JP2000113445A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having higher coercive force and improved thermal fluctuation resistance so as to be suitable for high density magnetic recording. SOLUTION: Ground surface layers 12 and 13 to be disposed at the lower layer of magnetic films of a Co alloy system are formed as multiple layers and more particularly an alloy material of Co-Rux-cry (5 at.% <=x<=65 at.%, 35 at.%>=y>=0 at.%) having a hexagonal closepacked structure is used as the upper layer ground surface layer 13 to be formed in contact with the magnetic film 14. As a result, the coercive force of the magnetic recording medium is made higher and the thermal fluctuation resistance thereof is made better. The magnetic recording medium having the characteristics necessary for high density magnetic recording above 10 Gb/in2 may be embodied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium having a magnetic film suitable for high-density magnetic recording.

[0002]

2. Description of the Related Art Magnetic disk drives currently in practical use employ an in-plane magnetic recording system. In the in-plane magnetic recording system, it is a technical problem to form in-plane magnetic domains parallel to the substrate at high density on an in-plane magnetic recording medium which is easily magnetized in a direction parallel to the disk substrate surface. In order to increase the recording density of this longitudinal magnetic recording medium, the coercive force must be improved and the magnetic film thickness must be reduced. However, if the magnetic film thickness is too small, the problem that the recording magnetization decreases or disappears due to the influence of heat is encountered. The magnetic film thickness at which the influence of the thermal fluctuation of magnetization becomes remarkable is set to 20 nm or less in a Co alloy system. When recording media using a Co alloy-based magnetic film have been increased in density, if the trend so far is extended, in order to achieve a recording density of 10 Gb / in ² or more, the thickness of the magnetic film must be 20 nm or less. It is a prospect that must be taken. 10G using Co alloy magnetic film
In order to realize a recording density of b / in ² or more, it is necessary to further increase the coercive force and to improve the crystallinity of crystal grains constituting the magnetic film. More preferably, it is necessary to refine the crystal grain size in accordance with the improvement of the recording density and narrow the crystal grain size distribution.

In order to improve the coercive force of a magnetic film made of a Co alloy, a material having a body-centered cubic (bcc) structure such as Cr or a Cr alloy or a B2 structure such as NiAl is provided between the magnetic film and the substrate. A method of providing an underlayer is adopted (David E. Laughlin, YC Feng, David N. Lambet
h, Li-Lien Lee, Li Tang, “Design and crystallograp
hy of multilayered media "in Journal of Magnetism
and Magnetic Materials, Vol. 155, pp.146-150, 199
6). It is known that it is effective to adjust the condition of the lattice constant of the Co alloy to be epitaxially grown and the base of the bcc in order to improve the coercive force of the magnetic film (N.
Inaba, A. Nakamura, T. Yamamoto, Y, Hosoe, M. Fut
amoto, “Magnetic and crystallographic properties o
f CoCrPt thin films formed on Cr-Ti single crystal
line underlayers "in Journal of Applied Physics, Vo
l.79, No.8, pp.5354-5356, 1996). In order to further improve the crystallinity of the Co alloy magnetic film, a new underlayer made of a nonmagnetic hexagonal dense (hcp) material having the same crystal structure as the Co alloy magnetic film is added between the underlayer and the magnetic film. Is effective (JP-A-4-321919).
A 35 at% Cr underlayer or the like is used as an underlayer for a Co—Cr—Pt magnetic film (M. Futamoto, Y. Honda, Y. H.
irayama, K. Itoh, H. Ide, Y. Maruyama, “High Dens
ity Magnetic Recording on Highly Oriented CoCr-All
oy Perpendicular Rigid Disk Media "in IEEE Transac
tions on Magnetics, Vol.32, No.5, pp.3789-3794, 19
96).

[0004]

In order to enable high-density magnetic recording of 10 Gb / in ² or more, it is necessary for a longitudinal magnetic recording medium to have a high coercive force and an improvement in thermal fluctuation characteristics. An object of the present invention is to facilitate realization of high-density magnetic recording of 10 Gb / in ² or more with a magnetic recording medium using a magnetic film containing a Co alloy, particularly Pt.

[0005]

As a result of a detailed examination of the heat fluctuation characteristics of the conventional in-plane magnetic recording medium, a region having low magnetic anisotropy energy and poor crystallinity was formed in a part of the magnetic film. It was found that the recording magnetization deteriorated from the portion. It was found that the presence of a region having poor crystallinity also reduced the coercive force of the medium. In order to further improve the heat fluctuation characteristics, it is effective to reduce the particle size distribution of the crystal grains constituting the magnetic film. The present invention achieves the above object by forming a multi-layered underlayer provided between a magnetic film and a substrate, and finally controlling the orientation, grain size, and crystallinity of crystal grains constituting the magnetic film. is there.

[0006] The magnetic film material of the medium most commonly used and studied in longitudinal magnetic recording is a Co alloy material having a hexagonal close-packed (hcp) structure. In a Co alloy-based in-plane magnetic recording medium, a region having low crystallinity exists in the initial growth region of the film. The crystallinity of this portion is strongly affected by the underlayer. The present invention solves the problem of crystallinity of a magnetic film by employing a structure of an underlayer consisting of at least two layers, and in particular, by using a material selected for an upper underlayer on the side in contact with the magnetic film. .

A description will be given with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of a medium structure for realizing the present invention. On a non-magnetic substrate 11, a lower underlayer 12 having a B2 structure for controlling crystal orientation and grain size is formed. Ni
Al, FeAl, FeV, CuZn, CoAl or CuPd ordered phase is a material having a B2 structure. When a film made of such a material is formed on a substrate, an alignment film having a (100) plane parallel to the substrate is easily grown. There is nature. further,
The distribution of crystal grains constituting a film made of a material having such a B2 structure tends to be smaller than a case where a film made of a single metal such as Cr, V, or Nb is formed. B2
When a material having a structure is formed on a nonmagnetic substrate by a sputtering method or the like, the (112) orientation film grows preferentially. When a Co alloy film having an hcp structure is formed thereon, the (10-10) plane grows in parallel with the substrate by epitaxial growth. In the present invention, on the lower base layer 12, to form a Co-Ru _x -Cr _y nonmagnetic or weak magnetic upper underlayer 13 made of an alloy material having a hcp structure. Where 5a
It is assumed that t% ≦ x ≦ 65 at% and 35 at% ≧ y ≧ 0 at%.

[0008] Co and Ru are metallic materials having a hcp structure and forming a solid solution with each other. When Ru is dissolved in Co at a concentration of 34 at% or more, it changes to non-magnetic. Since Ru has a larger metal atomic radius of 1.32 angstroms than the metal atomic radius of Co of 1.26 angstroms, the average metal atomic radius increases as the amount of Ru added in Co increases.
The Co alloy magnetic film used for the recording layer of the magnetic recording medium is C
A material obtained by adding elements such as Cr, Ta, Pt, Nb, B, and Y to o is used, and the average metal atomic radius of the alloy magnetic film is generally larger than that of pure Co. The material used for the upper underlayer must have the same hcp structure as the Co alloy, and have a small difference in average metal atom radius and be non-magnetic or weakly magnetic in order to adjust the epitaxial growth conditions. Co-Cr-T used for recording layer
a, Co-Cr-Pt, Co-Cr-Pt-Ta, Co
-Cr-Pt-Ta-Nb, Co-Cr-Pt-Ta-
The average atomic radius of B and the like was found to be in the range of 1.265 to 1.290 angstroms according to experiments performed by the present inventors. In particular, in a medium in which Pt is added to Co as an alloy element, the metal atomic radius of Pt is 1.38.
Since the thickness is as large as Å, the average metal atom radius increases almost in proportion to the amount of Pt added. Co-Ru 2
In order to obtain an atomic radius in this range in the original system, R
u had to be added at 5-65 at%.

In a region where the addition amount of Ru is as small as 5 to 34 at%, the alloy shows magnetism, so that Cr is added to make it non-magnetic or weakly magnetic. Since the metal atomic radius of Cr is 1.28 angstroms and is close to that of Co,
Even if Cr is added to Co, the average metal atomic radius hardly changes. When 25 at% or more of Cr is added to Co, the Co—Cr alloy becomes non-magnetic. When the addition amount of Ru to Co is in the range of 5 to 34 at%, Cr is reduced to 35 at the maximum.
By adding at%, it is necessary to demagnetize or weaken the Co—Ru—Cr material. The range of the weak magnetism that can be accepted as the underlayer is that the saturation magnetization (Ms) is 30 em.
u / cc or less, when the Co-Ru ₅ -Cr _y alloy,
y> 19 at%. It is effective to adjust the amount of Cr added in accordance with the amount of Ru added to Co. In the range where the Ru addition amount exceeds 30 at%, the Cr addition amount is 0a.
Since Ms <30 emu / cc even if t%, Co
The range of the addition amount of Cr in -ru _x -Cr _y,
34 at% ≧ y ≧ 0 at%. However, Co-Ru _x
Align the grain size of the crystal grains constituting the -cr _y alloy underlayer and clarifies the grain boundaries, Cr addition amount in order to function improvement as the underlying layer, that is y ≧ 5at% desirable. The addition of Cr selectively segregates Cr at the grain boundaries in the alloy, thereby producing the above-described desirable effects.

[0010] As upper base layer for recording magnetic film of Co alloy, by providing the above-mentioned Co-Ru _x -Cr _y alloy, can improve the crystal grains of the crystalline constituting the recording magnetic film and the coercive force Can be increased. As the difference between the average of the metal atomic radius of the magnetic film and the upper base layer is 5% or less, by promoting the adjustment of the amount of Ru in the Co-Ru _x -Cr _y, it is amplified these effects it can. C case where the Co-Ru _x -Cr _y alloy as an upper base layer, particularly effective magnetic film materials for records containing Pt
o alloy, in particular, as a Pt addition amount range of 5 at% to
Materials in the range of 30 at% are preferred. A Co alloy magnetic film containing a Pt content in this composition range is suitable for application to a magnetic recording medium having a high coercive force having high magnetic anisotropy energy and good heat fluctuation resistance.

[0011] The thickness of the Co-Ru _x -Cr _y alloy film 0.5
nm or more and 100 nm or less, a particularly desirable range is 1 nm or more and 50 nm or less. The crystal strain Co-Ru _x -Cr _y alloy film by the influence of the underlying base layer remains at 0.5nm or less, and because the surface undulations generated in association with the film thickness becomes more than 100nm becomes thicker increases, It becomes difficult to ensure the smoothness of the medium surface required for a high-density magnetic recording medium.

FIG. 2 is a schematic sectional view showing another example of the magnetic recording medium of the present invention. The lower underlayer 22 formed on the nonmagnetic substrate 21 is made of a bcc structure material such as Cr, V or an alloy thereof, and the upper underlayer 23 is formed of hcp.
Co-Ru _x -Cr _y having the structure (5at% ≦ x ≦ 65a
A similar effect is obtained by using an alloy material of (t%, 35 at% ≧ y ≧ 0 at%). Further, as another application form of the present invention, a material layer having a B2 structure, a C layer having an hcp structure are provided on a bcc structure material layer as a lower underlayer.
_{o-Ru x -Cr y (5at} % ≦ x ≦ 65at%, 35a
t% ≧ y ≧ 0 at%) is provided, and C
A recording magnetic film layer made of an o-alloy may be provided. Alternatively, a material layer having a B2 structure as a lower base layer, and a bcc layer of Cr, V, an alloy thereof, or the like as an intermediate base layer thereon.
Co—having an hcp structure as a structural material layer and an upper underlayer
Ru _x -Cr _y (5 at% ≦ x ≦ 65 at%, 35 at%
.Gtoreq.y.gtoreq.0 at%), and a recording magnetic film layer made of a Co alloy may be provided thereon.

FIG. 3 shows a cross-section of a medium structure for realizing a magnetic recording medium in which the grain size distribution of the crystal constituting the recording magnetic film is controlled in addition to the above effects. A lower underlayer 32 having a NaCl type crystal structure such as MgO or LiF is formed on a non-magnetic substrate 31. For a material film such as MgO or LiF, a (100) oriented film is easily obtained, and the distribution of crystal grain sizes is narrow and the grain sizes are easy to be uniform. Film formation conditions (substrate temperature,
10 Gb / in by adjusting the deposition rate
Desirable crystal grain size of 10 for realizing recording density of ² or more
An underlayer of about nm can be easily formed. Intermediate underlayer 33
Is made of a material having a B2 structure, and the upper underlayer 34 is made of hc
with p structure _{Co-Ru x -Cr y (5at} % ≦ x ≦ 65
at%, 35 at% ≧ y ≧ 0 at%). On this, a magnetic film 35 for a recording layer made of a Co alloy having an hcp structure is formed.

FIG. 4 shows a nonmagnetic substrate 41 and MgO, LiF
In this case, the adhesive strength of the lower underlayer 43 having the NaCl type crystal structure is enhanced, or the material layer having the NaCl structure becomes (10
0) In order to prepare conditions for easily forming an alignment film, Si,
Cr, Ti, Nb, Zr, Hf, Ta, SiO x, Zr
This shows an example in which an adhesion reinforcing layer 42 made of O ₂ , SiN or an alloy containing these as a main component is provided. As the adhesion reinforcing layer, in addition to the above materials, for example, Si-30a
t% Cr, Si-15at% Ge, Nb-30at% Z
An alloy or a mixture of r, SiO ₂ + ZrO ₂ , SiO ₂ + MgO and the like may be used.

[0015]

Embodiments of the present invention will be described below. [Example 1] Using a glass substrate having a diameter of 2.5 inches,
An in-plane magnetic recording medium having a cross-sectional structure shown in FIG. 1 was manufactured by a DC magnetron sputtering method. On a substrate 11, a lower underlayer 12, an upper underlayer 13, a recording magnetic film 1
4 and the protective film 15 were formed in this order. NiAl target for lower base, for upper base Co-Ru _x -
Cr _y target, the recording magnetic film Co-21 at% C
An r-15 at% Pt target and a carbon target for a protective film were used. Co-Ru _x -Cr _y is the target composition using a mixed target of placing the Ru or Cr pellets on Co-50at% Ru alloy target, 3at% ≦ x ≦ 70at% is deposited composition, 40at% ≧ y ≧ 0
At% was adjusted.

The Ar gas pressure for sputtering is 3 mTorr,
Under the conditions of a sputter power of 10 W / cm ² and a substrate temperature of 250 ° C., a NiAl film was formed to a thickness of 15 nm, an upper underlayer was formed to a thickness of 5 nm, a magnetic film was formed to a thickness of 16 nm, and a carbon film was formed to a thickness of 8 nm.
A perfluoropolyether-based film was applied as a lubricating film. The following results were obtained as the composition of the upper underlayer of the prepared sample. Co-10at% Ru, Co-20at% R
u, Co-30at% Ru, Co-35at% Ru, C
o-40at% Ru, Co-50at% Ru, Co-6
0 at% Ru, Co-65 at% Ru, Co-75 at
% Ru, Co-85 at% Ru, Co-10 at% Ru
-5at% Cr, Co-20at% Ru-5at% C
r, Co-30at% Ru-5at% Cr, Co-50
at% Ru-5 at% Cr, Co-65 at% Ru-5
at% Cr, Co-75at% Ru-5at% Cr, C
o-30at% Ru-10at% Cr, Co-60at
% Ru-10at% Cr, Co-10at% Ru-20
at% Cr, Co-20at% Ru-20at% Cr,
Co-40at% Ru-20at% Cr, Co-10a
t% Ru-30at% Cr, Co-25at% Ru-3
0 at% Cr, Co-40 at% Ru-30 at% C
r, Co-5 at% Ru-35 at% Cr, Co-25
at% Ru-35 at% Cr, Co-5 at% Ru-4
0 at% Cr, Co-30 at% Ru-30 at% C
r.

As comparative samples, a sample in which a Co-21 at% Cr-15 at% Pt magnetic film was formed directly on a NiAl underlayer (Comparative Example 1), and a non-Co-35 at% Cr film on a NiAl underlayer. A sample (Comparative Example 2) in which a magnetic upper layer was provided to form a Co-21 at% Cr-15 at% Pt magnetic film was prepared. In these samples, the average metal atom radius of the upper underlayer and the recording magnetic film was measured by an X-ray diffraction method, and the coercive force was measured by a vibrating magnetometer (VSM). The evaluation of the recording / reproducing characteristics was performed using a recording / reproducing separated magnetic head. The gap length of the recording head is 0.2 μm, the shield interval of the spin valve head for reproduction is 0.2 μm, and the spacing at the time of measurement is 0.04.
μm. Measurement of the change over time of the recording signal is 350 kF
It was evaluated as the ratio of the reproduced output ( _{St = 0} ) immediately after recording of the CI magnetic recording signal and the reproduced output ( _{St = 100} ) after 100 hours.

FIG. 5 shows the measured values of the average metal atomic radius of the Co-Ru-Cr alloy system of the upper underlayer and Co-2
The value of the average metal atom radius of the 1 at% Cr-15 at% Pt magnetic film is shown. The metal atomic radius of the Co-Ru-Cr alloy system increased depending on the Ru concentration. The Ru concentration that is almost equal to the metal atomic radius of the magnetic film is 20-40 at% R
u range.

FIG. 6 shows the relationship between the Ru concentration of the Co-Ru-Cr alloy and the coercivity of the medium. The coercive force considered to be necessary for realizing a recording density of 10 Gb / in ² or more is 2.5 kOe
The above Ru composition range is 5 to 65 at%, and even in this range, it is found that the coercive force becomes 2.5 kOe or less when the Cr concentration exceeds 35 at%.
When the composition range of Ru is set to 10 to 30 at%, 3.
A coercive force of 0 kOe or more is obtained. On the other hand, the coercive force of each of the samples of Comparative Examples 1 and 2 was 2.5 kOe or less, confirming that the present invention was effective for obtaining a high coercive force.

FIG. 7 shows the 10 k of the recording signal of 350 kFCI.
It is a figure which shows the output ratio after 0 hour. Range 0.9 or more ratios are obtained, 5at% ≦ x ≦ 65at% in Co-Ru _x -Cr _y alloy, to be 35at% ≧ y ≧ 0 was confirmed. In addition, 10at% ≦ x ≦ 30at
%, A ratio of 0.95 or more can be obtained. Also, by comparing the results of FIGS. 6 and 7,
In the medium using the same recording magnetic film, it was found that a medium having a high coercive force also had good stability of a recording signal.
It was found that the magnetic recording medium according to the present invention had an improved reduction ratio of the recording signal as compared with any of Comparative Examples 1 and 2.

Example 2 In Example 1, a material having a bcc structure was used as the lower underlayer, and Co-17 at% Cr-20 at% Pt-3 was used as the magnetic film for recording.
A magnetic recording medium having a cross-sectional structure shown in FIG. 2 was prepared by using the same film thickness, composition, and forming process conditions except that at% Ta was used. Here, as materials having a bcc structure, Cr, Cr-50 at% V, Cr-5 at% Ti,
Cr-10 at% Nb and Cr-15 at% Mo were used.

As a comparative sample, a sample without the upper underlayer was prepared. As a result of measuring the coercive force of the medium, the results shown in Table 1 were obtained. It can be seen that the magnetic recording medium having the underlayer proposed in the present invention has a large coercive force. N
When the underlayer deviates from the proposal of the present invention as in the samples of Examples 9, 10, 16, 27 and 29, the contribution to the improvement of the performance of the magnetic recording medium is not so large.

[0023]

[Table 1]

[Embodiment 3] In Embodiment 1, FeAl, FeV, CuZn,
A magnetic recording medium was prepared under the same conditions except that CoAl and CuPd materials were used. As a result of examining the effect of improving the medium coercive force and the stability of the recording magnetic signal over time,
Similar results to Example 1 were obtained, confirming the effectiveness of the present invention.

[Embodiment 4] A material having a NaCl structure is used as a lower underlayer, a regular alloy layer having a B2 structure is used as an intermediate underlayer, a Co-Ru-Cr alloy film is used as an upper underlayer, and recording is performed. Co-18at% Cr as magnetic film
Using -15 at% Pt-4 at% Nb, a magnetic recording medium having a sectional structure shown in FIG. 3 was prepared. MgO and LiF were used as materials having a NaCl structure. Except that the high frequency sputtering method was adopted as the method of forming the lower underlayer,
The same film thickness, composition, and forming process conditions as in Example 1 were used.

As a comparative sample, a sample in which the lower underlayer having the NaCl structure was not introduced, and C was used as the upper underlayer.
A sample (comparative example) using o-30 at% Ru-5 at% Cr was prepared. As a result of measuring the coercive force of the medium, the results shown in Table 2 were obtained. It can be seen that the magnetic recording medium of the present invention has a larger coercive force than the comparative example. Note that N
When the composition range of the upper underlayer deviates from the range proposed in the present invention as in o. 9, 10, 16, and 27, the contribution to the performance improvement of the magnetic recording medium is not so large.

[0027]

[Table 2]

Further, MgO of a material having a NaCl structure is provided on the lower underlayer, and Co-3 is formed thereon as an upper underlayer.
The distribution of crystal grains constituting the recording magnetic film of the sample provided with 0 at% Ru-5 at% Cr and the comparative example was measured, and the results shown in FIG. 8 were obtained. It was found that the sample in which the lower underlayer made of MgO was formed had a narrower crystal grain distribution and a uniform particle size, and had more desirable characteristics as a high-density magnetic recording medium.

Example 5 Using a 2.5 inch diameter silicon substrate, a magnetic recording medium having a cross-sectional structure shown in FIG. 4 was produced by a high frequency sputtering method and a DC magnetron sputtering method. On a substrate 41, Si, Cr, Ti, Nb, Zr, Ta, Hf, SiO
_{2, ZrO 2, SiN, Si} -25at% Cr, Si-5
at% Ti, SiO ₂ + ZrO ₂ , MgO as the lower underlying layer 43, Cr as the intermediate underlying layer 44, Co-20 at% Ru-15 at% Cr as the upper underlying layer 45,
Co-20 at% Cr-13a as the recording magnetic film 46
In this order, t% Pt-2at% Nb and carbon as the protective film 47 were formed. Here, the non-conductive material Si
A high frequency sputtering method was used for forming a film of O ₂ , SiN, SiO ₂ + ZrO ₂ , and a DC magnetron sputtering method was used for forming other films. Ar gas pressure for sputtering is 3mTo
rr, sputter power 10 W / cm ² , substrate temperature 28
Under the condition of 0 ° C., the adhesion enhancement layer is 2 nm, and the lower underlayer is 5 n
m, an intermediate underlayer of 10 nm, an upper underlayer of 3 nm, a magnetic film of 15 nm, and a protective film of 7 nm to form a magnetic recording medium. As a comparative sample, a medium having the same structure except that no adhesive strength lower layer was provided. The coercive force of the medium was measured with a VSM, and the adhesive strength was measured with an Al ₂ O ₃ —TiC spherical slider. When the number of times of sliding was 105 times and no peeling of the medium was observed, it was evaluated as ○, and when it was less than that, it was evaluated as ×. Table 3 shows the measured results.

[0030]

[Table 3]

[0031]

According to the present invention, the high coercive force of the magnetic recording medium and the stability of the thermal fluctuation can be ensured, so that high-density magnetic recording of 10 Gb / in ² or more can be achieved, and the size of the apparatus can be reduced. It is easy to increase the capacity and increase the capacity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a magnetic recording medium according to the present invention.

FIG. 2 is a schematic sectional view of another example of the magnetic recording medium according to the present invention.

FIG. 3 is a schematic sectional view of another example of the magnetic recording medium according to the present invention.

FIG. 4 is a schematic sectional view of another example of the magnetic recording medium according to the present invention.

FIG. 5 is a diagram showing the relationship between the composition of an upper underlayer and the average metal atom radius.

FIG. 6 is a diagram showing the relationship between the composition of the upper underlayer and the coercive force of the medium.

FIG. 7 is a diagram showing a relationship between a composition of an upper underlayer and an output ratio of a magnetic recording signal.

FIG. 8 is a diagram showing a distribution of diameters of crystal grains of a medium.

[Explanation of symbols]

11 nonmagnetic substrate, 12 lower underlayer, 13 upper underlayer, 14 magnetic film, 15 protective film, 21 nonmagnetic substrate,
22 lower underlayer, 23 upper layer, 24 lower magnetic film, 25 protective film, 31 nonmagnetic substrate, 32 lower layer, 33 intermediate layer, 34 upper layer, 35 magnetic layer Film: 36: Protective film, 41: Non-magnetic substrate, 42: Adhesion reinforcing layer, 43: Lower underlayer, 44: Intermediate underlayer, 45: Upper underlayer, 46: Magnetic film, 47: Protective film

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiyuki Hirayama 1-280 Higashi-Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. In Central Research Laboratory (72) Inventor Teruaki Takeuchi 1-280 Higashi Koigabo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 5D006 BB01 BB07 CA01 CA05 CA06 DA03 FA09

Claims (8)

[Claims] 1. A magnetic recording medium comprising a non-magnetic substrate, a Co alloy magnetic film formed on the non-magnetic substrate via an underlayer, and a protective film, wherein the underlayer is a lower underlayer on a side close to the substrate. The lower underlayer is a regular alloy layer having a B2 structure, and the upper underlayer is a Co-R having a hexagonal close-packed structure.
u _x -Cr _y (5 at% ≦ x ≦ 65 at%, 35 at% ≧
A magnetic recording medium comprising an alloy material satisfying y ≧ 0 at%). 2. The magnetic recording medium according to claim 1, wherein
The ordered alloy layer having the B2 structure includes NiAl, FeAl,
A magnetic recording medium comprising a material selected from FeV, CuZn, CoAl, and CuPd. 3. A magnetic recording medium comprising a non-magnetic substrate, a Co alloy magnetic film formed on the non-magnetic substrate via an underlayer, and a protective film, wherein the underlayer is a lower underlayer on a side closer to the substrate. The lower underlayer is a metal film having a body-centered cubic structure, and the upper underlayer is a Co-R having a hexagonal close-packed structure.
u _x -Cr _y (5 at% ≦ x ≦ 65 at%, 35 at% ≧
A magnetic recording medium comprising an alloy material satisfying y ≧ 0 at%). 4. The magnetic recording medium according to claim 3, wherein
The metal film having the body-centered cubic structure is Cr, Cr-Ti, C
A magnetic recording medium comprising a material selected from r-Mo, Cr-Nb, and Cr-V. 5. A magnetic recording medium comprising a non-magnetic substrate, a Co alloy magnetic film and a protective film formed on the non-magnetic substrate via an underlayer, wherein the underlayer is a lower layer, an intermediate layer, and an upper layer from a side close to the substrate. And the lower underlayer is M
gO or LiF, the intermediate underlayer metal film having an ordered alloy layer or body-centered cubic structure having a B2 structure, wherein the upper base layer is Co-Ru _x -Cr _y (5 having a hexagonal close-packed structure
at% ≦ x ≦ 65at%, 35at% ≧ y ≧ 0at%)
A magnetic recording medium characterized by comprising an alloy material of the following. 6. The magnetic recording medium according to claim 5, wherein
Si, Cr, Ti, N between the substrate and the lower underlayer.
b, Zr, Hf, Ta, SiOx, magnetic recording medium characterized in that a ZrO _2, SiN or adhesion enhancing layer consisting of a main component alloy. 7. The magnetic recording medium according to claim 1, wherein the magnetic film has Pt of 5 at% or more.
A magnetic recording medium comprising a Co alloy material having a hexagonal close-packed structure containing not more than 30 at%. 8. The magnetic recording medium according to claim 1, wherein the thickness of the upper underlayer is 1 nm or more and 50 nm or less.