JPH0729144A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To set a combination of the coercive force and the squareness ratio at a desired optimum value, by adjusting the coercive force of a magnetic layer of Co alloy laminated on an undercoat of Cr alloy and the squareness ratio within a predetermined range. CONSTITUTION:A non-magnetic substrate 1 constitutes a glass disc. The substrate 1 and a sputtering target are set in a chamber of an RF magnetron sputtering device, when the pressure is reduced. While the substrate is kept at a specific temperature, Ar gas is introduced into the chamber to form a non-magnetic undercoating layer 2 by sputtering. Similarly, a layer 3 of Co, Pt, Cr and Mo alloy is formed on the undercoating layer 2 using Ar gas as a sputtering gas and a target of Co, Pt, Cr and Mo. A protecting layer 4 is formed with the use of a carbon plate as a target. Then, a lubricant layer 5 is applied on the protecting film 4, whereby a magnetic recording medium 6 is formed. The coercive force of the magnetic layer of Co alloy laminated on the undercoat of Cr alloy and the squareness ratio can be set at desired optimum values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for a hard disk device which is a magnetic storage device having a large capacity and capable of high speed access.

[0002]

2. Description of the Related Art In recent years, as the speed and capacity of information processing devices have increased, the speed and capacity of hard disk devices forming a part of main memory have been continuously increased. High-density magnetic recording is indispensable for increasing capacity. For this reason, thin-film magnetic recording technology using a thin-film alloy structure has made rapid progress.

In particular, Co-based metal, which has a hexagonal crystal structure and exhibits a strong magnetocrystalline anisotropy in the c-axis direction, has attracted attention as a high-density magnetic material. Co itself has the c-axis as the easy axis of magnetization, but the magnetization is too large and the maximum demagnetizing field is slightly larger than the magnetocrystalline anisotropy. Therefore, the maximum demagnetizing field is made smaller than the magnetocrystalline anisotropy by mixing with an appropriate non-magnetizable element to form an alloy.

In order to enable high density horizontal recording,
It is necessary to have a crystal growth in the form of particles (columnar to the film surface) so that the film has a c-axis orientation component in the film plane, and to obtain an alloy thin film with sufficiently high adhesion to the substrate. Is. For this reason, physical vapor deposition methods such as sputtering and ion plating have been developed in place of the conventional wet coating method. In these physical vapor deposition methods, by performing heat treatment at an appropriate temperature during or after vapor deposition, crystals can be rearranged to enhance homogeneity and improve coercive force Hc. Coercive force is one of the important characteristics in magnetic recording. If the coercive force is small, the external disturbing magnetic field disturbs the recording, but if the coercive force is too large, recording cannot be performed unless the input signal to the coil of the head is increased or a material having a high saturation magnetic flux density is used for the head core.

Another important characteristic of magnetic recording media is the squareness ratio. The squareness ratio refers to the ratio of residual magnetization Br to saturation magnetization Bs, Br / Bs, which is large (1
The closer to), the larger the signal output during reproduction can be. The residual magnetization is large because the magnetic anisotropy energy in that direction is sufficiently larger than the energy in other directions. That is, in the case of the Co-based magnetic body in which the c-axis is the easy axis of magnetization, the residual magnetization tends to increase as the c-axis orientation increases in the film plane.

Among Co-based alloy thin film media, Co-Pt-based alloys have been known as magnetic materials exhibiting high saturation magnetization Bs, high coercive force and corrosion resistance. It has been reported that Hc and Bs can be controlled over a wide range by adding one selected from the group consisting of some of the group IV and group V elements (Yamaguchi et al .;
Journal of Television Society, Volume 40, No. 6, 475-48
0 page, published in 1986). In addition, a Co—Ni—Cr alloy magnetic layer was deposited on a glass (or NiP / Al) substrate to form C.
When physical vapor deposition was performed on the r-based metal underlayer, the magnetic layer was epitaxially grown on the underlayer, and it was shown that Hc was influenced by the composition of the underlayer, that is, the kind and mixing concentration of elements forming an alloy with Cr. (N. Tani et a
l; J. Appl. Phys. 67 / (12) pp.
7507-7509 (1990)).

Further, a Co-Pt alloy magnetic layer is physically vapor-deposited on a Cr-based alloy (CrV or CrFe) underlayer, and the lattice constant of the alloy underlayer is changed to change the c-axis orientation of the magnetic layer in the film plane. Has been reported to improve Hc and squareness ratio (Japanese Patent Publication No. 4-16848).

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
It is disclosed that the magnetic properties of the Co-based alloy magnetic layer are influenced by the composition of the Cr-based alloy underlayer and Hc and squareness (or saturation magnetization) are improved. It is also suggested that these changes in properties are related to the c-axis orientation of the deposited magnetic layer alloy particles.

However, it has been a problem to enhance the c-axis orientation of the magnetic layer alloy particles only in the film plane, and in fact, only the improvement of the squareness ratio is aimed at, and the sufficiently high coercive force Hc and the squareness ratio Br / It cannot be said that the combination of Bs has been obtained. For example, Japanese Patent Publication No. 4-16848 described above does not disclose a technique capable of controlling the distribution of c-axis oriented particles oriented in the vertical direction from the film surface, and as a result, Co-P
In some cases, the composition cannot be controlled to obtain a desired combination of Hc and Br / Bs in the t-based magnetic layer. In particular, when the Pt content is reduced from the economical point of view, the composition range in which the c-axis orientation can be controlled is further reduced, and it is difficult to optimize the Hc and the squareness ratio.

The object of the present invention is to provide a coercive force Hc and a squareness ratio Br / B of a Co-based alloy magnetic layer laminated on a Cr-based alloy underlayer.
It is to provide a relatively inexpensive magnetic recording medium in which the combination of s is controlled to a desired optimum value.

[0011]

One of the problems of the above-mentioned prior art is that the relationship between the c-axis orientation distribution of the magnetic layer alloy particles and the coercive force Hc and the squareness ratio has not been comprehensively understood. Another reason is that the method for effectively controlling the vertical direction of the c-axis orientation distribution has not been developed.

In the present invention, by using the X-ray diffraction method, the relationship between the coercive force and the squareness ratio of the c-axis orientation distributed in the perpendicular direction from the film surface of the magnetic layer is obtained, and the underlayer and the magnetic layer are formed. Pt that satisfies a desired combination of Hc and squareness by adjusting the composition within a predetermined c-axis orientation pattern
A magnetic recording medium having a small compounding ratio was obtained.

That is, according to the present invention, at least (1) a nonmagnetic underlayer containing Cr and a nonmagnetic element X having a larger atomic radius than Cr, and (2) Co and Co.
A magnetic layer containing a non-magnetic element Y having a larger atomic radius is laminated in this order, and the c-axis orientation distribution of the magnetic particles forming the magnetic layer is the element X contained in the non-magnetic underlayer. Is a function of the compounding concentration x, and the compounding concentration y of the element Y has a c-axis orientation transition region that transitions from the vertical orientation type to the in-plane orientation type on the magnetic layer film surface as x increases. And a magnetic recording medium characterized by selecting the above-mentioned x.

In the magnetic recording medium of the present invention, the relation between x and y may be selected so that the c-axis orientation distribution falls within the c-axis orientation transition region when y is selected as a predetermined value. preferable. In the magnetic recording medium of the present invention,
The magnetic layer is preferably an alloy layer further containing Pt and Cr.

In the magnetic recording medium of the present invention, the element X is preferably at least one selected from the group consisting of Mo, Al, Ti, Zr, Nb, Hf, Ta and W. In the magnetic recording medium of the present invention, the element Y is Mo, Al, V, Zr, Nb, Hf, Ta.
It is preferably at least one selected from the group consisting of and W.

In the magnetic recording medium of the present invention, the more preferable composition of each element is that the Cr in the non-magnetic underlayer is 4 or less.
0 atomic% or more and less than 100 atomic%, Co in the magnetic layer is 70
It is preferable that the content is not less than atomic% and not more than 90 atomic%. When the magnetic layer contains Pt and Cr, Pt in the magnetic layer is 4
It is preferable that the content of Cr is 2 atomic% or more and 20 atomic% or less, and the content of Cr is 2 atomic% or more and 16 atomic% or less. Further, it is preferable that the element X is 60 atomic% or less and the element Y is 20 atomic% or less.

According to the present invention, the non-magnetic element X contained in the non-magnetic underlayer and the non-magnetic element Y contained in the magnetic layer have atomic radii larger than those of Cr and Co, which are the main components of each layer. This increases the lattice constant of each layer by alloying these elements. The amount of change in the lattice constant is determined by the values of x and y, which are the compounding amounts of the elements X and Y. Therefore, by selecting appropriate X, Y, x, and y, the lattice matching between the non-magnetic underlayer and the magnetic layer can be achieved. be able to. As a result, the c-axis orientation distribution of the magnetic layer particles can be appropriately controlled, and a magnetic recording medium having a higher coercive force and squareness ratio than before can be obtained in a composition having a low platinum compounding ratio.

Next, the preferable blending amount of each element in the magnetic recording medium of the present invention will be described. When Co, which is the main component of the magnetic layer, is less than 60 atomic%, the magnetizing ability is deteriorated and the desired residual magnetization Br cannot be obtained. Conversely, 9
If it exceeds 0 atomic%, the content of Pt and Cr, which are other components, becomes 10 atomic% or less, and the coercive force Hc cannot be sufficiently increased. Therefore, Co is 60 to 90 atomic%
Is preferred, and when considering both Hc and Br, it is especially 70-
86 atom% is preferable.

On the other hand, Pt in the magnetic layer is added in order to increase Hc without reducing Br, but if the amount is less than 4 atom%, the effect is small, and if it exceeds 20 atom%, B is increased.
In addition to reducing r, it is not preferable from an economical point of view. Therefore, the compounding amount of Pt is preferably 4 to 20 atomic%, and
Considering both r and Hc, particularly preferably 5 to 16
It is in the atomic% range.

Further, Cr mixed in the magnetic layer has an action of increasing Hc by heating during or after the formation of the magnetic layer. If the content is less than 2 atomic%, the effect is small, and if it exceeds 16 atomic%, Br is lowered. Therefore, 2 to 16 atomic% is preferable, and 6 to 14 atomic% is preferable in consideration of both Br and Hc.

Further, the element Y (Mo,
Al, Ti, V, Zr, Nb, Hf, Ta, W) changes the lattice constant of the magnetic layer and controls the coercive force and squareness ratio, but when it exceeds 20 atomic%, Br decreases. 20 atomic% or less is preferable, and 1 to 14 atomic% is particularly preferable in view of Br, squareness ratio, Hc and the like.

Next, Cr, which is the main component of the underlayer, is a non-magnetic atom and is included because it has excellent adhesion to the substrate and the magnetic layer. However, if the compounding amount is less than 40 atomic%, the adhesion is improved. , Becomes unsuitable from the viewpoint of lattice matching, 100
At atomic%, the element X cannot be contained, and the coercive force,
Since the squareness ratio cannot be increased, it is preferably 40 atomic% or more and less than 100 atomic%, and particularly preferably 70 to 90 atomic%.

The element X (Mo, A added to the underlayer)
(l, Ti, V, Zr, Nb, Hf, Ta, W) has the effect of changing the lattice constant of the underlayer to control the coercive force and the squareness ratio, but the compounding amount of 60 atomic% or less is preferable. 60
This is because if the atomic percentage is exceeded, the lattice constant becomes too large and lattice matching with the magnetic layer is impossible. Considering Br, Hc, squareness ratio, etc., X is preferably 1 to 30 atom%.

The film formation by physical vapor deposition is 100 ° C. to 4 ° C.
If the heating is performed at 00 ° C., the rearrangement becomes easy, and therefore the c-axis orientation can be controlled without being affected by the film forming conditions (sputtering, gas pressure, film forming rate, vacuum degree, etc.). In addition to being capable of increasing the coercive force, it is preferable. The c-axis orientation is dominated by the film forming conditions in the low temperature film formation in which the substrate temperature is less than 100 ° C., and the coercive force becomes small in the case of heating above 400 ° C. It is considered that this is because the crystal grains of Cr become large. Note that after the film formation, heating may be performed at higher than 400 ° C.

[0025]

FIG. 1 is a diagram showing the layer structure of a magnetic recording medium in an embodiment of the present invention. In the figure, the non-magnetic substrate 1
Is a glass disk having a diameter of 65 mmφ and a thickness of 0.9 mm. The substrate 1 and the sputtering target are loaded into the chamber of the RF magnetron sputtering apparatus, and the pressure is reduced to a vacuum degree of 5 × 10 ⁻⁷ Torr or less. Next, the substrate temperature is maintained at 300 ° C., and Ar gas is set to 20.
It was introduced into the chamber with a partial pressure of mTorr, and the nonmagnetic underlayer ² was first formed by sputtering with an input power density of 2.5 W / cm ² . For the sputtering of the non-magnetic underlayer 2, a CrMo alloy layer having a thickness of 100 nm was formed using a sputtering target of 90 atomic% Cr and 10 atomic% Mo.

Similarly, a target having a composition of 77 atomic% Co, 9 atomic% Pt, 10 atomic% Cr and 4 atomic% Mo was used with argon as a sputtering gas to form a 40 nm thick CoPtCrMo alloy layer on the non-magnetic underlayer 2. Filmed Next, similarly, argon was used as a sputtering gas, a carbon plate was used as a target, and a film thickness of 40
A protective layer 4 having a thickness of 4 nm was formed.

After forming the protective layer 4, the sample is taken out of the sputtering apparatus, and the protective layer 4 is coated with a lubricating layer 5 made of perfluoropolyether having a thickness of 2 nm to form a magnetic recording medium 6.
Got When the magnetic characteristics of this magnetic recording medium were measured, the coercive force was 1750 (Oe) and the squareness ratio was 0.78.

As a comparative example to Example 1, a magnetic recording medium in which Mo is not added to the non-magnetic underlayer alloy and the magnetic layer alloy (Comparative Example 1) and a magnetic recording medium in which Mo is not added to the magnetic layer alloy (Comparative Example 2) A magnetic recording medium (Comparative Example 3) in which Mo was not added to the non-magnetic underlayer alloy was prepared, and the coercive force and the squareness ratio were measured.

[0029]

[Table 1]

As is clear from Table 1, in Comparative Example 2 in which Mo is mixed only in the non-magnetic underlayer, the squareness ratio is improved, but the coercive force is decreased, as compared with the case where Mo is not mixed at all.
Further, in Comparative Example 3 in which Mo is mixed only in the magnetic layer, both the squareness ratio and the coercive force decrease. On the other hand, in the case of this example in which both layers are mixed with Mo, it is understood that both the coercive force and the squareness ratio are improved.

The two magnetic layer compositions shown in Table 1, that is, Co ₈₁ Pt ₉ Cr containing no non-magnetic element Y (= Mo)
_In each case of the composition Co ₇₈ Pt ₉ Cr ₉ Mo ₄ in which ₁₀ and the non-magnetic element Y (= Mo) were replaced by a part of Co and Cr, the change in the composition of the non-magnetic underlayer (the non-magnetic element X ( The effect of the composition ratio of Mo) on the magnetic characteristics of the magnetic layer was measured. The obtained results are shown in FIGS. 2 and 3, respectively.

In any case, the nonmagnetic underlayer tends to increase the squareness ratio Br / Bs as the amount x of the nonmagnetic element X (= Mo) to be mixed increases, but the coercive force Hc behaves differently. . That is, Hc is Y (= Mo) in the magnetic layer.
In the case of blending, the peak value is shown as x increases,
Without Y, x simply decreases with increasing.

In order to investigate the reason for this, the c-axis orientation distribution of the magnetic layer particles was measured in each case using the pole analysis method by X-ray diffraction. CuKα rays (λ = 1.5405A) with an accelerating voltage of 50 kV were irradiated to the sample processed to 15 mmφ, and X-ray diffraction was performed by the Schulz reflection method to obtain data for pole analysis. The slit is D.I. S. =
1.0 degree, S.I. S. = 6.0 mm, R.I. S. = 6.0 m
m. The measurement angle range is 20 to 90 degrees. Since the X-ray diffraction was performed by using the reflection method, the measurement was not performed at 20 degrees or less. The measurement angle interval was such that the angle α from the film surface in the vertical direction was 5.0 degrees and the angle β in the film surface was 5.0 degrees. The measurement time is 5.00 seconds for each measurement point.

X-ray diffraction was performed on Co (002), (100) and (101) having a hexagonal crystal structure. The c-axis orientation distribution at α = 20 to 90 degrees is (00
2), the c-axis orientation distribution at α <20 degrees is Co
Calculated from (100) and Co (101). Based on these data, the c-axis orientation distribution at the angle θ from the film surface to the vertical direction was determined.

C of the magnetic layer particles corresponding to FIGS. 2 and 3.
The angle θ dependence of the axial orientation distribution is shown in FIG. 4 and FIG. 5, respectively.
Shown in. FIG. 4 shows a magnetic layer Co ₈₁ Pt ₉ C containing no Mo.
It is a c-axis orientation distribution examined for two cases in which r ₁₀ has different non-magnetic underlayer compositions. FIG. 4A shows the case of x = 0, that is, the case of the Cr underlayer, and FIG. 4B shows x = 20 atomic%.
That is, the case of Cr ₈₀ Mo ₂₀ underlayer. Although these two figures are shown as representative examples, it can be seen that the c-axis orientation distribution of the magnetic layer particles concentrates in the magnetic layer film surface as the Mo content x of the nonmagnetic underlayer increases. This tendency corresponds to the coercive force Hc monotonically decreasing as x increases.

On the other hand, FIG. 5 shows a magnetic layer C containing 4 atomic% of Mo.
It shows the effect of the composition of the non-magnetic underlayer on the c-axis orientation distribution of o ₇₈ Pt ₉ Cr ₉ Mo ₄ . This figure shows three typical underlayer compositions, that is, x =
Cr underlayer 0 (FIG. 5 (a)), x = 10 atomic% of Cr ₉₀ Mo ₁₀ underlayer Hc exhibits a peak in Figure 3 (Fig. 5
(B)), and x = 20 corresponding to the Hc decreasing region in FIG.
5 shows the c-axis orientation distribution for an atomic% Cr ₈₀ Mo ₂₀ underlayer (FIG. 5 (c)). 5 (a), (b), and (c)
As x increases, the direction perpendicular to the film surface (θ = 90)
C-axis oriented particles distributed in the magnetic layer film surface (θ =
It shows that the distribution gradually changes to 0 degree). Then, it can be seen that Hc shows a peak in the transition region (FIG. 5B) in the middle. In the transition region, the proportion of c-axis oriented particles having an intermediate angle of 40 ° ≦ θ ≦ 70 ° is high.

Comparing the data of FIGS. 2 to 5, the following can be considered. Both the magnetic layer and the non-magnetic underlayer are Mo
When not including (when x = y = 0, Comparative Example 1),
The lattice constant of the underlayer Cr is slightly larger than that of the magnetic layer, and compressive strain is applied to the magnetic layer. Underlayer alloying (element X
If the lattice constant is further increased due to the (composition of), the compressive strain of the magnetic layer becomes even larger. In such a case, the c-axis of the magnetic layer particles is distributed in the film surface, and Hc decreases according to the magnitude of compressive strain. Next, when the element Y is added to the magnetic layer to make the lattice constant larger than that of the underlayer, tensile strain is applied to the magnetic layer. At this time, the magnetic layer particles tend to be c-axis oriented in the direction perpendicular to the film surface. In this state, when the element X is mixed in the underlayer to increase the blending amount x of the element X, the tensile strain is gradually relaxed and eventually the strain becomes small (or strain-free). As the strain becomes smaller, Hc increases, and along with this, the c-axis orientation is disturbed and enters the above-mentioned “transition region”. Hc shows a peak when the strain is the smallest. When x is further increased, the lattice constant of the underlayer becomes larger than that of the magnetic layer, and it turns into compressive strain. In this region, the c-axis of the magnetic layer grains has stronger in-plane orientation of the film, and Hc decreases as the strain increases. However, if the in-plane orientation of the c-axis increases, the squareness ratio B
r / Bs increases.

Without changing the composition and thickness of the non-magnetic underlayer and the composition and thickness of the magnetic layer of Example 1 described above,
FIG. 6 shows data obtained by measuring the coercive force Hc of the magnetic recording medium having the structure shown in FIG. 1 obtained by changing only the substrate temperature during film formation. It can be seen that a high coercive force is obtained in the substrate temperature range of 100 to 400 ° C. Substrate temperature is 400 ° C
If it exceeds, the interface state between the underlayer and the magnetic layer deteriorates due to alloying, so no experiment was conducted. Although not shown, Hc and the like may be adjusted by heat treatment at 300 ° C. or higher after the magnetic layer is formed.

(Embodiment 2) Using the same RF magnetron sputtering apparatus as in Embodiment 1, a glass disk substrate having a diameter of 65 mm and a thickness of 0.9 mm is first formed to a thickness of 10
0 nm of Cr ₇₀ Mo ₃₀ non-magnetic underlayer 2 and then 40 nm thick Co ₇₅ Pt ₉ Cr ₆ Mo ₁₀ magnetic layer 3
And a carbon protective layer 4 having a thickness of 40 nm was continuously sputtered thereon. The film forming conditions were the same as in Example 1 except that the substrate temperature was 200 ° C. The magnetic recording medium 6 was obtained by taking out from the sputtering device and applying the lubricating layer 5 on the carbon protective layer 4.

When the magnetic characteristics of this magnetic recording medium were measured, the coercive force Hc was 1600 (Oe) and the squareness ratio Br / Bs.
Was 0.85. Compared with the values of Example 1, Hc
However, the squareness ratio is improved. This is because the amount of Mo (element Y) compounded in the magnetic layer 3 is larger than that in the case of Example 1, so that the crystal magnetic anisotropy of the magnetic layer 3 is decreased and the maximum coercive force is obtained. It is considered that the distribution of is shifted in the in-plane direction of the film.

Next, the composition of the magnetic layer 3 is changed to Co ₇₅ Pt ₉ Cr.
The magnetic characteristics of the magnetic recording medium were investigated when the composition of the non-magnetic underlayer 2 was changed by fixing to ₆ Mo _10.
FIG. 7 shows a function of the compounding concentration x of the element X of rX (X = Mo).

Comparing FIG. 7 with FIG. 3, the lattice constant of the magnetic layer 3 increases as the concentration y of the element Y (Y = Mo) compounded in the magnetic layer 3 increases, and therefore the peak of Hc is not given. It can be seen that the compounding concentration x of the element X in the magnetic underlayer 2 is shifted to a higher concentration. In other words, it can be said that the lattice constant of the magnetic layer is larger than that of the underlayer, and the region that gives tensile strain to the magnetic layer is expanded. Hc shows a peak value when the lattice strain becomes the smallest in the vicinity of x = 30 atomic%. The composition region for x before and after this corresponds to the transition region of the c-axis orientation distribution described in Example 1. However, as described above, even if x is selected near the optimum value, the coercive force H is high because the concentration y of the non-magnetic element Y mixed in the magnetic layer 3 is high.
The peak value of c itself is relatively smaller than that in the first embodiment.

Example 3 The composition of the magnetic layer was changed to Co ₇₂ Pt ₁₆
Magnetic recording media were obtained in the same manner as in Examples 1 and 2 except that Cr ₈ Mo ₄ and the composition of the nonmagnetic underlayer were Cr ₈₀ Mo ₂₀ . Table 2 shows the coercive force and squareness of the obtained magnetic recording medium.
As shown in Table 1, the values were 2050 (Oe) and 0.71, respectively, which were excellent values.

(Examples 4 to 10) Non-magnetic underlayer 2 and magnetic layer having different compositions by continuous sputtering and coating of the lubricating layer while heating the substrate in the range of 100 to 400 ° C in the same manner as in Examples 1 and 2. Table 2 shows a magnetic recording medium in which No. 3 is combined and the magnetic characteristics are shown together. In Example 4 listed in Table 2, Nb is blended as the elements X and Y, in Example 5 X and Y are Al, in Example 6 X and Y are Ta, and in Example 7, X is MoTa.
Alloy, Y is Ta, X and Y are Zr in Example 8, X is MoZr alloy in Example 9, Y is Zr, and X and Y are MoZr alloy in Example 10. Further, in order to compare the magnetic characteristics with the respective examples of the present invention, Comparative Examples 4 to 7
The magnetic recording medium of was also prepared and shown in Table 2 together.

As is clear from Table 2, a suitable amount of the nonmagnetic element X having a larger atomic radius than Cr as the main component of the nonmagnetic underlayer and the nonmagnetic element Y having a larger atomic radius than Co as the main component of the magnetic layer is mixed. This makes it possible to adjust the lattice constants of the non-magnetic underlayer and the magnetic layer. As a result, it was shown that the c-axis orientation distribution of the magnetic layer particles can be appropriately controlled, and a magnetic recording medium having a high coercive force and a squareness ratio can be manufactured with a platinum compounding ratio lower than conventional ones.

[0046]

[Table 2]

It has been clarified that it is appropriate to use at least one of Ti, V, Hf and W as X and / or Y in addition to the elements shown in Table 2.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these embodiments and includes the following application examples and modifications. Although a glass disk (amorphous) was used as the non-magnetic substrate in the above-mentioned examples, other than this, crystallized glass, aluminum alloy, ceramics, plastic, carbon, or a suitable inorganic material can be used.

Further, Cr, Mo, W, Ti, Zr, V and N are provided between the non-magnetic substrate and the non-magnetic underlayer made of the above materials.
It is possible to further provide a non-magnetic buffer layer made of a metal such as b, Ta, Mg, or Bi, an alloy thereof, or an oxide such as SiO ₂ or Al ₂ O ₃ . This buffer layer plays a role of promoting grain growth and orientation of the nonmagnetic underlayer.

Further, although carbon is used for the protective layer in the above-mentioned embodiment, other than this, for example, SiO ₂ and Zr are used.
O ₂ , Si ₃ B ₄ , BN, Cr, CrMo alloy or the like can be used. Further, in the above-mentioned embodiment, although pafluoropolyether was used for the lubricating layer, other than this, for example, fatty acid, fatty acid amide, fatty acid ester, fluorocarbon or the like can be used alone or in combination.

[0051]

As described above, according to the present invention,
It is possible to increase the coercive force and squareness of the Co-based alloy magnetic layer laminated on the Cr-based alloy underlayer without increasing the expensive Pt component. As a result, it is possible to provide a magnetic recording medium whose magnetic characteristics are controlled according to the purpose of use.

[Brief description of drawings]

FIG. 1 is a diagram showing a laminated structure of a magnetic recording medium in an example.

FIG. 2 is a diagram showing the dependence of the magnetic characteristic in the comparative example on the compounding concentration x of the element X (= Mo).

FIG. 3 is a diagram showing the dependence of the magnetic characteristics of the comparative example on the compounding concentration x of the element X (= Mo).

4 is a diagram showing a c-axis orientation distribution of magnetic layer particles in the comparative example shown in FIG.

5 is a diagram showing a c-axis orientation distribution of magnetic layer particles in the example shown in FIG.

FIG. 6 is a diagram showing the relationship between the substrate temperature during film formation and the coercive force of an example (Example 1) having the composition shown in the center of FIG.

FIG. 7 is a diagram showing a relationship between an element X (= Mo) concentration x and magnetic properties in another example.

[Explanation of symbols]

 1 Nonmagnetic Substrate 2 Nonmagnetic Underlayer (CrX) 3 Magnetic Layer (CoPtCrY) 4 Protective Layer 5 Lubricating Layer 6 Magnetic Recording Medium

Front page continuation (72) Inventor Junichi Horikawa 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Hoya Co., Ltd.

Claims (8)

[Claims] 1. A nonmagnetic underlayer containing at least (1) Cr and a nonmagnetic element X having a larger atomic radius than Cr and (2) Co and a nonmagnetic element Y having a larger atomic radius than Co on a nonmagnetic substrate. And a magnetic layer containing a magnetic layer, which is laminated in this order, and the c-axis orientation distribution of the magnetic particles forming the magnetic layer is a function of the compounding concentration x of the element X contained in the nonmagnetic underlayer, and x And the x concentration of the element Y so that the magnetic layer film surface has a c-axis orientation transition region that shifts from the vertical orientation type to the in-plane orientation type.
A magnetic recording medium characterized by selecting. 2. The magnetic recording medium according to claim 1, wherein when the y is selected as a predetermined value, the x is selected so that the c-axis orientation distribution falls within the c-axis orientation transition region. 3. The magnetic recording medium according to claim 1, wherein the magnetic layer further contains Pt and Cr. 4. The element X is Mo, Al, Ti, Z.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is at least one selected from the group consisting of r, Nb, Hf, Ta and W. 5. The element Y is Mo, Al, V, Zr,
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is at least one selected from the group consisting of Nb, Hf, Ta and W. 6. The content of Cr in the non-magnetic underlayer is 4
The magnetic recording medium according to claim 1, wherein the content of Co in the magnetic layer is 0 atomic% or more and less than 100 atomic%, and the Co content in the magnetic layer is 60 atomic% or more and 90 atomic% or less. 7. The Pt content in the magnetic layer is 4 atomic%.
The magnetic recording medium according to claim 3, wherein the content is not less than 20 atomic% and not more than 20 atomic%, and the content of Cr is not less than 2 atomic% and not more than 16 atomic%. 8. The magnetic recording medium according to claim 1, wherein the content of the element X is 60 atomic% or less, and the content of the element Y is 20 atomic% or less.