁気記録媒体としては、Ｍ　ｎ　Ｂ　ｉ等の多
結晶膜、ＧＩＧ等の単結晶膜、及びＧｄＴｂＦｅＣｏ等
の希土類、遷移金属類を主成分とする非晶質合金薄膜等
がよく知られているが、多結晶薄膜は、カー回転角が大
きい特徴を有する反面、結晶粒界が存在するために光の
散乱が発生し、Ｓ／Ｎ比が極端に小さくなる欠点がある
。又、ガーネット単結晶薄膜はその磁気特性は優れてい
るが、大面積のディスクの作製が困難であるという不利
があった。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magneto-optical recording medium used for magneto-optical memories, magnetic recording display elements, etc. However, the coercive force and Kerr rotation angle are large, and S
Related to a recording medium with good /N ratio, chemical stability, and excellent magneto-optical recording characteristics (prior art and its problems) Conventionally, as a magneto-optical recording medium, a polycrystalline film such as M n B i has been used. , single crystal films such as GIG, and amorphous alloy thin films mainly composed of rare earths and transition metals such as GdTbFeCo, etc., but polycrystalline thin films have the characteristic of a large Kerr rotation angle. However, due to the presence of crystal grain boundaries, light scattering occurs, resulting in an extremely low S/N ratio. Further, although the garnet single crystal thin film has excellent magnetic properties, it has the disadvantage that it is difficult to manufacture a large-area disk.

これに対し、近年、媒体雑音が小さ（、膜の作製が比較
的容易で、工業的に有利なＧｄＴｂ　−ＦｅＣ。On the other hand, in recent years, GdTb-FeC has been developed which is industrially advantageous due to its low media noise (and relatively easy film production).

系の非晶質合金薄膜が光磁気記録媒体用磁化膜として注
目され、それを用いる記録媒体の研究が広く行なわれて
いる。例えば特開昭６０−１９３１２５、特開昭６１−
８７３０４にその例がある。しかし前者の場合には保磁
力があまり太き（ないうえに垂直磁化膜に形成すること
が煩雑であった。又後者においては耐食性が比較的に改
善されているが、希土類元素が多い組成であるため膜の
経時劣化が起こりやすいという問題があった。Amorphous alloy thin films of this type have attracted attention as magnetized films for magneto-optical recording media, and research on recording media using them has been widely conducted. For example, JP-A-60-193125, JP-A-61-
There is an example in 87304. However, in the former case, the coercive force was not very large (not only that, but it was complicated to form the perpendicularly magnetized film).Also, in the latter case, the corrosion resistance was relatively improved, but the composition was high in rare earth elements. Therefore, there was a problem in that the membrane was susceptible to deterioration over time.

このように従来公知の媒体は、最近の高密度の情報記録
には不十分てあったので、キューリー点が低く、保磁力
、カー回転角が大きく、かつ化学的に安定な薄膜が強（
要望されていた。In this way, conventionally known media have been inadequate for recent high-density information recording, so thin films with a low Curie point, large coercive force, large Kerr rotation angle, and chemical stability have been developed (
It was requested.

（問題点を解決するための手段） 本発明者らは、上記目的を達成する光磁気記録体を開発
すべ（、特にその磁化膜について多くの試作研究を重ね
た結果、前記諸欠点が効果的に克服され、光磁気記録特
性が高度に改善された実用的に望ましい磁化膜を見出し
た。(Means for Solving the Problems) The present inventors have developed a magneto-optical recording medium that achieves the above objectives (and as a result of repeated research on many prototypes, especially regarding its magnetized film, we have found that the above-mentioned drawbacks can be effectively overcome). We have overcome these problems and discovered a practically desirable magnetized film with highly improved magneto-optical recording properties.

すなわち、本発明は、膜面と垂直な方向に磁化容易軸を
有する非晶質磁化膜より成る光磁気記録媒体において、
該磁化膜が式、ＲｘＭ、Ｔ□Ａ、　（式中、Ｒは重希土
類元素から選択される少なくとも一種であり、ＭはＴｉ
、Ｚｒ及びＨｆから選択される少なくとも一種であり、
ＴはＦｅ又はＦｅとＣｏとの組み合わせであり、ＡはＡ
Ｉ、Ｂ、ＢｉおよびＳｂより成る群から選択される少な
くとも一種であり、ｘ、　ｙ、　ｚ及びｎは、それぞれ
モル％で、４≦Ｘ≦１５．４．＜Ｙ≦１５、７０≦ｚ≦
９２及び０≦ｎ≦１０の範囲である）で表わされる光磁
気記録媒体を提供するものである。That is, the present invention provides a magneto-optical recording medium comprising an amorphous magnetized film having an axis of easy magnetization in a direction perpendicular to the film surface.
The magnetized film has the formula: RxM, T□A, (wherein R is at least one selected from heavy rare earth elements, M is Ti
, at least one selected from Zr and Hf,
T is Fe or a combination of Fe and Co, and A is A
It is at least one member selected from the group consisting of I, B, Bi and Sb, and x, y, z and n are each mol%, and 4≦X≦15.4. <Y≦15, 70≦z≦
92 and 0≦n≦10).

本発明におけるＲとしては、原子番号が６３〜７】のラ
ンタノイドであり、具体的にはＥｕ、　Ｇｄ、　Ｄｙ。R in the present invention is a lanthanoid having an atomic number of 63 to 7, specifically Eu, Gd, Dy.

Ｈｏ、　Ｅｒ、　Ｔｍ、　Ｙｂ、　Ｌｕ等の元素である
。これらのうち１種もしくは２種以上を使用することが
できる。軽希土類元素のみをＲとして用いないのは飽和
磁化が高くなり過ぎ、膜の垂直磁化傾向が弱くなるため
である。尚、軽希土元素を重希土元素と併用することは
差し支えなく、この場合の軽希土元素添加量は重希土元
素に対し５０％以下とされる。These are elements such as Ho, Er, Tm, Yb, and Lu. One or more of these can be used. The reason why only a light rare earth element is not used as R is because the saturation magnetization becomes too high and the perpendicular magnetization tendency of the film becomes weak. Note that there is no problem in using the light rare earth element in combination with the heavy rare earth element, and in this case, the amount of the light rare earth element added is 50% or less with respect to the heavy rare earth element.

Ｔｉ及びＭが上記範囲にあるとき、高い耐食性と大きな
カー回転角を示す。上記範囲より少ないとき、耐食性が
低下し、それより多いときカー回転角が急激に低下する
。ＦｅをＣｏで置き換えるとキューリー温度Ｔｃとカー
回転角θ、とが大きくなるが、置換量が多過ぎると磁化
方向を反転する際に膜の温度が上昇し過ぎて安定性、書
き込み速度の点て問題が生じるので、ＦｅのＣＯによる
置換は３０重量％以下が望ましい。When Ti and M are in the above ranges, high corrosion resistance and a large Kerr rotation angle are exhibited. When the amount is less than the above range, the corrosion resistance decreases, and when it is more than the above range, the Kerr rotation angle sharply decreases. Replacing Fe with Co increases the Curie temperature Tc and the Kerr rotation angle θ, but if the amount of substitution is too large, the temperature of the film increases too much when the magnetization direction is reversed, resulting in poor stability and writing speed. Since this may cause problems, it is desirable that Fe be replaced by CO in an amount of 30% by weight or less.

このような組成の薄膜によって、カー回転角が約０５度
と極めて大きく、大気中に１力月以上放置しても磁気特
性が劣化せず、さらに保磁力および飽和磁化が大きいた
め、垂直方向に磁化容易軸を設けて、情報記録密度を格
段に高く保つことができる光磁気記録媒体を提供するこ
とができた。A thin film with such a composition has an extremely large Kerr rotation angle of about 0.5 degrees, and its magnetic properties do not deteriorate even if it is left in the atmosphere for more than a month.Furthermore, its coercive force and saturation magnetization are large, so it can be used vertically. By providing an axis of easy magnetization, it was possible to provide a magneto-optical recording medium that can maintain an extremely high information recording density.

（実施例１） 本発明の媒体をＲＦスパッタリング法により作製した場
合の組成と磁気特性の関係を第１表に示す。(Example 1) Table 1 shows the relationship between composition and magnetic properties when the medium of the present invention was manufactured by RF sputtering.

尚、本例においては、ＲはＧｄ、　Ｔｂ、及びＤｙのう
ち少なくとも１元素を含み、Ｎｏ、３及びＮｏ、４の試
片はＰｒを含んでいる。他の成分は第１表に示したとお
りである。又添加物としてのＡ（すなわち、Ａｌ，Ｂ、
　ＢｉおよびＳｂ）は含有されていない。In this example, R contains at least one element among Gd, Tb, and Dy, and specimens No. 3 and No. 4 contain Pr. Other ingredients are as shown in Table 1. Also, A as an additive (i.e., Al, B,
Bi and Sb) are not contained.

膜厚は、磁化を安定にし、垂直方向に磁化容易軸を実現
するため１５００人乃至３０００人とした。The film thickness was set to 1,500 to 3,000 to stabilize magnetization and realize an axis of easy magnetization in the perpendicular direction.

尚、スパッター膜の蒸着条件は、真空炉内を１×１Ｏ−
７Ｔｏｒｒまで吸気後、Ａｒガスを注入し１．５　Ｘ　
１０−２乃至３．ＯＸ　１Ｏ−２Ｔｏｒｒとし、蒸着速
度を１５０人／ｍｉｎに制御してガラス基板上に成膜し
た。磁気特性として保磁力（Ｈｃ）およびカー回転角（
θＫ）が測定され、前者には振動試料型磁力計が用いら
れ、第１表 ト 「 後者の測定はＨｅ−Ｎｅレーサーが用いられガラス基板
側より測定した。The deposition conditions for the sputtered film are 1 x 1 O-
After inhaling to 7 Torr, inject Ar gas to 1.5
10-2 to 3. A film was formed on a glass substrate at OX 1O-2 Torr and a vapor deposition rate of 150 persons/min. Coercive force (Hc) and Kerr rotation angle (
A vibrating sample magnetometer was used for the former measurement, and a He-Ne laser was used for the latter measurement from the glass substrate side.

第１表から明らかなように、本発明の媒体は保磁力Ｈｃ
が０　、７０〜０．７６　ｋ　Ｏｅ　、カー回転角θ、
は０．４６〜０．５１度と極めて太き（、優れた磁気特
性を有することが確認された。As is clear from Table 1, the medium of the present invention has a coercive force Hc
is 0, 70 to 0.76 k Oe, Kerr rotation angle θ,
is extremely thick at 0.46 to 0.51 degrees (it was confirmed that it has excellent magnetic properties).

（実施例２） 第２表は他のグループの試片に関する実験結果を示すも
のであり、各々の試片の組成は第２表に示されるとおり
である。本実験の目的は添加物Ｂ、　Ｂｉ。(Example 2) Table 2 shows the experimental results for other groups of specimens, and the composition of each specimen is as shown in Table 2. The purpose of this experiment was to use additive B, Bi.

及びＳｂの効果を調べようとしたものである。第１表と
第２表とを比較するなら、添加物がカー回転角θ、の増
大に少なからず寄与していることが類推される。The purpose of this study was to investigate the effects of Sb and Sb. Comparing Tables 1 and 2, it can be inferred that the additives contribute to a considerable extent to the increase in the Kerr rotation angle θ.

以上述べたように、本発明の光磁気記録媒体は、従来の
ものに比べて、 １）熱安定性が良好である、 ｉｉ）カー回転角が大きく、したがってＳ／Ｎが大きい
、 １１１）耐食性に優れ化学的に非常に安定である、ｉｖ
）記録密度を高（することができる、のような優れた特
性を有し、したがって本発明は、高密度の情報書き込み
及び読み出しに当たり十分な能力を発揮し、産業上極め
て有用なものである。As described above, compared to conventional media, the magneto-optical recording medium of the present invention has the following features: 1) good thermal stability; ii) a large Kerr rotation angle, and therefore a large S/N ratio; 111) corrosion resistance. excellent chemical stability, iv
Accordingly, the present invention exhibits sufficient ability for high-density information writing and reading, and is extremely useful industrially.

第２表Table 2

Claims (1)

【特許請求の範囲】[Claims] （１）膜面と垂直な方向に磁化容易軸を有する非晶質磁
化膜より成る光磁気記録媒体において、該磁化膜が式、
Ｒ＿ｘＭ＿ｙＴ＿ｚＡ＿ｎ（式中、Ｒは重希土類元素か
ら選択される少なくとも一種であり、ＭはＴｉ，Ｚｒ及
びＨｆから選択される少なくとも一種であり、ＴはＦｅ
又はＦｅとＣｏとの組み合わせであり、ＡはＡｌ，Ｂ，
ＢｉおよびＳｂより成る群から選択される少なくとも一
種であり、ｘ，ｙ，ｚ及びｎは、それぞれモル％で：４
≦ｘ≦１５，４＜ｙ≦１５，７０≦ｚ≦９２及び０≦ｎ
≦１０の範囲である）で表わされる光磁気記録媒体。(1) In a magneto-optical recording medium consisting of an amorphous magnetized film having an axis of easy magnetization perpendicular to the film surface, the magnetized film has the following formula:
R_xM_yT_zA_n (wherein R is at least one selected from heavy rare earth elements, M is at least one selected from Ti, Zr, and Hf, and T is Fe
Or a combination of Fe and Co, where A is Al, B,
At least one member selected from the group consisting of Bi and Sb, and x, y, z and n are each mol%: 4
≦x≦15, 4<y≦15, 70≦z≦92 and 0≦n
≦10).