JPH0614416B2 - Magneto-optical recording / reproducing method - Google Patents
Magneto-optical recording / reproducing methodInfo
- Publication number
- JPH0614416B2 JPH0614416B2 JP58045374A JP4537483A JPH0614416B2 JP H0614416 B2 JPH0614416 B2 JP H0614416B2 JP 58045374 A JP58045374 A JP 58045374A JP 4537483 A JP4537483 A JP 4537483A JP H0614416 B2 JPH0614416 B2 JP H0614416B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- magnetic thin
- amorphous magnetic
- magneto
- information
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
- G11B11/10586—Record carriers characterised by the selection of the material or by the structure or form characterised by the selection of the material
Description
【発明の詳細な説明】 (イ) 産業上の利用分野 本発明は、レーザ光に依って情報の記録再生が行われる
アモルファス磁性薄膜から成る光磁気記録再生方法に関
する。The present invention relates to a magneto-optical recording / reproducing method comprising an amorphous magnetic thin film for recording / reproducing information by laser light.
(ロ) 従来技術 直線偏光が磁性体表面で反射したり、磁性体を透過する
際に偏光面が回転する現象を利用して、光による磁気記
録情報の読み出しの応用が試みられている。このような
光磁気記録媒体としては情報記録の高密度化、また磁気
カ一効果を利用して記録情報の読み出しを行う場合、磁
気カ一効果が大きくなること等から磁性体膜面に垂直な
方向に磁化容易軸を有した垂直磁化膜を備えた光磁気記
録媒体が一般にに用いられている。この光磁気記録媒体
への情報の書込みは、通常磁気記録層をあらかじめ同一
方向に一様に垂直磁化し、この磁気記録媒体をキュリー
点又は補償点までレーザ光等によって加熱し、前記磁化
方向と逆方向の小さな磁場を印加して、レーザ光等によ
る加熱領域の磁化を反転させるという方法が用いられ
る。記録情報の読み出しは前述の偏光回転の原理を利用
し、磁性薄膜からの偏光の戻り光の回転角を検出するこ
とによって行う。このような磁気記録媒体としては高保
磁力で垂直磁気異方性を有するMn−Bi、Gd−Fe、Tb−Fe
等の希土類−遷移金属系のアモルファス合金の磁性薄膜
が用いられる。磁気記録媒体の中で、Mn−Bi合金や、Gd
−Fe合金等の磁気記録媒体はカー回転角が大きく再生時
のＳ／Ｎが大であるが、キュリー点が高く、情報書込み
に要するエネルギーが大という欠点があり、一方、Tb−
Fe合金やDy−Fe合金等はキュリー点がMn−Bi合金やGd−
Fe合金より低く、情報書込みに要するエネルギーが小で
あるが、カー回転角が小さくＳ／Ｎが小さいという互い
に相反する長所と短所を有している。また、一般にカー
回転角は非常に小さいもので、大きなものでもたかだか
１゜程度のものであり、記録情報再生にあたってはカー
回転角を大きくすることが大きな問題点となっている。(B) Conventional Technology An application of reading magnetically recorded information by light has been attempted by utilizing the phenomenon that linearly polarized light is reflected on the surface of a magnetic material, or the plane of polarization is rotated when passing through the magnetic material. As such a magneto-optical recording medium, when the density of information recording is increased, and when the recorded information is read by utilizing the magnetic effect, the magnetic effect is increased, so that it is perpendicular to the magnetic film surface. A magneto-optical recording medium provided with a perpendicular magnetization film having an easy axis of magnetization in the direction is generally used. To write information on this magneto-optical recording medium, normally, the magnetic recording layer is uniformly magnetized perpendicularly in advance in the same direction, and the magnetic recording medium is heated to a Curie point or a compensation point by laser light or the like to change the magnetization direction to the above-mentioned magnetization direction. A method of applying a small magnetic field in the opposite direction to invert the magnetization of the heating region by laser light or the like is used. The recorded information is read by utilizing the above-described principle of polarization rotation and detecting the rotation angle of the polarized light returning from the magnetic thin film. Such magnetic recording media include Mn-Bi, Gd-Fe, and Tb-Fe with high coercive force and perpendicular magnetic anisotropy.
A magnetic thin film of a rare earth-transition metal-based amorphous alloy such as is used. Among magnetic recording media, Mn-Bi alloy and Gd
Magnetic recording media such as Fe alloys have a large Kerr rotation angle and a large S / N ratio at the time of reproduction, but have the disadvantages of high Curie point and large energy required for writing information.
The Curie points of Fe alloys and Dy-Fe alloys are Mn-Bi alloys and Gd-
It is lower than the Fe alloy and requires less energy to write information, but has opposite advantages and disadvantages that the Kerr rotation angle is small and the S / N is small. Further, generally, the Kerr rotation angle is very small, and even a large Kerr rotation angle is about 1 °, and it is a big problem to increase the Kerr rotation angle in reproducing recorded information.
(ハ) 発明の目的 本発明は以上の点を改善し、低エネルギーで情報書込み
ができ、再生時のカー回転角を大きくしてＳ／Ｎの大き
な光磁気記録再生方法を提供する事を目的としている。(C) Object of the present invention It is an object of the present invention to provide a magneto-optical recording / reproducing method that improves the above points, enables information writing with low energy, and increases the Kerr rotation angle at the time of reproduction and has a large S / N. I am trying.
(ニ) 発明の構成 本発明は、低保磁力で光磁気効果の大きな第１の磁性薄
膜と高保磁力でキュリー点が低く垂直磁気異方性のある
第２の磁性薄膜とを積層した媒体に対し、第２の磁性薄
膜に光磁気記録を為し、磁気転写により第１の磁性薄膜
を磁化し、第２の磁性薄膜側より読み取りを実行するこ
とを特徴とする。(D) Structure of the Invention The present invention provides a medium in which a first magnetic thin film having a low coercive force and a large magneto-optical effect and a second magnetic thin film having a high coercive force and a low Curie point and perpendicular magnetic anisotropy are laminated. On the other hand, magneto-optical recording is performed on the second magnetic thin film, the first magnetic thin film is magnetized by magnetic transfer, and reading is performed from the second magnetic thin film side.
(ホ) 実施例 第１図は本発明に採用する光磁気記録媒体の一実施例を
模型的に示した断面図であって、(1)はガラス等の非磁
性体の基板、(2)は該基板(1)上に蒸着或いはスパタリン
グ法等に依って形成された第１のアモルファス磁性薄膜
で、低保磁力で磁気光学効果は大きいがキュリー点が高
い垂直磁気異方性を有するGd−Fe合金、Mn−Bi合金等か
ら成り、その厚みは1000Å程度である。(3)はこの第１
のアモルファス磁性薄膜(2)上に蒸着或いはスパタリン
グ法等に依って形成された第２のアモルファス磁性薄膜
で、高保持力でキュリー点は低いが磁気光学効果が低い
垂直磁気異方性を有するTb−Fe合金、Dy−Fe合金等から
成り、その厚みは500Å程度である。(4)はこの第２のア
モルファス磁性薄膜(3)表面に設けられた酸化シリコン
膜等の保護膜である。斯る構成の記録媒体(5)に情報を
書き込む際の構成を第２図に示す。記録媒体(5)を所定
の磁場(6)に置くと共に情報書き込みエリアにレーザ光
(7)を照射する。その結果、レーザ光(7)の照射を受けた
箇所が温度上昇し、キュリー点が低い第２のアモルファ
ス磁性薄膜(3)の保磁力が低下して外部磁場(6)に依って
磁化方向が反転(8)する。この第２のアモルファス磁性
薄膜(3)は高保磁力である為に書き込まれた情報は安定
に保持され、そして磁化方向が反転したエリア(8)の真
下に位置する第１のアモルファス磁性薄膜(2)の磁区が
その反転エリア(8)の磁界に依って反転し、情報が記録
(9)される（第３図）。この書き込み時に要するエネル
ギーはレーザ光(7)が照射される第２のアモルファス磁
性薄膜(3)が低キュリー点を有しているで小さくて済
み、また保磁力の小さなGd−Fe合金薄膜等では問題とな
る書き込みビットの不安定性も二層構造を採る事に依り
解消され、書き込ままれた情報は安定に保持される。こ
のようにして書き込まれた情報を読み出出す際の構成を
第４図に示す。(10)は読み出しレーザ光源で、書き込み
時に使用したレーザ光(7)よりはは弱い光を出す。該レ
ーザ光源(10)からのレーザ光は偏光子(11)にて直線偏光
とされ、ハーフミラー(12)及びレンズ(13)を介して記録
媒体(5)に到達する。記録媒体(5)に達した直線偏光は第
２のアモルファス磁性薄膜(3)の表面にて反射する光と
透過する光とに分れる。反射光はカー効果に依って偏光
面が回転し、透過光も一般にカー効果に依る偏光面の回
転より回転角の大きいファラデー効果に依り偏光面が回
転する。一方、透過光は更に、磁気光学効果の大きい第
１のアモルファス磁性薄膜(2)表面で反射する際のカー
効果、戻り光の磁性薄膜透過に依るファラデー効果に依
り、回転角は増し、みかけ上、回転角は増加する事とな
る。磁性薄膜はその組成を選択することに依ってカー回
転角の回転方向を選ぶことができるので作成時に磁性薄
膜の組成を適当に選べば、回転角が増加する方向に持っ
ていくことができる。透過光も利用するため第２のアモ
ルファス磁性薄膜(3)の厚みを垂直磁化となる範囲で薄
くし、透過を大きくすることが必要である。このように
該磁性薄膜(3)の反射光と、透過による戻り光のたしあ
わせでみかけ上の偏光回転量は大きくなり、磁気記録媒
体(5)からのかえり光を検光子(14)を介して偏光面の回
転量の変化を検出し、その検出量を光電変換素子(15)に
より電気信号に変換し、記録情報を再生することができ
る。みかけ上の偏光面の回転量が大きいため電気信号の
変化も大きいものとなる。(E) Embodiment FIG. 1 is a schematic sectional view showing an embodiment of a magneto-optical recording medium adopted in the present invention, (1) is a non-magnetic substrate such as glass, and (2) Is a first amorphous magnetic thin film formed on the substrate (1) by vapor deposition or sputtering, and has a low coercive force, a large magneto-optical effect, and a perpendicular magnetic anisotropy with a high Curie point. It consists of Fe alloy, Mn-Bi alloy, etc., and its thickness is about 1000Å. (3) is this first
A second amorphous magnetic thin film formed by vapor deposition or sputtering on the amorphous magnetic thin film (2) of Tb, which has a high coercive force and a low Curie point but a low magneto-optical effect and a perpendicular magnetic anisotropy. -Fe alloy, Dy-Fe alloy, etc., and its thickness is about 500Å. (4) is a protective film such as a silicon oxide film provided on the surface of the second amorphous magnetic thin film (3). FIG. 2 shows a structure for writing information on the recording medium (5) having such a structure. Place the recording medium (5) in the specified magnetic field (6) and laser light in the information writing area.
Irradiate (7). As a result, the temperature of the portion irradiated with the laser beam (7) rises, the coercive force of the second amorphous magnetic thin film (3) having a low Curie point is lowered, and the magnetization direction is changed by the external magnetic field (6). Invert (8). Since the second amorphous magnetic thin film (3) has a high coercive force, the written information is stably held, and the first amorphous magnetic thin film (2) located directly below the area (8) in which the magnetization direction is reversed. ) Domain is inverted by the magnetic field of the inversion area (8), and information is recorded.
(9) is performed (Fig. 3). The energy required for this writing is small because the second amorphous magnetic thin film (3) irradiated with the laser beam (7) has a low Curie point, and is small for a Gd-Fe alloy thin film with a small coercive force. The problematic instability of the write bit is eliminated by adopting a two-layer structure, and the written information is held stable. FIG. 4 shows a configuration for reading out the information thus written. A reading laser light source (10) emits light weaker than the laser light (7) used for writing. The laser light from the laser light source (10) is linearly polarized by the polarizer (11) and reaches the recording medium (5) via the half mirror (12) and the lens (13). The linearly polarized light reaching the recording medium (5) is divided into light reflected on the surface of the second amorphous magnetic thin film (3) and light transmitted therethrough. The plane of polarization of the reflected light rotates due to the Kerr effect, and the plane of polarization of the transmitted light also rotates due to the Faraday effect having a larger rotation angle than the rotation of the plane of polarization due to the Kerr effect. On the other hand, the transmitted light further increases the rotation angle due to the Kerr effect when reflected on the surface of the first amorphous magnetic thin film (2), which has a large magneto-optical effect, and the Faraday effect due to the return of the magnetic thin film through the magnetic thin film, resulting in an apparent increase in rotation angle. , The rotation angle will increase. The rotation direction of the Kerr rotation angle can be selected by selecting the composition of the magnetic thin film. Therefore, if the composition of the magnetic thin film is properly selected at the time of preparation, the rotation angle can be increased. Since the transmitted light is also used, it is necessary to reduce the thickness of the second amorphous magnetic thin film (3) in the range of perpendicular magnetization to increase the transmission. In this way, the apparent polarization rotation amount increases due to the addition of the reflected light of the magnetic thin film (3) and the returned light due to transmission, and the return light from the magnetic recording medium (5) is passed through the analyzer (14). Thus, the change in the rotation amount of the polarization plane is detected, the detected amount is converted into an electric signal by the photoelectric conversion element (15), and the recorded information can be reproduced. Since the apparent amount of rotation of the polarization plane is large, the change in the electric signal is also large.
(ヘ) 発明の効果 以上のように、本発明は、低保磁力で磁気光学効果の大
きい垂直磁性薄膜の上に高保磁力でキュリー点の低い垂
直磁性薄膜を形成した二層膜構造にし、キュリー点の低
い磁性薄膜側からレーザ光にて情報を書き込むことによ
り、低エネルギーで情報を書き込むことができ、かつ、
記録情報（書込みビット）の安定性が高く、また、再生
においては偏光の回転量が大きく、大きな信号変化量が
得られる。(F) Effects of the Invention As described above, the present invention has a two-layer film structure in which a perpendicular magnetic thin film having a high coercive force and a low Curie point is formed on a perpendicular magnetic thin film having a low coercive force and a large magneto-optical effect. By writing information with a laser beam from the side of the magnetic thin film having a low point, information can be written with low energy, and
The stability of the recorded information (written bit) is high, and the amount of polarization rotation is large during reproduction, so that a large amount of signal change can be obtained.
第１図は本発明に採用する光磁気記録媒体の一実施例を
模型的に示した断面図、第２図は情報書込みの際の原理
を説明する概念図、第３図は情報が記録された状態を示
す断面図、第４図は記録情報の読み出しの際の構成を示
す構成図であって、(2)(3)は第１、第２のアモルファス
磁性薄膜、(5)は磁気記録媒体、(6)は磁場、(7)はレー
ザ光、を夫々示している。FIG. 1 is a cross-sectional view schematically showing an embodiment of a magneto-optical recording medium adopted in the present invention, FIG. 2 is a conceptual diagram explaining the principle at the time of writing information, and FIG. 3 is recording information. FIG. 4 is a sectional view showing a state in which the recorded information is read out, and FIG. 4 is a configuration diagram showing a configuration at the time of reading recorded information. (2) and (3) are first and second amorphous magnetic thin films, and (5) is magnetic recording. The medium, (6) shows a magnetic field, and (7) shows a laser beam.
Claims (1)
磁気光効果の大きな垂直磁気異方性を有する第１のアモ
ルファス磁性薄膜と、該薄膜上に形成した高保持力でキ
ュリー点の低い垂直磁気異方性を有する第２のアモルフ
ァス磁性薄膜とから成る光磁気記録媒体に対し、所定の
磁場をかけた状態で前記第２のアモルファス磁性薄膜側
からレーザ光を照射して前記第２のアモルファス磁性薄
膜に情報を磁気的に記録し、前記第２のアモルファス磁
性薄膜の記録情報を前記第１のアモルファス磁性薄膜に
磁気転写せしめ、記録済記録媒体に対して前記第２のア
モルファス磁性薄膜側から偏光を照射し、前記第２のア
モルファス磁性薄膜の表面にて反射される反射光と前記
第２のアモルファス磁性薄膜を透過して前記第１のアモ
ルファス磁性薄膜の表面に達して反射される反射光とよ
りなる戻り光の偏光面の回転量の変化に基づいて記録情
報を再生する光磁気記録再生方法。1. A first amorphous magnetic thin film having a low coercive force formed on a substrate surface of a non-magnetic material and having a perpendicular magnetic anisotropy having a large magneto-optical effect, and a high coercive force formed on the thin film, and a Curie point. Of a second amorphous magnetic thin film having a low perpendicular magnetic anisotropy, a laser beam is irradiated from the second amorphous magnetic thin film side in a state where a predetermined magnetic field is applied to the magneto-optical recording medium. Information is magnetically recorded on the second amorphous magnetic thin film, the recording information on the second amorphous magnetic thin film is magnetically transferred to the first amorphous magnetic thin film, and the second amorphous magnetic is recorded on the recorded recording medium. The first amorphous magnetic thin film is irradiated with polarized light from the thin film side, is reflected by the surface of the second amorphous magnetic thin film, and is transmitted through the second amorphous magnetic thin film. Magneto-optical recording and reproducing method for reproducing recorded information based on the rotation amount of the change of the polarization plane of the more becomes the return light and the reflected light reflected reaches the surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58045374A JPH0614416B2 (en) | 1983-03-17 | 1983-03-17 | Magneto-optical recording / reproducing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58045374A JPH0614416B2 (en) | 1983-03-17 | 1983-03-17 | Magneto-optical recording / reproducing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59168954A JPS59168954A (en) | 1984-09-22 |
| JPH0614416B2 true JPH0614416B2 (en) | 1994-02-23 |
Family
ID=12717488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58045374A Expired - Lifetime JPH0614416B2 (en) | 1983-03-17 | 1983-03-17 | Magneto-optical recording / reproducing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0614416B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2588406B1 (en) * | 1985-10-04 | 1994-03-25 | Thomson Csf | THERMOMAGNETIC RECORDING HEAD AND METHOD FOR PRODUCING THE SAME |
| JPS6314342A (en) * | 1986-07-05 | 1988-01-21 | Canon Inc | Magneto-optical recording medium |
| JPH06309710A (en) * | 1993-04-27 | 1994-11-04 | Nikon Corp | Magneto-optical recording medium |
| US6630667B1 (en) * | 2000-09-29 | 2003-10-07 | Nptest, Llc | Compact, high collection efficiency scintillator for secondary electron detection |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5424008A (en) * | 1977-07-26 | 1979-02-23 | Fujitsu Ltd | Magnetic recording and photo reproducing system |
| JPS57189362A (en) * | 1981-05-13 | 1982-11-20 | Nippon Columbia Co Ltd | Magnetic recording and reproducing device |
| JPS58153244A (en) * | 1982-03-05 | 1983-09-12 | Matsushita Electric Ind Co Ltd | Photomagnetic recording medium |
-
1983
- 1983-03-17 JP JP58045374A patent/JPH0614416B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59168954A (en) | 1984-09-22 |
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