JP2002197635A - Magnetic recording medium, method of manufacturing for the same and magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which has excellent noise characteristics and heat resistant demagnetization characteristics, a method of manufacturing for the same and a magnetic recording and reproducing device. SOLUTION: In the magnetic recording medium provided with at least a nonmanagement substrate 1 and a soft magnetic ground surface film 2, alignment control film 3 and vertical magnetic film 4 formed on this nonmanagement substrate 1, the alignment control film 3 and the vertical magnetic film 4 in clude a layer consisting of >=1 layer of hcp structure of fcc structure, a soft magnetic film 5 consisting of a soft magnetic material is formed on the vertical magnetic film 4 and the soft magnetic film 5 and the vertical magnetic film 4 are exchange-bonded.

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 having a perpendicular magnetic film whose easy axis is mainly oriented perpendicular to a substrate, a method of manufacturing the same, and a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art Most magnetic recording media currently on the market are in-plane magnetic recording media in which the axis of easy magnetization in a magnetic film is mainly oriented horizontally to a substrate. To achieve high recording density in an in-plane magnetic recording medium, it is necessary to reduce the size of the magnetic particles and reduce noise, but when the particle size of the magnetic particles is reduced, the volume of the particles is reduced. Therefore, the deterioration of the reproduction characteristics due to the thermal fluctuation is likely to occur. Also, when the recording density is increased, medium noise may increase due to the influence of the demagnetizing field at the recording bit boundary. In contrast, the so-called perpendicular magnetic recording medium, in which the easy axis of magnetization in the magnetic film is mainly oriented perpendicular to the substrate, is less affected by the demagnetizing field at the bit boundary even when the recording density is increased,
Since a recording magnetic domain with a sharp boundary is formed, low noise can be achieved. Furthermore, perpendicular magnetic recording media have attracted much attention in recent years because they can increase the recording density even when the volume of magnetic particles is relatively large and can improve the resistance to thermal fluctuation. For example, Japanese Patent Application Laid-Open No. Sho 60-214417
Japanese Patent Application Laid-Open Publication No. H11-163,086 discloses a perpendicular magnetic recording medium using Ge and Si as a material of a base film of a perpendicular magnetic film made of a Co alloy. Also, JP-A-63-111117 discloses that
1 to 100 as a base film of a perpendicular magnetic film made of a Co alloy
A perpendicular magnetic recording medium in which a carbon-containing material film having a thickness of Å is formed is disclosed. However, these conventional magnetic recording media have a problem that it is difficult to increase the squareness ratio and the inverse magnetic domain nucleation magnetic field Hn is reduced. For this reason, there is a problem that the thermal fluctuation resistance at low recording density is inferior. On the other hand, as a magnetic recording medium capable of improving Hn, a magnetic recording medium provided with a multilayer film in which a transition metal (such as Co) and a noble metal (such as Pt) are stacked in multiple layers has been proposed. (JP-A-6-111403, JP-A-8-30951, US5660930)

[0003] Also, Japanese Patent No. 2615144 discloses that
On the perpendicular magnetic film, a layer made of a soft magnetic material is
It has been reported that the effect of reducing the distance between the magnetic head and the magnetic recording medium can be obtained by forming the magnetic head in the range of 0 nm. However, if a layer of a soft magnetic material having a thickness of 10 nm to 100 nm is provided, the leakage magnetic field from the perpendicular magnetic film as the recording layer passes through the inside of the layer of the soft magnetic material and is detected by the magnetic head. become. As a result, there is a problem that the leakage magnetic field detected by the magnetic head is greatly reduced, and the reproduction output is reduced.

[0004]

In recent years, there has been a demand for higher recording densities of magnetic recording media, and accordingly, there has been a demand for improved recording and reproducing characteristics. In order to improve the recording / reproducing characteristics, it is necessary to reduce the thickness of the magnetic film, which raises the problem of thermal demagnetization even for a perpendicular recording medium that is relatively advantageous for thermal demagnetization. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic recording medium having excellent recording / reproducing characteristics and excellent heat-resistant demagnetization characteristics, a method for manufacturing the same, and a magnetic recording / reproducing apparatus.

[0005]

In order to achieve the above object, the present invention employs the following constitution. The magnetic recording medium of the present invention is a magnetic recording medium comprising at least a non-magnetic substrate, a soft magnetic underlayer formed on the non-magnetic substrate, an orientation control film, and a perpendicular magnetic film. The magnetic film includes at least one layer having an hcp structure or an fcc structure, and a soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film. With such a structure, which is exchange-coupled, a high-output magnetic recording medium having excellent heat-resistant demagnetization characteristics and high output can be obtained.

Next, in the magnetic recording medium of the present invention, the product Bs of the saturation magnetic flux density Bs (T) of the soft magnetic film and the thickness t (nm) is obtained.
-T (T-nm) is 0.5 (T-nm) or more and 7.2.
(T · nm) It is preferable to be in the following range. next,
In the magnetic recording medium of the present invention, the saturation magnetic flux density Bs of the soft magnetic film
The product of (T) and the film thickness t (nm) Bs · t (T · nm)
Is preferably in the range of 0.5 (T · nm) or more and 3.6 (T · nm) or less. Next, in the magnetic recording medium of the present invention, the soft magnetic film preferably has a saturation magnetic flux density of 0.4 T or more. Next, in the magnetic recording medium of the present invention, the thickness of the soft magnetic film is preferably 0.5 nm or more and 5 nm or less. Next, the magnetic recording medium of the present invention is characterized in that the thickness of the soft magnetic film is 0.5 nm or more and 3 nm or less.

Next, in the magnetic recording medium of the present invention, the soft magnetic film contains 80 at% or more of Co, and Zr, Ta, Nb, Y
It is preferable to contain at least one element selected from the group consisting of 2 at% or more and have a saturation magnetic flux density Bs (T) of 0.8 (T) or more. Next, in the magnetic recording medium of the present invention, the soft magnetic film contains 60 at% or more of Fe,
at least one selected from r, Ta, Al, Si, and Hf
It is preferable to contain 2 at% or more of at least one kind of element and have a saturation magnetic flux density Bs (T) of 0.8 (T) or more. Next, in the magnetic recording medium of the present invention, the soft magnetic film has
at least at least one element selected from O, N, B, and C;
It is preferable to have a saturation magnetic flux density Bs (T) of (T) or more.

Next, in the magnetic recording medium of the present invention, the product Bs · t (T · nm) of the saturation magnetic flux density Bs (T) of the soft magnetic underlayer and the film thickness t (nm) is 40 (T · nm). nm) or more.

With the above-described structure, the characteristics of the soft magnetic film and the soft magnetic underlayer can be optimized, so that the magnetic recording medium has excellent recording / reproducing characteristics and more excellent heat-resistant demagnetizing characteristics. A recording medium is obtained.

Next, the magnetic recording medium of the present invention is characterized in that a part or the entire surface of the soft magnetic film on the side opposite to the perpendicular magnetic film is oxidized. With such a configuration, the recording and reproducing characteristics of the magnetic recording medium can be improved.

Next, the magnetic recording medium of the present invention is characterized in that a protective film is provided directly on the soft magnetic film, and the protective film is formed by a CVD method or an ion beam method. I do. Next, the magnetic recording medium of the present invention
The thickness of the protective film is 5 nm or less. With such a configuration, high-density recording and reproduction can be performed by thinning the protective film.

Next, according to the method of manufacturing a magnetic recording medium of the present invention, at least a soft magnetic underlayer, an orientation control film, and an axis of easy magnetization are oriented mainly perpendicular to the nonmagnetic substrate on the nonmagnetic substrate. A method for manufacturing a magnetic recording medium in which a perpendicular magnetic film and a perpendicular magnetic film are stacked by a film forming method, comprising a step of forming a soft magnetic film made of a soft magnetic material on the perpendicular magnetic film. With such a configuration, it is possible to manufacture a magnetic recording medium having excellent heat demagnetization characteristics.

Next, the method for manufacturing a magnetic recording medium according to the present invention is characterized in that it includes a step of forming a soft magnetic film and then oxidizing the surface of the soft magnetic film. With such a configuration, a magnetic recording medium having excellent recording / reproducing characteristics can be easily manufactured.

Next, a magnetic recording / reproducing apparatus according to the present invention comprises a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium comprises a non-magnetic substrate, An orientation control film for controlling the orientation of the perpendicular magnetic film between the substrate and the perpendicular magnetic film, wherein the easy axis comprises a perpendicular magnetic film mainly oriented perpendicular to the nonmagnetic substrate, and a reproduction waveform. A soft magnetic underlayer for controlling the shape is provided, and a soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film. With such a configuration, it is possible to obtain a magnetic recording / reproducing apparatus which can record and reproduce information at a high recording density and has excellent heat-resistant demagnetization characteristics.

Next, in the magnetic recording / reproducing apparatus according to the present invention, a protective film is provided immediately above the soft magnetic film, and the protective film is a CV.
It is characterized by being formed by the D method or the ion beam method. With such a configuration, it is possible to obtain a magnetic recording device capable of reducing the spacing between the magnetic head and the perpendicular magnetic film and capable of recording and reproducing higher density information.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing the configuration of a magnetic recording medium according to an embodiment of the present invention. As shown in FIG. 1, a magnetic recording medium according to the present embodiment has a soft magnetic under film 2, an orientation control film 3, a perpendicular magnetic film 4, a soft magnetic film 5, It is roughly composed of a film 6 and a lubricating film 7. Examples of the substrate 1 include an aluminum alloy substrate having a NiP plating film generally used as a substrate for a magnetic recording medium, a glass substrate (crystallized glass, tempered glass, etc.), a ceramic substrate, a carbon substrate, a silicon substrate, and silicon carbide. Substrates and the like can be mentioned. Alternatively, a substrate obtained by plating or sputtering a NiP film on such a substrate can be used. The average roughness Ra of the surface of the substrate 1 is 0.01 to 2 nm (more preferably, 0.1 to 2 nm).
05 to 1.5 nm). If it exceeds this range, the glide characteristics become insufficient. This is because if it is less than this range, head suction or head vibration tends to occur.

The soft magnetic underlayer 2 is provided for more firmly fixing the magnetization of the perpendicular magnetic film 4 for recording information in a direction perpendicular to the substrate 1. This effect is particularly remarkable when a single-pole head for perpendicular recording is used as a magnetic head for recording and reproduction. FIG. 2 shows a configuration diagram of a single-pole head having a general configuration. As shown in this figure, the single-pole head 10 is schematically composed of a magnetic pole 11 and a coil 12. The magnetic pole 11 has a substantially U-shape when viewed from the side. The thinner side is the main magnetic pole 13, and the other side is the auxiliary magnetic pole 14. The main pole 13 generates a magnetic field applied to the perpendicular magnetic film of the magnetic recording medium during recording, and detects magnetic flux from the perpendicular magnetic film during reproduction.

Using the single pole head 10 described above, the magnetic flux emitted from the tip of the main pole 13 during recording on the magnetic recording medium shown in FIG.
Magnetization in the direction perpendicular to Here, since the magnetic recording medium shown in FIG. 1 is provided with the soft magnetic underlayer 2, the magnetic flux from the main pole 13 of the single pole head 10
It is guided to the auxiliary magnetic pole 14 through the soft magnetic underlayer 2 to form a closed magnetic path. By forming such a closed magnetic path between the single-pole head 10 and the magnetic recording medium, the efficiency of magnetic flux in / out increases, and high-density recording / reproducing becomes possible.
Although the magnetic flux between the soft magnetic film 2 and the auxiliary magnetic pole 14 is opposite to the magnetic flux between the main magnetic pole 13 and the soft magnetic film 2, the area of the auxiliary magnetic pole 14 is larger than that of the main magnetic pole 13. Since it is wide enough, the magnetic flux density from the auxiliary pole 14 is sufficiently small,
The magnetic flux from the auxiliary magnetic pole 14 does not affect the magnetization of the perpendicular magnetic film 4.

As a material constituting the soft magnetic underlayer 2, an Fe alloy containing 60 at% or more of Fe can be used. Specifically, although not particularly limited, FeCo-based alloys (FeCo, FeCoV, etc.), FCo
eNi alloys (FeNi, FeNiMo, FeNiC)
r, FeNiSi, etc.), FeAl-based alloys (FeAl,
FeAlSi, FeAlSiCr, FeAlSiTiR
u), FeCr-based alloys (FeCr, FeCrTi,
FeCrCu), FeTa-based alloys (FeTa, Fa
TaC), FeC-based alloy, FeN-based alloy, FeSi
Alloys, FeP-based alloys, FeNb-based alloys, FeHf-based alloys, and the like. The soft magnetic underlayer 2
Are FeAlO, FeMgO, F
A fine crystal such as eTaN or FeZrN, or a film having a granular structure in which fine crystal grains are dispersed in a matrix can also be used. The soft magnetic underlayer 2 includes
In addition to the above, containing 80 at% or more of Co, Zr, Nb,
A Co alloy containing at least one of Ta, Cr, Mo and the like can be used. For example, CoZ
r, CoZrNb, CoZrTa, CoZrCr, Co
ZrMo and the like can be mentioned as preferable ones.
The soft magnetic underlayer 2 may be an alloy having an amorphous structure.

The soft magnetic underlayer 2 preferably has a saturation magnetic flux density of 0.8 T or more. This is because when the saturation magnetic flux density is smaller than 0.8T, the effect of controlling the reproduced waveform cannot be sufficiently obtained. The soft magnetic underlayer 2
Is preferably as small as possible, but practically it may be smaller than 200 (Oe) (15.8 × 10 ³ A / m). The thickness of the soft magnetic underlayer 2 is set to an optimum thickness depending on the saturation magnetic flux density of the material forming the soft magnetic underlayer 2. Specifically, the product of the saturation magnetic flux density Bs (T) of the material forming the soft magnetic underlayer and the thickness t (nm) of the soft magnetic underlayer 2 is Bs · t (T · nm) of 40.
(T · nm) or more (preferably 60 (T · nm) or more)
Is desirable. That is, Bs · t is 6
If 0 (T · nm), the saturation magnetic flux density is 1 (T)
When using the soft magnetic material described above, the thickness of the soft magnetic underlayer 2 may be set to 60 (nm).

The surface of the soft magnetic underlayer 2 (the orientation control layer 3
It is preferable that the material of the soft magnetic underlayer 2 is partially or completely oxidized. That is, the material (for example, FeCo) constituting the soft magnetic underlayer 2 is partially oxidized on the surface of the soft magnetic underlayer 2 (the surface on the orientation control film 3 side in FIG. 1) and in the vicinity thereof. Alternatively, it is preferable to form and arrange an oxide of the above material. With such a configuration, the magnetic fluctuation of the outermost surface of the soft magnetic underlayer 2 is suppressed, and the crystal grains of the orientation control film 3 formed on the soft magnetic underlayer 2 are refined to improve noise characteristics. The effect can be obtained. In addition, an oxide film is formed on the surface by being oxidized, and its function as a barrier layer works to suppress the migration of corrosive substances from the soft magnetic underlayer 2 or the nonmagnetic substrate 1 to the medium surface. Can be. As a result, the occurrence of corrosion on the medium surface can be suppressed.

The oxidized portion of the surface of the soft magnetic underlayer 2 is formed, for example, by forming the soft magnetic underlayer 2 and then exposing it to an atmosphere containing oxygen, or forming a portion close to the surface of the soft magnetic underlayer 2. It can be formed by a method in which oxygen is introduced into the process gas at the time of the formation. Specifically, the soft magnetic underlayer 2
Is exposed to oxygen alone or in a gas atmosphere in which oxygen is diluted with a rare gas such as argon.
What is necessary is just to hold | maintain about 2 to 30 seconds. Further, the surface of the soft magnetic underlayer 2 can be exposed to the atmosphere. The degree of oxidation can be adjusted by appropriately setting the amount of oxygen to be introduced and the exposure time to oxygen. For example, 10 ^-4 to 10 ^-6
By exposing the above surface for 0.1 to 30 seconds in an atmosphere of an oxygen gas pressure of 10 ⁻³ Pa or more with respect to a degree of vacuum of Pa, a predetermined oxidation state can be obtained. In particular, when a gas obtained by diluting oxygen with a rare gas such as argon is used, the degree of oxidation of the surface of the soft magnetic underlayer 2 is easily adjusted, so that stable production can be performed. When oxygen is introduced into the process gas for forming the soft magnetic underlayer 2, for example, if a sputtering method is used as the film formation method, the process gas into which oxygen is introduced is only used for a part of the film formation time. May be used to perform sputtering. As this process gas, for example, a gas in which oxygen is mixed with argon at a volume ratio of about 0.05% to 10% is preferably used. The thickness of the oxide film can be determined, for example, from a cross-sectional view using a transmission electron microscope (TEM). Alternatively, the oxidized state can be confirmed by Auger electron spectroscopy, SIMS, or the like.

A hard magnetic film made of a hard magnetic material having in-plane magnetic anisotropy can be provided between the soft magnetic underlayer 2 and the substrate 1. With such a configuration, generation of spike noise due to a huge magnetic domain formed by the soft magnetic underlayer 2 is prevented, and excellent error rate characteristics are achieved.
A magnetic recording medium capable of high-density recording can be obtained.
This is for the following reason. The soft magnetic underlayer 2 forms a huge magnetic domain in the in-plane direction of the substrate 1 because the coercive force is small and the direction of magnetization is easily changed. When a magnetic domain wall, which is a boundary between magnetic domains in the soft magnetic underlayer 2, is detected by a magnetic head, spike noise is generated, which causes a reduction in an error rate of a magnetic recording medium. Therefore, by providing the hard magnetic film between the soft magnetic underlayer 2 and the substrate 1, the hard magnetic film and the soft magnetic underlayer 2 are exchange-coupled, and the magnetization direction of the soft magnetic film 2 is forcibly set to the substrate. A large magnetic domain as described above can be prevented from being formed in one radial direction.
As the material used for the hard magnetic film, it is preferable to use a magnetic material made of an alloy of a transition metal and a rare earth element, and specifically, it is not particularly limited.
Examples thereof include a Cr alloy and a CoSm alloy. The hard magnetic film is magnetized in a radial direction from the center of the substrate in order to prevent the soft magnetic underlayer 2 from forming a domain wall in the radial direction of the substrate, and the hard magnetic film and the soft magnetic underlayer 2 are exchange-coupled. Is preferred.

The orientation control film 3 is provided for controlling the orientation and the grain size of the perpendicular magnetic film 4 described later.
Structure composed of structural material or hcp structural material, or B2
A structure in which a layer of a material having a structure or an amorphous structure and a layer of a material of an fcc structure or an hcp structure can be stacked. Specifically, although not particularly limited, B2
NiAl, FeAl, CoFe, Co
Examples include Zr, NiTi, and AlCo.
In addition, Ti, Zr, Y, Z
n, Ru, Re, Hf, etc. are applicable.
c, Ni, Pd, Pt, Al, Cu, A
g and the like. Alternatively, for the above materials,
The other elements (Cr, Mo, S
i, Mn, W, Nb, Ti, Zr, B, C, N, or one or more elements selected from the group consisting of O) may be added. In addition, as an amorphous structure,
Examples thereof include C, Si, Co, and alloys thereof.

The magnetic recording medium of the present invention has a soft magnetic underlayer 2
By providing the orientation control film 3 between the perpendicular magnetic film 4 and the perpendicular magnetic film 4, the crystal grains constituting the perpendicular magnetic film 4 can be refined;
The vertical orientation is improved. As a result, the magnetic recording medium of the present invention has excellent noise characteristics and characteristics suitable for high-output, high-density recording. The thickness of the orientation control film 3 is preferably 50 nm or less (more preferably, 30 nm or less). If the film thickness exceeds the above range, the distance between the magnetic head and the soft magnetic underlayer 2 at the time of recording / reproducing becomes large, so that the resolution of the reproduced signal is lowered and the noise characteristic is deteriorated. Also,
When the film thickness is reduced, the material is not particularly limited as long as the above-mentioned material can maintain its structure.
It is preferably at least nm.

It is preferable to use a Co alloy for the perpendicular magnetic film 4. For example, a CoCrPt alloy, a CoPt alloy, or Ta, Zr, Nb, Cu,
Re, Ru, V, Ni, Mn, Ge, Si, B, O, N
An alloy to which at least one or two or more elements selected from the above are added can be used. Further, the perpendicular magnetic film 4 can have a laminated structure of Pt or Pd and Co alone or a Co alloy. As the Co alloy, the above-mentioned CoCrPt-based alloy or CoPt-based alloy can be used. In particular, in a CoCrPt-based alloy,
In order to increase the perpendicular magnetic anisotropy, the Pt content is set to 8 to 24a.
It is more preferable to be t%. Although the above-described Co alloy and the perpendicular magnetic film having a laminated structure all constitute a polycrystalline film, the magnetic recording medium of the present invention can employ a perpendicular magnetic film having an amorphous structure. Specifically, although not particularly limited, an alloy containing a rare earth element such as a TbFeCo-based alloy can be used.

The perpendicular magnetic film 4 is made of the above transition metal (Co, C).
In the case of forming a multilayer structure of an o-alloy) and a noble metal element (Pt, Pd, or the like), the layer made of the noble metal element preferably has a thickness of 0.4 nm or more and 1.4 nm or less. This is because the coercive force (H
This is because c) and the magnetic field for generating a reversed domain nucleus (Hn) decrease, and it becomes difficult to control the layer thickness. When the thickness exceeds 1.4 nm, noise characteristics deteriorate. On the other hand, the thickness of the layer made of the transition metal is the same as that of the layer made of the noble metal element, and the thickness is preferably in the range of 0.1 nm to 0.6 nm, more preferably 0.1 nm.
m and 0.4 nm or less. Either of the transition metal layer and the noble metal layer may be used as the uppermost layer in the perpendicular magnetic film 4, but it is preferable to arrange a noble metal layer at the lowermost layer. The thickness of the perpendicular magnetic film 4 may be appropriately optimized depending on the intended reproduction output. However, in both cases where the above-described Co alloy is used and when a magnetic film having a multilayer structure is used, if the thickness is too large, noise may be generated. Practically, there are problems such as deterioration of characteristics and reduction of resolution.
It is preferably about 100 nm.

A non-magnetic intermediate film made of a non-magnetic element can be provided between the orientation control film 3 and the perpendicular magnetic film 4. With such a configuration, the coercive force can be improved by improving the orientation of the perpendicular magnetic film 4.
The non-magnetic intermediate film is not particularly limited, but may be a non-magnetic CoCr alloy or a CoCr alloy formed of Ta, Z
r, Nb, Cu, Re, Ru, Ni, Mn, Ge, S
An alloy to which one or more elements selected from i, O, N, and B are added can be used. Alternatively, Co
And Ta, Zr, Nb, Cu, Re, Ru, Ni, Mn,
A non-magnetic alloy obtained by alloying one or more elements selected from Ge, Si, O, N, and B can also be used. If the thickness of the non-magnetic intermediate film is too large, the distance between the perpendicular magnetic film 4 and the soft magnetic underlayer 2 becomes large, so that the resolution decreases and the noise characteristics deteriorate.
It is preferably at most 20 nm, more preferably at most 10 nm.

The soft magnetic film 5 is a film made of a soft magnetic material formed on the perpendicular magnetic film 4. The soft magnetic film 5 is made of a material containing 80 at% or more of Co,
It is preferable to use a Co alloy containing 2 at% or more of at least one element among Zr, Ta, Nb, and Y and having a saturation magnetic flux density Bs (T) of 0.8 (T) or more. Examples of such a Co alloy include CoZr,
CoZrNb, CoZrTa, CoZrCr, CoNb
Preferred examples include a Y-based alloy.
Further, as a material of the soft magnetic film 5, Fe is contained at 60 at% or more, and at least one element of Ta, Zr, Al, Si, and Hf is contained at 2 at% or more.
It is preferable to use an Fe alloy having a saturation magnetic flux density Bs (T) of (T) or more. Examples of such Fe alloys include FeAlSi, FeTaC, and FeAlSiTiR.
u, FeHfO, FeTaN, and FeZrO-based alloys. Alternatively, as a material of the soft magnetic film 5, Fe is contained at 60 at% or more, and O, N, B,
It is preferable to use an Fe alloy containing at least one element of C in an amount of 2 at% or more and having a saturation magnetic flux density Bs (T) of 0.8 (T) or more. Such Fe alloys include FeN, FeTaC, FeHfO, FeT
Suitable materials include fine crystals such as aN, FeAlO, FeB, and FeZrN alloys, or materials having a granular structure in which fine crystal grains are dispersed in a matrix. Further, the soft magnetic film 5 can be made of an alloy having an amorphous structure.

The soft magnetic film 5 preferably has a saturation magnetic flux density of 0.4 T or more. This is because when the saturation magnetic flux density is smaller than 0.4 T, an excessively large film thickness is required to suppress the fluctuation of the magnetic flux on the surface of the perpendicular magnetic film 4 and exchange coupling with the perpendicular magnetic film 4 is insufficient. This is because there is a possibility of becoming. It is preferable that the coercive force of the soft magnetic film 5 be as small as possible.
It may be smaller than 0 (Oe) (15.8 × 10 ³ A / m). The thickness of the soft magnetic film 5 is set to an optimum thickness according to the saturation magnetic flux density of the material forming the soft magnetic film 5. Specifically, the saturation magnetic flux density Bs of the material forming the soft magnetic film
Bs which is the product of (T) and the thickness t (nm) of the soft magnetic film 5
-T (T-nm) is 0.5 (T-nm) or more and 7.2.
(T.nm) or less.
It is more preferably 5 (T · nm) or more and 3.6 (T · nm). That is, Bs · t is set to 2.4 (T · n
m), and when a soft magnetic material having a saturation magnetic flux density of 1.2 (T) is used, the thickness of the soft magnetic underlayer 2 may be 2 (nm). Further, since the soft magnetic film 5 is formed immediately below the protective film 6, its surface roughness (Ra) affects the flying height of the head. Therefore, the surface roughness (Ra) is preferably smaller than 2 nm from the flying height of the head required for high-density recording.

The surface of the soft magnetic film 5 (the surface on the side of the protective film 6 in the figure) may be configured such that a part or the entire surface is oxidized. That is, the material of the soft magnetic film 5 disposed on or near the surface of the soft magnetic film 5 may be partially oxidized or form an oxide of the above material. With such a configuration, the fluctuation of the magnetization of the soft magnetic film 5 at the interface between the soft magnetic film 5 and the protective film 6 can be reduced, so that the noise characteristics can be improved. The oxidation of the surface of the soft magnetic film 5 can be performed by the same method as that of the soft magnetic underlayer 2. That is, the soft magnetic film 5 can be formed by exposing the surface of the soft magnetic film 5 to oxygen or an atmosphere containing oxygen, or by forming the soft magnetic film 5 with a process gas obtained by adding oxygen to a rare gas.

The protective film 6 is for preventing corrosion of the perpendicular magnetic film 4, preventing damage to the medium surface when the head comes in contact with the medium, and ensuring lubrication characteristics between the head and the medium. Conventionally known materials can be used. For example, a single composition of C, SiO ₂ , or ZrO ₂ or a material containing these as a main component and containing other elements can be used.
It is desirable that the thickness of the protective film 4 be in the range of 1 nm to 10 nm. In addition, a known lubricant such as perfluoropolyether, fluorinated alcohol, or fluorinated carboxylic acid can be used for the lubricating film 7. It is preferable that the type and the film thickness are appropriately adjusted to an optimum thickness according to the characteristics of the protective film and the lubricant used.

A feature of the magnetic recording medium of the present invention is that the soft magnetic film 5 is provided between the perpendicular magnetic film 4 and the protective film 6 as described above. The provision of the soft magnetic film 5 can improve the heat-resistant demagnetization characteristics and the reproduction output. This is considered for the following reason. First, when recording is performed on the magnetic recording medium shown in FIG. 1, the perpendicular magnetic film 4 is magnetized in the direction perpendicular to the substrate 1, so that a magnetic field in the direction perpendicular to the substrate 1 is formed inside the perpendicular magnetic film 4. You. Then, the magnetic flux leaking above the perpendicular magnetic film 4 (on the side of the protective film 6) is detected by the head and becomes a reproduction output. However, along with the leakage flux, a fluctuation of the magnetic flux exists on the surface of the perpendicular magnetic film 4, and this fluctuation is sensed by the head and causes noise, and the fluctuation causes the magnetization of the perpendicular magnetic film 4 to become unstable. It is presumed that it becomes. Perpendicular magnetic film 4 like the magnetic recording medium of the present invention.
When a soft magnetic film 5 made of a soft magnetic material is provided between the magnetic film and the protective film 6 and the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled, The inside of the soft magnetic film 5 is magnetized in a direction substantially horizontal to the substrate 1 by the leakage magnetic flux, and a closed magnetic path is formed together with the magnetization of the vertical magnetic film 4. Therefore, the fluctuation of the magnetic flux on the surface of the perpendicular magnetic film 4 is taken into the closed magnetic path, and the magnetic flux on the surface of the perpendicular magnetic film 4 is stabilized. Thereby, the original reproduction output of the perpendicular magnetic film 4 which is not affected by the fluctuation can be obtained, and the influence of the fluctuation on the magnetization of the perpendicular magnetic film 4 can be prevented, so that the heat-resistant demagnetization of the magnetic recording medium is improved. I do. Further, in the magnetic recording medium of the present invention, since the soft magnetic underlayer 2 is provided between the perpendicular magnetic film 4 and the substrate 1 as shown in FIG. The magnetization forms a closed magnetic path in the magnetic recording medium via the soft magnetic film 5 and the soft magnetic underlayer 2. As a result, the magnetization of the perpendicular magnetic film 4 is more firmly fixed, so that a magnetic recording medium having excellent heat demagnetization characteristics can be obtained.

Although the soft magnetic film 5 has the above-mentioned effects, the soft magnetic film 5 having an excessively large thickness shields the magnetic flux leaking from the perpendicular magnetic film 4, and as a result, the reproduction output is lowered and the reproduction is further reduced. This causes a decrease in heat-resistant demagnetization due to a decrease in output. Therefore, it is necessary to appropriately set the thickness and the magnetic flux shielding property of the soft magnetic film 5. Specifically, as described above, the saturation magnetic flux density Bs (T) of the soft magnetic film 5 and
The product Bs · t (T · n) of the thickness t (nm) of the soft magnetic film 5
m) is preferably in the range of 0.5 to 10 (T · nm), more preferably 0.5 to 5 (T · nm). Further, by setting the product of the saturation magnetic flux density of the soft magnetic film 5 and the thickness thereof in a predetermined range, the shielding property of the magnetic flux by the soft magnetic film 5 can be controlled to be constant regardless of the material. Becomes possible.

Next, the exchange coupling between the perpendicular magnetic film 4 and the soft magnetic film 5 will be described in detail with reference to MH (magnetization) curves shown in FIGS. In the following description, in order to separate the magnetization of the soft magnetic underlayer 2 which is not directly related to the exchange coupling, the measurement result of the magnetization curve of the magnetic recording medium manufactured without the soft magnetic underlayer 2 is described. Shall be used. FIG. 3A shows the orientation control film 3 and the soft magnetic film 5 among the layers constituting the magnetic recording medium shown in FIG.
And a magnetic recording medium formed by depositing only the protective film 6,
It is an MH curve measured by applying a magnetic field in the direction perpendicular to the substrate, wherein the horizontal axis indicates the intensity of the applied magnetic field and the vertical axis indicates the magnetization.
Then, Hm _aa in FIG. 3 (a) shows a saturation magnetic field. FIG.
(B) is an MH curve measured by applying a magnetic field in the in-plane direction of the substrate to the magnetic recording medium. The horizontal axis represents the intensity of the applied magnetic field, and the vertical axis represents the magnetization. In FIG. 3B, Hm _ab indicates a saturation magnetic field, and Hc _ab indicates a coercive force. Since the orientation control film 3 and the protective film 6 of the magnetic recording medium produced above have no magnetization, FIG.
(B) shows the MH curve of the soft magnetic film 5.

FIG. 4A shows the orientation control film 3 and the perpendicular magnetic film 4 among the layers constituting the magnetic recording medium shown in FIG.
And MH curves measured by applying a magnetic field in the direction perpendicular to the substrate to the magnetic recording medium on which only the protective film 6 is formed. The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. And
In FIG. 4A, Hm _ba indicates a saturation magnetic field, and Hc _ba indicates a coercive force. FIG. 4B is an MH curve measured by applying a magnetic field in the in-plane direction to the magnetic recording medium. The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. And
In FIG. 4B, Hm _bb indicates a saturation magnetic field, and Hc _bb indicates a coercive force. As shown in FIGS. 4A and 4B, the perpendicular magnetic film 4 has a large coercive force and magnetization in the direction perpendicular to the substrate, and the coercive force and magnetization in the in-plane direction of the substrate are smaller than those in the perpendicular direction. And extremely small.

FIG. 5A shows the orientation control film 3 and the perpendicular magnetic film 4 among the layers constituting the magnetic recording medium shown in FIG.
And a magnetic recording medium in which only the soft magnetic film 5 and the protective film 6 are formed and the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled to each other. -H
The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. Then, Hm _ca in FIG. 5 (a) saturation field, H
c _ca indicates a coercive force, and Hn _ca indicates a magnetization reversal magnetic field. FIG. 5B is an MH curve measured by applying a magnetic field in the in-plane direction to the magnetic recording medium. The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. Then, Hm _cb in FIG. 5 (b) saturation field, Hc _cb represents the coercive force.

FIG. 6A shows the orientation control film 3 and the perpendicular magnetic film 4 among the layers constituting the magnetic recording medium shown in FIG.
And only the protective film 6 is formed, and the perpendicular magnetic film 4 and the soft magnetic film 5 are formed.
Is an MH curve measured by applying a magnetic field in a direction perpendicular to the substrate to a magnetic recording medium configured to prevent exchange coupling.
The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. In FIG. 6A, Hm _da indicates a saturation magnetic field, and Hc _da indicates a coercive force. FIG. 6B is an MH curve measured by applying a magnetic field in the in-plane direction to the magnetic recording medium,
The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. Then, Hm _db in FIG. 3 (b) saturation field, Hc _db represents the coercive force.

FIG. 7A shows the orientation control film 3 and the perpendicular magnetic film 4 among the layers constituting the magnetic recording medium shown in FIG.
A magnetic field in the direction perpendicular to the substrate is applied to a magnetic recording medium in which only the protective film 6 is formed and the ratio Mr / Ms of the saturation magnetization (Ms) to the residual magnetization (Mr) of the perpendicular magnetic film 4 is smaller than 1. Is applied, and the horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. And FIG.
Hm _ea is the saturation magnetic field in (a), Hc _ea coercive force, Hn _ea
Indicates a magnetization reversal magnetic field. FIG. 7B shows an M-measurement obtained by applying a magnetic field in the in-plane direction to the magnetic recording medium.
The horizontal axis indicates the intensity of the applied magnetic field, and the vertical axis indicates the magnetization. Then, Hm _eb in FIG. 7 (b) saturation field,
Hc _eb indicates the coercive force.

First, a magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled will be described with reference to FIG. When a magnetic field is applied in the direction perpendicular to the substrate of the magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled, the magnetic recording medium follows the initial magnetization curve (not shown) and is magnetized in the positive direction. When the applied field reaches a saturation magnetic field Hm _ca, magnetization of the magnetic recording medium takes a constant value is saturated (Ms). This Ms
Is larger than Ms of only the perpendicular magnetic film 4 shown in FIG. Conversely, when the applied magnetic field is decreased from this state, the magnetic recording medium maintains the saturation magnetization Ms even at the point of the magnetic field 0 as shown in FIG. 5A, and the slope of the MH curve at the point of the magnetic field 0 is reduced. Is almost zero. Further reversing the direction of the applied magnetic field and increasing the magnetic field in the negative direction,
When the magnetic field reaches the magnetization reversal magnetic field (Hn _ca ), the magnetization of the magnetic recording medium starts to decrease rapidly (magnetization reversal starts). As described above, in the magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled, the magnetic field intensity at which the direction of the magnetization starts to reverse from positive to negative is one point (Hn _ca ).

Next, a magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are not exchange-coupled will be described with reference to FIG. When a magnetic field in the direction perpendicular to the substrate is applied to a magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are not exchange-coupled,
It is magnetized in the positive direction following an initial magnetization curve not shown. When the applied field reaches a saturation magnetic field Hm _da, the magnetization of the magnetic recording medium takes a constant value is saturated (Ms). Conversely, when the applied magnetic field is reduced from this state, the saturation magnetic field Hm _aa of the soft magnetic film 5 (the same value as the saturation magnetic field Hm _aa of the soft magnetic film 5 shown in FIG. 3) is obtained as shown in FIG. When the magnetization reversal of the soft magnetic film starts and the magnetic field is zero, the magnetization of the magnetic recording medium becomes smaller than the above Ms. This indicates that the magnetization of the magnetic recording medium is changed even by a small external magnetic field, and it is expected that the magnetic recording medium is inferior in heat resistance demagnetization characteristics. Further, by inverting the direction of the applied magnetic field, increasing the magnetic field in the negative direction, where the applied magnetic field reaches the magnetization reversal field Hn _da, inversion of the perpendicular magnetic film begins. As described above, in the magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are not exchange-coupled, the magnetic field at which the magnetization reversal of the soft magnetic film 5 starts and the magnetic field at which the magnetization reversal of the perpendicular magnetic film 4 starts (Hm _aa and Hn _da ), magnetization reversal occurs. In such a magnetic recording medium, the perpendicular magnetic film 4 and the soft magnetic film 5
In addition to reducing the stabilizing effect of the perpendicular magnetic film 4 due to the formation of the closed magnetic circuit, the magnetization of the perpendicular magnetic film 4 may become unstable by providing the soft magnetic film 5. .

Also, from the measurement results of the magnetic recording medium shown in FIG. 7 where the ratio Mr / Ms of the saturation magnetization (Ms) to the residual magnetization (Mr) of the perpendicular magnetic film 4 is smaller than 1, the perpendicular magnetic film 4
The same can be said for a magnetic recording medium in which the soft magnetic film 5 and the soft magnetic film 5 are not exchange-coupled. That is, MH at the point of zero magnetic field
Since the slope of the curve is not zero, the magnetization of the magnetic recording medium changes even with a small magnetic field, indicating that the magnetic recording medium is unstable with respect to an external magnetic field.

As described above, the magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled has an M-
The slope of the H curve is almost 0, and this slope does not change due to the provision of the soft magnetic film 5. Therefore, in such a magnetic recording medium, the magnetization of the soft magnetic film 5 and the perpendicular magnetic film 4 forms a closed magnetic path, and the effect of stabilizing the magnetization of the perpendicular magnetic film 4 is great. The characteristics can be improved. On the other hand, in a magnetic recording medium in which the perpendicular magnetic film 4 and the soft magnetic film 5 are not exchange-coupled, the magnetization reversal of the soft magnetic film 5 occurs near the magnetic field 0, so that the magnetic field 0
, The slope of the MH curve becomes extremely large, and the stability of the magnetization of the perpendicular magnetic film 4 to the magnetic field deteriorates. As a result, it is considered that the heat-resistant demagnetization characteristics also deteriorate. That is, in a magnetic recording medium in which the soft magnetic film 5 is provided on the perpendicular magnetic film 4, it is essential that the perpendicular magnetic film 4 and the soft magnetic film 5 are exchange-coupled. If this requirement is not satisfied, There is a possibility that the magnetization stability of the perpendicular magnetic film 4 is lower than when the soft magnetic film 5 is not provided.

In addition, the soft magnetic film 5 may be a carbon film formed by a CVD method or an ion beam method.
It has a special effect when it is applied to. That is, when the above-mentioned CVD carbon film or ion beam carbon film is used as the protective film 6, it is superior in hardness to a normal carbon thin film. Spacing can be reduced. However, on the other hand, these thin films are so-called DLC (diamond-like carbon) films, and since they are insulators, their surfaces are extremely easily charged. Then, the magnetic field due to the electric charges accumulated on the surface may make the magnetization of the perpendicular magnetic film 4 unstable.
Therefore, since the magnetic recording medium of the present invention includes the soft magnetic film 5, the soft magnetic film 5 shields the magnetic field due to the charge on the surface of the protective film 6, and plays a role of protecting the magnetization of the perpendicular magnetic film 4. . As a result, the magnetic recording medium of the present invention does not deteriorate the heat-resistant demagnetization characteristics even when using an extremely thin CVD carbon film or ion beam carbon film as the protective film.
The soft magnetic film 5 according to the present invention is particularly effective when the thickness of the protective film 6 is extremely thin, that is, 5 nm or less, and the perpendicular magnetic film 4 is easily affected by charges on the surface of the protective film 6.

In order to manufacture the magnetic recording medium having the above structure, a soft magnetic underlayer 2 is formed on a substrate 1 shown in FIG. 1 by a sputtering method or the like.
Is subjected to an oxidation treatment, and then an orientation control film 3, a perpendicular magnetic film 4, a soft magnetic film 5, and a protective film 6 are sequentially formed by a sputtering method or the like. Next, the lubricating film 7 is formed by a dip coating method, a spin coating method, or the like. In the method for manufacturing a magnetic recording medium, the substrate 1
A step of forming a hard magnetic film between the substrate and the soft magnetic underlayer 2,
A step of forming a non-magnetic intermediate film between the orientation control film 3 and the perpendicular magnetic film 4 and a step of oxidizing the surface of the soft magnetic film 5 can also be included.

In the above-described method of manufacturing a magnetic recording medium, when a magnetic film having a multilayer structure of Co or a Co alloy and Pt or Pd or an alloy thereof is used as the perpendicular magnetic film 4, the material of the Co or Co alloy is used. The perpendicular magnetic film 4 is formed by alternately using the first target composed of and the second target composed of Pt and / or Pd, and alternately sputtering the material of each target.

In the case where the surface of the soft magnetic underlayer 2 or the soft magnetic film 5 is subjected to an oxidation treatment, the surface is maintained for a predetermined time in an atmosphere of oxygen or a mixed gas of oxygen and argon. The degree of oxidation of the surfaces of the soft magnetic underlayer 2 and the soft magnetic film 5 and the amount of oxygen attached to these surfaces are adjusted. Alternatively, after the soft magnetic underlayer 2 and the soft magnetic film 5 are formed,
By sputtering using a target gas equivalent to a target used for these film formation and a gas in which oxygen is mixed with a rare gas (such as argon) as a process gas, the soft magnetic under film 2 and the soft magnetic film 5 are formed. Then, a layer containing oxygen may be formed. Alternatively, oxygen may be mixed into the process gas only for a specific time during the formation of the soft magnetic underlayer 2 and the soft magnetic film 5. Specifically, for example, when the soft magnetic underlayer 2 is formed by sputtering with argon, the sputtering is performed by mixing oxygen into argon only for a part of the film formation time (for example, one second before the completion of the film formation). Just do it.

As a method for forming the protective film 6, sputtering using a carbon target, a method for forming a carbon film using a CVD method or an ion beam method can be used. Further, R using a target of SiO ₂ or ZrO ₂
A method of forming a thin film of SiO ₂ or ZrO ₂ by F sputtering or reactive sputtering using a gas containing oxygen as a process gas while using a target of Si or Zr can be applied. In the present invention, it is preferable to use a CVD method or an ion beam method as the protective film 6.
If these film forming methods are used, the protective film 6 having an extremely large hardness and excellent characteristics can be formed, and the film thickness can be made much smaller than the conventional carbon film. In addition, high-density recording and reproduction can be performed by reducing the spacing between the perpendicular magnetic film 4 and the magnetic head used for recording and reproducing information.

FIG. 8 is a sectional view showing an example of a magnetic recording / reproducing apparatus according to the present invention. The magnetic recording / reproducing apparatus shown in this figure includes a magnetic recording medium 20 having the same configuration as the magnetic recording medium shown in FIG. 1, a medium driving unit 21 for rotating this magnetic recording medium 20, and a magnetic recording medium 20. Magnetic head 22 for recording and reproducing information, and head drive unit 23
And a recording / reproducing signal processing system 24. The recording / reproducing signal system 24 can process input data and send a recording signal to the magnetic head 22, or can process a reproducing signal from the magnetic head 22 and output data.

Further, in the magnetic recording / reproducing apparatus of the present invention, it is preferable that the protective film included in the magnetic recording medium 20 is composed of a CVD carbon film or an ion beam carbon film. With such a configuration, the spacing between the magnetic head and the magnetic film of the magnetic recording medium is reduced to enable high-density recording and reproduction, and the soft magnetic film is provided on the magnetic recording medium as described above. Therefore, it has excellent heat demagnetization characteristics.

In particular, if a single-pole head is used as the magnetic head in the above-described magnetic recording device, a closed magnetic path is formed between the single-pole head and the magnetic recording medium, so that the magnetic flux to the magnetic recording medium is reduced. The entry / exit efficiency is remarkably improved, and the magnetization can be firmly fixed at the time of recording on the perpendicular magnetic film, so that higher density recording / reproducing is possible.

[0052]

EXAMPLES The effects of the present invention will be clarified using examples. However, the present invention is not limited to the following examples. <Example 1> First, a cleaned glass substrate (manufactured by OHARA, 2.5 inch in outer diameter) was housed in a film forming chamber of a DC magnetron sputtering apparatus (C-3010, manufactured by Anelva), and the ultimate vacuum degree was 1 After evacuation of the inside of the film formation chamber until the pressure became × 10 ⁻⁵ Pa, 89Co-4 was placed on the glass substrate.
A soft magnetic underlayer was formed using a Zr-7Nb target at a substrate temperature of 100 ° C. or lower. Then, the substrate is
Heated to 00 ° C., and a 50 Ni-
An alignment control film having a laminated structure of 8 nm using a 50Al target and 20 nm using a Ru target was formed, and then a perpendicular magnetic film of 30 nm was formed using a 62Co-20Cr-14Pt-4B target. Next, 89C
A 2 nm soft magnetic film was formed using an o-4Zr-7Nb target. Saturation magnetic flux density Bs (T) of this soft magnetic film
Bs · t (T · nm), which is the product of the thickness of the soft magnetic film and the thickness t (nm)
Is 2.4 (T · nm). In the sputtering step, the film was formed at a pressure of 0.5 Pa using argon as a process gas for film formation. Then, CVD
A protective film made of a 5 nm DLC film was formed by the method.
Next, a 2 nm thick lubricating film made of perfluoropolyether was formed on the protective film 6 by dip coating. Through the above steps, the magnetic recording medium of Example 1 was obtained.
In this magnetic recording medium, the fact that the perpendicular magnetic film and the soft magnetic film are exchange-coupled is determined by using a vibration-type magnetic characteristic measuring device (VS).
M).

<Comparative Examples 1 and 2> Next, as Comparative Example 1,
A magnetic recording medium was manufactured in the same manner as in Example 1 except that the soft magnetic film on the perpendicular magnetic film was not provided. Next, as Comparative Example 2, a magnetic recording medium was manufactured in the same manner as in Example 1 except that the perpendicular magnetic film and the soft magnetic film formed thereon were not exchange-coupled.

The recording / reproducing characteristics and the thermal demagnetization characteristics of the magnetic recording media of Example 1 and Comparative Examples 1 and 2 were evaluated. The evaluation of the recording / reproducing characteristics was performed using a read / write analyzer RWA-1632 manufactured by GUZIK and a spin stand S1701MP. As a recording / reproducing head, a composite thin-film magnetic recording head having a giant magnetoresistive (GMR) element in a reproducing section was used. The linear recording density for measurement was 50 kFCI for reproduction and the error rate was 600 kFCI. In addition, the evaluation of the thermal demagnetization characteristics was performed after heating the substrate to 70 ° C. and writing at a linear recording density of 50 kFCI.
Output decrease rate (% / de) with respect to output 1 second after writing
) was calculated based on (S ₀ −S) × 100 / (S ₀ × 3). Incidentally, S ₀ represents the reproduction output of one second time elapses after the signal recorded on the magnetic recording medium, S is shows a reproduction output after 1000 seconds.

Table 1 shows the measurement results. As shown in Table 1, the magnetic recording medium of Example 1 satisfying the requirements of the present invention is the magnetic recording medium of Comparative Example 1 in which the soft magnetic film is not formed, and the soft magnetic film and the perpendicular magnetic film are exchange-coupled. Compared with the magnetic recording medium of Comparative Example 2 which does not have the above, the reproducing output, the error rate, and the thermal demagnetization characteristics are more excellent. In particular, the magnetic recording medium of Comparative Example 2 in which the soft magnetic film and the perpendicular magnetic film were not exchange-coupled had a lower error rate than the magnetic recording medium of Comparative Example 1 in which the soft magnetic film was not provided.

[0056]

[Table 1]

<Examples 2 to 8> Next, as Examples 2 to 8, magnetic recording media were manufactured in the same manner as in Example 1 except that the composition and thickness of the orientation control film were as shown in Table 2. . As a result of measuring VSM for these magnetic recording media,
In all the magnetic recording media, it was confirmed that the perpendicular magnetic film and the soft magnetic film were exchange-coupled. The recording / reproducing characteristics and the thermal demagnetization characteristics of the magnetic recording media of Examples 2 to 8 were evaluated in the same manner as in Example 1. Table 2 shows the results.
Table 2 also shows the measurement results of the magnetic recording medium of Example 1. As shown in Table 2, the magnetic recording media of Examples 2 to 8 satisfying the requirements of the present invention have the same reproduction output, error rate, and heat-resistant demagnetization characteristics even when the composition of the orientation control film is variously changed. It was confirmed that excellent characteristics were exhibited.

[0058]

[Table 2]

<Embodiments 9-12> Next, Embodiments 9-12
As shown in Table 3, the saturation magnetic flux density Bs (T) of the soft magnetic film and the product Bs · t (T · nm) of the thickness t (nm) are in the range of 1 to 10 (T · nm) as shown in Table 3. The magnetic recording medium was manufactured by changing it. The configuration and manufacturing process of the soft magnetic film other than Bs · t were the same as in Example 1. VSM measurement of these magnetic recording media confirmed that the perpendicular magnetic film and the soft magnetic film were exchange-coupled in each of the magnetic recording media.

The magnetic recording media of Examples 9 to 12 were evaluated for recording / reproducing characteristics and heat-resistant demagnetization characteristics in the same manner as in Example 1. Table 3 shows the results. Table 3 also shows the measurement results of the magnetic recording medium of Example 1. From the measurement results shown in Table 3, the Bs · t (T · nm) of the soft magnetic film
However, the magnetic recording media of Examples 1 and 9 to 11 having a range of 0.5 nm or more and 7.2 nm or less are superior to the magnetic recording media of Comparative Example 1 in reproduction output and heat-resistant demagnetization characteristics. It was confirmed that. In particular, Bs · t of the soft magnetic film
It was confirmed that the magnetic recording media of Examples 1 and 9 having (T · nm) in the range of 0.5 nm or more and 3.6 nm or less had a good error rate in addition to the above. On the other hand, the magnetic recording medium of Example 12 in which the Bs · t (T · nm) of the soft magnetic film did not satisfy the requirements of the present invention was Comparative Example 1 shown in Table 1.
Reproduction output and heat demagnetization characteristics were inferior to those of the magnetic recording medium of No. It is considered that this is because the leakage magnetic flux of the perpendicular magnetic film detected by the magnetic head was decreased due to the soft magnetic film thickness being too thick, and the medium noise caused by the soft magnetic film was increased.

[0061]

[Table 3]

<Examples 13 to 16> Next, the product Bs of the saturation magnetic flux density Bs (T) of the soft magnetic film and the film thickness t (nm) was obtained.
T (T / nm) is fixed at 2.4 nm, and the saturation magnetic flux densities Bs (T) of the soft magnetic film are 0.3 T and 0.4, respectively.
A magnetic recording medium of an example was manufactured in the same manner as in Example 1 except that the films were formed to have T, 1.2T, 2.0T, and 2.4T.

The recording / reproducing characteristics and the thermal demagnetization characteristics of the magnetic recording media of Examples 13 to 16 were evaluated in the same manner as in Example 1. Table 4 shows the results. Table 4 also shows the measurement results of the magnetic recording medium of Example 1. As shown in Table 4, Examples 1 and 1 satisfying the requirements of the present invention
Each of the magnetic recording media Nos. 4 to 16 was excellent in error rate and thermal demagnetization characteristics. On the other hand, the magnetic recording medium of Example 13 in which the saturation magnetic flux density of the soft magnetic film is small and does not satisfy the requirements of the present invention has a weak effect of suppressing the fluctuation of the magnetization of the surface of the perpendicular magnetic film, and thus has a poor thermal demagnetization characteristic. It was inferior.

[0064]

[Table 4]

<Embodiment 17> Next, in order to clarify the effect of oxidizing the surface of the soft magnetic film, an embodiment 17 was described.
A soft magnetic film is formed to a thickness of 2 nm using an 89Co-4Zr-7Nb target, and then the surface of the soft magnetic film is oxidized while being kept in an argon-oxygen mixed gas atmosphere with an oxygen partial pressure of 0.05 Pa. DL by CVD method
A magnetic recording medium was manufactured by forming a C film to a thickness of 5 nm. The configuration and manufacturing steps other than those described above are the same as those in the first embodiment.

Table 5 shows the results of evaluating the recording / reproducing characteristics of this magnetic recording medium in the same manner as in Example 1. Table 5 also shows the evaluation results of the magnetic recording medium of Example 1 in which the surface of the soft magnetic film was not oxidized for comparison. As shown in Table 5, the magnetic recording medium of Example 17 in which the surface of the soft magnetic film was oxidized had the same thermal demagnetization characteristics as those of Example 1, and the error rate was higher than that of the magnetic recording medium of Example 1. Was also excellent. This can be said to be an effect that the fluctuation of the magnetization near the surface of the soft magnetic film is suppressed by the oxidation treatment, and the medium noise is reduced.

[0067]

[Table 5]

[0068]

As described in detail above, the magnetic recording medium of the present invention comprises at least a nonmagnetic substrate, a soft magnetic underlayer formed on the nonmagnetic substrate, an orientation control film, and a perpendicular magnetic film. Wherein the alignment control film and the perpendicular magnetic film have at least one hcp structure or fcc structure.
A soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film, and the soft magnetic film and the perpendicular magnetic film are exchange-coupled. Fluctuations in the magnetization of the surface of the perpendicular magnetic film can be suppressed, and the magnetization of the perpendicular magnetic film can be stabilized. Therefore, according to the present invention, it is possible to provide a magnetic recording medium having excellent heat demagnetization characteristics.

In the above magnetic recording medium, the product Bs · t (T · nm) of the saturation magnetic flux density Bs (T) of the soft magnetic film and the film thickness t (nm) is 0.5 or more and 7.2. (Tn
m) or less, preferably 0.5 to 3.6 (Tn)
m) Within the following range, the read output from the perpendicular magnetic film can be increased and the heat-resistant demagnetization characteristics can be improved. In the above magnetic recording medium, if the saturation magnetic flux density of the soft magnetic film is 0.4 T or more, it is possible to obtain the effect of improving the heat-resistant demagnetization characteristics of the soft magnetic film without deteriorating the noise characteristics. it can. Further, in the above magnetic recording medium, if the thickness of the soft magnetic film is 0.5 nm or more and 5 nm or less, preferably 0.5 nm or more and 3 nm or less, a magnetic recording medium excellent in both reproduction output and heat-resistant demagnetization characteristics is provided. Can be provided.

Next, in the above-mentioned magnetic recording medium, if a part or the whole of the surface of the soft magnetic film on the opposite side to the perpendicular magnetic film is oxidized, the above-mentioned cause of medium noise can be obtained. Since fluctuations in magnetization on the surface of the soft magnetic film can be suppressed, a magnetic recording medium having excellent noise characteristics can be provided.

Next, in the above magnetic recording medium, a protective film is provided directly on the soft magnetic film. If the protective film is formed by the CVD method or the ion beam method, the protective The soft magnetic film prevents the perpendicular magnetic film from destabilizing the magnetization due to the electric charge staying on the surface of this kind of protective film while reducing the film thickness so that high-density recording and reproduction of information can be performed. Therefore, a magnetic recording medium having excellent heat resistance and demagnetization can be obtained.

Next, according to the method of manufacturing a magnetic recording medium of the present invention, at least a soft magnetic underlayer, an orientation control film, and an easy axis of magnetization are oriented on a nonmagnetic substrate mainly perpendicular to the nonmagnetic substrate. A method for manufacturing a magnetic recording medium, comprising laminating a perpendicular magnetic film by a film forming method, comprising a step of forming a soft magnetic film made of a soft magnetic material on the perpendicular magnetic film. A magnetic recording medium having excellent characteristics can be easily manufactured.

Next, if the method for manufacturing a magnetic recording medium described above includes a step of oxidizing the surface of the soft magnetic film after forming the soft magnetic film, the vicinity of the surface of the soft magnetic film can be improved. Thus, it is possible to easily manufacture a magnetic recording medium having excellent noise characteristics by suppressing the fluctuation of magnetization in the magnetic recording medium.

Next, a magnetic recording / reproducing apparatus according to the present invention includes a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium. An orientation control film for controlling the orientation of the perpendicular magnetic film between the substrate and the perpendicular magnetic film, wherein the easy axis comprises a perpendicular magnetic film mainly oriented perpendicular to the nonmagnetic substrate, and a reproduction waveform. A soft magnetic under film for controlling the shape is provided, and a soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film. And high-density recording / reproduction is possible. Further, if a protective film is provided directly on the soft magnetic film and the protective film is formed by a CVD method or an ion beam method, the spacing between the perpendicular magnetic film and the magnetic head can be reduced. So you can
It is possible to record and reproduce information at a higher recording density.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross-sectional structure of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic side view of a general single-pole head.

FIG. 3A shows an orientation control film, a soft magnetic film,
M in the direction perpendicular to the substrate of the magnetic recording medium on which only the protective film is formed
FIG. 3 (b) shows the MH curve in the in-plane direction of the substrate.
It is a curve.

FIG. 4A is an MH curve of a magnetic recording medium in which only an orientation control film, a perpendicular magnetic film, and a protective film are formed in a direction perpendicular to the substrate, and FIG. M in in-plane direction
-It is an H curve.

5A is an MH curve of a magnetic recording medium in which a perpendicular magnetic film and a soft magnetic film are exchange-coupled in a direction perpendicular to the substrate, and FIG. 5 is an MH curve of FIG.

FIG. 6A is an MH curve of a magnetic recording medium in which a perpendicular magnetic film and a soft magnetic film are not exchange-coupled in a direction perpendicular to the substrate, and FIG. 5 is an MH curve of FIG.

FIG. 7A is an MH curve of a magnetic recording medium in which the ratio of saturation magnetization (Ms) and residual magnetization (Mr) Mr / Ms is smaller than 1 in the direction perpendicular to the substrate, and FIG. b) is an MH curve in the in-plane direction of the substrate.

FIG. 8 is a schematic sectional view showing an example of a configuration of a magnetic recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

1 ... (non-magnetic) substrate, 2 ... soft magnetic underlayer, 3 ...
..Alignment control films, 4 ... perpendicular magnetic films, 5 ... soft magnetic films

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat 参考 (Reference) G11B 5/851 G11B 5/851 (72) Inventor Yang Teru 5-1, Yawata Kaigandori, Showa, Ichihara-shi, Chiba Inside Denko H.D. (72) Inventor Akira Sakawaki 5-1, Yawata Kaigan-dori, Ichihara-shi, Chiba F-term in Showa Denko H.D. Co., Ltd. AA07 BC01 GA17

Claims (17)

[Claims] 1. A magnetic recording medium comprising at least a non-magnetic substrate, a soft magnetic underlayer formed on the non-magnetic substrate, an orientation control film, and a perpendicular magnetic film, wherein the orientation control film and the perpendicular magnetic film are A soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film, wherein the soft magnetic film and the perpendicular magnetic film are exchange-coupled. A magnetic recording medium, comprising: 2. The saturation magnetic flux density Bs (T) of the soft magnetic film,
The product Bs · t (T · nm) of the film thickness t (nm) is 0.5
2. The magnetic recording medium according to claim 1, wherein the range is not less than (T.nm) and not more than 7.2 (T.nm). 3. The saturation magnetic flux density Bs (T) of the soft magnetic film,
The product Bs · t (T · nm) of the film thickness t (nm) is 0.5
3. The magnetic recording medium according to claim 2, wherein the range is not less than (T.nm) and not more than 3.6 (T.nm). 4. The saturation magnetic flux density Bs (T) of the soft magnetic film is:
The magnetic recording medium according to any one of claims 1 to 3, wherein the magnetic recording medium is 0.4 (T) or more. 5. The soft magnetic film has a thickness of 0.5 nm or more and 5 n or more.
The magnetic recording medium according to any one of claims 1 to 4, wherein m is equal to or less than m. 6. The soft magnetic film has a thickness of 0.5 nm or more and 3 n or more.
The magnetic recording medium according to claim 5, wherein m is equal to or less than m. 7. The soft magnetic film contains 80 at% or more of Co, 2 at% or more of at least one element selected from Zr, Ta, Nb, and Y, and has a saturation of 0.8 (T) or more. 7. The magnetic recording medium according to claim 1, having a magnetic flux density Bs (T). 8. The soft magnetic film contains at least 60 at% of Fe and at least 2 at% of at least one element selected from Zr, Ta, Al, Si, and Hf.
The magnetic recording medium according to any one of claims 1 to 6, wherein the magnetic recording medium has a saturation magnetic flux density Bs (T) of (T) or more. 9. The soft magnetic film contains at least 60 at% of Fe, at least 2 at% of at least one element selected from O, N, B, and C, and has a saturation of at least 0.8 (T). 7. The magnetic recording medium according to claim 1, having a magnetic flux density Bs (T). 10. A saturation magnetic flux density Bs of a soft magnetic underlayer.
The product of (T) and the film thickness t (nm) Bs · t (T · nm)
The magnetic recording medium according to any one of claims 1 to 9, wherein is equal to or more than 40 (T · nm). 11. The magnetic recording medium according to claim 1, wherein a part or the whole of the surface of the soft magnetic film opposite to the perpendicular magnetic film is oxidized. 12. The method according to claim 1, wherein a protective film is provided directly on the soft magnetic film, and the protective film is formed by a CVD method or an ion beam method.
12. The magnetic recording medium according to any one of items 11 to 11. 13. The magnetic recording medium according to claim 12, wherein the thickness of the protective film is 5 nm or less. 14. On a non-magnetic substrate, at least a soft magnetic underlayer, an orientation control film, and a perpendicular magnetic film whose easy axis of magnetization is oriented mainly perpendicular to the non-magnetic substrate are formed by lamination. A method for manufacturing a magnetic recording medium, comprising: forming a soft magnetic film made of a soft magnetic material on the perpendicular magnetic film. 15. The method according to claim 1, further comprising, after forming the soft magnetic film, oxidizing a surface of the soft magnetic film.
5. The method for manufacturing a magnetic recording medium according to item 4. 16. A magnetic recording medium comprising: a magnetic recording medium; and a magnetic head for recording and reproducing information on and from the magnetic recording medium. A perpendicular magnetic film oriented vertically, an orientation control film between the substrate and the perpendicular magnetic film for controlling the orientation of the perpendicular magnetic film, and a soft magnetic under film for controlling the shape of the reproduced waveform Wherein a soft magnetic film made of a soft magnetic material is formed on the perpendicular magnetic film. 17. The magnetic device according to claim 16, wherein a protective film is provided directly on the soft magnetic film, and the protective film is formed by a CVD method or an ion beam method. Recording and playback device.