JP4232564B2 - Perpendicular magnetic recording medium - Google Patents
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本発明は、とくに、ＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層との間に網目構造層をごく薄く形成した垂直磁気記録媒体に関するものである。 The present invention particularly relates to a perpendicular magnetic recording medium in which a network structure layer is extremely thinly formed between a CoZr amorphous soft magnetic underlayer and a CoCr perpendicular recording layer.
一般的に、垂直磁気記録は、映像，音声，ディジタルデータなどの情報信号を垂直記録層上に略垂直に記録することで、現行の長手記録よりも情報信号を高密度に記録ができるので注目されている。 In general, in perpendicular magnetic recording, information signals such as video, audio, and digital data are recorded almost vertically on a perpendicular recording layer, so that information signals can be recorded at a higher density than current longitudinal recording. Has been.
上記した垂直磁気記録に適用される垂直磁気記録媒体は、例えば垂直記録層として成膜したＣｏＣｒ系合金薄膜が、強い垂直磁気異方性を有し良好な磁気記録特性が得られることから最も精力的に検討されている。この際、ＣｏＣｒ系合金薄膜（ＣｏＣｒ系垂直記録層）は最密六方晶構造（ｈｃｐ）からなる結晶構造をとり、磁化容易軸であるｃ軸が薄膜面に対して略垂直方向に配向することにより強い垂直磁気異方性が得られる。 The perpendicular magnetic recording medium applied to the perpendicular magnetic recording described above is most vigorous because, for example, a CoCr alloy thin film formed as a perpendicular recording layer has strong perpendicular magnetic anisotropy and good magnetic recording characteristics can be obtained. Has been considered. At this time, the CoCr-based alloy thin film (CoCr-based perpendicular recording layer) has a crystal structure composed of a close-packed hexagonal crystal structure (hcp), and the c-axis, which is the easy axis of magnetization, is oriented in a direction substantially perpendicular to the thin film surface. A stronger perpendicular magnetic anisotropy can be obtained.
一方、垂直磁気記録媒体への高密度化に伴って、高い信号出力、高いＳ／Ｎ（Ｓｉｇｎａｌ／Ｎｏｉｓｅ）比を得るために高い保磁力（Ｈｃ）が要求されている。この際、高保磁力化（高Ｈｃ化）は、垂直磁気異方性を強くするとともに、垂直記録層の結晶粒子を微細化することにより実現できる。これは、垂直記録層の結晶粒子が微細化すると、粒子１個が単磁区構造に近づくためである。また、垂直記録層の結晶粒子が微細化する他の利点として、媒体ノイズが低減する。このため、垂直記録層の結晶粒子の微細化は、高いＳ／Ｎ比を得るための重要な課題となっている。 On the other hand, as the density of perpendicular magnetic recording media is increased, a high coercive force (Hc) is required to obtain a high signal output and a high S / N (Signal / Noise) ratio. At this time, high coercive force (high Hc) can be realized by increasing the perpendicular magnetic anisotropy and making the crystal grains of the perpendicular recording layer fine. This is because when the crystal grains in the perpendicular recording layer are refined, one grain approaches a single domain structure. Further, as another advantage that the crystal grains of the perpendicular recording layer become finer, medium noise is reduced. For this reason, miniaturization of crystal grains in the perpendicular recording layer is an important issue for obtaining a high S / N ratio.
また、垂直記録層に記録した情報信号が熱によって減少してしまう熱緩和現象は、高密度化を阻害する要因として問題になっている。従って、強い垂直磁気異方性と高保磁力化は、記録信号の熱安定性を高める意味でも重要な要素となっている。 Further, the thermal relaxation phenomenon in which the information signal recorded on the perpendicular recording layer is reduced by heat has been a problem as a factor that hinders high density. Therefore, strong perpendicular magnetic anisotropy and high coercive force are important elements in terms of increasing the thermal stability of the recording signal.
そこで、垂直磁気記録媒体の磁気記録特性を改善するために、ＣｏＣｒ系垂直記録層の下方に下地層を形成する検討がいくつか提案されているものの、本発明者らは、ＣｏＣｒ系垂直記録層の下方に形成する下地層として、磁気記録特性が良好なＣｏＺｒ系非晶質軟磁性下地層を用いた垂直磁気記録媒体を先に提案した（例えば、特許文献１参照）。
上記の特許文献１に開示した垂直磁気記録媒体では、ガラス材などの非磁性材を用いた基板上にＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層とをこの順に積層して成膜した際に、両層内のＣｏ原子同士を直接結合させることで、両層に対して垂直配向性能が促進でき、強い垂直磁気異方性が得られると共に、更に、垂直磁気記録媒体を記録再生する時にＣｏＺｒ系非晶質軟磁性下地層が磁気回路上のヨークの一部としても作用し、垂直磁気記録媒体の記録再生効率を高める効果も併せ持つものである。 In the perpendicular magnetic recording medium disclosed in Patent Document 1, a CoZr-based amorphous soft magnetic underlayer and a CoCr-based perpendicular recording layer are laminated in this order on a substrate using a non-magnetic material such as a glass material. By directly bonding Co atoms in both layers at the time of film formation, the perpendicular alignment performance can be promoted with respect to both layers, and strong perpendicular magnetic anisotropy can be obtained. When recording / reproducing, the CoZr-based amorphous soft magnetic underlayer also acts as a part of the yoke on the magnetic circuit, and has the effect of increasing the recording / reproducing efficiency of the perpendicular magnetic recording medium.
解決しようとする問題点は、基板上にＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層とをこの順に少なくとも形成した時に、ＣｏＣｒ系垂直記録層の結晶粒子が大きく成長してしまうという現象が生じる場合があり、ＣｏＣｒ系垂直記録層の結晶粒子が大きく成長すると、保磁力（Ｈｃ）を向上させることができず、また、記録再生の際に媒体ノイズの原因になり、結果的にＳ／Ｎ比の低下を招くことになる。 The problem to be solved is that when a CoZr-based amorphous soft magnetic underlayer and a CoCr-based perpendicular recording layer are formed at least in this order on a substrate, crystal grains of the CoCr-based perpendicular recording layer grow greatly. If the CoCr-based perpendicular recording layer grows large in size, the coercive force (Hc) cannot be improved, and media noise may occur during recording and reproduction. Therefore, the S / N ratio is lowered.
そこで、垂直磁気記録媒体に対してより一層高密度化を図るために、ＣｏＺｒ系非晶質軟磁性下地層を形成してもＣｏＣｒ系垂直記録層の結晶粒子を小さくすることができる垂直磁気記録媒体が望まれている。 Therefore, in order to further increase the density of the perpendicular magnetic recording medium, perpendicular magnetic recording can reduce the crystal grains of the CoCr perpendicular recording layer even if a CoZr amorphous soft magnetic underlayer is formed. A medium is desired.
本発明は上記課題に鑑みてなされたものであり、基板上に、ＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層とを順次積層した垂直磁気記録媒体において、
前記ＣｏＺｒ系非晶質軟磁性下地層と、前記ＣｏＣｒ系垂直記録層との間に網目構造層を形成し、
前記網目構造層は、Ｃｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金材料のうちのいずれかの物質からなり、厚さが０．５〜２．３ｎｍであることを特徴とする垂直磁気記録媒体である。
The present invention has been made in view of the above problems, and in a perpendicular magnetic recording medium in which a CoZr-based amorphous soft magnetic underlayer and a CoCr-based perpendicular recording layer are sequentially laminated on a substrate ,
Said CoZr based amorphous soft magnetic underlayer, and forming a network structure layer between the CoCr-based perpendicular recording layer,
The network structure layer is made of any one of Cr, B, Nb, Mo, Ta, W, C, and alloy materials thereof, and has a thickness of 0.5 to 2.3 nm. A perpendicular magnetic recording medium.
本発明に係る垂直磁気記録媒体によれば、基板上にＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層とを順次積層し、ＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層との間に網目構造層を形成した際に、網目構造層は、Ｃｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金材料のうちのいずれかの物質からなり、厚さが０．５〜２．３ｎｍであるため、この結果、ＣｏＺｒ系非晶質軟磁性下地層とＣｏＣｒ系垂直記録層との間で磁気的結合を保ちつつ、網目構造層によりＣｏＣｒ系垂直記録層の結晶粒子を小さくすることができるので、垂直配向度が高く且つ高い保磁力（Ｈｃ）を有するＣｏＣｒ系垂直記録層が得られる。これに伴って、本発明に係る垂直磁気記録媒体を用いて情報信号を記録再生した時に、垂直磁気記録媒体の記録再生効率が高くなり、情報信号の再生出力も高くなる。また、媒体ノイズが小さく、高いＳ／Ｎ比が得られる。更に、ＣｏＣｒ系垂直記録層が保磁力（Ｈｃ）を有することによって、記録信号の熱安定性が高くなる。 According to the perpendicular magnetic recording medium of the present invention, a CoZr-based amorphous soft magnetic underlayer and a CoCr-based perpendicular recording layer are sequentially laminated on a substrate, a CoZr-based amorphous soft magnetic underlayer, and a CoCr-based When the network structure layer is formed between the perpendicular recording layer and the perpendicular recording layer , the network structure layer is made of any of Cr, B, Nb, Mo, Ta, W, C, and any of these alloy materials. since a saga 0.5～2.3Nm, this result, while maintaining the magnetic coupling between the CoZr based amorphous soft magnetic underlayer and the CoCr-based perpendicular recording layer, a CoCr-based perpendicular recording by network structure layer Since the crystal grains of the layer can be made small, a CoCr type perpendicular recording layer having a high degree of perpendicular orientation and a high coercive force (Hc) can be obtained. Accordingly, when the information signal is recorded and reproduced using the perpendicular magnetic recording medium according to the present invention, the recording and reproducing efficiency of the perpendicular magnetic recording medium is increased, and the reproduction output of the information signal is also increased. Further, the medium noise is small and a high S / N ratio can be obtained. Furthermore, since the CoCr-based perpendicular recording layer has a coercive force (Hc), the thermal stability of the recording signal is increased.
本発明に係る垂直磁気記録媒体では、とくに、ＣｏＺｒ系非晶質軟磁性下地層と、ＣｏＣｒ系垂直記録層との間にごく薄く形成した網目構造層によりＣｏＣｒ系垂直記録層の結晶粒子を小さくすることができる。 In the perpendicular magnetic recording medium according to the present invention, in particular, the crystal grains of the CoCr-based perpendicular recording layer are made small by the network structure layer formed very thin between the CoZr-based amorphous soft magnetic underlayer and the CoCr-based perpendicular recording layer. can do.
図１は本発明に係る垂直磁気記録媒体を模式的に示した断面図、
図２は図１に示した網目構造層として種々の物質を挿入したときのＨｃ変化率及びＳ／Ｎ上昇量を示した図、
図３は図１に示した網目構造層への挿入物質の融点とＨｃ変化率との関係を示した図、
図４は図１に示した網目構造層への挿入物質の表面張力とＨｃ変化率との関係を示した図、
図５はＮｂの堆積高さとＨｃとの関係を示した図、
図６はＮｂの堆積高さとＳ／Ｎとの関係を示した図である。
FIG. 1 is a sectional view schematically showing a perpendicular magnetic recording medium according to the present invention.
FIG. 2 is a diagram showing the Hc change rate and S / N increase when various substances are inserted as the network structure layer shown in FIG.
FIG. 3 is a diagram showing the relationship between the melting point of the substance inserted into the network structure layer shown in FIG.
FIG. 4 is a diagram showing the relationship between the surface tension of the substance inserted into the network structure layer shown in FIG.
FIG. 5 is a diagram showing the relationship between the deposition height of Nb and Hc,
FIG. 6 is a graph showing the relationship between the deposition height of Nb and S / N.
図１に示した如く、本発明に係る垂直磁気記録媒体１０は、プラスチックフィルム，ガラス材などの非磁性材を用いた基板１１上に、硬磁性ピンニング層１２と、ＣｏＺｒ系非晶質軟磁性下地層１３と、網目構造層１４と、ＣｏＣｒ系垂直記録層１５と、保護層１６とがこの順で積層された状態で形成されている。この際、垂直磁気記録媒体１０中の各層１１〜１６は、全てマグネトロンスパッタ法により成膜されている。 As shown in FIG. 1, a perpendicular magnetic recording medium 10 according to the present invention includes a hard magnetic pinning layer 12 and a CoZr amorphous soft magnetic material on a substrate 11 made of a nonmagnetic material such as a plastic film or a glass material. The underlayer 13, the network structure layer 14, the CoCr-based perpendicular recording layer 15, and the protective layer 16 are formed in this order. At this time, all the layers 11 to 16 in the perpendicular magnetic recording medium 10 are formed by a magnetron sputtering method.
より具体的に成膜順に説明すると、まず、基板１１として例えば鏡面加工を施した円盤状のガラス基板を用いており、この基板１１上に硬磁性ピンニング層１２として、Ｃｏ８３Ｓｍ１７（ａｔ％）を略１５０ｎｍの厚さで成膜している。この硬磁性ピンニング層１２は、ＣｏＺｒ系非晶質軟磁性下地層１３の磁区をピンニングするものである。 More specifically, in order of film formation, first, for example, a disk-shaped glass substrate having a mirror finish is used as the substrate 11, and Co83Sm17 (at%) is abbreviated as a hard magnetic pinning layer 12 on the substrate 11. The film is formed with a thickness of 150 nm. The hard magnetic pinning layer 12 is for pinning the magnetic domains of the CoZr amorphous soft magnetic underlayer 13.
次に、硬磁性ピンニング層１２上にＣｏＺｒ系非晶質軟磁性下地層１３として、Ｃｏ８８Ｚｒ７Ｎｂ５（ａｔ％）膜を略３６０ｎｍの厚さで成膜している。 Next, a Co88Zr7Nb5 (at%) film having a thickness of approximately 360 nm is formed on the hard magnetic pinning layer 12 as a CoZr-based amorphous soft magnetic underlayer 13.
次に、ＣｏＺｒ系非晶質軟磁性下地層１３上に本発明の要部となる網目構造層１４をＣｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金（混合物）のうちのいずれかの物質を用いて網目状にごく薄く成膜している。 Then, either a network structure layer 14 as a main part of the present invention on the CoZr based amorphous soft magnetic underlayer 13 Cr, B, Nb, Mo , Ta, W, C 及 beauty of these alloys (mixture) These materials are used to form an extremely thin network.
ここで、一般的に、薄膜を形成する場合に、成膜対象物質が堆積する初期段階では島状構造をとり、成膜対象物質の堆積が進むと、隣り合う島状構造同士が結合しあって網目構造となる。更に成膜対象物質の堆積が進むと、網目の隙間が埋めつくされ、連続的な膜構造（または層構造）となる。一般的に薄膜（または薄膜層）と呼ばれるものは、この連続構造からなるものを指す。 Here, in general, when forming a thin film, an island-like structure is formed at the initial stage of deposition of a film formation target substance, and when the deposition target substance is deposited, adjacent island structures are joined together. And has a mesh structure. As the deposition target material further accumulates, the mesh gaps are filled, and a continuous film structure (or layer structure) is obtained. What is generally referred to as a thin film (or thin film layer) refers to one having this continuous structure.
そこで、本発明の要部となる網目構造層１４を成膜する場合に、上記したＣｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金（混合物）のうちのいずれかの物質を堆積させながら隣り合う島状構造同士が結合しあって網目構造となる段階で成膜を中止することで、網目構造層１４は島状構造と連続的膜構造との中間状態の網目構造を取ることになる。 Therefore, when forming a network structure layer 14 as a main part of the present invention, Cr was above, B, Nb, Mo, Ta, W, one of the substances of the C 及 beauty alloys (mixture) is deposited In this case, the network structure layer 14 takes a network structure in an intermediate state between the island structure and the continuous film structure by stopping the film formation when the adjacent island structures are combined to form a network structure. become.
この際、網目構造層１４中で網目構造が形成される条件は、後述するように成膜対象物質の融点や表面張力に強く依存し、融点が１７００°Ｃ〜３８００°Ｃ、表面張力γ０が１．５Ｎ／ｍ〜２．５Ｎ／ｍの物質を、平均堆積高さ０．５ｎｍ〜２．３ｎｍの範囲でごく薄く形成することにより網目構造が実現できること、網目構造を形成する物質としては上記したようにＣｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃおよびこれらの合金（混合物）が有効であることを本発明者らの研究により判明した。
At this time, the conditions under which the network structure is formed in the network structure layer 14 strongly depend on the melting point and surface tension of the film forming target material as described later, and the melting point is 1700 ° C. to 3800 ° C. and the
この後、網目構造層１４上にＣｏＣｒ系垂直記録層１５として、Ｃｏ７７．４Ｃｒ２０Ｔａ１．３Ｎｂ１．３（ａｔ％）を略５０ｎｍの厚さで成膜し、更に、ＣｏＣｒ系垂直記録層１５を保護するために、保護層１６としてカ−ボン膜を略５ｎｍの厚さで成膜している。 Thereafter, a Co77.4Cr20Ta1.3Nb1.3 (at%) film having a thickness of about 50 nm is formed on the network structure layer 14 as a CoCr-based perpendicular recording layer 15 to further protect the CoCr-based perpendicular recording layer 15. Therefore, a carbon film having a thickness of about 5 nm is formed as the protective layer 16.
上記のように、ＣｏＺｒ系非晶質軟磁性下地層１３と、ＣｏＣｒ系垂直記録層１５との間に網目構造層１４を、ＣｏＺｒ系非晶質軟磁性下地層１３中のＣｏと、ＣｏＣｒ系垂直記録層１５中のＣｏとが結合できるようにごく薄い厚さに形成すると、ＣｏＺｒ系非晶質軟磁性部分が露出した微細な多数の網目の隙間が、ＣｏＣｒ系垂直記録層１５が結晶成長する際の核となり、結晶粒子が大きく成長するのが抑制されるので、保磁力（Ｈｃ）が向上する。この時、網目の隙間を介してＣｏＺｒ系非晶質軟磁性下地層１３とＣｏＣｒ系垂直記録層１５とが直接結合し合うので、磁気的なスペーシングを増大させることがなく、また、ＣｏＣｒ系垂直記録層１５の垂直配向度を損ねることもないので、本発明に係る垂直磁気記録媒体１０を用いて情報信号を記録再生した時に、垂直磁気記録媒体１０の記録再生効率が高くなり、情報信号の再生出力も高くなる。また、媒体ノイズが小さく、高いＳ／Ｎ比得られる。更に、ＣｏＣｒ系垂直記録層１５が高い保磁力（Ｈｃ）を有することによって、記録信号の熱安定性が高くなる。 As described above, the network structure layer 14 is formed between the CoZr-based amorphous soft magnetic underlayer 13 and the CoCr-based perpendicular recording layer 15, and the Co in the CoZr-based amorphous soft magnetic underlayer 13 and the CoCr-based layer are formed. When formed in a very thin thickness so as to be able to bond with Co in the perpendicular recording layer 15, a large number of fine mesh gaps where the CoZr amorphous soft magnetic portion is exposed cause crystal growth of the CoCr perpendicular recording layer 15. As a result, the cohesive force (Hc) is improved. At this time, since the CoZr-based amorphous soft magnetic underlayer 13 and the CoCr-based perpendicular recording layer 15 are directly coupled to each other through the mesh gap, the magnetic spacing is not increased, and the CoCr-based recording is not caused. Since the perpendicular orientation of the perpendicular recording layer 15 is not impaired, when the information signal is recorded / reproduced by using the perpendicular magnetic recording medium 10 according to the present invention, the recording / reproduction efficiency of the perpendicular magnetic recording medium 10 becomes high, and the information signal Playback output also increases. Moreover, medium noise is small and a high S / N ratio can be obtained. Furthermore, since the CoCr type perpendicular recording layer 15 has a high coercive force (Hc), the thermal stability of the recording signal is increased.
ここで、ＣｏＣｒ系垂直記録層１５の保磁力（Ｈｃ）の測定はカ−効果を用い、垂直配向度はｃ軸分散角として、Ｘ線回折による（００２）面のロッキングカ−ブの半値幅Δθ５０で評価した。 Here, the coercive force (Hc) of the CoCr-based perpendicular recording layer 15 is measured using the Kerr effect, the vertical orientation degree is defined as the c-axis dispersion angle, and the half width of the rocking curve on the (002) plane by X-ray diffraction. Evaluation was performed at Δθ50.
また、垂直磁気記録媒体１０への記録再生は、ハードディスク装置に使用されるマージ型のＧＭＲヘッドを用いて行った。更に、Ｓ／Ｎ比の評価は、６００ｋｆｃｉの信号に対して行った。 Recording and reproduction on the perpendicular magnetic recording medium 10 was performed using a merge type GMR head used in a hard disk device. Further, the S / N ratio was evaluated for a signal of 600 kfci.
そして、網目構造層１４に用いる成膜対象物質を種々変えて、各種の物質を網目構造層１４としてごく薄く成膜した後に、上記の測定で得られた結果を図２に示した如くにまとめた。 Then, after variously changing the deposition target materials used for the network structure layer 14 and forming various materials as the network structure layer 14 very thinly, the results obtained by the above measurement are summarized as shown in FIG. It was.
この際、図２中において、Ｈｃ（０）は網目構造とすべき物質を挿入しない場合の保磁力であり、Ｈｃは網目構造とすべき物質を挿入した場合の保磁力であり、Ｈｃ変化率はＨｃをＨｃ（０）で規格化した値Ｈｃ／Ｈｃ（０）である。また、Ｓ／Ｎ上昇量も同様に、網目構造とすべき物質を挿入しない時のＳ／Ｎ比を０ｄＢとした場合の、挿入した時のＳ／Ｎ比である。 In this case, in FIG. 2, Hc (0) is a coercive force when a substance to be a network structure is not inserted, and Hc is a coercive force when a substance to be a network structure is inserted, and the Hc change rate. Is a value Hc / Hc (0) obtained by normalizing Hc with Hc (0). Similarly, the S / N increase amount is also the S / N ratio at the time of insertion when the S / N ratio at the time when the substance to be a network structure is not inserted is 0 dB.
図２から明らかなように、Ｈｃ変化率Ｈｃ／Ｈｃ（０）が１．０以上となった物質は、Ｃｒ，Ｗ，Ａｌ５０Ｎｉ５０，Ｃ，Ｍｏ，Ｔａ，Ｂ，Ｎｂ２６Ｂ７４（ａｔ％），Ｎｂ３３Ｂ６７（ａｔ％），Ｎｂ３７Ｂ６３（ａｔ％），Ｎｂ４６Ｂ５４（ａｔ％），Ｎｂ５０Ｂ５０（ａｔ％），Ｎｂであり、Ｈｃ変化率Ｈｃ／Ｈｃ（０）が１．０以上となったこれらの物質が網目構造層１４に適している。 As is clear from FIG. 2, the substances having Hc change rate Hc / Hc (0) of 1.0 or more are Cr, W, Al50Ni50, C, Mo, Ta, B, Nb26B74 (at%), Nb33B67 ( at%), Nb37B63 (at%), Nb46B54 (at%), Nb50B50 (at%), Nb, and these substances whose Hc change rate Hc / Hc (0) is 1.0 or more are network layers. 14 is suitable.
また、図３に示したように、網目構造層１４への挿入物質の融点とＨｃ変化率との関係からＨｃ変化率Ｈｃ／Ｈｃ（０）が１．０以上の物質は、上記した略同様に、ＡｌＮｉ，Ｃｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃであり、これらの物質の融点は１７００°Ｃから３８００°Ｃである。 In addition, as shown in FIG. 3, a substance having an Hc change rate Hc / Hc (0) of 1.0 or more is substantially the same as described above from the relationship between the melting point of the substance inserted into the network structure layer 14 and the Hc change rate. In addition, AlNi, Cr, B, Nb, Mo, Ta, W, and C, and these materials have melting points of 1700 ° C to 3800 ° C.
また、図４に示したように、網目構造層１４への挿入物質の表面張力γ０とＨｃ変化率との関係からＨｃ変化率Ｈｃ／Ｈｃ（０）が１．０以上の物質は、Ｃｒ，Ｎｂ，Ｍｏ，Ｔａ，Ｗであり、これらの物質の表面張力γ０は１．５から２．５の範囲である。 In addition, as shown in FIG. 4, from the relationship between the surface tension γ0 of the substance inserted into the network structure layer 14 and the Hc change rate, a substance having an Hc change rate Hc / Hc (0) of 1.0 or more is Cr, Nb, Mo, Ta, and W, and the surface tension γ0 of these materials is in the range of 1.5 to 2.5.
上記から網目構造層１４への挿入物質のＨｃ変化率が１．０以上となる条件は、挿入物質の融点と、挿入物質の表面張力γ０に強く依存していることがわかる。 From the above, it can be seen that the conditions under which the Hc change rate of the insertion material into the network structure layer 14 is 1.0 or more strongly depend on the melting point of the insertion material and the surface tension γ0 of the insertion material.
そして、網目構造層１４への挿入物質のＨｃ変化率が１．０以上の物質をごく薄く成膜した後に、ＣｏＣｒ系垂直記録層１５に対してＸ線回折装置を用いてｃ軸分散角Δθ５０｛（００２）｝面のロッキングカ−ブの半値幅を測定したところ、いずれも４°以下と小さく、垂直配向度の高いものであった。
Then, after forming a very thin material having an Hc change rate of 1.0 or more of the insertion material into the network structure layer 14, the c-axis
また、ＣｏＣｒ系垂直記録層１５の平均粒子径を、透過型電子顕微鏡（ＴＥＭ）で調べたところ、網目構造層１４を形成しない場合に約３５ｎｍであったのに対し、上記したように挿入物質のＨｃ変化率が１．０以上の物質を網目構造層１４としてごく薄く成膜した場合に約２０ｎｍと小さくなっていた。従って、網目構造層１４によりＣｏＣｒ系垂直記録層１５の結晶粒子を小さくできることが判明した。これは、ＣｏＺｒ系非晶質軟磁性部分が露出した微細な多数の網目の隙間が、ＣｏＣｒ系垂直記録層１５が結晶成長する際の核となり、結晶粒が大きく成長するのが抑制され、微粒子化したためである。 Further, when the average particle diameter of the CoCr-based perpendicular recording layer 15 was examined with a transmission electron microscope (TEM), it was about 35 nm when the network structure layer 14 was not formed. In the case where a material having a Hc change rate of 1.0 or more was formed very thin as the network structure layer 14, it was as small as about 20 nm. Therefore, it has been found that the crystal structure layer 14 can reduce the crystal grains of the CoCr-based perpendicular recording layer 15. This is because a large number of fine mesh gaps in which the CoZr-based amorphous soft magnetic portion is exposed serve as a nucleus when the CoCr-based perpendicular recording layer 15 grows crystals, so that large growth of crystal grains is suppressed. This is because
更に、ＣｏＺｒ系非晶質軟磁性下地層１３と、ＣｏＣｒ系垂直記録層１５との間に網目構造層１４をごく薄く形成した垂直磁気記録媒体１０に対して、ハードディスク装置に使用されるマージ型のＧＭＲヘッドを用いて、６００ｋｆｃｉの信号に対してＳ／Ｎ比の評価を行ったところ、上記条件の範囲においてはいずれもＳ／Ｎ上昇量は正の値をとり、Ｓ／Ｎ比が向上した。これはＣｏＣｒ系垂直記録層１５が微粒子化したために媒体ノイズＮが低減し、且つ、網目の隙間を介してＣｏＺｒ系非晶質軟磁性下地層１３とＣｏＣｒ系垂直記録層１５とが直接結合しているので、磁気的なスペーシングを増大させることがなく、また、ＣｏＣｒ系垂直記録層１５の垂直配向度を損なっていないので、記録再生効率が高く再生信号が大きいためである。 Further, a merge type used in a hard disk device is used for the perpendicular magnetic recording medium 10 in which the network structure layer 14 is formed very thin between the CoZr-based amorphous soft magnetic underlayer 13 and the CoCr-based perpendicular recording layer 15. When the S / N ratio was evaluated for a 600 kfci signal using the GMR head, the S / N increase amount was positive and the S / N ratio was improved within the range of the above conditions. did. This is because the medium noise N is reduced because the CoCr-based perpendicular recording layer 15 has been made fine, and the CoZr-based amorphous soft magnetic underlayer 13 and the CoCr-based perpendicular recording layer 15 are directly coupled via the mesh gap. since it is, without increasing the magnetic spacing, also because it does not impair the vertical orientation of the CoCr-based perpendicular recording layer 15, because there is a large high reproduced signal recording and reproducing efficiency.
次に、網目構造層１４への挿入物質の平均堆積高さは、０．５ｎｍ〜２．３ｎｍの範囲が特に有効であり、この範囲内で網目構造をとると磁気記録特性が良好に得られる。ここで、平均堆積高さとは、ある面積に対して堆積した量（体積）をその面積で割った値である。具体的な例として、図５，図６にはそれぞれ、Ｎｂを例にとった場合の、Ｈｃと、Ｓ／Ｎとの平均堆積高さ依存性を示している。この例では、網目構造層１４中のＮｂの平均堆積高さが０．５ｎｍ〜２．３ｎｍの範囲でＨｃとＳ／Ｎ比のどちらにも改善が見られ、有効に作用していることがわかる。尚、ここでの図示を省略するものの、網目構造層１４にＮｂ以外で上記したＣｒ，Ｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金（混合物）のうちのいずれかの物質を挿入しても０．５ｎｍ〜２．３ｎｍの範囲で特に有効であることが実験により得られた。 Next, the average deposition height of the intercalation material in the network structure layer 14 is particularly effective in the range of 0.5 nm to 2.3 nm. If the network structure is taken within this range, good magnetic recording characteristics can be obtained. . Here, the average deposition height is a value obtained by dividing the amount (volume) deposited for a certain area by the area. As a specific example, FIGS. 5 and 6 show the dependence of Hc and S / N on the average deposition height when Nb is taken as an example. In this example, when the average deposition height of Nb in the network structure layer 14 is in the range of 0.5 nm to 2.3 nm, both the Hc and S / N ratios are improved, and the Nb is acting effectively. Recognize. Incidentally, although not shown here, Cr in a mesh structure layer 14 and the outside Nb, B, Mo, Ta, W, be inserted to any substance of C 及 beauty alloys (mixture) Experiments have shown that it is particularly effective in the range of 0.5 nm to 2.3 nm.
１０…本発明に係る垂直磁気記録媒体、
１１…基板、１２…硬磁性ピンニング層、１３…ＣｏＺｒ系非晶質軟磁性下地層、
１４…網目構造層、１５…ＣｏＣｒ系垂直記録層、１６…保護層。
10: Perpendicular magnetic recording medium according to the present invention,
11 ... Substrate, 12 ... Hard magnetic pinning layer, 13 ... CoZr-based amorphous soft magnetic underlayer,
14 ... network structure layer, 15 ... CoCr type perpendicular recording layer, 16 ... protective layer.
Claims (1)
前記ＣｏＺｒ系非晶質軟磁性下地層と、前記ＣｏＣｒ系垂直記録層との間に網目構造層を形成し、
前記網目構造層は、Ｃｒ，Ｂ，Ｎｂ，Ｍｏ，Ｔａ，Ｗ，Ｃ及びこれらの合金材料のうちのいずれかの物質からなり、厚さが０．５〜２．３ｎｍであることを特徴とする垂直磁気記録媒体。 In a perpendicular magnetic recording medium in which a CoZr-based amorphous soft magnetic underlayer and a CoCr-based perpendicular recording layer are sequentially laminated on a substrate ,
Said CoZr based amorphous soft magnetic underlayer, and forming a network structure layer between the CoCr-based perpendicular recording layer,
The network structure layer is made of any one of Cr, B, Nb, Mo, Ta, W, C, and alloy materials thereof, and has a thickness of 0.5 to 2.3 nm. Perpendicular magnetic recording medium.
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