JPH08124141A - Magnetic recording medium and magnetic recorder using the same - Google Patents

Abstract

PURPOSE: To decrease medium noises and to enhance S/N by specifying the film thickness of nonmagnetic ground surface films to >=0.3 to <=10nm and specifying the coercive force of a magnetic head for recording and reproducing information to >=2.4 kilooersted. CONSTITUTION: Amorphous plating layers 22, 22' which consist of an Al-4wt.% alloy having an outside diameter of 95mm, a bore of 25mm and a thickness of 0.8mm and have a film thickness of 13μm are formed. The product Brxt of the total (t) of these alloy based magnetic layers and the residual magnetic flux density Br measured by impressing a magnetic field in the relative traveling direction of the magnetic head with a magnetic recording medium at the time of recording is specified to >=10 to <=60 gauss microns. The coercive force Hc of the magnetic recording medium measured by impressing the magnetic field in the direction described above is specified to >=2.4 kilooersted, by which the recording and reproducing of the high-density information of >=2 gigabits per square inch are made possible as well.

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 for information recording such as a magnetic disk, and more particularly to a magnetic recording medium having an areal recording density of 1 gigabit per square inch or more and suitable for high density information recording. Recording medium

[0002]

2. Description of the Related Art Conventionally, in a medium for in-plane magnetic recording in which magnetization is reversed in the in-plane direction for recording, a Co-based alloy magnetic thin film containing a ferromagnetic metal such as Co as a main component is used as a recording layer. . In order to enable higher density information recording, it is required to reduce medium noise and increase coercive force for this recording layer. As a Co alloy-based magnetic film having a relatively high coercive force, a Co-based alloy magnetic film containing Pt such as a Co—Cr—Pt system or a Co—Ni—Pt system is used as compared with a conventional Co—Cr—Ta system. Others, such as IEEE Trans, on Magn. , Vol. Two
7 (1991), P5280 (Reference 1).

In general, C is used to increase the coercive force.
{100} crystal plane of an alloy-based non-magnetic undercoating film containing r or Cr as a main component and a Co-based alloy-based magnetic thin film {11.
A method of making the (0) crystal plane parallel to the recording surface is disclosed in Japanese Patent Laid-Open No. 1-22.
According to Japanese Patent Application Laid-Open No. 0217 (Reference 2), a method of epitaxially growing the {10.0} crystal plane of a Co-based alloy magnetic thin film on the {110} crystal plane of an alloy-based nonmagnetic underlayer in parallel with the recording surface is described in US It is proposed by the specification of Japanese Patent No. 5082747 (Document 3) and the like. Further, as an effective method for reducing the medium noise, magnetically isolating the magnetic crystal grains by spatially separating the recording layer is described in, for example, IEEE Trans. on Mag
n. , Vol. 26, No. 5 (1990) p. 227
1-22276 (reference 4). Also, C
It is effective to reduce the magnetic crystal grain system by reducing the film thickness of the alloy non-magnetic underlayer film containing r or Cr as the main component, for example, IEEE Trans. on
Magn. , Vol. 29, No. 6 (1993) p.
3688-3690 (reference 5).

[0004]

To achieve higher density, for example, IEEE Trans. on M
agn. , Vol. 28 (1992) P3078-3
083 (reference 6), the coercive force Hc is increased in order to overcome the demagnetizing field from the magnetization of the bit boundary and hold the magnetization in the recording direction, and at the same time, the film thickness δ of the recording layer is increased. Of the residual magnetic flux density Br and Br. It is necessary to reduce δ to reduce the demagnetizing field. 2.4k to achieve recording density of 1 gigabits or more per square inch
It has been found that a coercive force exceeding Oe is required.

However, in practice, how to combine the recording / reproducing separated head using the magnetoresistive effect element and the above magnetic recording medium to realize a magnetic disk device having a high recording density is described. , Was not considered enough.

Further, according to the research conducted by the present inventors, in practice, when the thickness of Cr or an alloy-based non-magnetic underlayer containing Cr as a main component is reduced in order to reduce medium noise,
It was found that the coercive force Hc was lowered due to the deterioration of the crystallinity of the base film, and the density could not be increased. The inventors of the present invention have conducted further research, and as the thickness of the alloy non-magnetic underlayer is reduced, the coercive force Hc decreases to a certain point as described above, but beyond that. When the thickness was further reduced, it was found that there was a range in which a high coercive force Hc was exhibited again when an extremely thin underlayer was formed.

The present invention has been made in view of the above points, and an object of the present invention is to solve the above-mentioned problems of the prior art and to use a specially-structured base film to achieve 1 gigabits per square inch. An object of the present invention is to provide a high coercive force, low noise magnetic recording medium capable of recording and reproducing high-density information as described above. An additional object of the present invention is to provide a highly reliable magnetic recording device which is used in combination with the above high coercive force and low noise magnetic recording medium.

[0008]

In order to achieve the above object, the present invention provides an information based on an alloy magnetic thin film such as a Co-based alloy based on at least one nonmagnetic underlayer on a nonmagnetic substrate. A magnetic recording medium in which a recording layer is formed (a protective film of C, SiO2, ZrO2, etc., if necessary, and a lubricating film made of a polymer material is formed on the outermost surface thereof) has the following structure. Be prepared.

(1) The thickness of the non-magnetic underlayer is 0.3
It is characterized in that it is not less than 10 nm and not more than 10 nm. At this time, the thickness of the underlayer is preferably 0.5 nm or more and 2 nm or less. Furthermore, the nonmagnetic underlayer at this time is an alloy containing Cr and Ti as main components, and the information recording layer is Co, Cr and Pt. It is desirable that the film thickness of the alloy magnetic film and the underlayer film whose main component is 2 nm. With the above structure, a coercive force in the recording direction of 2.4 kOe or more can be obtained.

(2) The non-magnetic underlayer film formed on the non-magnetic substrate is made of a metal having an island-like structure in which the crystal grains have a grain size of 10 nm or less, and is an average measured by a fluorescent X-ray apparatus or the like. The characteristic film thickness is 0.1 nm or more and 10 nm or less. At this time, the thickness of the base film is preferably 0.5 nm or more and 2 nm or less. Further, the non-magnetic underlayer film at this time is made of Cr and Ti.
Containing Al as the main component, and the information recording layer having Co, Cr and P
It is desirable that the film thickness of the alloy magnetic film containing t as a main component and the underlayer film be 2 nm. Further, the grain size of the magnetic crystal grains of the alloy magnetic film is preferably 20 nm or less in order to achieve an areal recording density of 1 gigabit per square inch or more. With the above structure, the coercive force in the recording direction is 2.4k.
Oe or higher is obtained.

The non-magnetic underlayer is made of Cr, Ti, M.
o, W, V, Nb, Ta, Cu, Ag, Mn, Zr, H
It may be made of an alloy containing f or Si as a main component, and its film thickness is preferably 0.5 nm or more and 2 nm or less.

(3) In the information recording layer formed on the non-magnetic substrate via the non-magnetic underlayer, an alloy magnetic film containing Co, Cr and Pt, which are close-packed hexagonal lattice crystal structures, as main components, It is characterized in that the crystal grains of which the c-axis orientation is substantially parallel to the substrate surface and those of which the crystal grains are substantially perpendicular to the substrate surface coexist. At this time, the thickness of the base film is preferably 0.5 nm or more and 2 nm or less. Further, at this time, it is preferable that the non-magnetic undercoating film has an alloy containing Cr and Ti as main components, the information recording layer has an alloy magnetic film containing Co, Cr and Pt as main components, and the undercoating film has a thickness of 2 nm. . With the above structure, a coercive force in the recording direction of 2.4 kOe or more can be obtained.

In the magnetic head used in the magnetic recording apparatus combined with the magnetic recording medium of the above (1) to (3), a recording / reproducing element using a magnetoresistive element is used.
It must be a regenerative separation type head. The magnetic recording medium according to the above (1), (2) or (3) of the present invention has a recording density of, for example, 1 gigabits per square inch or more due to a combination with a high reproducing sensitivity which is a characteristic of the magnetoresistive effect element. Sufficient S / N can be obtained even when recording / reproducing. Further, the reproducing portion of the magnetic head is arranged between a plurality of conductive magnetic layers which cause a large resistance change due to a mutual change of their magnetization directions by an external magnetic field, and the conductive magnetic layers. A magnetic resistance sensor including a conductive non-magnetic layer, and a magnetic field is generated in the traveling direction of the magnetic head relative to the magnetic recording medium during recording and the total thickness t of the alloy magnetic layer. 1. The product Br × t with the residual magnetic flux density Br applied and measured is 10 gauss · micron or more and 60 gauss · micron or less, and the coercive force Hc of the magnetic recording medium measured by applying a magnetic field in the above direction is 2. By setting the distance to 4 kilo-oersted or more, it is possible to record and reproduce high-density information of 2 gigabits or more per 1 square inch.

[0014]

The operation based on the above configuration will be described.

The present inventors produced an in-plane magnetic recording medium by the following method and confirmed the above function. Various 3.5-inch magnetic disk substrates, such as Al-Mg alloy, chemically strengthened glass, and crystallized glass, whose surfaces were mirror-polished with Ni-P plated, were placed at a constant takt time of 30 seconds. The film was formed by the dc magnetron sputtering method in a single-wafer type sputtering apparatus in which the respective films constituting the magnetic recording medium are formed in separate film forming chambers while sequentially feeding the films one by one. Here, the film forming conditions are as follows: back pressure of main vacuum chamber: 5 × 10 −8 Torr or less, substrate temperature: 100 to 300
C, Ar gas pressure: 5 to 30 mTorr, input power: variously changed to 1 to 4 kW for a target size of 6 inches. C with a film thickness of 0.3 to 100 nm on the above various substrates
An alloy non-magnetic undercoating film mainly composed of r and Ti is formed, and further, Co, Cr and Ta or Co, Cr and Pt having various compositions with a film thickness of 10 to 40 nm are continuously formed.
An alloy magnetic film containing as a main component was formed, and a C protective film was formed thereon, and magnetic properties, crystallographic properties, recording / reproducing properties, etc. were evaluated. Recording / reproduction characteristics are measured with a thin film head and MR.
Evaluation was performed using a recording / reproducing separated head having a combined head. As a result, for example, the substrate temperature is set to 270 ° C., Cr-15 at% Ti is used as the base film, and the Ar gas pressure is 5
When the magnetic film is formed of Co-20 at% Cr-8 at% Pt with Ar gas pressure of 5 mTorr and input power of 1 kW, the magnetic film is formed with mTorr and input power of 4 kW.
Measurement was performed by applying a magnetic field in the relative traveling direction of the magnetic head for recording / reproducing information when the average film thickness of the underlayer film measured by a fluorescent X-ray device was changed to 0.1 to 100 nm. The change in coercive force Hc is shown in FIG.

FIG. 1 is a diagram showing the magnetic characteristics of the magnetic recording medium of the present invention. FIG. 1 (a) shows the coercive force with respect to a non-magnetic underlayer, and FIG. 1 (b) shows one of those in FIG. It is a figure which expands and shows a part. In FIG. 1, Hc decreases with a decrease in the film thickness of the base film, but increases at 2 nm and is 2.4 kOe or more. However, it was found that the coercive force decreased again when the film thickness of the base film was thinner than 2 nm, and had a peak at 2 nm. At this time, from the diffraction pattern obtained by the X-ray diffraction apparatus, it was found that Cr-1
Co-20 at% Cr-8 at% Pt which is considered to have been epitaxially grown on the {100} crystal plane of 5 at% Ti.
The {11.0} crystal plane of {circumflex over (1)} and the {00.1} crystal plane which is the closest packed plane of the closest packed hexagonal lattice crystal structure coexist. this is,
This is because the Cr-Ti alloy nonmagnetic underlayer film has an island-like structure in which crystal grains are dispersed. That is, when the film thickness of the base film is extremely thin, the ground film (substrate surface) is exposed in some places in the base film. Therefore, the alloy magnetic film formed on the non-magnetic undercoat film by sputtering and the alloy magnetic film formed directly on the substrate surface made of metal plating such as Ni-P coexist. When the substrate is amorphous, the Co-based alloy-based magnetic thin film having a close-packed hexagonal lattice crystal structure formed directly on it has a close-packed surface {00.
1} Crystal planes grow preferentially. In addition, the Co-based alloy thin film formed on the base film as described above is {11.0}
Crystal planes grow preferentially. Therefore, a crystal grain having a c-axis orientation substantially parallel to the substrate surface (a crystal lying sideways) and a crystal grain having a substantially vertical orientation (a crystal standing) are mixed. It was found that the coercive force remarkably increases when the crystal grains are mixed.

It has been conventionally known that when the thickness of the non-magnetic underlayer film is reduced, the crystal grains of the magnetic film are reduced and the medium noise is reduced. The minimum thickness of the film is at most about 30 nm
However, various characteristics have not been sufficiently confirmed when the thickness is 30 nm or less. The inventors of the present invention further reduced the thickness of the non-magnetic underlayer film to 30 nm or less, so that as shown in FIG. 1, FIG. 5, FIG.
It was found and confirmed that a high coercive force and a low S / N can be obtained at a film thickness of 0.3 nm or more and 10 nm or less. Such an ultra-thin film thickness is
This includes cases where the atomic size level is less than a few atoms.

More specifically, the medium noise Nd can be reduced by reducing the thickness of the non-magnetic underlayer film to about 10 nm or less as shown in FIG. In addition, the coercive force Hc sharply decreases to 10 nm when the thickness of the underlayer film becomes 30 nm or less as shown in FIG. As Hc decreases, the 2f output E2f of the medium decreases as shown in FIG. For example, areal recording density 1 Gbit /
150kBP linear recording density required to achieve in2
The S / N of the medium at I was not improved due to the decrease of E2f when the thickness of the underlayer film was 50 nm or less. However,
According to the present discovery by the present inventors, the thickness of the base film is 2
Since the Hc greatly increased at nm, the S / N higher than the conventionally obtained value as shown in FIG. 7 was obtained due to the synergistic effect with the low Nd. As described above, the fact that a reduction that has not been found in the past was discovered is due to a detailed study of the above-described base film that is extremely thin as compared with the conventional one.

[0019]

Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

FIG. 2 schematically shows the sectional structure of the in-plane magnetic recording medium according to the present invention. In the figure, reference numeral 21 is a substrate made of Al-Mg alloy, chemically strengthened glass, crystallized glass, titanium, silicon, carbon or ceramics, and 22 and 22 'are Ni-P and Ni- formed on both surfaces of the substrate 21. It is a non-magnetic plating layer made of WP or the like. When an Al-Mg alloy is used as the substrate, one having such a plating layer is used as the substrate. 23 and 23 'are non-magnetic underlayer films made of Cr, Mo, W, or an alloy containing Cr, Mo, W as a main component, and 24 and 24' are Co-layers formed on the underlayer film. Sm, Co-Ni-Cr, Co-Ni-Pt,
Co-Ni-P, Co-Cr-Ta, Co-Cr-P
t, Co-Cr-W, Co-Cr-Si, Co-Cr-
Co-based alloy-based alloy magnetic film made of Ta-Pt or the like, 2
Reference numerals 5 and 25 'denote nonmagnetic protective films formed on the magnetic film and made of carbon, boron, SiO2, ZrO2 and the like.

Example 1 Outer diameter 95 mm, inner diameter 25 m
m, a 0.8 mm thick Al-4 wt% Mg alloy, on both sides of a disk substrate 21 made of Ni-12.5 wt% P and having a film thickness of 13 μm.
2'formed. A texture was formed on the surface of the non-magnetic substrate in a substantially circumferential direction by lapping and subsequent tape polishing. After that, stains such as abrasives adhered to the substrate were washed and removed and dried. The substrate thus formed is loaded into the substrate preparation chamber of the above-mentioned single-wafer dc magnetron sputtering apparatus and evacuated, and then the substrate is heated, the non-magnetic undercoat film formation chamber, the magnetic film formation chamber, and the non-magnetic protection. The film forming chamber and the take-out chamber are transferred in this order through a main exhaust tank having a vacuum degree of 4 × 10 and a minus 8th power Torr or less,
Each film was formed in each chamber. First, heating to 270 ° C. in the heating chamber, applying a power of 1 kW to a Cr target under an argon pressure of 5 mTorr to obtain a film thickness of 1
Cr underlayer films 23 and 23 'having a thickness of 0 nm were formed. On this underlayer film, under the argon pressure of 5 mTorr, 1 kW of electric power was applied to the target to produce Co-16 at% Cr-6.
Alloy magnetic films 24 and 2 made of at% Ta and having a film thickness of 27 nm
4'was laminated. In addition, 6mTor on this magnetic film
Power of 2 kW was applied to the target under an argon pressure of r to form carbon protective films 25 and 25 'having a film thickness of 10 nm. Then, a lubricating layer of adsorbent perfluoropolyether or the like was formed on the protective film to obtain a 3.5-inch magnetic disk.

Example 2 In Example 1, the composition of the non-magnetic underlayer film was Cr-15 at% Ti, the composition of the alloy magnetic film was Co-20 at% Cr-12 at% Pt, and the magnetic film of Example 1 was used. In order to make the product Br · δ of the recording layer thickness δ and the residual magnetic flux density Br approximately the same, a magnetic disk was formed by the same method as in Example 1 except that the thickness of the magnetic film was 23 nm. did.

Example 3 A magnetic disk was formed in the same manner as in Example 2 except that the thickness of the nonmagnetic underlayer film was changed to 2 nm.

<Embodiment 4> In Embodiment 1, the surface of the non-magnetic substrate is mirror-polished to have a surface roughness of about 1 nm by lapping to form an ultra-smooth substrate, and dirt such as an abrasive adhered to the substrate is washed. Removed and dried. Using the substrate thus formed, a magnetic disk was formed in the same manner as in Example 3.

Comparative Example 1 A magnetic disk was formed in the same manner as in Example 2 except that the thickness of the non-magnetic underlayer film was changed to 15 nm.

The magnetic characteristics and recording / reproducing characteristics of the magnetic disk thus formed were evaluated. The magnetic characteristics of the magnetic disk are 8 mm x 8 m from the position where the radius is 34 mm.
A sample was cut out into a substantially square shape of m and the magnetic film on one side was scraped off, and the maximum applied magnetic field was measured with a vibrating sample magnetometer at 10 kOe. In addition, the recording / reproducing characteristics were evaluated by using a magnetic head and recording with a gap length of 0.4 μm.
m, track width 3.0 μm, thin-film head with 30 windings, reproducing shield spacing 0.3 μm, track width 2.6
A recording / reproducing separated type head, which was an MR head of μm, was used. The magnetic gap between the magnetic head and the magnetic recording medium at the time of recording / reproducing was set to 0.07 μm, and the S / N values at the output half recording density (D50) and the linear recording density of 150 kBPI were obtained. As shown in Table 1, in Example 4 above, the coercive force was 2.7 kOe or more in the circumferential direction, and Comparative Example 1
On the other hand, a magnetic disk having a large S / N of 100 Oe or more and a S / N of 1.88 or more was obtained.

[0027]

[Table 1]

Example 5 Example 5 will be described with reference to FIG. 3 showing a cross section of an in-plane magnetized magnetic recording medium. Outer diameter 6
Al-7 with 5mm, inner diameter of 20mm and thickness of 0.635mm
Ni on both sides of the disk substrate 31 made of a Mg% alloy by weight.
Amorphous plating layers 32 and 32 'made of -12.5 wt% P and having a film thickness of 10 μm were formed. After forming a substrate in the same manner as in Example 1 and loading it in the substrate preparation chamber of the above-mentioned single-wafer dc magnetron sputtering apparatus and drawing a vacuum,
The substrate is heated to a non-magnetic underlayer film forming chamber, a first magnetic film forming chamber, a non-magnetic intermediate film forming chamber, a second magnetic film forming chamber, a non-magnetic protective film forming chamber, and a take-out chamber in this order at a vacuum degree of 4 × 10. Each film was formed by transporting it through a main exhaust tank having a minus 8th power Torr or less. First, 27 in the heating chamber
Heat to 0 ° C and Cr under an argon pressure of 5 mTorr
Apply 4 kW of power to the target to obtain a 10 nm thick C film.
r Underlayer films 33 and 33 'were formed. On this base film,
Target 1kW under argon pressure of 5mTorr
Power of Co-16at% Cr-6at% Ta
The first alloy magnetic films 34 and 34 'having a film thickness of 20 nm are laminated. On this magnetic film, a target of 1 kW of electric power was applied under an argon pressure of 5 mTorr to stack non-magnetic intermediate films 35 and 35 ′ made of Cr and having a thickness of 2 nm, and further on this intermediate film. By applying electric power of 1 kW to the target, the second alloy magnetic films 36 and 36 'made of Co-16 at% Cr-6 at% Ta and having a film thickness of 20 nm were laminated. Furthermore, a power of 2 kW was applied to the target on the magnetic film under an argon pressure of 6 mTorr to obtain a film thickness of 1
Carbon protective films 37 and 37 'having a thickness of 0 nm were formed. Then, a lubricating layer such as an adsorbent perfluoropolyether was formed on the protective film to obtain a 2.5-inch magnetic disk.
Here, although the first magnetic film and the second magnetic film have the same composition, they do not necessarily have to have the same composition. This Example 5
When the recording / reproducing characteristics of the magnetic disk of No. 1 were evaluated by the same method as described above, the S / N was 1.42 and
A high S / N was obtained by comparison.

Sixth Embodiment A magnetic disk having the same characteristics as in the fourth embodiment is used, a CoTaZr alloy is used as a recording magnetic pole material, and a composite magnetic head having a magnetoresistive effect element for reproduction is used. A recording device was prototyped. As shown in the schematic plan view of FIG. 4A and the schematic cross-sectional view of FIG. 4B, the present apparatus includes one or a plurality of magnetic disks 4
1, a composite head 43 for electromagnetic induction type recording and magnetoresistive effect element (MR) reproduction corresponding to the number of magnetic disks, a drive section 42 for rotationally driving the magnetic disk, a drive means 44 for the magnetic head, and the like. The magnetic disk device has a well-known configuration. As described above, by combining the magnetic recording medium according to the present invention with the magnetic disk device having the MR head and the high-accuracy head positioning device, the recording / reproducing error rate is 10 at the areal recording density of 1.5 gigabits per square inch. The characteristic of less than minus eight power was obtained. In this embodiment, the case of using the composite type magnetic head using the CoTaZr alloy as the magnetic pole material has been described, but the same effect is also obtained when using the composite type magnetic head using the recording magnetic pole material of NiFe, FeC alloy or the like. Is obtained.
Further, by configuring the reproducing portion of the magnetic head by a magnetoresistive sensor utilizing a giant magnetoresistive effect which is significantly larger than the conventional magnetoresistive effect, recording at a high areal recording density of 2 gigabits or more per square inch. The characteristic that the reproduction error rate is 10 −8 or less was obtained.

As the non-magnetic substrate, a substrate made of chemically strengthened glass, crystallized glass, titanium, silicon, carbon, ceramics or the like may be used. In this case, the non-magnetic plating layer may not be formed.

The present invention can be carried out in the following modes.

(1) In any one of claims 1 to 4, the thickness of the nonmagnetic underlayer film is 0.5 nm or more and 2 nm or less.

(2) In any one of claims 1 to 4, the nonmagnetic underlayer film is an alloy containing Cr and Ti as main components, and the information recording layer is an alloy magnetic film containing Co, Cr and Pt as main components.

(3) In any one of claims 1 to 4 or the above embodiments (1) to (2), the coercive force Hc measured by applying a magnetic field in the relative traveling direction of the magnetic head for recording and reproducing information is It is more than 2.4 kilo Oersted.

(4) In any one of claims 1 to 4 or the above embodiments (1) to (3), the alloy magnetic film is at least 1
It is formed of a multi-layer film divided by a non-magnetic intermediate film having at least one layer.

(5) A combination of the magnetic recording medium according to any one of claims 1 to 4 or the above-mentioned embodiments (1) to (3) and a recording / reproducing separated type magnetic head using a magnetoresistive effect element as a reproducing element. To use.

[0037]

As described in detail above, according to the present invention, an information recording layer of an alloy type magnetic film such as a Co-based alloy type is formed on a nonmagnetic substrate through at least one nonmagnetic underlayer film. In the known magnetic recording medium, the coercive force of the information recording layer is increased to, for example, 2.4 kilo Oersted or more and the medium noise is reduced by setting the thickness of the non-magnetic underlayer film to 0.3 nm to 10 nm. As a result, an S / N is increased, and an in-plane magnetic recording medium capable of recording an extremely high areal recording density of 1 gigabit per square inch or more can be obtained.

[Brief description of drawings]

1A and 1B are a diagram showing a magnetic characteristic of a magnetic recording medium of an example of the present invention and an enlarged diagram of a range of a thickness of a non-magnetic underlayer film, respectively.

FIG. 2 is a sectional view of an in-plane magnetic recording medium of one embodiment of the present invention.

FIG. 3 is a sectional view of an in-plane magnetic recording medium according to an embodiment of the present invention.

4A and 4B are a schematic plan view of a magnetic memory device according to an embodiment of the present invention and AA ′ thereof, respectively.
It is sectional drawing.

FIG. 5 is a diagram showing 2f output characteristics of a magnetic recording medium according to an example of the present invention.

FIG. 6 is a diagram showing medium noise of the magnetic recording medium of the example of the present invention.

FIG. 7 is a diagram showing S / N characteristics of the magnetic recording medium of the example of the present invention.

[Explanation of symbols]

 21 non-magnetic substrate 22, 22 'non-magnetic plating layer 23, 23' non-magnetic underlayer film 24, 25 'alloy magnetic film 25, 25' non-magnetic protective film 31 non-magnetic substrate 32, 32 'non-magnetic plating layer 33, 33 'Non-magnetic underlayer film 34, 34' First alloy magnetic film 35, 35 'Non-magnetic intermediate film 36, 36' Second alloy magnetic film 37, 37 'Non-magnetic protective film 41 Magnetic disk 42 Magnetic disk drive system 43 Magnetic head 44 Magnetic head drive system

Front page continuation (72) Inventor Yakuo Yaku 2880 Kozu, Odawara-shi, Kanagawa Hitachi Storage Systems Division (72) Inventor Akira Kato 2880 Kozu, Odawara, Kanagawa Hitachi Storage Systems Business In-house (72) Inventor Shioji Fujita 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (6)

[Claims] 1. A magnetic recording medium in which an information recording layer of an alloy-based magnetic film such as a Co-based alloy-based film is formed on a non-magnetic substrate with at least one non-magnetic underlayer film interposed therebetween. The thickness of the ground film is 0.3 nm or more, 10
Coercive force Hc of less than nm and measured by applying a magnetic field in the relative traveling direction of the magnetic head for recording / reproducing information
Is a magnetic recording medium having a magnetic field density of 2.4 kilo Oersted or more. 2. The non-magnetic underlayer is Cr or Cr
3. An alloy containing as a main component.
3. The magnetic recording medium according to claim 1. 3. The non-magnetic base film is Cr, Ti, M
o, W, V, Nb, Ta, Cu, Ag, Mn, Zr, H
The magnetic recording medium according to claim 1, which is made of an alloy containing f or Si as a main component and has a film thickness of 0.5 nm or more and 2 nm or less. 4. A magnetic recording medium comprising a non-magnetic undercoating film formed on a non-magnetic substrate, and an information recording layer comprising an alloy-based magnetic film such as a Co-based alloy-based film formed on the non-magnetic undercoating film. The magnetic recording medium is characterized in that the crystal grains are made of a metal having a dispersed island structure, and the average film thickness measured by a fluorescent X-ray device or the like is 0.1 nm or more and 10 nm or less. . 5. A magnetic recording medium in which an information recording layer of an alloy magnetic film such as a Co-based alloy system is formed on at least one nonmagnetic underlayer film on a nonmagnetic substrate,
The information recording layer is composed of an alloy-based magnetic film having a close-packed hexagonal lattice crystal structure, and the crystal grains of which the c-axis direction is substantially parallel to the substrate surface and those which are substantially perpendicular to the substrate surface are mixed. A magnetic recording medium characterized by: 6. A magnetic recording apparatus comprising a magnetic recording medium according to claim 1 and a magnetic head for recording / reproducing information on / from the magnetic recording medium, the recording unit and the reproducing unit. The reproducing portion of the magnetic head has a plurality of conductive magnetic layers whose magnetic directions change relative to each other due to an external magnetic field, thereby causing a large resistance change, and a conductive non-magnetic layer disposed between the conductive magnetic layers. And a magnetic field is applied in the traveling direction of the magnetic head relative to the recording medium at the time of recording and the total thickness t of the alloy-based magnetic layer. The product Br × t of the residual magnetic flux density Br is 10 Gauss · micron or more and 60 Gauss · micron or less, and the coercivity of the magnetic recording medium measured by applying a magnetic field in the relative traveling direction of the magnetic head. Hc of the magnetic recording apparatus, characterized in that 2.4 kOe or more.