JPH05205258A - Magnetic recording medium and magnetic recording device - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium achieving a high-density recording by forming, in one direction, each of a texture in circumferential direction and that in radius direction on the surface of a non-magnetic disk substrate. CONSTITUTION:Non-magnetic plating layers 12 and 12' made of NiP, etc., are formed on both surfaces of a magnetic disk substrate 11 which is made of Al-Mg alloy, ceramic, etc., and then metal ground films 13 and 13' of metals such as Cr and Mo or their alloys are formed on the surface. Furthermore, metal magnetic layers 14 and 14' made of CoNi, CoCr, etc., are formed on the ground films 13 and 13' and then non-magnetic protective films 15 and 15' made of carbon, boron, etc., are formed on them. Then, an abrasive 24 is supplied by pressing an abrasion tape 22 of a tape polishing magazine with a contact roll 24 while rotating a disk substrate 21 and a texture 25 in radius direction and a texture 26 in circumferential direction are formed on the surface of the substrate 21, thus obtaining a magnetic recording medium which has uniform magnetic recording characteristics and achieves high-density recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and a magnetic recording device, and more particularly to a thin film type recording medium suitable for high density magnetic recording and a magnetic recording device using the same.

[0002]

2. Description of the Related Art With the recent trend toward miniaturization and high speed of electronic computers, there has been a strong demand for large capacity and high speed access of magnetic disk devices and other external storage devices. Particularly, the magnetic disk recording device is a storage device suitable for high-density and high-speed recording, and the demand thereof is further increasing.

As a magnetic recording medium used in a magnetic disk device, a coating type recording medium in which a powder of an oxide magnetic material is coated on a disk substrate and a thin film type recording medium in which a thin film of a metal magnetic material is deposited on a substrate are used. The medium is known. This thin film type recording medium is suitable for higher density recording because the density of the magnetic substance in the recording film is higher than that of the coating type recording medium.

Aluminum alloy, glass, organic resin, ceramics, etc. are generally used as the disk substrate material of the thin film type recording medium. Further, in order to improve the surface hardness and magnetic characteristics of the disk substrate, for example, an anodic oxide film or a Ni—P layer having a thickness of about 15 μm may be formed by a plating method or the like. On such a substrate surface, US Pat.
35840, JP-A-61-29418, JP-A-62.
There are cases where fine grooves are formed in the substantially circumferential direction as described in JP-A-146434 and JP-A-63-121123. This fine groove is generally called a texture and is formed by cutting the disk surface in a substantially circumferential direction using abrasive grains having a grain size of 1 to several μm. This texture reduces the effective contact area between the magnetic head and the medium when the rotation is stopped, and reduces the coefficient of friction between the head and the medium. Also,
Depending on the shape and size of this texture, the effect of suppressing head adhesion at the start of rotation has been recognized. Further, when this texture is provided, by optimizing the size of the texture, the film thickness of the underlayer film, and the film forming conditions, the magnetic characteristics of the magnetic film in the substantially circumferential direction, for example, the coercive force Hc.
Alternatively, the values of the squareness ratio S and the residual magnetization amount Mr are improved as compared with a medium having no texture, and as a result, the effect of improving the resolution and S / N during recording / reproduction may be recognized. Furthermore, the magnetic anisotropy in the substantially circumferential direction of the medium may become non-uniform and the reproduction output may fluctuate depending on the conditions at the time of manufacturing the medium, for example, the heating temperature and the transportation method.
By optimizing the composition of the underlayer film and the magnetic film, the film forming conditions, etc., the magnetic anisotropy in the substantially circumferential direction is made uniform by the texture,
As a result, the effect of suppressing fluctuations in the recording / reproducing output (hereinafter abbreviated as modulation) was also recognized.

[0005]

The above-mentioned conventional substantially circumferential texture is effective for improving the sliding resistance and recording / reproducing characteristics of the thin film type recording medium, but the effect is microscopic on the texture surface. It varies greatly depending on the shape. Therefore, in order to form a medium having a uniform magnetic property in the surface with good reproducibility, it is necessary to form a microscopic shape of the texture uniformly in the surface of the medium with good reproducibility. However, since the texture on the metal substrate is usually formed by using abrasive grains having a grain size of 1 to several μm, it is difficult to uniformly control the fine surface roughness and pitch of less than 1 μm. As a result, there has been a problem that the coefficient of friction between the head and the medium at the time of rotation start and the recording / reproducing characteristics fluctuate within the disk surface or between lots.

In order to perform higher density recording / reproducing in the future, it is necessary to make the width of the recording track smaller than that of the present. In that case, the non-uniformity of the texture shape in the radial direction of the disc has a greater effect on the fluctuation of the recording / reproducing signal than in the past. In particular, there is a problem that the conventional texture cannot be adopted when the uniformity of the recording / reproducing characteristics in the radial direction of the disk is strictly required like the positioning servo signal.

On the other hand, in order to improve the recording density, the gap between the magnetic head and the recording medium at the time of recording / reproducing (hereinafter abbreviated as spacing) is made as narrow as possible to form a steep magnetic field distribution in the medium. It is important to. However, it has been found that in a disk substrate that has been subjected to a texture treatment in a substantially circumferential direction, when the substrate is rotated with a narrow spacing, the magnetic head and the medium come into contact with each other more frequently than a disk substrate without a texture. It was It was found that this is because a fine protrusion is inevitably formed on the surface of the disk by the texturing, and this comes into contact with the magnetic head when the spacing is lowered. In order to reduce the frequency of contact between the head and the medium and improve the reliability of the magnetic disk device, the protrusions on the disk substrate surface should be removed by a polishing process (described in JP-A-1-162229) or the texture itself. The texture forming conditions may be controlled so as to reduce the size of the irregularities, but in this case, the contact area between the magnetic head and the medium increases, and head adhesion at the start of rotation cannot be avoided. Also, Japanese Patent Laid-Open No. 1-2732
No. 18 discloses a method of reducing the dynamic friction coefficient by forming textures in the substantially circumferential direction intersecting with each other. In this case, the magnetic properties of the magnetic film in the substantially circumferential direction are compared with the conventional texture. It could not be made sufficiently higher than that of the medium in which was formed, and the suppression of modulation was insufficient.

Further, in the conventional thin film type recording medium, the resolution and S / N at the time of recording / reproducing are still insufficient, and in order to improve the performance of the magnetic disk device from the present, a medium having more excellent characteristics was developed. There is a strong demand to do it.

A first object of the present invention is to provide a magnetic recording medium having uniform magnetic recording characteristics in the medium surface and capable of high density recording. The second object is to provide a large capacity and highly reliable magnetic recording device using such a medium.

[0010]

The above object can be achieved by forming textures in the circumferential direction and the radial direction in a mixed manner on the surface of the disk substrate. Here, a texture in which the angle between the texture and a radial straight line connecting the center of the disc and the texture is less than ± 45 degrees is defined as a texture in the radial direction. A texture in which the angle between the straight line perpendicular to the radial straight line and the texture is ± 45 degrees or less is defined as the circumferential texture. The angle is measured counterclockwise with the straight line as the starting line.

In order to form the above-mentioned texture in a mixed manner on the surface of the disk substrate, both a step of polishing in the circumferential direction of the disk and a step of polishing in the radial direction of the disk are required. Also, in order to prevent the texture formed in the former stage from being lost in the latter stage texture forming process, the conditions such as the type of abrasive grains, grain size, polishing pressure, polishing time and polishing liquid should be optimized during texture formation. You need to control the value. That is, it is necessary to control the amount of polishing the disk surface to be small, for example, by shortening the polishing particle size and the polishing pressure and shortening the polishing time.

The texture in the substantially circumferential direction is similar to the conventional one.
It can be formed by rotating the disc at a high speed while pressing a polishing tape or buff from both sides of the disc in the presence of an abrasive. At this time, polishing tape, etc.
When the disk is vibrated at a speed lower than the rotational peripheral speed in the radial direction, the direction of the texture changes from the circumferential direction to the radial direction. The texture in the circumferential direction of the present invention includes a conventional texture in the substantially circumferential direction and a texture formed by vibrating at a low speed. As the moving speed of the polishing tape or the like increases, the direction of the texture becomes more radial.
In addition, the form of the texture can be changed by changing the amplitude and frequency of vibration of the polishing tape or the like. On the other hand, the radial texture can be formed by making the moving speed of the polishing tape or the like higher than the peripheral speed of rotation.

If the texture is formed such that the size of the unevenness of the texture in the circumferential direction is substantially larger than the size of the unevenness of the texture in the radial direction, the recording / reproducing characteristics are improved and the modulation is reduced. preferable.

Here, the center line average roughness Ra and the maximum height Rmax are used as an index showing the size of the unevenness of the texture.
To use. In order to obtain good results in terms of fluctuations in recording / reproducing characteristics, spacing between head media, and head adhesion at startup, the Ra value range is 0.5 nm or more and less than 10 nm, and the Rmax value range is 5 nm or more and 100 nm. Less than is preferred. Further, in order to record at high density, for example, 0.
When operating the head and the medium with an extremely narrow spacing of 15 μm or less, a medium with particularly high sliding resistance is required. In this case, the Ra value range of the medium is 0.
The range of 5 nm or more and less than 5 nm and the Rmax value is preferably 5 nm or more and less than 50 nm. Note that the use of "center line average roughness" and "maximum height" in this specification is as follows.
It conforms to the definition stipulated in Japanese Industrial Standards (JIS-B0601).

Further, Cr, Mo,
The magnetic characteristics can be improved by forming an underlayer containing W or an alloy containing these as the main components in a thickness of 10 to 500 nm. Furthermore, Co or Fe, or Ni
By forming a magnetic layer having a thickness of 10 to 100 nm as a main component, a carbon having a thickness of 10 to 50 nm as a protective layer, and further providing a lubricating layer of 1 to 20 nm of an adsorbent perfluoroalkyl polyether or the like, A magnetic recording medium capable of high density recording in the plane is obtained. In addition, as an underlayer, Cr, Mo, W with Ti, Ta, Pt,
An alloy containing any one of Pd, Si, Fe, and V is used, and Cr, Mo, W, Zr, Ta, and
It is preferable to use an alloy to which at least one of Nb, Al, Si and Pt is added, because the recording / reproducing characteristics and corrosion resistance of the medium are further improved. In particular, the magnetic substance forming the magnetic layer is CoNi, CoCr, CoFe, CoMo,
Good properties are recognized when the alloy is CoW, CoPt, CoRe, or the like. In addition, when particularly good corrosion resistance and magnetic properties are required, CoNiZr, CoCrPt, CoCrTa, CoN are used as the magnetic material for forming the magnetic film.
It is desirable to use an alloy containing iCr as a main component. Further, as a protective layer, carbides such as WC and WMoC, Z
It is preferable to use a nitride such as rNbN, Si ₃ N ₄ or the like, an oxide such as SiO ₂ , ZrO ₂ , or B, B ₄ C, MoS ₂ , Rh or the like because the sliding resistance and the corrosion resistance can be improved. For the disk substrate, Al-Mg alloy, chemically strengthened glass, or organic resin can be used, and a non-magnetic plating layer made of NiP, NiWP, NiV or the like formed on these substrates is used. It is also possible. Furthermore, by combining a magnetic recording medium with a magnetic head having a track width of 10 μm or less, it is possible to provide a magnetic recording device having a large capacity and high reliability.

[0016]

As a result of intensive studies on the relationship between the fine surface shape of the disk substrate, the magnetic recording characteristics, and the head flying property, the present inventors have found that the object is to mix textures in the circumferential and radial directions on the surface of the disk substrate. We obtained the knowledge that it can be achieved by doing.

When the texture is formed on the surface of the disk substrate in a mixed manner in the circumferential direction and the radial direction, the magnetic head-medium at the time of stopping is different from the conventional medium in which the texture having the same unevenness is formed only in the substantially circumferential direction. The contact area between
As a result, head adhesion at the start of rotation is suppressed. Therefore, head adhesion can be suppressed even when a texture having extremely small unevenness is used as compared with the conventional medium in which the texture is formed only in the substantially circumferential direction. Furthermore, if the texture irregularities are made smaller, the protrusions and burrs on the medium surface that inevitably occur will be reduced, so the frequency of contact between the magnetic head and the medium will be reduced when the spacing is lowered, and recording and playback will be performed with a narrower spacing than before. It becomes possible to do. Therefore, it is possible to improve the recording / reproducing characteristics while ensuring the reliability.

Further, since a texture having small irregularities is formed, it becomes possible to use abrasive grains having a smaller grain size than in the past, and it is possible to control even a microscopic surface shape extremely uniformly. Therefore, the problem that the recording / reproducing characteristics fluctuate within the disc surface or between lots is solved.

If the polishing conditions of the disk surface are set so that the Ra value is 0.5 nm or more and less than 10 nm and the Rmax value is 5 nm or more and less than 100 nm, the magnetic head and the medium come into contact with each other when the spacing is lowered. It is possible to perform recording and reproduction with a low spacing, since the frequency of use is reduced.
Further, the narrow spacing operation for obtaining a high recording density can be dealt with by setting the Ra value in the range of 0.5 nm or more and less than 5 nm and the Rmax value in the range of 5 nm or more and less than 50 nm.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to examples. FIG. 1 schematically shows a vertical cross-sectional structure of a thin film magnetic recording medium according to the present invention. In the figure,
Reference numeral 11 is a magnetic disk substrate made of Al-Mg alloy, chemically strengthened glass, organic resin, ceramics or the like, and 12 and 12 'are NiP and NiW formed on both surfaces of the substrate 11.
It is a non-magnetic plating layer made of P or the like. When an Al-Mg alloy is used as the substrate, one having such a plating layer is used as the substrate of the magnetic disk. 13 and 1
3'is a metal underlayer formed of chromium, molybdenum, tungsten or an alloy containing any of chromium, molybdenum, and tungsten as a main component formed on the plated layers 12, 12 ', and 14 and 14' are CoNi, CoCr, CoRe, CoPt, CoP formed on the
CoFe, CoNiZr, CoCrAl, CoCrT
a, CoCrPt, CoNiCr, CoCrNb, Co
NiP, CoNiPt, metallic magnetic layer made of CoCrSi like, carbon 15 and 15 'are formed on the said magnetic film, _{boron, B 4 C, SiC, SiO} 2, Si 3 N 4,
Non-magnetic protective films made of WC, WMoC, WZrC, etc. are shown respectively.

FIG. 2 schematically shows a texture forming process and a texture structure of the thin film magnetic recording medium according to this embodiment. In the figure, reference numeral 21 is a disk substrate, 22 is a polishing tape in a tape polishing machine, 23 is a contact roll in the machine, 24 is an abrasive, 25 is a texture formed in the radial direction of the disk substrate surface, and 26 is a disk substrate surface. Is a texture formed in the circumferential direction.

Example 1 Outer diameter 130 mm, inner diameter 40 m
Ni-12P (wt%) on both sides of a disk substrate made of Al-4Mg (the number preceding the atomic symbol indicates the content of the material. In this case, wt%), and the thickness is 1.9 mm. And a plating layer having a film thickness of 13 μm was formed. The surface of this non-magnetic substrate was smooth-polished using a lapping machine until the center line average roughness Ra was 5 nm or less, washed, and dried.

Then, using a tape polishing machine as shown in FIG. 2, while rotating the substrate 21, the polishing tape 22 is pressed against both sides of the disk surface through the contact rolls 23, and the polishing tape is transferred to the disk in the presence of the polishing agent 24. Was vibrated in the radial direction to form a radial texture 25 on the substrate surface. Next, while rotating the disk substrate, the polishing tape was pressed against both sides of the disk surface through the contact rolls in the presence of an abrasive to form a texture 26 in the circumferential direction on the disk substrate. At that time, the texture in the radial direction was prevented from disappearing. Finally,
Dirt such as abrasives adhered to the substrate was washed off and dried.
The surface roughness of the substrate thus obtained was determined by a stylus type surface roughness meter, a scanning tunneling microscope, an electron beam three-dimensional roughness measuring device, or the like. Furthermore, as a result of observing the fine texture structure of the substrate surface with a scanning electron microscope, a scanning tunnel microscope, an electron beam three-dimensional roughness measuring device, etc., it was confirmed that textures in both the circumferential direction and the radial direction were mixed. It was

As a comparative example, a disk substrate having a texture only in the substantially circumferential direction was manufactured. The surface roughness at this time was made equal to that of this example. After loading such a disk substrate into a magnetron sputtering device,
The temperature was maintained at a temperature of ° C, and a chromium underlayer film having a film thickness of 50 nm was formed under the condition of an argon pressure of 5 mTorr. A 40 nm-thickness metal magnetic film made of Co-12Cr-4Ta (atomic%) was laminated on the base film. After that, a carbon protective film having a film thickness of 20 nm was formed on the magnetic film, and finally, a lubricating layer of adsorbable perfluoroalkyl polyether or the like was formed on the protective film.

The recording / reproducing characteristics of the media of the present example and the comparative example formed in this way were measured at a relative velocity of 12 m / s, a flying spacing of 0.1 μm, and an effective gap length of 0.4 μm.
Measured using a thin film magnetic head with a track width of 10 μm,
The values of modulation (Md), output half recording density (D ₅₀ ) and medium S / N were determined. Here, the modulation Md is defined by the formula Md = (HL) / (H + L) by the maximum output H and the minimum output L in the disk plane. Also, the maximum value of the dynamic friction coefficient (μ
f) is magnetic head material Al ₂ O ₃ .TiC, weighted 10 g
f, measured at a relative speed of 0.5 m / sec. further,
Immediately after the production and after 50,000 contact start-and-stop (hereinafter abbreviated as CSS) times, the number of recording / reproducing error bits per disk recording surface was measured to measure the increase in the number of errors before and after CSS.

Table 1 shows the maximum values of the dynamic friction coefficient (μf) and CSS when Ra and Rmax are changed equally to form a texture for each of the media of this example and the comparative example.
The increase in the number of errors before and after and the measured value of modulation (Md) are shown.

[0027]

[Table 1]

It can be seen from Table 1 that the medium of this example has a smaller dynamic friction coefficient, an increase in the number of errors before and after CSS, and a smaller modulation at the time of recording / reproducing even with the same surface roughness, as compared with the comparative example. In particular, it can be seen that under the forming conditions where the surface roughness value is extremely small, the medium of this example has a significantly smaller dynamic friction coefficient (μf), an increase in the number of errors before and after CSS, and a smaller modulation than the comparative example. In addition, the medium of the present example has an output half recording density (D
₅₀ ), and it was confirmed that the medium S / N value was high.

From the above results, it is understood that the surface roughness of the highly reliable medium is preferably 0.5 nm or more and 9.8 nm or less as the Ra value range and 5 nm or more and 93 nm or less as the Rmax value range. Further, when particularly high reliability is required, the Ra value is 0.5 nm or more and 4.9 nm or more.
Hereafter, it is understood that the Rmax value is preferably in the range of 5 nm or more and 49 nm or less.

<Embodiment 2> In the texture forming step of Embodiment 1, the frequency of the polishing tape and the rotational speed of the disk substrate are set to various values, and the direction angle (A) of the circumferential texture shown in FIG. And disk substrates with different direction angles (B) in the radial texture direction were formed. At this time, the surface roughness was controlled so that Ra = 1 nm and Rmax = 9 nm. The values of the directional angles A and B of each texture were observed by a scanning electron microscope, a scanning tunneling microscope, an electron beam three-dimensional roughness measuring device, etc., and the average value was obtained.

As a comparative example, a disk substrate having a texture only in the substantially circumferential direction was manufactured. The surface roughness at this time was controlled to be equal to that of this example. Next, the disk substrates of the present example and the comparative example were loaded into a magnetron sputtering apparatus by the same method as in Example 1, and C
r-10Ti (atomic%) base film, Co-13Cr-4P
A metal magnetic film of t (atomic%) and a carbon protective film were sequentially laminated, and finally a lubricating layer of perfluoroalkyl polyether or the like was formed.

The recording / reproducing characteristics of the media of the present example and the comparative example thus formed were measured by the same method as in Example 1, and the modulation (Md), medium S / N, and output half recording density (D ₅₀ ) The value was measured. The dynamic friction coefficient (μf) and the increase in the number of errors before and after CSS were measured by the same method as in Example 1.

In Table 2, when the direction angles A and B are changed,
Dynamic friction coefficient (μf), modulation (Md), medium S
The value of / N is shown.

[0034]

[Table 2]

It can be seen from Table 2 that the medium of this example has a smaller dynamic friction coefficient and smaller modulation and a larger medium S / N than those of the comparative example when the value of the direction angle A is changed within a range of 19 degrees or less. Recognize. Further, it can be seen that when the value of the direction angle B is changed within the range of 44 degrees or less, the dynamic friction coefficient and the modulation are small and the medium S / N is large as compared with the comparative example. It was also confirmed that the increase in the number of errors before and after CSS was smaller than that in the comparative example, and that the output half recording density (D ₅₀ ) during recording and reproduction was high. The above results show that the Ra value is 0.
5 nm or more and less than 10 nm, Rmax value is 5 nm or more and 100
It was similarly recognized in the range of less than nm. Further, in order to particularly improve reliability, Ra value is 0.5 nm or more and less than 5 nm,
It was confirmed that the Rmax value is preferably in the range of 5 nm to 50 nm.

Example 3 A composite thin film magnetic head having four magnetic disks of Example 1 or 2 as a recording medium, CoTaZr alloy as a recording magnetic pole material, and a magnetoresistive system in the reproducing portion was used. A magnetic recording device was produced by combining seven magnetic recording devices. As shown in FIG.
1, a magnetic recording medium driving unit 32, a magnetic head 33, a magnetic head driving unit 34, a recording / reproducing signal processing system 35, and the like. Using this magnetic recording device, when the average time until an error occurred at a spacing of 0.08 μm was obtained, it was found that it has a life of 5 times or more as compared with the magnetic recording device using the recording medium of the comparative example. We were able to demonstrate that the reliability was extremely high. Further, since the magnetic recording device prototyped in this embodiment has a small spacing, the phase margin in recording / reproducing a signal becomes wide, and the areal recording density can be doubled as compared with the comparative example. Could be provided.

In this embodiment, the case of using the thin film magnetic head using the CoTaZr alloy as the magnetic pole material has been described.
Metal-in-gap type with alloy etc. provided in the gap
It has been confirmed that the same effect can be obtained when a (MIG) recording / reproducing composite magnetic head, an inductive thin film head or a MIG head is used.

[0038]

According to the present invention, it is possible to provide a magnetic recording medium capable of high density recording and a small-sized and large-capacity magnetic recording apparatus using the same.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural diagram of a thin film magnetic recording medium of one embodiment of the present invention.

FIG. 2 is a schematic diagram of a texture forming process and a texture structure of a thin film magnetic recording medium according to the present invention.

FIG. 3 is a vertical cross-sectional structural diagram of a magnetic recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

11 ... Magnetic disk substrate, 12, 12 '... Non-magnetic plating layer, 13, 13' ... Metal base film, 14, 14 '... Metal magnetic film, 15, 15' ... Non-magnetic protective film, 21 ... Disk substrate, 22 … Contact rolls, 23… Abrasive tapes, 24
... polishing agent, 25 ... radial texture, 26 ... circumferential texture, 31 ... magnetic recording medium, 32 ... magnetic recording medium drive section, 33 ... magnetic head, 34 ... magnetic head drive section,
23 ... Recording / reproducing signal processing system.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Ohno 1-280 Higashi Koikeku, Kokubunji City, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Inventor Yasuo Yaku 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Central Research Laboratory (72) Inventor Yukio Kato 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory Hitachi, Ltd. (72) Inventor Tomoh Yamamoto 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Research Center Co., Ltd. In-house

Claims (7)

[Claims] 1. A magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed on the surface of the non-magnetic disk substrate, wherein each of the circumferential texture and the radial texture is at least 1 on the non-magnetic disk substrate surface. A magnetic recording medium characterized by being formed in a direction. 2. The non-magnetic disk substrate is a substrate made of Al--Mg alloy, chemically strengthened glass, organic resin, ceramics, etc., on which a non-magnetic plating layer made of NiP, NiWP, etc. is formed. The magnetic recording medium described. 3. The Ra value range of the non-magnetic disk substrate surface is 0.5 nm or more and less than 10 nm, and the Rmax value range is 5.
The magnetic recording medium according to claim 1 or 2, which has a thickness of not less than 100 nm and less than 100 nm. 4. The Ra value range of the non-magnetic disk substrate surface is 0.5 nm or more and less than 5 nm, and the Rmax value range is 5 n.
The magnetic recording medium according to claim 3, wherein the magnetic recording medium has a length of m or more and less than 50 nm. 5. The magnetic recording medium according to claim 1, further comprising a base film formed between the non-magnetic disk substrate and the magnetic film. 6. The magnetic recording medium according to claim 5, wherein a protective film is formed on the magnetic film. 7. A magnetic recording device comprising a magnetic recording medium, a magnetic recording medium rotation drive unit, a magnetic head, a magnetic head drive unit, and a recording / reproducing signal processing system. Is a magnetic recording medium according to any one of claims 1 to 6.