JP4621899B2 - Magnetic media - Google Patents
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この出願の発明は、基材表面に高配向磁性薄膜を形成した磁気媒体に関するもので、具体的には磁気記録媒若しくは微小回路の磁界発生用磁石（これらを総称して磁気媒体という）に関する。 The invention of this application relates to a magnetic medium having a highly oriented magnetic thin film formed on the surface of a substrate, and specifically to a magnetic recording medium or a magnet for generating a magnetic field of a microcircuit (collectively referred to as a magnetic medium).
近年の情報化社会の発展に伴い、大量の情報を処理および記憶することの可能な超高密度磁気記録媒体の開発が切望されている。超高密度磁気記録媒体に必要とされる特性には、
１）磁気記録媒体を構成する磁性体が磁気的に孤立した微粒子構造であること、
２）磁性体微粒子が熱擾乱に打ち勝つこと、そして、
３）一方向に配向していることが挙げられる。
これらの特性を実現して磁気記憶媒体を製造する方法として、化学的な方法および機械的な方法が公知である。化学的な方法においては、有害廃棄物、結晶配向制御、製造コスト等の問題がある。また、リソグラフィーなどに代表される機械的方法においては、製造時間およびコストの問題が技術的課題として残されており、いずれの方法においても工業的に大量生産することは困難である。
With the development of the information society in recent years, development of an ultra-high density magnetic recording medium capable of processing and storing a large amount of information is eagerly desired. The properties required for ultra high density magnetic recording media include:
1) The magnetic material constituting the magnetic recording medium has a magnetically isolated fine particle structure,
2) The magnetic fine particles overcome the thermal disturbance, and
3) It may be oriented in one direction.
Chemical methods and mechanical methods are known as methods for producing magnetic storage media by realizing these characteristics. Chemical methods have problems such as hazardous waste, crystal orientation control, and manufacturing costs. Moreover, in the mechanical method represented by lithography etc., the problem of manufacturing time and cost remains as a technical subject, and it is difficult to industrially mass-produce in any method.
磁気記録媒体の高密度化を行うためには、強磁性微粒子のサイズを小さくする必要がある。しかし、強磁性微粒子のサイズを小さくすることで、熱擾乱による超常磁性化の影響を受けやすくなり、その結果、磁気記録が不安定となるという問題がある。 In order to increase the density of the magnetic recording medium, it is necessary to reduce the size of the ferromagnetic fine particles. However, by reducing the size of the ferromagnetic fine particles, there is a problem that the magnetic recording is likely to be affected by superparamagnetization due to thermal disturbance, and as a result, magnetic recording becomes unstable.
一方、Ｌ１0構造を有するＦｅＰｔ規則相は７×１０6Ｊ／ｍ3という高い一軸磁気異方性を有するためにナノサイズの超微細粒子であっても強磁性を維持することができ、このため次世代の超高密度磁気記録媒体用材料として期待されている。
この材料で単磁区粒子を生成した場合においては、磁化回転による保磁力２Ｋu／Ｍsは１２０ｋＯｅにも達するものと理論的には考えられるが、現実には、そのような高い保磁力は実現することは不可能である。
On the other hand, since the FePt ordered phase having the L1 0 structure has a high uniaxial magnetic anisotropy of 7 × 10 6 J / m 3 , it can maintain ferromagnetism even with nano-sized ultrafine particles. Therefore, it is expected as a material for the next generation ultra high density magnetic recording medium.
When single-domain particles are generated with this material, the coercive force 2K u / M s due to magnetization rotation is theoretically considered to reach 120 kOe, but in reality, such a high coercive force is realized. It is impossible to do.
そこで、この出願の発明は、以上の通りの事情に鑑みてなされたものであり、２０ｋＯｅ以上の保磁力を持つ磁気媒体を提供することを目的とする。 Therefore, the invention of this application has been made in view of the circumstances as described above, and an object thereof is to provide a magnetic medium having a coercive force of 20 kOe or more.
この出願の発明は、上記の課題を解決するものとして、基材表面に高配向磁性薄膜を形成した磁気媒体であって、前記薄膜が、温度が６５０℃以上に加熱された状態の基板上に、スパッターリングにより成膜され、合金組成がＦｅ ｘ Ｐｔ １−ｘ であってｘの範囲が０．４＜ｘ＜０．６のＬ１0構造を有する島状微結晶が相互に不連続に並置され、かつ、前記島状結晶の磁化方位が揃えられてなることを特徴とする磁気媒体を提供する。 The invention of this application is a magnetic medium in which a highly oriented magnetic thin film is formed on the surface of a base material, and the thin film is heated on a substrate heated to 650 ° C. or higher. , deposited by sputtering, the island-shaped microcrystals discontinuously juxtaposed to each other with an L1 0 structure was in the range of x is 0.4 <x <0.6 in the alloy composition is Fe x Pt 1-x In addition, a magnetic medium is provided in which the magnetization directions of the island-like crystals are aligned .
この出願の発明によって、２０ｋＯｅ以上の保磁力を持つ磁気媒体を提供することができた。 According to the invention of this application, a magnetic medium having a coercive force of 20 kOe or more can be provided.
この出願の発明は、上記のとおりの特徴をもつものであるが、以下に、その実施の形態について説明する。 The invention of this application has the features as described above, and an embodiment thereof will be described below.
この出願の発明は、磁気的に孤立した微粒子構造を備えた高配向磁性薄膜をもつ磁気媒体であり、その製造方法は以下の通りである。
薄膜が（１）核生成→（２）島状→（３）連続状という初期成長過程を経て成長することに着目し、基板温度を上昇させて原子拡散の活発な温度領域において、基板上に合金薄膜をスパッタ成膜するものである。このとき、合金薄膜を形成する合金微粒子は島状となって形成される。
The invention of this application is a magnetic medium having a highly oriented magnetic thin film having a magnetically isolated fine particle structure, and the manufacturing method thereof is as follows.
Paying attention to the fact that the thin film grows through the initial growth process of (1) nucleation → (2) island shape → (3) continuous, the substrate temperature is raised and the atomic temperature is increased on the substrate in the active temperature region. An alloy thin film is formed by sputtering. At this time, the alloy fine particles forming the alloy thin film are formed in an island shape.
また、基板とエピタキシャル成長させることにより、膜面に垂直方向に一軸磁気異方性を有するＬ１0構造を持つ合金薄膜が製造される。 Further, by the substrate and the epitaxial growth, the alloy thin film having an L1 0 structure having uniaxial magnetic anisotropy in the direction perpendicular to the film plane is produced.
基板上に成膜される合金薄膜は、ＦｅおよびＣｏのうちの少なくとも１種類の金属と、ＰｔおよびＰｄのうちの少なくとも１種類の金属との合金薄膜からなるものである。 The alloy thin film formed on the substrate is composed of an alloy thin film of at least one kind of metal of Fe and Co and at least one kind of metal of Pt and Pd.
高保磁力を示す合金薄膜を形成するためには、高い一軸磁気異方性を有する規則化したＬ１0型構造を有する合金を生成する必要がある。工業的に広く用いられているスパッタ法や蒸着法などの気相急冷法などにより合金薄膜を成膜すると、磁気異方性の小さい不規則相であるｆｃｃ合金相の薄膜が形成されることになる。完全に規則化した合金微粒子を島状に成長させるためには、スバッタ成膜時の基板温度を６５０℃以上に維持する必要がある。 To form an alloy thin film exhibiting a high coercive force, it is necessary to generate an alloy having ordered the L1 0 type structure having a high uniaxial magnetic anisotropy. When an alloy thin film is formed by a vapor phase quenching method such as sputtering or vapor deposition which is widely used in industry, a thin film of an fcc alloy phase, which is an irregular phase with small magnetic anisotropy, is formed. Become. In order to grow completely ordered alloy fine particles in an island shape, it is necessary to maintain the substrate temperature at 650 ° C. or higher during the sputtering process.
高保磁力を示す合金薄膜を合成するには、島状の合金微粒子の磁化過程が磁壁移動よりも磁化回転が支配的となる組織を有する必要があることから、合金薄膜の膜厚が４５ｎｍ以下となるようにスパッタ成膜が行われる。 In order to synthesize an alloy thin film exhibiting a high coercive force, the magnetization process of island-shaped alloy fine particles needs to have a structure in which the magnetization rotation is more dominant than the domain wall movement. Sputter film formation is performed as follows.
高保磁力を有する高配向磁性薄膜を超高密度磁気記録媒体用途に利用するためには島状の合金微粒子の粒径を微小とする必要がある。金属の表面エネルギーは融点に比例し、表面エネルギーの大きい金属はぬれ性が小さいので、膜厚を例えば２０ｎｍ以下となるように薄く成膜すれば、合金微粒子の形状は小さな島状となる。この島状の合金微粒子上に、さらに合金を成膜することで、島状の合金微粒子を初期成長核として作用させ、島状の合金微粒子を微小に形成することが可能となる。 In order to use a highly oriented magnetic thin film having a high coercive force for an ultra-high density magnetic recording medium, it is necessary to make the particle size of the island-shaped alloy fine particles minute. The surface energy of the metal is proportional to the melting point, and the metal having a large surface energy has low wettability. Therefore, if the film is thinly formed so that the film thickness is, for example, 20 nm or less, the shape of the alloy fine particles becomes a small island shape. By further forming an alloy film on the island-shaped alloy fine particles, the island-shaped alloy fine particles can act as initial growth nuclei, and the island-shaped alloy fine particles can be formed minutely.
スパッタリングそのもののプロセスについては公知のものをはじめとして各種の装置や条件を適宜に採用することができる。ターゲットとしても、たとえば合金を構成する各々の純金属を用いた同時スパッタリングでもよく、組成が予備的に調整された合金ターゲットを用いてもよい。 As for the process of sputtering itself, various apparatuses and conditions including known ones can be appropriately employed. As the target, for example, simultaneous sputtering using pure metals constituting the alloy may be used, or an alloy target whose composition is preliminarily adjusted may be used.
基板上に成膜される合金薄膜がたとえばＦｅＰｔ合金薄膜とした場合、ＦｅＰｔ合金薄膜におけるＦｅＰｔ相の合金組成比がＦｅxＰｔ1-x（ただし、０．４＜ｘ＜０．６）となるように成膜を行うことが好ましい。合金組成比をこの範囲に設定したとき、成膜されるＦｅＰｔ合金薄膜は、高い一軸磁気異方性定数を示し、極めて高い保磁力が得られる。 When the alloy thin film formed on the substrate is, for example, an FePt alloy thin film, the FePt phase alloy composition ratio in the FePt alloy thin film is Fe x Pt 1-x (where 0.4 <x <0.6). It is preferable to perform film formation as described above. When the alloy composition ratio is set within this range, the formed FePt alloy thin film exhibits a high uniaxial magnetic anisotropy constant and an extremely high coercive force is obtained.
また、この出願の発明の高配向磁性薄膜の製造方法においては、基板上に成膜される合金薄膜上に、高飽和磁化磁性材料を成膜してもよい。高飽和磁化磁性材料としては、ＦｅまたはＦｅＣｏの内のいずれかが適宜に選択される。このように高保磁力を有する合金薄膜と高飽和磁化軟磁性粒子とを強磁性的にカップリングさせることで、高い最大エネルギー積を有する磁石が生成される。 In the method for producing a highly oriented magnetic thin film of the invention of this application, a highly saturated magnetic material may be formed on an alloy thin film formed on a substrate. As the highly saturated magnetic material, either Fe or FeCo is appropriately selected. Thus, a magnet having a high maximum energy product is generated by ferromagnetically coupling the alloy thin film having a high coercive force and the high saturation magnetization soft magnetic particles.
さらに、この出願の発明の高配向磁性薄膜の製造方法においては、基板の結晶配向の制御を行うことで、基板上に成膜される合金薄膜に磁気異方性を付与する。磁気記録媒体には、磁化容易軸を面内に配向させた面内磁気記録媒体と磁化容易軸を基板に対して垂直方向に配向させた垂直磁気記録媒体との２種類があり、基板を、ＭｇＯ（１１０）、ＮａＣｌ（１１０）、ＧａＡｓ（１１０）、および、Ｓｉ（１１０）のうちのいずれかから選択することで、磁化容易軸を面内に配向させることが可能となり、また、基板を、ＮａＣｌ（００１）、ＧａＡｓ（００１）、および、Ｓｉ（００１）のうちのいずれかから選択することで、磁化容易軸を垂直方向に配向させることが可能となる。 Furthermore, in the method for producing a highly oriented magnetic thin film of the invention of this application, magnetic anisotropy is imparted to the alloy thin film formed on the substrate by controlling the crystal orientation of the substrate. There are two types of magnetic recording media: an in-plane magnetic recording medium in which the easy magnetization axis is aligned in the plane and a perpendicular magnetic recording medium in which the easy magnetization axis is aligned in a direction perpendicular to the substrate. By selecting any one of MgO (110), NaCl (110), GaAs (110), and Si (110), it becomes possible to orient the easy axis of magnetization in the plane, and By selecting any one of NaCl (001), GaAs (001), and Si (001), the easy axis of magnetization can be oriented in the vertical direction.
この出願の発明においては、ＭｇＯ（００１）基板を（００１）面から僅かに傾斜して切り出したｍｉｓｃｕｔ基板において２次元の原子ステップを作成したものを基板とし、この基板上に合金薄膜を成膜することで、２次元的に規則性を持って配列した自己組織パターン媒体を作成してもよい。 In the invention of this application, a miscut substrate obtained by cutting a MgO (001) substrate with a slight inclination from the (001) plane is used as a substrate, and an alloy thin film is formed on this substrate. By doing so, a self-organized pattern medium arranged two-dimensionally with regularity may be created.
この出願の発明である高配向磁性薄膜の製造方法においては、下地を必要としないため、１段階でのスパッタでＦｅＰｔ微粒子を形成している点、さらに蒸着法とは異なり、工業的な生産が容易なスパッタ法を用いている点が従来技術との大きな相違点である。しかも、このような簡便な手法により４０ｋＯｅ以上の高い保磁力を実現している。 In the manufacturing method of the highly oriented magnetic thin film which is the invention of this application, since an underlayer is not required, FePt fine particles are formed by sputtering in one step, and further, unlike the vapor deposition method, industrial production The point of using an easy sputtering method is a big difference from the prior art. Moreover, a high coercive force of 40 kOe or more is realized by such a simple method.
この出願の発明は、以上の特徴を持つものであるが、以下に実施例を示し、さらに具体的に説明する。 The invention of this application has the above-described features, and will be described more specifically with reference to examples.
ヘリコンスパッタ装置（ＵＬＶＡＣ社製 ＭＢ９９−０００１）を用い、ＦｅとＰｔをターゲットとしてＦｅＰｔ薄膜を成膜した。成膜の条件については、雰囲気ガスにはＡｒガスを使用し、真空度は、到達が５×１０-10Ｔｏｒｒ、成膜時が１．４×１０-3Ｔｏｒｒであって、スパッタ投入電力はＦｅターゲットについては７０Ｗ、Ｐｔターゲットについては２７Ｗとした。 Using a helicon sputtering apparatus (MB99-0001 manufactured by ULVAC), an FePt thin film was formed using Fe and Pt as targets. Regarding the conditions for film formation, Ar gas is used as the atmospheric gas, the degree of vacuum is 5 × 10 −10 Torr at the time of film formation, and 1.4 × 10 −3 Torr at the time of film formation. The Fe target was 70 W, and the Pt target was 27 W.
図１は、その際の膜厚を２０ｎｍとし、成膜時の基板温度を５００〜７００℃の間で変化させた時の磁化曲線の変化である。６５０℃以上の磁化曲線の領域において、保磁力が急激に増加していることから、高保磁力を有するＦｅＰｔ薄膜は６５０℃以上で成膜することが必要であることがわかる。 FIG. 1 shows changes in the magnetization curve when the film thickness at that time is 20 nm and the substrate temperature during film formation is changed between 500-700 ° C. Since the coercive force increases rapidly in the region of the magnetization curve of 650 ° C. or higher, it can be seen that the FePt thin film having a high coercive force needs to be formed at 650 ° C. or higher.
図２は、ＭｇＯ（００１）単結晶基板上に基板温度を６５０℃として成膜された、膜厚が２０ｎｍのＦｅＰｔ薄膜のＸ線回折パターンである。２θ＝２８°付近に超格子反射である（００１）からの反射が観測される、また、２θ＝５８°付近に（００２）からの反射が、また２θ＝７８°付近に超格子反射である（００３）からの反射が観測される。超格子反射線が明療に観測されることから規則化したＦｅＰｔが形成されていることがわかる。また規則度は０．９５±０．０５である。このＸ線回折パターンよりＦｅＰｔ膜が基板とＭｇＯ（００１）／／ＦｅＰｔ（００１）の方位関係を持って成長していることがわかる。 FIG. 2 is an X-ray diffraction pattern of a 20 nm thick FePt thin film formed on a MgO (001) single crystal substrate at a substrate temperature of 650 ° C. Reflection from (001) which is a superlattice reflection is observed near 2θ = 28 °, reflection from (002) is near 2θ = 58 °, and superlattice reflection is near 2θ = 78 °. Reflection from (003) is observed. It can be seen that ordered FePt is formed from the fact that the superlattice reflection lines are clearly observed. The degree of order is 0.95 ± 0.05. From this X-ray diffraction pattern, it can be seen that the FePt film grows with the orientation relationship of MgO (001) // FePt (001) with the substrate.
図３は、基板温度を６５０℃として成膜された膜厚２０ｎｍのＦｅＰｔ薄膜の膜面内方向および膜垂直方向の磁化曲線である。これらの磁化曲線より膜面内方向が磁化困難軸であり、また、膜垂直方向が磁化容易軸であることがわかる。さらに、膜垂直方向の保磁力は約２５ｋＯｅであり、この値は従来報告されている連続膜の保磁力と比較して２倍以上も大きな値である。 FIG. 3 is a magnetization curve in the in-plane direction and in the film perpendicular direction of a 20 nm thick FePt thin film formed at a substrate temperature of 650 ° C. From these magnetization curves, it can be seen that the in-plane direction of the film is the hard axis of magnetization, and the perpendicular direction of the film is the easy axis of magnetization. Furthermore, the coercive force in the direction perpendicular to the film is about 25 kOe, which is more than twice as large as the conventionally reported coercivity of a continuous film.
図４は、基板温度７００℃で成膜された膜厚５〜２００ｎｍのＦｅＰｔ薄膜の膜垂直方向の磁化曲線である。５ｎｍの膜厚のＦｅＰｔ薄膜では約４６ｋＯｅの保磁力を示している。膜厚が５ｎｍから４５ｎｍへ増加すると、保磁力は４６ｋＯｅから減少するものの、約２５ｋＯｅ以上の大きな値を示している。膜厚が５０ｎｍ以上の領域で、磁化曲線は急激に変化を示し、保磁力も急激に変化する。これは４５ｎｍ以下の薄膜と５０ｎｍ以上の薄膜との間に、磁化過程に関して大きく異なることを示すものである。以上より、膜厚が小さい場合において、薄膜は非常に大きな保磁力を示すことが明らかとなった。 FIG. 4 is a magnetization curve in the perpendicular direction of a 5-200 nm thick FePt thin film formed at a substrate temperature of 700 ° C. The 5 nm thick FePt thin film exhibits a coercive force of about 46 kOe. When the film thickness is increased from 5 nm to 45 nm, the coercive force decreases from 46 kOe, but shows a large value of about 25 kOe or more. In the region where the film thickness is 50 nm or more, the magnetization curve changes abruptly and the coercive force also changes abruptly. This indicates that the magnetization process differs greatly between a thin film of 45 nm or less and a thin film of 50 nm or more. From the above, it has been clarified that the thin film exhibits a very large coercive force when the film thickness is small.
図５は、ＦｅＰｔ薄膜の膜面に対して垂直方向の磁化曲線より求められた保磁力のＦｅＰｔ膜厚依存性を示す。保磁力は、５ｎｍの約４６ｋＯｅから４５ｎｍの約２５ｋＯｅへと減少し、さらに、膜厚が５０ｎｍになると、保磁力が急激に約２．５ｋＯｅにまで減少する。薄膜表面の電気抵抗の測定を行った結果、膜厚が４５ｎｍでは８００ＭΩとなり、ＦｅＰｔ微粒子の形状は電気的に孤立しており、また、膜厚が５０ｎｍでは８００Ωとなっていることから、ＦｅＰｔ微粒子の形状は連続状となっているものと考えられる。 FIG. 5 shows the dependence of the coercivity obtained from the magnetization curve perpendicular to the film surface of the FePt thin film on the FePt film thickness. The coercive force decreases from about 46 kOe of 5 nm to about 25 kOe of 45 nm. Further, when the film thickness is 50 nm, the coercive force is rapidly reduced to about 2.5 kOe. As a result of measuring the electric resistance on the surface of the thin film, the FePt fine particle is 800 MΩ when the film thickness is 45 nm, the shape of the FePt fine particle is electrically isolated, and is 800 Ω when the film thickness is 50 nm. The shape of is considered to be continuous.
図６および図７は、電子顕微鏡により観察したＦｅＰｔ薄膜の微細構造である。それぞれにおいて、ＦｅＰｔ薄膜の膜厚は、５、１０、１５、２０、４５、５０、６０、１００ｎｍである。ＦｅＰｔ薄膜の膜厚が、５、１０、１５および２０ｎｍの場合には、ＦｅＰｔ微粒子の形状が島状になっていることが確認され、個々の島はお互いに完全に孤立していることから、これらは磁気的にも孤立した粒子であると考えられる。膜厚の増加により島の合体が観察され、ＦｅＰｔ薄膜の膜厚が４５ｎｍになると、それぞれの島は完全に孤立しているものの、一部の島が連続化する部分も見られる。ＦｅＰｔ薄膜の膜厚が５０ｎｍの場合、島の連続化はさらに進み、経路ができるものの、一部には完全に孤立した島が存在する。ＦｅＰｔ膜厚が、６０ｎｍになると、ＦｅＰｔ膜全体にわたる経路が構成される。 6 and 7 show the microstructure of the FePt thin film observed with an electron microscope. In each case, the thickness of the FePt thin film is 5, 10, 15, 20, 45, 50, 60, 100 nm. When the film thickness of the FePt thin film is 5, 10, 15 and 20 nm, it is confirmed that the shape of the FePt fine particles is an island shape, and the individual islands are completely isolated from each other. These are considered to be magnetically isolated particles. When the film thickness is increased, island coalescence is observed. When the film thickness of the FePt thin film reaches 45 nm, although the islands are completely isolated, some islands are continuous. When the film thickness of the FePt thin film is 50 nm, the continuation of islands further proceeds and a path is formed, but there are islands that are completely isolated. When the FePt film thickness is 60 nm, a path over the entire FePt film is formed.
以上で示した微細構造観察により、ＦｅＰｔ薄膜の膜厚が４５ｎｍから５０ｎｍへと増加するときに観測された保磁力の急激な減少が、膜構造が島状から連続状へ変化することに起因していることがわかる。この臨界膜厚は、磁化反転を支配する機構が磁化回転から磁壁の移動に遷移する領域に対応しているものと考えられる。この微細構造観察より、この高保磁力ＦｅＰｔ薄膜は、適当な基板を用いることにより面内磁気記録媒体及び垂直磁気記録媒体への応用が可能であることがわかる。さらに、島状構造を有している高保磁力ＦｅＰｔに、ＦｅやＦｅＣｏなどの高飽和磁化軟磁性材料を成膜することで、硬磁性相粒と軟磁性相粒との間に強磁性的なカップリングが発生し、高い最大エネルギー積を有する薄膜磁石の実現が可能性となる。また、膜厚５ｎｍの薄膜においては、 The rapid observation of the coercive force observed when the film thickness of the FePt thin film increases from 45 nm to 50 nm by the fine structure observation described above is attributed to the film structure changing from an island shape to a continuous shape. You can see that This critical film thickness is considered to correspond to the region where the mechanism governing magnetization reversal transitions from magnetization rotation to domain wall movement. From this fine structure observation, it can be seen that this high coercive force FePt thin film can be applied to an in-plane magnetic recording medium and a perpendicular magnetic recording medium by using an appropriate substrate. Further, by forming a high saturation magnetization soft magnetic material such as Fe or FeCo on the high coercive force FePt having an island-like structure, a ferromagnetic layer is formed between the hard magnetic phase grains and the soft magnetic phase grains. Coupling occurs and it is possible to realize a thin film magnet having a high maximum energy product. In a thin film having a thickness of 5 nm,
面を辺とする、ほぼ正方形の自己組織パターンが形成していることが観察され、しかも、この配列が基板の原子ステップに沿っていることが判断される。このことから、ｍｉｓｃｕｔ基板上に、ＦｅＰｔ薄膜を成膜すると、２次元のパターン配列の形成が可能であると考えられる。
It is observed that a substantially square self-organized pattern having a side as a side is formed, and it is determined that this arrangement follows the atomic steps of the substrate. From this, it is considered that when a FePt thin film is formed on a miscut substrate, a two-dimensional pattern arrangement can be formed.
図８は、膜厚を１５ｎｍとしてＭｇＯ（００１）およびＭｇＯ（１１０）単結晶基板上に作製された薄膜の電子顕微鏡により観察した微細構造である。ＭｇＯ（００１）単結晶基板上のＦｅＰｔは FIG. 8 shows the microstructure of a thin film formed on an MgO (001) and MgO (110) single crystal substrate with a film thickness of 15 nm, which was observed with an electron microscope. FePt on MgO (001) single crystal substrate is
面を辺とするほぼ正方形の自己組織パターンが形成されているが、ＭｇＯ（１１０）単結晶基板上のＦｅＰｔは＜-１１０＞方向にのびた自己組織パターンが形成されている。この微細構造観察結果から、適当な基板を選択することにより任意の方向にそろった自己組織パターンが形成可能であることがわかる。
A substantially square self-organized pattern having a side as a side is formed, but the FePt on the MgO (110) single crystal substrate has a self-organized pattern extending in the <−110> direction. From this fine structure observation result, it is understood that a self-organized pattern aligned in an arbitrary direction can be formed by selecting an appropriate substrate.
以上の実施例を踏まえた上で、表面温度を７００℃とした基板上に膜厚を４５ｎｍ以下として成膜されたＦｅＰｔ薄膜は、約２５ｋＯｅ以上の非常に大きな保磁力を示すことが明らかとなった。これは、面内および垂直磁気記録媒体及び強力な薄膜磁石への応用が可能であるものと考えられる。 Based on the above examples, it has become clear that an FePt thin film formed on a substrate having a surface temperature of 700 ° C. with a film thickness of 45 nm or less exhibits a very large coercive force of about 25 kOe or more. It was. This is considered to be applicable to in-plane and perpendicular magnetic recording media and strong thin film magnets.
この出願の発明の磁気媒体は、高い結晶磁気異方性を持つ材料として知られるＬ１0構造をもつ合金相の組織を島状にすることで、磁気記録媒体や薄膜磁石へ応用するのに極めて有効な技術といえる。 Magnetic media of the invention of this application, by the structure of the alloy phase having an L1 0 structure known as a material having a high crystal magnetic anisotropy in an island shape, extremely to be applied to a magnetic recording medium or a thin film magnet This is an effective technology.
この出願の発明の高配向磁性薄膜の製造方法により、自己組織化を利用して高保磁力を示す高配向磁性合金薄膜の生成が可能となり、従来技術である化学的方法および機械的方法と比しても簡便あることから、高配向磁性薄膜の大量生産に有利であると考えられる。情報ストレージデバイスの中でもハードディスク装置は特に重要なデバイスのひとつとして位置づけられており、更なる大容量記憶を実現する磁気記録媒体が望まれており、さらに微小回路の磁界発生用磁石として大いに期待されることからも、この出願の発明の実用化が強く期待される。 The manufacturing method of the highly oriented magnetic thin film of the invention of this application makes it possible to produce a highly oriented magnetic alloy thin film exhibiting a high coercive force by utilizing self-organization, compared with the conventional chemical and mechanical methods. However, since it is simple, it is considered advantageous for mass production of highly oriented magnetic thin films. Among information storage devices, the hard disk drive is positioned as one of the most important devices, and a magnetic recording medium that realizes further large-capacity storage is desired. Further, it is highly expected as a magnetic field generating magnet for a microcircuit. For this reason, the practical application of the invention of this application is strongly expected.
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