JP2001093139A - Magnetic recording medium and magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium excellent in noise properties. SOLUTION: This magnetic recording medium has a first base film 2, a second base film 3, a non-magnetic intermediate film 4 and a vertical magnetic film 5 having an easily-magnetized axis oriented essentially vertically to a substrate 1 which are laminated on the substrate in this order and the first base layer 2 consists of a material having B2 structure.

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 and a magnetic recording / reproducing apparatus using the magnetic recording medium.

[0002]

2. Description of the Related Art Most magnetic recording media currently on the market are in-plane magnetic recording media in which the axis of easy magnetization in a magnetic film is mainly oriented horizontally to a substrate. In such an in-plane magnetic recording medium, when the recording density is increased, the bit volume becomes too small, and the reproduction characteristics may be deteriorated due to the thermal fluctuation effect. Also, when the recording density is increased, medium noise may increase due to the influence of the demagnetizing field at the recording bit boundary. In contrast, so-called perpendicular magnetic recording media, in which the easy axis of magnetization in the magnetic film is mainly oriented perpendicular to the substrate, are less affected by the demagnetizing field at the bit boundaries even when the recording density is increased, and the boundaries are sharp. Low magnetic noise is possible due to the formation of a large recording magnetic domain, and the high recording density is possible even with a relatively large bit volume. A medium structure suitable for perpendicular magnetic recording has been proposed. For example, JP-A-58-77025 and JP-A-58-141435 disclose the use of Ti as a material for an underlayer of a perpendicular magnetic film made of a Co alloy material. Japanese Patent Application Laid-Open No. 8-180360 discloses that an alloy composed of Co and Ru is used as a material of the underlayer.

[0003]

In recent years, there has been a demand for higher recording densities of magnetic recording media, and accordingly, improvement of noise characteristics has been demanded. However, the conventional magnetic recording medium has never been satisfactory in terms of noise characteristics, and a magnetic recording medium having more excellent noise characteristics has been demanded. The present invention has been made in view of the above circumstances, and has as its object to provide a magnetic recording medium and a magnetic recording / reproducing apparatus having excellent noise characteristics.

[0004]

According to the magnetic recording medium of the present invention, a first underlayer and a second underlayer are provided on a substrate, on which a magnetization easy axis is mainly oriented perpendicular to the substrate. A magnetic film is provided, and the first underlayer is made of a material having a B2 structure. The first underlayer is made of NiAl, FeAl, CoFe, CoZr, N
one or two of iTi, AlCo, and AlMn
It can be made of a material mainly composed of at least one kind of alloy. The first underlayer is made of NiAl, FeAl, Co
Fe, CoZr, NiTi, AlCo, and AlMn
When the material is composed of a material containing any of the binary alloys as a main component, the content of each of the two components constituting the binary alloy is 40 to 60 at%, preferably 45 to 60 at%. Preferably, it is 55 at%. The second underlayer is preferably made of a material having an hcp structure, and includes Ti, Zr, Ru, Re, Y, Gd, and Tb.
Among them, a material containing one or two or more kinds as a main component can be used. The perpendicular magnetic film is made of Co / Cr / Pt, C
o / Cr / Ta system, Co / Cr / Pt / X system (X: T
a, Zr, Nb, Cu, Re, Ni, and one of B
Or two or more of them). Preferably, a non-magnetic intermediate film having an hcp structure is provided between the second underlayer and the perpendicular magnetic film. It is preferable that the thickness of the first underlayer is 500 ° or less. The thickness of the perpendicular magnetic film is 100 to 1000 Å
It is preferred that The magnetic recording / reproducing apparatus of the present invention includes a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium has a first underlayer and a second underlayer provided on a substrate. A perpendicular magnetic film having an axis of easy magnetization oriented mainly perpendicular to the substrate is provided thereon;
The base film is made of a material having a B2 structure.

[0005]

FIG. 1 shows an embodiment of a magnetic recording medium according to the present invention. The magnetic recording medium shown in FIG.
On a substrate 1, a first base film 2, a second base film 3, a nonmagnetic intermediate film 4, a perpendicular magnetic film 5, and a protective film 6 are sequentially formed. As the substrate 1, an aluminum alloy substrate (hereinafter, referred to as “NiP plated Al substrate”) having a NiP plated film generally used as a substrate for a magnetic recording medium, a glass substrate, a ceramic substrate, a carbon substrate,
A flexible resin substrate, a substrate in which a NiP film is formed on these substrates by plating or sputtering, or the like can be used.

The first underlayer 2 is used to improve the coercive force and squareness, and to improve the noise characteristics of the magnetic recording medium, and is made of a material having a B2 structure. Materials having the B2 structure include NiAl, FeAl, CoFe,
Those containing one or more alloys of CoZr, NiTi, AlCo, and AlMn as main components can be used. In addition, Cr, Nb, V, W, Mo
Alternatively, a material to which an element such as the above is added can be used.

The above binary alloys (NiAl, FeAl, C
oFe, CoZr, NiTi, AlCo, AlMn), when using a material containing any one of the main components, the content of each of the two components constituting the alloy is 40%.
６０60 at% (preferably 45 to 55 at%). If the content is less than the above range or exceeds the above range, B2 in the first underlayer 2
The structure may be disturbed, and the effect of improving noise characteristics may be reduced.

Preferably, the thickness of the first underlayer 2 is determined as follows. FIG. 2 shows the thickness of the first underlayer 2 and (000) of the perpendicular magnetic layer 5 in the magnetic recording medium having the above configuration.
2) It is a graph which shows the relationship with the orientation of a surface. In this graph, the horizontal axis represents the thickness of the first underlayer 2, and the vertical axis represents the X-ray diffraction intensity corresponding to the (0002) plane of the perpendicular magnetic film 5. As shown in this graph, the X-ray diffraction intensity reaches a peak when the thickness of the first base film 2 is 25 °,
Thereafter, the thickness becomes smaller as the thickness of the first base film 2 is increased. From this graph, the perpendicular orientation of the perpendicular magnetic film 5 is as follows.
The thickness of the first base film 2 is about 25 °, that is, 15 to 40.
It can be seen that the temperature increases when 下地 (particularly 20 to 30 °), and gradually decreases when the thickness of the first underlayer 2 is further increased. Hereinafter, a region where the thickness of the first base film 2 is about 25 ° (that is, 15 to 40 °) is referred to as a region A.

FIG. 3 shows the coercive force Hc (Oe) and SNR of the magnetic recording medium when a ring-type head, which is a magnetic head used for a normal longitudinal magnetic recording medium, is used.
It is a graph which shows the result of having measured (dB). In this graph, the horizontal axis indicates the thickness of the first underlayer 2, and the vertical axis indicates coercive force (Hc) and SNR. From this graph,
It can be seen that Hc increases sharply until the thickness of the first underlayer 2 reaches the region A, and thereafter increases very little. As for the SNR, the thickness of the first base film 2 increases until reaching the region A, and once becomes substantially constant, then increases again in the region where the thickness of the first base film 2 is 80 to 500 °, It can be seen that after passing through this region, it slightly decreases and becomes almost constant. Hereinafter, the thickness of the first underlayer 2 is 80
The area of Å500 ° is called a B area. Among these B regions, in particular, the thickness is 80 to 300 °, and more preferably 80 to 150 °.
In the range of Å, the SNR has a particularly high value.

From this graph, it can be seen that when a magnetic head (ring type head) used for a normal in-plane magnetic recording medium is used, the perpendicular magnetic film 5 has a higher perpendicular orientation than the region A where the perpendicular orientation is higher. It can be seen that excellent SNR characteristics can be obtained in a low B region. The reason that the SNR characteristic is improved in the region B having a low vertical orientation is that the magnetization direction is mostly vertical in the region A having a high vertical orientation,
In the region, since the orientation of the magnetic film 5 becomes somewhat random, the magnetization in the in-plane direction also increases, and a loop-shaped magnetization curve composed of the perpendicular direction and the in-plane direction is formed, thereby stabilizing the magnetization. , The output is considered to be improved.

In a region where the thickness of the first underlayer 2 is larger than the region B, Hc is higher than that in the region B.
It is considered that the reproduction output level has also increased with an increase in Hc. For this reason, in the region where the thickness of the base film 2 is larger than the region B, the SNR, which is the ratio between the reproduction output and the noise, decreases only slightly, but the increase in the noise is considered to be remarkable. Can be From this,
By setting the thickness of the first base film 2 to the region B,
It is considered that the noise level can be suppressed lower than when the thickness of the base film 2 is set to a value exceeding the region B.

From the above results, the thickness of the first underlayer 2 is
It can be seen that it is preferable to set as follows. When it is assumed that a ring-type head, which is a magnetic head used for a normal longitudinal magnetic recording medium, is used, the first underlayer 2
Is a thickness corresponding to the above-mentioned region B, 80 to 50.
0 ° (preferably 80-300 °, more preferably 8 °
0 to 150 °) is preferable because the SNR characteristics can be further improved. If the thickness is less than the above range, the SNR characteristics deteriorate. This is because, when the thickness is less than the above range, the magnetization in the in-plane direction is less likely to occur due to the enhancement of the vertical orientation, and as a result, the output improving effect by the formation of the above-mentioned loop-shaped magnetization curve is obtained. It is thought that this is because it is difficult to be performed. If the thickness exceeds the above range, the noise characteristics deteriorate. This is because if the thickness exceeds the above range, the crystal grains become coarse in the first underlayer 2, so that the nonmagnetic intermediate film 4 and the perpendicular magnetic film 5 formed on the underlayer 2 also become large. This is considered to be because the coarsening of the crystal grains progresses, thereby increasing noise.

The second underlayer 3 is for increasing the vertical orientation of the non-magnetic intermediate film 4 and the perpendicular magnetic film 5 and is formed of hcp.
It is preferable to use a material having a structure. The constituent material of the second base film 3 is Ti, Zr, Ru, Re, Y, G
Examples of the material include one or more of d and Tb as main components. As this material, T
Any of i, Zr, Ru, Re, Y, Gd, and Tb can be used as a single substance, or they can be used in consideration of lattice matching (matching) with the nonmagnetic intermediate film 4 and the perpendicular magnetic film 5. Cr, Co, Fe, Ni as material
Alternatively, an alloy to which the like has been added can be used. The second base film 3 may have a partially fcc structure.

The non-magnetic intermediate film 4 is for increasing the coercive force of the medium, and is made of a non-magnetic material having an hcp structure. The material of the non-magnetic intermediate film 4 is Co /
Cr system, Co / Cr / Pt system, Co / Cr / Ta system, C
o / Cr / Pt / X system (X: Ta, Zr, Nb, Cu,
It is preferable to use any one of Re, Ni, and B). In particular, Cr
Content of 25 to 50 at%, Pt content of 0 to 15
It is preferable to use a material whose main component is a Co alloy containing at%, X content of 0 to 10 at%, and the balance being Co. The nonmagnetic intermediate film 4 may have a single-layer structure or a multi-layer structure. In the case of a multilayer structure, a plurality of the same or different materials selected from the above materials may be stacked.

The thickness of the non-magnetic intermediate film 4 is preferably set to 500 ° or less. If the thickness exceeds 500 °, the magnetic particles in the perpendicular magnetic film 5 are likely to be coarsened, and the noise characteristics are undesirably reduced. Non-magnetic interlayer 4
Is more preferably 20 to 300 °. The thickness of the non-magnetic intermediate film 4 in the case of a multi-layer is
It is desirable that the total be 500 ° or less, preferably 50 to 200 °.

The perpendicular magnetic film 5 is a film made of a magnetic material whose easy axis of magnetization is mainly oriented in a direction perpendicular to the substrate, and is made of a Co / Cr / Pt system, Co / C
r / Ta system, Co / Cr / Pt / X system (X: Ta, Z
It is preferable to use any one of r, Nb, Cu, Re, Ni, and B). In particular, it is preferable to use a Co alloy having a Cr content of 13 to 28 at%, a Pt content of 0 to 15 at%, an X content of 0 to 5 at%, and a balance of Co. If the content of each component is out of the above range, it is not preferable because the noise characteristics or the reproduction output are reduced.

The thickness of the perpendicular magnetic film 5 is 100 to 1000
Å is preferred. The thickness of the perpendicular magnetic film 5 is 100 mm
If it is less than 1, sufficient magnetic flux cannot be obtained, and the reproduction output decreases. On the other hand, if the thickness of the perpendicular magnetic film 5 exceeds 1000 °, the magnetic particles in the perpendicular magnetic film 5 become coarse and noise characteristics deteriorate, which is not preferable. More preferably, the thickness of the perpendicular magnetic film 5 is 200 to 700 °. This is because, when the thickness of the perpendicular magnetic film 5 is in this range, the reproduction output can be further improved, and the magnetic particles in the perpendicular magnetic film 5 can be prevented from being roughened, and the noise characteristics can be further improved. .

The protective film 6 prevents corrosion of the perpendicular magnetic film 5, prevents damage to the medium surface when the head comes into contact with the medium, and ensures lubrication characteristics between the head and the medium. Conventionally known materials can be used, for example, C, S
A single composition of iO ₂ or ZrO ₂ or a composition containing these as a main component and containing other elements can be used. The thickness of the protective film 6 is desirably 10 to 100 °. Further, on the protective film 6, perfluoropolyether, fluorinated alcohol,
It is preferable to provide a lubricating film made of a fluorinated carboxylic acid or the like.

To manufacture the magnetic recording medium having the above configuration,
A first underlayer 2, a second underlayer 3, a non-magnetic intermediate film 4, and a perpendicular magnetic film 5 are sequentially formed on a substrate 1 by a technique such as sputtering, vacuum deposition, or ion plating, and then a protective film 6 is formed. It is preferably formed by a plasma CVD method, an ion beam method, or a sputtering method. When forming the first underlayer 2, it is preferable to use a sputtering target made of a material having a B2 structure. As this material, those described above can be used. Also,
In order to form a lubricating film, a conventionally known method such as a dipping method and a spin coating method can be adopted.

In the magnetic recording medium having the above structure, the first
Since the base film 2 is made of a material having the B2 structure, the coercive force and the squareness can be improved, and the noise characteristics can be improved. The reason why the above effects can be obtained by providing the first base film 2 made of the material having the B2 structure is not clear, but it can be assumed that the reason is as follows. That is, the perpendicular magnetic film 5 formed on the first base film 2 via the second base film 3 and the non-magnetic intermediate film 4 grows under the influence of the first base film 2 having the B2 structure. It is considered that in the perpendicular magnetic film 5 grown under the influence of the first underlayer 2 having the B2 structure, the crystal grains are refined, isolated, and made uniform. Thus, it is considered that the coercive force and the squareness ratio are increased, and a recording magnetic domain having a sharp boundary is formed, so that noise can be reduced.

Further, by forming the second underlayer 3 from a material having an hcp structure, the vertical orientation of the perpendicular magnetic film 5 formed on the second underlayer 3 via the non-magnetic intermediate film 4 is improved. And noise characteristics and coercive force can be improved. This effect is achieved by the second base film 3 having the hcp structure.
Is considered to be obtained by improving the lattice matching between the first underlayer 2 and the non-magnetic intermediate layer 4.

Further, by disposing the non-magnetic intermediate film 4 having the hcp structure between the second underlayer 3 and the perpendicular magnetic film 5, disturbance of crystal orientation during initial growth of the perpendicular magnetic film 5 is prevented. To improve the crystal orientation of the perpendicular magnetic film 5,
High coercive force and low noise can be achieved.

In the present invention, as shown in FIG. 4, a soft magnetic film 12 can be provided between the substrate 1 and the first underlayer 2. As a constituent material of the soft magnetic film 12, a Co amorphous material (for example, an alloy such as CoZrNb, CoTaNb, Permalloy, or Sendust) can be used. The thickness of the soft magnetic film 12 is 50 nm or more (preferably 100 nm).
Above, more preferably 200 nm or more). When the thickness is less than the above range, the loop-shaped magnetization curve is hardly formed.

FIG. 5 shows an example of a magnetic recording and reproducing apparatus using the above magnetic recording medium. The magnetic recording / reproducing apparatus shown here includes a magnetic recording medium 7 having a configuration shown in FIG. 1, a medium driving unit 8 for driving the magnetic recording medium 7 to rotate, a magnetic head 9 for recording / reproducing information on / from the magnetic recording medium 7, A head drive unit 10 and a recording / reproducing signal processing system 11 are provided.
The recording / reproducing signal processing system 11 can process input data and send a recording signal to the magnetic head 9, or can process a reproducing signal from the magnetic head 9 and output data. As the magnetic head 9, a ring type head used for a normal longitudinal magnetic recording medium can be exemplified. In the magnetic head 9, the material of the portion where the gap is formed, the gap length, the writing conditions, and the like are appropriately set. For example, the gap length of the element in the recording section of the ring type head is 0.08 μm or more, preferably 0.1 μm.
m or more, more preferably 0.12 μm or more. Further, it is preferable that the gap length of the element in the recording portion of the ring type head is 0.4 μm or less.

According to the magnetic recording / reproducing apparatus, since the magnetic recording medium is used, the coercive force and the squareness can be improved, and the noise characteristics can be improved. Therefore, high recording density can be achieved.

Incidentally, the magnetic recording medium having the above-mentioned structure is: hc
Although the non-magnetic intermediate film 4 made of a material having a p-structure is provided, the magnetic recording medium of the present invention is not limited to this, and the non-magnetic intermediate film 4 may not be provided. FIG. 6 shows a magnetic recording medium in which the non-magnetic intermediate film 4 is not provided. In the present specification, the main component means that the component is contained in an amount exceeding 50 at%.

[0027]

EXAMPLES (Test Example 1) Hereinafter, the working effects of the present invention will be clarified by showing specific examples. Glass substrate 1 (OHARA TS-1
OSX) was set in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anelva). The chamber was evacuated to a vacuum attainment of 2 × 10 ⁻⁷ Pa and the substrate 1 was heated to 200 ° C., and then Ni-50 at% Al (Al content: 50 at%,
The balance: Ni. Hereinafter, it is referred to as “Ni50Al”. ), A second underlayer 3 made of Ru and having an hcp structure, a non-magnetic intermediate film 4 made of Co-40 at% Cr (Co40Cr), Co-22 at% Cr-12 at%.
A perpendicular magnetic film 5 made of Pt-2at% Ta (Co22Cr12Pt2Ta) was sequentially formed by sputtering. On the perpendicular magnetic film 5, a carbon protective film 6 having a thickness of 70 ° was formed by using a plasma CVD method.

(Test Examples 2 to 24) Magnetic recording media were manufactured with the materials and thicknesses of each film as shown in Table 1.

The magnetostatic properties of the magnetic recording media of Test Examples 1 to 24 were measured using a vibration type magnetic property measuring device (VSM). In addition, the electromagnetic conversion characteristics of these magnetic recording media are
GUZIK read / write analyzer RWA163
2 and spin stand S1701MP. To evaluate the electromagnetic conversion characteristics, a composite thin film magnetic recording head having a giant magnetoresistive (GMR) element in the reproducing section was used as the magnetic head, and the recording conditions were set to a linear recording density of 250 k.
The measurement was performed as FCI. The magnetic head used for the evaluation of the electromagnetic conversion characteristics is the same as the magnetic head used for a normal longitudinal magnetic recording medium. Also X
As a result of the line diffraction test, it was confirmed that the first underlayer 2 had a B2 structure in each of the test examples. Table 1 shows the measurement results of the magnetostatic characteristics and the electromagnetic conversion characteristics of the magnetic recording media of Test Examples 1 to 24. In Table 1, Mr /
Ms indicates a squareness ratio, and Co (0002) intensity indicates an X-ray diffraction intensity corresponding to the (0002) plane of the perpendicular magnetic film 5.

[0030]

[Table 1]

From Table 1, it can be seen that the magnetic recording medium having the first underlayer 2 provided with the first underlayer 2 has better noise characteristics (SNR) and coercive force (Hc) than the magnetic recording medium without the first underlayer 2. Indicates that excellent results were obtained.

[0032]

As described above, in the magnetic recording medium of the present invention, since the first underlayer is made of the material having the B2 structure, the coercive force and the squareness can be improved.
Noise characteristics can be improved. Further, according to the magnetic recording / reproducing apparatus of the present invention, since the magnetic recording medium is used, the coercive force and the squareness can be improved, and the noise characteristics can be improved. Therefore, high recording density can be achieved.

[Brief description of the drawings]

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

FIG. 2 shows the thickness of a first underlayer and the thickness (00) of a perpendicular magnetic film.
It is a graph which shows the relationship with the orientation of 02) plane.

FIG. 3 is a graph showing the results of measuring the coercive force (Hc) and SNR of the magnetic recording medium when a magnetic head used for a normal longitudinal magnetic recording medium is used.

FIG. 4 is a partial sectional view showing a second embodiment of the magnetic recording medium of the present invention.

FIG. 5 is a schematic configuration diagram showing an example of a magnetic recording / reproducing apparatus using the magnetic recording medium shown in FIG.

FIG. 6 is a partial sectional view showing a third embodiment of the magnetic recording medium of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... 1st base film, 3 ... 2nd base film, 4 ...
Non-magnetic intermediate film, 5 ... perpendicular magnetic film

Claims (9)

[Claims] 1. A first underlayer and a second underlayer are provided on a substrate, and a perpendicular magnetic film whose easy axis is mainly oriented perpendicular to the substrate is provided thereon. A magnetic recording medium comprising a material having a B2 structure. 2. The magnetic recording medium according to claim 1, wherein the first underlayer is made of NiAl, FeAl, CoFe, C
one of oZr, NiTi, AlCo, and AlMn
A magnetic recording medium comprising a material mainly containing one or more alloys. 3. The magnetic recording medium according to claim 1, wherein the second underlayer is made of a material having an hcp structure. 4. The magnetic recording medium according to claim 1, wherein the second underlayer is made of Ti, Zr,
One or two of Ru, Re, Y, Gd, and Tb
A magnetic recording medium comprising a material containing at least one species as a main component. 5. The magnetic recording medium according to claim 1, wherein the perpendicular magnetic film is made of Co / Cr /
Pt system, Co / Cr / Ta system, Co / Cr / Pt / X system (X: Ta, Zr, Nb, Cu, Re, Ni, and B
A magnetic recording medium comprising one or more of the above alloys. 6. The magnetic recording medium according to claim 1, wherein a nonmagnetic intermediate film having an hcp structure is provided between the second underlayer and the perpendicular magnetic film. A magnetic recording medium characterized by the above-mentioned. 7. The magnetic recording medium according to claim 1, wherein the thickness of the first underlayer is 500 °.
A magnetic recording medium characterized by the following. 8. The magnetic recording medium according to claim 1, wherein the perpendicular magnetic film has a thickness of 100 to 100.
A magnetic recording medium having a thickness of 1000 °. 9. A magnetic recording medium comprising: a magnetic recording medium; and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is provided with a first underlayer and a second underlayer on a substrate. A magnetic recording / reproducing apparatus, comprising: a perpendicular magnetic film having an axis of easy magnetization oriented mainly perpendicular to a substrate; and a first underlayer made of a material having a B2 structure. .