JPH04168620A - Magnetic recording medium and magnetic recording/ reproducing method - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high CSS durability and high magnetic properties by providing a special magnetic layer of a continuous thin film type containing gamma-Fe2O3 as a main ingredient on a rigid board. CONSTITUTION:A magnetic layer 3 of a continuous thin film type containing gamma-Fe2O3 as a main ingredient is provided on a rigid board 2, alpha-Fe2O3 exists in a region from the surface of the layer 3 at least to depth of 50Angstrom , and the alpha-Fe2O3 does not exist in a region exceeding the depth of 200Angstrom . When, in an X-ray chart obtained by an X-ray diffraction while polishing or etching the layer 3, the peak area of surface index (104) of the alpha-Fe2O3 is P (104) and the peak area of the surface index (311) of the gamma-Fe2O3 is P (311), it is desirable that the depth in which P(104)/P(311) becomes zero, is 50 - 200Angstrom . Thus, CSS (contact start/stop) durability becomes high, and magnetic properties are improved.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a so-called hard type magnetic recording medium having a magnetic layer on a rigid substrate, particularly a continuous thin film type magnetic recording medium mainly composed of γ-Fe, 03. The present invention relates to a hard type magnetic recording medium having a magnetic layer and a magnetic recording and reproducing method for recording and reproducing information on the magnetic recording medium using a floating magnetic head.

<Conventional technology> Magnetic disk drives used in computers, etc.! A hard type magnetic disk in which a magnetic layer is formed on a rigid substrate and a floating magnetic head are used.

Conventionally, coating-type magnetic disks have been used in such magnetic disk drive devices, but as the capacity of magnetic disks increases, sputtering methods and other methods have been used because they are advantageous in terms of magnetic properties, recording density, etc. Thin-film magnetic disks having a continuous thin-film magnetic layer formed by a vapor phase deposition method or the like have come to be used.

Thin-film magnetic disks are made by plating an N1-P underlayer on an AI2-based disk-shaped metal plate, or by oxidizing the surface of this metal plate to form alumite. It is generally constructed by sequentially depositing a Cr layer, a metal magnetic layer such as Co--Ni, and a protective lubricant film such as C by sputtering.

However, metal magnetic layers such as Co-Ni have low corrosion resistance (and even low hardness), which causes reliability problems.
The magnetic thin film mainly composed of iron oxide as described in Japanese Patent No. 9 is chemically stable, so there is no fear of corrosion, and it also has sufficient hardness.

On the other hand, a flying type magnetic head is a magnetic head having a slider that generates buoyancy, and a composite type in which the core is integrated with the slider, or a monolithic type in which the core also serves as a slider is usually used.

Furthermore, in addition to these, so-called floating thin film magnetic heads are attracting attention because they are capable of high-density recording.
A floating thin film magnetic head has a magnetic pole layer, a gap layer, a coil layer, etc. formed on a substrate by a vapor phase deposition method or the like. In such a floating thin film magnetic head, the base body functions as a slider.

<Problems to be Solved by the Invention> In a magnetic disk drive using a floating magnetic head, the flying surface of the floating magnetic head (surface on the magnetic disk side of the slider) and the magnetic disk come into contact during contact start/stop (CSS). However, the magnetic layer is subjected to impact.

In particular, when using a floating thin-film magnetic head, the distance between the magnetic disk and the magnetic head (flying bite) is set extremely small because high-density recording is possible.
The impact received by the magnetic layer during C8S becomes larger.

Furthermore, if the flying bite is small, an accidental contact between the magnetic disk and the flying magnetic head may occur due to vibration of the magnetic disk or impact from outside the drive device.

JP-A-62-43819, JP-A No. 63-175219
A magnetic disk having a magnetic thin film mainly composed of iron oxide as described in the above publication uses a glass substrate with a mirrored surface, and the surface roughness of the magnetic layer (Rmax
) is very small, less than 100 Å.
In such a magnetic disk, since the flying bite can be set extremely small, the magnetic layer will be seriously damaged in the event of a C8S or head contact accident.

However, Japanese Unexamined Patent Publication No. 62-43819, No. 63-17
Publication No. 5219 does not mention anything about the durability of the magnetic layer, and no other effective proposals have been made to improve the durability of a continuous thin film type magnetic layer containing iron oxide as a main component.

The present invention was made under these circumstances, and aims to realize high durability in a magnetic recording medium having a continuous thin film type magnetic layer mainly composed of γ-Fe2O3 on a rigid substrate. Another object of the present invention is to provide a magnetic recording and reproducing method that can perform highly reliable recording and reproducing on a magnetic recording medium using a floating magnetic head.

Means for Solving the Problems> Such objects are achieved by the present inventions (1) to (4).

(1) A magnetic recording medium having a continuous thin film type magnetic layer containing γ-Fe2eg as a main component on a rigid substrate, wherein α-Fe2O3 is present in a region at least 50 mm deep from the surface of the magnetic layer. , a magnetic recording medium characterized in that α-Fe2rg is substantially absent in a region having a depth exceeding 200 mm.

(2) In the X-ray chart obtained by performing X-ray diffraction while polishing or etching the magnetic layer, α-F
The peak area of the plane index (101,) of eign is defined as P(10
4), and when the peak area of the plane index (311) of 7-Fe, 03 is P(311), P(1,04)/P
(The magnetic recording medium according to (1) above, wherein the depth at which 3111 becomes zero is 50 to 200 people.

(3) In the X-ray diffraction chart of the magnetic layer, a-F
The peak area of the plane index (104) of e2O3 is P(104
), the surface index (311) of γ-Fe*Os, and the surface index (
400) and the surface index (222) as P(311), P(400) and P(222), 0.02≦P(104)/P(311)≦0.200
≦P(400)/P(311)≦1.00≦P(22
2) The magnetic recording medium according to (1) or (2) above, wherein /P(311)≦0.5.

(4) A magnetic recording and reproducing method in which the magnetic recording medium according to any one of (1) to 3) above is rotated and a magnetic head is levitated above the magnetic recording medium to perform recording and reproducing, the magnetic recording and reproducing method comprising: A magnetic recording and reproducing method characterized in that the recording medium is disk-shaped and the flying height of the magnetic head is 0.2- or less.

<Function> The magnetic recording medium of the present invention has high durability because α-Fe2O3 exists in a region at least 50 mm deep near the surface of the magnetic layer containing γ-Fe2es as a main component. Therefore, C8S durability becomes extremely high, and C8S durability at low temperatures also improves. Further, even if an accident such as contact with a magnetic head occurs, the deterioration of the magnetic property 1 is extremely small.

Moreover, α-Fezes can extend up to 200 mm from the surface of the magnetic layer.
Since α-Fe2O3, which is non-magnetic, exists only in the region up to the human body and is substantially absent in deeper regions, the influence of non-magnetic α-Fe2O3 on the magnetic properties of the magnetic layer is extremely small.

<Specific configuration> Hereinafter, a specific configuration of the present invention will be explained in detail.

A magnetic recording medium 1 of the present invention shown in FIG. 1 has a continuous thin film type magnetic layer 3 on a rigid substrate 2. The magnetic recording medium 1 shown in FIG.

The substrate 2 used in the present invention simplifies the manufacturing process since there is no need to provide an underlayer, etc., is easy to polish, and the surface roughness can be easily controlled, and is suitable for heat treatment during the formation of the magnetic layer. It is preferable to use glass because of its durability.

As the glass, it is preferable to use tempered glass, particularly surface-strengthened glass obtained by chemical strengthening. Regarding surface-strengthened glass, see JP-A-62-43819 and JP-A-62-43819.
It is described in Japanese Patent No. 3-175219.

The glass substrate preferably has a contact angle with water of at least the surface on the magnetic layer side of 20° or less, particularly preferably 10° or less.

By setting the contact angle with water within such a range, the adhesion of a continuous thin film type magnetic layer containing iron oxide as a main component as described later is improved. Note that there is no particular restriction on the lower limit of the contact angle, but it is usually about 2° or more.

The contact angle with water may be measured, for example, after dropping pure water on the surface of the glass substrate and 30 seconds later.

The measurement atmosphere is approximately 18 to 23°C and 40 to 60% RH.

In order to obtain such a contact angle, the glass substrate surface is polished, then subjected to the above-mentioned strengthening treatment, the glass substrate surface is polished again, washed with pure water, and then [detergent cleaning] It is preferable to perform the cleaning in the following order: pure water cleaning - organic solvent vapor drying.

The surface roughness (Rmax) of the rigid substrate is preferably 10 to
00 people, more preferably 40 to 80 people, even more preferably 40 to 60 people.

By setting Rmax of the rigid substrate within this range, the durability of the magnetic recording medium is improved, and Rwax of the surface on the magnetic layer side of the medium as described later can be easily obtained.

Note that Rmax may be measured according to JIS B 0601.

Such surface roughness is described, for example, in Japanese Patent Application Laid-Open No. 62-4381.
It can be obtained by mechanochemical polishing as described in Publication No. 9, No. 63-1752].

The material of the glass substrate is not particularly limited and can be appropriately selected from borosilicate glass, aluminosilicate glass, quartz glass, titanium silicate glass, etc. However, aluminosilicate glass is particularly preferred because of its high mechanical strength. It is preferable to use

There are no particular restrictions on the shape and dimensions of the glass substrate, but it is usually disc-shaped and has a thickness of about 0.5 to 5ff1m.
The diameter is about 25-3001II111.

A continuous thin film type magnetic layer containing γ-Fe2O3 as a main component is formed on the rigid substrate.

In the present invention, α-Fe20 is formed only near the surface of this magnetic layer.
Contains a. Specifically, a small amount (
α-Fe20a exists in the region up to 50 people deep,
Substantially no α-Fe2O3 exists in the region where the depth exceeds 200 depths. In other words, α-Fe is present only in a region including the surface of the magnetic layer and a depth of 50 to 200 mm from the surface.
20a does not exist. In addition, in the magnetic layer, α-
Fe20. is in a mixed state with γ-Fezes.

The depth at which α-FezO- exists can be confirmed by performing X-ray diffraction while polishing or etching the magnetic layer.

That is, after removing a certain thickness of the magnetic layer by polishing or etching, an X-ray diffraction chart of the magnetic layer is prepared.

If α-Fe20s is present in the magnetic layer even after polishing or etching, the X-ray diffraction chart shows γ-F.
In addition to the peak of the plane index (311) of e*Os, a-Fe
There is a peak of plane index (104) of xOs. In this case, the magnetic layer is polished or etched again, and X-ray diffraction is performed again. Then, by repeating such polishing or etching and measurement, the area P(104+) of the peak of the plane index (104) of α-Fezes and the
The depth when the ratio P(lcI4)/P(311) of the peak of the JxO surface index (311) to P(3111) becomes zero is the depth of the region where α-Few(ls exists).

Note that the peak area is determined by integrating the portion excluding the background.

In addition, α is applied to the entire region from the surface of the magnetic layer to the above depth.
-The presence of Fe2O3 means that as the polishing or etching depth increases, P(104)/P(313,)
This can be confirmed by the gradual decrease in

Although there are no particular restrictions on the method of polishing the magnetic layer during measurement, it is preferable to use the mechanochemical polishing method using colloidal silica or the like as described above, since a highly smooth polished surface can be obtained. Further, there is no particular restriction on the method of etching the magnetic layer, but it is preferable to use various ion etching methods.

In addition, the X-ray diffraction device used is not particularly limited, but S/
Since N is favorable, it is preferable to use a low incident angle X-ray diffraction apparatus, which will be described later.

The durability of the magnetic layer of the magnetic recording medium of the present invention is determined by α-Fe20. Let P(104) be the peak area of the plane index (104) of 1-Fezox, and the plane index (311), plane index (400) and plane index (222) of 1-Fezox.
The respective peak areas of P(311) and P(400)
and P(222), 0.02≦P(104)/P(311)≦0.200≦
P(400)/P(311)≦1.00≦P(222
)/P(311)≦0. 5, especially 0.05≦P(104)/P(311)≦0.150≦
P(400)/P(311)≦0.60≦P(222
)/P(311)≦0.3, the improvement is further improved.

Note that each peak area in this case is a value when the magnetic layer is not polished or etched.

To explain in more detail, P(104)/P(311)
is less than the above range, the durability improvement effect is relatively low (,
When the above range is exceeded, the recording and reproducing output decreases.

Furthermore, an increase in P(222) indicates that the proportion of (222) planes and (111) planes existing parallel to the magnetic layer plane increases.

γ-Fe2O3 has a spinel structure, and in the spinel structure, the (111) plane is the most slippery plane.

Therefore, if the peak area of the (222) plane parallel to the (,111) plane is large, that is, P(222)/P(311
) is large, it is considered that the γ-Fe2O3 constituting the magnetic layer is likely to slip due to sliding with the magnetic head, resulting in decreased durability.

When P(222)/P(311) exceeds the above range, durability is critically reduced.

The (100) plane that exists parallel to the (400) plane is (11
1) Since it is thought that slippage is likely to occur next to the surface, P(
400)/P(311) exceeds the above range, the durability is critically reduced.

The X-ray diffraction chart for determining the peak area ratio described above is preferably created, for example, as follows.

FIG. 2 shows an example of an X-ray diffraction apparatus.

In FIG. 2, the Xi fountain irradiated from the X-ray source 101 passes through the divergence slit DS to the magnetic recording medium 1.
It enters the magnetic layer 02 and is diffracted, passes through the scatter slit SS and the receiving slit RS, is reflected by the monochromator MM to become monochromatic light, and further passes through the receiving slit RS and enters the counter 10j. A count of the x-ray intensity is taken and typically recorded by a rate meter or the like.

Note that during measurement, the magnetic recording medium 102 has a scanning speed dθ
/dt, the members constituting the optical path below the scatter slit SS are rotated at a scanning speed of 2dθ/dt.

For each peak in the obtained X-ray diffraction chart, a portion excluding the background is integrated to calculate the above-mentioned area ratio.

In addition, in the optical arrangement shown in Fig. 2 using CuKα as the X-ray source, the peak of the plane index (104) of α-Fe, O, is 33
．． Appears around 3°, and the plane index of 7-FeaOx (400
), the peaks of plane index (222) and plane index (311) are 43.5°, 37.3° and 35.6°, respectively.
Appears near °.

FIG. 3 shows an example of a low incident angle X-ray diffraction apparatus suitable for confirming the region where α-Fe20s exists.

In FIG. 3, the X-rays irradiated from the X-ray source 101 are
The light passes through the solar slit S1, enters the magnetic layer of the magnetic recording medium 102 at an angle β with the surface thereof, and is diffracted.

After passing through the solar slit S2, the diffracted X-rays are reflected by a monochromator MM to become monochromatic light,
Furthermore, the X-rays enter the counter tube 103 through the receiving slit RS, and the X-ray intensity is counted.

In this low incidence angle X-ray diffraction apparatus, unlike the apparatus shown in FIG. 2, the magnetic recording medium 102 is incident on Xi! during measurement.
The members constituting the optical path below the solar slit 82 are rotated at a scanning speed of 2dθ/dt.

When confirming the region where α-Fe2e3 exists using this device, it is preferable that the angle β between the incident X-ray and the surface of the magnetic layer is, for example, about 1 to 10°.

The continuous thin film type magnetic layer whose main component is γ-Fe2O3 is
First, Fe5O4 is formed, and this Fe50< is oxidized to form γ
-Fe2es is preferably formed.

The method for forming FexO< may be a direct method or an indirect method, but the direct method is preferred because the above-mentioned peak area ratio can be easily obtained and the process is simple. preferable.

The direct method uses reactive sputtering to deposit Fe3O on the substrate.
This is a method of directly forming 4. The direct method includes an oxidation method using Fe as a target in an oxidizing atmosphere, a reduction method using α-FezO as a target in a reducing atmosphere, and a neutral method using Fe504 as a target. In the present invention, it is preferable to use the oxidation method because sputter control is easy and the film formation rate is high.

In the oxidation method, sputtering is performed by adding 02 gas as a reactive gas to an Ar gas atmosphere.

In order to obtain the above-mentioned peak ratio of γ-Fe2O3 in X-ray diffraction, it is preferable that the partial pressure PO2 of 02 gas and the total pressure P (Ar+(h)) of Ar gas and 02 gas are as follows. , especially preferably.

Further, during sputtering, it is preferable that the 02 gas be introduced into the vacuum chamber by spraying it onto the substrate.

The preferred range of P(＾r+0°) in the present invention is l
X 10-' to I X 10-'' Torr, especially 5 X 10-' to 8 X 10-'' Torr.

Note that it is preferable to use RF sputtering as the sputtering method.

There is no particular limit to the power input for sputtering, but it is 0.2 to 2 kW.
It is particularly preferable to set it as 0.4-1.5kW.

For details on Fe5O4 thin film formation by direct method, see Journal of the Institute of Electronics and Communication Engineers '80/9 Vol, J63-CNo, 9 p.
, 609 to 616, and in the present invention, it is preferable to form the magnetic layer according to this, and at that time, it is preferable to perform sputtering at a partial pressure of 0□ as described above.

In addition, the indirect method uses Fe as a target to form α-Fe2e3 in an oxidizing atmosphere, and then reduces it to Fe5O.
This is the way to get 4.

Fe3O4 deposited by sputtering is γ-Fe2
Oxidized to O3.

This oxidation occurs at a partial pressure of 02 gas of about 0.05 to 0.8 atm.
The heat treatment may be carried out in an atmosphere with a total pressure of approximately 0.5 to 2 atmospheres (usually, heat treatment in the atmosphere is preferably carried out).

The holding temperature during heat treatment is 200 to 400°C, especially 25°C.
It is preferable that it is 0-350 degreeC. Further, the temperature holding time is preferably 10 minutes to 10 hours, particularly 1 hour to 5 hours.

Also, the heating rate is 3.5~b Especially 5.0~b Yes.

By performing heat treatment under these conditions, α-F
The depth of the existence region of e2e3 can be within the above range, and α
-The above-mentioned peak area ratio of FeJi can be easily obtained.

Note that the temperature increase rate may be constant, gradually increased or decreased, or a plurality of temperature increase rates may be combined to increase the temperature to the holding temperature.

The magnetic layer formed in this way has a coercive force of 400 to 2
Magnetic properties of 000 0e, residual magnetization 2000 to 3000G, and squareness ratio of about 0.55 to 0.85 are obtained, and α-Fe
There is almost no deterioration in magnetic properties due to the inclusion of 20s.

If necessary, Co, Ti, Cu, etc. may be added to the magnetic layer (Also, Ar, etc. contained in the film forming atmosphere may be contained).

The thickness of the magnetic layer is set at 50 mm in consideration of productivity, magnetic properties, etc.
It is preferable to set the number to about 0 to 3000 people.

Preferably, a lubricating film 4 is provided on such a magnetic layer 3.

The lubricating film preferably contains an organic compound, particularly an organic compound having a polar group, a hydrophilic group, or a hydrophilic portion.

There is no particular restriction on the organic compound used, and it may be liquid or solid, and fluorine-based organic compounds, such as European Patent Publication No. 0165650 and its corresponding Japanese application, JP-A-61-4727, , perfluoropolyethers as described in European Patent Publication No. 0165649 and its corresponding Japanese application, JP-A-61-155345, or various known fatty acids,
An appropriate one may be selected from various esters, various alcohols, etc.

There is no particular restriction on the method for forming the lubricating film, and a coating method or the like may be used.

The surface of the lubricating film has a contact angle with water of 70" or more, especially 90".
It is preferable that the temperature is at least .degree.

Having such a contact angle prevents the magnetic head from adhering to the magnetic recording medium.

The thickness of the lubricating film varies depending on the film forming method and the compound used, but is preferably about 4 to 300.

When the thickness is 4 Å or more, durability is improved, and when it is 300 Å or less, adsorption and crashes of the magnetic head are reduced. In addition,
A more preferable thickness is 4 to 100 people, and an even more preferable thickness is 4 to 80 people.

The magnetic recording medium of the present invention in which the magnetic layer having the peak ratio as described above is formed has a surface roughness (Rmax) on the magnetic layer side.
When the number of people is 50 to 200, the durability is further improved.
In this case, the more preferable range of Rmax is 80 to 150
The number of people is more preferably 80 to 120, particularly preferably 90 to 120.

If Rwax on the magnetic layer side is within the above range, not only the durability will be improved, but also recording and reproducing can be performed while keeping the distance between the medium surface and the floating surface of the floating magnetic head at 0.1 μm or less. Furthermore, there is no adhesion between the floating magnetic head and the magnetic recording medium, making high-density recording possible.

In addition, in order to obtain this higher Rwax on the magnetic layer side,
When oxidizing Fe504 to γ-Fe2O3 as described above, the heat treatment temperature and time may be controlled.

The magnetic recording medium of the present invention is effective when recording and reproducing is performed using a known composite floating magnetic head, monolithic floating magnetic head, etc., but is particularly effective when used in combination with a floating thin film magnetic head. If used,
Shows extremely high effectiveness.

FIG. 4 shows an example of a thin film floating type magnetic head which is a preferred embodiment of the magnetic head of the present invention.

The floating type magnetic head 10 shown in FIG.
and a protective layer 70 in this order. Further, if necessary, a !R synovial film similar to that described above may be provided on the front surface, that is, the floating surface, of such a floating magnetic head 10.

In addition, in the present invention, Rwax of the front surface is 200 Å.
Hereinafter, it is particularly preferable that the number of participants be 50 to 150 people. A magnetic head having such Ra+ax and the above-mentioned R
By using it in combination with a magnetic recording medium having +max, the effects of the present invention are further improved.

There is no particular restriction on the material of the coil layer 60, and a commonly used metal such as Al2 or Cu may be used.

There are no restrictions on the coil winding pattern or winding density.
(A known one may be selected and used as appropriate.) For example, the winding pattern may be a spiral type as shown, a laminated type, a zigzag type, or the like.

Further, the coil layer 60 may be formed using various vapor deposition methods such as sputtering.

The base body 20 may be made of a known material such as Mn-Zn ferrite.

When such a magnetic head is used for the magnetic recording medium of the present invention, the base body 20 has a Vickers hardness of 1000.
kgf/mm” or more, especially 100 C) to 3000 kg
It is preferable to be made of a ceramic material with a diameter of about f/mm2. With this configuration, the effects of the present invention become even more remarkable.

Ceramic materials with a Vickers hardness of 1000 kgf/rarI+'' or higher include ceramics whose main component is Al203-Tic, ceramics whose main component is ZrO□, ceramics whose main component is SiC, ceramics whose main component is AgN, and Zr01. -Ceramics whose main component is Ag20m, ceramics whose main component is Aggos-TiO□, ceramics whose main component is Zr0z-Carbide, or S l s N 4-
Ceramics containing Al203 as a main component are suitable.

These also contain Mg, Y, ZrOx as additives.
, TiO2, etc. may further be contained.

Among these, Al2
03-TiC-based ceramics or Zr
It is a ceramic whose main component is 0a.

Any conventionally known material can be used for the lower and upper magnetic pole layers 41, 45, such as permalloy, sendust, CO-based amorphous magnetic alloy, and the like.

The magnetic poles are usually provided as a lower magnetic pole layer 41 and an upper magnetic pole layer 45 as shown in the figure, and a gap layer 50 is formed between the lower magnetic pole layer 41 and the upper magnetic pole layer 4S.

The gap layer 50 may be made of a known material such as Ag-0- or 5iO-.

The patterns, film thicknesses, etc. of the pole layers 41, 45 and the gap layer 50 may be any known ones.

Furthermore, in the illustrated example, the coil layer 60 is of a so-called spiral type, and the upper and lower magnetic pole layers 41 are arranged in a spiral shape.
．． 45, and an insulating layer 33.35 is provided between the coil layer 60 and the upper and lower magnetic pole layers 41.45.

Further, an insulating layer 31 is provided between the lower magnetic pole layer 41 and the base body 20.

Any conventionally known material can be used for the insulating layer; for example, when a thin film is formed by sputtering, SiO2, glass, AQ*O-, etc. can be used.

Further, a protective layer 70 is provided on the upper magnetic pole 45 . As the material for the protective layer, any conventionally known material can be used, such as Al220. etc. can be used. Further, various resin coat layers or the like may be laminated thereon.

The manufacturing process of such a thin film type floating magnetic head usually consists of thin film formation and pattern formation.

As mentioned above, to create the thin films constituting each of the above layers,
A conventionally known vapor phase deposition method such as a vacuum evaporation method, a sputtering method, or a plating method may be used.

Pattern formation of each layer of the floating magnetic head can be performed by conventionally known selective etching or selective deposition. Wet etching or dry etching can be used as the etching.

Such a floating magnetic head is used in combination with a conventionally known assembly such as an arm.

To perform recording and reproducing using the magnetic recording medium of the present invention, particularly a magnetic disk, recording and reproducing are performed by making the magnetic head fly while rotating the disk.

The disk rotation speed is approximately 2000 to 6000 rpm, particularly 2000 to 4000 rpm.

In addition, the flying height can be set to 0.2- or less, particularly 0.15- or less, and even 0.1- or less, for example 0.01 to 0.09-, in which case good flying characteristics and C8S durability can be achieved. You can get sex.

The flying height is adjusted by changing the slider width and the load on the magnetic head.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

<Preparation of magnetic disk sample> An aluminosilicate glass substrate with an outer diameter of 130 mm, an inner diameter of 40 mm, and a thickness of 1.27 mm was polished and further subjected to chemical strengthening treatment. Chemical strengthening treatment is 450
This was done by immersing it in molten potassium nitrate at .degree. C. for 10 hours.

Next, the surface of this glass substrate was smoothed by mechanochemical polishing. A polishing liquid containing colloidal silica was used for mechanochemical polishing.

The surface roughness (Rmax) after polishing was 50 people.

After cleaning these glass substrates, a magnetic layer was formed on the surface of each glass substrate in the following manner.

First, preliminary sputtering is performed in an Ar gas atmosphere, and F
e The oxide film on the target surface was removed. Then 0□
A gas was introduced and reactive sputtering was performed to form a Fe1O+ film. Note that the 02 gas was introduced so as to be blown onto the substrate.

P (
Ar+Oil and P ox/P (Ar+Ozl are I x 10-” Torr and 0.058 Torr, respectively)
And so.

After forming the Fe5r film, oxidation was performed by heat treatment in the air under the conditions shown in Table 1 to obtain a γ-Fe2O3 magnetic layer.
Note that the thickness of the magnetic layer was 1000.

Table 1 shows Rwax on the magnetic layer side of each magnetic disk sample. Note that Rmax was measured using a stylus type surface roughness meter.

X-ray diffraction was performed on the magnetic layer of each sample to create an X-ray diffraction chart.

Note that X-ray diffraction was performed using the apparatus shown in FIG.

Table 1 shows the analysis results of the X-ray diffraction chart of each sample.

Further, the magnetic layer of each sample was polished by mechanochemical polishing using colloidal silica, and the presence of α-FeJs in the thickness direction of the magnetic layer was examined. In addition, X
For the line diffraction, a low incident angle X-ray diffractometer shown in FIG. 3 was used at β=2°.

For sample No. 014, the X-ray diffraction chart of the magnetic layer before polishing and the X-ray diffraction chart of the magnetic layer after polishing by 170 people are shown in FIGS. 5 and 6, respectively.

In FIG. 5, a peak of the plane index (104) of α-Fe2O3 is observed, but this peak is not observed in FIG.

For each sample, the surface index of α-Fe2O3 (104
) (7) Peak area P(104) and Y -FemOs
(7) Ratio of the surface index (311) to the peak area P(311) P(104)/The depth Dα when P(311) is equal to the peak area is shown in Table 1.

In addition, for sample Nos. 2 to 5, P(104)/P
(311) gradually decreased as polishing progressed. Therefore,
a-FeJs has P(104)/P(3
11) was confirmed to exist in the entire region up to the depth where it became zero.

Next, a lubricating film was formed on the magnetic layer of each sample.

The lubricating film was formed to a thickness of 20 mm using a 1 wt % O solution of a compound having a molecular weight of 2000 represented by the following formula by a spin code method. Contact angle of this lubricating film surface with water (30 seconds after dropping water)
was 10°.

(Formula) %Formula % Regarding the magnetic disk sample thus obtained, the sliding durability and reproduction output were measured by the following method. The results are shown in Table 1.

Magnetic head used: Vickers hardness 2200 kgf/mm2 Aj20.
- After forming a thin film magnetic head element on a TiC substrate, it was processed into a magnetic head shape and attached to a support spring (gimbal) to produce an air bearing type floating magnetic head.

The Rmax of this magnetic head floating surface was 130 people.

The slider width was 150 μm, and the gimbal load was 25 g.

(Sliding Durability) Using the above magnetic head, a sliding durability test was conducted at 25° C. and 50% relative humidity.

The above magnetic head was pressed against the magnetic disk sample, and the relative speed between the magnetic disk and the magnetic head was 20 m /
The magnetic disk was rotated so that At this time, it was confirmed by an AE (acoustic emission) sensor that the magnetic head was constantly sliding without floating.

Durability was evaluated based on the time until scratches appeared on the magnetic disk.

0: 60 minutes or more ○: 40 minutes or more and less than 60 minutes △: 20 minutes or more and less than 40 minutes ×: less than 20 minutes This sliding durability test is a more severe durability test method than the C3S durability test. .

1st Earthwork Measure the playback output for each sample shown in Table 1, α-
The reduction in reproduction output due to the inclusion of Fe2O3 was investigated.

The evaluation was performed on sample N011, which does not contain α-Fe2O3.
The reproduction output was set to 100, and ○: 95 or more and x: less than 95.

The effects of the present invention are clear from the results shown in Table 1.

That is, α-Fe203 is distributed from the surface of the magnetic layer by 50 to 2
The magnetic recording medium of the present invention, which falls within the range of up to 0.000, has a high durability of the magnetic layer, and also shows no deterioration in magnetic properties compared to a comparative sample that does not contain α-Fe203.

In addition, when a C8S durability test was conducted on each of the above samples, the same tendency as in the sliding durability test was observed.

<Effects of the Invention> According to the present invention, a magnetic recording medium with high durability, particularly C8S durability (and high magnetic properties) can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of the magnetic recording medium of the present invention. FIG. 2 is a schematic diagram of the X-ray diffraction apparatus. FIG. 3 is a schematic diagram of a low incidence angle X-ray diffraction apparatus. FIG. 4 is a partial sectional view of a magnetic head used in the present invention. FIG. 5 is an X-ray diffraction chart of the γ-Fe2Oim layer before polishing prepared using a low incident angle X-ray diffractometer. FIG. 6 is an X-ray diffraction chart of the polished γ-Fezes magnetic layer prepared using a low-incidence-angle X-ray diffractometer. Explanation of symbols 1... Magnetic recording medium 2... Substrate 3... Magnetic layer 4... Lubricating film 101... X-ray source 102... Magnetic recording medium 103... Counter DS...・Divergence slit SS...Scatter slit R5...Receiving slit MM...Monochromator SL, S2...Solar slit 10...Magnetic head Applicant: TDC Co., Ltd. Agent: Patent attorney Yo Ishii - same patent attorney 1) Tatsuya FIG, 1 FIG, 4 (by sdD) (/: 4# Q 0'゛ (sdzi)
'-1/:4114

Claims (1)

[Scope of Claims] (1) A magnetic recording medium having a continuous thin film type magnetic layer containing γ-Fe_2O_3 as a main component on a rigid substrate, wherein α is applied to a region from the surface of the magnetic layer to a depth of at least 50 Å. - A magnetic recording medium characterized in that -Fe_2O_3 is present and α-Fe_2O_3 is substantially absent in a region having a depth exceeding 200 Å. (2) In the X-ray chart obtained by performing X-ray diffraction while polishing or etching the magnetic layer, α-F
The peak area of the plane index (104) of e_2O_3 is P(1
04) and the peak area of the plane index (311) of γ-Fe_2O_3 is P(311), then P(104)/
2. The magnetic recording medium according to claim 1, wherein the depth at which P(311) becomes zero is 50 to 200 Å. (3) In the X-ray diffraction chart of the magnetic layer, α-F
The peak area of the plane index (104) of e_2O_3 is P(1
04), and the plane index of γ-Fe_2O_3 (311),
The peak areas of plane index (400) and plane index (222) are calculated as P(311), P(400) and P(2
22), then 0.02≦P(104)/P(311)≦0.200≦
The magnetic recording medium according to claim 1 or 2, wherein P(400)/P(311)≦1.0 0≦P(222)/P(311)≦0.5. (4) A magnetic recording and reproducing method for performing recording and reproducing by rotating the magnetic recording medium according to any one of claims 1 to 3 and floating a magnetic head above the magnetic recording medium, wherein the magnetic recording medium is A magnetic recording and reproducing method characterized in that the magnetic head is disk-shaped and has a flying height of 0.2 μm or less.