JPH10214721A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having an improved magnetic efficiency. SOLUTION: This recording medium comprises a substrate 1, a yoke layer 3 which is able to transmit magnetic fluxes substantially in the same direction as the surface of the substrate 1, and a magnetic recording layer 4 formed on an upper surface of the yoke layer 3. An alloy film 2 is integrally, inseparably formed of the magnetic recording layer 4 and the yoke layer 3 with a boundary portion 5 existing therebetween. The magnetic recording layer 4 and the yoke layer 3 comprise, as essential elements, one or more of rare-earth elements selected from Y, La and lanthanide group elements; and iron. The boundary portion 5 is made up of a composition wherein the components of either one of the layers 3 and 4 are gradually decreased toward the other layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording device which is an external storage device of a computer and a magnetic recording medium used for storing music and images.

[0002]

2. Description of the Related Art Magnetic recording media are widely used not only as recording media for music and image data but also as external storage devices for computers. Considering, for example, an external storage device of a computer, in recent years, various methods have been devised in a recording method and a recording medium in order to enable high-density recording in a magnetic recording device. As an example, as a recording method, a perpendicular recording method has been proposed with respect to the conventional longitudinal recording. Further, in the recording medium, a two-layer or three-layer medium having different materials and magnetic properties is used in part.

[0003]

In the case of a perpendicular recording medium in which a soft magnetic permalloy or the like magnetic film is formed as a lower layer and a hard magnetic Co—Cr based film is formed as an upper layer, the hard magnetic film is Due to the influence of the crystallinity of the lower layer, it is difficult to have perpendicular anisotropy with respect to the film surface. Therefore, the film is formed by strictly controlling the alloy composition and sputtering conditions. Alternatively, a thin buffer layer is provided at the interface between the upper layer and the lower layer in order to eliminate the influence of the lower layer. In any case,
Not only does this increase the number of steps, but also significantly lowers the magnetic efficiency, which is a factor that lowers the recording / reproducing efficiency, the signal-to-noise ratio, and impairs the stability of the recording magnetization state. The present invention has been made in view of the above problems, and its purpose is to
It is an object of the present invention to provide a novel magnetic recording medium for the purpose of improving magnetic efficiency and simplifying a manufacturing process.

[0004]

In order to achieve the above-mentioned object of the present invention, the present invention basically provides a yoke layer for passing a magnetic flux on a substrate of a magnetic recording medium in substantially the same direction as the substrate surface. And a magnetic recording layer comprising a magnetic recording layer formed on an upper surface of the yoke layer, wherein an alloy film composed of the magnetic recording layer and the yoke layer is integrally formed, and Y,
A composition in which one or more rare earth elements of at least one element selected from the group consisting of La and a lanthanide element and iron are essential elements, and the component composition of one of the yoke layers is gradually reduced from one of the magnetic recording layer and the yoke layer. A magnetic recording medium having a boundary portion consisting of:

Specifically, in the above structure, the composition of the alloy film is composed of 3 to 15 at% of a rare earth element and the balance of iron,
Further, the composition of the alloy film is such that the rare earth element 3-15 at.
%, Co, Ni, Al, Si, Ti, V, Cr, Mn,
Also provided is a magnetic recording medium in which at least one element M of Zr, Nb, Mo, Ga, Sn, Hf, Ta, and W is 0.02 to 20 at% and the balance is iron.

The principle of construction of the magnetic recording medium according to the present invention in which the magnetic recording layer and the yoke layer are integrally formed is as follows. For example, by sputtering, the initial using Sm-Fe targets to form a Sm ₂ Fe ₁₇ film, adding a Fe-Ti targets in the middle and Sm ₂ Fe
Performs binary simultaneous sputtering with _17, SmFe ₁₁ Ti upper layer
Form a film. At this time, the soft magnetic Sm ₂ Fe ₁₇ crystal C
When the surface (001) is formed so as to be parallel to the substrate surface, the hard magnetic SmFe ₁₁ Ti upper layer is formed so that the C axis of the crystal is parallel to the substrate surface, and the hard magnetic recording layer is different in the direction parallel to the film surface. Shows anisotropy. In addition to this example, by appropriately selecting the alloy crystal structure and the component composition, it is possible to manufacture a magnetic film in which both hard and soft magnetism and anisotropy are controlled.

As the film forming method of the present invention, sputtering, vapor deposition, plating, laser deposition, CVD and the like can be used. The alloy film contains at least one rare earth element of the lanthanide group and iron as essential elements. With respect to the composition range, the coercive force is small when the rare earth element is less than 3%, and the coercive force required for the magnetic recording layer is small. Magnetic force cannot be obtained. On the other hand, if it exceeds 15%, the saturation magnetization decreases and the rare earth content increases, so that the oxidation resistance of the film is impaired.

Further, in addition to the rare earth element and iron, ferromagnetic C
o, Ni or Al, Si, Ti, V, Cr, Mn, Z
By adding one or more of r, Nb, Mo, Ga, Sn, Hf, Ta, and W, the crystal structure of the alloy can be stabilized and the magnetic characteristics can be adjusted. However, if the total amount of these elements is less than 0.02%, the effect of adjusting the magnetic properties is hardly observed, while if it exceeds 20%, the original crystal structure of the alloy cannot be maintained and the magnetic properties are impaired.

Further, the alloy film of the present invention is made of Th ₂ Zn ₁₇ , Th
₂ Ni ₁₇ , TbCu ₇ , ThMn ₁₂ , R ₃ (Fe, M)
It is formed by selecting various compounds such as type ₂₉ . For example, T
C of alloy of Sm ₂ Fe ₁₇ composition having h ₂ Zn ₁₇ crystal structure
On the surface (001), Ti-added Sm ₂ Fe ₁₇ Ti ₂
When an upper alloy film having a composition is formed, the upper layer has a ThMn ₁₂ type crystal structure from the comparison of crystal stability. Also, in this case, the lower alloy shows soft magnetism, the upper alloy shows hard magnetism, and its C axis is parallel to the film surface, and has in-plane anisotropy.

In another example, NdF having a ThMn ₁₂ structure is used.
C surface of the alloy of the e ₁₁ V composition on (001), the upper alloy film NdFe ₁₀ vmo same composition of ThMn ₁₂ structure with additionally added Mo is formed. In this case, the lower alloy shows an intermediate magnetism between soft magnetism and hard magnetism, and the upper alloy shows hard magnetism and has anisotropy in the direction perpendicular to the film surface.

The magnetic recording medium constructed as described above is not only excellent in smoothness because there is no disturbance at the boundary between the upper and lower layers, but also has no magnetic gap conventionally seen in a two-layer film. In addition, the recording / reproducing characteristics and the signal-to-noise ratio are high, and the stability of the recording magnetization state is excellent.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial sectional view of a magnetic recording medium according to the present invention. In FIG. 1, reference numeral 1 denotes a substrate made of glass or the like. On the upper surface of the substrate 1, a magnetic medium layer 2 is formed. The magnetic medium layer 2 comprises a yoke layer 3 attached on a substrate, a magnetic recording layer 4 on the surface, and a boundary portion 5 formed therebetween.

The substrate 1 is made of SiO ₂ glass having high mechanical strength and small expansion and contraction due to temperature change. The yoke layer 3 is made of a soft magnetic material or a ferromagnetic material whose axis of magnetic anisotropy is aligned in the plane direction of the substrate 1, both of which pass a magnetic flux in the same direction as the plane of the substrate 1. It is configured to be able to. Magnetic recording layer 4
Indicates that the yoke layer 3 is made of a soft magnetic material or the substrate 1
When the yoke layer 3 is made of a soft magnetic material, it can have anisotropy in the direction perpendicular to the plane of the substrate 1. The magnetic recording layer can have anisotropy in the plane direction and exhibit excellent hard magnetic characteristics in any case. The boundary portion 5 is not clearly separated from the yoke layer 3 and the magnetic recording layer 4 by a plane, but is in a state in which both are intermingled. The boundary between the two layers is formed by a configuration in which the composition of the other layer gradually decreases, and the details will be described later. The thickness of the magnetic recording layer is approximately 2 to 50% of the thickness of the entire yoke layer at the boundary between the magnetic recording layers.

The substrate 1 can be made of glass as described above, but as shown in FIG. 2, the substrate 6 can be made of aluminum. In this case, the substrate 6 and the magnetic medium layer 2 It is preferable to form a base film 7 made of a non-magnetic metal to repair defects on the surface of the aluminum substrate and absorb physical strain generated between the magnetic medium layer 2 and the substrate 6 at the same time. Further, the substrate 1 can be made of silicon.

[0015]

EXAMPLE An initial sputtering was carried out in an argon gas using an Sm-FeCo-V target to form a lower layer film on a glass substrate surface. The two-component simultaneous sputtering was performed while applying a magnetic field in the direction of 9.5a on the glass substrate.
An alloy film having a composition of t% Sm-18.2 at% Co-17.6 at% V-remaining Fe was formed to obtain a sample (A) of the present invention. This film has a ThMn _12- type crystal structure. The lower film is formed such that the C axis of the crystal is parallel to the substrate surface, and the upper film is formed such that the C axis of the crystal is perpendicular to the substrate surface due to the influence of the magnetic field. Was. As a result of magnetic measurement, both the upper layer and the lower layer showed hard magnetism. The upper layer had anisotropy perpendicular to the film surface and the lower layer had anisotropy in the direction parallel to the film surface. Separately, a sample having a conventional configuration in which a Co-Cr upper layer was provided on a lower layer of permalloy was manufactured, and this was used as a comparative sample (B). The coercive force of each alloy film was as shown in FIG. 3, and it was found that the sample of the present invention had excellent magnetic properties.

In this embodiment, as shown in FIG. 4, a hard magnetic yoke layer 3 showing anisotropy in the horizontal direction with respect to the substrate surface is formed on the upper layer of the substrate 1, and the uppermost layer is formed on the substrate surface with respect to the substrate surface. A magnetic recording layer 4 of a hard magnetic material exhibiting anisotropy in the vertical direction is formed.
The intermediate boundary portion 5 has a configuration in which the composition of the other layer gradually decreases toward one of the layers.

Embodiment 2 FIG. After performing initial sputtering in an argon gas using an Sm-Fe target, an additional Fe-Ti target is added to perform binary simultaneous sputtering with Sm-Fe, and 8.8 at% S is deposited on a silicon substrate.
An alloy film having a composition of m-4.2 at% Ti-remaining Fe was formed to obtain a sample (C) of the present invention. This film has a lower layer of Th ₂ Z
It had an n ₁₇ -type crystal structure, its approximate composition was Sm ₂ Fe ₁₇ , and the C-plane (001) of the crystal was formed parallel to the substrate surface. On the other hand, the upper layer has a ThMn ₁₂ type crystal structure, the approximate composition is SmFe ₁₁ Ti, and the C
The axis was formed parallel to the substrate surface. The lower layer showed soft magnetism, the upper layer showed hard magnetism, and its anisotropic direction was parallel to the film surface. The coercive force of this sample (C) was 26
At 30 Oe, the lower layer was 1.1 Oe.

This magnetic recording medium is, as shown in FIG.
The lower layer film becomes the yoke layer 3 which exhibits soft magnetism and allows magnetic flux to pass. The upper layer film forms the magnetic recording layer 4 which is hard magnetic and has anisotropy in the direction parallel to the film surface. Further, the yoke layer 3 and the magnetic recording layer 4 are integrally formed as an integral part, and the boundary portion 5 has a configuration in which the composition of the other layer gradually decreases toward one of the layers.

Embodiment 3 FIG. When sputtering is performed in an argon gas while applying a magnetic field in a direction perpendicular to the substrate surface using two types of targets, Sm-Fe and Fe-Ti, the sputtering rate from the Fe-Ti target is changed over time. 9.2at% Sm-4.5at% T on an aluminum substrate that has been raised and deposited and electroless nickel plated.
Forming an alloy film having i-remaining Fe composition to prepare the sample (D) of the present invention
And In this film, the lower layer was mainly governed by the Th ₂ Zn ₁₇ type crystal structure, and the C axis of the crystal was formed parallel to the substrate surface due to the effect of the application of a magnetic field. On the other hand, the upper layer is Th
It was governed by the Mn ₁₂ type crystal structure, and the C axis of the crystal was formed in a direction perpendicular to the substrate surface. Therefore, the magnetism changed from soft magnetic to hard magnetic from the lower layer to the upper layer, and the direction of anisotropy was inclined from the inside of the film surface to the direction perpendicular to the film surface.

In this embodiment, as shown in FIG. 6, the lowermost film becomes the yoke layer 3 exhibiting anisotropy in the direction parallel to the substrate, and the boundary portion 5 becomes anisotropic from the lower film toward the upper film. Is gradually turned from the horizontal direction to the vertical direction, and the uppermost layer becomes the magnetic recording layer 4 exhibiting anisotropy in the direction perpendicular to the substrate.

As described above, the present invention has been described with reference to the above-described embodiments and examples. However, various modifications and applications are possible within the scope of the present invention, and these modifications and applications are excluded from the scope of the present invention. It does not do.

[0022]

As described in detail above, the present invention provides
A magnetic recording medium comprising: a yoke layer that allows a magnetic flux to pass in substantially the same direction as the surface of the substrate; and a magnetic recording layer that is formed on an upper surface of the yoke layer. One of the magnetic recording layer and the yoke layer, in which an alloy film composed of the yoke layer is integrally formed and contains at least one rare earth element of Y, La, and lanthanide elements and iron as essential elements. By providing a magnetic recording medium having a boundary portion in which the composition of one layer gradually decreases from the other layer toward the other layer, there is no disturbance at the boundary surface, the smoothness is excellent, and a magnetic gap is generated. Since it is not used, it is effective in improving the recording / reproducing characteristics and the signal-to-noise ratio. Further, there is also an effect that the production becomes simple because there is no need to form two types of magnetic layers.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a magnetic recording medium of the present invention.

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

FIG. 3 is a comparison table diagram between the first embodiment of the present invention and a conventional example.

FIG. 4 is a sectional view showing a first embodiment of the present invention.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

 1 ... substrate 2 ... magnetic medium layer 3 ... yoke layer 4 ... magnetic recording layer 5 ... boundary 6 ... substrate 7 .... Undercoat film

Claims (3)

[Claims] 1. A magnetic recording medium comprising: a yoke layer on a substrate of a magnetic recording medium that allows a magnetic flux to pass in substantially the same direction as the substrate surface; and a magnetic recording layer formed on an upper surface of the yoke layer. An alloy film composed of the magnetic recording layer and the yoke layer is formed integrally and inseparably, and the magnetic recording layer and the yoke layer containing at least one rare earth element of one of Y, La, and lanthanide elements and iron as essential elements. A magnetic recording medium having a boundary portion configured such that the component composition of one layer gradually decreases from one of the layers toward the other layer. 2. The method according to claim 1, wherein the composition of the alloy film is 3-15 at.
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is composed of%, with the balance being iron. 3. The composition of the alloy film is a rare earth element 3-15 at.
%, Co, Ni, Al, Si, Ti, V, Cr, Mn,
2. The magnetic recording medium according to claim 1, wherein at least one element M among Zr, Nb, Mo, Ga, Sn, Hf, Ta, and W comprises 0.02 to 20 at%, with the balance being iron. .