JPH0546624B2 - - Google Patents
Info
- Publication number
- JPH0546624B2 JPH0546624B2 JP59191216A JP19121684A JPH0546624B2 JP H0546624 B2 JPH0546624 B2 JP H0546624B2 JP 59191216 A JP59191216 A JP 59191216A JP 19121684 A JP19121684 A JP 19121684A JP H0546624 B2 JPH0546624 B2 JP H0546624B2
- Authority
- JP
- Japan
- Prior art keywords
- magneto
- optical recording
- sample
- coercive force
- film
- 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
- 239000000463 material Substances 0.000 claims description 26
- 229910045601 alloy Inorganic materials 0.000 claims description 8
- 239000000956 alloy Substances 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- 229910052684 Cerium Inorganic materials 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 4
- 239000010941 cobalt Substances 0.000 claims description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 4
- 229910052735 hafnium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 230000005415 magnetization Effects 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 239000010955 niobium Substances 0.000 claims description 4
- 229910052715 tantalum Inorganic materials 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 3
- 229910052779 Neodymium Inorganic materials 0.000 claims description 3
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 239000011651 chromium Substances 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 239000010949 copper Substances 0.000 claims description 3
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 claims description 3
- 239000011733 molybdenum Substances 0.000 claims description 3
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 3
- 239000010937 tungsten Substances 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910000808 amorphous metal alloy Inorganic materials 0.000 claims description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 2
- 239000010703 silicon Substances 0.000 claims description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims 2
- 230000001678 irradiating effect Effects 0.000 claims 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 claims 1
- 239000010408 film Substances 0.000 description 39
- 239000000758 substrate Substances 0.000 description 20
- 230000000694 effects Effects 0.000 description 11
- 229910004298 SiO 2 Inorganic materials 0.000 description 10
- 239000011521 glass Substances 0.000 description 9
- 230000005291 magnetic effect Effects 0.000 description 8
- 239000010409 thin film Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- 230000005374 Kerr effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 238000004544 sputter deposition Methods 0.000 description 4
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 3
- 239000004926 polymethyl methacrylate Substances 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 229910016629 MnBi Inorganic materials 0.000 description 2
- 229910002056 binary alloy Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000005381 magnetic domain Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910000889 permalloy Inorganic materials 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 229920000515 polycarbonate Polymers 0.000 description 2
- -1 rare earth transition metal Chemical class 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002905 metal composite material Substances 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 229910002059 quaternary alloy Inorganic materials 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910002058 ternary alloy Inorganic materials 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
- G11B11/10586—Record carriers characterised by the selection of the material or by the structure or form characterised by the selection of the material
-
- 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
Description
〔技術分野〕
本発明は、膜面と垂直な方向に磁化容易軸を有
し、磁気カー効果などの磁気光学効果を利用して
読み出すことのできる磁気記録媒体に関するもの
である。
〔従来技術〕
光磁気メモリの研究は、1957年にMnBi薄膜上
に熱ペンを用いて記録を行ない、その書き込み磁
区を磁気光学効果によつて観察したのがその端諸
であるといわれている。その後のレーザーの発展
に刺激されて、MnBi系の材料を中心として精力
的な研究が行なわれてきたが、レーザ光源ならび
にその利用技術が未成熟であつたために実用化に
は至らなかつた。
しかし、1970年代における光情報処理関連技術
の進展および非晶質希土類遷移金属合金薄膜に代
表される新しい磁性薄膜材料の研究が進み、（特
許出願公告昭56−37607）GdFe，TbFe，DyFe，
GdCoなどの合金薄膜が開発されてきた。これら
の材料は、一般に次のような特徴を有している。
GdFe，GdCoなどの補償点記録用光磁気記録
媒体は、カー回転角がキユーリー点記録用光磁気
記録媒体に比較して大きく光再生特性は優れてい
るものの保磁力が小さく（数百エルステツド）
1μm程度の微小ビツトが安定に得られない。ま
た、TbFe，DyFeなどのキユーリー点記録用光
磁気記録媒体は、上述と逆に保磁力が大きく（数
キロエルステツド）1μm径程度の微小ビツトを安
定に得ることが出来るものの、カー回転角が小さ
く光再生特性があまり良くないなどの欠点を有し
ていた。またTb，Gd，Dy，Ho，etc.重希土類
は価格が高く実用に不向きである。
これらの二元合金薄膜の欠点を補うため、従来
３つの方法が試みられてきた。
(1) 三元あるいは四元化する。例えば、二元の
GdFeとTbFeの長所を生かし、欠点を補う
GdTbFe三元合金あるいはGdTbFeCo四元合金
のように多元化していく方法。（特開昭56−
126907、特開昭57−94948）
(2) 二元合金薄膜のままで、作製法の改善あるい
は新しい作製法で特性を改善する方法。（日本
応用磁気学会第27回研究会資料27−５）
(3) 多層構造化する方法。記録媒体に誘電体層を
重ねて多重反射によるカー効果の増大をはか
る。また記録層と再生層を分離して、それぞれ
に適した材料を用いる。あるいは記録媒体の裏
側に反射層を設けて、表面からの反射光だけで
なく、媒体を透過した光も反射させて利用する
などの方法である。（特開昭58−200447）
また、光磁気記録に重希土類−遷移金属を用い
反射膜のかわりにパーマロイ、Fe，Co，Niを用
いたもの（特開58−222455）も見られるが、ビツ
トが安定に存在する特徴しかなく、パーマロイ、
Fe，Co，Niが多結晶であるため、ノイズの原因
となりＳ／Ｎの劣化につながつていた。
しかしながら、これら上記の方法は、カー回転
角は大きくなるものの反射率が低下する、叉カー
回転角が多少向上してもキユーリー温度が高くな
りレーザー書き込みが難しくなるなど一長一短が
あり根本的な改善には至つていなかつた。
〔目的〕
本発明は、上記欠点であるカー回転角が小さ
い・1μmビツトが安定に得られない等の欠点を根
本的に改善し、相反する特性を向上させ高Ｓ／
Ｎ、高密度、高安定性、高速読み書きのできる光
磁気記録媒体を提供することを目的とする。
〔概要〕
本発明の光磁気記録媒体は、磁化を保持する光
磁気記録層と、抗磁力が前記光磁気記録層の五分
の一以下で且つ百エルステツド以下に選定された
低抗磁力材層とを層構造にし、前記光磁気記録層
がセリウム・ブラセオジウム・ネオジウムのうち
少なくとも一種以上の元素と鉄及び不純物からな
る合金にさらに、チタン、ジルコニウム、タンタ
ル、ハフニウム、イツトリウム、モリブデン、ホ
ウ素、ケイ素のうち少なくとも一種以上の元素を
含み、またはさらにクロム・コバルト・ニツケ
ル・銅・マンガンのうち少なくとも一種以上の元
素を含む合金からなり、且つ低抗磁力材層がチタ
ン・ジルコニウム・タンタル・ニオブ・タングス
テン・ハフニウム・イツトリウム・モリブデン・
ホウ素、硅素のうち少なくとも一種以上の元素と
コバルト及び不純物よりなり優位的に非晶質な合
金であることを特徴とする。
〔実施例〕
以下図面を用いて本発明を詳細に説明する。
本発明の基本構造を第１図ａ、第１図ｂに示
す。１１は基板、１２は光磁気記録層、１３は低
抗磁力材層、１４は非磁性層である。
尚、ここでは基板をガラス・プラスチツク等の
透明基板とし、読み書きする光学ヘツドは基板側
に対向し、基板を通して読み書きする場合を書い
たが、これは本質的なことではなく、基板に低抗
磁力材層・光磁気記録層、または低抗磁力材層・
非磁性層・光磁気記録層と形成し光学ヘツドを基
板に対し光磁気記録媒体側に対向配置して読み書
きしても何ら問題ない。さらに本発明は、前記構
造のみに限定されるものではなく、保護膜・反射
防止膜、多重干渉エンハンス膜・透明導電膜等を
設けることは何らさしつかえない。
実施例 １
(1) 第２図ａに示す構造を有する媒体で基板２３
として、よく洗浄したガラスを用い、スパツタ
法を用いてガラス基板上に厚み500Åの非晶質
NdFeTi垂直磁化膜を２２として形成し、その
上にスパツタ法を用い、２１としてCoTi非晶
質膜を1000Å形成した。上記CoTi非晶質膜の
抗磁力は約７エルステツドであり、試料No.１と
する。また比較として上記CoTi非晶質膜のか
わりにAlをスパツタ法で1000Å形成したもの
を試料No.２とする。
(2) 第２図ｂに示す構造を有する媒体で、(1)と同
様に２３はガラス基板・２２はNdFeTi膜・２
１はCoTi膜で、２４は誘電体層でSiO2を800Å
形成してある。これはNdFeTi膜ガラス基板間
に形成することによりカー回転角をエンハンス
するものである。これを試料No.３とする。また
比較として上記CoTi非晶質膜のかわりにAlを
スパツタ法で1000Å形成したものを試料No.４と
する。
(3) 第２図ｃに示す構造を有する媒体で、(2)と同
様に２３はガラス基板・２２はNdFeTi膜・２
１はCoTi膜・２４はSiO2膜である。２５は
SiO2膜で、NdFeTi膜とCoTi膜間に形成した
もので100Å厚みである。これを試料No.５とし、
比較としてCoTi膜をAl膜に置き替えたものを
試料No.６とする。
(4) 第２図ｄに示す構造を有する媒体で、２６は
PMMA基板であり1.6μm間隔・深さ700Åの案
内溝を設けたものである。また(1)と同様に２２
はNdFeTi膜・２１はCoTi膜である。これを
試料No.７とする。また比較としてCoTi非晶質
膜のかわりにAl膜を形成したものを試料No.８
とする。
(5) 第２図ｅに示す構造を有する媒体で、基板２
６として(4)と同じPMMAを用い(2)の試料No.３
と同様のSiO2／NdFeTi／CoTi構造としたも
のを試料No.９とし、比較として試料No.９の
CoTiをAlとしたものを試料No.10とする。
(6) 第２図ｆに示す構造を有する媒体で、基板２
６として、(4)と同じPMMAを用い(2)の試料No.
５と同様のSiO2／NdFeTi／SiO2／CoTi構造
としたものを試料No.11とし、比較として試料No.
11のCoTiをAlとしたものを試料No.12とする。
(7) 第２図ａの構造を有する媒体で、(1)の試料No.
１のCoTiをCoZrNbとしたものを試料No.13と
する。このCoZrNbの抗磁力は約５エルステツ
ドである。
(8) 第２図ａの構造を有する媒体で、１の試料No.
１のCoTiをCoTaとしたものを試料No.14とす
る。このCoTaの抗磁力は約６エルステツドで
ある。
(9) 第２図ａの構造を持つ媒体で、１の非晶質
NdFeTiを非晶質PrFeZr厚さ500Åとしたもの
を試料No.15とし、比較として試料No.15のCoTi
をAlとしたものを試料No.16とする。
(10) 第２図ａの構造を持つ媒体で(1)の非晶質
NdFeTiを厚み500ÅのCeFeTaCrとしたもの
を試料No.17とし、比較のため試料No.17のCoTi
をAlとしたものを試料No.18とする。
(11) 第２図ａの構造を有する媒体で、(1)の試料No.
１のNdFeTiをNdPrFeとしたものを試料No.19
とし、比較のため試料19のCoTiをAlとしたも
のを試料２０とする。
(12) 第２図ａの構造を有する媒体で、(1)の試料No.
１のNdFeTiをNdFeHfCoとしたものを試料No.
21とし、比較のため試料No.21のCoTeをAlとし
たものを試料No.22とする。
(13) 第２図ｅの構造を有する媒体で、(5)の試料No.
９のNdFeTiをTbFeとしたものを試料No.23と
し、比較のため試料No.23のCoTiをAlとしたも
のを試料No.24とする。
以上23種類のサンプルについてカー効果を測定
した。カー効果の測定は試料に10キロエルステツ
ドの磁場をかけ、残留磁化状態としHe−Neガス
レーザー（波長632.8ナノメートル）で測定した。
測定の結果を表１に示す。
(1)〜(6)の試料No.〜試料12においてすべての構造
で非晶質CoTiを用いたものはAlに比してカー回
転角はほぼ、２倍に増加している。また(7)，(8)の
試料１３及び試料１４においてCoTi以外のCo系
非晶質薄膜を用いた場合においても、試料２の
Alに対してやはり２倍程度の増加があつた。
(9)〜(12)において記録層としてPrFeZr，
CeFeTaCr，NdPrFe，NdFeHfCoとしたものに
おいてもやはりカー回転角は大きくなつた。
(13)は従来より光磁気記録媒体として用いられて
いるTbFeを記録層としカー回転角を測定したが
この場合でも約1.5倍に増加した。
尚、光磁気記録媒体にCr，Ni，Cu，Mnを添
加したものは、試料２１のCo添加と同一の効果
で耐候性に優れ、膜面に垂直に磁気容易軸を有す
る光磁気記録媒体であつた。さらに、ここでは、
Co系アモルフアス低抗磁力材層の具体例として、
CoにTi，Zr，Ta，Nbを少なくとも一種以上添
加した材料で本発明の効果を説明したが、これに
限定されず、CoにＷ，Hf，Ｙ，Mo，Ｂ，Siを添
加した材料でも効果は全く同じである。
実施例 ２
低抗磁力材層の抗磁力とカー回転角の関係を調
べた。結果を第３図に示す。第３図において横軸
は抗磁力、縦軸はカー回転角である。用いた試料
はすべて第２図ａの構造を有するもので、ａはガ
ラス／NdFeTi／CoTi，ｂはガラス／NdFeTi／
CoZrNb，ｃはガラス／TbFe／CoTiである。
ａ，ｂ，ｃの３種数すべて低抗磁力層の抗磁力が
小さくなるに従つてカー回転角が増加する。しか
し抗磁力が約100エルステツド程度になると、Al
の反射層を設けたものと同等となる。（図中ｄ，
ｅ）さらに抗磁力が大きくなつた場合にはむしろ
Alに比してカー回転角は小さくなる。これは、
反射率がAlに比してCo系合金が小さいためであ
る。
[Technical Field] The present invention relates to a magnetic recording medium that has an axis of easy magnetization in a direction perpendicular to the film surface and can be read using magneto-optical effects such as the magnetic Kerr effect. [Prior art] Research on magneto-optical memory is said to have started in 1957, when recording was performed using a hot pen on a MnBi thin film, and the written magnetic domain was observed using the magneto-optic effect. . Stimulated by the subsequent development of lasers, intensive research has been carried out mainly on MnBi-based materials, but practical application was not achieved due to the immaturity of laser light sources and the technology for their use. However, in the 1970s, advances in optical information processing related technology and research into new magnetic thin film materials such as amorphous rare earth transition metal alloy thin films progressed (Patent Application Publication 1982-37607).GdFe, TbFe, DyFe,
Alloy thin films such as GdCo have been developed. These materials generally have the following characteristics. Magneto-optical recording media for compensation point recording such as GdFe and GdCo have a larger Kerr rotation angle than magneto-optical recording media for Curie point recording, and have excellent optical reproduction characteristics, but have a small coercive force (several hundred oersteds).
It is not possible to stably obtain minute bits of about 1 μm. In addition, magneto-optical recording media for Curie point recording such as TbFe and DyFe have a large coercive force (several kiloersteds) and can stably obtain minute bits with a diameter of about 1 μm, contrary to the above, but the Kerr rotation angle is small and the optical It had drawbacks such as poor reproduction characteristics. In addition, heavy rare earths such as Tb, Gd, Dy, Ho, etc. are expensive and unsuitable for practical use. In order to compensate for the drawbacks of these binary alloy thin films, three methods have been attempted in the past. (1) To become ternary or quaternary. For example, the binary
Take advantage of the strengths of GdFe and TbFe and compensate for their weaknesses
A method of diversification such as GdTbFe ternary alloy or GdTbFeCo quaternary alloy. (Unexamined Japanese Patent Publication 1983-
126907, JP-A-57-94948) (2) A method of improving the properties of a binary alloy thin film by improving the manufacturing method or using a new manufacturing method. (Material 27-5 of the 27th Research Meeting of the Japanese Society of Applied Magnetics) (3) Method of creating a multilayer structure. A dielectric layer is layered on the recording medium to increase the Kerr effect due to multiple reflections. Furthermore, the recording layer and the reproducing layer are separated, and materials suitable for each are used. Alternatively, a reflective layer may be provided on the back side of the recording medium to reflect and utilize not only the light reflected from the surface but also the light that has passed through the medium. (Japanese Patent Application Laid-open No. 58-200447) There are also systems in which heavy rare earth-transition metals are used for magneto-optical recording and permalloy, Fe, Co, and Ni are used instead of the reflective film (Japanese Patent Application Laid-Open No. 58-222455). Permalloy has only the characteristic of stably existing.
Since Fe, Co, and Ni are polycrystalline, they cause noise and lead to deterioration of S/N. However, these methods have both advantages and disadvantages, such as increasing the Kerr rotation angle but decreasing the reflectance, and even if the Kerr rotation angle is slightly improved, the Curie temperature increases, making laser writing difficult. was not yet reached. [Purpose] The present invention fundamentally improves the above-mentioned drawbacks such as a small Kerr rotation angle and inability to stably obtain 1 μm bits, improves contradictory characteristics, and achieves high S/
The object of the present invention is to provide a magneto-optical recording medium that is high in density, highly stable, and capable of high-speed reading and writing. [Summary] The magneto-optical recording medium of the present invention comprises a magneto-optical recording layer that retains magnetization, and a low coercive force material layer whose coercive force is selected to be one-fifth or less of the magneto-optical recording layer and 100 oersted or less. The magneto-optical recording layer is made of an alloy consisting of at least one element selected from cerium, braseodymium, and neodymium, iron, and impurities; It is made of an alloy containing at least one of the following elements, or further contains at least one element of chromium, cobalt, nickel, copper, and manganese, and the low coercive force material layer is made of titanium, zirconium, tantalum, niobium, tungsten, hafnium yztrium molybdenum
It is characterized by being a predominantly amorphous alloy consisting of at least one element among boron and silicon, cobalt, and impurities. [Example] The present invention will be explained in detail below using the drawings. The basic structure of the present invention is shown in FIGS. 1a and 1b. 11 is a substrate, 12 is a magneto-optical recording layer, 13 is a low coercive force material layer, and 14 is a nonmagnetic layer. In this case, the substrate is a transparent substrate such as glass or plastic, and the optical head for reading and writing faces the substrate side, and reading and writing is done through the substrate. However, this is not essential, and the substrate has a low coercive force. material layer, magneto-optical recording layer, or low coercive force material layer,
There is no problem even if a non-magnetic layer and a magneto-optical recording layer are formed and the optical head is placed facing the magneto-optical recording medium side with respect to the substrate for reading and writing. Furthermore, the present invention is not limited to the above-mentioned structure, and there is no problem in providing a protective film, an antireflection film, a multiple interference enhancement film, a transparent conductive film, etc. Example 1 (1) The substrate 23 is made of a medium having the structure shown in FIG. 2a.
Using well-cleaned glass, a 500 Å thick amorphous film was deposited on the glass substrate using the sputtering method.
An NdFeTi perpendicularly magnetized film 22 was formed, and a CoTi amorphous film 21 with a thickness of 1000 Å was formed thereon using a sputtering method. The CoTi amorphous film has a coercive force of about 7 oersteds, and is designated as sample No. 1. For comparison, sample No. 2 is prepared by forming Al with a thickness of 1000 Å by sputtering instead of the above CoTi amorphous film. (2) A medium having the structure shown in Fig. 2b, where 23 is a glass substrate, 22 is an NdFeTi film, and 2
1 is a CoTi film, 24 is a dielectric layer made of SiO 2 with a thickness of 800 Å
It has been formed. This enhances the Kerr rotation angle by forming an NdFeTi film between the glass substrates. This is designated as sample No. 3. For comparison, sample No. 4 was prepared by forming Al with a thickness of 1000 Å by sputtering instead of the CoTi amorphous film. (3) A medium having the structure shown in Figure 2c, where 23 is a glass substrate, 22 is an NdFeTi film, and 2
1 is a CoTi film and 24 is a SiO 2 film. 25 is
It is a SiO 2 film formed between the NdFeTi film and the CoTi film, and is 100 Å thick. This is sample No. 5,
For comparison, sample No. 6 is prepared by replacing the CoTi film with an Al film. (4) A medium having the structure shown in Figure 2d, where 26 is
It is a PMMA substrate with guide grooves 1.6 μm apart and 700 Å deep. Also, similar to (1), 22
21 is a NdFeTi film and 21 is a CoTi film. This is designated as sample No. 7. For comparison, sample No. 8 was prepared with an Al film instead of the CoTi amorphous film.
shall be. (5) The substrate 2 is a medium having the structure shown in Figure 2e.
Sample No. 3 of (2) was used as sample No. 6 using the same PMMA as in (4).
Sample No.9 has the same SiO 2 /NdFeTi/CoTi structure, and for comparison, sample No.9 has the same SiO 2 /NdFeTi/CoTi structure.
Specimen No. 10 is a sample in which CoTi is replaced by Al. (6) The substrate 2 is a medium having the structure shown in Fig. 2 f.
As sample No. 6, use the same PMMA as in (4) and sample No. 6 in (2).
Sample No. 11 has the same SiO 2 /NdFeTi/SiO 2 /CoTi structure as in No. 5, and Sample No. 11 has the same SiO 2 /NdFeTi/SiO 2 /CoTi structure.
Sample No. 12 is a sample in which CoTi of No. 11 is replaced with Al. (7) A medium with the structure shown in Figure 2a, sample No. (1).
Sample No. 13 is a sample in which CoTi of No. 1 is replaced with CoZrNb. The coercive force of this CoZrNb is about 5 Oersteds. (8) Sample No. 1 with a medium having the structure shown in Figure 2 a.
Sample No. 14 is obtained by replacing CoTi of No. 1 with CoTa. The coercive force of this CoTa is about 6 oersted. (9) A medium with the structure shown in Figure 2 a, which is an amorphous material of 1.
Sample No. 15 is made of NdFeTi with amorphous PrFeZr thickness of 500 Å, and for comparison, the CoTi of sample No. 15 is
Sample No. 16 is the one in which Al is used. (10) In a medium with the structure shown in Figure 2 a, the amorphous state of (1)
Sample No. 17 is NdFeTi made of CeFeTaCr with a thickness of 500 Å, and for comparison, the CoTi of sample No. 17 is
Sample No. 18 is the one in which Al is used. (11) A medium with the structure shown in Figure 2a, sample No. (1).
Sample No. 19 is the one in which NdFeTi of No. 1 is replaced with NdPrFe.
For comparison, Sample 20 is Sample 19 in which CoTi is replaced with Al. (12) A medium with the structure shown in Figure 2a, sample No. (1).
Sample No. 1 was prepared by replacing NdFeTi with NdFeHfCo.
21, and for comparison, Sample No. 22 is the one in which CoTe of Sample No. 21 is replaced with Al. (13) Sample No. (5) with a medium having the structure shown in Figure 2 e.
Sample No. 23 is obtained by replacing the NdFeTi of No. 9 with TbFe, and for comparison, sample No. 24 is obtained by replacing CoTi of Sample No. 23 with Al. The Kerr effect was measured for the above 23 types of samples. The Kerr effect was measured using a He-Ne gas laser (wavelength: 632.8 nanometers) by applying a magnetic field of 10 kiloersteds to the sample and setting it in a remanent magnetized state.
The measurement results are shown in Table 1. In Sample No. to Sample 12 of (1) to (6), the Kerr rotation angle of all structures using amorphous CoTi is approximately twice as large as that of Al. Furthermore, even when Co-based amorphous thin films other than CoTi are used in Samples 13 and 14 of (7) and (8), Sample 2
As expected, the increase was about twice that of Al. In (9) to (12), PrFeZr was used as the recording layer.
The Kerr rotation angle also increased for CeFeTaCr, NdPrFe, and NdFeHfCo. (13) measured the Kerr rotation angle using TbFe, which has been conventionally used as a magneto-optical recording medium, as a recording layer, but even in this case it increased by about 1.5 times. In addition, magneto-optical recording media to which Cr, Ni, Cu, and Mn are added have the same effect as Co addition in sample 21, have excellent weather resistance, and have a magnetic easy axis perpendicular to the film surface. It was hot. Furthermore, here:
As a specific example of a Co-based amorphous low coercive force material layer,
Although the effects of the present invention have been explained using a material in which at least one of Ti, Zr, Ta, and Nb is added to Co, the present invention is not limited to this, and materials in which W, Hf, Y, Mo, B, and Si are added to Co can also be used. The effect is exactly the same. Example 2 The relationship between the coercive force of the low coercive force material layer and the Kerr rotation angle was investigated. The results are shown in Figure 3. In FIG. 3, the horizontal axis is the coercive force, and the vertical axis is the Kerr rotation angle. All the samples used had the structure shown in Figure 2a, where a is glass/NdFeTi/CoTi and b is glass/NdFeTi/
CoZrNb,c is glass/TbFe/CoTi.
The Kerr rotation angle increases as the coercive force of the low coercive force layer decreases for all three species a, b, and c. However, when the coercive force becomes about 100 oersted, Al
This is equivalent to having a reflective layer. (d in the figure,
e) If the coercive force becomes even larger, rather
The Kerr rotation angle is smaller than that of Al. this is,
This is because the reflectance of the Co-based alloy is lower than that of Al.
【表】【table】
【表】
実施例 ３
光磁気記録再生可能な光学ヘツドを用い、第４
図ａに示す媒体構造で周波数特性を調べた。レー
ザー波長は780nmの半導体レーザーを用いた。デ
イスク回転数は1800rpm、半径５cmに固定とし、
書き込み周波数を可変させた。読み書きは基板側
から行つた。基板はグループ付ポリカーボネイト
４１とし、第２表に記したような薄膜を形成し、
３層構造とした。
第１層はAlN４２で800A、第２層は光磁気記
録層４３で1000A、第３層は従来例としてAl反射
膜または本発明によるアモルフアスCo系低抗磁
力膜４４でここではCo30Ti20とし、500Aの膜厚
とした。形成手段はDCマグネトロンスパツタ法
とした。それぞれの光磁気記録媒体における書き
込み周波数に対するＣ／Ｎを示したものが第４図
ｂである。従来の様な反射膜として非磁性Alを
用いた場合と較べ本発明によるアモルフアスCo
系低抗磁力層を設けたことによりＣ／Ｎが上昇し
た。さらに、本発明によるFe中にCe，Pr，Ndを
少なくとも一種以上含んだ光磁気記録媒体におい
ては、さらにその効果は大きく、書き込み周波数
特性が飛躍的に向上する。以上の実施例中で、光
磁気記録層、低抗磁力材層、反射膜の他にSiO2、
AlN等の透明な誘電体の膜を用いたが、このよ
うなセラミツク膜以外の有機物、有機物金属複合
膜、有機物セラミツク複合膜を用いても本発明の
効果は同様に得られた。[Table] Example 3 Using an optical head capable of magneto-optical recording and reproduction, the fourth
The frequency characteristics were investigated using the medium structure shown in Figure a. A semiconductor laser with a laser wavelength of 780 nm was used. The disk rotation speed is fixed at 1800 rpm and a radius of 5 cm.
The writing frequency was varied. Reading and writing were performed from the board side. The substrate was polycarbonate 41 with groups, and a thin film as shown in Table 2 was formed.
It has a three-layer structure. The first layer is AlN42 with a current of 800A, the second layer is a magneto-optical recording layer 43 with a current of 1000A, and the third layer is a conventional Al reflective film or an amorphous Co-based low coercive force film 44 according to the present invention, which is Co 30 Ti 20 here. , the film thickness was 500A. The forming means was the DC magnetron sputtering method. FIG. 4b shows the C/N with respect to the writing frequency in each magneto-optical recording medium. Compared to the conventional case where non-magnetic Al is used as a reflective film, the amorphous Co according to the present invention
The C/N was increased by providing the low coercive force layer. Furthermore, in the magneto-optical recording medium containing at least one of Ce, Pr, and Nd in Fe according to the present invention, the effect is even greater, and the writing frequency characteristics are dramatically improved. In the above embodiments, in addition to the magneto-optical recording layer, the low coercive force material layer, and the reflective film, SiO 2 ,
Although a transparent dielectric film such as AlN was used, the same effect of the present invention could be obtained by using an organic material, an organic-metal composite film, or an organic-ceramic composite film other than such a ceramic film.
【表】【table】
以上の実施例に示された様に本発明による構造
を有する光磁気記録媒体は、カー回転角がほぼ２
倍に増加し、Ｃ／Ｎ比も改善される。
さらに、記録磁区が安定するために高記録密度
においてもＣ／Ｎ比の劣化が小さく、より高密度
記録に適した媒体である。
また、従来のTbFe，GdCo，TbFeCo，
TbGdFe等の重希土類を含む媒体に比してNd，
Pr，Ceの軽希土類を含むものは材料費が安くな
り、本発明による光磁気記録媒体は、軽希土類を
含む媒体に対しての方がその効果が大きいという
特徴をもつている。
記録層は、非晶質であるため記録層上にCo系
非晶質を成長させる、あるいは逆にCo系非晶質
層上に非晶質の光磁気記録層を成長させることは
非常に容易であり、且つ、Co系非晶質は非常に
化学的に安定であるため信頼性も向上し、耐候性
の向上になる。
As shown in the above embodiments, the magneto-optical recording medium having the structure according to the present invention has a Kerr rotation angle of approximately 2.
The C/N ratio is also improved. Furthermore, since the recording magnetic domain is stable, there is little deterioration in the C/N ratio even at high recording densities, making the medium more suitable for high-density recording. In addition, conventional TbFe, GdCo, TbFeCo,
Compared to media containing heavy rare earths such as TbGdFe, Nd,
Materials containing light rare earth elements such as Pr and Ce are cheaper in material cost, and the magneto-optical recording medium according to the present invention is characterized in that the effect is greater for media containing light rare earth elements. Since the recording layer is amorphous, it is very easy to grow a Co-based amorphous layer on the recording layer, or conversely, to grow an amorphous magneto-optical recording layer on a Co-based amorphous layer. Moreover, since the Co-based amorphous material is extremely chemically stable, reliability is improved and weather resistance is improved.
第１図ａ，ｂは、本発明による光磁気記録媒体
の基本的層構造を示す図である。第２図ａ〜ｆ
は、本発明による光磁気記録媒体の具体的実施例
の構造を示す図である。第３図は本発明の低抗磁
力材層の効果を示す図で、低抗磁力材層の抗磁力
に対して、光磁気記録層のカー回転角をプロツト
したものである。第４図ｂは、本発明の光磁気記
録媒体の書き込み周波数特性を示す図で、光磁気
記録媒体の構造を第４図ａとし、光磁気記録層
を、各種変えた場合の本発明の効果を示す実施例
である。
１１……基板、１２……光磁気記録層、１３…
…低抗磁力材層、１４……非磁性層、２１……低
抗磁力材層もしくは反射膜、２２……光磁気記録
層、２３……基板、２４……誘電体層、２５……
誘電体層、２６……基板、４１……ポリカーボネ
ート基板、４２……AlN層、４３……光磁気記
録層、４４……低抗磁力材層もしくは反射膜。
FIGS. 1a and 1b are diagrams showing the basic layer structure of a magneto-optical recording medium according to the present invention. Figure 2 a-f
1 is a diagram showing the structure of a specific example of a magneto-optical recording medium according to the present invention. FIG. 3 is a diagram showing the effect of the low coercive force material layer of the present invention, in which the Kerr rotation angle of the magneto-optical recording layer is plotted against the coercive force of the low coercive force material layer. FIG. 4b is a diagram showing the writing frequency characteristics of the magneto-optical recording medium of the present invention. The structure of the magneto-optical recording medium is shown in FIG. 4a, and the effects of the present invention when the magneto-optical recording layer is variously changed. This is an example showing the following. 11...Substrate, 12...Magneto-optical recording layer, 13...
...Low coercive force material layer, 14...Nonmagnetic layer, 21...Low coercive force material layer or reflective film, 22...Magneto-optical recording layer, 23...Substrate, 24...Dielectric layer, 25...
Dielectric layer, 26...Substrate, 41...Polycarbonate substrate, 42...AlN layer, 43...Magneto-optical recording layer, 44...Low coercive force material layer or reflective film.
Claims (1)
かの二値をとる光磁気記録層に光を照射し、記録
再生を行う光磁気記録媒体において、磁化を保持
する前記光磁気記録層と、抗磁力が前記光磁気記
録層の五分の一以下で且つ百エルステツド以下に
選定された低抗磁力材層とを層構造にし、前記光
磁気記録層がセリウム、プラセオジム、ネオジム
のうち少なくとも一種以上の元素と、鉄からなる
合金、あるいは該合金にさらに、チタン、ジルコ
ニウム、タンタル、ハフニウム、ニオブ、タング
ステン、イツトリウム、モリブデンのうち少なく
とも一種以上の元素を含み、またはさらにクロ
ム、コバルト、ニツケル、銅、マンガンのうち少
なくとも一種以上の元素を含む合金から成り、且
つ前記低抗磁力材層がチタン、ジルコニウム、タ
ンタル、ニオブ、タングステン、ハフニウム、イ
ツトリウム、モリブデン、ホウ素、ケイ素のうち
少なくとも一種以上の元素とコバルトよりなり優
位的に非晶質な合金であることを特徴とする光磁
気記録媒体。1. In a magneto-optical recording medium in which recording and reproduction is performed by irradiating light onto a magneto-optical recording layer whose magnetization direction is perpendicular to the film surface and has a binary value of upward or downward, the magneto-optical recording layer retains magnetization. , the magneto-optical recording layer has a layered structure including a low coercive force material layer whose coercive force is selected to be one-fifth or less of the magneto-optical recording layer and 100 Oersted or less, and the magneto-optical recording layer is made of at least one of cerium, praseodymium, and neodymium. An alloy consisting of the above elements and iron, or the alloy further contains at least one element selected from titanium, zirconium, tantalum, hafnium, niobium, tungsten, yttrium, and molybdenum, or further contains chromium, cobalt, nickel, and copper. or manganese, and the low coercive force material layer is made of an alloy containing at least one element among titanium, zirconium, tantalum, niobium, tungsten, hafnium, yttrium, molybdenum, boron, and silicon. A magneto-optical recording medium characterized by being a predominantly amorphous alloy consisting of cobalt.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19121684A JPS6187250A (en) | 1984-09-12 | 1984-09-12 | Photomagnetic recording medium |
| US07/193,020 US5100741A (en) | 1984-09-12 | 1988-05-12 | Magneto-optic recording systems |
| US08/231,866 US5529854A (en) | 1984-09-12 | 1994-04-25 | Magneto-optic recording systems |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19121684A JPS6187250A (en) | 1984-09-12 | 1984-09-12 | Photomagnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6187250A JPS6187250A (en) | 1986-05-02 |
| JPH0546624B2 true JPH0546624B2 (en) | 1993-07-14 |
Family
ID=16270837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19121684A Granted JPS6187250A (en) | 1984-09-12 | 1984-09-12 | Photomagnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6187250A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59191213A (en) * | 1983-04-15 | 1984-10-30 | 昭和電線電纜株式会社 | Method of producing compound composite superconductive conductor |
-
1984
- 1984-09-12 JP JP19121684A patent/JPS6187250A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59191213A (en) * | 1983-04-15 | 1984-10-30 | 昭和電線電纜株式会社 | Method of producing compound composite superconductive conductor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6187250A (en) | 1986-05-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |