JPH0263262B2 - - Google Patents
Info
- Publication number
- JPH0263262B2 JPH0263262B2 JP56104071A JP10407181A JPH0263262B2 JP H0263262 B2 JPH0263262 B2 JP H0263262B2 JP 56104071 A JP56104071 A JP 56104071A JP 10407181 A JP10407181 A JP 10407181A JP H0263262 B2 JPH0263262 B2 JP H0263262B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- film
- rotation angle
- amorphous thin
- kerr rotation
- 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
- 239000010408 film Substances 0.000 claims description 23
- 239000010409 thin film Substances 0.000 claims description 22
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 229910052723 transition metal Inorganic materials 0.000 claims description 3
- 230000005415 magnetization Effects 0.000 claims description 2
- 239000000758 substrate Substances 0.000 description 8
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 239000000428 dust Substances 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 3
- 230000005374 Kerr effect Effects 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 229910004541 SiN Inorganic materials 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
Description
【発明の詳細な説明】
本発明はレーザ光により情報の記録・再生・消
去を行う磁気光学記憶素子に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical storage element that records, reproduces and erases information using laser light.
近年、高密度・大容量・高速アクセス等種々の
要求を満足し得る光メモリ装置の研究開発が活発
に推進されている。 In recent years, research and development of optical memory devices that can satisfy various demands such as high density, large capacity, and high speed access have been actively promoted.
そして既に実用化に達したものとして、記憶デ
イスクに微細ピツト列を形成し各ピツト部におけ
る光ビームの回折現象を利用して再生信号を得る
装置、及び記憶媒体の反射率変化を利用して再生
信号を得る装置がある。しかしながらこれらの装
置は再生専用であるか又は再生及び情報の追加記
憶が可能なものに留まり、不要な情報を消去し再
記憶可能なものについては未だ研究開発段階にあ
る。 One device that has already been put into practical use is a device that forms a row of fine pits on a storage disk and uses the diffraction phenomenon of a light beam at each pit portion to obtain a reproduction signal, and a device that uses changes in the reflectance of the storage medium to reproduce data. There is a device to get the signal. However, these devices are only for reproduction or capable of reproduction and additional storage of information, and devices capable of erasing unnecessary information and re-storing are still at the research and development stage.
本発明は上記した、記憶した情報を消去し新し
い情報を再記憶出来る素子として期待される、記
憶材料として希土類−遷移金属の非晶質薄膜を用
いた磁気光学記憶素子に関するものである。 The present invention relates to the above-mentioned magneto-optical memory element using an amorphous thin film of rare earth-transition metal as a memory material, which is expected to be an element capable of erasing stored information and re-storing new information.
次に磁気光学記憶素子の従来問題点について説
明する。 Next, conventional problems with magneto-optical storage elements will be explained.
磁気光学記憶素子は上記の利点を有する一方で
再生信号レベルが低いという欠点がある。特に磁
気光学記憶素子からの反射光を利用して情報の再
生を行う所謂カー効果再生方式においてはカー回
転角が小さいため信号雑音比（Ｓ／Ｎ）を高める
事が困難であつた。その為従来では記憶媒体であ
る磁性材料を改良したり或いは記憶媒体上にSiO
やSiO2の誘電体薄膜を形成したりしてカー回転
角を高める工夫がなされれていた。後者の例とし
て例えばTbFeの磁性体薄膜上にSiO膜を形成す
ることによつてカー回転角が0.15度から0.6度に
増大した例が報告されている（IEEE Trans on
Mag Vol−16 No5 1980 P1194）。しかしながら
上記SiOやSiO2の誘電体薄膜では、磁性体に腐蝕
の恐れのある場合はその腐蝕の実質的な防御とは
なり得なく、又1μm程度の小さなほこりやゴミが
該誘電体薄膜に付着した場合は記録ビツト径が
1μm程度であるためビツト検出が不可能になり、
よつて上記SiO、SiO2の誘電体薄膜を形成するこ
とは実用に適さなかつた。そして前記腐蝕の防御
及びほこりやゴミに対する対策の為には0.5〜２
mm程度のガラス又は透明樹脂を磁性体に被覆する
ことが望ましいとされている。しかしこの被覆材
では当然ながらカー回転角の増大は難しく従つて
Ｓ／Ｎの増大の効果を得ることも困難である。 Although the magneto-optical storage element has the above-mentioned advantages, it has the disadvantage that the reproduced signal level is low. In particular, in the so-called Kerr effect reproduction method in which information is reproduced using reflected light from a magneto-optical storage element, it is difficult to increase the signal-to-noise ratio (S/N) because the Kerr rotation angle is small. For this reason, conventional methods have been to improve the magnetic material used as the storage medium, or to add SiO2 to the storage medium.
Efforts have been made to increase the Kerr rotation angle by forming dielectric thin films of SiO 2 and SiO 2 . As an example of the latter, it has been reported that the Kerr rotation angle increased from 0.15 degrees to 0.6 degrees by forming a SiO film on a magnetic thin film of TbFe (IEEE Trans on
Mag Vol−16 No5 1980 P1194). However, the SiO or SiO 2 dielectric thin film described above cannot provide substantial protection against corrosion if there is a risk of corrosion in the magnetic material, and dust and dirt as small as 1 μm may adhere to the dielectric thin film. In this case, the recording bit diameter is
Since it is about 1 μm, bit detection becomes impossible.
Therefore, forming the dielectric thin film of SiO or SiO 2 described above is not suitable for practical use. And for the prevention of corrosion and measures against dust and dirt, 0.5 to 2
It is considered desirable to coat the magnetic material with glass or transparent resin of about mm. However, with this covering material, it is naturally difficult to increase the Kerr rotation angle, and therefore it is also difficult to obtain the effect of increasing the S/N ratio.
本発明は以上の従来点に鑑みなされたものであ
り、カー回転角を増大せしめしかも充分に実用に
適する手段を提供することを目的とする。 The present invention has been made in view of the above-mentioned conventional points, and it is an object of the present invention to provide a means for increasing the Kerr rotation angle and which is fully suitable for practical use.
以下、本発明に係わる磁気光学記憶素子の一実
施例を図面を用いて詳細に説明する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magneto-optical memory element according to the present invention will be described in detail below with reference to the drawings.
第１図は本発明に係わる磁気光学記憶素子の一
実施例の側面断面図である。同図で１はガラス、
アクリル樹脂等の基板であり厚さは0.5〜２mm程
度である。２はGdTbFe、TbDyFe、GdDyFe等
の膜面に垂直な磁化容易軸を有する希土類−遷移
金属非晶質薄膜である。３はAu，Ag，Cu等、そ
の屈折率の実数部が１以下で虚数部が−３乃至−
４の反射膜である。基板１側から入射した入射光
は上記非晶質薄膜２の表面で反射され、かつ上記
非晶質薄膜２を通り上記反射膜３で反射される。
その為に上記二種の反射光が合成されることにな
りカー効果とフアラデー効果が加わり、見かけの
カー回転角は上記反射膜３が存在しない場合に比
べて極めて大きなものが得られる。そしてその結
果としてこの磁気光学記憶素子にレーザ光を照射
して得られる情報のＳ／Ｎは向上する。 FIG. 1 is a side cross-sectional view of one embodiment of a magneto-optical memory element according to the present invention. In the same figure, 1 is glass,
The substrate is made of acrylic resin or the like and has a thickness of about 0.5 to 2 mm. 2 is a rare earth-transition metal amorphous thin film having an axis of easy magnetization perpendicular to the film surface, such as GdTbFe, TbDyFe, or GdDyFe. 3 is Au, Ag, Cu, etc., where the real part of the refractive index is 1 or less and the imaginary part is -3 to -
4 reflective film. Incident light incident from the substrate 1 side is reflected by the surface of the amorphous thin film 2, passes through the amorphous thin film 2, and is reflected by the reflective film 3.
Therefore, the two types of reflected light are combined, and the Kerr effect and Faraday effect are added, resulting in an apparent Kerr rotation angle that is extremely large compared to the case where the reflective film 3 is not present. As a result, the S/N of information obtained by irradiating this magneto-optic storage element with laser light is improved.
上記カー回転角の増大率は、使用するレーザ光
の波長、上記非晶質薄膜２の種類、該非晶質薄膜
２の膜厚及び上記反射膜３の種類によつて変化す
る。 The rate of increase in the Kerr rotation angle changes depending on the wavelength of the laser beam used, the type of the amorphous thin film 2, the thickness of the amorphous thin film 2, and the type of the reflective film 3.
第２図はGdTbFe非晶質薄膜２の膜厚とカー回
転角との関係を、各種反射膜に関して示してい
る。但し使用したレーザの波長は6328Åである。
同図において示されるカー回転角の値は、反射膜
の無い場合のGdTbFe非晶質薄膜のカー回転角が
0.27゜であることを考えればかなり大きく、反射
膜を備えた場合の優位性を表わしている。又、同
図では反射膜として膜厚の充分厚いAg、Au、
Cu、Alを用いた。Ag、Au、Cuを用いた場合は
Alを用いた場合に比較してカー回転角が大きく
しかも互いに略同等の特性となる。これは反射膜
の屈折率の値の相違による現象である。 FIG. 2 shows the relationship between the thickness of the GdTbFe amorphous thin film 2 and the Kerr rotation angle for various reflective films. However, the wavelength of the laser used was 6328 Å.
The value of the Kerr rotation angle shown in the same figure is the Kerr rotation angle of the GdTbFe amorphous thin film without a reflective film.
Considering that it is 0.27°, this is quite large and shows the superiority of the case with a reflective film. In addition, in the same figure, sufficiently thick Ag, Au,
Cu and Al were used. When using Ag, Au, Cu
The Kerr rotation angle is larger than when Al is used, and the properties are approximately the same. This is a phenomenon caused by the difference in the refractive index values of the reflective films.
即ち、使用レーザの波長6328Åに於けるAlの
屈折率は1.6−5.4i、Agの屈折率は0.18−3.3i、Au
の屈折率は0.35−3.16iCuの折率は0.62−3.6iであ
り、Ag、Au、Cuの屈折率は比較的近く、Alの
屈折率のみが離れた値を有する。この為、
GdTbFe非晶質薄膜の膜厚が第２図に示すとおり
膜厚が100Å乃至250Åの間で、Ag、Au、Cuのい
ずれかの反射膜を設けた場合カー回転角は非常に
大きく、上記非晶質薄膜の膜厚が150Å近傍でカ
ー回転角は極大値をとる。しかし、Alの反射膜
を設けた場合はカー回転角は小さい。 That is, at the wavelength of the laser used at 6328 Å, the refractive index of Al is 1.6-5.4i, the refractive index of Ag is 0.18-3.3i, and that of Au is 1.6-5.4i.
The refractive index of Cu is 0.35-3.16i, and the refractive index of Ag, Au, and Cu are relatively close to each other, and only the refractive index of Al has a value that is far apart. For this reason,
When the thickness of the GdTbFe amorphous thin film is between 100 Å and 250 Å as shown in Figure 2, and a reflective film of Ag, Au, or Cu is provided, the Kerr rotation angle is very large. The Kerr rotation angle reaches its maximum value when the thickness of the crystalline thin film is around 150 Å. However, when an Al reflective film is provided, the Kerr rotation angle is small.
ここで、以上の実施例に留まらず、本発明の好
適な実施の形態として次のものが挙げられる。 In addition to the above embodiments, preferred embodiments of the present invention include the following.
(1) 第１図の構成に加え非晶質薄膜２と反射膜３
の間にSiO2、SiO、TiO2、SiN4等の断熱層を
設ける。(1) In addition to the configuration shown in Figure 1, an amorphous thin film 2 and a reflective film 3
A heat insulating layer of SiO 2 , SiO, TiO 2 , SiN 4 or the like is provided between them.
(2) 第１図の構成に加え基板１と非晶質薄膜２の
間にSiO、TiO2等の透明誘電体膜を設ける。こ
れは基板１がアクリル、ポリカーボ等の樹脂の
場合は水を含有する為ゴミやホコリに対しては
防御可能だが腐蝕に対して充分な対応が不可能
であるために設けられるものである。この場合
上記透明誘電体膜の屈折率を上記基板の屈折率
より大きく、かつ上記透明誘電体膜の膜厚を略
λ／4n（λ：入射レーザー波長、ｎ：整数）と
すれば上記基板より入射した光は上記透明誘電
体膜の内部で干渉し、それによつてカー回転角
が増大しＳ／Ｎが向上する。(2) In addition to the configuration shown in FIG. 1, a transparent dielectric film of SiO, TiO 2 or the like is provided between the substrate 1 and the amorphous thin film 2. This is provided because when the substrate 1 is made of resin such as acrylic or polycarbonate, it contains water and can protect against dirt and dust, but cannot sufficiently protect against corrosion. In this case, if the refractive index of the transparent dielectric film is greater than the refractive index of the substrate, and the thickness of the transparent dielectric film is approximately λ/4n (λ: incident laser wavelength, n: integer), then The incident light interferes inside the transparent dielectric film, thereby increasing the Kerr rotation angle and improving the S/N.
(3) 基板１に凹凸状のガイドトラツクを形成す
る。(3) Forming uneven guide tracks on the substrate 1.
(4) 非晶質薄膜２の一部を結晶化せしめガイドト
ラツクとなす。(4) Part of the amorphous thin film 2 is crystallized to form a guide track.
(5) 反射膜３に接着層を介し第２の非晶質薄膜
２、第２の基板１を設け両面使用とする。(5) The second amorphous thin film 2 and the second substrate 1 are provided on the reflective film 3 via an adhesive layer so that both sides can be used.
以上の(1)〜(5)の形態は互いに組合わせることも
可能である。 The forms (1) to (5) above can also be combined with each other.
以上説明した如く本発明によれば適切なる反射
膜を非晶質薄膜の裏面に形成することによつて、
効果的にカー回転角を増大せしめることができる
ものである。 As explained above, according to the present invention, by forming an appropriate reflective film on the back surface of the amorphous thin film,
This makes it possible to effectively increase the Kerr rotation angle.
第１図は本発明に係わる磁気光学記憶素子の一
実施例の側面断面図、第２図は特性グラフ図であ
る。
図中、１：基板、２：非晶質薄膜、３：反射
膜。
FIG. 1 is a side sectional view of one embodiment of the magneto-optical memory element according to the present invention, and FIG. 2 is a characteristic graph. In the figure, 1: substrate, 2: amorphous thin film, 3: reflective film.
Claims (1)
化容易軸を有する希土類−遷移金属非晶質薄膜を
記憶媒体とし、 該記憶媒体の裏面に入射光の波長に対する屈折
率の実数部が１以下であつて虚数部が−３乃至−
４の値を有するAg，Au，Cuのいずれかの反射膜
を設けたことを特徴とする磁気光学記憶素子。[Scope of Claims] 1. A rare earth-transition metal amorphous thin film having a film thickness of 100 Å to 250 Å and having an axis of easy magnetization perpendicular to the film surface is used as a storage medium, and the back surface of the storage medium has refraction for the wavelength of incident light. The real part of the ratio is less than or equal to 1 and the imaginary part is between -3 and -
1. A magneto-optical memory element characterized in that a reflective film of Ag, Au, or Cu having a value of 4 is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10407181A JPS586541A (en) | 1981-07-02 | 1981-07-02 | Magnetooptic storage element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10407181A JPS586541A (en) | 1981-07-02 | 1981-07-02 | Magnetooptic storage element |
Related Child Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25292590A Division JPH03228240A (en) | 1990-09-21 | 1990-09-21 | Magneto-optical recording element |
| JP24872291A Division JP2801984B2 (en) | 1991-09-27 | 1991-09-27 | Magneto-optical storage element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS586541A JPS586541A (en) | 1983-01-14 |
| JPH0263262B2 true JPH0263262B2 (en) | 1990-12-27 |
Family
ID=14370922
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10407181A Granted JPS586541A (en) | 1981-07-02 | 1981-07-02 | Magnetooptic storage element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS586541A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3382791T2 (en) * | 1982-12-15 | 1995-12-07 | Sharp Kk | Magneto-optical memory. |
| US4569881A (en) * | 1983-05-17 | 1986-02-11 | Minnesota Mining And Manufacturing Company | Multi-layer amorphous magneto optical recording medium |
| JPS6063747A (en) * | 1983-09-16 | 1985-04-12 | Sharp Corp | Magnetooptical storage element |
| JPS60209940A (en) * | 1984-03-31 | 1985-10-22 | Sony Corp | Optical recording medium |
| JPS60209942A (en) * | 1984-04-02 | 1985-10-22 | Canon Inc | Thermomagnetic recording medium |
| JPS6134748A (en) * | 1984-07-26 | 1986-02-19 | Daido Steel Co Ltd | Photoelectromagnetic recording medium and its manufacture |
| EP0598377B1 (en) * | 1992-11-17 | 1999-09-22 | Mitsubishi Chemical Corporation | Magneto-optical recording medium and optical information recording and reading-out method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5231703A (en) * | 1975-09-05 | 1977-03-10 | Kokusai Denshin Denwa Co Ltd <Kdd> | Magnetic thin film recording medium |
-
1981
- 1981-07-02 JP JP10407181A patent/JPS586541A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5231703A (en) * | 1975-09-05 | 1977-03-10 | Kokusai Denshin Denwa Co Ltd <Kdd> | Magnetic thin film recording medium |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS586541A (en) | 1983-01-14 |
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