JPH11154320A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which is suitable for high- density recording by lowering the noise of the recording medium. SOLUTION: A ground surface layer 2 consisting of Cr, etc., is formed on a glass substrate 1 and a magnetic layer 3 is formed on this ground surface layer 2 by simultaneously sputtering a magnetic material and a nonmagnetic material which does not solutionize with this magnetic material in an atmosphere having a pressure of 30 to 75 mTorr. The magnetic layer 3 include the clusters formed by flocculation of magnetic particles of 5 to 20 nm in grain size and the nonmagnetic material existing between the clusters. The average intervals between the clusters are 1.5 to 5 nm. The magnetic recording medium which provides a good SN ratio and is suitable for high-density recording is thus obtd.

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 large-capacity, high-recording-density magnetic recording / reproducing apparatus and a method of manufacturing the same.

[0002]

2. Description of the Related Art At present, magnetic recording / reproducing apparatuses have tended to have high recording densities in order to realize a small size and a large capacity. In the field of hard disk drives, which are typical magnetic recording devices, devices having a surface recording density exceeding 1 Gbit / in ² have already been commercialized, and it is expected that a 10 Gbit / in ² device will be put into practical use in a few years. Rapid technological progress is recognized.

[0003] The technical background that has made it possible to achieve such a high recording density is an improvement in medium performance and head-disk interface performance, and an increase in linear recording density due to the emergence of new signal processing methods such as partial response. Can be However, in recent years, the trend of increasing the track density has greatly exceeded the trend of increasing the linear recording density, which is a major factor in improving the areal recording density. This is attributable to the practical use of a magnetoresistive element type head (MR head) having much better reproduction output performance than the conventional induction type magnetic head. At present, it is possible to reproduce a signal having a track width of only several μm with a good SN ratio by using a magnetoresistive element type head. In the near future, it is expected that the head performance will be further improved and the track pitch will reach the submicron range.

When a signal is reproduced by an MR head,
Compared with the conventional inductive magnetic head, the influence of the noise of the recording medium on the reproduction signal is greater. Therefore, it is more important to reduce the medium noise. In order to realize such low noise, it is effective to make the crystal of the magnetic layer finer and to separate the magnetic particles.

Conventionally, as a method of accelerating the separation of magnetic particles, for example, a CoCrPt-based magnetic layer is heated at a substrate temperature of 30 ° C.
A method of performing sputtering at a high temperature of 0 ° C. or higher is known. According to this method, atoms sputtered to the substrate by sputtering can easily move on the substrate. As a result, a magnetic layer composed of CoPt-based magnetic crystal grains and a Cr-rich nonmagnetic material at the grain boundaries of the magnetic crystal grains is formed. When the nonmagnetic material is formed at the grain boundary, the separation of the magnetic crystal grains is promoted.

[0006]

However, in the method of promoting the movement of Cr to the grain boundary by heating the substrate,
Since the atoms that have reached the substrate easily move, the size of the magnetic crystal grains also increases, making it difficult to miniaturize the grains. Larger crystal grains are disadvantageous for reducing medium noise. Therefore, an object of the present invention is to provide a magnetic recording medium in which medium noise is reduced and suitable for high-density recording, and a method for manufacturing the same.

[0007]

In order to achieve the above object, a magnetic recording medium according to the present invention comprises a non-magnetic substrate, an underlayer formed on the non-magnetic substrate, and a non-magnetic substrate formed on the non-magnetic substrate. The magnetic layer has a particle size of 5 nm to 2 nm.
It includes clusters in which magnetic particles each having a diameter of 0 nm (preferably 8 nm to 10 nm) are aggregated, and a non-magnetic substance existing between the clusters.
The thickness is 5 nm to 5 nm.

In such a magnetic recording medium, clusters in which magnetic particles having a small particle diameter are aggregated are dispersed in a state separated by a non-magnetic material, so that medium noise is suppressed and a magnetic recording medium exhibiting a high SN ratio is obtained. Medium can be obtained. Here, the average interval between clusters means an average value of the shortest distances of adjacent clusters.

[0009] Such a magnetic recording medium can be obtained by the following method. That is, the method for manufacturing a magnetic recording medium of the present invention includes a step of forming a base layer on a non-magnetic substrate and a step of forming a magnetic layer on the base layer, wherein the magnetic layer has a thickness of 30 to 75 mtorr. A magnetic material and a non-magnetic material that does not form a solid solution with the magnetic material are simultaneously sputtered in an atmosphere having a pressure.

When a magnetic material and a non-magnetic material that do not form a solid solution with each other are simultaneously sputtered in an atmosphere having a relatively high pressure, clusters in which fine magnetic particles are aggregated are formed, and separation of the clusters is promoted. Is done.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of one embodiment of the magnetic recording medium of the present invention. As shown in FIG. 1, the magnetic recording medium includes a glass substrate 1, an underlayer 2,
It has a structure in which a magnetic layer 3 and a protective film 4 are sequentially formed, and a lubricant is further applied thereon to form a lubricant layer 5. Aluminosilicate glass or the like can be used as the glass constituting the glass substrate 1. The underlayer 2 is made of a nonmagnetic material containing NiAl, Cr, or the like, but Cr or a Cr alloy can be suitably used. The protective layer 4 is made of, for example, carbon. The glass substrate 1, the base layer 2, the protective layer 4, and the lubricating layer 5 can be used without any particular limitation on conventionally used materials. The thickness of the base film is not particularly limited, but is preferably 50 nm to 200 nm.

Hereinafter, the magnetic layer 3 will be described. The magnetic layer includes clusters 6 of magnetic particles and grain boundary substances 7 between the clusters. As shown schematically in FIG. 2, it is preferable that the grain boundary of the cluster is not densely filled with the grain boundary material 7 and the grain boundary material 7 and the void 8 exist. Such a structure can be formed by relatively increasing the pressure of the atmosphere during sputtering, as described later.

Each of the clusters 6 has an average diameter of, for example, 20 nm to 50 nm and is 1.5 nm to 5 nm from each other.
Are dispersed in the magnetic layer 3 so as to maintain the average spacing of. Although the cluster 6 is shown as one particle in FIG. 2, it is actually an aggregate of fine magnetic particles. The magnetic particles constituting the cluster are 5 nm
It has a particle size of ２０20 nm, more preferably 8 nm〜１０10 nm. The magnetic particles constituting the cluster are densely aggregated with each other (for example, at intervals of about 1 nm). The thickness of the magnetic layer is not particularly limited, but is preferably 20 nm or less.

The material constituting the magnetic particles is not particularly limited, but a CoPt-based alloy can be suitably used. On the other hand, the grain boundary material is composed of a non-magnetic material. The nonmagnetic material is at least one metal compound (metal oxide and metal oxide) selected from silicon oxide, aluminum oxide, cobalt oxide, titanium oxide, chromium oxide, magnesium oxide, tantalum oxide, silicon nitride, aluminum nitride, titanium nitride, and chromium nitride. And / or metal nitride).

In the magnetic layer, the metal component of the metal compound forming the nonmagnetic material is 5 to 1 with respect to the total amount of the metal component forming the magnetic material and the metal component forming the nonmagnetic material.
Preferably it is 2.5 atomic%. This is because good electromagnetic conversion characteristics can be obtained within this range.

As shown in FIG. 4, the magnetic layer 3 may not be a single layer but may be a multilayer film in which a magnetic thin film 11 and a non-magnetic thin film 12 are laminated. With such a laminated structure, medium noise can be further reduced. In this case, the thickness of the nonmagnetic thin film 12 is preferably set to 1 to 5 nm. The thickness of the entire magnetic layer is preferably 20 nm or less as in the case of a single layer. In this case, as the non-magnetic thin film, Cr or a Cr alloy (for example, CrV, C
rMo) can be used.

Further, the magnetic recording medium of the present invention can obtain good characteristics without applying so-called zone texture. In order to realize high-density recording, it is advantageous that the flying height of the head is small. Therefore, conventionally, the surface roughness of a disk substrate in a hard disk device is 0.5 n.
m or less. However, if the surface is smooth, the head is attracted to the magnetic disk at the time of contact start / stop (CSS) of the head, so that a texture is formed by roughening a part of the surface of the magnetic disk (zone texture). Normal,
When the entire surface of the disk is roughened, the flying height of the head is increased and the electromagnetic conversion characteristics are reduced. However, since the magnetic recording medium of the present invention has good electromagnetic conversion characteristics, it is possible to compensate for the deterioration of the electromagnetic conversion characteristics due to the overall roughness of the medium surface. For example, if the magnetic recording medium is formed using a glass substrate having a surface roughness of 1 nm to 1.6 nm, high-density recording can be realized without taking measures against head adsorption such as zone texture. Become.

The surface roughness (Ra) in this specification
Is defined from the description of JIS B0601.

The magnetic recording medium of the present invention can be formed by using a sputtering method as conventionally practiced. When the sputtering method is applied, the magnetic layer 3 having the above-described structure is formed in an atmosphere having a relatively high pressure (preferably 30 mTorr to 75 mTorr).
Under a gas pressure), a magnetic material and a non-magnetic material are simultaneously sputtered. The magnetic substance and the non-magnetic substance may be prepared as separate targets, or a mixture of both may be prepared as the target.

The gas pressure at the time of sputtering the magnetic layer affects the structure of the magnetic layer, particularly the structure between clusters of magnetic particles. As the gas pressure decreases, the gap existing between the clusters tends to decrease. For example, when the magnetic layer shown in FIG. 2 is formed with a reduced gas pressure, a magnetic layer having a structure in which a non-magnetic substance is filled between the clusters 6 is obtained as schematically shown in FIG. Compared with the magnetic layer shown in FIG. 2, the magnetic layer shown in FIG. 3 has a smaller cluster interval and a smaller degree of separation.

In order to sufficiently separate the clusters, the gas pressure is preferably 30 mTorr or more. On the other hand, if the gas pressure is too high, the magnetic layer becomes sparse, and there is a possibility that scratches may occur due to contact with the head during CSS. Therefore, the gas pressure is preferably 30 mTorr to 75 mTorr as described above.

The substrate temperature for forming the magnetic layer is preferably 200 ° C. or lower. Substrate temperature is 200 ℃
This is because, when the value exceeds 3, magnetic particles and clusters are joined to each other, which is disadvantageous for lowering the noise of the recording medium.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention. A disk-shaped glass substrate having a diameter of 2.5 inches is placed in an in-line sputtering apparatus, and the inside of the apparatus is evacuated to a vacuum of the order of 10 ^-6 torr. Baking for minutes. After baking, the substrate temperature is room temperature (about 25 ° C, the same applies hereinafter)
Cooled down to return. The degree of vacuum after cooling was 5 × 1
It was 0 ^-7 torr.

A Cr layer is formed as a base layer on a glass substrate so as to have a thickness of 100 nm by an in-line sputtering apparatus, and a Cr layer is formed thereon at a predetermined substrate temperature and a predetermined gas pressure.
The magnetic layer was formed to have a thickness of about 15 nm. The sputtering target for forming the magnetic layer includes C
An oPt target having a suitable amount of SiO ₂ chips disposed thereon was used. The amount of SiO ₂ chips is
The amount of atoms was determined to be 10% of the total amount of Co atoms, Pt atoms, and Si atoms. The amount of each metal atom in the magnetic layer was measured by ICP emission spectroscopy.

Further, a carbon layer having a thickness of about 10 n was formed as a protective layer on the magnetic layer by the same sputtering method.
m. A lubricant was applied on the carbon layer. In the above film formation, argon (Ar) is used.
This was carried out in an inert atmosphere using The saturation magnetization (Msδ) of the magnetic disk manufactured under the above conditions is about 1
memu / cm ² .

The gas pressure and the substrate temperature greatly affect the characteristics of the magnetic recording medium. Therefore, in the above method, first, a magnetic layer was formed under various Ar gas pressures of 10 to 100 mTorr, and the relationship with the electromagnetic conversion characteristics was investigated. At this time, the substrate temperature was room temperature. Fig. 5 shows the results.
And FIG.

As shown in FIG. 5, from 10 mTorr to Ar
As the gas pressure was increased, the coercive force and the squareness ratio tended to decrease. The decrease in the squareness ratio is one of the phenomena indicating that the separation of the magnetic particles is promoted. In addition, as shown in FIG. 6, as the Ar gas pressure increased, the medium noise decreased and the SN ratio improved. Ar gas pressure is 3
If it is less than 0 mTorr, the reduction of the SN ratio becomes remarkable. On the other hand, if the Ar gas pressure exceeds 75 mTorr, the magnetic layer itself may become sparse and the medium may be damaged during CSS by the head. Also, as shown in FIG. 6, the SN ratio starts to decrease sharply when the gas pressure falls below about 40 mTorr.
Therefore, the gas pressure is preferably 30 mTorr to 75 mTorr,
More preferably, the pressure is 40 mTorr to 75 mTorr.

It should be noted that the SN ratio and the noise in this embodiment are the results of a relative evaluation with a predetermined target value being 0. Further, in the present embodiment, the magnetic characteristics were evaluated by a vibration sample magnetometer (VSM), and the electromagnetic conversion characteristics were 120
It was evaluated by kfci (flux changes per inch).

Next, the influence of the substrate temperature was investigated. In the above method, the Ar pressure is set to 50 mTorr, and the substrate temperature is set to:
Room temperature, 150 ° C, 200 ° C, 300 ° C or 350 ° C. As a result, as shown in FIG. 7, the SN ratio of the obtained disk tended to decrease monotonically as the substrate temperature increased. This is due to the rise in substrate temperature
This is probably because the growth of the magnetic crystal is promoted and the contact between the crystals is promoted, so that the medium noise increases. Therefore, the substrate temperature when forming the magnetic layer is 200
C. or less is preferred.

Further, the influence of the components of the magnetic layer was investigated.
C in the step of forming the magnetic layer in the above manufacturing method
Various discs were produced in the same manner as described above, except that the amount of SiO ₂ chips on the oPt target was changed. At this time, the Ar pressure was 50 mTorr and the substrate temperature was room temperature. The results are shown in FIGS. As shown in FIG. 8, the coercive force (Hc) gradually increases as the ratio of Si atoms in the magnetic layer (Si / (Co + Pt + Si)) increases, but the ratio of Si atoms decreases around 9%. To go. On the other hand, as shown in FIG. 9, the medium noise decreases as the ratio of Si atoms increases.

As is apparent from FIGS. 8 and 9, Si
If the amount is less than 5 atomic%, the coercive force becomes 2000 Oe or more, but a sufficient SN ratio cannot be obtained. On the other hand, when the amount of Si is 1
If it exceeds 2.5 atomic%, satisfactory values of both coercive force and SN ratio cannot be obtained. Therefore, the Si in the magnetic layer
The amount (metal content of the nonmagnetic material) is preferably 5 to 12.5 atomic% of the metal content of the magnetic layer (the total of the metal content of the nonmagnetic material and the metal content of the magnetic particles).

Incidentally, Si also has an effect of suppressing the grain growth of the magnetic particles, and is considered to contribute to the suppression of the particle size of the magnetic particles.

The state of the magnetic layer was measured using a scanning electron microscope (SE).
The results observed in M) are shown in FIGS. FIG.
Are: substrate temperature: room temperature, Ar pressure: 50 mTorr, Si amount: 1
FIG. 11 shows the result of observing the magnetic layer produced under the condition of 0 atomic%. FIG. 11 shows the result of observing the magnetic layer produced under the same condition as the magnetic layer of FIG. 10 except that the amount of Si was set to 0 atomic%. FIG. 12 shows the results obtained by observing the magnetic layer manufactured under the same conditions as the magnetic layer of FIG. 10 except that the substrate temperature was set to 300 ° C.

From a comparison between FIG. 10 and FIG. 11, it can be confirmed that the individual magnetic substances are clearly separated by simultaneously sputtering the non-magnetic substance SiO ₂ . Thus, a non-magnetic material such as SiO ₂ has an effect of promoting the separation of the magnetic material. On the other hand, as is clear from FIG.
If the substrate temperature is too high, the magnetic particles will be partially connected,
It can be confirmed that the particle size of the magnetic material increases.

Further, the results of observing the magnetic layer shown in FIG. 10 with a transmission electron microscope (TEM) are shown in FIGS. 13 and 14. From these TEM photographs (especially FIG. 13),
It can be confirmed that each magnetic substance observed from the SEM photograph was actually a cluster in which magnetic particles were aggregated. Each cluster has various shapes such as a long particle shape, and the average particle size was about 30 nm. The clusters were dispersed at an average interval of 3 nm (approximately in the range of 2.5 to 3.5 nm), expressed by the shortest distance between adjacent clusters. Each magnetic particle constituting the cluster had a particle size of about 8 to 10 nm (particularly, FIG. 14).

As described above, since the fine magnetic particles form clusters and the clusters are dispersed while maintaining an appropriate interval, it is considered that good electromagnetic conversion characteristics were obtained in the magnetic recording medium. . Therefore, the change in the structure of the magnetic layer was investigated by changing the Ar pressure when forming the magnetic layer. As a result, when the Ar pressure was 30 mTorr, the average interval between clusters was 1.5 nm, and the Ar pressure was 25 mT
When it was set to orr, the average interval between clusters was about 1 nm. On the other hand, when the Ar pressure was 75 mTorr, the average distance between clusters was 5 nm, and when the Ar pressure was 80 mTorr, the average distance between clusters was about 6 nm. Thus, the spacing between clusters increased as the Ar pressure increased. Considering the relationship between the Ar pressure and the electromagnetic conversion characteristics described above, the average interval between clusters is
It turns out that 1.5 nm-5 nm are preferable.

Next, as shown in FIG. 4, the magnetic layer has a laminated structure in which two magnetic thin films 11 and one non-magnetic thin film 12 (Cr layer) are laminated, and a single magnetic layer and a characteristic Were compared. Note that the saturation magnetization (Msδ) value of the magnetic layer having a laminated structure was about 1 memu / cm ² , as in the case of a single layer.
As a result, it was confirmed that the medium noise was lower than when a single magnetic layer was used, and the SN ratio was improved by about 1 to 2 dB.

Next, using a glass substrate having various surface roughnesses (Ra), magnetic disks were manufactured in the same manner as described above. Table 1 shows the results.

(Table 1) ――――――――――――――――――――――――――――― Substrate surface roughness (Ra) SN ratio Head adsorption ―― ――――――――――――――――――――――――――― 0.6nm + 1.2dB × 1.0nm + 0.5dB ○ 1.3nm + 0.3dB ○ 1. 6nm 0dB ○ 2.0nm -1.0dB ○ 2.4nm -1.6dB ○ ―――――――――――――――――――――――――――――

As shown in Table 1, in the case of a disk having a surface roughness (Ra) of 0.6 nm, it is necessary to take measures such as zone texture because the head is attracted. On the other hand, when a substrate having an Ra of 1.0 to 1.6 nm is used, practically no problem occurs if the magnetic layer is used, though the SN ratio is slightly reduced. However, Ra is 1.6n
When a substrate exceeding m is used, the SN ratio is remarkably reduced, and is not suitable for high-density recording. As described above, when a glass substrate having a surface roughness (Ra) of 1.0 to 1.6 nm is used, a recording medium suitable for high recording density can be obtained without performing zone texture.

[0041]

As described above, according to the present invention,
The magnetic layer formed on the nonmagnetic substrate and the underlayer is a layer containing clusters in which magnetic particles having a particle size of 5 nm to 20 nm are aggregated, and a nonmagnetic substance between the clusters. By setting the thickness to 0.5 nm to 5 nm, it is possible to provide a magnetic recording medium suitable for high-density recording with reduced noise and a high SN ratio.
In this magnetic recording medium, in the step of forming a magnetic layer on an underlayer formed on a nonmagnetic substrate,
In an atmosphere having a pressure in the range of orr to 75 mTorr,
A magnetic material and a nonmagnetic material that does not form a solid solution with the magnetic material can be efficiently formed by simultaneously sputtering.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a magnetic recording medium of the present invention.

FIG. 2 is a cross-sectional view schematically showing a structure of a magnetic layer in the magnetic recording medium shown in FIG.

FIG. 3 is a cross-sectional view schematically showing a structure of a magnetic layer formed on the magnetic recording medium shown in FIG. 1 at a lower gas pressure than that shown in FIG.

FIG. 4 is a cross-sectional view showing one embodiment of the magnetic recording medium of the present invention in which the magnetic layer has a laminated structure.

FIG. 5 is a diagram showing the relationship among Ar gas pressure, medium coercive force (Hc), and squareness ratio when a magnetic layer is formed by a sputtering method.

FIG. 6 is a diagram showing a relationship between Ar gas pressure and electromagnetic conversion characteristics (SN ratio) when forming a magnetic layer by a sputtering method.

FIG. 7 is a diagram illustrating a relationship between a substrate temperature and an electromagnetic conversion characteristic (SN ratio) when a magnetic layer is formed by a sputtering method.

FIG. 8 is a diagram showing the relationship between the amount of Si in the magnetic layer and the coercive force of the medium.

FIG. 9 is a diagram showing a relationship between the amount of Si in a magnetic layer and electromagnetic conversion characteristics (noise and SN ratio).

FIG. 10 is a photograph showing a result of observing an example of the magnetic layer of the present invention with a scanning electron microscope (SEM).

FIG. 11 is a photograph showing the result of observing a magnetic layer formed in the same manner as the magnetic layer shown in FIG. 10 by using a scanning electron microscope (SEM) except that no nonmagnetic material is spattered together.

FIG. 12 is a photograph showing a result of observing a magnetic layer formed in the same manner as the magnetic layer shown in FIG. 10 with a scanning electron microscope (SEM) except that the substrate was formed at a high temperature (300 ° C.). is there.

FIG. 13 is a photograph showing the result of observing an example of the magnetic layer of the present invention with a transmission electron microscope (TEM).

FIG. 14 is a photograph showing the result of observing an example of the magnetic layer of the present invention with a transmission electron microscope (TEM).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Underlayer 3 Magnetic layer 4 Protective layer 5 Lubricant 6 Cluster 7 Non-magnetic material 8 Void

 ──────────────────────────────────────────────────の Continuing on the front page (72) Keizo Miyata 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Taizo Hamada 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. A non-magnetic substrate, comprising: a base layer formed on the non-magnetic substrate; and a magnetic layer formed on the base layer, wherein the magnetic layer has a particle size of 5 nm to 20 nm. It includes clusters in which magnetic particles are aggregated, and a non-magnetic material existing between the clusters, and the average interval between the clusters is 1.
A magnetic recording medium having a thickness of 5 nm to 5 nm. 2. The non-magnetic material is at least one metal compound selected from silicon oxide, aluminum oxide, cobalt oxide, titanium oxide, chromium oxide, magnesium oxide, tantalum oxide, silicon nitride, aluminum nitride, titanium nitride and chromium nitride. The magnetic recording medium according to claim 1, comprising: 3. The magnetic layer, wherein the metal component contained in the metal compound constituting the nonmagnetic material is 5 to 1 with respect to the total amount of the metal component and the metal component constituting the magnetic particles.
3. The magnetic recording medium according to claim 1, wherein the content is 2.5 atomic%. 4. The non-magnetic substrate has a surface roughness of 1 nm to 1.
The magnetic recording medium according to any one of claims 1 to 3, which is in a range of 6 nm. 5. The magnetic recording medium according to claim 1, wherein the underlayer is a Cr layer or a Cr alloy layer. 6. The magnetic recording medium according to claim 1, wherein the thickness of the magnetic layer is 20 nm or less. 7. The magnetic recording medium according to claim 1, wherein the magnetic layer is a laminate of a magnetic thin film and a non-magnetic thin film. 8. A method comprising: forming a base layer on a non-magnetic substrate; and forming a magnetic layer on the base layer, forming the magnetic layer in an atmosphere having a pressure of 30 mtorr to 75 mtorr. And a method of manufacturing a magnetic recording medium, wherein the magnetic material and the non-magnetic material that does not form a solid solution are formed by simultaneous sputtering. 9. The method according to claim 8, wherein the magnetic layer is formed at a substrate temperature of 200 ° C. or lower. 10. The nonmagnetic substance is at least one metal compound selected from silicon oxide, aluminum oxide, cobalt oxide, titanium oxide, chromium oxide, magnesium oxide, tantalum oxide, silicon nitride, aluminum nitride, titanium nitride and chromium nitride. The method for manufacturing a magnetic recording medium according to claim 8, comprising: 11. The magnetic layer, wherein the metal component contained in the metal compound constituting the nonmagnetic material is 5 to 1 with respect to the total amount of the metal component and the metal component constituting the magnetic particles.
9. The method of claim 8, wherein the sputtering is performed at 2.5 atomic%.
11. The method for manufacturing a magnetic recording medium according to any one of items 10 to 10. 12. The nonmagnetic substrate has a surface roughness of 1 nm to
The method for manufacturing a magnetic recording medium according to any one of claims 8 to 11, wherein the magnetic recording medium has a range of 1.6 nm. 13. The method according to claim 8, wherein the underlayer is a Cr layer or a Cr alloy layer. 14. The method according to claim 8, wherein the thickness of the magnetic layer is 20 nm or less. 15. The method according to claim 8, wherein the magnetic layer is a laminate of a magnetic thin film and a non-magnetic thin film.