JP3796256B2 - Magnetic recording / reproducing device - Google Patents

Description

  The present invention detects a magnetic recording medium (discrete type magnetic recording medium) having a so-called servo area and an information data area, on which a magnetic recording layer is formed in a predetermined uneven pattern on a substrate, and a servo signal of this magnetic recording medium In addition, the present invention relates to a magnetic recording / reproducing apparatus having a magnetic head for recording / reproducing information data.

  Conventionally, the improvement in the surface recording density of a magnetic recording medium such as a hard disk has been achieved by both (1) improving the linear recording density and (2) improving the track density. In order to further increase the density in the future, it is necessary to improve the recording density based on both of the above methods.

  With regard to improving the track density, problems such as side fringing and crosstalk due to the processing limit of the magnetic head, the spread of the magnetic head magnetic field, and the like have become obvious. It can be said that the improvement of the surface recording density by advancing the track technology has reached the limit.

  On the other hand, as a method for improving the linear recording density, the conventional longitudinal magnetic medium has been made thin and high coercive force, but from the viewpoint of further increasing the density of the medium and the stability against thermal fluctuation of the recording magnetization. Attention has been focused on perpendicular magnetic recording media that satisfy these conditions.

  Under such circumstances, a discrete track disk type magnetic recording medium in which a recording layer is formed in a predetermined concavo-convex pattern has been proposed as a technique for improving the surface recording density and complementing the increase in the track density of the magnetic head. Yes. For example, Japanese Patent Application Laid-Open No. 11-328662 discloses a magnetic recording medium in which predetermined irregularities are provided in advance on a substrate, and a single perpendicular magnetic recording layer is formed along the irregularities.

  To achieve high recording density, low spacing is necessary. However, the uneven shape of the recording layer may not provide stable flying characteristics of the magnetic head, and may cause problems such as head crashes. From this point of view, Japanese Patent Application Laid-Open No. 10-222944 discloses a recording medium for changing the uneven shape in the track width direction for the purpose of floating stability of the magnetic head.

  Further, JP 2000-195042 A proposes a discrete type magnetic recording medium in which concave and convex portions are filled with a nonmagnetic material or other material in order to ensure the stability of the flying characteristics of the magnetic head. Yes.

  Japanese Laid-Open Patent Publication No. 6-111502 discloses a technique that defines the relationship between the width of a tracking servo burst pattern, the track pitch, and the read-out width of a reproducing head using a rectangular uneven structure in a longitudinal recording medium. .

  In general, in a magnetic disk device, a servo area for tracking a magnetic head is recorded on a magnetic recording medium used by a servo track writer.

  The servo area generally includes an ISG (Initial Signal Gain) part, an SVAM (SerVo Address Mark) part, a Gray code part, a burst part, and a pad part, and these are various in order to perform a predetermined function. The magnetic pattern is formed.

  In these magnetic patterns, the burst portion is recorded with a width of one track in the radial direction of the magnetic recording medium. The other ISG, SVAM, gray code, and pad sections are recorded continuously in the radial direction of the disk, or are recorded continuously over at least several tracks in the radial direction. .

  By the way, in recent years, the recording density of the magnetic recording apparatus has increased remarkably, and the size of the recording bits recorded on the magnetic recording medium has also decreased as the recording density increased. For this reason, it is necessary to reduce the size of the magnetic particles in order to ensure a high S / N. In the medium of the longitudinal recording system that has been widely used in the past, the magnetization energy KuV (Ku: magnetic anisotropy constant, V: magnetism). If the value of KuV / kT, which is the ratio between the volume of the particles) and the thermal energy kT of the ambient temperature (k: Boltzmann constant, T: absolute temperature) is less than about 60 as a general guideline, heat as disturbance It is said that a phenomenon of so-called thermal fluctuation, in which magnetization is stochastically fluctuated due to energy disturbance, and magnetization is lowered with time, becomes apparent.

  Therefore, in order to increase the magnetization energy of the magnetic particles, a perpendicular magnetic recording medium that can increase the thickness of the medium even at high density has attracted attention.

  In perpendicular magnetic recording media, the higher the density, the more stable the magnetization and the greater the resistance to thermal fluctuations.On the other hand, the low recording density, that is, the demagnetizing field that reduces the magnitude of magnetization in the region where the bit length is large increases. The effect of this is accelerated and the recorded magnetization tends to decrease.

  Therefore, the area most affected by the thermal fluctuation is a servo area where a servo signal having a relatively low recording density is recorded.

  Once the servo signal is recorded, it is not normally re-recorded by the magnetic head, so it is easily affected by thermal fluctuations over a long period of time. This may cause a problem that the signal quality of the signal deteriorates.

  In order to deal with such a problem, Japanese Patent Application Laid-Open No. 11-25402 discloses the maximum demagnetization field at the time of magnetization saturation in a recording bit in the recording magnetization of a tracking servo signal of a perpendicular magnetic recording medium having no concavo-convex structure. A technique for setting the bit length of the servo signal so as to be smaller than the coercive force of the layer is disclosed, and a relational expression for setting is required.

  In this proposed technique, the servo signal is continuously arranged while the perpendicular magnetization M of the rectangular bits are alternately reversed as shown in the drawing of the publication, so that the demagnetizing field Hd generated in a certain bit is also the closest. The demagnetizing field is reduced by the magnetic field H from the bit. In particular, at the boundary between bits, the demagnetizing field is theoretically zero, and it is considered that a value close to saturation magnetization is secured in the vicinity of an ideal magnetization transition.

  However, in the case of a discrete track disk provided with a concavo-convex structure, as shown in Japanese Patent Laid-Open No. 6-111502, in a burst portion in the concavo-convex shape of a magnetic recording layer corresponding to a servo pattern, a bit for rectangular recording is usually used. Are arranged at intervals of 1 bit. In the ISG portion, SVAM portion, and gray code portion, rectangular bits that are long in the disk radial direction are arranged at intervals of one bit.

  In the discrete track disk in which the magnetic recording layer is processed to have a concavo-convex structure as described above, unlike the method of recording continuously reversing magnetization on a perpendicular magnetic medium as shown in Japanese Patent Laid-Open No. 11-25402, servo signal recording is performed. The convex magnetic recording layer thus formed is completely isolated, and there is no nearest neighbor bit (reversed magnetization) that originally acts to weaken the demagnetizing field. Further, the bits located at a position 1 bit far away are magnetized in the same magnetization direction, and the effect of reducing the demagnetizing field can hardly be expected, but rather acts to increase the demagnetizing field.

  Therefore, a design guideline for the magnetic recording layer of the servo signal convex portion formed completely isolated is desired.

  By the way, when forming the concavo-convex structure of the perpendicular magnetic recording layer (magnetic layer), the working time can be shortened and the manufacturing cost can be reduced as the depth of the concave portion is reduced. Therefore, the form in which the uneven magnetic layer is formed without completely removing the magnetic layer and the recess is filled with the nonmagnetic material is desirable from the viewpoint of simplifying the process and reducing the operation cost. I can say that.

  However, if the concave / convex shape of the magnetic layer is determined without taking any measures into consideration, problems such as a decrease in servo signal output with respect to the depth of the concave portion of the magnetic layer may occur. In particular, various deterioration modes may occur depending on the parameters of the concavo-convex structure of the perpendicular magnetic recording layer (magnetic layer) in the servo region, the depth of the recessed portion, and the magnetic characteristics of the perpendicular magnetic recording layer (magnetic layer) applied here. There is sex. For this reason, it is difficult to use a servo tracking signal in the convex portion of the magnetic layer formed in the concave / convex pattern while ensuring sufficient long-term reliability against thermal fluctuation.

Japanese Patent Laid-Open No. 11-328662 JP-A-10-222944 JP 2000-195042 A JP-A-6-111502

  The present invention has been devised based on such a situation, and the object is to use a magnetic recording medium using a perpendicular magnetic recording medium having a servo tracking signal at a convex portion of a magnetic layer formed by a concave-convex pattern. An object of the present invention is to provide a magnetic recording apparatus having a magnetic recording medium capable of suppressing the deterioration of servo signals caused by thermal fluctuation and ensuring a stable servo function over a long period of time.

  In order to solve such problems, the magnetic recording / reproducing apparatus of the present invention has a discrete type perpendicular magnetic recording medium having a data information recording section and a tracking servo information section, and the influence of thermal fluctuation of the medium. In the servo area of the perpendicular magnetic recording medium that receives the strongest magnetic field, the rugged structure of the servo area should be set in consideration of the magnetic characteristics so that the influence of the demagnetizing field that accelerates the thermal fluctuation of the perpendicular magnetic recording medium can be reduced. is there. In particular, for the concavo-convex structure necessary for each function of the servo area, in order to overcome the demagnetizing field that accelerates thermal fluctuation, the configuration specifications and magnetic characteristic specifications of the concavo-convex magnetic layer of the perpendicular magnetic recording medium are set. .

また、本発明の磁気記録再生装置において、前記凸部からなる垂直磁気記録層の垂直方向の保磁力をＨｃ、残留磁化をＭｒ、保磁力角型比をＳ^*としたとき、前記保磁力角型比Ｓ^*が０．８以上の値をとり、しかも下記式（２）の関係を満たすようにバースト部の仕様が設定される。

また、本発明の磁気記録再生装置において、前記凸部からなる垂直磁気記録層に対応する下辺であるＬ２と、前記垂直磁気記録層の間隙であるＬ３との和をサーボ信号の周波数の波長として設定するように構成される。
また、本発明は、データ情報記録部及びトラッキング用のサーボ用情報部を有する垂直磁気記録媒体と、前記サーボ用情報部のサーボ情報を検出するとともに、前記データ情報記録部へデータ情報を記録し再生する磁気ヘッドを有する磁気記録再生装置であって、前記サーボ用情報部は、所定の凹凸パターンで形成された垂直磁気記録層のうちの凸パターンで構成されるとともに、凹部パターンの内部は非磁性材料で充填されており、該サーボ用情報部は、ＩＳＧ部、ＳＶＡＭ部、グレイコード部、パッド部を形成するためのトラック半径方向（トラック幅方向）に伸びる帯状凸部を有し、前記帯状凸部は、トラック円周方向に、凸部からなる垂直磁気記録層の表面に対応する上辺Ｌ１、凸部からなる垂直磁気記録層の基部到達に至るまで延長された底辺に対応する下辺（第２の台形形状を延長した凸部からなる垂直磁気記録層の底辺に対応する下辺）Ｌ２（ただし、Ｌ２＞Ｌ１）の台形形状を有するとともに、トラック半径方向にはＬ２の長さの１００倍以上の長さを備える帯状形状となっており、前記帯状凸部の隣接する下辺Ｌ２の間の間隙長さをＬ３とし、凸部の領域の垂直磁気記録層の全体厚さ（凸部の垂直磁気記録層の上辺から下辺までの距離）をｔとし、凹部の下に残存している垂直磁気記録層の厚さをδとし、前記帯状凸部の垂直磁気記録層の膜面に垂直方向の保磁力をＨｃ、飽和磁化をＭｓ、保磁力角型比をＳ^*としたとき、前記保磁力角型比Ｓ^*が０．８以上の値をとり、しかも下記式（３）の関係を満たすように帯状凸部の仕様が設定されてなるように構成される。

また、本発明の磁気記録再生装置において、前記帯状凸部の垂直磁気記録層の膜面に垂直方向の保磁力をＨｃ、残留磁化をＭｒ、保磁力角型比をＳ^*としたとき、前記保磁力角型比Ｓ^*が０．８以上の値をとり、しかも下記式（４）の関係を満たすように帯状凸部の仕様が設定される。

また、本発明の磁気記録再生装置において、前記凸部からなる垂直磁気記録層に対応する下辺であるＬ２と、前記凸部からなる垂直磁気記録層の間隙であるＬ３との和をサーボ信号の周波数の波長として設定するように構成される。
また、本発明の磁気記録再生装置において、前記サーボ用情報部におけるサーボ信号のための記録は、前記垂直磁気記録媒体を直流磁界中で前記垂直磁気記録層に垂直に印加することにより、一括磁化されてなるように構成される。
また、本発明の磁気記録再生装置において、前記サーボ用情報部は所定の凹凸パターンで形成されており、凹部にはディスクリート作用を発揮させるための非磁性材料が充填されてなるように構成される。 That is, the present invention detects a servo information of a perpendicular magnetic recording medium having a data information recording section and a tracking servo information section, and the servo information section, and records data information in the data information recording section. A magnetic recording / reproducing apparatus having a magnetic head for reproducing, wherein the servo information portion is constituted by a convex pattern of a perpendicular magnetic recording layer formed by a predetermined concavo-convex pattern, and the inside of the concave pattern is not The servo information section is filled with a magnetic material, and the servo information section includes a burst section in which a tracking burst signal is recorded. The burst section is a perpendicular magnetic recording layer composed of a plurality of convex sections in which the burst signal is recorded. the is formed by a predetermined arrangement, the perpendicular magnetic recording layer composed of the convex portion, the track width direction (track radius direction) and track Circumferentially, each having a first trapezoidal shape and a second trapezoidal shape, in the first trapezoidal shape of the track width direction, the upper side corresponding to the surface of the perpendicular magnetic recording layer composed of a convex portion W1, The lower side corresponding to the base extended to reach the base of the perpendicular magnetic recording layer comprising the convex portion (the lower side corresponding to the bottom of the perpendicular magnetic recording layer comprising the convex portion extending the first trapezoidal shape) is represented by W2 (however, W2> W1) , the gap length between the adjacent lower sides W2 is W3, and the upper side corresponding to the surface of the perpendicular magnetic recording layer made of the convex portion is L1 in the second trapezoidal shape in the track circumferential direction. The lower side corresponding to the base extended to reach the base of the perpendicular magnetic recording layer made of the convex portion ( the lower side corresponding to the base of the perpendicular magnetic recording layer made of the convex extending the second trapezoidal shape) is denoted by L2 ( However, L2> L1), Contacting a gap length between the lower side L2 and L3, the overall thickness of the perpendicular magnetic recording layer in the region of the protrusion (the distance from the upper side of the perpendicular magnetic recording layer of the convex portion to the lower side) and t, under the recess The thickness of the remaining perpendicular magnetic recording layer is δ, the coercive force in the direction perpendicular to the film surface of the perpendicular perpendicular magnetic recording layer is Hc, the saturation magnetization is Ms, and the coercive force squareness ratio is S ^* . In this case, the coercive force squareness ratio S ^* has a value of 0.8 or more, and the specifications of the burst portion are set so as to satisfy the relationship of the following formula (1).

Further, in the magnetic recording / reproducing apparatus of the present invention, when the coercive force in the perpendicular direction of the perpendicular magnetic recording layer composed of the convex portions is Hc, the residual magnetization is Mr, and the coercive force squareness ratio is S ^* , the coercive force angle is set. The specifications of the burst part are set so that the mold ratio S ^* takes a value of 0.8 or more and satisfies the relationship of the following formula (2).

In the magnetic recording / reproducing apparatus of the present invention, the sum of L2 which is the lower side corresponding to the perpendicular magnetic recording layer comprising the convex portions and L3 which is the gap between the perpendicular magnetic recording layers is used as the wavelength of the servo signal frequency. Configured to set.
The present invention also provides a perpendicular magnetic recording medium having a data information recording unit and a tracking servo information unit, and detects servo information in the servo information unit and records data information in the data information recording unit. A magnetic recording / reproducing apparatus having a magnetic head for reproducing, wherein the servo information portion is constituted by a convex pattern of a perpendicular magnetic recording layer formed by a predetermined concavo-convex pattern, and the inside of the concave pattern is not The servo information portion is filled with a magnetic material, and the servo information portion has an ISG portion, an SVAM portion, a gray code portion, and a belt-like convex portion extending in a track radial direction (track width direction) for forming a pad portion , The band-shaped convex portion extends in the track circumferential direction until the upper side L1 corresponding to the surface of the perpendicular magnetic recording layer made of the convex portion reaches the base of the perpendicular magnetic recording layer made of the convex portion. A lower side corresponding to the elongated bottom side (a lower side corresponding to the bottom side of the perpendicular magnetic recording layer formed of a convex portion extending from the second trapezoidal shape) L2 (where L2> L1) and a trapezoidal shape, and a track radial direction Has a belt-like shape having a length of 100 times or more of the length of L2, and the gap length between the adjacent lower sides L2 of the belt-like convex portion is L3, and the perpendicular magnetic recording layer in the region of the convex portion The total thickness (distance from the upper side to the lower side of the perpendicular magnetic recording layer of the convex portion) is t, and the thickness of the perpendicular magnetic recording layer remaining under the concave portion is δ, and the perpendicular magnetic property of the belt-like convex portion is When the coercivity in the direction perpendicular to the film surface of the recording layer is Hc, the saturation magnetization is Ms, and the coercivity squareness ratio is S ^* , the coercivity squareness ratio S ^* takes a value of 0.8 or more. It is configured so that the specifications of the belt- like convex part are set so as to satisfy the relationship of the following formula (3). The

In the magnetic recording / reproducing apparatus of the present invention, when the coercivity in the direction perpendicular to the film surface of the perpendicular magnetic recording layer of the belt-like convex portion is Hc, the residual magnetization is Mr, and the coercive force squareness ratio is S ^* , The specifications of the belt-like convex portions are set so that the coercive force squareness ratio S ^* takes a value of 0.8 or more and satisfies the relationship of the following formula (4).

In the magnetic recording / reproducing apparatus of the present invention, the sum of L2 that is the lower side corresponding to the perpendicular magnetic recording layer made of the convex portion and L3 that is the gap between the perpendicular magnetic recording layer made of the convex portion is the servo signal. It is configured to set as a frequency wavelength.
In the magnetic recording / reproducing apparatus of the present invention, recording for the servo signal in the servo information section is performed by applying the perpendicular magnetic recording medium perpendicularly to the perpendicular magnetic recording layer in a DC magnetic field, thereby performing collective magnetization. It is configured to be made.
In the magnetic recording / reproducing apparatus of the present invention, the servo information section is formed in a predetermined uneven pattern, and the recess is filled with a nonmagnetic material for exerting a discrete action. .

  The magnetic recording apparatus of the present invention overcomes the demagnetizing field that accelerates the thermal fluctuation against the concavo-convex structure necessary for each function of the servo area in the servo area of the perpendicular magnetic recording medium that is most affected by the thermal fluctuation of the medium. Therefore, since the configuration specifications and magnetic characteristics specifications of the concavo-convex magnetic layer of the perpendicular magnetic recording medium are set, the deterioration of the servo signal caused by the thermal fluctuation of the magnetization of the perpendicular magnetic recording layer of the concavo-convex structure in the servo area is suppressed. Thus, a stable servo function can be ensured over a long period of time.

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The magnetic recording / reproducing apparatus of the present invention detects a servo information of a magnetic information medium having a data information recording part and a servo information part for tracking, and a servo information part, and records data information in the data information recording part. And a magnetic head for reproduction.

  First, in order to grasp the overall configuration of the apparatus, a description will be given of a schematic configuration example of the magnetic recording / reproducing apparatus with reference to FIG.

(Description of schematic configuration example of magnetic recording / reproducing apparatus)
FIG. 6 shows a schematic configuration perspective view of a magnetic recording / reproducing apparatus which is a preferred example of the present invention.

  In this figure, a disk-shaped perpendicular magnetic recording medium is used as the magnetic recording medium 1, and this medium is driven to rotate by a spindle motor 2.

  Further, in order to read / write data from / to the magnetic recording medium, a recording / reproducing magnetic head 5 is provided at the tip of the rotating arm 4 extending from the outer side of the medium toward the inner side of the medium. It has been. The rotating arm 4 is rotated by a voice coil motor 3, and for example, the magnetic head can be positioned on a predetermined track based on a servo signal detected by a recording / reproducing magnetic head. .

  The recording / reproducing magnetic head 5 has a recording element and a reproducing element. For the recording element, for example, a main magnetic pole excitation type single magnetic pole head is used, and for the reproducing element, for example, a GMR (giant magnetoresistive effect) head is used. It is done. Instead of the GMR head, a TMR (tunneling magnetoresistive effect) head or the like may be used.

(Description of magnetic recording medium)
Next, the configuration of the magnetic recording medium will be described.

  FIG. 1 is a schematic plan view showing the overall shape of a disk-shaped magnetic recording medium 1 used in the present invention, and FIG. 2 is a partially enlarged schematic view of a minute portion 100 surrounded by a square in FIG. Indicated. In FIG. 2, a servo information section 90, which is an area where servo signals are recorded, and a data information recording section 80, which is a data track group for recording / reproduction, are mainly shown conceptually.

  FIG. 3 is a sectional view conceptually showing a preferred embodiment of the magnetic recording medium in the present invention, and FIG. 3 substantially corresponds to the sectional view taken along the line α-α in FIG.

  In FIG. 1, although not shown, a plurality of data track groups for recording and reproduction are concentrically arranged and formed on a disk substrate.

  Also, servo signal areas (servo information section 90: portions drawn in a radial pattern in the drawing) are formed radially outward from the center of the disk. That is, a so-called sector servo system in which the disk surface is divided into sectors is applied. Servo information is recorded in the servo information section 90 of the magnetic recording medium by a servo tracking writer.

  The structure of the servo information section 90 will be described in detail. The servo information section 90 (so-called servo area) includes an ISG section 91, an SVAM section 92, a gray code section 93, a burst section 94, and a pad section as shown in FIG. 95.

  An ISG (Initial Signal Gain) unit 91 is a continuous pattern provided to eliminate the influence of uneven magnetic characteristics of the magnetic film (magnetic layer) of the magnetic recording medium and the flying height of the magnetic head, and is continuous in the track radial direction. Is formed. While the ISG unit 91 is being reproduced by the magnetic head, the servo demodulation circuit determines the gain by auto gain control (AGC) in order to correct the output variation due to the magnetic recording medium and the magnetic head. The auto gain control (AGC) performing such an operation is turned OFF when the SVAM (SerVo Address Mark) unit 92 existing in the servo area is detected, and the reproduction amplitude existing in the subsequent burst unit 94 is set to the ISG unit 91. Normalize with the amplitude of.

  In the gray code portion 93, track number information and sector number information are recorded.

  The burst unit 94 is a pattern for obtaining accurate position information for accurately tracking the magnetic head to the track position. This pattern is usually composed of a set of first bursts 94a and second bursts 94b provided so as to equally straddle center lines that regulate adjacent track pitches, and positions shifted from these sets by a half track pitch. The third burst 94c and the fourth burst 94d existing in FIG. The burst portion 94 is normally recorded with a width of one track in the radial direction of the magnetic recording medium as shown in FIG.

  The pad unit 95 is a pattern provided to absorb the delay of the demodulation circuit so that the clock generation can be maintained while the servo demodulation circuit reproduces the servo area.

  The ISG portion 91, the SVAM portion 92, and the pad portion 95 are continuously recorded in the disc radial direction. The gray code portion 93 is also recorded over at least several tracks in the radial direction.

  Next, a preferred cross-sectional configuration example of the magnetic recording medium will be described with reference to FIG. 3 can be grasped as, for example, an α-α cross-sectional arrow view of FIG.

  As shown in FIG. 3, the magnetic recording medium includes a substrate 15, an alignment layer 14 formed on the substrate 15, a soft magnetic layer 11 formed on the alignment layer 14, and the soft magnetic layer. 11, an intermediate layer 12 formed on the intermediate layer 12, a perpendicular magnetic recording layer 10 corresponding to the concavo-convex convex portion formed on the intermediate layer 12, and a nonmagnetic layer 20 corresponding to the concave portion, and on these And a protective layer 13 to be formed. When forming the concavo-convex pattern in the formation of the perpendicular magnetic recording layer 10 of the present invention, the magnetic layer is not completely removed, and the magnetic layer remains about δ under the recess (residual magnetic layer 10a).

  That is, the servo information section in the present invention is constituted by a convex pattern (perpendicular magnetic recording layer 10) of magnetic layers formed by a predetermined concave and convex pattern, and the concave pattern is filled with a nonmagnetic material. ing.

  The ratio (δ / t) of the thickness δ of the magnetic layer 10a remaining under the concave portion to the thickness t of the perpendicular magnetic recording layer 10 corresponding to the magnetic layer of the convex portion (δ / t) is 0.6 or less, particularly 0.1 to 0. .6, more preferably 0.2 to 0.4. If this value exceeds 0.6 (the groove becomes shallow), the magnetization is easily recorded in the concave portion by the magnetic field from the recording head, and the unnecessary magnetic field becomes stronger from the recorded magnetization, and the noise component becomes large. Become. Also, if this value is less than 0.1 (the groove becomes deeper), it becomes difficult to perform predetermined accurate etching, and it is extremely difficult to flatten by filling with a nonmagnetic material after the groove is formed. It becomes difficult and stable production becomes difficult.

  As the substrate 15, a glass substrate, a NiP-coated aluminum alloy substrate, a Si substrate, or the like is preferably used. As the alignment layer 14, for example, an antiferromagnetic material such as PtMn for applying a magnetic anisotropic magnetic field in the track width direction of the soft magnetic layer 11 can be used. In addition, a nonmagnetic alloy for controlling the orientation may be used.

  Examples of the soft magnetic layer 11 include a CoZrNb alloy, an Fe-based alloy, a Co-based amorphous alloy, a soft magnetic / nonmagnetic multilayer film, and soft magnetic ferrite.

  The intermediate layer 12 is provided in order to control the perpendicular magnetic anisotropy and crystal grain size of the perpendicular magnetic recording layer formed on the intermediate layer. For example, a CoTi nonmagnetic alloy, Ru or the like is used. In addition, a nonmagnetic metal, an alloy, or an alloy having a low magnetic permeability that functions similarly may be used.

As the convex perpendicular magnetic recording layer 10 (residual magnetic layer 10a), a medium in which ferromagnetic particles such as CoPt are contained in a matrix in a SiO ₂ oxide material, a CoCr alloy, a FePt alloy, A Co / Pd-based artificial lattice type multilayer alloy or the like is preferably used.

As the material of the nonmagnetic layer 20 in the recess, nonmagnetic oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ and ferrite, nitrides such as AlN, and carbides such as SiC are used.

  A protective layer 13 such as a carbon thin film is usually formed on the surface of the convex perpendicular magnetic recording layer 10 or the nonmagnetic layer 20 filled in the concave portion using a CVD method or the like.

Formation of the perpendicular magnetic recording layer 10 and the nonmagnetic layer 20 based on the concavo-convex pattern (formation of a so-called discrete type medium) is performed after, for example, etching the perpendicular magnetic recording layer 10 formed to a predetermined thickness into a predetermined concavo-convex shape. Then, SiO ₂ corresponding to the etching depth is sputtered to fill the etched recess. Thereafter, the SiO ₂ deposited excessively on the perpendicular magnetic recording layer 10 may be removed by an oblique ion beam etching method or the like while the medium is rotated to flatten the entire surface of the medium.

(Specification settings for servo area (servo information section))
The main part of the present invention is that the servo signal is deteriorated in a servo area (servo information part) composed of a convex pattern in a magnetic layer (so-called digging type magnetic layer) formed with a predetermined uneven pattern. It can be said that the configuration specifications and magnetic characteristics specifications of the concavo-convex magnetic layer of the perpendicular magnetic recording medium are set so that the servo function can be ensured over a long period of time.

  Hereinafter, regarding the magnetic recording layer (magnetic layer) having a convex structure for each function in the servo area, (1) the relationship between the length in the track radial direction (disk radial direction) and the length in the track circumferential direction is considered. The burst group 94 (94a to 94d) which is the first group that needs to be performed, and (2) the length in the track radial direction (disk radial direction) is extremely longer than the length in the track circumferential direction. As a second group, the ISG unit 91, the SVAM unit 92, the gray code unit 93, and the pad unit 95 need only be considered in the track circumferential direction.

(1) Description of the first group The convex shape that satisfies the requirements of the first group corresponds to the shape of the burst portion 94 as described above. As shown in the schematic perspective view of FIG. 4, the burst portion 94 is formed by arranging a perpendicular magnetic recording layer (magnetic layer) 10 composed of a plurality of convex portions in which the magnetization of the burst signal is recorded in the same direction. The perpendicular magnetic recording layer 10 composed of convex portions has a substantially first trapezoidal shape and a second trapezoidal shape in the track width direction and the track circumferential direction, respectively (square pyramid shape). .

  In the present invention, the residual magnetic layer 10a remains under the recess. The significance of leaving the residual magnetic layer 10a under the recess is because of the shortening of the recess processing step and the ease of subsequent flattening by reducing the recess depth. However, the signal from the magnetic layer under the recess must be deep enough not to affect the servo area and the data area.

  In order to facilitate understanding of the form of the perpendicular magnetic recording layer 10 composed of convex portions, the description of the nonmagnetic layer filled in the concave portions is omitted in the drawing.

  In the first trapezoidal shape in the track width direction (track radial direction) that can be seen in the front of the drawing in FIG. 4, the upper side corresponding to the surface of the perpendicular magnetic recording layer (magnetic layer) 10 consisting of convex portions is W1 and convex. W2 (W2> W1) is defined as a lower side corresponding to the base extended to reach the base of the perpendicular magnetic recording layer 10 made of a portion (a lower side corresponding to the bottom of the magnetic layer made of a convex extending the first trapezoidal shape). ), The gap length between adjacent lower sides W2 is W3, and in the second trapezoidal shape in the track circumferential direction that can be seen on the left and right side surfaces of the drawing, the perpendicular magnetic recording layer 10 made of convex portions The upper side corresponding to the surface is L1, and the lower side corresponding to the base extended to reach the base of the perpendicular magnetic recording layer (magnetic layer) 10 consisting of convex portions (the magnetic layer consisting of convex portions extending the second trapezoidal shape) The bottom corresponding to the bottom of ) Is L2 (L2> L1), the gap length between adjacent lower sides L2 is L3, and the total thickness of the magnetic layer in the convex region (the distance from the upper side to the lower side of the convex magnetic layer) is t. And the thickness of the magnetic layer (residual magnetic layer 10a) remaining under the recess is δ.

The magnetic characteristics in the direction perpendicular to the film surface of the convex magnetic layer (perpendicular magnetic recording layer 10) show M (magnetization) -H (magnetic field) characteristics as shown in FIG. When the coercivity in the direction perpendicular to the film surface of the magnetic recording layer 10) is Hc, the saturation magnetization is Ms, and the coercivity squareness ratio is S ^* , the coercivity squareness ratio S ^* takes a value of 0.8 or more. In addition, the convex shape (including the magnetic layer under the concave portion) is determined so as to satisfy the relationship of the following formula (1), and the magnetic characteristics of the perpendicular magnetic recording layer are set to determine the specifications of the burst portion. Is required.
For each unit, the unit shown in the table of the following examples is applied.

The coercive force squareness ratio S ^* is a value determined by the slope of the tangent at the point −Hc of the MH curve corrected by the demagnetizing field shown in FIG. 7 and the value of Mr, and the coercivity squareness ratio S ^*. Is defined by S ^* = Hc ′ / Hc. Hc ′ indicates the coercive force value at the intersection of the tangent line at the point −Hc of the MH curve and the straight line M = Mr in the second quadrant as shown in FIG. The meaning of “corrected for the demagnetizing field” means that the applied magnetic field is demagnetized by the product of the perpendicular demagnetizing coefficient and the magnetization of the perpendicular magnetic recording layer with respect to the magnetization value magnetized by the applied magnetic field. It corrects and calculates | requires a MH curve.

The expression on the right side of the above expression (1) indicates the magnitude of the demagnetizing field when the saturation magnetization Ms is recorded in the trapezoidal magnetic layer formed by the concave-convex pattern shown in FIG. By reversing the magnetization recorded on the convex portion by increasing the product value Hc ′ (= Hc · S ^* ) of the coercive force Hc and the coercive force squareness ratio S ^* , rather than the value of the demagnetizing field that reduces the magnetization. As a result, it has been found that long-term stability can be secured by suppressing deterioration of the servo signal.

At this time, the value of the coercive force squareness ratio S ^* must be 0.8 or more (preferably 0.85 to 1.0, more preferably 0.9 to 1.0. is there). When the value of the coercive force squareness ratio S ^* is less than 0.8, the squareness ratio of the MH curve is reduced, and a demagnetizing field is applied to the magnetization in the perpendicular magnetic recording layer. This causes a disadvantage that the magnetization is easily reversed due to the thermal fluctuation. In the case of a discrete pattern in a so-called discrete medium, the influence of the demagnetizing field becomes extremely large unlike the conventional continuous medium.

The magnitudes of the coercive force Hc and the coercive force squareness ratio S ^* can be changed by selecting the material of the magnetic recording layer, the underlying film, the film forming method, and the like.

  Moreover, by making the convex part into a trapezoidal shape, the demagnetizing field can be reduced as compared with the rectangular concave-convex structure, and it becomes easy to realize the setting specification that can achieve the effect of the present invention. Therefore, an extremely high magnetization stabilizing effect can be obtained by setting the convex portion to a trapezoidal shape as in the relational expression (1) and setting the convex portion to satisfy the dimensions and magnetic characteristics.

  Here, the length of L2 is a bit length corresponding to the frequency of the burst pattern, and the trapezoidal L1 is smaller than L2. W1 usually corresponds to the track width of the perpendicular magnetic recording medium. By making the cross-sectional shape in the track width direction and the track circumferential direction into a trapezoidal shape, the demagnetizing field can be reduced as compared with the rectangular uneven structure. This is because the surface area of the perpendicular magnetic recording layer corresponding to the upper side is reduced, and the demagnetizing field is accordingly reduced. In addition, the trapezoidal shape referred to in the present invention preferably has an angle θ of the base portion in the range of 55 ° to 85 °, and more preferably in the range of 65 ° to 80 °. Incidentally, in the case of a rectangular shape, the angle θ of the base is 90 °.

  Points to be considered when calculating the above equation (1) using the trapezoidal convex shape model shown in FIG. 4 are as follows.

  That is, in the case of a discrete medium, adjacent bits are isolated unlike a continuous medium, and therefore, the value of the demagnetizing field Hd was obtained as a demagnetizing field in a specific pattern. The demagnetizing field surrounds the trapezoidal structure at the center point of the trapezoidal structure to obtain a representative size and the magnetic field generated from the magnetic charge induced by the perpendicular magnetization M on the top and bottom of the pattern ( It was determined by superimposing the magnetic fields generated from the upper and lower surfaces of the magnetic layer located under the concave portion that was dug in (four locations along the side of the convex portion).

Further, when the residual magnetization of the magnetic layer formed with the concavo-convex pattern is Mr, the relationship of the following formula (2) is satisfied with respect to the magnetic layer formed with the concavo-convex pattern similar to the formula (1). Thus, it is necessary to determine the form of the magnetic layer formed by the uneven pattern and to set the magnetic characteristics of the perpendicular magnetic recording layer to determine the specifications of the burst portion.
For each unit, the unit shown in the table of the following examples is applied.

Note that the points considered in the induction of equation (2) are the same as in equation (1).

The expression on the right side of Expression (2) indicates the magnitude of the demagnetizing field in a state where saturation recording is performed on the trapezoidal convex magnetic layer formed by the concave / convex pattern shown in FIG. 4 and the magnetization becomes the residual magnetization Mr. Therefore, by increasing the value Hc ′ (= Hc · S ^* ) of the coercive force Hc and the coercive force squareness ratio S ^* from the value of the demagnetizing field that reduces the recorded magnetization, It has been found that long-term stability can be ensured by suppressing the reversal of recorded magnetization and suppressing a decrease in servo signal due to a decrease in recorded magnetization.

At this time, as described above, the value of the coercive force squareness ratio S ^* needs to be 0.8 or more (preferably 0.85 to 1.0, more preferably 0.9 to 1). .0). When the value of the coercive force squareness ratio S ^* is less than 0.8, the squareness ratio of the MH curve is reduced, and a demagnetizing field is applied to the magnetization in the perpendicular magnetic recording layer. This causes a disadvantage that the magnetization is easily reversed due to the thermal fluctuation. In the case of a discrete pattern in a so-called discrete medium, the influence of the demagnetizing field becomes extremely large unlike the conventional continuous medium.

Therefore, if the value of the coercive force squareness ratio S ^* and the expression (2) are satisfied, the lower limit value of the magnetization stability becomes smaller than that in the case of the saturation magnetization Ms, but the medium has a demagnetizing field due to residual magnetization. The coercive force is exceeded, the change with time of the decrease in magnetization due to thermal fluctuation is suppressed, and long-term stability is ensured.

  Also, as shown in FIG. 4, the length of the sum of L2 and L3 is equal to the wavelength of the servo signal recorded here. Although L2 and L3 are generally equal, the relative magnitude relationship may be changed depending on the signal waveform processing. That is, since the total length of L2 and L3 constitutes a length of one wavelength, the 1-bit length can be arbitrarily changed depending on the setting of L2 and L3.

  The gray code area of the so-called servo pattern corresponds to the sector address numbers (combined with various “0” and “1” patterns) as shown in the plan view of FIG. It may take various shapes as shown. In other words, it is not limited to the two types of outline rectangle and strip as described above (for example, as shown in FIG. 4). Therefore, in the case of a pattern as shown in FIG. 8, if each area point is viewed, it can be basically decomposed into a rectangular pattern, and the present invention may be applied to the decomposed pattern.

(2) Description of the second group As described above, the convex shape of the perpendicular magnetic recording layer 10 composed of convex portions satisfying the requirements of the second group is the ISG portion 91, SVAM portion 92, gray code portion 93, pad portion. 95 shapes fall under this category. Each of these portions has a belt-like convex portion 10 extending in the track width direction (track radial direction) as shown in FIG.

  In the track circumferential direction, the belt-like convex portion 10 has an upper side L1 corresponding to the surface of the magnetic layer made of the convex portion, and a lower side corresponding to the bottom side extended to reach the base of the magnetic layer made of the convex portion (second side It has a trapezoidal shape of a lower side L2 (L2> L1) corresponding to the bottom side of the magnetic layer made of a convex portion extending from a trapezoidal shape, and is at least 100 times the length of L2 in the track width direction (track radial direction). It has a belt-like convex shape with a length.

Then, the gap length between the adjacent lower sides L2 of the belt-like convex part 10 is L3, the total thickness of the magnetic layer in the convex part region (distance from the upper side to the lower side of the convex magnetic layer) is t, The thickness of the magnetic layer remaining under the concave portion is δ, the coercive force in the direction perpendicular to the film surface of the magnetic layer of the belt-like convex portion is Hc, the saturation magnetization is Ms, and the coercive force squareness ratio is S ^* . Then, the shape of the belt-like convex part (including the magnetic layer under the concave part) is determined so that the coercive force squareness ratio S ^* takes a value of 0.8 or more and satisfies the relationship of the following formula (3). At the same time, it is necessary to set the magnetic characteristics of the perpendicular magnetic recording layer to determine the specifications of the belt-like convex portions.
For each unit, the unit shown in the table of the following examples is applied.

The expression on the right side of the above equation (3) indicates the magnitude of the demagnetizing field when the saturation magnetization Ms is recorded on the belt-like convex portion (band-like long rectangular parallelepiped shape) shown in FIG. The magnetization reversal recorded in the belt-shaped convex portion is made larger by increasing the product value Hc ′ (= Hc · S ^* ) of the coercive force Hc and the coercive force squareness ratio S ^* than the value of the demagnetizing field. As a result, it was found that long-term stability can be secured by suppressing the deterioration of the servo signal.

At this time, as described above, the value of the coercive force squareness ratio S ^* needs to be 0.8 or more (preferably 0.85 to 1.0, more preferably 0.9 to 1). .0). When the value of the coercive force squareness ratio S ^* is less than 0.8, the squareness ratio of the MH curve is reduced, and a demagnetizing field is applied to the magnetization in the perpendicular magnetic recording layer. This causes a disadvantage that the magnetization is easily reversed due to the thermal fluctuation. In the case of a discrete pattern in a so-called discrete medium, the influence of the demagnetizing field becomes extremely large unlike the conventional continuous medium.

The magnitudes of the coercive force Hc and the coercive force squareness ratio S ^* can be changed by selecting the material of the magnetic recording layer, the underlying film, the film forming method, and the like.

  Moreover, by making the convex part into a trapezoidal shape, the demagnetizing field can be reduced as compared with the rectangular concave-convex structure, and it becomes easy to realize the setting specification that can achieve the effect of the present invention. Therefore, an extremely high magnetization stabilizing effect can be exhibited by setting the belt-like convex portion to a trapezoidal shape as in the relational expression (3) and satisfying the size and magnetic characteristics of the convex portion.

In calculating the above formula (3) using the trapezoidal convex shape model which is the belt-like convex portion shown in FIG. 5, the points considered are basically the case of derivation of the above-described formula (1) and The same thing can be considered, but the difference in the calculation is that the length in the track circumferential direction is L1, and the length in the track radial direction is a strip shape having a length of 100 times or more the length of L1. Therefore, there are many terms that can be approximated to zero. As a result, it becomes a simple formula like Formula (3).
Further, when the residual magnetization of the perpendicular magnetic recording layer 10 of the convex portion is Mr, the band-like convex portion satisfies the relationship of the following formula (4) with respect to the trapezoidal shape similar to the formula (3). (Including the magnetic layer under the concave portion) and the magnetic characteristics of the perpendicular magnetic recording layer must be set to determine the specifications of the belt-shaped convex portion.
For each unit, the unit shown in the table of the following examples is applied.

Note that the points considered in the induction of equation (4) are the same as in equation (3).

The expression on the right side of Expression (4) indicates the magnitude of the demagnetizing field in a state where saturation recording is performed on the belt-like convex portion shown in FIG. 5 and the magnetization becomes the residual magnetization Mr. By increasing the product value Hc ′ (= Hc · S ^* ) of the coercive force Hc and the coercive force squareness ratio S ^* rather than the numerical value of the magnetic field, reversal of the magnetization recorded on the convex portion is suppressed, and recording is performed. It was found that long-term stability can be ensured by suppressing deterioration of the servo signal due to the decrease in magnetization.

At this time, the value of the coercive force squareness ratio S ^* must be 0.8 or more (preferably 0.85 to 1.0, more preferably 0.9 to 1.0. is there). When the value of the coercive force squareness ratio S ^* is less than 0.8, the squareness ratio of the MH curve is reduced, and a demagnetizing field is applied to the magnetization in the perpendicular magnetic recording layer. This causes a disadvantage that the magnetization is easily reversed due to the thermal fluctuation. In the case of a discrete pattern in a so-called discrete medium, the influence of the demagnetizing field becomes extremely large unlike the conventional continuous medium.

The magnitudes of the coercive force Hc and the coercive force squareness ratio S ^* can be changed by selecting the material of the magnetic recording layer, the underlying film, the film forming method, and the like.

Therefore, if the value of the coercive force squareness ratio S ^* and the expression (4) are satisfied, the lower limit value of the magnetization stability becomes smaller than that in the case of the saturation magnetization Ms, but the medium retention with respect to the demagnetizing field due to the residual magnetization. The magnetic force is increased, the change over time of the decrease in magnetization due to thermal fluctuation is suppressed, and long-term stability is ensured.

  As shown in FIG. 5, the length of the sum of L2 and L3 is equal to the wavelength of the servo signal recorded here. Although L2 and L3 are generally equal, the relative magnitude relationship may be changed depending on the signal waveform processing. That is, since the total length of L2 and L3 constitutes a length of one wavelength, the 1-bit length can be arbitrarily changed depending on the setting of L2 and L3.

  Note that, in the trapezoidal convex perpendicular magnetic recording layer described above, the demagnetizing field due to the recording magnetization is further reduced even in the shape where the upper corner is lowered, so the relational expression shown above If it is almost satisfied, long-term stability can be obtained even in a shape in which the upper corner is lowered.

  Further, recording for servo signals in the servo area according to the present invention is performed in such a manner that the perpendicular magnetic recording medium 10 is perpendicular to the perpendicular magnetic recording layer surface in a DC magnetic field and has a strength greater than or equal to the external magnetic field Hn in the magnetic field-magnetization curve of FIG. Is applied to collectively carry out saturation magnetization. Therefore, the perpendicular magnetic recording media of the data information recording portion (so-called data region) and the tracking servo information portion (so-called servo region) are all saturated and magnetized uniformly in either direction.

In the discrete media servo information section of the present invention, the demagnetizing field from the adjacent bits is small but not completely zero. Therefore, the coercive force Hc and the coercive force squareness ratio S ^* are larger than those of the isolated bits. It is desirable to adopt the product value Hc ′ (= Hc · S ^* ).

  Hereinafter, the present invention will be described in more detail with reference to specific examples.

(Configuration of magnetic recording medium)
As shown in FIG. 1, the disk surface is divided into sectors, and a servo area 90 as shown in FIG. 2 is formed in order to apply the sector servo system. That is, the ISG part 91, the SVAM part 92, the gray code part 93, the burst part 94, and the pad part 95 were formed according to the pattern of each servo signal.

  The convex part of the burst part 94 for recording the burst signal was a trapezoidal (quadrangular pyramid) perpendicular magnetic recording layer as shown in FIG. The other convex portions in the ISG portion 91, the SVAM portion 92, the gray cord portion 93, and the pad portion 95 are perpendicular magnetic portions of a belt-like convex portion (band-shaped square frustum shape) long in the disk radial direction as shown in FIG. The recording layer was arranged at intervals of 1 bit.

  As shown in FIG. 3, the cross-sectional shape of the medium is such that a PtMn layer is formed as a alignment layer 14 (underlayer 14) with a thickness of 15 nm on a mirror-polished glass substrate 15, and a soft magnetic layer made of CoZrNb is formed thereon. Layer 11 was formed to a thickness of 200 nm. On this, an intermediate layer 12 made of Ru was formed to a thickness of 8 nm. Next, a perpendicular magnetic recording layer 10 was formed thereon so that its thickness t was 15 nm, and then a predetermined pattern etching process was performed to produce a predetermined uneven shape. The thickness δ of the magnetic layer under the recess (residual magnetic layer) was left to be 6 mm.

Next, SiO ₂ was sputtered to fill the etched recesses. Next, while rotating the medium filled with SiO ₂ , an oblique ion beam etching process was performed to remove excess SiO ₂ formed on the perpendicular magnetic recording layer 10 and to flatten the surface of the medium. A protective film 13 of carbon thin film was formed thereon with a thickness of 4 nm by CVD, and a fomblin lubricant was applied to a thickness of 1 nm to complete a medium sample. The perpendicular magnetic recording layer 10 was made of a material in which ferromagnetic particles of CoPt were included in a matrix in SiO ₂ .

  The recording density of the servo signal was 130K · FRPI (Flux Reversal Per Inch). Accordingly, the values of L2 and L3 in FIGS. 4 and 5 are each 195 nm.

  The track pitch of the data area was set to 85 nm corresponding to 298.8 K · TPI (Track Per Inch). The length W2 in the track width direction and the burst gap W3 in the track width direction corresponding to the burst pattern shown in FIG.

  The above-described perpendicular magnetic recording medium processed to have irregularities for the predetermined servo area and data area has an electromagnet in which a DC magnetic field of 15 kOe (1193 kA / m) is generated in order to magnetize the perpendicular magnetic recording layer of the convex portion that generates the servo signal magnetic field. The disc surface was set so that the disk surface was parallel to the magnetic pole surface, and trapezoidal perpendicular magnetic recording layers in the servo area and the data area were collectively magnetized to record servo signals.

For the measurement of the magnetic properties of the medium, using a vibrating sample magnetometer and (VSM), the coercive force Hc, the ratio S ^* is a coercive force squareness, after forming, the demagnetizing field correction of the magnetic recording layer not processed go Numerical values were used. In the case of a perpendicular magnetic recording medium, a strong demagnetizing field is generated when the film is magnetized in a perpendicular direction to the film surface, so that the magnetization M-magnetic field H curve changes due to a change in film thickness. Note that the saturation magnetization Ms and the residual saturation magnetization Mr of the perpendicular magnetic recording layer used were Ms = 360 emu / cc (360 kA / m) and Mr = 350 emu / cc (350 kA / m).

  In order to examine the time-dependent change of the servo signal of the magnetized perpendicular magnetic recording medium, the reproduction GMR head is on-tracked to the burst part, the ISG part, the SVAM part, and the gray code part, and the change over time of each reproduction output is measured. Went.

  The track width of the reproducing GMR head was 85 nm. The change in reproduction output with time was measured by a GMR head immediately after magnetizing with an electromagnet. Thereafter, measurement was continuously performed for 3 months, and a change in reproduction output was measured.

  The experimental specifications were divided into the following four types and will be described individually.

(Experimental specification 1)
In the examples, comparative examples, and reference examples shown in Table 1 below, the recording density of the servo signal is 130 K · FRPI (Flux Reversal Per Inch) as described above, and FIG. 4 and FIG. The value of L2 and L3 indicated by 5 is 195 nm. Also, the track pitch of the data area as described above is 85nm corresponding to 298.8K · TPI (T rack P er I nch). Further, as described above, the W2 and W3 dimensions corresponding to the burst pattern of FIG. 4 are each 85 nm.

The parameters of the trapezoidal perpendicular magnetic recording layer of the burst pattern in the servo area in FIG. 4 and the values of the coercive force Hc and the coercive force squareness ratio S ^{* in} the direction perpendicular to the film surface of the perpendicular magnetic recording layer are changed. Reproduction output change was measured. The values of the coercive force Hc and the coercive force squareness ratio S ^* were changed by changing the underlayer conditions and the film forming method of the magnetic recording layer.

  In the change in the reproduction output, “×” indicates that the output decreased by 10% or more from the initial output after 3 months, and “◯” indicates that the output was within 10%. As an accelerated test, a medium having KuV / kT = 80 at 70 ° C., which is higher than the usual general maximum storage temperature of 60 ° C., is used, and this is measured at a storage temperature of 80 ° C. with KuV / kT = 70. did.

In Table 1, in order to clarify the effect of the relational expression of the present invention, the expression on the right side in the above expression (1) is α, the signs of “Hc-α” and “Hc′-α”, and the coercive force. The value of the squareness ratio S ^* is shown simultaneously. Hc ′ = Hc · S ^* . α is represented by the following formula (5).

As can be seen from the results shown in Table 1, trapezoidal perpendicular magnetism satisfying “Hc′−α> 0”, which is the relationship represented by the formula (1), and satisfying “S ^* ≧ 0.8” In the recording layer, demagnetization was suppressed even under conditions stricter than normal storage conditions, and it was confirmed that the desired effect of the present application was obtained. Note that when S ^* = 0.75, the coercive force increases and the squareness ratio (Mr / Ms) also decreases, and the expected characteristics cannot be obtained.

In Table 1, the magnitude of the demagnetizing field in the trapezoidal shape is 4123 Oe (328 kA / m) as can be seen from “Hc−α = 0” in S ^* = 1. On the other hand, the magnitude of the rectangular demagnetizing field shown in the reference example is 4148 Oe (330 kA / m).

(Experimental specification 2)
As an experimental specification 2, as shown in Table 2 below, a perpendicular magnetic recording medium having a magnetic layer structure formed with a concavo-convex pattern similar to the above experimental specification 1 was used, and this was maintained at a normal maximum storage temperature of 60 ° C. Reproduction output change was measured. Under this condition, KuV / kT = 93.3.

In Table 2, in order to clarify the effect of the relational expression of the present invention, the expression on the right side in the expression (2) is β, the signs of “Hc−β” and “Hc′−β”, and the coercive force. The value of the squareness ratio S ^* is shown simultaneously. Hc ′ = Hc · S ^* . β is represented by the following formula (6).

As can be seen from the results shown in Table 2, the trapezoidal perpendicular magnetism satisfying “Hc′−β> 0” which is the relationship represented by the formula (6) and satisfying “S ^* ≧ 0.8”. In the recording layer, demagnetization was suppressed even under normal maximum storage temperature conditions, and it was confirmed that the desired effect of the present application was obtained. Note that when S ^* = 0.75, the coercive force increases and the squareness ratio (Mr / Ms) also decreases, and the expected characteristics cannot be obtained.

(Experimental specification 3)
As shown in FIG. 5, the parameters of the magnetic layer (perpendicular magnetic recording layer) formed by the concavo-convex pattern corresponding to the ISG part, SVAM part, gray code part, etc. of the servo area, and the film surface of the perpendicular magnetic recording layer Changes in the reproduction output of the GMR head were measured by changing the values of the coercive force Hc and the coercive force squareness ratio S ^{* in} the vertical direction. The results are shown in Table 3 below.

  As with the above-mentioned experimental specification 1, the reproduction output change criterion was “X” when the output decreased by 10% or more from the initial output after the lapse of 3 months, and “◯” when it was within 10%. As an accelerated test, a medium having KuV / kT = 80 at 70 ° C., which is higher than the normal maximum storage temperature of 60 ° C., was used, and this was measured at 80 ° C. with KuV / kT = 70.

In Table 3, in order to clarify the effect of the relational expression of the present invention, the expression on the right side in the expression (3) is γ, the signs of “Hc−γ” and “Hc′−γ”, and the coercive force. The value of the squareness ratio S ^* is shown simultaneously. Hc ′ = Hc · S ^* . γ is represented by the following formula (7).

As can be seen from the results shown in Table 3, the trapezoidal perpendicular magnetism satisfying “Hc′−γ> 0”, which is the relationship represented by Expression (7), and satisfying “S ^* ≧ 0.8” In the recording layer, demagnetization was suppressed even under conditions stricter than normal storage conditions, and it was confirmed that the desired effect of the present application was obtained. Note that when S ^* = 0.75, the coercive force increases and the squareness ratio (Mr / Ms) also decreases, and the expected characteristics cannot be obtained.

(Experimental specification 4)
As the experimental specification 4, as shown in Table 4 below, a perpendicular magnetic recording medium having a magnetic layer structure formed with a concavo-convex pattern similar to the experimental specification 3 is used, and this is maintained at a normal maximum storage temperature of 60 ° C. Reproduction output change was measured. Under this condition, KuV / kT = 93.3.

In Table 4, in order to clarify the effect of the relational expression of the present invention, the expression on the right side in the above expression (4) is ε, the signs of “Hc−ε” and “Hc′−ε”, and the coercive force. The value of the squareness ratio S ^* is shown simultaneously. Hc ′ = Hc · S ^* , and ε is represented by the following formula (8).

As can be seen from the results shown in Table 4, trapezoidal perpendicular magnetism satisfying “Hc′−ε> 0” which is the relationship represented by the formula (8) and satisfying “S ^* ≧ 0.8”. In the recording layer, demagnetization was suppressed even under normal maximum storage temperature conditions, and it was confirmed that the desired effect of the present application was obtained. Note that when S ^* = 0.75, the coercive force increases and the squareness ratio (Mr / Ms) also decreases, and the expected characteristics cannot be obtained.

  From the above results, the effect of the present invention is clear. That is, the magnetic recording apparatus of the present invention can reduce the influence of the demagnetizing field that accelerates the thermal fluctuation of the perpendicular magnetic recording medium in the servo area of the perpendicular magnetic recording medium that is most strongly affected by the thermal fluctuation of the medium. Since the convex structure (magnetic layer formed by the concave / convex pattern) on which the servo signal is recorded is set according to the characteristics of the perpendicular magnetic recording medium to be used, the vertical magnetic recording of the concave / convex structure in the servo area is performed. Servo signal deterioration caused by thermal fluctuation of the magnetization of the layer can be suppressed, and a stable servo function can be ensured over a long period of time.

  The magnetic recording apparatus of the present invention is particularly used in a computer and can be used in the apparatus industry for information recording.

FIG. 1 is a schematic plan view showing the overall shape of a disk-shaped magnetic recording medium of the present invention. FIG. 2 is a partially enlarged schematic view of a minute portion surrounded by a square in FIG. 1 is a sectional view conceptually showing a preferred embodiment of a magnetic recording medium of the present invention. It is a schematic perspective view which shows the structure of a perpendicular magnetic recording layer. It is a schematic perspective view which shows the structure of a perpendicular magnetic recording layer. 1 is a schematic perspective view of a magnetic recording / reproducing apparatus. It is drawing which shows the magnetization-magnetic field curve of a magnetic recording medium. It is a top view for demonstrating an example of another servo pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording medium 2 ... Spindle motor 3 ... Voice coil motor 4 ... Rotary arm 5 ... Recording / reproducing magnetic head 10 ... Perpendicular magnetic recording layer 10a ... (under recessed part) Remaining magnetic layer 11 ... Soft magnetic layer 12 ... Intermediate layer 13 ... Protective film 14 ... Orientation layer 20 ... Nonmagnetic layer 80 ... Data information recording part 90 ... Servo information part 91 ... ISG part 92 ... SVAM part 93 ... Gray code part 94 ... Burst part 95 ... Pad part

Claims (8)

A perpendicular magnetic recording medium having a data information recording part and a servo information part for tracking; and a magnetic head for detecting servo information in the servo information part and recording and reproducing data information in the data information recording part A magnetic recording / reproducing apparatus,
The servo information part is composed of a convex pattern of the perpendicular magnetic recording layer formed in a predetermined concavo-convex pattern, and the inside of the concave pattern is filled with a nonmagnetic material, and the servo information part is , Including a burst portion for recording a tracking burst signal,
The burst portion is formed by arranging a perpendicular magnetic recording layer composed of a plurality of convex portions in which a burst signal is recorded,
The perpendicular magnetic recording layer composed of the convex portions has a first trapezoidal shape and a second trapezoidal shape in the track width direction (track radius direction) and the track circumferential direction, respectively.
In the first trapezoidal shape in the track width direction, the upper side corresponding to the surface of the perpendicular magnetic recording layer made of the convex portion is W1, and the upper side corresponding to the base of the perpendicular magnetic recording layer made of the convex portion is extended. The lower side (the lower side corresponding to the bottom of the perpendicular magnetic recording layer made of the convex portion extending from the first trapezoidal shape) is W2 (W2> W1), and the gap length between adjacent lower sides W2 is W3.
In the second trapezoidal shape in the track circumferential direction, the upper side corresponding to the surface of the perpendicular magnetic recording layer made of the convex portion is L1, and the bottom side extended to reach the base of the perpendicular magnetic recording layer made of the convex portion L2 (where L2> L1) , and the gap length between adjacent lower sides L2 is L3 ( the lower side corresponding to the bottom side of the perpendicular magnetic recording layer formed of the convex portion extending the second trapezoidal shape )
The total thickness of the perpendicular magnetic recording layer in the convex region (the distance from the upper side to the lower side of the convex perpendicular magnetic recording layer ) is t, and the thickness of the perpendicular magnetic recording layer remaining under the concave is δ. When the coercivity in the direction perpendicular to the film surface of the perpendicular magnetic recording layer of the convex portion is Hc, the saturation magnetization is Ms, and the coercivity squareness ratio is S ^* ,
A magnetic recording / reproducing apparatus, wherein the coercivity squareness ratio S ^* has a value of 0.8 or more, and the specifications of the burst portion are set so as to satisfy the relationship of the following formula (1).

When the coercive force in the perpendicular direction of the perpendicular magnetic recording layer composed of the convex portions is Hc, the residual magnetization is Mr, and the coercive force squareness ratio is S ^* ,
2. The magnetic recording / reproducing apparatus according to claim 1, wherein the specifications of the burst portion are set so that the coercive force squareness ratio S ^* takes a value of 0.8 or more and satisfies the relationship of the following formula (2).

And L2 is a lower side corresponding to the perpendicular magnetic recording layer in the form of the convex portion, the sum of the a gap of the perpendicular magnetic recording layer L3 formed by setting the wavelength of the frequency of the servo signal according to claim 1 or claim 2 2. A magnetic recording / reproducing apparatus according to 1. A perpendicular magnetic recording medium having a data information recording part and a servo information part for tracking; and a magnetic head for detecting servo information in the servo information part and recording and reproducing data information in the data information recording part A magnetic recording / reproducing apparatus,
The servo information part is composed of a convex pattern of the perpendicular magnetic recording layer formed in a predetermined concavo-convex pattern, and the inside of the concave pattern is filled with a nonmagnetic material, and the servo information part is , Having an ISG portion, an SVAM portion, a gray cord portion, a belt-like convex portion extending in the track radial direction (track width direction) for forming the pad portion ,
The belt-like convex portions are, in the track circumferential direction, an upper side L1 corresponding to the surface of the perpendicular magnetic recording layer made of the convex portion, and a lower side corresponding to the bottom side extended to reach the base of the perpendicular magnetic recording layer made of the convex portion. (Lower side corresponding to the bottom side of the perpendicular magnetic recording layer consisting of convex portions extending from the second trapezoidal shape) L2 (where L2> L1) and a trapezoidal shape of L2 in the track radial direction. It has a band shape with a length of more than double,
Let L3 be the gap length between the adjacent lower sides L2 of the belt-like convex portion, and the total thickness of the perpendicular magnetic recording layer in the convex portion region (distance from the upper side to the lower side of the perpendicular magnetic recording layer of the convex portion) is t. Where δ is the thickness of the perpendicular magnetic recording layer remaining under the concave portion, Hc is the coercive force perpendicular to the film surface of the perpendicular magnetic recording layer of the belt-like convex portion, Ms is the saturation magnetization, and the coercive force angle is When the mold ratio is S ^* ,
A magnetic recording / reproducing apparatus, wherein the coercive force squareness ratio S ^* takes a value of 0.8 or more, and the specifications of the belt- like convex portions are set so as to satisfy the relationship of the following formula (3).

When the coercive force in the direction perpendicular to the film surface of the perpendicular magnetic recording layer of the belt-like convex portion is Hc, the residual magnetization is Mr, and the coercive force squareness ratio is S ^* ,
5. The magnetic recording / reproducing apparatus according to claim 4 , wherein the specifications of the belt-like convex portions are set so that the coercive force squareness ratio S ^* takes a value of 0.8 or more and satisfies the relationship of the following formula (4). .

And L2 is a lower side corresponding to the perpendicular magnetic recording layer in the form of the convex portion, claim 4 the sum of the L3 is a gap between perpendicular magnetic recording layer in the form of the convex portion formed by setting the wavelength of the frequency of the servo signal Alternatively, the magnetic recording / reproducing apparatus according to claim 5 . Recording for servo signal in the servo information portion, by applying perpendicular to the perpendicular magnetic recording layer of the perpendicular magnetic recording medium in a DC magnetic field during the claims 1 formed by collectively magnetization of claim 6 The magnetic recording / reproducing apparatus in any one. 8. The magnetic recording / reproducing apparatus according to claim 1, wherein the servo information section is formed in a predetermined uneven pattern, and the recess is filled with a nonmagnetic material for exerting a discrete action. apparatus.

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