JPH0322211A - Magnetic recording medium - Google Patents
Magnetic recording mediumInfo
- Publication number
- JPH0322211A JPH0322211A JP15589789A JP15589789A JPH0322211A JP H0322211 A JPH0322211 A JP H0322211A JP 15589789 A JP15589789 A JP 15589789A JP 15589789 A JP15589789 A JP 15589789A JP H0322211 A JPH0322211 A JP H0322211A
- Authority
- JP
- Japan
- Prior art keywords
- recording medium
- fine particles
- magnetic
- recording
- magnetic recording
- 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.)
- Granted
Links
- 230000005291 magnetic effect Effects 0.000 title claims description 25
- 239000010419 fine particle Substances 0.000 claims abstract description 20
- 239000000758 substrate Substances 0.000 claims abstract description 10
- 239000003302 ferromagnetic material Substances 0.000 claims abstract description 8
- 230000005381 magnetic domain Effects 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 7
- 229910000531 Co alloy Inorganic materials 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 229910000640 Fe alloy Inorganic materials 0.000 abstract description 2
- 229910000990 Ni alloy Inorganic materials 0.000 abstract description 2
- 238000004380 ashing Methods 0.000 abstract description 2
- 238000010894 electron beam technology Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 abstract description 2
- 239000002245 particle Substances 0.000 abstract description 2
- 238000004544 sputter deposition Methods 0.000 abstract description 2
- 239000010408 film Substances 0.000 abstract 2
- 239000010409 thin film Substances 0.000 abstract 1
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000001723 curing Methods 0.000 description 2
- 230000005347 demagnetization Effects 0.000 description 2
- 230000005294 ferromagnetic effect Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 229910020630 Co Ni Inorganic materials 0.000 description 1
- 229910020637 Co-Cu Inorganic materials 0.000 description 1
- 229910002440 Co–Ni Inorganic materials 0.000 description 1
- 229910002551 Fe-Mn Inorganic materials 0.000 description 1
- 229910002546 FeCo Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910018651 Mn—Ni Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000000609 electron-beam lithography Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229910001291 heusler alloy Inorganic materials 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- NQNBVCBUOCNRFZ-UHFFFAOYSA-N nickel ferrite Chemical compound [Ni]=O.O=[Fe]O[Fe]=O NQNBVCBUOCNRFZ-UHFFFAOYSA-N 0.000 description 1
- 238000011017 operating method Methods 0.000 description 1
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 238000000016 photochemical curing Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 238000005546 reactive sputtering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Landscapes
- Magnetic Record Carriers (AREA)
- Manufacturing Of Magnetic Record Carriers (AREA)
Abstract
Description
【発明の詳細な説明】
(産業上の利用分野)
この発明は、磁気記録媒体に関するものである.さらに
詳しくは、この発明は、書き換え可能な高記録密度の新
しい磁気記録媒体に関するものである.
(従来の技術とその課題)
従来より様々な形式と構造の記録媒体が知られており、
すでにかなりの高記録密度と書き換え可能性を有する記
録媒体が実用化され、また開発中でもある,
たとえばすでに実用化されているものとしては、記録密
度が約105〜106bit/一で書き換え可能な塗布
型の磁気ディスクや磁気テープがある.またさらに記録
密度を向上させたものとしては、1 07bit/一の
光ディスクがある.今後実用化されるものと予測される
光磁気ディスクは、この光ディスクの場合の書き換えの
不可能な欠点を克服し、1 07bit/一のオーダー
の記録密度を有し、しかも書き換え可能なものとして期
待されている.開発中のものには垂直磁気記録もある.
この場合にも1 0 7bit/cdオーダーの記録密
度を有し、しかも書き換え可能なものが開発の目標とさ
れている.
しかしながら、これまでに知られている、また開発中の
ものも含めて公知の記録媒体は、いずれもその記録密度
が107bit/一程度にとどまり、これ以上の超高記
録密度を有し、しかも書き換えが可能である新しい記録
媒体の実用化については、その方式や構造の着想すら乏
しいのが実情である.この発明は、以上の通りの事情に
鑑みてなされたものであり、これまでの記録媒体の限界
と欠点を克服し、飛躍的に記録密度を高めることができ
、しかも書き換え可能な新しい記録媒体を提供すること
を目的としている.さらにこの発明は、雑音が少く、ま
た、減磁作用が小さくて、記録読出時の信号強度の大き
い新しい超高記録密度の書き換え可能な記録媒体を提供
することを目的としている。[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a magnetic recording medium. More specifically, the present invention relates to a new rewritable high-density magnetic recording medium. (Conventional technology and its problems) Recording media of various formats and structures have been known for a long time.
Recording media with considerably high recording densities and rewritability have already been put into practical use, and are under development. For example, one example of a recording medium that has already been put into practical use is a coated type that is rewritable with a recording density of approximately 105 to 106 bits/1. There are magnetic disks and magnetic tapes. Furthermore, there is an optical disc with a recording density of 107 bits per unit. Magneto-optical disks, which are expected to be put into practical use in the future, are expected to overcome the disadvantage of optical disks in that they cannot be rewritten, have a recording density on the order of 107 bits/1, and are also rewritable. It has been done. Perpendicular magnetic recording is also under development.
In this case as well, the goal of development is to have a recording density on the order of 107 bits/cd and to be rewritable. However, all known recording media, including those known to date and those under development, have a recording density of only about 107 bits/1, and have ultra-high recording densities even higher than this, and are rewritable. The reality is that there are few ideas for the method or structure of a new recording medium that can be put into practical use. This invention was made in view of the above-mentioned circumstances, and aims to overcome the limitations and drawbacks of conventional recording media, dramatically increase recording density, and create a new rewritable recording medium. The purpose is to provide. A further object of the present invention is to provide a new ultra-high recording density rewritable recording medium with low noise, low demagnetization effect, and high signal strength during recording and reading.
(課題を解決するための手段)
この発明は、上記の課題を解決するものとして、徴粒子
1個に1ビットを記録する方式を提供し、かつその方式
を実現するものとして、強磁性物質からなる形状が一定
の単磁区微粒子を非磁性基板上に対称配列してなること
を特徴とする磁気記録媒体を提供する。(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method of recording one bit in one characteristic particle, and as a means of realizing the method, it is possible to use ferromagnetic materials. The present invention provides a magnetic recording medium characterized in that single-domain fine particles having a constant shape are arranged symmetrically on a non-magnetic substrate.
添附した図面に沿ってこの発明の磁気記録媒体について
詳しく説明すると、この磁気記録媒体は、概略的には第
1図に示したような楕遣を有している。The magnetic recording medium of the present invention will be described in detail with reference to the accompanying drawings. This magnetic recording medium has an ellipse as shown schematically in FIG.
すなわち、この第1図がち明らかなように、非磁性基板
(1)の上に、単磁区微粒子(2)を所定の間隔を介し
て対称的に整合をとって配列している.この単磁区微粒
子(2)は各々記録媒体の要素となり、図中の矢印で示
したように記録系を楕成していく.
この単磁区微粒子(2〉は、強磁性物質からなり、その
種類には様々なものが採用できる。たとえば、金属また
は合金としては、Fe,FeCo,Fe−Nl,Fe−
Cu,Fe−Pt、Fe−MnなどのFe合金、CO、
Co−Ni、Co−CuなどのCO合金、Ni,Ni−
Cu、Mn−NiなどのNi合金が示される。That is, as is clear from FIG. 1, single-domain fine particles (2) are arranged symmetrically and aligned at predetermined intervals on a non-magnetic substrate (1). Each of these single-domain fine particles (2) becomes an element of a recording medium, forming an elliptical recording system as shown by the arrows in the figure. The single magnetic domain fine particles (2) are made of a ferromagnetic substance, and various types can be adopted.For example, metals or alloys include Fe, FeCo, Fe-Nl, Fe-
Fe alloys such as Cu, Fe-Pt, Fe-Mn, CO,
CO alloys such as Co-Ni and Co-Cu, Ni, Ni-
Ni alloys such as Cu and Mn-Ni are shown.
金属間化合物としてF e 3A j 、ホイスラー合
金などを使用することもできる。また、酸化物でもよく
、マンガンフエライト、ニッケルフエライト、バリウム
フェライト、コバルトフエライトなどのフエライト類や
、マグネタイト(Fe304)、マグヘマイト(γ−F
e 2 0 3)などを例示することができる。F e 3A j , Heusler alloy, etc. can also be used as the intermetallic compound. In addition, oxides may be used, such as ferrites such as manganese ferrite, nickel ferrite, barium ferrite, and cobalt ferrite, magnetite (Fe304), and maghemite (γ-F
e 2 0 3), etc.
これらの強磁性物質からなる単磁区微粒子(2)は、隣
接するものと、その大きさおよび形状を対称的なものと
し、この大きさ、および相互の間隔を、磁気記録媒体の
作動方式に対応させて整合させ、所要の大きさと位置で
対称配列する.この単磁区微粒子(2)の形状は、保持
力を大きくするためにも、第1図に例示したように細長
くすることが好適であるが、その形状は必ずしも長方形
である必要はない.複数のものが均等性を持つように、
たとえば楕円形であってもよい.一般的には、細長い形
状として、その長さ(j)は、巾(W)の2〜10倍と
し、高さ(h)を巾(W)と略均等とすることが好まし
い.また、単磁区漱粒子(2)相互の間隔(s )(s
2)は、1
巾(W)と均等としてもよい.
表1は、この単磁区微粒子(2)の大きさ(WXjXh
)と、相互の間隔(S1 ) (S2 )の目安とし
て、巾(W)の好ましい範囲を例示したものである.
もちろん、この表1の数字は限定的なものでなく、単磁
区を形成するための目安となるものである.
このような単磁区微粒子(2)は、非磁性基板(1)上
に規則的に対称配列するが、この場合、その配列は、第
1図に示したような矩形の格子状のみならず、円盤状の
非磁性基板に沿った多数の同心円状あるいは円形うす巻
き状であってもよい.もちろんこれに限定されるもので
はなく、一定の対称性をもった整然とした配列態様であ
れば何であってもよい.その配列の形状は、単磁区微粒
子(2〉の成長によって、あるいは、エッチング法など
との組合わせによって適宜に行うことができる.
より好適には、微小ビーム構図プロセスによってこれら
の単磁区微粒子(2)を形成・配列することができる.
く表 1〉
このビーム描画プロセスを例示したものが第2図である
.
(a)
非磁性基板(1)の上に、レジスト
膜(3)を塗布する.非磁性基板(1)としては、ガラ
ス、樹脂、その他任意のものであってもよい.その形状
も、円盤状のものから、他の適宜なものとすることがで
きる.
レジスト膜(3)は、熟硬化性、光硬
化性、その他のタイプのものとすることができる。These single-domain fine particles (2) made of ferromagnetic material are symmetrical in size and shape with those of the adjacent ones, and the size and mutual spacing correspond to the operating method of the magnetic recording medium. Align them and arrange them symmetrically with the required size and position. In order to increase the coercive force, the shape of the single magnetic domain fine particles (2) is preferably elongated as illustrated in FIG. 1, but the shape does not necessarily have to be rectangular. Just as multiple things have equality,
For example, it may be oval. Generally, it is preferable that the length (j) is 2 to 10 times the width (W) and the height (h) is approximately equal to the width (W) of the elongated shape. In addition, the distance between the single magnetic domain grains (2) (s) (s
2) may be equal to 1 width (W). Table 1 shows the size (WXjXh
), and the preferred range of the width (W) as a guideline for the mutual spacing (S1) (S2). Of course, the numbers in Table 1 are not limiting, but serve as a guideline for forming a single magnetic domain. Such single-domain fine particles (2) are regularly and symmetrically arranged on the non-magnetic substrate (1), but in this case, the arrangement is not only in a rectangular lattice shape as shown in FIG. It may also be in the form of many concentric circles or a thin circular spiral along a disc-shaped non-magnetic substrate. Of course, the arrangement is not limited to this, and any orderly arrangement with a certain degree of symmetry may be used. The shape of the array can be appropriately formed by growing single magnetic domain fine particles (2) or by combining with an etching method. More preferably, these single magnetic domain fine particles (2) ) can be formed and arranged. Table 1 Figure 2 shows an example of this beam writing process. (a) Coating a resist film (3) on a non-magnetic substrate (1) .The nonmagnetic substrate (1) may be made of glass, resin, or any other material.The shape thereof may be a disc or any other appropriate shape.Resist film (3) The curing agent may be of a ripe curing type, a photo curing type, or other types.
このレジスト膜(3)を電子ビーム等
のビームによって所定のパターンに描画し、現象して、
所定の部位のレジストを除去する.
(C) 次いで、スパッタリング、真空蒸着等の気相
成脱法によって強磁性物質の薄11!(4)を形成する
。This resist film (3) is drawn in a predetermined pattern with a beam such as an electron beam, and then developed.
Remove the resist from the specified area. (C) Next, a thin layer of ferromagnetic material 11! is formed using a vapor phase deposition method such as sputtering or vacuum evaporation. (4) is formed.
反応性スパッタリングによって酸化物 膜を形成することもできる。Oxide by reactive sputtering A film can also be formed.
(b)
(d) プラズマ灰化処理等によって残っているレジ
スト部を除去すると、その上部の強磁性薄M(4)も除
去される。こうすることにより、第1図に示したような
単磁区微粒子(2)が形或される.
(作 用)
この発明においては、単磁区微粒子の配列によって、1
09bit/−オーダーの超高記録密度が実現され、
また、書き換えも可能となる。また、雑音が少なく、減
磁作用の小さい記録媒体が得られる.記録続出時の信号
強度も大きくなる。(b) (d) When the remaining resist portion is removed by plasma ashing or the like, the ferromagnetic thin layer M(4) above it is also removed. By doing this, single-domain fine particles (2) as shown in Figure 1 are formed. (Function) In this invention, by the arrangement of single magnetic domain fine particles, 1
An ultra-high recording density of 0.09 bit/- order has been achieved,
Moreover, rewriting is also possible. Furthermore, a recording medium with less noise and less demagnetization effect can be obtained. The signal strength also increases when recording continues.
〈実施例)
この発明の磁気記録媒体としては、たとえば以下のもの
を例示することができる.
すなわち、円盤状のガラスまたは樹脂製の非磁性基板(
1)の上に、Fe−Co合金の強磁性物質からなる単磁
区微粒子(2)を形成する。この時の単磁区微粒子(2
)の巾(W)を100r+n+ 、その長さ(』)を2
00nn 、高さ(h)を100nnとする.
また間隔(S )(S2)は、各々100nn、1
100nI1とする.
この配列は、レジスト膜として厚さ500r+nのPM
MA (ポリメチルメタクリレート)を用い、電子ビー
ム描画プロセスによって形成する.このようにして形成
した磁気記録媒体は、抗磁力として約4KOeの値を示
し、記録密度は約2 X 1 09bit/clに達す
る.ディジタル信号の記録媒体として、コンピュータ用
の磁気ディスク、ディジタル方式のビデオディスク等に
好適に用いることができる.<Example> Examples of the magnetic recording medium of the present invention include the following. In other words, a disc-shaped glass or resin non-magnetic substrate (
Single-domain fine particles (2) made of a ferromagnetic material of Fe--Co alloy are formed on 1). At this time, single magnetic domain fine particles (2
) width (W) is 100r+n+, its length ('') is 2
00nn, and the height (h) is 100nn. Also, the spacing (S) (S2) is 100nn and 1100nI1, respectively. This arrangement consists of PM with a thickness of 500r+n as a resist film.
It is formed using MA (polymethyl methacrylate) by an electron beam lithography process. The magnetic recording medium thus formed exhibits a coercive force of about 4 KOe and a recording density of about 2 x 109 bits/cl. As a recording medium for digital signals, it can be suitably used for magnetic disks for computers, digital video disks, etc.
第1図は、この発明の磁気記録媒体を例示した拡大斜視
図である.第2図は、その製造プロセスの一例を示した
工程断面図である.FIG. 1 is an enlarged perspective view illustrating the magnetic recording medium of the present invention. Figure 2 is a cross-sectional view showing an example of the manufacturing process.
Claims (4)
非磁性基板上に対称配列してなることを特徴とする磁気
記録媒体。(1) A magnetic recording medium comprising single-domain fine particles of a constant shape made of a ferromagnetic material arranged symmetrically on a non-magnetic substrate.
成してなる請求項(1)記載の磁気記録媒体。(2) The magnetic recording medium according to claim (1), wherein single-domain fine particles are formed by a microbeam drawing process.
してなる請求項(1)記載の磁気記録媒体。(3) The magnetic recording medium according to claim (1), wherein the planar length of the single magnetic domain fine particles is 2 to 10 times the width thereof.
なる請求項(1)記載の磁気記録媒体。(4) The magnetic recording medium according to claim (1), wherein the mutual spacing of the single magnetic domain fine particles is approximately equal to the width thereof.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15589789A JPH0628093B2 (en) | 1989-06-20 | 1989-06-20 | Magnetic recording medium |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15589789A JPH0628093B2 (en) | 1989-06-20 | 1989-06-20 | Magnetic recording medium |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0322211A true JPH0322211A (en) | 1991-01-30 |
JPH0628093B2 JPH0628093B2 (en) | 1994-04-13 |
Family
ID=15615901
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP15589789A Expired - Lifetime JPH0628093B2 (en) | 1989-06-20 | 1989-06-20 | Magnetic recording medium |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0628093B2 (en) |
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EP1975703A2 (en) | 2007-03-30 | 2008-10-01 | Fujifilm Corporation | Mold structure, imprinting method using the same, magnetic recording medium and production method thereof |
EP1975704A2 (en) | 2007-03-30 | 2008-10-01 | Fujifilm Corporation | Mold structure, imprinting method using the same, magnetic recording medium and production method thereof |
EP2109100A1 (en) | 2008-04-09 | 2009-10-14 | Fujitsu Limited | Magnetic recording medium and magnetic recording and reproducing device |
JP2010003408A (en) * | 2004-11-04 | 2010-01-07 | Tdk Corp | Patterned magnetic recording medium |
US7850441B2 (en) | 2006-12-05 | 2010-12-14 | Fujifilm Corporation | Mold structure |
US7900341B2 (en) | 2008-02-29 | 2011-03-08 | Hitachi, Ltd. | Method of manufacturing hard disk recording device using patterned medium |
US7998605B2 (en) | 2005-09-28 | 2011-08-16 | Hitachi Global Storage Technologies Netherlands B.V. | Magnetic recording medium and method for production thereof |
US8225843B2 (en) | 2007-06-28 | 2012-07-24 | Sumitomo Metal Industries, Ltd. | Continuous casting mold and continuous casting method of round billet |
US8329249B2 (en) | 2008-06-04 | 2012-12-11 | Fujitsu Limited | Magnetic recording medium, magnetic recording and reproducing device with magnetic recording medium, and magnetic-recording-medium manufacturing method |
US9053733B2 (en) | 2010-04-14 | 2015-06-09 | Kabushiki Kaisha Toshiba | Magnetic recording medium with magnetic portions of different orientations and method of manufacturing the same |
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JP2009245559A (en) | 2008-03-31 | 2009-10-22 | Fujifilm Corp | Master carrier for magnetic transfer and magnetic recording medium |
JP5422912B2 (en) | 2008-04-30 | 2014-02-19 | 富士通株式会社 | Magnetic recording medium, method for manufacturing the same, and magnetic recording / reproducing apparatus |
-
1989
- 1989-06-20 JP JP15589789A patent/JPH0628093B2/en not_active Expired - Lifetime
Cited By (12)
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US6602620B1 (en) | 1998-12-28 | 2003-08-05 | Kabushiki Kaisha Toshiba | Magnetic recording apparatus, magnetic recording medium and manufacturing method thereof |
JP2010003408A (en) * | 2004-11-04 | 2010-01-07 | Tdk Corp | Patterned magnetic recording medium |
US7998605B2 (en) | 2005-09-28 | 2011-08-16 | Hitachi Global Storage Technologies Netherlands B.V. | Magnetic recording medium and method for production thereof |
US7850441B2 (en) | 2006-12-05 | 2010-12-14 | Fujifilm Corporation | Mold structure |
EP1975703A2 (en) | 2007-03-30 | 2008-10-01 | Fujifilm Corporation | Mold structure, imprinting method using the same, magnetic recording medium and production method thereof |
EP1975704A2 (en) | 2007-03-30 | 2008-10-01 | Fujifilm Corporation | Mold structure, imprinting method using the same, magnetic recording medium and production method thereof |
US8225843B2 (en) | 2007-06-28 | 2012-07-24 | Sumitomo Metal Industries, Ltd. | Continuous casting mold and continuous casting method of round billet |
US8397792B2 (en) | 2007-06-28 | 2013-03-19 | Sumitomo Metal Industries, Ltd. | Continuous casting mold and continuous casting method of round billet |
US7900341B2 (en) | 2008-02-29 | 2011-03-08 | Hitachi, Ltd. | Method of manufacturing hard disk recording device using patterned medium |
EP2109100A1 (en) | 2008-04-09 | 2009-10-14 | Fujitsu Limited | Magnetic recording medium and magnetic recording and reproducing device |
US8329249B2 (en) | 2008-06-04 | 2012-12-11 | Fujitsu Limited | Magnetic recording medium, magnetic recording and reproducing device with magnetic recording medium, and magnetic-recording-medium manufacturing method |
US9053733B2 (en) | 2010-04-14 | 2015-06-09 | Kabushiki Kaisha Toshiba | Magnetic recording medium with magnetic portions of different orientations and method of manufacturing the same |
Also Published As
Publication number | Publication date |
---|---|
JPH0628093B2 (en) | 1994-04-13 |
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