JPH06187637A - Magnetic recording medium, its production and magnetic recording device - Google Patents

Abstract

PURPOSE:To obtain a recording medium having high reliability suitable for high-density recording by forming a magnetic recording medium in such a manner that the wavelength spectrum of surface roughness shows the max. in each of several wavelength regions. CONSTITUTION:Both surfaces of a 130mmphi NiP-plated Al-Mg alloy substrate 11 rotating at 500rpm in the direction of arrow A in the figure are in contact with polishing cloths 12, 12' pressed with polyurethane press rollers 13, 13'. A slurry-state complex abrasive powder 14, 14' consisting of 10wt.% diamond powder having 1mum average particle size and CeO2 having 0.1mum average particle size dispersed in a hydrophilic solvent is supplied through nozzles 15, 15' to between the substrate and the polishing cloth. The polishing cloth 12, 12' is traveled in the direction of arrow B at 1cm/sec speed and moved back and forth by three times in the direction of arrow C to polish the whole surface of the substrate 11. Thus, a substrate for a magnetic disk is obtd. The obtd. magnetic recording medium has such a surface state that wavelength spectrum of surface roughness shows the max. in each of several regions of wavelength between 1nm and 200mum.

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 used in a rigid type magnetic disk device and the like, a method of manufacturing the same, and a magnetic storage device.

[0002]

2. Description of the Related Art In order to cope with high density of magnetic recording, research and development of a magnetic recording medium using a thin film magnetic layer such as an iron oxide thin film, an iron nitride thin film and a magnetic alloy thin film as a recording layer is under way. These thin film media are often formed on a non-magnetic substrate by a method such as a sputtering method, a vacuum deposition method, a plating method or an ion plating method. It can be said that these are suitable for increasing the recording density because of their small film thickness and large coercive force and magnetization. With the increase in the amount of information in recent years, magnetic storage devices are required to have larger capacities and smaller sizes. In order to deal with this, high recording density and high reliability of the magnetic recording medium are indispensable. However, a magnetic recording medium having a thin-film magnetic layer as a recording layer has a smooth surface, so that the magnetic layer is less likely to have anisotropy, the magnetic characteristics are less likely to be uniform, and the magnetic head and the magnetic recording medium are easily attracted to each other. Point, and CSS (contact / start /
The problem was that the (stop) characteristics were inferior. Overcoming the above-mentioned problems is extremely important for a magnetic recording medium in order to realize high recording density and high reliability.

In the conventional magnetic recording medium, in order to solve the above-mentioned problems, a method of polishing a non-magnetic substrate surface to form a large number of polishing marks (Japanese Patent Laid-Open Nos. 63-42027 and 63-42027).
63-121123, JP-A-2-31326), or a method of performing two-step polishing on the surface of a non-magnetic substrate using a plurality of types of abrasive grains having different grain sizes (JP-A-1-162229). Etc. have been proposed.

[0004]

However, according to the study by the present inventors, in the case of the conventional magnetic recording medium in which a large number of polishing marks are formed by polishing the surface of the non-magnetic substrate, It was revealed that the wavelength spectrum of the surface roughness of the magnetic recording medium has only one maximum value in the region of wavelength 1 nm or more and 200 μm or less. This is because only one type of abrasive is used as the abrasive grains, so in some cases the abrasion marks are too large and the sliding resistance is excellent, but the effect of improving the magnetic characteristics is small, and in some cases vice versa,
Although it has a small polishing mark and is excellent in improving the magnetic properties,
In many cases, the sliding resistance is inferior, and there is a problem that it is difficult to satisfy both the magnetic characteristics and the sliding resistance. on the other hand,
In the case of another conventional technique in which the non-magnetic substrate surface is subjected to two-step polishing using abrasive grains having different grain sizes, there is a problem that the number of processes is increased and the productivity is deteriorated.

An object of the present invention is to polish the surface of a non-magnetic substrate with a composite abrasive grain composed of plural kinds of abrasives, or to etch the surface of a magnetic recording medium to obtain a wavelength of surface roughness of the magnetic recording medium. The spectrum has a wavelength of 1 nm or more 200
A magnetic recording medium having a high reliability suitable for high-density recording having both magnetic characteristics and anti-sliding characteristics and a method of manufacturing the same, and a large high reliability It is to provide a capacitive magnetic storage device.

[0006]

In order to achieve the above-mentioned object, the present invention is one in which the wavelength spectrum of the surface roughness of a magnetic recording medium has a maximum value in each of a plurality of regions having a wavelength of 1 nm or more and 200 μm or less. Is.

At least one region where the maximum value of the wavelength spectrum of the above surface roughness exists has a wavelength of 1 nm or more.
It is desirable to include at least a range of 0 nm or less, a wavelength of 50 nm or more and 5 μm or less, or a wavelength of 5 μm or more and 200 μm or less. This is accomplished in one step at the same time by including polishing the non-magnetic substrate surface with a composite abrasive consisting of multiple abrasives, or after polishing with at least one abrasive, the magnetic layer is This is achieved by forming projections on the surface of the magnetic recording medium after the formation, or after forming the magnetic layer and the protective coating layer, by a treatment such as etching.

The scratches formed on the surface of the magnetic recording medium are substantially parallel to the circumferential direction of the magnetic recording medium, oblique to the circumferential direction of 2 degrees to 45 degrees, and isolated protrusions. Any of these may be used, and further, two or more of these may coexist.

The composite abrasive grain preferably contains a plurality of types of abrasives having different compositions. Further, it is more preferable that the composite abrasive grains simultaneously contain an abrasive having a Mohs hardness of 8 or more and an abrasive having a Mohs hardness of 7 or less. Abrasives with a Mohs hardness of 8 or higher include, for example:
Abrasives having a Mohs hardness of 7 or less, such as diamond, Al ₂ O ₃ and SiC, are, for example, Cr ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ and C.
Examples thereof include eO ₂ and MgO, but abrasives having other compositions may be used. The composite abrasive may contain a plurality of types of abrasives having different average particle diameters, and the average particle diameter is 0.5 μm or more and 5 μm or more.
It is more preferable when the following abrasives and the abrasives having an average particle size of 0.01 μm or more and 0.5 μm or less are contained at the same time. The content of one abrasive contained in the composite abrasive is the total amount of the composite abrasive is 1
It is desirable that the content of 00 wt% be 1 wt% or more and 99 wt% or less.

The method for forming isolated protrusions on the surface of the magnetic recording medium is plasma etching with argon, oxygen, nitrogen or the like using a patterned mask or a particle mask, or the covering layer is partially formed when the protective covering layer is formed. The material and film forming conditions may be selected so that the abnormal growth occurs.

Combining such a magnetic recording medium with a magnetic head containing a magnetic metal alloy or a magnetoresistive effect element in a part of the magnetic core and substantially using zirconia, alumina titanium carbide or ferrite as a main component of the magnetic core. As a result, it is possible to manufacture a highly reliable magnetic storage device having a storage capacity larger than that of the conventional one by 1.5 times or more. In particular, by combining a magnetic recording medium having a plurality of magnetic layers with a magnetic head including a magnetoresistive effect element in a part of a magnetic core, the storage capacity is more than twice as large as the conventional one, and the magnetic storage is highly reliable. A device can be made.

[0012]

The effect of a large number of polishing marks formed on the surface of the non-magnetic substrate on improving the magnetic properties is that the magnetic anisotropy is imparted by aligning the crystal orientation of the magnetic layer to make the magnetic properties uniform over the entire recording surface. That is the point. Therefore, for this purpose, it is as large as the crystal grains of the magnetic layer, that is, a few n
A relatively small polishing mark having a wavelength of m to several tens of nm is effective. If the polishing marks are too large, there is little effect on improving the magnetic properties.

On the other hand, the large number of polishing marks formed on the surface of the non-magnetic substrate have the effect of improving the anti-sliding property by reducing the true contact area when the magnetic head and the magnetic recording medium come into contact with each other.
It is to prevent both from sticking together, and to keep the friction coefficient at CSS low. Therefore, for this purpose, the shape of the surface of the magnetic recording medium should be as rough as possible, that is, a relatively large polishing mark or protrusion having a wavelength of several tens nm or more is effective. If the polishing marks are too small, there is little effect on improving the sliding resistance.

However, when the surface of a non-magnetic substrate is polished by using only one type of abrasive as abrasive grains, the magnetic characteristics are excellent but the sliding resistance is inferior. It was revealed that it is difficult to achieve both magnetic properties and anti-sliding properties, such as excellent sliding properties but poor magnetic properties. This is because, in some cases, the polishing mark is too small, and in some cases, the polishing mark is too large, because only one size of the polishing mark can be formed. Fourier analysis of the wavelength component of the surface roughness of this magnetic recording medium revealed that it had only one maximum value in the region of wavelength of 1 nm or more and 200 μm or less. On the other hand,
It is possible to achieve both magnetic properties and anti-sliding properties even when two-step polishing is performed on the surface of a non-magnetic substrate using abrasive grains with different grain sizes, but the number of processes increases and productivity is poor. There was a problem of becoming.

On the other hand, according to the studies made by the present inventors, the wavelength characteristics of the surface roughness of the magnetic recording medium are maximized in a plurality of wavelength regions to achieve both magnetic characteristics and anti-sliding characteristics. Is possible. That is, as a comparatively small polishing mark suitable for improving magnetic characteristics, 1 nm or more and 50 n
It is important to have a wavelength of m or less. Wavelength 1 nm
This is because below is not preferable because it is excessively smaller than the crystal grains of the magnetic layer, and above 50 nm it is not preferable because it is excessively larger than the crystal grains of the magnetic layer.

On the other hand, it is important to have a wavelength of 50 nm or more and 5 μm or less as a relatively large polishing mark suitable for improving the sliding resistance. When the wavelength is 50 nm or less, it is not preferable because the abrasion mark is too small and the area of contact between the magnetic head and the magnetic recording medium is large and the friction coefficient is large, and when the wavelength is 5 μm or more, the abrasion mark is too large and the floating characteristics of the magnetic head are deteriorated. Because there is no. Further, in the case of providing relatively large isolated protrusions suitable for improving the sliding resistance, it is important to have a wavelength of 5 μm or more and 200 μm or less. This is because when the wavelength is 5 μm or less, the protrusion itself is too fine to form, and when the wavelength is 200 μm or more, the protrusion is too large to be ignored compared with the size of the magnetic head, which deteriorates the flying characteristics of the magnetic head, which is not preferable.

These can be achieved at the same time in one step by polishing the surface of the non-magnetic substrate with a composite abrasive grain composed of plural kinds of abrasives, or by forming a projection on the surface of the magnetic recording medium by a treatment such as etching. Can be achieved. The scratches formed on the surface of the magnetic recording medium may be substantially parallel to the circumferential direction of the magnetic recording medium, oblique to the circumferential direction of 2 degrees or more and 45 degrees or less, or isolated protrusions. It is good because both magnetic properties and sliding resistance properties can be achieved at the same time. Furthermore, when these two or more coexist, it is easy to control the magnetic characteristics and the sliding resistance, which is preferable. In the case of scratches skewed in the circumferential direction, the effect of skewing cannot be obtained if the angle is 2 degrees or less, and if the angle is 45 degrees or more, the effect of aligning the crystal orientation of the magnetic layer in the circumferential direction decreases. Therefore, it is not preferable.

It is preferable to use a plurality of types of abrasives having different compositions because the polishing characteristics of each abrasive can be utilized individually. That is, since abrasives having a Mohs hardness of 8 or more, such as diamond, Al ₂ O ₃ , and SiC, have a high hardness, large scratches can be formed, and abrasives having a Mohs hardness of 7 or less, such as Cr ₂ O ₃ , SiO ₂ , and Fe. ₂ O ₃ ,
Since CeO ₂ , MgO and the like have relatively low hardness, small polishing marks can be formed. Therefore, it is more preferable to use both abrasives having different compositions at the same time. In addition, an abrasive having other composition may be used.

The composite abrasive grains may be composed of a plurality of types of abrasives having different average particle sizes, and an abrasive having an average particle size of 0.5 μm or more and 5 μm or less and an abrasive having an average particle size of 0.01 μm or more and 0.5 μm or less. It is preferable to simultaneously include a relatively small polishing mark suitable for improving the magnetic properties and a relatively large polishing mark suitable for improving the sliding resistance property in one step. An abrasive having an average particle size of 0.01 μm or more and 0.5 μm or less is preferable in order to form relatively small polishing marks suitable for improving magnetic properties. The reason is that when the average particle diameter is 0.01 μm or less, the polishing action cannot be effectively obtained, which is not preferable.
This is because if it is 5 μm or more, the polishing mark becomes too large, which is not preferable.

An abrasive having an average particle size of 0.5 μm or more and 5 μm or less is preferable in order to form a relatively large polishing mark suitable for improving the sliding resistance. Because the average particle size is 0.5 μm
The following is not preferable because the polishing marks become too small,
This is because if it is 5 μm or more, the polishing mark becomes too large and the flying characteristics of the magnetic head are deteriorated, which is not preferable. A plurality of types of abrasives having different average particle diameters have the same effect even if they have the same composition or different compositions.

The content of one abrasive contained in the composite abrasive grains is preferably 1 wt% or more and 99 wt% or less, with the total amount of the composite abrasive grains being 100 wt%. Content is 1w
If it is t% or less, the polishing action cannot be effectively obtained, which is not preferable, and if the content exceeds 99 wt%, the content of other contained abrasives becomes 1 wt% or less, so that the effect of combining a plurality of kinds of abrasives is obtained. Is small, which is not preferable. In addition,
When polishing, either with the polishing agent fixed to the polishing cloth or with the polishing cloth and the polishing agent separated,
The same effect can be obtained.

A magnetic recording medium according to the present invention is combined with a magnetic head including a magnetic metal alloy or a magnetoresistive effect element in a part of a magnetic core and substantially containing zirconia, alumina titanium carbide or ferrite as a main component of the magnetic core. This is preferable because a highly reliable large-capacity magnetic storage device can be manufactured. Zirconia,
Alumina titanium carbide and ferrite are 0.0
This is because the anti-sliding property is improved because it has a thermal conductivity of 05 cal / sec / cm / deg or more and less thermal strain and thermal volatilization of the lubricant. In particular, by combining a magnetic recording medium having a plurality of magnetic layers and a magnetic head including a magnetoresistive effect element in a part of a magnetic core, medium noise can be reduced and signal reproduction capability can be increased.
It is possible to manufacture a highly reliable magnetic storage device having a storage capacity that is at least twice as large as the conventional one.

[0023]

【Example】

<Embodiment 1> FIG. 1 is an explanatory view of a polishing apparatus according to Embodiment 1 of the present invention.

A polishing cloth 12 is formed on both the front and back surfaces of the non-magnetic substrate 11 rotating at 100 to 1000 rpm in the direction of arrow A.
12 'is pressed by the pressure rollers 13 and 13' with a force of 0.1 to 10 kgf. The polishing cloths 12 and 12 'run in the direction of arrow B at a speed of 0.01 to 10 cm / sec, and new polishing cloth is supplied to the substrate surface, and the polishing cloths 12 and 12' simultaneously reciprocate in the direction of arrow C. You can move and polish the entire surface of the substrate. The abrasive grains 14 and 14 'are supplied between the substrate surface and the polishing cloth through nozzles 15 and 15'.

Next, this embodiment will be described. Arrow A
The polishing cloths 12 and 12 'made of polyester woven cloth on both sides of the NiP-plated Al-Mg alloy substrate 11 of 130 mmφ rotated at 500 rpm in the direction of the direction of 2.5 kgf with polyurethane pressure rollers 13 and 13'. Pressed with 10 wt% diamond with an average particle size of 1 μm and an average particle size of 0.1.
1 μm CeO ₂ 90 wt% slurry-like composite abrasive particles 14 and 14 ′ dispersed in a hydrophilic solvent are used to form nozzles 15 and 1.
While supplying the polishing cloth 12 and 12 'between the substrate surface and the polishing cloth via 5', the polishing cloth 12 and 12 'are made to run at a speed of 1 cm / sec in the direction of arrow B, and reciprocated three times in the direction of arrow C to make the entire surface of the substrate. Was polished to obtain a magnetic disk substrate. The scratches formed on this substrate were substantially parallel to the circumferential direction of the substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed. That is,
DC magnetron sputtering method on non-magnetic substrate 21, substrate temperature 250 ° C., argon gas pressure 1 mTorr, input power 3
W / cm ² Cr underlayer 22, 22 with a thickness of 50nm in ', Co with a thickness of _{50nm 0. 87 Cr 0. 10} Ta 0. 03 magnetic layer 23,2
After forming 3 ', a C protective coating layer 24, 24' is formed by DC magnetron sputtering at a substrate temperature of 250 ° C., an argon gas pressure of 5 mTorr, and an input power of 10 W / cm ² to 30 nm, and an adsorption containing an OH group at the end. A perfluoroalkylpolyether-based lubricating layer 25, 25 'having a group was provided to a thickness of 5 nm to obtain a magnetic recording medium.

<Embodiment 2> Next, still another embodiment will be described with reference to the drawing of the polishing apparatus shown in FIG.

Abrasive cloths 12, 12 'made of polyamide woven cloth are applied on both sides of a 95 mmφ amorphous carbon substrate 11 rotated at 600 rpm in the direction opposite to arrow A by a polyurethane pressure roller 13, 13' with a force of 2 kgf. Slurry composite abrasive grains 14, 14 'in which 15 wt% diamond having an average grain size of 0.75 μm and 85 wt% Cr ₂ O ₃ having an average grain size of 0.25 μm are dispersed in a nozzle 15, 15 While feeding between the substrate surface and the polishing cloth through the ‘′, the polishing cloth 12, 12 ′ is 0.5 cm / sec in the direction of arrow B.
Was run at a speed of 3, and was reciprocated three times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate. The scratches formed on this substrate were substantially parallel to the circumferential direction of the substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed under the same conditions as in Example 1.

<Embodiment 3> Next, still another embodiment will be described with reference to the drawing of the polishing apparatus shown in FIG.

6 rotated in the direction of arrow A at 600 rpm
Abrasive cloths 12 and 12 'made of cellulose woven cloth were pressed on both surfaces of a 5 mmφ titanium alloy substrate 11 with a polyurethane pressure roller 13 and 13' with a force of 2 kgf, and 10 wt% of diamond having an average particle diameter of 0.75 μm, Average particle size of 0.
7 μm Al ₂ O ₃ 5 wt%, C with an average particle size of 0.25 μm
eO ₂ 45 wt% and SiO _{2 having an} average particle size of 0.1 μm
While supplying slurry-like composite abrasive grains 14 and 14 'in which 40 wt% is dispersed in a lipophilic solvent through the nozzles 15 and 15' between the substrate surface and the polishing cloth, the polishing cloths 12 and 12 'are indicated by arrow B.
In the direction of 0.5 cm / sec and reciprocated four times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate. The scratches formed on this substrate were substantially parallel to the circumferential direction of the substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed under the same conditions as in Example 1.

<Fourth Embodiment> Next, still another embodiment will be described with reference to FIG.

13 rotated in the direction of arrow A at 50 rpm
Polishing cloths 12 and 12 'made of polyester woven cloth are pressed on both front and back surfaces of a 0 mmφ NiP-plated Al-Mg alloy substrate 11 with polyurethane pressure rollers 13 and 13' with a force of 2.5 kgf to obtain an average particle diameter of 1 μm. Diamond 10wt
%, And 90 wt% CeO ₂ having an average particle size of 0.1 μm dispersed in a hydrophilic solvent while supplying slurry-like composite abrasive grains 14, 14 ′ through nozzles 15, 15 ′ between the substrate surface and the polishing cloth. , Polishing cloth 12, 12 'in the direction of arrow B at 100 cm / se
It was run at a speed of c and reciprocated 50 times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate.
The scratch formed on this substrate had an angle of about 15 degrees with the circumferential direction of the substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed under the same conditions as in Example 1.

<Embodiment 5> Next, still another embodiment will be described with reference to the drawing of the polishing apparatus shown in FIG.

4 rotated in the direction of arrow A at 500 rpm
Polishing cloths 12 and 12 'made of polyester woven cloth are pressed against the front and back surfaces of an NiP plated Al-Mg alloy substrate 11 of 8 mm in diameter with a pressure roller of polyurethane type 13 and 13' with a force of 2.5 kgf to obtain an average particle diameter of 1 μm. Diamond 10wt
%, And 90 wt% CeO ₂ having an average particle size of 0.1 μm dispersed in a hydrophilic solvent while supplying slurry-like composite abrasive grains 14, 14 ′ through nozzles 15, 15 ′ between the substrate surface and the polishing cloth. The polishing cloths 12 and 12 'were run in the direction of arrow B at a speed of 1 cm / sec, and reciprocated three times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate. The scratches formed on this substrate were substantially parallel to the circumferential direction of the substrate.

Next, a magnetic recording medium having the structure shown in FIG. 2 was formed using the obtained magnetic disk substrate. That is,
DC magnetron sputtering method on non-magnetic substrate 21, substrate temperature 250 ° C., argon gas pressure 1 mTorr, input power 3
W / cm ² Cr underlayer 22, 22 with a thickness of 50nm in ', Co with a thickness of _{50nm 0. 87 Cr 0. 10} Ta 0. 03 magnetic layer 23,2
After forming 3 ', the C protective coating layers 24, 24' were formed by DC magnetron sputtering at a substrate temperature of 250 ° C., an argon gas pressure of 5 mTorr and an input power of 10 W / cm ² to a thickness of 30 nm. Next, using Teflon particles having an average particle diameter of 3 μm as a mask, the C protective coating layers 24 and 24 ′ were etched by oxygen plasma for 10 nm to form isolated protrusions. Finally, a perfluoroalkylpolyether-based lubricating layer 25, 25 'having an adsorption group containing an OH group at the end was provided to a thickness of 5 nm to obtain a magnetic recording medium.

<Embodiment 6> Next, still another embodiment will be described with reference to the drawing of the polishing apparatus shown in FIG.

Polishing cloths 12, 12 'made of cellulose woven cloth are attached on both front and back sides of a 34 mmφ NiP-plated Al-Mg alloy substrate 11 rotated at 550 rpm in the direction opposite to the arrow A, and polyurethane pressure rollers 13, 13' are used. With a force of 1.8 kgf, 20 wt% diamond with an average grain size of 0.75 μm, 50 wt% CeO _{2 with} an average grain size of 0.25 μm
%, And 30 wt% SiO _{2 having an} average particle size of 0.1 μm dispersed in a lipophilic solvent, slurry-like composite abrasive grains 14, 14 ′
Is supplied between the substrate surface and the polishing cloth through the nozzles 15 and 15 ', while the polishing cloth 12, 12' is moved in the direction of arrow B by 0.5c.
It was run at a speed of m / sec, reciprocated four times in the direction of arrow C, and the entire surface of the substrate was polished to obtain a magnetic disk substrate. The scratches formed on this substrate were substantially parallel to the circumferential direction of the substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 3 was formed. That is, by using a DC magnetron sputtering method on a non-magnetic substrate 31, a substrate temperature of 250 ° C., an argon gas pressure of 1 mTorr, an applied power of 3 W / cm ² , and a thickness of 50 nm of Cr underlayers 32, 3.
2 ', Co having a thickness of _{15nm 0. 87 Cr 0. 10} Ta 0. 03 first magnetic layer 33, 33', having a thickness of 5 nm Cr intermediate layer 34,3
4 ', Co having a thickness of _{15nm 0. 87 Cr 0. 10} Ta 0. 03 second magnetic layer 35, 35' after forming a, C protective coating layer 36,
36 'by DC magnetron sputtering method at substrate temperature 25
0 ℃, Argon gas pressure 5mTorr, Input power 10W / cm ²
With a thickness of 30 nm and having an adsorbing group containing an OH group at the end, a perfluoroalkylpolyether lubricating layer 37, 3
7'of 5 nm was provided to make a magnetic recording medium.

<Comparative Example 1> Next, a comparative example will be described with reference to FIG.

1 rotated in the direction of arrow A at 500 rpm
Polishing cloth 12, 12 'made of polyester woven cloth on both front and back surfaces of a NiP-plated Al-Mg alloy substrate 11 of 30 mmφ, and 2.5 kgf of polyurethane pressure rollers 13, 13'.
The abrasive grains 14 and 14 'in which diamond having an average grain size of 0.2 μm is dispersed in a hydrophilic solvent are pressed between the substrate surface and the polishing cloth through nozzles 15 and 15', and polishing is performed. The cloths 12 and 12 'were run in the direction of arrow B at a speed of 1 cm / sec, and reciprocated three times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed under the same conditions as in Example 1.

<Comparative Example 2> Next, a comparative example will be described with reference to FIG.

1 rotated in the direction of arrow A at 500 rpm
Polishing cloth 12, 12 'made of polyester woven cloth on both front and back surfaces of a NiP-plated Al-Mg alloy substrate 11 of 30 mmφ, and 2.5 kgf of polyurethane pressure rollers 13, 13'.
The abrasive cloth is pressed against the abrasive cloth with an average particle diameter of 3 μm in a hydrophilic solvent and slurry-like abrasive particles 14 and 14 ′ are supplied between the substrate surface and the abrasive cloth through nozzles 15 and 15 ′. 12, 12 'were run in the direction of arrow B at a speed of 1 cm / sec, and reciprocated three times in the direction of arrow C to polish the entire surface of the substrate to obtain a magnetic disk substrate.

Next, using the obtained magnetic disk substrate, a magnetic recording medium having the structure shown in FIG. 2 was formed under the same conditions as in Example 1.

Example 7 Next, the surface roughness of the magnetic recording media of Examples 1 to 6 and Comparative Examples 1 and 2 was measured with an STM (scanning tunneling microscope) and a stylus type surface roughness meter. Then
The waveform was Fourier analyzed. Wavelength of each magnetic recording medium is 1 nm
Table 1 shows the median values of the maximum wavelengths existing in the region of 200 μm or less.

[0049]

[Table 1]

As shown in Table 1, the magnetic recording media of Examples 1 to 6 have a plurality of maximum values in the wavelength range of 1 nm to 200 μm, while the magnetic recording media of Comparative Examples 1 and 2 are:
There was only one maximum in the wavelength range of 1 nm to 200 μm.

Further, the magnetic recording media of Examples 1 to 6 and Comparative Examples 1 and 2 were combined with a thin film magnetic head in which a NiFe alloy was used as a magnetic pole material and a core portion was made of a non-magnetic material containing zirconia as a main component. The magnetic storage device shown in 1 was manufactured, and the recording / reproducing characteristics and the CSS characteristics were evaluated. Figure 4
, 401, 402, 403, 404 are magnetic recording media according to the present invention, and 405, 406, 407, 40.
8, 409, 410, 411 are magnetic heads, 412 is a movable head arm, 413 is a voice coil motor, 41
Reference numeral 4 is a control circuit, 415 is a positioning detection circuit, 416 is a head selection switch, 417 is a recording / reproducing circuit, and 418 is a controller. 65kFCI as recording / reproducing characteristics
S / N and S / N when recording and reproducing the signal
The maximum areal recording density capable of 25 dB or more was adopted as the CSS characteristics, and the coefficient of friction between the magnetic head and the magnetic recording medium at CSS 10,000 times and the number of CSS times until failure occurred.
The results are shown in Table 2.

[0052]

[Table 2]

As shown in Table 2, the magnetic recording media of Examples 1 to 6 have high recording / reproducing characteristics and CSS characteristics.
It became clear that it was significantly superior to 2.

<Example 8> Next, regarding the magnetic recording media of Examples 1 to 6 and Comparative Examples 1 and 2, the magnetoresistive effect element was included in the reproducing portion, and the core portion was made of alumina titanium carbide as a main component. By combining the recording / reproducing separated type magnetic head made of a magnetic material, the magnetic storage device shown in FIG.
Recording / reproducing characteristics and CSS characteristics were evaluated by the same method as in Example 7. The results are shown in Table 3.

[0055]

[Table 3]

As shown in Table 3, it was revealed that the magnetic recording media of Examples 1 to 6 had excellent recording and reproducing characteristics and CSS characteristics, and were significantly superior to Comparative Examples 1 and 2. In the combination of the magnetic recording media of Examples 1 to 6 and the recording / reproducing separated type magnetic head including the magnetoresistive effect element in the reproducing portion, since the flying of the magnetic head is stable, the abnormal discharge when the magnetic head is energized is remarkable. A magnetic storage device with high reliability can be provided by being suppressed. When a layer of C, ZrO ₂ , Al ₂ O ₃ or the like is provided on the surface of the magnetoresistive element,
It is preferable because the reliability of the device can be further improved. In particular,
The combination with a magnetic recording medium including a plurality of magnetic layers is most preferable because a high device S / N can be obtained.

The non-magnetic substrates 11, 21 and 31 are NiP-plated Al alloy, titanium alloy, tempered glass, crystallized glass, plastic, amorphous carbon, ceramics, surface glass coat ceramics, silicon, etc. Any of those known as can be used. Further, either or both of the rotation direction A of the non-magnetic substrate 11 and the polishing cloth feed direction B may be opposite. The width of the polishing cloths 12 and 12 ′ may be smaller than the radius of the non-magnetic substrate 11, the same width, or a large width. The width of the pressure rollers 13, 13 'should be the same as or smaller than the width of the polishing cloth 12, 12'. The abrasive grains 14 and 14 ′ may be only an abrasive, but may be a slurry prepared by dispersing them in a hydrophilic or lipophilic solvent. Underlying layers 22, 22 ',
32, 32 'and intermediate layers 34, 34' include Cr, M
o, W, Cr-Ti, Cr-Si, Cr-W, C, etc., in the magnetic layers 23, 23 ', 33, 33', 35, 35 '.
o-Ni, Co-Ni-Cr, Co-Ni-Zr, Co
-Ni-Pt, Co-Cr, Co-Cr-Ta, Co-
Cr-Pt, Co-Cr-Pt-Si, etc., and C, carbides, nitrides, oxides, borides, etc. can be used for the protective coating layers 24, 24 ', 36, 36', and any combination thereof can be used. However, the same effect can be obtained. Further, the underlayer, the magnetic layer, and the protective coating layer may be composed of an infinite number of layers.

[0058]

According to the present invention, since both magnetic characteristics and anti-sliding characteristics can be achieved at the same time, a highly reliable magnetic recording medium suitable for high density recording, a manufacturing method thereof and a magnetic storage device can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a polishing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the magnetic recording medium according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a magnetic recording medium in Example 6 of the present invention.

FIG. 4 is a block diagram of a magnetic storage device according to a seventh embodiment of the present invention.

[Explanation of symbols]

21 ... Non-magnetic substrate, 22, 22 '... Underlayer, 23, 2
3 '... magnetic layer, 24, 24' ... protective coating layer, 25, 2
5 '... lubrication layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masatoshi Takeshita Masatoshi Takeshita 1-280, Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Akira Ishikawa 1-280, Higashi Koikeku, Kokubunji, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Akira Ozaki 1-280, Higashi Koikekubo, Kokubunji City, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor, Tomoo Yamamoto 1-280, Higashi Koikeku, Kokubunji, Tokyo Hitachi Central Research Center, Ltd. ( 72) Inventor Yukio Kato 1-280, Higashi Koigokubo, Kokubunji City, Tokyo Inside Hitachi Central Research Laboratory

Claims (20)

[Claims] 1. A magnetic recording medium having at least one magnetic layer on a non-magnetic substrate, wherein the wavelength spectrum of the surface roughness of the magnetic recording medium has a maximum value in each of a plurality of regions having a wavelength of 1 nm or more and 200 μm or less. A magnetic recording medium characterized by the above. 2. The magnetic recording medium according to claim 1, wherein at least one region where the maximum value of the wavelength spectrum of the surface roughness of the magnetic recording medium is present is in the range of 1 nm to 50 nm. 3. The magnetic recording medium according to claim 1, wherein at least one region where the maximum value of the wavelength spectrum of the surface roughness of the magnetic recording medium is present is in the range of wavelength 50 nm or more and 5 μm or less. 4. The magnetic recording medium according to claim 1, wherein at least one region where the maximum value of the wavelength spectrum of the surface roughness of the magnetic recording medium is present is in the range of wavelength 5 μm or more and 200 μm or less. 5. The magnetic recording medium according to claim 1, 2, 3 or 4, wherein the surface of the magnetic recording medium has scratches substantially parallel to the circumferential direction of the magnetic recording medium. 6. The method according to claim 1, 2, 3, 4 or 5.
A magnetic recording medium having scratches on the surface of the magnetic recording medium, the scratches being oblique in the circumferential direction of the magnetic recording medium. 7. A magnetic recording medium according to claim 1, 2, 3, 4, 5 or 6, which has isolated protrusions on the surface of the magnetic recording medium. 8. The magnetic recording medium according to claim 7, wherein the protrusions isolated on the surface of the magnetic recording medium are formed by treating the surface of the magnetic recording medium. 9. A method of manufacturing a magnetic recording medium, comprising a step of forming at least one magnetic layer on a non-magnetic substrate, wherein the surface of the non-magnetic substrate comprises a plurality of abrasives as a pre-step of the step. A method for manufacturing a magnetic recording medium, comprising the step of polishing using a magnetic recording medium. 10. The method of manufacturing a magnetic recording medium according to claim 9, wherein the composite abrasive grain contains a plurality of types of abrasives having different compositions. 11. The method for producing a magnetic recording medium according to claim 9, wherein the composite abrasive grains simultaneously contain an abrasive having a Mohs hardness of 8 or more and an abrasive having a Mohs hardness of 7 or less. 12. The Mohs hardness 8 according to claim 11.
The above abrasives are diamond, Al ₂ O ₃ , and SiC in the method of manufacturing a magnetic recording medium. 13. The Mohs hardness according to claim 11,
The following abrasives are Cr ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ , Ce.
A method of manufacturing a magnetic recording medium that is O ₂ or MgO. 14. A method according to claim 9, 10, 11, 12 or 13.
In the method for producing a magnetic recording medium, the composite abrasive grain contains a plurality of types of abrasives having different average grain sizes. 15. The method for producing a magnetic recording medium according to claim 14, wherein the composite abrasive grains include an abrasive having an average particle size of 0.5 μm or more and 5 μm or less and an abrasive having an average particle size of 0.01 μm or more and 0.5 μm or less at the same time. Method. 16. A method according to claim 9, 10, 11, 12, 13, 1.
4 or 15, the content of one abrasive contained in the composite abrasive grains is 1 wt% or more and 99 wt% or less, with the total amount of the composite abrasive grains being 100 wt%. 17. A magnetic memory device according to claim 1, further comprising a magnetic head including the metal magnetic alloy as at least a part of a magnetic core. 18. A magnetic storage device according to claim 1, further comprising a magnetic head including a magnetoresistive effect element as a part of a magnetic core. 19. The magnetic storage device according to claim 18, wherein the magnetic recording medium has a plurality of magnetic layers. 20. The method according to claim 17, 18 or 19,
A magnetic storage device in which the core material of the above magnetic head substantially contains zirconia, alumina titanium carbide, or ferrite as a main component.