JPH0714230A - Magneto-optical recording medium and its reproduction method - Google Patents
Magneto-optical recording medium and its reproduction methodInfo
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- JPH0714230A JPH0714230A JP15470293A JP15470293A JPH0714230A JP H0714230 A JPH0714230 A JP H0714230A JP 15470293 A JP15470293 A JP 15470293A JP 15470293 A JP15470293 A JP 15470293A JP H0714230 A JPH0714230 A JP H0714230A
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- temperature
- reproducing
- magneto
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はレーザー光などの光を用
いて情報の記録再生を行う光磁気記録媒体及びその再生
方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording / reproducing information using light such as laser light and a reproducing method thereof.
【０００２】[0002]
【従来の技術】情報処理システムにおける情報処理量の
急速な増加にともない記録容量の大きい記録媒体、とり
わけ光磁気記録媒体が注目されている。2. Description of the Related Art With the rapid increase in the amount of information processing in an information processing system, a recording medium having a large recording capacity, especially a magneto-optical recording medium, has been attracting attention.
【０００３】光磁気記録媒体への記録は、レーザー光照
射により記録膜の温度を局部的にキュリー温度以上に加
熱し、照射部の記録膜を外部磁界の向きに磁化させ、記
録磁区を形成することによって行う（熱磁気記録）。そ
の記録信号の再生は、記録消去時のレーザーパワーより
低いパワーのレーザー光を照射し、記録膜の記録状態
（記録磁区の磁化の向き）に応じて反射光あるいは透過
光の偏光面が回転する（磁気光学効果）状況を検出する
ことによって行う。In recording on a magneto-optical recording medium, the temperature of the recording film is locally heated to a Curie temperature or higher by laser light irradiation, and the recording film in the irradiated portion is magnetized in the direction of the external magnetic field to form a recording magnetic domain. (Thermomagnetic recording). The reproduction of the recording signal is performed by irradiating a laser beam having a power lower than the laser power at the time of recording and erasing, and the polarization plane of the reflected light or the transmitted light rotates depending on the recording state of the recording film (direction of magnetization of recording magnetic domain). (Magneto-optical effect) It is performed by detecting the situation.
【０００４】記録磁区が再生光のスポット径以下に小さ
くなると、再生しようとする記録磁区の前後の記録磁区
も再生光の検出範囲に含まれ、それらからの干渉により
再生信号が小さくなるためにＳ／Ｎが低下するという課
題があった。この課題の解決策として、記録したドメイ
ンがレーザー光のスポット径に比較して充分小さいと
き、レーザー光のスポットの中に２つ以上のドメインが
入るため再生時のＣ／Ｎが悪くなるので、レーザー光の
スポットの中のドメインの一つのみを再生するという方
式がある（たとえば、日経エレクトロニクス１９９１．
１０．２８（Ｎｏ．５３９）の記載文献参照）。When the recording magnetic domain becomes smaller than the spot diameter of the reproducing light, the recording magnetic domains before and after the recording magnetic domain to be reproduced are also included in the detecting range of the reproducing light, and the reproduction signal becomes small due to interference from them, so that S There is a problem that / N decreases. As a solution to this problem, when the recorded domain is sufficiently smaller than the spot diameter of the laser light, two or more domains are included in the spot of the laser light, so that the C / N at the time of reproduction is deteriorated. There is a method of reproducing only one of the domains in the laser light spot (for example, Nikkei Electronics 1991.
10.28 (No. 539)).
【０００５】以下に従来の光磁気記録媒体について説明
する。図６に示すように、光磁気記録媒体は再生層２
１、再生補助層２２、中間層２３及び記録層２４が交換
結合された４層で構成されている。A conventional magneto-optical recording medium will be described below. As shown in FIG. 6, the magneto-optical recording medium has a reproducing layer 2
1, a reproduction auxiliary layer 22, an intermediate layer 23, and a recording layer 24 are composed of four exchange-coupled layers.
【０００６】再生層２１と再生補助層２２の交換結合力
をＨ1-2、中間層２３を介して働く再生補助層２２と記
録層２４の交換結合力をＨ2-4とする。中間層２３は面
内磁化膜であるためにＨ2-4は再生補助層２２と記録層
２４を直接に積層したときの交換結合力より小さくな
る。The exchange coupling force between the reproduction layer 21 and the reproduction auxiliary layer 22 is H1-2, and the exchange coupling force between the reproduction auxiliary layer 22 and the recording layer 24 acting through the intermediate layer 23 is H2-4. Since the intermediate layer 23 is an in-plane magnetized film, H2-4 becomes smaller than the exchange coupling force when the reproduction auxiliary layer 22 and the recording layer 24 are directly laminated.
【０００７】再生層２１は、低保磁力Ｈc1のＧｄＦｅＣ
ｏ膜製の垂直磁化膜でＨc1は５０〜百Ｏｅ程度である。
再生補助層２２は、低いキュリー温度Ｔcを有するＴｂ
ＦｅＣｏ膜製の垂直磁化膜でＴcは１３０〜１６０℃
で、保磁力Ｈc2は４ｋＯｅ以下とする。室温での交換結
合力を制御するための中間層２３は、ＧｄＦｅＣｏ膜製
で、記録層２４は、高保磁力Ｈc4のＴｂＦｅＣｏ膜製の
垂直磁化膜でＨc4は１０ｋＯｅ以上とする。The reproducing layer 21 is made of GdFeC having a low coercive force Hc1.
The perpendicular magnetization film made of o film has Hc1 of about 50 to 100 Oe.
The auxiliary reproduction layer 22 is made of Tb having a low Curie temperature Tc.
Perpendicular magnetic film made of FeCo film with Tc of 130 to 160 ° C
Then, the coercive force Hc2 is set to 4 kOe or less. The intermediate layer 23 for controlling the exchange coupling force at room temperature is made of a GdFeCo film, the recording layer 24 is a perpendicular magnetization film made of a TbFeCo film having a high coercive force Hc4, and Hc4 is 10 kOe or more.
【０００８】図中の２５は初期化磁界Ｈi、２６は再生
磁界Ｈr、２７は再生光、２８は記録磁区を示す。In the figure, 25 is an initializing magnetic field Hi, 26 is a reproducing magnetic field Hr, 27 is reproducing light, and 28 is a recording magnetic domain.
【０００９】以上のように構成された光磁気記録媒体に
ついて、以下その再生動作を説明する。The reproducing operation of the magneto-optical recording medium having the above structure will be described below.
【００１０】あらかじめ、情報は光磁気記録媒体に熱磁
気記録されていて、その記録された記録磁区を再生する
方法について述べる。Information is previously thermomagnetically recorded on a magneto-optical recording medium, and a method of reproducing the recorded recording domain will be described.
【００１１】はじめに再生層２１及び再生補助層２２の
初期化を行う。すなわち、初期化磁界Ｈi２５の向きに
再生層２１及び記録層２４の磁化を向ける。これによ
り、再生層２１の記録磁区２８が消失する。このための
条件は、再生層２１については、Ｈi＞Ｈc1＋Ｈ1-2であ
り、再生補助層２２については、Ｈi＞Ｈc2＋Ｈ2-4−Ｈ
1-2である。この条件を満たすように組成、製膜条件等
を設定する。First, the reproduction layer 21 and the reproduction auxiliary layer 22 are initialized. That is, the magnetizations of the reproducing layer 21 and the recording layer 24 are oriented in the direction of the initializing magnetic field Hi25. As a result, the recording magnetic domain 28 of the reproducing layer 21 disappears. The conditions for this are Hi> Hc1 + H1-2 for the reproduction layer 21, and Hi> Hc2 + H2-4-H for the reproduction auxiliary layer 22.
1-2. The composition and film forming conditions are set so as to satisfy this condition.
【００１２】その磁化の揃った状態を保持させるため
に、Ｈc2＞Ｈ2-4−Ｈ1-2を満足するように設定する。再
生層２１の記録磁区２８は消滅磁区２９となる。In order to maintain the state of uniform magnetization, Hc2> H2-4-H1-2 is set to be satisfied. The recording magnetic domain 28 of the reproducing layer 21 becomes an erasing magnetic domain 29.
【００１３】次に再生光２７が照射される。再生時に、
再生光２７の照射によって再生層２１及び再生補助層２
２の一部分３０ａの温度が、温度Ｔd1以上かつ温度Ｔd2
以下に上昇したときに、記録層２４の磁化を再生層２１
及び再生補助層２２に転写させる。Ｈ2-4＋Ｈr＞Ｈc2＋
Ｈ1-2を満足するように設定すると、記録層２４の磁化
が再生補助層２２に転写される。また、もともと、再生
層２１の保磁力Ｈc1は小さいのでＨ1-2＞Ｈc1と設定す
れば再生層２１の磁化は再生補助層２２の向きに揃う。Next, the reproducing light 27 is irradiated. During playback,
The reproduction layer 21 and the reproduction auxiliary layer 2 are irradiated by the reproduction light 27.
The temperature of the portion 30a of 2 is equal to or higher than the temperature Td1 and is equal to the temperature Td2.
When the temperature rises below, the magnetization of the recording layer 24 is changed to the reproducing layer 21.
And the reproduction assisting layer 22. H2-4 + Hr> Hc2 +
When it is set to satisfy H1-2, the magnetization of the recording layer 24 is transferred to the reproduction assisting layer 22. Further, since the coercive force Hc1 of the reproducing layer 21 is originally small, the magnetization of the reproducing layer 21 is aligned with the direction of the reproducing auxiliary layer 22 by setting H1-2> Hc1.
【００１４】また、再生層２１及び再生補助層２２の一
部分３０ｂがキュリー温度Ｔcより高い温度Ｔd2以上に
上昇するが、Ｔc＜Ｔd2であるため、再生補助層２２の
磁化が消滅して（再生補助層の一部分２２ｂ）Ｈ2-4が
零となる。また、このとき再生磁界ＨrをＨr＞Ｈc1にな
るように設定しているため、再生層２１の磁化は再生磁
界Ｈrの方向に揃う。The portion 30b of the reproducing layer 21 and the reproducing auxiliary layer 22 rises to a temperature Td2 higher than the Curie temperature Tc, but since Tc <Td2, the magnetization of the reproducing auxiliary layer 22 disappears (reproducing auxiliary layer 22). Part of the layer 22b) H2-4 is zero. At this time, the reproducing magnetic field Hr is set so that Hr> Hc1. Therefore, the magnetization of the reproducing layer 21 is aligned in the direction of the reproducing magnetic field Hr.
【００１５】従って、再生光２７のスポットのうちで温
度Ｔd1以上かつ温度Ｔd2以下の部分からのみ記憶情報を
再生信号として読み出すことができる。これで再生光２
７のスポットの大きさよりも小さな記録磁区２８を前後
の記録磁区２８からの波形干渉なしで再生できることに
なる。Therefore, the stored information can be read out as a reproduction signal only from a portion of the spot of the reproduction light 27 having a temperature of Td1 or more and Td2 or less. This is reproduction light 2
The recording magnetic domain 28 smaller than the spot size of 7 can be reproduced without waveform interference from the recording magnetic domains 28 before and after.
【００１６】[0016]
【発明が解決しようとする課題】しかしながら上記の従
来の構成では、光磁気記録媒体の構造が４層となり、複
雑であるため各層間の制御が難しく、組成、膜厚、製膜
条件が多少変化しただけでも交換結合力が変わり再生の
動作条件が変動して、安定した再生が不可能となり動作
ができないという問題点、また、４層も製膜しなければ
ならないので製膜に手間がかかり低コスト化がはかれな
いという問題点を有していた。However, in the above-mentioned conventional structure, the structure of the magneto-optical recording medium has four layers, which is complicated and difficult to control between the layers, and the composition, film thickness and film forming conditions are slightly changed. However, the exchange coupling force changes and the operating conditions for regeneration fluctuate, and stable regeneration becomes impossible and operation cannot be performed. Also, since four layers must be formed, it takes time and effort to form the film, which is low. It had a problem that the cost could not be reduced.
【００１７】本発明は上記従来の問題点を解決するもの
で、安定した再生動作が可能で簡易な構造の光磁気記録
媒体及びその再生方法を提供することを目的とする。The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magneto-optical recording medium having a simple structure capable of stable reproducing operation and a reproducing method thereof.
【００１８】[0018]
【課題を解決するための手段】この目的を達成するため
に本発明の光磁気記録媒体及びその再生方法は、磁気的
に結合させた記録層、中間層、再生層を有し、中間層は
室温において面内磁化膜であり、かつ、中間層の補償温
度は記録層の磁化が再生層に転写を開始する温度よりも
高く、かつ、中間層のキュリー温度は再生時の昇温によ
り磁化が喪失する程度の温度である構成、及びその光磁
気記録媒体の中間層の一部が中間層のキュリー温度に到
達し、かつ、中間層の一部の温度が中間層の補償温度と
キュリー温度との間となるような強度のレーザー光で再
生する方法としたものである。In order to achieve this object, a magneto-optical recording medium and a reproducing method thereof according to the present invention have a magnetically coupled recording layer, an intermediate layer and a reproducing layer, and the intermediate layer is It is an in-plane magnetized film at room temperature, and the compensation temperature of the intermediate layer is higher than the temperature at which the magnetization of the recording layer starts transferring to the reproducing layer, and the Curie temperature of the intermediate layer is The structure is such that the temperature is at a loss, and a part of the intermediate layer of the magneto-optical recording medium reaches the Curie temperature of the intermediate layer, and a part of the temperature of the intermediate layer is equal to the compensation temperature and the Curie temperature of the intermediate layer. This is a method of reproducing with a laser beam having an intensity so as to be in the range.
【００１９】[0019]
【作用】この構成及び方法において、中間層のキュリー
温度を低くして再生中に昇温する温度に近づけると、再
生中にキュリー温度以上になる領域が生じ、そのため磁
化がその領域で消滅して記録層と再生層の相互間の交換
結合力が作用しなくなる。In this structure and method, when the Curie temperature of the intermediate layer is lowered to approach the temperature that rises during reproduction, a region having a Curie temperature or higher is generated during reproduction, so that the magnetization disappears in that region. The exchange coupling force between the recording layer and the reproducing layer does not work.
【００２０】[0020]
【実施例】以下本発明の一実施例について、図面を参照
しながら説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.
【００２１】図１及び図２に示すように、光磁気記録媒
体は、ポリカーボネイト製の基板１上に形成されたキュ
リー温度Ｔc1、保磁力Ｈc1を有するＧｄＴｂＦｅＣｏ膜
製の再生層２と、室温では面内磁化膜でキュリー温度Ｔ
c2と補償温度Ｔcompを有するＧｄＦｅＣｏ膜製の中間層
３と、キュリー温度Ｔc3，保磁力Ｈc3を有するＴｂＦｅ
Ｃｏ膜製の記録層４と、窒化珪素製の保護層５ａ，５ｂ
とで構成され、再生層２と記録層４は中間層３を介して
交換結合されている。各層はスパッタリング法または真
空蒸着法により形成し、各層の膜厚は再生層２を４０ｎ
ｍ、中間層３を１〜１０ｎｍ、記録層４を５０ｎｍと設
定した。また、キュリー温度はＴc1を３００℃程度、Ｔ
c2を２００℃、Ｔc3を３００℃程度、保磁力は室温にお
いてＨc1を１．５〜２ｋＯｅ、Ｈc3を希土類優勢（RE-r
ich）５ｋＯｅに設定した。また、中間層３の補償温度
Ｔcompは約１５０℃である。As shown in FIGS. 1 and 2, the magneto-optical recording medium has a reproducing layer 2 made of a GdTbFeCo film having a Curie temperature Tc1 and a coercive force Hc1 formed on a substrate 1 made of polycarbonate, and a surface at room temperature. Curie temperature T in the inner magnetized film
Intermediate layer 3 made of GdFeCo film having c2 and compensation temperature Tcomp, and TbFe having Curie temperature Tc3 and coercive force Hc3
Recording layer 4 made of Co film and protective layers 5a, 5b made of silicon nitride
The reproducing layer 2 and the recording layer 4 are exchange-coupled via the intermediate layer 3. Each layer is formed by a sputtering method or a vacuum evaporation method, and the thickness of each layer is 40 n
m, the intermediate layer 3 was set to 1 to 10 nm, and the recording layer 4 was set to 50 nm. Curie temperature Tc1 is about 300 ° C,
c2 is 200 ° C., Tc3 is about 300 ° C., coercive force is Hc1 of 1.5 to 2 kOe and Hc3 is rare earth dominant (RE-r at room temperature).
ich) It was set to 5 kOe. The compensation temperature Tcomp of the intermediate layer 3 is about 150 ° C.
【００２２】図中の６は初期化磁界Ｈi、７は再生磁界
Ｈr、８は再生光（斜線部も含む）、９は記録磁区、１
０は初期化磁界で消滅した記録磁区を示す。In the figure, 6 is an initializing magnetic field Hi, 7 is a reproducing magnetic field Hr, 8 is reproducing light (including a shaded portion), 9 is a recording magnetic domain, 1
0 indicates a recording magnetic domain which disappeared by the initializing magnetic field.
【００２３】以上のように構成された光磁気記録媒体に
ついて、以下その動作を説明する。情報は記録層４に記
録磁区９として記録用磁界（３百Ｏｅ前後）の下で熱磁
気記録されている。室温においては、中間層３の交換結
合抑制作用により記録層４から再生層２への記録磁区９
の転写する力、すなわち、交換結合力Ｈ1-3は弱められ
ている。つまり、中間層３の磁化は膜厚が薄いために記
録層４と再生層２からの交換結合力により垂直方向に向
くが、もともと面内に向こうとしている磁化を無理やり
垂直方向に向かせているために、そこに力がとられる。
このため、垂直磁化膜である記録層４と再生層２を直接
に積層するよりは記録層４と再生層２の交換結合力は弱
まる。中間層３の厚みが零のときの交換結合力を基準に
して図３に示した交換結合力から分るように、中間層３
の厚みが３ｎｍのとき、交換結合力は中間層３を挿入し
ないときの６割程度に減らすことができる。中間層３の
ないときの再生層２と記録層４の交換結合力が約１．５
ｋＯｅなので、中間層３の厚みが３ｎｍのとき、Ｈ1-3
は室温で９百Ｏｅ程度まで低減でき、Ｈc1を１．５ｋＯ
ｅ程度とすれば初期化磁界Ｈiを３ｋＯｅ以下に低減し
てもＨc1＞Ｈ1-3、かつ、Ｈc1＋Ｈ1-3＜Ｈi＜Ｈc3の関
係を容易に設定できる。従って、再生層２の磁化は初期
化磁界Ｈiの向きに揃い、記録磁区１０は消滅し、再生
層２には存在しない。再生時に、再生光８の照射によっ
て再生層２の一部分２ａの温度が１５０℃程度以上に上
昇したとき、中間層３の補償温度（１５０℃）付近とな
り、磁化の減少により反磁界が大幅に減少して（磁化が
零で反磁界は零である。）交換結合の抑制作用が小さく
なって交換結合力Ｈ1-3が０．５ｋＯｅ程度に大きくな
るため、Ｈc1＜Ｈ1-3＋Ｈr，Ｈ3-1＋Ｈr＜Ｈc3の関係が
容易に成立できる。従って、再生層２の一部分２ａの磁
化は記録層４の磁化の向きに揃えられるので、記録層４
の記録磁区９は再生層２に転写される。The operation of the magneto-optical recording medium having the above structure will be described below. Information is thermomagnetically recorded on the recording layer 4 as a recording magnetic domain 9 under a recording magnetic field (about 300 Oe). At room temperature, the recording magnetic domain 9 from the recording layer 4 to the reproducing layer 2 is suppressed by the exchange coupling suppressing action of the intermediate layer 3.
The transfer force of, that is, the exchange coupling force H1-3 is weakened. That is, since the magnetization of the intermediate layer 3 is thin, the magnetization is oriented in the vertical direction due to the exchange coupling force from the recording layer 4 and the reproduction layer 2, but the magnetization originally intended to be in-plane is forced to be oriented in the vertical direction. For that, power is taken there.
For this reason, the exchange coupling force between the recording layer 4 and the reproducing layer 2 is weaker than when the recording layer 4 and the reproducing layer 2 which are perpendicularly magnetized films are directly laminated. As can be seen from the exchange coupling force shown in FIG. 3 based on the exchange coupling force when the thickness of the intermediate layer 3 is zero, the intermediate layer 3
When the thickness is 3 nm, the exchange coupling force can be reduced to about 60% of that when the intermediate layer 3 is not inserted. The exchange coupling force between the reproducing layer 2 and the recording layer 4 without the intermediate layer 3 is about 1.5.
Since it is kOe, when the thickness of the intermediate layer 3 is 3 nm, H1-3
Can be reduced to about 900 Oe at room temperature, and Hc1 is 1.5 kO
If it is about e, the relationship of Hc1> H1-3 and Hc1 + H1-3 <Hi <Hc3 can be easily set even if the initialization magnetic field Hi is reduced to 3 kOe or less. Therefore, the magnetization of the reproducing layer 2 is aligned in the direction of the initializing magnetic field Hi, the recording magnetic domain 10 disappears, and the reproducing layer 2 does not exist. During reproduction, when the temperature of the portion 2a of the reproducing layer 2 rises to about 150 ° C. or more due to the irradiation of the reproducing light 8, the temperature becomes close to the compensation temperature (150 ° C.) of the intermediate layer 3, and the demagnetizing field is greatly reduced due to the decrease in magnetization. (The magnetization is zero and the demagnetizing field is zero.) The effect of suppressing the exchange coupling is reduced and the exchange coupling force H1-3 is increased to about 0.5 kOe, so that Hc1 <H1-3 + Hr, H3-1 + Hr < The relationship of Hc3 can be easily established. Therefore, the magnetization of the portion 2a of the reproducing layer 2 is aligned with the magnetization direction of the recording layer 4, so that the recording layer 4
The recording magnetic domain 9 is transferred to the reproducing layer 2.
【００２４】更に、再生層２の一部分２ｂでは温度が２
００℃以上になり、中間層３のキュリー温度Ｔc2の２０
０℃をこえるので、中間層３の一部分１１の磁化が消滅
する。このために、交換結合力Ｈ1-3は零となる。この
ために、再生層２の保磁力Ｈc1はもともと小さいのでＨ
c1＜Ｈr（再生磁界）となり、再生層２の一部分２ｂで
は再び再生層２は再生磁界Ｈrの方向に揃う。このた
め、再生層２の一部分２ａのみで記録層４の記録磁区９
が再生層２に転写される。Further, in the portion 2b of the reproducing layer 2, the temperature is 2
When the temperature exceeds 00 ° C and the Curie temperature Tc2 of the intermediate layer 3 is 20
Since the temperature exceeds 0 ° C., the magnetization of the part 11 of the intermediate layer 3 disappears. Therefore, the exchange coupling force H1-3 becomes zero. Therefore, the coercive force Hc1 of the reproducing layer 2 is originally small, so
c1 <Hr (reproducing magnetic field), and the reproducing layer 2 is aligned again in the direction of the reproducing magnetic field Hr in the part 2b of the reproducing layer 2. Therefore, the recording magnetic domain 9 of the recording layer 4 is formed only in the part 2a of the reproducing layer 2.
Are transferred to the reproduction layer 2.
【００２５】この光磁気記録媒体を再生した場合、再生
光８の照射により光磁気記録媒体の温度が上昇する。集
束された再生光８の強度はガウシアン分布を有し、光磁
気記録媒体が再生光８に対して矢印Ａで示した方向に移
動するので、再生光スポット内の温度分布は再生光８の
中心付近より後方にずれて再生層２の一部分２ａは１５
０℃程度ないし２００℃の高温となり、再生層２の一部
分２ｂは２００℃以上の高温となる。すなわち、再生光
８のうち１５０℃程度以上２００℃以下になった一部分
において交換結合力Ｈ1-3が０．５ｋＯｅ程度に大きく
なり、Ｈc1＜Ｈ1-3＋Ｈr，Ｈ3-1＋Ｈr＜Ｈc3の関係が成
立して、再生層２の一部分２ａの磁化は記録層４の磁化
の向きに揃えられるので、記録層４の記録磁区９は再生
層２に転写される。When this magneto-optical recording medium is reproduced, the temperature of the magneto-optical recording medium rises due to the irradiation of the reproducing light 8. Since the intensity of the focused reproducing light 8 has a Gaussian distribution and the magneto-optical recording medium moves in the direction indicated by the arrow A with respect to the reproducing light 8, the temperature distribution in the reproducing light spot is the center of the reproducing light 8. The part 2a of the reproducing layer 2 is displaced from the vicinity to the rear by 15
The temperature rises from about 0 ° C. to 200 ° C., and the portion 2b of the reproduction layer 2 reaches a high temperature of 200 ° C. or higher. That is, the exchange coupling force H1-3 increases to about 0.5 kOe in a part of the reproduction light 8 where the temperature is 150 ° C. or higher and 200 ° C. or lower, and the relationship of Hc1 <H1-3 + Hr, H3-1 + Hr <Hc3 is established. Then, the magnetization of the portion 2a of the reproducing layer 2 is aligned with the magnetization direction of the recording layer 4, so that the recording magnetic domain 9 of the recording layer 4 is transferred to the reproducing layer 2.
【００２６】また、２００℃以上の高温となる部分２ｂ
では中間層３の磁化が消滅して（中間層の一部分１
１）、交換結合力Ｈ1-3が零となり、再生磁界Ｈrが再生
層２の保磁力Ｈc1より大となり、再び再生層２の磁化は
再生磁界Ｈrの方向に揃う。The portion 2b having a high temperature of 200 ° C. or higher
Then, the magnetization of the intermediate layer 3 disappears (a part of the intermediate layer 1
1) The exchange coupling force H1-3 becomes zero, the reproducing magnetic field Hr becomes larger than the coercive force Hc1 of the reproducing layer 2, and the magnetization of the reproducing layer 2 is aligned in the direction of the reproducing magnetic field Hr again.
【００２７】図４に示すように、室温において、再生層
２の保磁力Ｈc1は１．５ｋＯｅ、磁界換算した交換結合
力Ｈ1-3は０．８ｋＯｅである。Ｈc1＞Ｈ1-3となり３．
５ｋＯｅ程度の初期化磁界Ｈiで初期化できる。温度の
上昇とともに保磁力Ｈc1と交換結合力Ｈ1-3は共に減少
し、温度Ｔo（約１５０℃）で同値となる。この温度Ｔo
以上ではＨc1＞Ｈ1-3となり、記録層４の磁化が再生層
２に転写される。更に温度が上昇してＴc2になると中間
層３の磁化が消滅するために交換結合力Ｈ1-3は零とな
る。As shown in FIG. 4, at room temperature, the coercive force Hc1 of the reproducing layer 2 is 1.5 kOe and the exchange coupling force H1-3 converted into a magnetic field is 0.8 kOe. Hc1> H1-3, 3.
It can be initialized with an initializing magnetic field Hi of about 5 kOe. Both the coercive force Hc1 and the exchange coupling force H1-3 decrease as the temperature rises, and become the same value at the temperature To (about 150 ° C.). This temperature To
In the above, Hc1> H1-3, and the magnetization of the recording layer 4 is transferred to the reproducing layer 2. When the temperature further rises to Tc2, the magnetization of the intermediate layer 3 disappears and the exchange coupling force H1-3 becomes zero.
【００２８】次に、この光磁気記録媒体の再生方法につ
いて説明する。記録磁区９の大きさが０．４μｍで、線
速が５．６ｍ／ｓで、再生パワーが１〜３．５ｍＷの光
磁気記録媒体の再生出力とノイズの再生パワー依存性を
示した図５から分るように、再生パワーが１ｍＷでは再
生出力は低いが、再生パワーの増加にともない光磁気記
録媒体も昇温し、１．５ｍＷで図４で示した温度Ｔo以
上になり記録層４の磁化が再生層２に転写され出力が激
増する。更に再生パワーを上げると一部の領域で中間層
３のキュリー温度Ｔc2を越えるために、図２の再生層２
の一部分２ｂで示した領域が出現し出力が更に増加す
る。つまり再生するときに、１．５ｍＷの再生パワーが
記録層４の磁化の再生層２への転写が開始する光磁気記
録媒体の温度となる。また、出力を更に増加させると中
間層３の一部に中間層３のキュリー温度Ｔc2を越える部
分が出現する。Next, a reproducing method of this magneto-optical recording medium will be described. FIG. 5 shows the reproduction output dependency of noise and the reproduction output of a magneto-optical recording medium having a recording magnetic domain 9 size of 0.4 μm, a linear velocity of 5.6 m / s, and a reproduction power of 1 to 3.5 mW. As can be seen from the above, when the reproducing power is 1 mW, the reproducing output is low, but as the reproducing power increases, the temperature of the magneto-optical recording medium also rises, and at 1.5 mW, the temperature exceeds the temperature To shown in FIG. The magnetization is transferred to the reproducing layer 2 and the output increases sharply. When the reproducing power is further increased, the Curie temperature Tc2 of the intermediate layer 3 is exceeded in a part of the region, so that the reproducing layer 2 of FIG.
The area indicated by a part 2b of 1 appears, and the output further increases. That is, when reproducing, the reproducing power of 1.5 mW becomes the temperature of the magneto-optical recording medium at which the transfer of the magnetization of the recording layer 4 to the reproducing layer 2 starts. Further, when the output is further increased, a part of the intermediate layer 3 that exceeds the Curie temperature Tc2 of the intermediate layer 3 appears.
【００２９】記録層４の磁化の再生層２への転写がおき
ている領域の温度が、中間層３の補償温度Ｔcomp近傍に
設定されているために、記録層４の磁化の再生層２への
転写が容易となる。再生パワーと中間層３の昇温温度の
関係は、光磁気記録媒体が移動する線速や光磁気記録媒
体の構造により変化するため一義的には決まらない。そ
こで、記録磁区９を外部磁界零の条件で消去が開始する
パワーから類推する。この消去開始パワーで記録磁区９
の一部はキュリー温度Ｔc2に達したと推測できるので、
投入するレーザーパワーと記録磁区９が昇温する温度が
比例関係であるとすると、記録磁区９の昇温温度を中間
層３の補償温度Ｔcompにするために必要なパワーが類推
できる。Since the temperature of the region where the magnetization of the recording layer 4 is transferred to the reproducing layer 2 is set near the compensation temperature Tcomp of the intermediate layer 3, the magnetization of the recording layer 4 is transferred to the reproducing layer 2. Transfer becomes easy. The relationship between the reproducing power and the temperature rise temperature of the intermediate layer 3 is not uniquely determined because it changes depending on the linear velocity at which the magneto-optical recording medium moves and the structure of the magneto-optical recording medium. Therefore, the recording magnetic domain 9 is analogized from the power at which erasing is started under the condition that the external magnetic field is zero. With this erasing start power, the recording magnetic domain 9
It can be inferred that a part of has reached the Curie temperature Tc2,
If the supplied laser power and the temperature at which the recording magnetic domain 9 is heated are in a proportional relationship, the power required to raise the temperature at which the recording magnetic domain 9 is raised to the compensation temperature Tcomp of the intermediate layer 3 can be estimated.
【００３０】以上のように本実施例によれば、中間層３
のキュリー温度Ｔc2を低くして再生中に昇温する温度に
近づくと、再生中にキュリー温度Ｔc2以上になる領域が
生じ、そのため磁化がその領域で消滅して、記録層４と
再生層２の相互間の交換結合力が作用しなくなる。これ
は従来の再生補助層の役割であり、本実施例では従来の
再生補助層は必要なくなり、記録層４と再生層２の相互
間の交換結合力を制御すれば良いことになる。従って制
御するパラメータが減少し安定な動作が確保でき、再生
補助層を一つ減らすことによりコストの低減も可能とな
る。更に光磁気記録媒体を構成する各磁性層のキュリー
温度及び保磁力は、組成の選択及び垂直磁気異方性の大
きさを変化させる各種元素の添加によって比較的簡単に
変えることができるので、光磁気記録媒体に要求される
記録再生条件が変化しても最適な光磁気記録媒体を作製
することができる。As described above, according to this embodiment, the intermediate layer 3
When the Curie temperature Tc2 of is decreased to approach the temperature that rises during reproduction, a region having a Curie temperature Tc2 or higher is generated during reproduction, so that the magnetization disappears in that region, and the recording layer 4 and the reproduction layer 2 The exchange coupling force between them does not work. This is the role of the conventional reproduction auxiliary layer. In this embodiment, the conventional reproduction auxiliary layer is not necessary, and the exchange coupling force between the recording layer 4 and the reproduction layer 2 may be controlled. Therefore, the parameters to be controlled are reduced, stable operation can be ensured, and the cost can be reduced by reducing one regeneration assisting layer. Further, the Curie temperature and the coercive force of each magnetic layer constituting the magneto-optical recording medium can be relatively easily changed by selecting the composition and adding various elements that change the magnitude of the perpendicular magnetic anisotropy. An optimum magneto-optical recording medium can be manufactured even if the recording / reproducing conditions required for the magnetic recording medium change.
【００３１】更に、本実施例では記録層４の磁化を再生
層２に転写させながら再生動作を行うため再生中の再生
層２の最高到達温度は記録層４の磁化が再生層２に転写
を開始する温度Ｔo以上になっており、温度Ｔoより大き
くかつキュリー温度Ｔc2より小なる領域において転写が
生じる。また、中間層３の補償温度Ｔcompは記録層４の
磁化が再生層２に転写を開始する温度をＴoとするとＴc
omp＞Ｔoが望ましく、Ｔc2＞Ｔcomp＞Ｔoの関係が成立
すると、再生動作が行われているときに温度Ｔoより大
かつキュリー温度Ｔcより小なる領域において中間層３
の温度は、補償温度Ｔcomp近傍となる。補償温度Ｔcomp
付近では磁化が小さいため反磁界が小さくなり交換結合
力を高める方向に力が働き記録層４の記録磁区９は再生
層２に転写しやすくなるので、動作温度でも交換結合力
が強くなり、記録磁区９の転写性が良くなる。また中間
層３は面内磁化膜であるために室温においては記録層４
と再生層２の交換結合力を弱めるため初期化磁界を低減
できる。Further, in this embodiment, since the reproducing operation is performed while transferring the magnetization of the recording layer 4 to the reproducing layer 2, the maximum temperature reached by the reproducing layer 2 during reproduction is such that the magnetization of the recording layer 4 is transferred to the reproducing layer 2. Transfer occurs in a region which is higher than the starting temperature To and is higher than the temperature To and lower than the Curie temperature Tc2. Further, the compensation temperature Tcomp of the intermediate layer 3 is Tc, where To is the temperature at which the magnetization of the recording layer 4 starts transferring to the reproducing layer 2.
When omp> To is desirable and the relationship of Tc2>Tcomp> To is established, the intermediate layer 3 is in a region which is higher than the temperature To and lower than the Curie temperature Tc during the reproducing operation.
Is near the compensation temperature Tcomp. Compensation temperature Tcomp
In the vicinity, since the magnetization is small, the demagnetizing field becomes small, and a force acts in the direction of increasing the exchange coupling force, and the recording magnetic domain 9 of the recording layer 4 is easily transferred to the reproducing layer 2. Therefore, the exchange coupling force becomes strong even at the operating temperature, and the recording is performed. The transferability of the magnetic domains 9 is improved. Further, since the intermediate layer 3 is an in-plane magnetized film, the recording layer 4 is formed at room temperature.
Since the exchange coupling force of the reproducing layer 2 is weakened, the initializing magnetic field can be reduced.
【００３２】更に、初期化動作及び転写動作を良好に行
うための各磁性膜の組成、交換結合力の制御を簡易に行
え、動作の安定性を広げることができる。Further, the composition of each magnetic film and the exchange coupling force for favorably performing the initialization operation and the transfer operation can be easily controlled, and the stability of the operation can be expanded.
【００３３】なお、中間層３はＧｄＦｅＣｏ膜製とした
が、それ以外の中間層３の補償温度をＴcomp、記録層４
の磁化が再生層２に転写を開始する温度をＴoとしたと
きにＴo＜Ｔcompの条件を満たし、かつ、再生時の昇温
により磁化が喪失する程度のキュリー温度を有する磁性
材料膜製としてもよい。Although the intermediate layer 3 is made of a GdFeCo film, the compensation temperature of the other intermediate layers 3 is Tcomp, and the recording layer 4 is made.
Of the magnetic material film satisfying the condition of To <Tcomp when the temperature at which the magnetization of the layer starts to be transferred to the reproducing layer 2 is To, and having a Curie temperature at which the magnetization is lost due to a temperature rise during reproduction. Good.
【００３４】[0034]
【発明の効果】以上の説明からも明らかなように本発明
は、磁気的に結合した記録層、中間層、再生層を有し、
中間層は室温において面内磁化膜であり、かつ、中間層
の補償温度は記録層の磁化が再生層に転写を開始する温
度よりも高く、かつ、中間層のキュリー温度は再生時の
昇温により磁化が喪失する程度の温度である構成、及
び、その光磁気記録媒体の中間層の一部が中間層のキュ
リー温度に到達し、かつ、中間層の一部の温度が中間層
の補償温度とキュリー温度との間となるような強度のレ
ーザー光で再生する方法により、安定した再生動作が可
能で簡単な構造の優れた光磁気記録媒体及びその再生方
法を実現できるものである。As is apparent from the above description, the present invention has a magnetically coupled recording layer, intermediate layer and reproducing layer,
The intermediate layer is an in-plane magnetized film at room temperature, the compensation temperature of the intermediate layer is higher than the temperature at which the magnetization of the recording layer starts transferring to the reproducing layer, and the Curie temperature of the intermediate layer is the temperature rise during reproduction. The temperature is such that the magnetization is lost due to, and a part of the intermediate layer of the magneto-optical recording medium reaches the Curie temperature of the intermediate layer, and the temperature of a part of the intermediate layer is the compensation temperature of the intermediate layer. It is possible to realize a magneto-optical recording medium having a simple structure capable of stable reproducing operation and a reproducing method thereof by a reproducing method using a laser beam having an intensity that is between the Curie temperature and the Curie temperature.
【図１】本発明の一実施例の光磁気記録媒体の断面略図FIG. 1 is a schematic sectional view of a magneto-optical recording medium according to an embodiment of the present invention.
【図２】（ａ）は同光磁気記録媒体の再生動作を説明す
る平面略図 （ｂ）は（ａ）の要部断面図2A is a schematic plan view for explaining a reproducing operation of the magneto-optical recording medium, and FIG. 2B is a cross-sectional view of a main part of FIG.
【図３】同光磁気記録媒体の中間層の膜厚と交換結合力
の関係を示した図FIG. 3 is a diagram showing a relationship between a film thickness of an intermediate layer of the magneto-optical recording medium and an exchange coupling force.
【図４】同光磁気記録媒体の交換結合力と再生層の保磁
力の温度依存性を示した図FIG. 4 is a diagram showing the temperature dependence of the exchange coupling force of the magneto-optical recording medium and the coercive force of the reproducing layer.
【図５】同光磁気記録媒体の再生出力とノイズの再生パ
ワー依存性を示した図FIG. 5 is a diagram showing reproduction output dependence of the magneto-optical recording medium and reproduction power dependence of noise.
【図６】（ａ）は従来の光磁気記録媒体の再生動作を説
明する平面略図 （ｂ）は（ａ）の要部断面図6A is a schematic plan view for explaining a reproducing operation of a conventional magneto-optical recording medium, and FIG. 6B is a cross-sectional view of a main part of FIG.
２ 再生層 ３ 中間層 ４ 記録層 2 playback layer 3 intermediate layer 4 recording layer
Claims (2)
層を有し、前記記録層に対し信号の記録を行うととも
に、前記再生層の磁化の向きを揃えた後、前記再生層を
レーザー光の照射により昇温せしめ、前記記録層に記録
された磁気信号を前記再生層に転写しながら磁気光学効
果により光学信号に変換して読み取る再生方法で使用す
る光磁気記録媒体であって、前記中間層は室温において
面内磁化膜であり、かつ、前記中間層の補償温度は前記
記録層の磁化が前記再生層に転写を開始する温度よりも
高く、かつ、前記中間層のキュリー温度は再生時の昇温
により磁化が喪失する程度の温度であることを特徴とし
た光磁気記録媒体。1. A recording layer, an intermediate layer, and a reproducing layer which are magnetically coupled to each other, and a signal is recorded in the recording layer, and the reproducing layer is aligned after the magnetization directions of the reproducing layer are aligned. A magneto-optical recording medium used in a reproducing method which is heated by irradiation of laser light and is converted into an optical signal by a magneto-optical effect while reading the magnetic signal recorded in the recording layer onto the reproducing layer, The intermediate layer is an in-plane magnetized film at room temperature, the compensation temperature of the intermediate layer is higher than the temperature at which the magnetization of the recording layer starts transferring to the reproducing layer, and the Curie temperature of the intermediate layer is A magneto-optical recording medium characterized in that the temperature is such that the magnetization is lost by the temperature rise during reproduction.
層を有し、前記中間層は室温において面内磁化膜であ
り、かつ、前記中間層の補償温度が前記記録層の磁化が
前記再生層に転写を開始する温度より高く、かつ、再生
時の昇温により前記中間層の磁化が喪失する程度の温度
のキュリー温度を有する光磁気記録媒体を前記中間層の
一部の温度がキュリー温度に到達し、かつ、前記中間層
の一部の温度が前記中間層の補償温度とキュリー温度と
の間になるような強度のレーザー光で再生することを特
徴とした光磁気記録媒体の再生方法。2. A magnetically coupled recording layer, an intermediate layer, and a reproducing layer, wherein the intermediate layer is an in-plane magnetized film at room temperature, and the compensation temperature of the intermediate layer is the magnetization of the recording layer. A magneto-optical recording medium having a Curie temperature higher than the temperature at which transfer is started to the reproducing layer and at a temperature at which the magnetization of the intermediate layer is lost due to a temperature increase during reproduction is used. A magneto-optical recording medium is characterized in that reproduction is performed with a laser beam having an intensity that reaches the Curie temperature and a temperature of a part of the intermediate layer is between the compensation temperature of the intermediate layer and the Curie temperature. How to play.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15470293A JPH0714230A (en) | 1993-06-25 | 1993-06-25 | Magneto-optical recording medium and its reproduction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15470293A JPH0714230A (en) | 1993-06-25 | 1993-06-25 | Magneto-optical recording medium and its reproduction method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0714230A true JPH0714230A (en) | 1995-01-17 |
Family
ID=15590089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15470293A Pending JPH0714230A (en) | 1993-06-25 | 1993-06-25 | Magneto-optical recording medium and its reproduction method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0714230A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6020079A (en) * | 1994-01-17 | 2000-02-01 | Fujitsu Limited | Magneto-optical recording medium and reproducing method for information recorded on the medium |
| WO2002065465A1 (en) * | 2001-02-14 | 2002-08-22 | Fujitsu Limited | Magnetooptic recording medium |
| US6800348B2 (en) | 1998-06-04 | 2004-10-05 | Sony Corporation | Optical recording medium |
-
1993
- 1993-06-25 JP JP15470293A patent/JPH0714230A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6020079A (en) * | 1994-01-17 | 2000-02-01 | Fujitsu Limited | Magneto-optical recording medium and reproducing method for information recorded on the medium |
| US6128254A (en) * | 1994-01-17 | 2000-10-03 | Fujitsu Limited | Magneto-optical recording medium and reproducing method for information recorded on the medium |
| US6800348B2 (en) | 1998-06-04 | 2004-10-05 | Sony Corporation | Optical recording medium |
| WO2002065465A1 (en) * | 2001-02-14 | 2002-08-22 | Fujitsu Limited | Magnetooptic recording medium |
| US6844083B2 (en) | 2001-02-14 | 2005-01-18 | Fujitsu Limited | Magneto-optical recording medium possessing a magnetic assist layer |
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