JP2003132515A - Magnetic recording medium, method for manufacturing the same, and magnetic recording/reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium in which the thermal instability is improved and the decrease in the output is prevented, in which the magnetic coupling between magnetic layers provided on up and down sides of a nonmagnetic coupling layer is stronger, and which has a higher coercive force and a lower noise. SOLUTION: In the magnetic recording medium consisting of at least a nonmagnetic substrate, a nonmagnetic under layer, the magnetic layers, and a protective film, it is solved by the magnetic recording medium having at least one nonmagnetic coupling layer on the nonmagnetic under layer and having the structure in which the magnetic layers are provided on up and down sides of the nonmagnetic coupling layer, in which the first magnetic layer from the side of the nonmagnetic substrate is one selected from a CoRu based alloy, a CoRe based alloy, a CoIr based alloy, and a CoOs based alloy.

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 hard disk device and the like, a method for manufacturing the magnetic recording medium and a magnetic recording / reproducing apparatus, and more particularly to a magnetic recording medium having excellent recording / reproducing characteristics. .

[0002]

2. Description of the Related Art A hard disk drive (HDD), which is one type of magnetic recording / reproducing apparatus, currently has an annual recording density of 60.
%, And that trend is said to continue.
A magnetic recording head suitable for high recording density and a magnetic recording medium are being developed. The magnetic recording medium used therein is required to have a high recording density, and accordingly, improvement of coercive force and reduction of medium noise are required.

As a magnetic recording medium used in a hard disk device, a structure in which a metal film is laminated on a substrate for a magnetic recording medium by a sputtering method is mainly used. Aluminum substrates and glass substrates are widely used as substrates for magnetic recording media. The aluminum substrate is a mirror-polished Al—Mg alloy substrate on which a NiP film is formed by electroless plating to a thickness of about 10 μm and the surface of which is further mirror-finished. There are two types of glass substrates, amorphous glass and crystallized glass. Both glass substrates are mirror-finished.

In a magnetic recording medium for a hard disk device which is generally used at present, a nonmagnetic underlayer (NiAl, Cr, Cr alloy, etc.) and a nonmagnetic intermediate layer (CoCr, CoCrTa alloy, etc.) are formed on a nonmagnetic substrate. , Magnetic layer (CoC
rPtTa, CoCrPtB alloy, etc.) and a protective film (carbon, etc.) are sequentially formed, and a lubricating film made of a liquid lubricant is formed thereon.

In order to improve recording density, SNR (Signal to Noise R) when recording at high frequency is performed.
There is a need to improve the audio. Kenneth
E. J. , "Magnetic materials"
and structures for thin-f
ilm recording media ”, JOUR
NAL OF APPLIED PHYSICS Vo
187, No. 9, 5365 (2000), it is argued that in order to improve the SNR, it is necessary to make the diameter of the crystal grains of the recording layer small and uniform.

On the other hand, reducing the diameter of the crystal grains in the recording layer is accompanied by reducing the volume, so that the magnetization state becomes thermally unstable.
et al. , "Temperature Depe
Ndence of Thermal Stabili
ty in Longitudinal Medi
a ", IEEE Trans. Magn. Vol 35,
No. 5,2736 (1999). In order to improve the SNR of the magnetic recording medium, it is necessary to reduce the diameter of the crystal grains in the recording layer, but this reduces the volume of the crystal grains and causes thermal instability of magnetization.

Japanese Unexamined Patent Publication No. 2001-56921 proposes one solution to this problem by using antiferromagnetic coupling in the recording layer. By utilizing the fact that the magnetizations of the upper and lower magnetic layers are reversed by forming the magnetic layers as recording layers above and below the non-magnetic coupling layer such as ruthenium. Since the magnetization directions are reversed in the vertical direction, the portion magnetically involved in the recording / reproducing becomes substantially thinner than the thickness of the entire recording layer. Therefore, the SNR can be improved. On the other hand, since the volume of crystal grains in the entire recording layer is large, it is possible to improve thermal instability of magnetization. A medium using this technique is an AFC medium (Anti-ferromagnetically-Co).
upmedia) or SFM (Synth)
(etic Ferrimagnetic Media)
Is commonly called. In this specification, the term "AFC medium" is used.

[0008]

The structure of a conventional AFC medium is shown in FIGS. The AFC medium in FIG. 5 has a structure in which one nonmagnetic coupling layer is sandwiched between two magnetic films. The AFC medium of FIG. 6 has a structure in which another non-magnetic coupling layer and a magnetic layer are further laminated on the magnetic layer of FIG. The layers in each figure are 501: non-magnetic substrate, 502:
Non-magnetic underlayer, 503: non-magnetic intermediate layer, 504: first magnetic layer, 505: non-magnetic coupling layer, 506: second magnetic layer, 5
07: protective film, 508: lubricating layer, 601: non-magnetic substrate,
602: non-magnetic underlayer, 603: non-magnetic intermediate layer, 60
4: first magnetic layer, 605: non-magnetic coupling layer, 606: second
Magnetic layer, 607: non-magnetic coupling layer, 608: third magnetic layer,
609: a protective film and 610: a lubricating layer.

The magnetization of the first magnetic layer is M1, the volume of the crystal grains is V1, the magnetization of the second magnetic layer is M2, the volume of the crystal grains is V1.
2, the total volume of the magnetic layer is (V1 + V2)
And increase the thermal stability. However, since the magnetization of the magnetic layer as a whole becomes (M2-M1), the magnetization of the magnetic layer as a whole is lowered and the output of the recording layer is lowered.

Akira Kakeihi, "Prom
ising SFM (Synthetic Ferri)
magnetic Media) Technology
y ", technical conference, S
session 2a, DISKCON USA 2001
As reported in, in the AFC medium shown in FIG. 5, when the thickness of the first magnetic layer is set to 5 nm, thermal demagnetization (Signal Decay) indicating thermal instability of the magnetic layer is exhibited.
Is -0.1 (dB / decade) to -0.025
(DB / decade), but the magnetization of the magnetic layer is 0.37 (memu / cm ² ) to 0.30 (mem)
u / cm ² ). The thermal demagnetization is a value indicating a decrease in the output over time, and it can be said that the smaller the absolute value of this value, the more thermally stable. Specifically, when the output (dB) is plotted on the ordinate and the time is plotted on the abscissa with the common logarithm, the slope is the thermal demagnetization (dB / decade). As described above, the conventional AFC medium method has a problem that an attempt to improve thermal instability causes a decrease in output.

On the contrary, in the conventional AFC medium, in order to improve thermal instability, it is necessary to increase the thickness of the first magnetic layer. If the thickness of the first magnetic layer is increased, there is a problem that the magnetic coupling between the magnetic layers provided above and below the non-magnetic coupling layer becomes weak.

The present invention has been made in view of the above circumstances, and improves thermal instability and suppresses a decrease in output,
An object of the present invention is to provide a magnetic recording medium having stronger magnetic coupling between magnetic layers provided above and below a non-magnetic coupling layer, having higher coercive force and lower noise, and a manufacturing method thereof. .

[0013]

In order to solve the above problems, the present invention uses a CoRu-based alloy, a CoRe-based alloy, a CoIr-based alloy, and a CoOs-based alloy for the first magnetic layer, so that even a thin film thickness can be obtained. The inventors have found that it is possible to obtain an AFC medium capable of exhibiting a high coercive force and a high squareness ratio and improving the thermal stability without causing a reduction in the reproduction signal output, and completed the present invention. (1) A first invention for solving the above-mentioned problems, in a magnetic recording medium comprising at least a non-magnetic substrate, a non-magnetic underlayer, a magnetic layer and a protective film, at least one non-magnetic coupling layer on the non-magnetic under-layer. Having a structure in which the magnetic layer is provided above and below the non-magnetic coupling layer, and the first magnetic layer from the non-magnetic substrate side is made of CoRu-based alloy, CoRe-based alloy, CoIr-based alloy, CoOs-based alloy. It is a magnetic recording medium characterized in that it is any one selected. (2) In the second invention for solving the above-mentioned problems, the lattice constant of the alloy of the first magnetic layer is a = 0.25 nm to 0.
26 nm, c = 0.407 nm to 0.422 nm is the magnetic recording medium described in (1). (3) The third invention for solving the above-mentioned problems is characterized in that the alloy of the first magnetic layer has a transition temperature from the hcp structure to the fcc structure of 600 ° C. or higher (1) or (2) ) Is a magnetic recording medium. (4) A fourth invention for solving the above-mentioned problem is that, when the alloy of the first magnetic layer is a CoRu-based alloy, the Ru content is 5 to 30 at%, and when the alloy is a CoRe-based alloy, the Re content is Re. Is 5 to 30 at%, the content of Ir is 8 to 30 at% in the case of CoIr-based alloy, and the content of Os is 5 to 30 at% in the case of CoOs-based alloy (1) to (3). (4) The magnetic recording medium according to any one of (1) to (4). (5) The fifth invention for solving the above-mentioned problems is characterized in that the film thickness of the first magnetic layer is 0.5 to 3 nm, (1) to (4) Magnetic recording medium. (6) In the sixth invention for solving the above-mentioned problems, the nonmagnetic coupling layer is made of Ru, Rh, Ir, Cr, Re, Ru-based alloy, Rh.
It is any one selected from a group alloy, an Ir alloy, a Cr alloy, and a Re alloy, and has a film thickness of 0.5 to 1.5.
The magnetic recording medium according to any one of (1) to (5), which has a thickness of nm. (7) According to a seventh invention for solving the above-mentioned problems, magnetic characteristics have anisotropy in a circumferential direction with respect to a non-magnetic substrate, and the non-magnetic underlayer is made of Cr, or Cr and Ti, Mo. , Al, T
(1) to (6), which has a multilayer structure including a layer made of any one of Cr alloys composed of one or more selected from a, W, Ni, B, Si and V. The magnetic recording medium according to any one of items. (8) An eighth invention for solving the above-mentioned problems, wherein the magnetic property is in-plane isotropic with respect to the non-magnetic substrate, and the non-magnetic underlayer is a NiAl-based alloy, a RuAl-based alloy, or Cr
And Cr consisting of one or more selected from Ti, Mo, Al, Ta, W, Ni, B, Si and V
The magnetic recording medium according to any one of (1) to (6), which has a multilayer structure including a layer made of any one of alloys. (9) A ninth invention for solving the above-mentioned problems is characterized in that the non-magnetic substrate is any one selected from a glass substrate and a silicon substrate. (1) to (8) It is the magnetic recording medium described. (10) The tenth invention for solving the above-mentioned problems is characterized in that the non-magnetic substrate is one in which a surface of any one selected from an Al substrate, a glass substrate and a silicon substrate is plated with NiP (1 ) To (8) is the magnetic recording medium according to any one of items. (11) According to an eleventh invention for solving the above-mentioned problems, the second magnetic layer or the third magnetic layer is a CoCrPt-based alloy, a CoCrPtTa-based alloy, a CoCrPtB-based alloy,
The CoCrPtBY alloy (Y is at least one selected from Ta and Cu) selected from the group consisting of any one of (1) to (10). It is a magnetic recording medium. (12) A twelfth invention for solving the above-mentioned problems provides a magnetic recording medium including a step of forming a nonmagnetic underlayer on a nonmagnetic substrate, a step of forming a magnetic layer, and a step of forming a protective film. In the manufacturing method, at least 1 is formed on the non-magnetic underlayer.
And a CoRu-based alloy, a CoRe-based alloy, a CoIr-based alloy,
First of any one selected from CoOs alloys
A method of manufacturing a magnetic recording medium, comprising: a step of forming a second magnetic layer; and a step of forming a second magnetic layer after forming a nonmagnetic coupling layer. (13) A thirteenth invention for solving the above-mentioned problems is a magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is (1). A magnetic recording / reproducing apparatus, which is the magnetic recording medium as described in any one of (1) to (11).

[0014]

FIG. 1 shows an embodiment of a magnetic recording medium of the present invention. The magnetic recording medium shown here is
On the non-magnetic substrate 101, the non-magnetic underlayer 102, the first magnetic layer 103, the non-magnetic coupling layer 104, the second magnetic layer 105,
The protective film 106 and the lubricating layer 107 are sequentially laminated.

FIG. 2 shows another embodiment of the magnetic recording medium of the present invention. The magnetic recording medium shown here has a magnetic layer of FIG. 1 and another non-magnetic coupling layer. It has a structure in which magnetic layers are laminated. On the non-magnetic substrate 101, a non-magnetic underlayer 102, a first magnetic layer 103, a non-magnetic coupling layer 104, a second magnetic layer 105, a non-magnetic coupling layer 104,
The third magnetic layer 202, the protective film 106, and the lubricating layer 107 are sequentially laminated.

As the non-magnetic substrate in the present invention, an Al alloy having a NiP plated film, which is generally used as a substrate for a magnetic recording medium, (hereinafter, referred to as NiP plated Al) is used.
Call it the substrate. ), As a non-magnetic substrate, glass,
Examples thereof include those made of non-metal materials such as ceramics, silicon, silicon carbide, carbon, and resins, and those having a film of NiP or NiP alloy formed on a substrate made of these non-metal materials.

As the recording density is increased, the head is required to have a lower flying height, so that a high smoothness of the substrate surface is required. That is, the non-magnetic layer substrate used in the present invention has an average surface roughness Ra of 2 nm (20 Å) or less, preferably 1 nm or less.

As the non-metal material, it is preferable to use a glass substrate in terms of cost and durability. From the viewpoint of surface smoothness, it is preferable to use a glass substrate, a silicon substrate or the like.

As the glass substrate, crystallized glass or amorphous glass can be used. General-purpose soda lime glass and aluminosilicate can be used as the amorphous glass. As the crystallized glass, lithium-based crystallized glass can be used. From the viewpoint of being adaptable to a wider variety of usage environments, crystallized glass having excellent chemical durability is preferable. Here, the constituents of the crystallized glass containing SiO ₂ and Li ₂ O are the points of matching the thermal expansion coefficient with other parts when actually used by incorporating them into the drive device, or It is preferable in terms of rigidity during assembly and use.

Examples of the ceramic substrate include a general-purpose sintered body containing aluminum oxide, silicon nitride or the like as a main component, and fiber reinforced products thereof.

A nonmagnetic underlayer is formed on the nonmagnetic substrate. When the magnetic property has anisotropy in the circumferential direction with respect to the non-magnetic substrate, the non-magnetic underlayer is made of Cr and T.
The layer can be a layer composed of a Cr alloy composed of one or more selected from i, Mo, Al, Ta, W, Ni, B, Si and V. The film thickness is 1 to 4
It is preferably 0 nm. When the magnetic property is in-plane isotropic with respect to the non-magnetic substrate, the non-magnetic underlayer is a layer having a B2 structure at room temperature, such as a NiAl-based alloy or a RuAl-based alloy, or Cr and Ti, Mo, A
1 selected from 1, Ta, W, Ni, B, Si and V
It is possible to form a layer composed of one kind or two or more kinds of Cr alloys. The film thickness is preferably 1 to 40 nm. If the film thickness is less than 1 nm, crystal growth is insufficient. This is because if the film thickness exceeds 40 nm, the crystal grains may become too large and the medium noise may be deteriorated.

The non-magnetic underlayer preferably has a multi-layer structure in which the above-mentioned layers are laminated in any combination. The total film thickness is preferably 5 to 150 nm. This is because the multi-layered structure ensures uniform crystal orientation and good electromagnetic conversion characteristics. For example, when the magnetic characteristics have anisotropy in the circumferential direction with respect to the non-magnetic substrate, the non-magnetic underlayer is made of Cr, Ti, and M on the layer made of Cr.
It is preferable to stack a layer made of a Cr alloy composed of one or more selected from o, Al, Ta, W, Ni, B, Si and V. For example, when the magnetic property is in-plane isotropic with respect to the non-magnetic substrate,
The nonmagnetic underlayer is formed by depositing Cr, Ti, and M on a layer having a B2 structure at room temperature, such as a NiAl alloy or a RuAl alloy.
It is preferable to stack a layer made of a Cr alloy composed of one or more selected from o, Al, Ta, W, Ni, B, Si and V.

The magnetic recording medium of the present invention has at least one nonmagnetic coupling layer on the nonmagnetic underlayer. The non-magnetic coupling layer has a structure in which magnetic layers are provided on the upper side and the lower side. For example, the lower magnetic layer is the first from the non-magnetic substrate side.
In the case of the th magnetic layer, the first magnetic layer is used, and the magnetic layer on the upper side is the second magnetic layer.

The non-magnetic coupling layer is made of Ru, Rh, Ir, C.
r, Re, Ru-based alloy, Rh-based alloy, Ir-based alloy, Cr
It is made of any one selected from the group alloys and Re alloys. These substances have a binding energy coefficient (Exchange Energy
When used as a non-magnetic coupling layer, it is possible to increase the degree of reversal of the magnetization of the magnetic layers provided above and below that layer. The binding energy coefficient is a value representing the strength of exchange interaction between the magnetic layers provided above and below, and the larger the value, the better. In particular, since Ru has the largest binding energy coefficient among the above substances, it is desirable to use Ru for the nonmagnetic coupling layer.

The thickness of the non-magnetic coupling layer is 0.2-1.
5 nm (more preferably 0.6 to 1.0 nm)
Is preferred. This is because those within this range can obtain sufficient antiferromagnetic coupling. Ru-based alloys include RuCo, RuCr, RuNb, RuTa, RuW
Is mentioned. Rh-based alloys include RhCo and RhC
r and RhTa are mentioned. As an Ir-based alloy, Tr
Examples include Co, IrCr, and IrTa. Examples of the Cr-based alloy include CrCo. As Re alloy,
Examples include ReCo, ReCr, and ReTa.

The first magnetic layer is made of CoRu alloy, Co
Since it is selected from Re-based alloy, CoIr-based alloy, and CoOs-based alloy, the first magnetic layer can be directly provided on the non-magnetic underlayer without providing the non-magnetic intermediate layer, which is preferable.

In the conventional magnetic recording medium, a nonmagnetic intermediate layer is used under the magnetic layer to promote the epitaxial growth of the magnetic film. For the non-magnetic underlayer, a substance having an fcc structure similar to that of Cr or a Cr alloy, or a substance having no Bcp structure such as NiAl or RuAl, which does not have an hcp structure, is used. However, when a magnetic film is formed directly on the non-hcp structure film, the initial growth is not successful and the orientation at the initial stage of film formation becomes poor. For this reason, it has been attempted to form a material having an hcp structure such as CoCr as a non-magnetic intermediate layer to improve the orientation of the magnetic layer from the time of initial growth.

In the present invention, based on the finding that CoRu alloys, CoRe alloys, CoIr alloys, and CoOs alloys can be formed on the non-hcp structure while maintaining good orientation from the time of initial growth. Either of them is used as the first magnetic layer.

Conventionally used layers made of materials such as CoCrPtB alloy, CoCrPtTa alloy, and CoCrPtBCu alloy are made of Cr, Pt, B, Cu to form grain boundaries in order to improve the separation state of magnetic particles.
Are added. The magnetic particles have an hcp structure,
The grain boundary part due to addition of Cr, Pt, B, Cu, etc. is non-h
Because of the cp structure, the growth of the hcp structure of the magnetic particles is hindered. On the other hand, the CoRu alloy of the first magnetic layer of the present invention,
CoRe alloy, CoIr alloy, and CoOs alloy have an hcp structure. When the content is within the preferable range, Co is completely contained in Co, so that a more pure hcp structure is obtained, which is preferable. Therefore, even on the non-hcp structure, it is possible to grow in a state where good orientation is maintained from the time of initial growth.
In particular, when the first magnetic layer is a CoRe alloy, the ratio of the a-axis to the c-axis of the hcp structure of Re is 1.61.
Since the ratio of the a-axis to the c-axis of the p structure is close to 1.62, considering that the second magnetic layer is a Co alloy, it is preferable from the viewpoint of epitaxial growth of each magnetic layer.

The alloy crystal of the first magnetic layer has an hcp structure, and its lattice constant is a = 0.250 nm.
0.260 nm (more preferably 0.252 to 0.25
7 nm. ), C = 0.407 nm to 0.422 nm (more preferably 0.410 to 0.419 nm). Co has an hcp structure and its lattice constants are a = 0.251 nm and c = 0.407 nm, but the second magnetic layer which is the second magnetic layer from the nonmagnetic substrate side or the nonmagnetic substrate side. To the third magnetic layer, which is the third
The Co alloy used in the magnetic layer has an increased coercive force and SNR.
Since Pt is added for the purpose of improving Pt, their lattice constants are widened. A preferable addition amount of Pt is 8 to
The lattice constant of Co alloy at 16 at% is a = 0.25.
5 to 0.260 nm, c = 0.413 to 0.422 nm
Becomes the value of. It is considered that the lattice matching with the Co alloy used for the second magnetic layer or the third magnetic layer is about 0 to 2%. Therefore, Co of the second magnetic layer to which Pt is added
In order to obtain a good matching state with the alloy, it is preferable that the lattice constants of the CoRu-based alloy, the CoRe-based alloy, the CoIr-based alloy, and the CoOs-based alloy of the first magnetic layer take the above values. Lattice matching is used (lattice constant of Co alloy used for second magnetic layer or third magnetic layer-lattice constant of Co alloy of first magnetic layer) / (second magnetic layer or third magnetic layer). Lattice constant of Co alloy) x 100 (%)
Calculated by

It is preferable that the alloy of the first magnetic layer has a transition temperature from the hcp structure to the fcc structure of 600 ° C. or higher. When forming a magnetic film on a non-magnetic substrate,
Usually, the nonmagnetic substrate is heated to 150 ° C to 300 ° C. Further, since the atoms sputtered during film formation have an energy of about 10 eV, it is presumed that the temperature at which the film collides with the non-magnetic substrate to form a film is even higher.
The transition temperature from the hcp structure of Co to the fcc structure is 42
Since the temperature is 2 ° C., when the nonmagnetic substrate is heated to a high temperature, a part of the deposited Co alloy may have an fcc structure. If the fcc structure increases, the epitaxial growth of the Co alloy is hindered, and the output and the SNR decrease. In order to suppress the ratio of fcc structure, hc
The transition temperature from the p structure to the fcc structure is preferably 600 degrees or higher. Ru, Re, Ir, and Os are preferable because addition of Ru, Re, Ir, and Os can increase the temperature at which the hcp structure transitions to the fcc structure.

In the CoRu alloy, the Ru content is preferably 5 to 30 at% (more preferably 15 to 25 at%). In the CoRe alloy, the Re content is 5 to 30 at% (more preferably 1
It is 5 to 25 at%. ) Is preferable. Co
In the Ir-based alloy, the Ir content is 8 to 30 at%
(More preferably 15 to 25 at%). In the CoOs-based alloy, the content of Os is preferably 5 to 30 at% (more preferably 15 to 25 at%).

The content of each component is Ru: less than 5 at%,
Re: less than 5 at%, Ir: less than 8 at%, Os: 5a
If it is less than t%, the temperature of transition from the hcp structure to the fcc structure is 600 ° C. or less, which is not preferable. Ru: 30
at% or more, Re: 30 at% or more, Ir: 30 at%
As described above, when Os: 30 at% or more, the lattice constant of the Co alloy may exceed a = 0.26 nm, which makes it difficult to achieve lattice matching.

CoRu alloy, Co used for the first magnetic layer
The film thickness of the Re-based alloy, the CoIr-based alloy, and the CoOs-based alloy is preferably 0.5 to 3 nm in any case.
If it is less than 0.5 nm, the epitaxial growth is not sufficient and it becomes difficult to obtain a higher coercive force. If the thickness exceeds 3 nm, the reproduction signal output may be reduced due to antiferromagnetic coupling.

The second magnetic layer or the third magnetic layer may be made of a Co alloy containing Co as a main material and having a hcp structure. For example, CoCrTa alloy, Co
CrPt-based alloy, CoCrPtTa-based alloy, CoCrP
It may include any one selected from tBTa-based alloys and CoCrPtBCu-based alloys.

For example, in the case of CoCrPt type alloy, Cr
Content of Pt is 10-25 at%, Pt content is 8-16
At% is preferable from the viewpoint of SNR.

For example, in the case of CoCrPtB type alloy, C
The content of r is 10 to 25 at% and the content of Pt is 8 to 1
6 at% and B content of 1 to 20 at% is SN
It is preferable from the viewpoint of R.

For example, in the case of CoCrPtBTa type alloy, the Cr content is 10 to 25 at%, the Pt content is 8 to 16 at%, the B content is 1 to 20 at%, and the Ta content is 1 to 4 at%. Is preferable from the viewpoint of SNR.

For example, in the case of CoCrPtBCu alloy, the Cr content is 10 to 25 at%, the Pt content is 8 to 16 at%, the B content is 2 to 20 at%, and the Cu content is 1 to 4 at%. Is preferable from the viewpoint of SNR.

When the magnetic layer is composed of only the first magnetic layer and the second magnetic layer, it is preferable that the thickness of the second magnetic layer is 15 nm or more from the viewpoint of suppressing thermal fluctuation. From the requirement, it is preferably 40 nm or less. 40 nm
If it exceeds, it is difficult to obtain preferable recording and reproducing characteristics.

When the magnetic layer is composed of the first magnetic layer, the second magnetic layer and the third magnetic layer, the thickness of the third magnetic layer is 15 nm.
The above values are preferable from the viewpoint of suppressing thermal fluctuations, but are preferably 40 nm or less in view of the demand for high recording density.
This is because if the thickness exceeds 40 nm, preferable recording / reproducing characteristics cannot be obtained. In this case, the film thickness of the second magnetic layer is 2 to 10
It is preferably nm. If it is less than 2 nm, the magnetization is not sufficient, and if it exceeds 10 nm, it becomes difficult to obtain good antiferromagnetic coupling.

The magnetic layers provided above and below the non-magnetic coupling layer are magnetically coupled by the non-magnetic coupling layer. As an index showing the strength of this bond, Hex (Exchang
ecoupling strength) is used. The magnetic recording medium of the present invention has a Hex value of 800 Oe.
That is all.

Hex is defined as the magnetic field strength from the center of the minor loop to the magnetic field 0 when the minor loop is measured in the coercive force measurement. It can be said that the larger Hex, the stronger and more stable the magnetic coupling between the magnetic layers provided above and below the non-magnetic coupling layer. In addition, the measurement of the minor loop is performed from the magnetic field 0 to the maximum measurement magnetic field (for example, 10000O).
e), the magnetic field is further reversed, and the magnetization curve begins to decrease in the fourth quadrant from the maximum measured magnetic field (eg, 10,000 Oe) to about 1000 Oe (eg, -3000 Oe).
The loop is measured up to e), the magnetic field is further reversed, and from that magnetic field (for example, -3000 Oe) to the maximum measured magnetic field (for example, 10,000 Oe) is measured. At this time, the hysteresis curve observed in the first quadrant of the magnetization curve is a minor loop.

Each magnetic layer may have a multi-layer structure, and the material thereof may be a combination using any one selected from the above. In the case of a multi-layer structure, a CoCrPtBTa-based alloy, CoCrPtBCu-based alloy, or CoCrPtB is formed immediately above the non-magnetic coupling layer.
It is preferable to use a system from the viewpoint of improving the SNR characteristics of the recording / reproducing characteristics. The top layer is CoCrPtB
It is preferable to use a Cu-based alloy or a CoCrPtB-based alloy from the viewpoint of improving the recording / reproducing characteristics and the SNR characteristics.

When the magnetic layer contains B, it is preferable that the Cr concentration is 40 at% or less in the region where the B concentration is 1 at% or more near the boundary between the non-magnetic underlayer and the magnetic layer. Prevents Cr and B from coexisting at a high concentration, and suppresses the formation of a covalent bond compound of Cr and B as much as possible.
As a result, it is possible to prevent the deterioration of the orientation in the magnetic layer due to it.

Further, an orientation adjusting film made of a metal material may be provided between the substrate and the nonmagnetic underlayer for the purpose of promoting the epitaxial growth of the nonmagnetic underlayer. The thickness of the orientation adjusting film is preferably 5 to 50 nm from the viewpoint of promoting epitaxial growth. Further, an adhesion layer may be provided between the non-metal substrate and the orientation adjustment film in order to improve the adhesion between the substrate and the orientation adjustment film. Adhesion layer is Cr, Ti,
Any one selected from W can be used. The thickness of the adhesive layer is 1 to 100 nm (more preferably 5 to 80 nm).
Is. More preferably, it is 7 to 70 nm. It is preferable from the viewpoints of adhesion and productivity. FIG. 3 shows an example in which the orientation adjustment film 301 and the adhesion layer 302 are provided.

For the protective film, a conventionally known material, for example, carbon or SiC alone or a material containing them as a main component can be used. The thickness of the protective film is 1 to 10 nm
Is preferable from the viewpoint of spacing loss or durability when used in a high recording density state.

If necessary, a lubricating layer made of a conventionally known material, for example, a fluorine-based lubricant of perfluoropolyether can be provided on the protective film.

The non-magnetic substrate may have a texture mark on the surface due to the texture treatment.
The average roughness of the surface of the substrate having the texture marks is 0.
1 nm or more and 0.7 nm or less (more preferably 0.1 nm
Above 0.5 nm. More preferably, it is 0.1 nm or more and 0.35 nm or less. ) Is preferably processed. It is preferable that the texture marks are formed substantially in the circumferential direction in order to enhance the magnetic anisotropy in the circumferential direction of the magnetic recording medium. The texture processing can be texture processing with addition of oscillation. Oscillation is an operation of running the tape in the circumferential direction of the substrate and simultaneously swinging the tape in the radial direction of the substrate. Oscillation conditions of 60 to 1200 times / minute are preferable because the amount of surface grinding by the texture becomes uniform. As a method of texture processing, a method of forming a texture mark having a linear density of 7500 [lines / mm] or more can be used, and a method using fixed abrasive grains in addition to the mechanical texture method using the tape described above, A method using a fixed grindstone or a method using laser processing can be used.

The magnetic recording medium of the present invention has a structure in which at least one non-magnetic coupling layer is provided on the non-magnetic underlayer, and the magnetic layer is provided above and below the non-magnetic coupling layer. The first magnetic layer from the side is a CoRu-based alloy, CoRe
One of the alloys selected from the group consisting of Co-based alloys, CoIr-based alloys, and CoOs-based alloys improves the thermal instability and does not reduce the output. It is a magnetic recording medium having a strong magnetic coupling, a high coercive force, and a low noise characteristic suitable for a high recording density.

FIG. 4 shows an example of a magnetic recording / reproducing apparatus using the above magnetic recording medium. The magnetic recording / reproducing apparatus shown here includes a magnetic recording medium 40 having the configuration shown in any of FIGS. 1 to 3, a medium drive unit 41 for rotationally driving the magnetic recording medium 40, and recording / reproducing information on / from the magnetic recording medium 40. A magnetic head 42, a head drive unit 43 for moving the magnetic head 42 relative to the magnetic recording medium 40, and a recording / reproducing signal processing system 44. The recording / reproducing signal processing system 44 can process the data inputted from the outside and send the recording signal to the magnetic head 42, or can process the reproducing signal from the magnetic head 42 and send the data to the outside. ing. In the magnetic head 42 used in the magnetic recording / reproducing apparatus of the present invention, an MR (magnetoresi) that utilizes an anisotropic magnetoresistive effect (AMR) as a reproducing element.
a giant magnetoresistive effect (G)
It is possible to use a head suitable for higher recording density, which has a GMR element utilizing MR).

According to the above magnetic recording / reproducing apparatus, the non-magnetic underlayer has at least one non-magnetic coupling layer, and the magnetic layer is provided above and below the non-magnetic coupling layer. The first magnetic layer from the substrate side is a CoRu-based alloy, C
Since the magnetic recording medium selected from the group consisting of oRe alloy, CoIr alloy, and CoOs alloy is used, the magnetic recording / reproducing apparatus is suitable for high recording density.

Next, an example of the manufacturing method of the present invention will be described.
As a non-magnetic substrate, an Al alloy (hereinafter also referred to as a NiP-plated Al substrate) on which a NiP plating film is formed, which is generally used as a substrate for a magnetic recording medium, or glass, ceramics, silicon, silicon carbide, carbon, resin Of non-metallic material or a substrate of these non-metallic materials on which a film of NiP or NiP alloy is formed is used.

The non-magnetic substrate has an average surface roughness Ra of 2 nm.
It is desirable that it is (20 Å) or less, preferably 1 nm or less.

The surface microwaviness (Wa) is 0.3.
It is preferably not more than nm (more preferably not more than 0.25 [nm]). Chamfer of chamfer part of the end face,
It is preferable for the flight stability of the magnetic head that at least one of the side surface portions has a surface average roughness Ra of 10 nm or less (more preferably 9.5 nm or less). The minute waviness (Wa) can be measured as a surface average roughness in a measurement range of 80 μm using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).

If necessary, the surface of the non-magnetic substrate is textured, the substrate is washed, and the substrate is placed in the chamber of the film forming apparatus. If necessary, the substrate is heated to 100 to 400 ° C. by a heater, for example.

The non-magnetic underlayer 2, the non-magnetic coupling layer and the magnetic layer 4 are formed on the non-magnetic substrate 1 by a DC or RF magnetron sputtering method using a sputtering target made of a material having the same composition as that of each layer. Form.
At this time, before forming the non-magnetic coupling layer, a CoRu-based alloy,
The first magnetic layer is formed from the non-magnetic substrate side made of any one selected from CoRe-based alloy, CoIr-based alloy, and CoOs-based alloy, and the second magnetic layer is formed after forming the non-magnetic coupling layer. . When forming the third magnetic layer, the magnetic layer is formed after forming the second non-magnetic coupling layer before the formation.

The sputtering conditions for forming each film are as follows, for example. The inside of the chamber used for formation is evacuated until the degree of vacuum reaches 10 ⁻⁴ to 10 ⁻⁷ Pa. The substrate is housed in the chamber, and Ar gas, for example, is introduced as a sputtering gas and discharged to perform sputtering film formation. At this time, the power supplied is 0.2 to 2.0 kW, and the desired film thickness can be obtained by adjusting the discharge time and the power supplied.

The nonmagnetic underlayer is formed of Cr, Cr alloy, NiA.
It is formed with a thickness of 5 to 15 nm using a sputtering target made of any one selected from Ru and RuAl.

Next, a CoRu type alloy, a CoRe type alloy,
Using a sputtering target made of any one of CoIr-based alloy and CoOs-based alloy as a raw material, the first
The magnetic layer is formed with a thickness of 0.5 to 3 nm.

Next, Ru, Rh, Ir, Cr, Re, R
u-based alloy, Rh-based alloy, Ir-based alloy, Cr-based alloy, Re
The non-magnetic coupling layer is formed with a sputtering target made of any one selected from the group-based alloys by 0.2 to 1.5.
It is formed to have a thickness of nm (more preferably 0.6 to 1.0 nm).

Next, the second magnetic layer is selected from CoCrPt type alloy, CoCrPtTa type alloy, CoCrPtB type alloy and CoCrPtBY type alloy (Y is at least one selected from Ta and Cu). Using a sputtering target consisting of
It is formed with a thickness of m to 40 nm.

When the third magnetic layer, which is the third magnetic layer, is formed, the magnetic layer is formed in the same manner as described above after the nonmagnetic coupling layer is formed in the same manner as described above. In this case, the second magnetic film is formed with a thickness of 2 to 10 nm, and the third magnetic layer is
It is formed with a thickness of 15 to 40 nm.

An orientation adjustment film is provided between the substrate and the nonmagnetic underlayer.
When an adhesion layer is provided between the non-metal substrate and the orientation adjustment film, it is similarly formed by a sputtering method using a sputtering target using the components of each film as a raw material.

The protective film is formed by a conventionally known sputtering method or plasma CVD method.

The lubricating layer is formed by the conventionally known spin method and dip method.

The magnetic recording medium manufactured by the manufacturing method of the present invention is a magnetic recording medium composed of a nonmagnetic substrate, a nonmagnetic underlayer, a magnetic layer and a protective film, and at least one magnetic recording medium is formed on the nonmagnetic underlayer. The structure has a non-magnetic coupling layer and the magnetic layers are provided above and below the non-magnetic coupling layer, and the first magnetic layer from the non-magnetic substrate side is a CoRu-based alloy, CoRe-based alloy, C
Since the magnetic recording medium is one selected from the oIr alloy and the CoOs alloy, the magnetic recording medium is suitable for high recording density.

Further, according to the manufacturing method of the present invention, since the sputtering target is made of the material having the same composition as the material of each layer, the target is easily formed on the non-magnetic underlayer by the DC or RF magnetron sputtering method. Has a structure in which at least one non-magnetic coupling layer is provided above and below the non-magnetic coupling layer, and the first magnetic layer from the non-magnetic substrate side is a CoRu-based alloy, a CoRe-based alloy, It is possible to manufacture a magnetic recording medium that is any one selected from CoIr-based alloys and CoOs-based alloys.

[0069]

EXAMPLES Hereinafter, the working effects of the present invention will be clarified by showing concrete examples. [Example 1] Aluminum alloy substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 1.270 mm) as a non-magnetic substrate
Then, NiP was applied by electroless plating to a thickness of 12 μm, and the resultant was textured to have an average surface roughness Ra = 0.5 nm. This substrate was set in a DC magnetron sputtering device (C3010 manufactured by Anerva Co.). Vacuum reach 2
^{× 10 - 7 Torr (2.7 ×} 10 - 5 Pa) was evacuated to, and heated to 250 ° C.. As a non-magnetic underlayer, Cr
Using a target consisting of 50 Å and further stacking CrW
A CrW alloy layer was laminated 20Å using a target made of an alloy (Cr: 90 at%, W: 20 at%). First
CoRu alloy (Co15Ru: Ru content 1
It means 5 at%. ) Using a target consisting of
15 Å of oRu alloy was laminated. The non-magnetic coupling layer was 8Å laminated using a target made of Ru. As a second magnetic layer, a CoCrPtB alloy (each content is Co: 60 at)
%, Cr: 22 at%, Pt: 12 at%, B: 6 at
%. Was used to form a CoCrPtB alloy layer, which is a magnetic layer, with a film thickness of 200Å, and a protective film (carbon) of 50Å was laminated. Ar pressure during film formation is 3
It was mTorr. 20 Å of a lubricant made of perfluoropolyether was applied by a dip method to form a lubricating layer.

After that, a glide test was conducted using a glide tester with a glide height of 0.4 μinch as a test condition, and the passed magnetic recording medium was examined for read / write characteristics using a read / write analyzer RWA1632 (manufactured by GUZIK). It was The recording / reproducing characteristics are the reproduction signal output (TAA) and the half-value width of the solitary wave reproduction output (PW5
0), SNR, overwrite (OW), and other electromagnetic conversion characteristics were measured. A composite thin film magnetic recording head having a giant magnetoresistive (GMR) element in the reproducing portion was used for evaluating the recording / reproducing characteristics. Noise is measured from 1 MHz to 500 kFCI when a pattern signal of 500 kFCI is written.
The integrated noise up to the corresponding frequency was measured. Play output 2
It was measured at 50 kFCI and calculated as SNR = 20 × log (reproduction output / integrated noise from 1 MHz to 500 kFCI equivalent frequency). Thermal demagnetization is under the condition of 80 ℃,
The decrease in the reproduction output was measured after 1s, 10s, and 100s, and the result was extrapolated to obtain the output decrease rate after 10 years. The unit is (dB / Decade), which is an index that the reproduction output decreases by this dB in 10 years, and the smaller the value, the better the characteristic. A Kerr effect type magnetic characteristic measuring device (RO1900, manufactured by Hitachi Electronics Engineering Co., Ltd.) was used for measuring the coercive force (Hc), the squareness ratio (S *) and Hex. The evaluation results are shown in Table 1. [Embodiment 2] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co20Ru)
The same process as in Example 1 was carried out except that 10 Å of the target consisting of was laminated. [Embodiment 3] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co20Ru)
The same treatment as in Example 1 was carried out except that a 15 Å laminated target was used. [Embodiment 4] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co20Ru)
The same treatment as in Example 1 was carried out except that a 25 Å laminated target was used. [Embodiment 5] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co25Ru)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Embodiment 6] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRe alloy (Co15Re)
The same treatment as in Example 1 was carried out except that a 15 Å laminated target was used. [Embodiment 7] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRe alloy (Co20Re)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Embodiment 8] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRe alloy (Co25Re)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Embodiment 9] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoIr alloy (Co15Ir)
The same treatment as in Example 1 was carried out except that a 15 Å laminated target was used. [Example 10] The first magnetic layer CoRu alloy (C
o15Ru) instead of CoIr alloy (Co20I
The same process as in Example 1 was carried out except that 20 Å was laminated using the target composed of r). [Embodiment 11] The first magnetic layer CoRu alloy (C
Instead of O15Ru, CoIr alloy (Co25I)
The same process as in Example 1 was carried out except that 20 Å was laminated using the target composed of r). [Embodiment 12] The first magnetic layer CoRu alloy (C
o15Ru) instead of CoOs alloy (Co15O
The same treatment as in Example 1 was carried out except that 15 Å was laminated using the target consisting of s). [Example 13] First magnetic layer CoRu alloy (C
Instead of o15Ru) CoOs alloy (Co20O
The same treatment as in Example 1 was carried out except that 20 Å was laminated using the target consisting of s).

Example 14 A glass substrate (outer diameter 65 mm, inner diameter 20 mm, thickness 0.635 m) as a non-magnetic substrate
m, surface roughness 3Å) was set in a DC magnetron sputtering device (C3010 manufactured by Anerva Co.). Ultimate vacuum degree of ^{2 × 10 - 7 Torr (2.7} × 10 - 5 Pa) was evacuated to, and heated to 250 ° C.. As a non-magnetic underlayer, a RuAl alloy (Ru: 50 at%, Al: 50 at)
%) Is used to stack 300Å and a CrTi alloy (Cr: 90 at%, Ti: 20 at%)
A CrTi alloy layer was laminated by 50 Å using a target made of. A CoRu alloy (Co20Ru:
Ru content 20 at%. 20 Å of a CoRu alloy was laminated using a target made of (1). The nonmagnetic coupling layer is Ru
8Å was laminated using a target consisting of As the second magnetic layer, a CoCrPtB alloy (Co: 60 at%, Cr:
22 at%, Pt: 12 at%, B: 6 at%) is used to form a CoCrPtB alloy layer which is a magnetic layer with a thickness of 200 Å, and a protective film (carbon) 50
Å laminated. The Ar pressure during film formation was 3 mTorr.
20 Å of a lubricant made of perfluoropolyether was applied by a dip method to form a lubricating layer. [Example 15] Instead of the first magnetic layer CoRu alloy (Co20Ru) of Example 14, a CoRu alloy (Co20) was used.
The same treatment as in Example 14 was carried out except that 20 Å was laminated using a target composed of Re). [Example 16] Instead of the first magnetic layer CoRu alloy (Co20Ru) of Example 14, a CoIr alloy (Co20) was used.
The same process as in Example 14 was carried out except that 20 Å was laminated using a target made of Ir). [Example 17] Instead of the first magnetic layer CoRu alloy (Co20Ru) of Example 14, a CoOs alloy (Co20) was used.
The same treatment as in Example 14 was performed except that a 20 Å layer was stacked using a target made of Os).

[Embodiment 18] In Embodiment 1, the thickness of the second magnetic layer is set to 30 Å, and another layer as a non-magnetic coupling layer, a target made of Ru, is used immediately above the second magnetic layer.
Å Laminate the CoCrPtB alloy (C
o: 60 at%, Cr: 22 at%, Pt: 12 at
%, B: 6 at%), and the same treatment as in Example 1 was performed except that the CoCrPtB alloy layer as the magnetic layer was formed to a thickness of 200 Å.

[Comparative Example 1] An aluminum alloy substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 1.2) as a non-magnetic substrate.
70 mm) was coated with NiP by 12 μm by electroless plating and textured to have an average surface roughness Ra = 0.5 nm. This substrate was set in a DC magnetron sputtering device (C3010 manufactured by Anerva Co.). The ultimate vacuum degree of ^{2 × 10 - 7 Torr (2.7} × 10 - 5 Pa)
After evacuating to 250 ° C., it was heated to 250 ° C. As the non-magnetic underlayer, a target made of Cr is used to stack 50Å and further CrW alloy (Cr: 90 at%, W: 20 at%)
A CrW alloy layer of 20 Å was laminated using a target composed of. Furthermore, a CoCr alloy (Co:
A CoCr alloy was laminated by 15 Å using a target composed of 65 at% and Cr: 35 at%). CoCrPtB alloy (Co: 60 at%, Cr: 22a) is used for the first magnetic layer.
20% of a CoCrPtB alloy was laminated using a target composed of t%, Pt: 12 at%, B: 6 at%).
The non-magnetic coupling layer is 8Å using a target made of Ru.
Laminated. CoCrPtB alloy (C
o: 60 at%, Cr: 22 at%, Pt: 12 at
%, B: 6 at%) was used to form a CoCrPtB alloy layer as a magnetic layer with a film thickness of 200 Å, and a protective film (carbon) of 50 Å was laminated. A at the time of film formation
The r pressure was 3 mTorr. 20 Å of a lubricant made of perfluoropolyether was applied by a dip method to form a lubricating layer. [Comparative Example 2] First magnetic layer CoCrPtB alloy of Comparative Example 1 (Co: 60 at%, Cr: 22 at%, Pt: 12 a)
t%, B: 6 at%)
The same treatment as in Comparative Example 1 was carried out except that a CrPtB alloy of 40 Å was laminated. Comparative Example 3 First magnetic layer CoCrPtB alloy of Comparative Example 1 (Co: 60 at%, Cr: 22 at%, Pt: 12 a
t%, B: 6 at%)
The same treatment as in Comparative Example 1 was carried out except that a CrPtB alloy was laminated by 60 liters. [Comparative Example 4] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co20Ru)
The same treatment as in Example 1 was carried out except that 40 Å was laminated using the target consisting of. [Comparative Example 5] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co20Ru)
The same process as in Example 1 was carried out except that a target consisting of 60 Å was laminated. Comparative Example 6 First magnetic layer CoRu alloy (Co
15Ru) instead of CoRu alloy (Co40Ru)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Comparative Example 7] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoIr alloy (Co40Re)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Comparative Example 8] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoIr alloy (Co40Ir)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated. [Comparative Example 9] The first magnetic layer CoRu alloy (Co
15Ru) instead of CoOs alloy (Co40Os)
The same process as in Example 1 was carried out except that 20 Å of the target consisting of was laminated.

[Comparative Example 10] A glass substrate (outer diameter 65 mm, inner diameter 20 mm, thickness 0.635 m) as a non-magnetic substrate.
m, surface roughness 3Å) was set in a DC magnetron sputtering device (C3010 manufactured by Anerva Co.). Ultimate vacuum degree of ^{2 × 10 - 7 Torr (2.7} × 10 - 5 Pa) was evacuated to, and heated to 250 ° C.. As a non-magnetic underlayer, a RuAl alloy (Ru: 50 at%, Al: 50 at)
%) Is used to stack 300Å and a CrTi alloy (Cr: 90 at%, Ti: 20 at%)
A CrTi alloy layer was laminated by 50 Å using a target made of. Further, a CoCr alloy (C
O: 65 at%, Cr: 35 at%) was used to deposit a 15 Cr CoCr alloy. CoCrPtB alloy (Co: 60 at%, Cr: 2) is used for the first magnetic layer.
A CoCrPtB alloy was laminated at 20Å using a target composed of 2 at%, Pt: 12 at% and B: 6 at%). The non-magnetic coupling layer was 8Å laminated using a target made of Ru. As a second magnetic layer, a CoCrPtB alloy (Co: 60 at%, Cr: 22 at%, Pt: 12 a
tCo, B: 6 at%) was used to form a CoCrPtB alloy layer as a magnetic layer with a film thickness of 200 Å, and a protective film (carbon) of 50 Å was laminated. A at the time of film formation
The r pressure was 3 mTorr. 20 Å of a lubricant made of perfluoropolyether was applied by a dipping method to form a lubricating layer. [Comparative Example 11] First magnetic layer CoCrPtB of Comparative Example 10
Alloy (Co: 60 at%, Cr: 22 at%, Pt: 1
2 at%, B: 6 at%) was used, and the same treatment as in Comparative Example 1 was performed except that a CoCrPtB alloy of 40 Å was stacked. [Comparative Example 12] First magnetic layer CoCrPtB of Comparative Example 10
Alloy (Co: 60 at%, Cr: 22 at%, Pt: 1
2 at%, B: 6 at%) was used, and the same treatment as in Comparative Example 1 was performed except that a CoCrPtB alloy was laminated at 60 Å using a target.

[Comparative Example 13] In Comparative Example 1, the thickness of the second magnetic layer was set to 30 Å, and one layer as a non-magnetic coupling layer, 8 Å was laminated using a target made of Ru immediately above the third magnetic layer. CoCrPtB alloy (Co: 6
0 at%, Cr: 22 at%, Pt: 12 at%, B:
6 at%) and a magnetic layer of C
The same process as in Example 1 was performed except that the oCrPtB alloy layer was formed to have a film thickness of 200Å.

Various measurements were carried out on each of the obtained magnetic recording media in the same manner as in Example 1, and the results are shown in Table 1.

Table 2 shows the lattice constant of each film.

[0078]

[Table 1]

[0079]

[Table 2]

As compared with Comparative Example 1, Examples 1 to 13 have higher coercive force, and are superior in SNR, thermal demagnetization, and Hex. In Comparative Examples 2 to 4, the thickness of the first magnetic layer is increased to improve the thermal demagnetization characteristics, but as a result, it can be seen that the output and Hex are reduced. In Comparative Examples 6 to 9, since the CoRu-based alloy, the CoRe-based alloy, the CoIr-based alloy, and the CoOs-based alloy have almost no magnetization, the coercive force, output, SNR,
It can be seen that the results are all inferior such as thermal demagnetization. Note that Hex cannot be measured because there is almost no magnetization. Since Examples 14 to 17 are isotropic media, their characteristics are lower than those of the other Examples. However, compared with Comparative Example 10 which is the same isotropic medium, coercive force is high, and SNR and thermal loss are low. It can be seen that magnetism and Hex are excellent. Comparative Examples 11 and 12 are isotropic media in which the thickness of the first magnetic layer is increased to improve the property of thermal demagnetization, but as a result, the output and Hex are reduced. You can see that

[0081]

The magnetic recording medium of the present invention has a structure in which at least one non-magnetic coupling layer is provided on the non-magnetic underlayer, and the magnetic layer is provided above and below the non-magnetic coupling layer. The first magnetic layer from the magnetic substrate side is a CoRu-based alloy, CoR
Since the magnetic recording medium is characterized by being selected from the group consisting of e-based alloys, CoIr-based alloys, and CoOs-based alloys, it has a higher coercive force and a square shape even if the first magnetic layer has a thinner film thickness. Since the ratio can be expressed and the thermal stability is improved without lowering the output, the magnetic recording medium is suitable for high recording density.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing another embodiment of the magnetic recording medium of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the magnetic recording medium of the present invention.

FIG. 4 is a schematic configuration diagram showing an example of a magnetic recording / reproducing apparatus using the magnetic recording medium of the present invention.

FIG. 5 is a cross-sectional view showing an embodiment of an AFC medium using two conventional magnetic layers.

FIG. 6 is a cross-sectional view showing an embodiment of an AFC medium using three conventional magnetic layers.

[Explanation of symbols]

101: non-magnetic substrate, 102: non-magnetic underlayer, 103:
First magnetic layer, 104: non-magnetic coupling layer, 105: second magnetic layer, 106: protective film, 107: lubricating layer, 202: third magnetic layer, 301: orientation adjusting film, 302: adhesion layer, 40: magnetic Recording medium, 41; medium driving unit, 42: magnetic head, 4
3: head drive unit, 44: recording / reproducing signal processing system, 50
1: non-magnetic substrate, 502: non-magnetic underlayer, 503: non-magnetic intermediate layer, 504: first magnetic layer, 505: non-magnetic coupling layer, 506: second magnetic layer, 507: protective film, 508: lubricating layer 601: Non-magnetic substrate, 602: Non-magnetic underlayer, 603:
Non-magnetic intermediate layer, 604: first magnetic layer, 605: non-magnetic coupling layer, 606: second magnetic layer, 607: non-magnetic coupling layer, 6
08: third magnetic layer, 609: protective film, 610: lubricating layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 5/851 G11B 5/851 H01F 10/16 H01F 10/16 10/28 10/28 10/30 10 / 30 F term (reference) 4K029 AA02 AA06 AA09 AA24 BA21 BA24 BB02 BB07 BC06 BD11 EA01 FA07 5D006 BB01 BB07 BB08 CA01 CA05 CB04 DA03 EA03 FA09 5D112 AA02 AA03 AA05 BA04 BA04 BD04 A04 BA04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD02 BD04 BD04 BD04 BD04 BD02 BD04 BD04 BD02 BD04 BD04 BD04 BD04 BD02 BD04 BD04 BD04 BD02 BD04 BD04 BD02 BD04 BD04 BD04 BD02 BD04 BD04 BD02 BD04 BD04 BD02 BD04 BD04 BD02 BD04 BD02 BD02 BD04 BD02 BD04 BD02 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD04 BD02 B04 BD04 B04 BD04 BD04 BD02 BD02 BD04 BD04 BD02 BD04 BD04 BD04 BD02 BD04 BD04 BD02 BD $ 000 MB.

Claims (13)

[Claims] 1. A magnetic recording medium comprising at least a non-magnetic substrate, a non-magnetic underlayer, a magnetic layer and a protective film, wherein at least one non-magnetic coupling layer is provided on the non-magnetic under layer, and the non-magnetic coupling layer comprises the non-magnetic coupling layer. The first magnetic layer from the nonmagnetic substrate side has a structure provided above and below the layer, and the first magnetic layer is a CoRu-based alloy, C
A magnetic recording medium, which is one selected from an oRe alloy, a CoIr alloy, and a CoOs alloy. 2. The lattice constant of the alloy of the first magnetic layer is a = 0.25 nm to 0.26 nm, and c = 0.407n.
The magnetic recording medium according to claim 1, wherein m is 0.422 nm. 3. The magnetic recording medium according to claim 1, wherein the alloy of the first magnetic layer has a transition temperature from the hcp structure to the fcc structure of 600 ° C. or higher. 4. When the alloy of the first magnetic layer is a CoRu-based alloy, the Ru content is 5 to 30 at%, and when the alloy is a CoRe-based alloy, the Re content is 5 to 30 at%, and CoIr.
In the case of a system alloy, the Ir content is 8 to 30 at%, CoO
4. The magnetic recording medium according to claim 1, wherein the s-based alloy has an Os content of 5 to 30 at%. 5. The film thickness of the first magnetic layer is 0.5 to 3 nm.
The magnetic recording medium according to any one of claims 1 to 4, wherein 6. The nonmagnetic coupling layer comprises Ru, Rh, Ir, C
r, Re, Ru-based alloy, Rh-based alloy, Ir-based alloy, Cr
The magnetic recording according to any one of claims 1 to 5, which is one kind selected from a group-based alloy and a Re-based alloy and has a film thickness of 0.5 to 1.5 nm. Medium. 7. The magnetic property has anisotropy in the circumferential direction with respect to a non-magnetic substrate, and the non-magnetic underlayer comprises Cr or C.
C consisting of r and one or more selected from Ti, Mo, Al, Ta, W, Ni, B, Si and V
7. The magnetic recording medium according to claim 1, which has a multi-layer structure including a layer made of any one of r alloys. 8. A magnetic property is in-plane isotropic with respect to a non-magnetic substrate, and the non-magnetic underlayer is a NiAl-based alloy, R
uAl-based alloy, or Cr and Ti, Mo, Al, Ta,
7. A multi-layer structure including a layer made of any one of Cr alloys selected from W, Ni, B, Si and V or at least two kinds. 7. The magnetic recording medium according to 1. 9. The magnetic recording medium according to claim 1, wherein the non-magnetic substrate is any one selected from a glass substrate and a silicon substrate. 10. The non-magnetic substrate is one in which a surface of any one selected from an Al substrate, a glass substrate, and a silicon substrate is plated with NiP, and the non-magnetic substrate is characterized in that. The magnetic recording medium described. 11. The second magnetic layer or the third magnetic layer is a CoCrPt-based alloy, a CoCrPtTa-based alloy, or C.
oCrPtB-based alloy, CoCrPtBY-based alloy (Y is T
Any one or more selected from a and Cu. 1) any one selected from the above.
11. The magnetic recording medium according to any one of items 1 to 10. 12. A method of manufacturing a magnetic recording medium, comprising the steps of forming a nonmagnetic underlayer on a nonmagnetic substrate, forming a magnetic layer, and forming a protective film. A step of forming at least one non-magnetic coupling layer on the top, and prior to the step, the first step consisting of any one selected from CoRu alloy, CoRe alloy, CoIr alloy and CoOs alloy A method of manufacturing a magnetic recording medium, comprising: a step of forming a magnetic layer; and a step of forming a second magnetic layer after forming a nonmagnetic coupling layer. 13. A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is any one of claims 1 to 11. Magnetic recording / reproducing apparatus characterized by being a magnetic recording medium of.