JP2001160214A - Magnetic recording medium and magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium wherein frictional force generated when a magnetic head comes into contact with the magnetic recording medium at the time of recording and reproduction is low while keeping low noise characteristics which is important for realizing high recording density and wherein high sliding reliability can be secured and to provide a magnetic disk device using the magnetic recording medium. SOLUTION: The magnetic recording medium having a magnetic alloy layer consisting essentially of Co, a protective layer and a lubricating layer which are formed in this order on a substrate through a base is characterized in that the base is constituted of a plurality of base layers including a structure having a first base layer consisting essentially of an amorphous layer and a second base layer consisting of a crystalline layer which are laminated in this order and the difference ΔBH[0.01, 50] (=|BH[0.01%]-BH[50%]|) between a height BH[0.01%] and a height BH[50%] corresponding to the heights where the load ratio is 0.01% and 50%, respectively, in the load curve obtained from the surface roughness curve of the magnetic recording medium is >=3 nm and <=6 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium capable of recording a large amount of information and a magnetic storage device using the same, and more particularly to a magnetic recording medium and a magnetic disk device suitable for high-density magnetic recording.

[0002]

2. Description of the Related Art The demand for large capacity magnetic storage devices is increasing at present. In order to increase the recording density, (1) increase the sensitivity of the magnetic head reproducing section, (2) shorten the distance between the head element and the recording film of the magnetic recording medium,
(3) Higher efficiency of signal processing.

[0003] In recent years, the adoption of a composite magnetic head in which a magnetic head is separated into a recording section and a reproducing section and an element utilizing a highly sensitive magnetoresistive effect is used in the reproducing section has been rapidly advanced. Also, recently, in order to further improve the sensitivity of the head reproducing section, a very large magnetoresistance change (giant magnetoresistance effect or spin valve effect) generated in a magnetic layer in which a plurality of magnetic layers are stacked via a nonmagnetic layer. Magnetic heads utilizing the same have been put to practical use. This is because the relative magnetization directions of the plurality of magnetic layers via the non-magnetic layer change due to the leakage magnetic field from the medium,
This utilizes the fact that the magnetic resistance changes.

On the other hand, factors necessary for increasing the recording density of the magnetic recording medium include (1) lowering the noise of the magnetic recording medium corresponding to the improvement in the sensitivity of the magnetic head reproducing section, and (2) reducing the noise between the head element and the magnetic recording medium. Distance from recording film (spacing)
And (3) reduction in the thickness of the protective layer.

For the magnetic layer of the magnetic recording medium, CoNiC
In-plane magnetic recording media using alloys containing Co as a main component such as r, CoCrTa, CoCrPt, and CoCrPtTa are widely used. In particular, a Co alloy magnetic film containing Pt has a high coercive force,
Since the output in the high linear recording density region can be increased, it is suitable for high recording density. These Co alloys have a hexagonal close-packed structure (hcp structure) with the c-axis as the axis of easy magnetization. For use as an in-plane magnetic recording medium, the c-axis is desirably oriented in the plane. Therefore, a method of first forming a base layer having a body-centered cubic (bcc) structure on a substrate, epitaxially growing a Co alloy magnetic layer thereon, and directing the c-axis in-plane has been widely used.

Although Cr has been generally used as the underlayer, when the magnetic layer contains large atoms such as Pt,
Cr (Ti) (JP-A-63-197018) and V (JP-A-62-257618)
Using a Cr alloy underlayer with an increased lattice spacing to increase the lattice matching between the magnetic layer and the underlayer and to orient the c-axis of the magnetic layer parallel to the film plane (Japanese Patent Laid-Open No. -197018,
JP-A-62-257618) has been proposed. JP-A-63-187416 discloses that a wide range of materials including Mo, W, Hf and the like can be used as the material of the underlayer in addition to these materials. Further, as described in JP-A-10-143865, an amorphous alloy layer containing Co as a main component between the above Cr alloy base and the substrate and containing Cr or Zr with a high tendency to oxidize. It has been shown that medium noise can be reduced stably by forming the surface of the substrate and exposing the surface to an oxygen atmosphere to slightly oxidize the surface.

The following techniques have been proposed as techniques for improving the reliability of contact between a magnetic head and a magnetic recording medium. That is, JP-A-5-114127, JP-A-8-114
No. 297834 describes the surface shape of the magnetic recording medium suitable for avoiding head crash and medium damage caused by CSS (contact start / stop) performed when starting and stopping the device, considering the sliding reliability. Proposed. Also,
Japanese Patent Application Laid-Open No. H11-232638 proposes a surface shape for avoiding contact between a head and a medium. Japanese Patent Publication No. 7-95369 proposes a method of contributing a projection shape to the medium surface in order to improve the sliding reliability of a floppy disk using a contact type head.

Further, Japanese Patent Application Laid-Open No. 11-110933 discloses a magnetic head when the rotation of a medium is stopped in order to achieve both a reduction in surface roughness due to a reduction in spacing and an avoidance of a head sticking phenomenon when the magnetic head is stopped. Has been proposed to save the data outside the medium.

[0009]

According to the above-mentioned prior art, it has become possible to avoid the head sticking phenomenon on the magnetic recording medium and to reduce the noise of the magnetic recording medium due to the improvement of the sensitivity of the magnetic head reproducing section. However, recently, the spacing has been sharply reduced in order to achieve a high recording density, and an interface environment in which contact between the head and the medium is inevitable even during recording / reproducing is coming. Therefore, minimizing the loss of spacing with respect to the surface shape of the medium,
There is a demand for realizing high sliding reliability.

A first object of the present invention is to maintain a low noise characteristic which is important for realizing a high recording density, to have a low frictional force even in the low flying environment as described above, and to achieve a high sliding reliability. It is to provide a magnetic recording medium that can ensure the above. A second object is to provide a high-capacity magnetic storage device with high reliability.

[0011]

In order to solve the above problems, a magnetic alloy layer containing Co as a main component, a protective layer containing C as a main component, and a lubricating layer are formed on a substrate in this order via an underlayer. With respect to the formed magnetic recording media, magnetic recording media having different layer configurations of the underlayer and surface shapes of the media were manufactured, and their characteristics were evaluated. As a result, the underlayer is substantially amorphous.
A load curve determined from a surface roughness curve of the magnetic recording medium is composed of a plurality of underlayers including a structure in which one underlayer and a crystalline second underlayer are laminated in this order. [BH [0.01, 50] = | BH [0.01%]-BH, the difference between the height BH [0.01%] at which the load becomes 0.01% and the height BH [50%] at which the load ratio becomes 50%
[50%] | was set to 3 nm or more and 6 nm or less, good results were obtained, and it was found that the first object of the present invention could be achieved.

[0012] By forming a substantially amorphous layer as the first underlayer, the crystal of the second underlayer, which is a crystalline layer formed thereon, can be made finer. Medium noise is reduced by making the crystal grains of the magnetic layer formed thereon finer. Further, by making the first underlayer substantially amorphous, it is possible to suppress the growth of abnormally large crystal grains observed in the growth process of a crystalline film. As a result, the probability of contact between the slider and the medium when the flying height of the magnetic head slider is reduced can be reduced, so that both low noise and high reliability of the medium can be achieved. Here, “substantially amorphous” is defined as indicating that a diffraction pattern is observed as a halo when a selected area diffraction image is taken with a transmission electron microscope. The fine structure of the layers constituting such a magnetic recording medium can be obtained by thinning the sample perpendicular to the substrate surface or thinning the substrate by mechanical polishing from both the top and bottom of the sample surface by ion thinning. It can be evaluated by thinning the film and observing the relevant portion with a transmission electron microscope at a high magnification, or observing the pattern of the diffraction ring with a selected area diffraction image.

The material constituting the first underlayer is CoC
rZr, NiCrZr, CoP, NiP and the like can be used. By using Co or Ni as the main component of the first underlayer, high adhesion strength to the substrate can be obtained. Furthermore, by adding Cr or P as an additive element, the ferromagnetic component of Co or Ni contained in the first underlayer can be effectively reduced, and the magnetization of the first underlayer can be ignored when viewed from the read head. It can be as small as possible. For alloys containing Ni or Co as the main component and containing both Cr and Zr, high corrosion resistance can be obtained especially by adding Cr. In addition, the addition of Zr makes the first alloy without deteriorating the corrosion resistance. This is particularly preferable because the underlayer can be made amorphous. P
When P is added, the addition of P can simultaneously realize the effective reduction of the ferromagnetic component of Co or Ni and the amorphization at the same time. By exposing the surface of CoCrZr, NiCrZr, NiP, etc. to an oxygen atmosphere and slightly oxidizing the surface, the crystal grains underlying the Cr alloy formed thereon can be made finer. A (100) orientation that can be oriented parallel to the film plane can be used. Thereby, the medium noise can be reduced stably. It should be noted that even if Cr, Ti, V, Mo, and Nb are added in place of Cr added to the first underlayer, almost the same effect as that of Cr can be obtained. In addition, the first
Even if Ta, Hf, Y, and W are added in place of Zr added to the underlayer, substantially the same effect as in the case of Zr can be obtained. The thickness of the first underlayer is preferably 20 nm or more and 80 nm or less. If the thickness is less than 30 nm, breakage of the medium due to contact with the head is likely to occur. On the other hand, the thickness is 80
If it exceeds nm, the efficiency of mass production decreases, which is not preferable.
It is particularly preferable that the thickness of the first underlayer is in the range of 30 nm or more and 65 nm or less because particularly high reliability and mass production efficiency can be realized.

Preferably, the crystal structure of the second underlayer is a nonmagnetic metal having a body-centered cubic structure. For example, a thin film of a nonmagnetic Cr-based alloy or the like that forms a solid solution having a (100) orientation that is expected to have good crystal matching with the magnetic layer is used. Here, the (100) orientation means that the (100) plane of the crystal is oriented parallel to the substrate surface. The material of the second underlayer is Cr
Ti alloy, CrTiMo alloy, CrMo alloy or the like can be used. The thickness of the second underlayer is preferably 3 nm or more and 60 nm or less. When the thickness is less than 3 nm, it becomes difficult to control the crystallinity and crystal orientation of the magnetic layer formed thereon, and when the thickness is more than 60 nm, sudden abnormalities in crystal grains occur. Growth is likely to occur, which is a factor that hinders floating, and reduces the efficiency of mass production, which is not preferable. It is particularly preferable that the thickness of the second underlayer is 15 nm or more and 35 nm or less because a medium having low noise and excellent low flying reliability can be efficiently produced. If the second underlayer is a CrTi alloy, Ti
It is preferable that the addition concentration is 18 at.% Or more and 23 at.% Or less. The Ti addition concentration of the second CrTi alloy underlayer is 18 at.
If it is less than the above, the crystal matching with the magnetic layer formed thereon is deteriorated. On the other hand, if the Ti addition concentration exceeds 23 at.%, The crystal grains of the underlayer become large, and the crystal grains of the magnetic layer formed continuously on this underlayer also become large, which is not preferable because the medium noise increases.

Further, in the load curve obtained from the surface roughness curve of the magnetic recording medium, the difference between the height BH [0.01%] at which the load ratio becomes 0.01% and the height BH [50%] at which the load ratio becomes 50%. ΔB
H [0.01, 50] (= | BH [0.01%]-BH [50%] |) is 3nm or more,
By setting the thickness to 6 nm or less, even when the head slider comes into contact with the medium, the frictional force can be suppressed to a low level, thereby ensuring higher sliding reliability. In particular, by making the surface shape of the medium on which the substantially amorphous layer is formed as the first underlayer satisfy the above conditions as described above, low noise, low flying and high reliability can be obtained. Are both preferred. If ΔBH [0.01, 50] is less than 3 nm, the frictional force generated when the head comes in contact with the medium increases, and the life in the continuous sliding test is shortened. Further, the head vibrates in the pitch direction, and recording and reproduction become unstable, which is not preferable. On the other hand, if ΔBH [0.01, 50] exceeds 6 nm, the spacing between the head slider and the medium cannot be reduced, and a high recording density exceeding 10 gigabits per inch cannot be achieved. ΔBH [0.01, 50] is 3n
The difference between the height BH [0.01%] at which the load ratio is not less than m and 6 nm and the load ratio is 0.01% and the height BH [0.8%] at which the load ratio is 0.8% is ΔBH [0.01, 0.8] (= | BH [0.01%]-BH [0.8%] |) is 3 nm or less, which is a more preferable shape in order to ensure high sliding reliability. If ΔBH [0.01, 0.8] exceeds 3 nm, the life in a continuous sliding test is shortened, which is not preferable. In order to further improve the reliability during continuous contact, in the load curve obtained from the surface roughness curve of the magnetic recording medium, the height BH [1%] where the load ratio becomes 1% and the height BH [1%] where the load ratio becomes 50% Sa BH [50
%] Is y (= | BH [1%]-BH [50%] |), and the load ratio is 1
Height BH [15%] that becomes 5% and height BH [50 that makes the load ratio 50%
%] Is x (= | BH [15%]-BH [50%] |), the point represented by the coordinates (x, y) is the point (0.1, 1.6) on the xy plane. A line connecting point (1, 3), a line connecting point (1, 3) and point (1, 4), a line connecting point (1, 4) and point (0.1, 4), Further, it is preferable that the arithmetic mean roughness (Ra) is within an area surrounded by a line segment connecting the point (0.1, 4) and the point (0.1, 1.6).
Most preferably, it is 0.7 nm or less. Outside the above range, the life in the continuous contact test is shortened by one digit or more.

In order to achieve a high recording density exceeding 20 gigabits per inch, ΔBH [0.01, 50] is preferably 3 nm or more and 4 nm or less from the viewpoint of low flying height.

Here, the load curve is a load curve proposed by Abbott, and the load ratio is defined by Japanese Industrial Standards (JI
It refers to the load length ratio described in SB 0601) (Reference:
Yamamoto and Kaneda, "Tribology," p. 23, Science and Engineering.
Arithmetic mean roughness (Ra) is defined as Japanese Industrial Standard (JIS B 06
01) is the roughness expression described.

As a method of forming the surface shape of the magnetic recording medium as described above, the substrate surface is subjected to machining or chemical surface treatment so that ΔBH [0.01, 50] is 3 nm or more and 6
It is preferable to form a surface shape of less than nm. Other methods for forming the surface shape include growing the low-melting metal such as Al into islands by sputtering, or protecting the surface by etching with Ar or the like using fine particles dispersed on the surface of the protective film as a mask. There is a method of forming irregularities on the film. However, these two methods have the following disadvantages. In other words, in the method of growing a low melting point metal such as Al into an island shape by using a sputtering method, a material having a low melting point for forming projections generally has low hardness and Young's modulus and is liable to be deformed. Lack of reliability from the viewpoint of In addition, in order to grow the low melting point material into islands having an optimum height and density, an optimum base film is required, and two sputtering processes are added in total, which makes it difficult to control the stability and controllability of the film forming process. become. In addition, in the method of forming irregularities on the protective film by etching with Ar or the like, aggregation of fine particles serving as a mask cannot be avoided, and that portion becomes a projection having a large area. When the head passes over a projection with such a large area, the friction distance becomes long and high frictional heat is generated,
This is undesirable because it gives a large noise to the reproduced signal. On the other hand, in the method of forming a shape on the substrate surface, a desired surface shape can be basically formed by a wet process, so that the cost can be reduced as compared with the dry process. In addition, it is possible to overcome the disadvantages of the above two surface forming methods and to stably mass-produce magnetic recording media. As the substrate, a tempered glass substrate such as aluminosilicate or soda lime is preferable for forming the surface shape, but is not particularly limited as long as the shape can be formed.

The concentration of cobalt and platinum in the constituent elements of the magnetic layer is 80 at.
It is preferable to use a magnetic film having a coercive force of 240 kA / m or more measured with a sample vibration magnetometer at room temperature with 0 kA / m applied. This is due to the excellent electromagnetic conversion characteristics in the high recording density region. However, if the coercive force exceeds 400 kA / m and is too high, the overwrite characteristics are degraded. Therefore, it is preferable that the coercive force of the medium is large enough to be controllable within the overwritable range. An underlayer of Cr-Mo or the like may be further provided between the second underlayer and the magnetic layer.

In order to improve the sliding reliability, a protective layer mainly composed of carbon and having a thickness of 3 to 12 nm is provided on the magnetic layer, and an adsorbable perfluoroalkyl polyether is further formed thereon. It is preferable to provide a lubricating layer having a thickness of 0.5 nm to 3 nm.

A second object of the present invention is to provide a magnetic recording medium,
A drive unit for driving the magnetic recording medium, a magnetic head comprising a recording unit and a reproducing unit, means for moving the magnetic head relative to the magnetic recording medium, a mechanism for ramping the head, and the magnetic head In a magnetic storage device having a signal input means for inputting a signal to the magnetic head and a recording / reproducing signal processing means for reproducing an output signal from the magnetic head, the magnetization directions of the reproducing portions of the magnetic head are relatively changed by an external magnetic field. The present invention as a magnetic recording medium, comprising a magnetoresistive sensor including a plurality of conductive magnetic layers that cause a large change in resistance due to this and a conductive nonmagnetic layer disposed between the conductive magnetic layers. This can be achieved by using the magnetic recording medium described above.

The magneto-resistance effect type magnetic head includes:
It is desirable that the magnetoresistive sensor section is formed between two shield layers made of a soft magnetic material and separated from each other by a distance of 0.06 μm or more and 0.18 μm or less. The distance between the shield layers
If it is larger than 0.18 μm, sufficient reproduction output cannot be obtained in a high linear recording density region exceeding 500 kFCI. If the distance between the shield layers is smaller than 0.06 μm, it is not easy to maintain the insulation between the shield layers and the magnetoresistive sensor. The product Br of the thickness t of the magnetic layer of the magnetic recording medium and the residual magnetic flux density Br measured by applying a magnetic field in the direction of travel of the magnetic head relative to the magnetic recording medium during recording
× t is 3.2 mA (40 gauss / micron) or more and 6.4 mA (80 gauss / micron)
(Micron) or less. Br × t is 3.2 mA (40
If it is smaller than (Gauss / micron), there is a high risk of incorrect information being reproduced due to a decrease in reproduction output due to long-term storage after recording, and if it exceeds 6.4 mA (80 Gauss / micron), Overwriting becomes difficult.

In the magnetic storage device described above, a plurality of conductive magnetic layers which generate a large change in resistance due to a relative change in their magnetization directions by an external magnetic field as a reproducing portion of the magnetic head; Using a magnetoresistive sensor that includes a conductive nonmagnetic layer located between layers,
It is preferable because a signal recorded at the highest linear recording density exceeding FCI can be reproduced stably. Furthermore, the flying height is 13nm or less,
It is desirable to form the magnetic head on a magnetic head slider with a flying surface rail area of 1.4 square millimeters or less and a mass of 2 mg or less. As a result, the probability of collision between the magnetic head and the above-mentioned protrusions can be reduced, and at the same time, the impact in the event of a collision can be reduced, and both high recording density of 11 gigabits per square inch or more and high impact reliability can be achieved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional structural view of an embodiment of a magnetic recording medium according to the present invention. As the substrate 10, a 0.635 mm thick, 2.5-inch type aluminosilicate glass disk substrate whose surface was chemically strengthened was used. After washing this substrate, the following multilayer film was formed thereon using a single-wafer sputtering apparatus (MDP250B) manufactured by Intevac. First, the thickness on the substrate 10
First made of 40nm 65at.% Ni-20at.% Cr-15at.% Zr alloy
Underlayers 11 and 11 ′ were formed on both sides of the substrate. Thereafter, the substrate was heated to a temperature of about 230 ° C. by a lamp heater, and then exposed to an atmosphere of a 99% Ar-1% O 2 mixed gas at a pressure of 5 mTorr (gas flow rate: 21 sccm) for 3.5 seconds. The second underlayers 12 and 12 'made of an.% Cr-20at.% Ti alloy are formed, and a 20 nm thick 66at.% Co-22
forming magnetic layers 13 and 13 'made of at.% Cr-12at.% Pt alloy,
The protective layers 14 and 14 'each having a thickness of 8 nm were formed thereon. afterwards,
The substrate was taken out of the sputtering apparatus, and a lubricant containing perfluoroalkyl polyether as a main component was applied on the protective layer to form lubrication layers 15 and 15 'having a thickness of 2 nm.

The first underlayers 11 and 11 'and the second underlayer
Ar and a gas pressure of 7 mTorr (0.933 Pa) were used for forming 12 and 12 'and magnetic layers 13 and 13'.
And Further, at the time of forming the protective layers 14 and 14 ′ made of carbon, Ar containing nitrogen was used as a discharge gas and 10 mTorr (1.3
3Pa).

The magnetic recording medium thus formed is cut, and the laminated thin film portion is formed into a mortar-like shape in the shape of a mortar by using an ion thinning method in a vertical direction, and the fine structure of the first underlayer is accelerated at an accelerating voltage of 200 kV. As a result of observation with a transmission electron microscope, no crystal grains having a diameter exceeding 5 nm were observed. When a selected area diffraction image was taken, a halo was observed, and it was confirmed that the halo was substantially amorphous.

FIG. 2 shows a load curve obtained from the surface roughness curve. The vertical axis represents the height BH at which the load ratio becomes 50%.
The height based on [50%] (bearing height BH)
The horizontal axis is a logarithmic representation of the load ratio. Here, the difference between the bearing height BH [0.01%] when the load ratio is 0.01% and the bearing height BH [50%] when the load ratio is 50% (= | BH
[0.01%]-BH [50%] |) is defined as ΔBH [0.01, 50].

The surface shape of the substrate used in this embodiment was
As a result of measuring at 8 points on both sides within the range of ~ 31 mm, ΔBH [0.01, 50] at each measurement point was in the range of 4.10 to 5.05 nm, and the average value was 4.59 nm. On the other hand, the surface shape of the above medium formed up to the lubrication layer on the substrate has a radius of 14 to
As a result of measuring at eight places on both sides within the range of 31mm,
When ΔBH [0.01, 50] at each measurement point is in the range of 3.92 to 4.96 nm,
Its average value was 4.53 nm. As described above, the difference between ΔBH [0.01, 50] between the substrate surface and the magnetic recording medium surface is as small as 2% or less, and the surface shape of the medium is substantially determined by the surface shape of the substrate. In this embodiment, by changing the surface shape of the substrate,
A medium having a ΔBH [0.01, 50] of 3 to 6 nm on the medium surface was prepared.

The surface profile was measured using a scanning probe microscope (SPM) Nanoscope II manufactured by Digital Instruments. The measurement range is 10 μm × 10 μm, the number of scan lines is 256, and the scan speed is 1 line / sec.
Using a cantilever with a non-doped syringe probe with a radius of curvature of 20 nm or less, the surface roughness curve was measured by tapping mode. Here, the tapping mode is a method in which a cantilever is vibrated in the vicinity of a resonance frequency (about 50 to 500 kHz) using a piezo vibrator, and scanning is performed while intermittently lightly shaking the surface. The absolute value of the height is a VLSI pattern (Model Number: STS2-18
0, Serial Nuber: 3091-01-105). The height resolution was measured at 0.02 nm. The measured data is filtered before the load curve is calculated.
= 2).

FIG. 3 shows the frictional force and ΔBH [0.01, 50] when the head and the surface of the medium of the present embodiment come into contact at the set flying height of 4 nm.
Shows the relationship. The friction force was measured by detecting the amount of deformation of the parallel spring to which the head was attached with a strain gauge sensor. In order to derive the absolute value of the frictional force, the relationship between the output of the strain gauge and the weight was determined using a weight whose weight was known in advance. The measurement radius position is 22mm from the center of the disc.
The skew angle was 0 °. A negative pressure slider having a pico size (1.2 mm in the longitudinal direction × 1 mm in the lateral direction) was used for the head. Normally, the friction force is correlated with the life of the continuous sliding test, and the life tends to be shorter as the friction force increases. If the frictional force exceeds 25 mN, the slider does not slide stably on the surface of the medium, causing vibration in the pitch direction, making recording and reproduction impossible. The frictional force of the magnetic recording medium manufactured in this example is 12 to 15
mN, which is a range that does not cause problems in sliding reliability and recording / reproducing characteristics.

FIG. 4 shows the relationship between glide count and ΔBH [0.01, 50] when the head flying height is 7 nm. Here, the glide count is a radial position of one side of the disk medium 14 to 31.
It is the number of protrusions that the head contacts within the range of mm. Also,
The head used was a slider with a piezo element bonded to a suspension with a load of 49 mN. The region where the glide count value is 5 or less is almost the range applicable to mass production. The magnetic recording medium of this embodiment falls within this range.
High recording densities of 11 gigabits or more per inch were achieved.

The present invention basically uses a flying type head mainly utilizing an air film. In such a system, in order to ensure high reliability, the center line of the surface roughness of the medium (so-called load ratio is 50%
It is important to control the shape of the surface of the medium that is above the height. In addition, as a result of investigating the sliding reliability of media having various surface shapes, a hard disk drive where the media rotates at a speed of 4000 rpm or more and the head may contact the media surface at a relative speed exceeding 10 m / s In, it became clear that it was necessary to control the surface shape up to a height where the load ratio was about 0.01%. Specifically, as an index representing the surface shape of the medium, the difference ΔBH [0.01,5 between the height at which the load ratio becomes 0.01% and the height at which the load ratio becomes 50%
0], and by controlling the shape of the medium surface such that ΔBH [0.01, 50] is in the range of 3 to 6 nm, high reliability can be obtained.

The thickness t of the magnetic layer of the medium manufactured in this embodiment
Magnetic flux density measured by applying a magnetic field in the direction of travel of the magnetic head relative to the magnetic recording medium during and after recording
The product Br × t with Br was 4.8 mA (60 gauss / micron) and the holding power was 260 kA / m. Using this medium, we evaluated the ratio SLF / Nd between the output amplitude (0-p value) SLF of the isolated reproduction wave and the integrated medium noise Nd when a signal with a recording density of 400 kFCI was recorded. The value was obtained. Here, as the magnetic head, a magnetic head composed of a spin-valve type reproducing element described in Example 7 with a shield gap length Gs of 0.18 μm and an electromagnetic induction type writing element with a gap length of 0.25 μm was used. Was set to 15 nm.

Comparative Example 1 A magnetic recording medium prepared in the same manner as in Example 1 except that ΔBH [0.01, 50] on the medium surface was 1 to 2.6 nm was used as Comparative Example 1. FIG. 3 plots the relationship between the frictional force of the medium of this comparative example and ΔBH [0.01, 50]. While the frictional force of the medium of Example 1 was 12 to 15 mN, the frictional force of the medium of this comparative example was 46 to 52 mN, which not only deteriorated the sliding reliability but also prevented stable recording and reproduction. It is possible. Therefore, in this comparative example, it is difficult to achieve a high recording density of 11 gigabits per inch or more.

<Comparative Example 2> The Δ
A magnetic recording medium prepared under the same conditions as above except that BH [0.01, 50] was 6.3 to 9.1 nm was used as Comparative Example 2.

As shown in FIG. 3, the frictional force of Comparative Example 2 was 8
1313 mN, which is equal to or less than that of the first embodiment. For this reason, problems do not easily occur in sliding reliability and stable recording / reproducing characteristics. However, as shown in FIG. 4, as ΔBH [0.01, 50] increases, the glide count sharply increases, so that the probability of head crash increases, which is a problem in sliding reliability. Therefore, in this comparative example, it is difficult to achieve a high recording density of 11 gigabits per inch or more.

<Embodiment 2> As Embodiment 2, a magnetic recording medium prepared in the same manner as in Embodiment 1 except that ΔBH [0.01, 0.8] on the medium surface is in the range of 0.22 to 3.84 nm, and the other conditions are the same as above. Was prepared. Here, ΔBH [0.01, 0.8] is as shown in FIG. 2, and the bearing height BH [0. 0 when the load ratio is 0.01%.
01%] and bearing height BH [0.8%] when the load ratio is 0.8%
Difference (= | BH [0.01%]-BH [0.8%] |). Also, as a result of measuring ΔBH [0.01, 50] of the medium of Example 2,
It was in the range of 4.42 to 5.38 nm.

FIG. 5 shows the time until a crash when the head and the medium keep contacting each other at the set flying height of 4 nm and ΔBH [0.0
1, 0.8]. When ΔBH [0.01, 0.8] exceeds 3 nm, it can be seen that as ΔBH [0.01, 0.8] increases, the time to crash decreases. ΔBH [0.01,
0.8] means that the height variation at the top of the surface roughness is large, so it is considered that the plastic deformation occurs from the high part due to the variation and wear occurs. At a high recording density of 11 gigabits per inch or more to be achieved by the present invention, the thickness of the protective film provided on the magnetic layer is reduced.
Since the thickness is very thin, less than 8 nm, ΔBH [0.
When [01, 0.8] exceeds 3 nm, the abrasion is too great and sufficient sliding reliability cannot be ensured. Therefore, ΔBH
It is appropriate that [0.01, 0.8] is not less than 0.2 nm and not more than 30 nm.

<Embodiment 3> As Embodiment 3, a magnetic recording medium manufactured under the same conditions as above in Embodiment 1 except that the thickness of the first underlayer is in the range of 0 to 90 nm, and Two types of magnetic recording media were manufactured under the same conditions as above except that the thickness of the second underlayer was in the range of 0 to 100 nm. FIG. 6 shows the relationship between the time until the head crashes and the thickness of the first underlayer when the head and the medium continue to contact each other at the set flying height of 4 nm. FIG. 7 shows the relationship between the glide count and the thickness of the second underlayer when the head flying height is 7 nm.

FIG. 6 shows that no crash can be confirmed even if 250 hours have passed when the thickness of the first underlayer is 20 nm or more.
On the other hand, if it is less than 20 nm, the time to crash is short,
The thickness is less than half the thickness compared to 20 nm or more, and the interface with high frequency of dynamic contact between the head and the medium has insufficient sliding resistance. In general, the sputtering apparatus used to form each layer of the medium is not limited to the film forming apparatus manufactured by Intevac Corporation used in the present embodiment. And the consumption of the target increases, and the cost increases. Also, in order to reduce mass production tact and reduce the frequency of target replacement,
It is necessary to add a film forming chamber, and extra cost is required. Therefore, the thickness of the first underlayer is suitably 80 nm or less.

As shown in FIG. 7, the glide count is 4 or less when the thickness of the second underlayer is 60 nm or less, whereas the glide count is significantly increased when the thickness exceeds 60 nm.
This is a problem specific to crystalline materials as described above. When the film thickness is large, it is easy to grow abnormally in the direction perpendicular to the medium surface, and when the film thickness exceeds 60 nm, it comes into contact with the head flying at a flying height of 7 nm. Then it can be estimated. On the other hand, a medium with a second underlayer thickness of 2 nm has a coercive force of 120 kA / m, which is required at a high recording density of 11 gigabits per inch or more.
It is far below 0kA / m. The thickness of the second underlayer is 3
nm or more, preferably 8 nm or more.

<Embodiment 4> FIG. 8 is a sectional structural view of an embodiment of a magnetic recording medium according to the present invention. As the substrate 70, a 0.635 mm-thick, 2.5-inch aluminosilicate glass substrate whose surface was chemically strengthened was used. After washing this substrate, the following multilayer film was formed thereon using a single-wafer sputtering apparatus (MDP250B) manufactured by Intevac. First, the temperature of the substrate is heated to about 230 ° C. by a lamp heater, and then the thickness of 0 to 10
Underlayers 71 and 71 ′ made of 0 nm 80 at.% Cr-20 at.% Ti alloy
Was formed on both sides of the substrate. On top of that, 66at.% Of 20nm thickness
Magnetic layers 72 and 72 'made of a Co-22at.% Cr-12at.% Pt alloy were formed, and protective layers 73 and 73' having a thickness of 8 nm were formed thereon. Thereafter, the substrate was taken out of the sputtering apparatus, and a lubricant containing perfluoroalkyl polyether as a main component was applied on the protective layer to produce a magnetic recording medium in which lubricating layers 74 and 74 'having a thickness of 2 nm were formed. Here, the surface shape of the medium was measured using the AFM under the same conditions as in Example 1, and as a result, the radius was 14 to 31 mm.
BBH [0.01,
50] was 3.20 to 5.61 nm.

FIG. 9 shows the relationship between the glide count at a flying height of 7 nm and the thickness of the underlayer. The glide count is less than 4 when the thickness of the underlayer is 50 nm or less,
Above 0 nm, glide count increases significantly. This is a problem peculiar to crystalline as described above. As the film thickness increases, abnormal growth tends to occur in the direction perpendicular to the medium surface.
If the thickness exceeds 60 nm, it can be estimated that the head comes in contact with the flying head at a flying height of 7 nm. As described above, even if a substantially amorphous underlayer is not formed between the substrate and the crystalline underlayer, if the thickness of the crystalline underlayer is 50 nm or less, 1
The required low levitation and sliding resistance can be secured at a high recording density of 11 gigabits per inch or more.

<Embodiment 5> In the load ratio shown in FIG. 2, the difference between the bearing height BH [1%] when the load ratio is 1% and the bearing height BH [50%] when the load ratio is 50% is shown. Defined as y. Also, bearing height BH [15%] when the load ratio is 15%
And the bearing height BH [50%] at a load ratio of 50%
Is defined.

In the fifth embodiment, the medium y is 0.81 to 4.35 nm.
Thus, a surface shape having x in the range of 0.11 to 1.66 nm was produced by changing the surface shape of the substrate. Except for the above surface shape, it was manufactured under the same conditions as in Example 4. FIG. 10 shows that the medium that did not crash for 2000 hours or more when the head and the medium continued to contact at the set flying height of 4 nm was marked with a circle.
A medium that crashed in less than 500 hours was marked with △, a medium that crashed in less than 500 hours was marked with x, y was set on the vertical axis, and x was set on the horizontal axis
It is a mapping. In FIG. 10, in an area smaller than a straight line connecting point (0.1, 1.6) and point (1, 3) where y is represented by coordinates (x, y), a crash occurs in less than 500 hours. The straight line connecting point (0.1, 1.6) and point (1, 3) is the height x near the center of the roughness (load ratio 15%) and near the middle (load ratio).
1%), which indicates that there is a necessary y (limit height) for wear characteristics for any x. This critical height is the factor necessary for the surface design to ensure low levitation and high reliability. Therefore, if the height is less than the limit height, the head cannot be stably supported for a long time, and it is considered that a crash occurs. X is 1 nm
Crashes occur in less than 2,000 hours for the region exceeding y and the region where y exceeds 4 nm. If the surface of the medium gradually starts to wear under the friction environment between the head and the medium, the vicinity of the center of the roughness may also be a contact target. At that time, the larger the value of x, the larger the contact area at a higher position, and the greater the frictional force. In the region where y is more than the straight line connecting point (0.1, 1.6) and point (1, 3) and x exceeds 1 nm, the frictional force increased during the long-term continuous contact test, and crashed in less than 2000 hours It is inferred. On the other hand, in the region where y exceeds 4 nm,
It is considered that the roughness was so large that it severely interfered with the head, so that wear could not be suppressed, and that it crashed in less than 2000 hours.

As described above, the point represented by the coordinates (x, y) in FIG. 10 is the point (0.1, 1.6) and the point (1, 3) on the xy plane.
And a line connecting points (1, 3) and (1, 4)
A line segment connecting point (1, 4) and point (0.1, 4) and point (0.
In the area (A) surrounded by the line connecting the points (1, 4) and the points (0.1, 1.6), a sliding resistance of 2000 hours or more can be secured, and a high recording density of 20 gigabits or more per inch can be obtained. Necessary low levitation and sliding resistance can be secured. Sufficient characteristics were obtained even without an underlayer consisting of an amorphous layer. Here, the arithmetic average roughness (Ra) within the area (A)
Was measured by AFM under the same conditions as in Example 1.
0.21 to 0.69 nm.

<Embodiment 6> In FIG. 10, the surface roughness of the medium is in the region (A), y is 2.91 to 3.13 nm, and x is 0.2.
A magnetic recording medium having a thickness of 42 to 0.50 nm and having the same conditions as in Example 1 having an underlayer made of amorphous except for the surface shape was produced as Example 6. Here, the arithmetic average roughness (Ra) of Example 6 was 0.39 to 0.48 nm.

As a result of a continuous contact test of the medium and the head at the set flying height of 4 nm, it was confirmed that the medium and the head continued to operate without crash for more than 3000 hours, and the low flying performance required at a high recording density of 40 gigabits per inch or more was obtained. And the sliding resistance was secured.

<Embodiment 7> The magnetic recording medium 91 described in Embodiments 1 to 6 and a drive unit 92 for driving the magnetic recording medium
A magnetic head 93 comprising a recording unit and a reproducing unit; and means 94 for moving the magnetic head relative to the magnetic recording medium.
Signal input means to the magnetic head, and recording / reproducing signal processing means 95 for reproducing an output signal from the magnetic head.
FIG. 11 shows a magnetic storage device having a mechanical unit 96 that is retracted during unloading.

The reproducing section of the magnetic head is constituted by a magnetoresistive head. FIG. 12 is a schematic perspective view showing the structure of the magnetic head. This head is a substrate
This is a composite head having both an electromagnetic induction type head for recording and a magnetoresistive head for reproduction formed on 401. The recording head has an upper recording magnetic pole 403 sandwiching a coil 402.
And a lower recording magnetic pole / upper shield layer 404. The gap length between the recording magnetic poles was 0.27 μm. Further, copper having a thickness of 3 μm was used for the coil. The reproducing head comprises a magnetoresistive sensor 405 and electrode patterns 406 at both ends of the magnetoresistive sensor. The magnetoresistive sensor is sandwiched between a lower recording magnetic pole / upper shield layer 404 and a lower shield layer 407. The distance between the two shield layers is
It was set to 0.15 μm. In this figure, the gap layer between the recording magnetic poles and the gap layer between the shield layer and the magnetoresistive sensor are omitted.

FIG. 13 shows a sectional structure of the magnetoresistive sensor. The signal detection area 500 of the magnetic sensor is composed of a plurality of conductive magnetic layers that generate a large resistance change when their magnetization directions change relative to each other due to an external magnetic field, and a conductive layer disposed between the conductive magnetic layers. It is constituted by a magnetoresistive sensor (spin-valve type reproducing element) including a nonmagnetic layer. The structure of this magnetic sensor is such that Ta
It has a structure in which a buffer layer 502, a first magnetic layer 503, an intermediate layer 504 made of copper, a second magnetic layer 505, and an antiferromagnetic layer 506 made of an Fe-50at.% Mn alloy are sequentially formed. A Ni-20at.% Fe alloy was used for the first magnetic layer, and cobalt was used for the second magnetic layer. The magnetization of the second magnetic layer is fixed in one direction by the exchange magnetic field from the antiferromagnetic layer. On the other hand, the first magnetic layer and the first magnetic layer which are in contact with each other via the non-magnetic layer.
Since the direction of magnetization of the magnetic layer changes due to the leakage magnetic field from the magnetic recording medium, a resistance change occurs.

At both ends of the signal detection area, there are tapered portions 507 which are formed into a tapered shape. The tapered portion includes a permanent magnet layer 508 for converting the first magnetic layer into a single magnetic domain, and a pair of electrodes 406 formed thereon for extracting a signal.
Consists of The permanent magnet layer must have a large coercive force and the magnetization direction must not change easily, and a Co-Cr-Pt alloy was used.

By combining the magnetic recording medium of the present invention described in Examples 1 to 5 with the above-described head shown in FIG.
The magnetic storage device shown in FIG. 11 was configured. When using any of the above media, the magnetic storage device configured as described above could achieve a recording density of 11 gigabits per square inch or more.

In this embodiment, the minimum flying height is 10 nm, the area of the flying surface rail is 1.4 square millimeters or less, and the mass is 2 m.
A magnetic head having a magnetoresistive magnetic head formed on a magnetic head slider of g or less was used. By setting the area of the slider's air bearing surface rail to 1.4 mm2 or less and the mass to 2 mg or less, the impact reliability can be improved. As a result, it is possible to achieve both high recording density and high impact resistance.
With a recording density of gigabit or more, a mean time between failures (MTBF) of 300,000 hours or more was realized.

<Embodiment 8> FIG. 1 is a sectional structural view of a magnetic recording medium according to an embodiment of the present invention. As the substrate 10, a 0.635 mm thick, 2.5-inch type aluminosilicate glass disk substrate whose surface was chemically strengthened was used. After washing this substrate, the following multilayer film was formed thereon using a single-wafer sputtering apparatus (MDP250B) manufactured by Intevac. First, the thickness on the substrate 10
40 nm 83at.% Ni-17at.% P alloy first underlayer 11
And 11 'were formed on both sides of the substrate. After that, the temperature of the substrate is heated to about 230 ° C. by a lamp heater, and the thickness is 30 n.
Second underlayers 12 and 1 made of 80 at.% Cr-20 at.% Ti alloy
2 'is formed thereon, and a 20 nm thick 66at.% Co-22at.% Cr-
Magnetic layers 13 and 13 'made of a 12 at.% Pt alloy were formed, and protective layers 14 and 14' having a thickness of 8 nm were formed thereon. Thereafter, the substrate was taken out of the sputtering apparatus, and a lubricant containing perfluoroalkyl polyether as a main component was applied on the protective layer to form lubricant layers 15 and 15 'having a thickness of 2 nm.

The first underlayers 11 and 11 'and the second underlayer
Ar and a gas pressure of 7 mTorr (0.933 Pa) were used for forming 12 and 12 'and magnetic layers 13 and 13'.
And Further, at the time of forming the protective layers 14 and 14 ′ made of carbon, Ar containing nitrogen was used as a discharge gas and 10 mTorr (1.3
3Pa).

The magnetic recording medium thus formed is cut, and the laminated thin film portion is formed into a mortar-like shape by an ion thinning method so as to be vertically thinner from a direction perpendicular to the film surface, and the fine structure of the first underlayer is accelerated at an accelerating voltage of 200 kV. As a result of observation with a transmission electron microscope, no crystal grains having a diameter exceeding 5 nm were observed. When a selected area diffraction image was taken, a halo was observed, and it was confirmed that the halo was substantially amorphous.

The surface shape of this embodiment is set to a radius of 14 to 31 mm.
As a result of measurement at eight locations on both sides within the range, ΔBH [0.01, 50] at each measurement point was in the range of 4.22 to 5.29 nm.

As described above, even in the first underlayer made of the Ni—P alloy, the first underlayer is substantially amorphous,
A magnetic recording medium having a BH [0.01, 50] of 3 nm or more and 6 nm or less was produced.

The ratio SLF / Nd of the output amplitude (0-p value) SLF of the isolated reproduction wave of the medium manufactured in this embodiment and the integrated medium noise Nd when a signal having a recording density of 400 kFCI was recorded was evaluated. , A high value of 26.4 dB was obtained. Here, as the magnetic head, a magnetic head composed of the spin-valve reproducing element described in Example 4 in which the shield gap length Gs was 0.18 μm and an electromagnetic induction type writing element having a gap length of 0.25 μm was used. Was set to 15 nm.

[0062]

According to the magnetic recording medium of the present invention, a magnetic head and a magnetic recording medium which are generated in an extremely low flying environment while a magnetic disk drive is operating while maintaining low noise characteristics important for realizing high recording density. The contact damage of the contact is suppressed, and high sliding reliability can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a magnetic recording medium of the present invention.

FIG. 2 is an example of a load curve of a magnetic recording medium.

FIG. 3 is a diagram showing a relationship between a frictional force and a surface shape.

FIG. 4 is a diagram showing a relationship between glide count and surface shape.

FIG. 5 is a diagram showing a relationship between a time until a crash and a surface shape in a sliding test.

FIG. 6 is a diagram showing a relationship between a time until a crash and a first underlayer thickness in a sliding test.

FIG. 7 is a diagram showing a relationship between a glide count and a second underlayer thickness.

FIG. 8 is a schematic sectional view showing an example of the magnetic recording medium of the present invention.

FIG. 9 is a diagram showing the relationship between glide count and the thickness of a crystalline underlayer when there is no amorphous underlayer.

FIG. 10 is a map diagram showing a relationship between a time until a crash and a surface shape in a sliding test.

FIG. 11 is a schematic view of a magnetic disk drive according to the present invention.

FIG. 12 is a schematic diagram showing an example of a sectional structure of a magnetoresistive sensor of a magnetic head in the magnetic disk drive of the present invention.

FIG. 13 is a schematic sectional view showing an example of a sectional structure of a magnetoresistive sensor of a magnetic head in the magnetic disk drive of the present invention.

[Explanation of symbols]

10 ... substrate, 11,11 '... first underlayer, 12,12' ... second underlayer, 13,13 '... magnetic layer, 14,14' ... protective layer, 15,15 '... lubricant layer, 70: substrate, 71, 71 ': underlayer, 72, 72': magnetic layer, 73, 7
3 ': protective layer, 74, 74': lubricating layer, 91: magnetic recording medium, 92:
Drive section for driving the magnetic recording medium, 93 ... magnetic head, 94 ...
Means for moving the magnetic head relative to the magnetic recording medium, 95: recording / reproducing signal processing means, 96: a mechanical unit for retreating during unloading, 401: base, 402: coil, 403: upper recording magnetic pole, 404: lower recording Magnetic pole and upper shield layer, 405: magnetoresistive sensor, 406: electrode pattern, 407: lower shield layer, 500: signal detection area of magnetic sensor, 501: gap layer, 502: Ta buffer layer, 503: first magnetic layer Reference numeral 504 denotes an intermediate layer 505 denotes a second magnetic layer 506 denotes an antiferromagnetic layer 507 denotes a tapered portion 508 denotes a permanent magnet layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Rinka Goda 2880 Kozu, Kozuhara-shi, Kanagawa Prefecture, Ltd.Storage Systems Division, Hitachi, Ltd. Within Storage System Division (72) Inventor Akira Kato 2880 Kozu, Odawara-shi, Kanagawa Prefecture F-term (reference) 5D006 BB01 BB07 CA01 CA05 CA06 DA03 in Hitachi, Ltd. Storage System Division

Claims (11)

[Claims] 1. A magnetic recording medium in which a magnetic alloy layer containing Co as a main component, a protective layer, and a lubricating layer are formed in this order on a substrate via an underlayer, wherein the underlayer is a substantially amorphous layer. A plurality of underlayers including a structure in which a first underlayer made of and a second underlayer made of a crystalline layer are stacked in this order,
Further, in the load curve obtained from the surface roughness curve of the magnetic recording medium, the difference ΔBH [between the height BH [0.01%] at which the load ratio becomes 0.01% and the height BH [50%] at which the load ratio becomes 50%. 0.01, 50]
(= | BH [0.01%]-BH [50%] |) is 3 nm or more and 6 nm or less. 2. A load curve obtained from a surface roughness curve of a magnetic recording medium, wherein a height BH [0.01] at which a load ratio becomes 0.01%.
%] And height BH [0.8%] at which the load ratio becomes 0.8% ΔBH [0.01,
2. The magnetic recording medium according to claim 1, wherein 0.8] (= | BH [0.01%]-BH [0.8%] |) is not less than 0.2 nm and not more than 3 nm. 3. The first underlayer is made of a substantially amorphous alloy containing Co or Ni as a main component, and the second underlayer is made of Cr or an alloy containing Cr as a main component. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is formed. 4. The semiconductor device according to claim 1, wherein said first underlayer has a thickness of 20 nm to 80 nm, and said second underlayer has a thickness of 3 nm to 60 nm.
4. The magnetic recording medium according to claim 1, wherein: 5. A magnetic recording medium comprising a magnetic alloy layer containing Co as a main component, a protective layer, and a lubricating layer formed in this order on a substrate with an underlayer interposed therebetween, wherein the underlayer has a thickness of 3 nm or more and 50 nm or less. And a height BH [0.01%] at which the load ratio is 0.01% and a height BH at which the load ratio is 50% in the load curve obtained from the surface roughness curve of the magnetic recording medium. [50%] difference ΔBH [0.01, 50] (= | BH [0.01%]-BH [50
%] |) Is 3 nm or more and 6 nm or less. 6. A load curve obtained from a surface roughness curve of a magnetic recording medium, wherein a height BH [0.01] at which a load ratio is 0.01%.
%] And height BH [0.8%] at which the load ratio becomes 0.8% ΔBH [0.01,
0.8] (= | BH [0.01%]-BH [0.8%] |) is 0.2nm or more, 3nm
The magnetic recording medium according to claim 5, wherein: 7. A magnetic recording medium in which a magnetic alloy layer, a protective layer, and a lubricating layer are formed in this order on a substrate with an underlayer interposed therebetween.
In the load curve obtained from the surface roughness curve of the magnetic recording medium, the height BH [1%] at which the load ratio is 1% and the load ratio are 50%
The difference between the heights BH [50%] is y (= | BH [1%]-BH [50%] |), and the height BH [15%] at which the load ratio is 15% and the load ratio are 50 %
X (= | BH [15%]-BH [50%] |)
Then, the point represented by the coordinates (x, y) is a line segment connecting the point (0.1, 1.6) and the point (1, 3) on the xy plane, and the point (1, 3)
Segment connecting point (1, 4) and point (1, 4) and point (0.1, 4)
The magnetic recording medium is located within an area surrounded by a line segment connecting the points (0.1, 4) and (0.1, 1.6). 8. A magnetic recording medium in which a magnetic alloy layer, a protective layer, and a lubricating layer are formed in this order on a substrate via an underlayer.
The magnetic recording medium according to claim 7, wherein an arithmetic average roughness (Ra) obtained from a surface roughness curve of the magnetic recording medium is 0.2 nm or more and 0.7 nm or less. 9. A magnetic recording medium in which a magnetic alloy layer containing Co as a main component, a protective layer, and a lubricating layer are formed in this order on a substrate via an underlayer, wherein the underlayer is a substantially amorphous layer. 9. The magnetic layer according to claim 7, wherein the magnetic layer comprises a plurality of underlayers including a structure in which a first underlayer made of and a second underlayer made of a crystalline layer are laminated in this order. recoding media. 10. In a load curve obtained from a surface roughness curve of a substrate, a difference ΔBH [between a height BH [0.01%] at which the load ratio becomes 0.01% and a height BH [50%] at which the load ratio becomes 50%. 0.01, 50] (=
6. The magnetic recording medium according to claim 1, wherein | BH [0.01%]-BH [50%] |) is 3 nm or more and 6 nm or less. 11. A magnetic recording medium, a driving unit for driving the magnetic recording medium, a magnetic head including a recording unit and a reproducing unit,
Means for moving the magnetic head relative to the magnetic recording medium, a mechanism for ramping the magnetic head, signal input means for the magnetic head, and recording for reproducing an output signal from the magnetic head In a magnetic disk drive having reproduction signal processing means, a plurality of conductive magnetic layers in which a reproducing portion of the magnetic head causes a large resistance change due to a relative change in magnetization direction of each other due to an external magnetic field; A magnetic disk drive comprising a magnetoresistive sensor including a conductive nonmagnetic layer disposed between magnetic layers, and wherein the magnetic recording medium is the magnetic recording medium according to any one of claims 1 to 10.