JP2001143251A - Magnetic recording medium and magnetic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which does not impair electromagnetic conversion characteristics, such as a signal-to-noise ratio (S/N) and PW 50, is excellent in thermal stability of a magnetic recording layer and is suitable for a high recording density. SOLUTION: This magnetic recording medium is constituted by successively providing the surface of a substrate with at least a nonmagnetic intermediate layer consisting of a Co alloy and a Co alloy magnetic recording layer. Both of the crystal structures of the intermediate layer and magnetic recording layer described above are hcp structures and the relation between the crystal lattice constant (Li) of the intermediate layer and the crystal lattice constant (Lm) of the magnetic recording layer satisfies [equation 1] |Lm-Li|/Lm<0.019. The magnetic recording medium, which solves the problems described above and satisfies both of the electromagnetic conversion characteristics and the thermal stability of the magnetic recording layer, is thereby obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic recording medium and a magnetic recording apparatus using the same. In particular, the present invention relates to a high recording density medium and a magnetic recording apparatus using the same, which are excellent in coercive force, and excellent in electromagnetic conversion characteristics such as S / N ratio and thermal stability of a magnetic recording layer.

[0002]

2. Description of the Related Art In recent years, the application range of magnetic recording devices such as magnetic disk devices, floppy (registered trademark) disk devices, and magnetic tape devices has been remarkably increased, and their importance has been increased. Magnetic recording media have been adapted to high recording densities. For example, as the recording density of a magnetic recording medium increases, an MR head or a GMR head is used as a recording / reproducing head, and a PRML (Partial R) is used as a digital signal error correction technique.
esponse Maximum Likelihood
d) Since the introduction of technology, the increase in recording density has become even more intense, and has recently been increasing at a rate of 60% per year.

As described above, it is required to further increase the recording density of the magnetic recording medium in the future. For this purpose, a higher coercive force of the magnetic recording layer and a higher signal-to-noise ratio (S) are required.
/ N ratio) and high resolution are required.
Furthermore, in recent years, in order to achieve high recording density, the thickness of the magnetic recording layer has been becoming thinner, and accordingly, the magnetically recorded magnetization has been weakened by thermal disturbance of the fine magnetic particles. This phenomenon has become apparent, and the thermal stability of magnetic recording has become a major technical issue. Above all, S
In many cases, the thermal stability is reduced in order to improve the / N ratio, and it is a development goal to make these two performances compatible. This is because, in general, in a magnetic recording medium having an excellent S / N ratio, the crystal grain size of the magnetic particles constituting the magnetic recording layer is fine, which is effective for reducing noise of the magnetic recording medium. This is because an unstable state is likely to occur from the viewpoint of thermal stability.

Further, in recent magnetic recording media, the S / N ratio, PW5
Factors of the electromagnetic conversion characteristics such as 0 are more emphasized. Here, the PW50 is a half-value width of an isolated waveform observed when recording and reproducing an isolated wave of a recording signal in magnetic recording, and is an amount directly connected to the signal resolution. The smaller the amount, the better the magnetic recording medium.

[0005]

As a technique for achieving a high coercive force and a high S / N ratio, a Co alloy intermediate layer having an hcp structure has been used between a Cr or Cr alloy underlayer and a Co alloy magnetic recording layer. Is known (for example, JP-A-8-329444). According to this method, the effect of significantly increasing the coercive force of the Co alloy magnetic recording layer and improving the electromagnetic conversion characteristics has been reported. However, even if this technique is used as it is, the effect on the thermal stability of the medium as described above has not been sufficient. This is because, as described above, an attempt to improve the S / N ratio causes a reduction in thermal stability of magnetic recording. In the conventional technology of high coercive force and high S / N ratio using a Co alloy intermediate layer, if the thickness of the Co alloy intermediate layer is too thick, the electromagnetic conversion characteristics are significantly reduced.
In order to improve the electromagnetic conversion characteristics such as the ratio and PW50, C
It was necessary to set the thickness of the o alloy intermediate layer as thin as possible. On the other hand, from the viewpoint of securing thermal stability,
It was necessary to make the Co alloy intermediate layer film thickness more than a certain level.

As the electromagnetic conversion characteristics such as the PW50 and the S / N ratio are regarded as very important in the present day, the conventional technology using the Co alloy intermediate layer has excellent thermal stability and electromagnetic conversion characteristics. It was extremely difficult to achieve both.

[0007]

SUMMARY OF THE INVENTION According to the present invention, by controlling the relationship between the crystal structure of a Co alloy intermediate layer and the Co alloy magnetic recording layer formed thereon, the magnetic properties of the Co alloy magnetic recording layer are reduced. The present inventors have found that even if the magnetic recording medium contains particles, the thermal stability of magnetic recording can be improved without impairing the electromagnetic conversion characteristics such as PW50 and S / N ratio of the magnetic recording medium, and the present invention has been completed. That is, the gist of the present invention is that, in a magnetic recording medium in which at least a Co alloy intermediate layer and a Co alloy magnetic recording layer are sequentially provided on a substrate, the crystal structure of the Co alloy intermediate layer and the Co alloy magnetic recording layer is an hcp structure. , The crystal lattice constant of the Co alloy intermediate layer is L
i, when the crystal lattice constant of the Co alloy magnetic recording layer is Lm,

[0008]

| Lm−Li | / Lm <0.019 The present invention resides in a magnetic recording medium and a magnetic recording apparatus using the same.

According to the present invention, it is possible to provide an excellent high-density magnetic recording medium which overcomes the drawbacks of the conventional Co alloy intermediate layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The magnetic recording medium of the present invention has a non-magnetic Co alloy intermediate layer and a Co alloy magnetic recording layer sequentially provided on a substrate. As the substrate in the magnetic recording medium of the present invention, for example, an Al alloy substrate containing Al as a main component such as an Al-Mg alloy, ordinary soda glass, aluminosilicate glass, crystallized glass, silicon, titanium, ceramics, Any material such as a substrate made of various resins can be used. Among them, it is preferable to use an Al alloy substrate or a glass substrate such as crystallized glass.

In the present invention, any Co alloy magnetic material can be used for the Co alloy magnetic recording layer. For example, Co, CoNi, CoSm, CoCrTa, CoNiC
r, CoCrPt, and these Co alloys
i, Cr, Pt, Ta, W, B and other elements and compounds such as SiO ₂ , for example, CoCrPtTa, Co
CrPtB, CoNiPt, CoNiCrPtB, etc.
An alloy magnetic material containing Co as a main component can be used. In the present invention, C containing 1 atomic% or more and less than 30 atomic% of Cr is used.
An o-alloy is particularly preferred. Further, by containing boron (B), the crystal grains in the Co alloy magnetic recording layer are refined, the S / N ratio is good, and the decrease in thermal stability is suppressed. Is preferred. The content of B is preferably 1 to 10 atomic%. The thickness of the Co alloy magnetic recording layer may be appropriately selected depending on the magnetic recording medium to be manufactured. However, in general, if the thickness is too large, the electromagnetic conversion characteristics may be reduced.
Å, preferably 100-300Å, more preferably 1
00 to 250 °.

The Co alloy intermediate layer is usually a non-magnetic layer made of a Co alloy containing Cr. At this time, the content of Cr is, for example, 30 to 60 atomic%, particularly 35 to 50 atomic%.
It is preferred that If the content is less than 30 atomic%, the intermediate layer itself may have magnetism, which adversely affects the recording magnetization of the Co alloy magnetic recording layer, which is not preferable. On the other hand, if the content of Cr exceeds 60 atomic% and is too large, the crystal structure of the Co alloy intermediate layer may be damaged.

The thickness of the Co alloy intermediate layer may be appropriately selected depending on the magnetic recording medium to be manufactured.
00 °, preferably 5-100 °, particularly preferably 10-50 °. The Co alloy intermediate layer and the Co alloy magnetic recording layer are both Co-based alloy layers. However, due to differences in the roles of the respective layers, the types and amounts of elements other than Co to be compounded in each layer are different. Often it is very different. The Co alloy magnetic recording layer is required to have a higher coercive force to achieve higher-density recording and a smaller crystal grain size in the layer, and the types and amounts of elements to be blended for that purpose are required. Is optimized. On the other hand, the Co alloy intermediate layer is preferably non-magnetic in order to minimize the adverse effect on the recording magnetization of the Co alloy magnetic recording layer. In this regard, the Co alloy magnetic recording layer and the Co alloy intermediate layer necessarily have different compositions. However, on the other hand, when producing these layers, the C
Considering that the Co alloy magnetic recording layer is formed on the o alloy intermediate layer, the crystal structure of the Co alloy intermediate layer should be as close as possible to the crystal structure of the Co alloy magnetic recording layer.
Adjusting the crystal structure of the Co alloy intermediate layer provides a good C
Necessary for obtaining an o-alloy magnetic recording layer.

Therefore, in the present invention, it is necessary to control the mutual crystal state of the Co alloy intermediate layer and the Co alloy magnetic recording layer to a specific range. That is, in the present invention, the crystals of the intermediate layer and the magnetic recording layer have an hcp structure, and the relationship between the crystal lattice constant (Li) of the Co alloy intermediate layer and the crystal lattice constant (Lm) of the Co alloy magnetic recording layer is as follows. By satisfying the expression, a Co alloy magnetic recording medium having a good layer structure can be obtained.

[0015]

| Lm−Li | / Lm <0.019 That is, by adjusting the crystal lattice constant of the Co alloy intermediate layer,
When the difference between the crystal lattice constant of the alloy magnetic recording layer and the crystal lattice constant of the Co alloy magnetic recording layer is smaller than the specific value satisfying the above expression, that is, the difference between the crystal lattice constant Lm of the Co alloy magnetic recording layer and the crystal lattice constant Li of the Co alloy intermediate layer. The present invention is achieved by setting | Lm-Li | to be smaller than 1.9% of the crystal lattice constant Lm of the Co alloy magnetic recording layer. This | Lm-Li |
The smaller / Lm is, the better the crystal lattice constant of the Co alloy magnetic recording layer and the crystal lattice constant of the Co alloy intermediate layer are as close as possible. More preferably, | Lm-
Li | / Lm is 0.017 or less, more preferably 0.015 or less, and most preferably 0.005 or less.

As one method of calculating | Lm−Li | / Lm, the plane distance d of the crystal plane of Co is determined by ordinary θ-2θ measurement using an X-ray diffractometer, and the d value of Co is determined.
A method can be used in which the difference between the alloy intermediate layer and the Co alloy magnetic recording layer is divided by the d value of the Co alloy magnetic recording layer.

[0017]

| Lm−Li | / Lm = | dm−di | / dm dm: d value of Co alloy magnetic recording layer di: d value of Co alloy intermediate layer Method of adjusting crystal lattice constant of Co alloy intermediate layer Can usually be achieved by mixing an appropriate element into the Co alloy intermediate layer. A noble metal element is typically used as an element to be blended here. The noble metal element is generally known in general, and specifically, Pt, Ir, Os, Pd, Rh, Ru, Ag, A
u, preferably Pt, Os, Pd, Rh, Ru, especially Pt.

The noble metal element contained in the Co alloy intermediate layer preferably has a metal bonding radius of 1.4 ° or less. As a metal bonding radius of a typical noble metal element, Pt = 1.
385 °, Ir = 1.355 °, Os = 1.35 °, P
d = 1.37 °, Rh = 1.34 °, Ru = 1.34 °
It is. If the content of the noble metal element in the Co alloy intermediate layer is usually 1 atomic% or more, a significant effect can be expected, but if the content is too large, the crystal structure of the Co alloy intermediate layer is rather spoiled. Since it may affect the miniaturization of crystal grains of the magnetic recording layer, the content is preferably 20 atomic% or less, more preferably 15 atomic% or less, and 1 atomic% or less.
More preferably, it is set to 0 atomic% or less.

In the present invention, it is preferable to provide an underlayer made of pure Cr or a Cr alloy layer containing Cr as a main component between the substrate and the Co alloy intermediate layer. This is because the crystal structure of Cr in the underlayer improves epitaxial crystal growth in the Co alloy intermediate layer, refines crystal grains, and controls the orientation of crystal planes. The thickness of the underlayer may be appropriately selected depending on the magnetic recording medium to be manufactured, but is usually 10 to 300 °, particularly preferably 50 to 200 °. In addition to pure Cr, V, Ti, Mo, and Z are added to Cr for the purpose of crystal matching with the Co layer.
Also includes those to which second and third elements such as r, Hf, Ta, W, Ge, Nb, Si, Cu, and B are added, and Cr oxide. Above all, pure Cr, Ti, Mo, W, V, Ta, Si,
Those having Nb, Zr, and Hf are preferable. The optimum content of the second and third elements differs depending on each element, but is generally 1 to 60 atomic%, preferably 5 to 60 atomic%.
-50 at%, more preferably 5-30 at%. The film thickness may be sufficient if the orientation of the Co alloy intermediate layer can be expressed, and is 1 to 500 °, and particularly 3 to 500 °.
300 °, especially 5-100 °, is preferred.

Further, N.sub.2 is provided between the underlayer and the substrate.
It is preferable to provide a seed layer having a B2 crystal structure such as iAl. This is to make the crystal grains of each layer finer,
The film thickness is 50-5000Å, especially 100-2000Å,
Particularly, 300 to 800 ° is preferable. In recent years, glass is often used as a magnetic recording medium substrate from the viewpoint of ensuring impact resistance.
It is preferable to provide a seed layer such as l.

As a method of manufacturing the magnetic disk of the present invention,
A conventionally known method may be appropriately used. Generally, the substrate is generally washed and dried first. In the present invention, it is preferable to perform washing and drying before forming the substrate from the viewpoint of securing the adhesion of each layer. In manufacturing the magnetic recording medium of the present invention, it may be preferable to form a nonmagnetic metal coating layer such as NiP on the substrate surface. As a method for forming the nonmagnetic metal coating layer, a method used for forming a thin film such as an electroless plating method, a sputtering method, a vacuum evaporation method, and a CVD method can be used. In the case of a substrate made of a conductive material, it is possible to use electrolytic plating. The thickness of the non-magnetic metal coating layer may be 500 ° or more. However, in consideration of the productivity of the magnetic recording medium, it is preferable that the angle is 500 to 5000 °. More preferably, it is 500 to 3000 °.

When a glass substrate such as aluminosilicate glass or crystallized glass is used, it is preferable to form the above-mentioned NiAl alloy layer as a coating layer. In this case, the thickness of the coating layer is the same as that of the aforementioned NiAl seed layer. The region where the non-magnetic metal coating layer is formed is desirably the entire region of the substrate surface, but it is also possible to implement only a part, for example, only the region to be textured.

Further, it is preferable that the substrate surface or the substrate surface on which the non-magnetic metal coating layer is formed be textured concentrically in the recording direction, for example, in the case of a disk substrate. In the present invention, concentric texturing is, for example, mechanical texturing using loose abrasive grains and texture tape or texturing using a laser beam, or by using these together, by polishing in the circumferential direction. This refers to a state in which a large number of microgrooves are formed in the circumferential direction of the substrate.

As the type of free abrasive grains for mechanical texturing, diamond abrasive grains, particularly those whose surfaces have been subjected to a graphitization treatment, are most preferred. Alumina abrasive grains are widely used as abrasive grains for mechanical texturing, but diamond abrasive grains have extremely good performance, especially from the viewpoint of orienting the axis of easy magnetization along the texturing grooves. Demonstrate.
Although the cause has not been clarified at present, extremely reproducible results have been obtained.

The surface of the substrate has basically no effect on the effect of the present invention no matter what value the surface roughness (Ra) takes, but the fact that the head flying height is as small as possible is necessary for realizing high density recording. Is effective, and one of the features of these substrates is excellent surface smoothness.
Is preferably 10 ° or less, more preferably 5 ° or less, and particularly preferably 3 ° or less. However, the determination of Ra here is based on the case where measurement is performed using a stylus type surface roughness meter. At this time, the tip of the measuring needle has a radius of about 0.2 μm.

Generally, an arbitrary protective layer is formed on the Co alloy magnetic recording layer, and then a lubricating layer is formed. As the protective layer, a carbonaceous layer of carbon (C), hydrogenated C, nitrogenated C, amorphous C, SiC or the like, or SiO ₂ , Zr ₂ O ₃ , T
A commonly used protective layer material such as iN can be used. Further, the protective layer may be composed of two or more layers. The thickness of the protective layer is 10 to 500 °, particularly 10 to 10 °.
0 °, and it is preferable to set the thickness as thin as possible within a range where durability can be ensured. Examples of the lubricant used in the lubricating layer include a fluorine-based lubricant, a hydrocarbon-based lubricant and a mixture thereof, and are usually 1 to 50 °, preferably 10 to 50 °.
A lubricating layer is formed with a thickness of 30 °. In the magnetic recording medium of the present invention, the Co alloy magnetic recording layer may have a laminated structure of two or more types.

The film forming method for forming each layer of the magnetic recording medium is arbitrary. For example, physical vapor deposition methods such as direct current (magnetron) sputtering, high frequency (magnetron) sputtering, ECR sputtering, and vacuum deposition are used. No. There are no particular restrictions on the conditions at the time of film formation, and the ultimate vacuum degree, substrate heating method and substrate temperature, sputtering gas pressure, bias voltage, and the like may be appropriately determined by the film formation apparatus. For example, in the case of sputtering film formation, the ultimate degree of vacuum is usually 1 × 10 ⁻⁶ Torr or less, the substrate temperature is from room temperature to 400 ° C., the sputtering gas pressure is 1 × 10 ^{−3 to} 20 × 10 ⁻³ Torr, and the bias voltage. Is generally from 0 to -500V. In film formation, it is generally preferable to heat the substrate to about 100 to 350 ° C. in order to promote the segregation of Cr in the Co alloy magnetic recording layer. The substrate heating may be performed before the formation of the underlayer, or when a transparent substrate having a low heat absorption is used, a metal coating film such as NiP is formed in advance to increase the heat absorption. Alternatively, the substrate may be heated after forming a seed layer or the like, and then an underlayer, a Co alloy intermediate layer, or a Co alloy magnetic recording layer may be formed.

A magnetic recording apparatus according to the present invention comprises at least the magnetic recording medium described above, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, and The magnetic recording apparatus has means for performing relative motion by means of a magnetic head and recording / reproducing signal processing means for performing signal input to the magnetic head and reproduction of an output signal from the magnetic head. By configuring the reproducing section of the magnetic head with an MR head, a sufficient signal intensity can be obtained even at a high recording density, and a magnetic recording device having a high recording density can be realized. Also, when the magnetic head is levitated at a height of 0.01 μm or more and less than 0.05 μm, which is lower than that of the conventional magnetic head, the output is improved and the device S / S is increased.
N can be obtained, and a high-capacity, high-reliability magnetic recording device can be provided. Further, by combining a signal processing circuit using the maximum likelihood decoding method, the recording density can be further improved.
Track density 10kTPI or more, linear recording density 200kF
A sufficient S / N can be obtained even when recording / reproducing at a recording density of CI or more and 2 Gbits / square inch or more.

Further, the reproducing portion of the magnetic head is disposed between a plurality of conductive magnetic layers which generate a large resistance change due to a relative change in their magnetization directions due to an external magnetic field, and the conductive magnetic layers. G consisting of a conductive non-magnetic layer
MR head or G using spin valve effect
By using an MR head, the signal strength can be further increased, and 3 gigabits or more per square inch can be achieved.
A highly reliable magnetic recording device having a linear recording density of 40 kFCI or more can be realized.

In particular, the magnetic recording medium of the present invention has a track density of 34 kTPI or more and a linear recording density of 415 kFCI or more.
This is effective when recording is performed at a recording density of 15 gigabits or more per square inch. As the recording density increases, the magnetization region corresponding to one bit decreases, and the thermal stability of the magnetization tends to deteriorate. Therefore, as the recording density increases, the thermal stability of the recording magnetization deteriorates, and the recording signal tends to attenuate. The present invention is effective in improving the thermal stability of this recording magnetization, and this effect is higher at higher recording densities, for example, at the above-mentioned 15 gigabits per square inch or more, as compared with those not using the present invention. It becomes remarkable in such a case.

[0031]

The present invention will be described more specifically with reference to the following examples. However, unless the present invention exceeds the gist,
The present invention is not limited to the following embodiments. (Examples 1 to 4, Comparative Example 1, Reference Examples 1 and 2) A vacuum chamber in which a glass substrate for HD is set is set to 1.0 × in advance.
The chamber was evacuated to 10 ^-5 Pa or less. The glass substrate used here was made of lithium-reinforced crystallized glass and had a Ra of about 5
Å, outer diameter 65 mm, inner diameter 20 mm. Further, the substrate is heated to about 250 ° C., and a Ni ₅₀ Al ₅₀ layer, Cr ₉₄ Mo ₆
Layer, CoCrPt layer, Co ₆₆ Cr ₂₀ B ₆ Pt ₈ layer, carbon protective layer, fluorine-based lubricant (Fomblin Z-Do)
12000: manufactured by Audimont Co.). All layers other than the fluorine-based lubricant layer were formed by DC sputtering, and no bias voltage was applied to the substrate. The partial pressure of argon gas during film formation was set to about 7.0 × 10 ⁻¹ Pa.

The layer structure is C / CoCrBPt / Co from above.
CrPt / CrMo / NiAl / substrate was used. Among them, the composition of the CoCrPt layer is Co ₅₆ Cr ₄₂ Pt ₂ atomic%.
Was set. The thickness of each layer is NiAl layer 600
And Å, Cr ₉₄ Mo ₆ layer _{100Å, Co 66 Cr 20 B 6} Pt 8 layer 250 Å, and a carbon protective layer 50 Å, the thickness of the CoCrPt layer was changed as 0,3,5,10,20A. Among them, the CoCrPt intermediate layer having a thickness of 0 ° was determined as Comparative Example 1, and similarly, the CoCrPt intermediate layer having a thickness of 3, 5, 10, and 2 was used.
Those of 0 ° were referred to as Examples 1, 2, 3, and 4, respectively. The output attenuation of the magnetic recording medium thus manufactured was examined. Generally, a medium having a higher S / N ratio (SNR) tends to be thermally unstable, and it is a feature of the present invention to achieve both a high S / N ratio and suppression of output attenuation.

As a reference example, the S / N ratio and output attenuation of a magnetic disk in which the same NiAl, CrMo, CoCrTaPt-based magnetic film material and carbon protective layer were laminated in this order on the crystallized glass substrate were used. It was shown to. Similarly, NiAl, CrMo, CoC on a crystallized glass substrate
Reference Example 2 The S / N ratio and output attenuation of a magnetic disk medium in which an rBPt-based magnetic material and a carbon protective layer were laminated in this order were measured.
Shown in It can be seen that the output attenuation increases as the S / N ratio increases. Table 1 shows the measurement results.

[0034]

[Table 1]

FIG. 1 is a graph of this.
By inserting a Pt-containing Co alloy intermediate layer, S / N
It can be clearly seen that the output attenuation decreases with little decrease in the ratio. As shown in the reference example and the comparative example, the relationship between SNR and output attenuation on a straight line is deviated, and only the output attenuation decreases with an increase in the thickness of the CoCrPt intermediate layer while the SNR remains almost constant. This is clearly recognized. (Examples 5 to 8 and Comparative Examples 2 to 5) Further, in the same manner, those using Co ₆₃ Cr ₃₇ for the Co alloy intermediate layer and those using the Pt-containing Co alloy intermediate layer of the present invention were produced.
The thickness of the intermediate layer is set to 20, 50, 100, 200, respectively.
Å was changed. Samples using the Co ₆₃ Cr ₃₇ intermediate layer not containing Pt were compared with Comparative Examples 2 to 5, and Co ₅₆ Cr containing Pt.
Samples using ₄₂ Pt ₂ for the intermediate layer are referred to as Examples 5 to 8.
At this time, how the PW50 value of each magnetic disk changes was measured and summarized in Table 2. As described above, the PW50 value is a very important parameter for increasing the linear recording density of a magnetic disk, and the smaller the value, the better the characteristics.

Comparative Example 4 (when the thickness of the intermediate layer is 100 °)
, After forming a Co alloy intermediate layer,
Using an X-ray diffractometer of Company s, the d value of the Co (100) plane distance d of the Co alloy intermediate layer was obtained by ordinary θ-2θ measurement.
After the formation of the Co alloy magnetic layer, the Co
The Co (100) plane spacing d value of the alloy magnetic layer was determined. Co
(100) face distance d value and | Lm obtained based on this value
Table 3 shows the values of −Li | / Lm.

[0037]

[Table 2]

FIG. 2 shows a graph of these results. In the conventional Pt-free Co alloy intermediate layer, the PW50 rapidly deteriorates as the film thickness increases, whereas in the case of the Pt-containing Co alloy intermediate layer, almost no deterioration is observed. . This is an extremely advantageous feature in obtaining high recording and reproducing characteristics while securing the above-mentioned thermal stability.

Example 9 The composition of the Co alloy intermediate layer was Co
_A magnetic disk was manufactured under the same conditions as in Comparative Example 4, except that ₅₄ Cr ₃₇ Pt ₉ was used. Using the same method as in Comparative Example 4, Co
The Co (100) plane distance d value of the alloy intermediate layer and the Co alloy magnetic layer was determined. Table 3 shows the Co (100) plane spacing d value and the value of | Lm−Li | / Lm obtained based on this value.

[0040]

[Table 3]

Example 7 (2 atomic% of P in the Co alloy intermediate layer)
t) shows a good PW50, and | Lm
-Li | / Lm is estimated to be about 0.016. Comparative Example 4
(Lt-L of Co alloy intermediate layer not containing Pt)
i | / Lm is 0.020 as a result of the measurement, and the recording characteristic P
W50 is inferior. In the case of Example 9 in which Pt was contained in the Co alloy intermediate layer at 9%, | Lm−Li | / Lm was 0.002 as a result of measurement, and the crystal lattice constant of the Co alloy intermediate layer was C
It can be seen that it is very close to the crystal lattice constant of the o-alloy magnetic recording layer, and it is expected that a good recording characteristic PW50 will be exhibited.

[0042]

As described above, according to the present invention, it is possible to provide a magnetic recording medium that has a small amount of electromagnetic conversion characteristics and excellent thermal stability.

[Brief description of the drawings]

FIG. 1 shows output attenuation and S / N ratio in magnetic recording media of the present invention, a comparative example, and a reference example.

FIG. 2 shows a PW50 value and a Pt-containing Co-containing intermediate layer thickness in magnetic recording media of the present invention and a comparative example.

Claims (17)

[Claims] 1. A magnetic recording medium comprising a substrate and a non-magnetic intermediate layer made of at least a Co alloy and a Co alloy magnetic recording layer sequentially provided on a substrate, wherein both the intermediate layer and the magnetic recording layer have hcp crystal structures. A crystal lattice constant (Li) of the intermediate layer and a crystal lattice constant (Lm) of the magnetic recording layer.
And Lm-Li | / Lm <0.019, which satisfies the following expression: | Lm−Li | / Lm <0.019. 2. The magnetic recording medium according to claim 1, wherein the Co alloy intermediate layer contains a noble metal element. 3. The magnetic recording medium according to claim 2, wherein an atomic radius of the noble metal element is 1.4 ° or less. 4. The noble metal element is at least one element selected from Pt, Os, Pd, Rh and Ru.
Or the magnetic recording medium according to 3. 5. The magnetic recording medium according to claim 2, wherein the noble metal element is Pt. 6. The precious metal element content of the Co alloy intermediate layer is 1
The magnetic recording medium according to any one of claims 2 to 5, wherein the content of the magnetic recording medium is from 20 to 20 atomic%. 7. The magnetic recording medium according to claim 1, wherein the Co alloy intermediate layer is a nonmagnetic layer made of a Co alloy containing Cr. 8. The magnetic recording medium according to claim 1, wherein the Co alloy intermediate layer is a non-magnetic layer made of a CoCrPt alloy. 9. A Co alloy intermediate layer having a Cr content of 30.
9. The magnetic recording medium according to claim 7, wherein the content of the magnetic recording medium is about 60 to 60 atomic%. 10. The magnetic recording medium according to claim 1, wherein the thickness of the intermediate layer is 1 to 300 °. 11. The magnetic recording layer according to claim 1, wherein said Co alloy magnetic recording layer is at least 1 atomic%.
2. A Co alloy containing less than 0 atomic% of Cr.
11. The magnetic recording medium according to any one of claims 10 to 10. 12. The magnetic recording medium according to claim 1, wherein the Co alloy magnetic recording layer contains boron. 13. The magnetic recording medium according to claim 1, wherein the thickness of the Co alloy magnetic recording layer is 400 ° or less. 14. The magnetic recording medium according to claim 1, further comprising an underlayer made of Cr or a Cr alloy between the substrate and the Co alloy intermediate layer. 15. The magnetic recording medium according to claim 14, further comprising a seed layer between the substrate and the underlayer. 16. The magnetic recording medium according to claim 15, wherein the seed layer is made of a NiAl alloy. 17. A magnetic recording medium, a drive unit for driving at least the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, and means for moving the magnetic head relative to the magnetic recording medium; 17. A magnetic recording apparatus having a recording / reproducing signal processing means for inputting a recording signal to a magnetic head and outputting a reproduction signal from the magnetic head, wherein the magnetic recording medium is the magnetic recording medium according to claim 1. apparatus.