JP3429777B2 - Magnetic recording medium and magnetic storage device using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to high density recording, specifically, a magnetic storage device having a recording density of 2 gigabits per square inch, and a low noise thin film magnetic recording for realizing the same. Regarding the medium.

BACKGROUND ART The demand for large capacity magnetic storage devices is currently increasing more and more. As a conventional magnetic head, an electromagnetic induction type magnetic head utilizing a voltage change accompanying a temporal change of magnetic flux has been used. This is for both recording and reproduction with one head. On the other hand, in recent years, a recording head and a reproducing head are separately provided, and a composite head using a magnetoresistive head having high sensitivity for the reproducing head is rapidly being adopted. The magnetoresistive head uses the fact that the electric resistance of the head element changes as the leakage magnetic flux from the medium changes. Also, the giant magnetoresistive effect,
Alternatively, the development of a head with higher sensitivity utilizing the spin valve effect is under way. These are the effects that the relative directions of the magnetizations of the plurality of magnetic layers via the non-magnetic layer are changed by the leakage magnetic field from the medium, which changes the electric resistance. Currently, magnetic recording media that have been put into practical use use CoCrPt, CoCrTa, CoNiCr, and other alloys containing Co as the main component for the magnetic layer. Since these Co alloys have a hexagonal close-packed structure (hcp structure) with the easy axis of magnetization in the c-axis direction, a crystal orientation in which the c-axis is in the in-plane direction is desirable for the in-plane magnetic recording medium. However, since such an orientation is unstable, it generally does not occur even if Co is directly formed on the substrate.
Therefore, the Cr (100) plane that has a body-centered cubic structure (bcc structure) is Co
Taking advantage of its good compatibility with the (11.0) plane, a (100) -oriented Cr underlayer is first formed on the substrate, and a Co alloy layer is epitaxially grown on the underlayer to form a c-axis on the Co alloy layer. A method of taking an inward (11.0) orientation is used. In order to further improve the matching at the interface between the Co alloy magnetic layer and the Cr underlayer, a method of adding a second element to Cr and increasing the lattice spacing of the Cr underlayer is used. This further increases the Co (11.0) orientation and can increase the coercive force. An example of such a technique is to add V, Ti or the like as shown in JP-A-62-257618 and JP-A-63-197018.

Along with the high coercive force of the recording medium, low noise is an essential factor for increasing the recording density. The medium noise is mainly due to the zigzag-shaped magnetization transition region generated between recording bits. Smoothing of this transition region is necessary to reduce medium noise. For this purpose, it is known that miniaturization of magnetic crystal grains and homogenization of crystal grain size are effective.

The magnetoresistive head as described above has an extremely high reproduction sensitivity and is suitable for high density recording. However, since not only the reproduced signal from the magnetic recording medium but also the sensitivity to noise are increased at the same time, the recording medium is required to have lower noise than ever before. In order to reduce the medium noise, it is necessary to make the magnetic crystal grains finely crystallized and uniform as described above. To that end, it is effective to microcrystallize and homogenize the underlayer. The addition of the second element to the Cr underlayer, which is seen in the above-mentioned known example, is a technique for increasing the lattice constant of the underlayer, and does not make the crystal grains of the underlayer fine and uniform.
Therefore, it is effective in improving the coercive force, but not effective in reducing the medium noise.

In addition, when glass is used as the substrate, the media noise increases because the crystal grains of the magnetic layer grow larger than when using a conventional NiP-plated A1 alloy substrate (hereinafter abbreviated as A1 substrate). , Electromagnetic conversion characteristics are inferior. On the other hand, Japanese Unexamined Patent Publication No. 4-153910 discloses a technique for making crystal grains of a magnetic layer fine by forming an amorphous or microcrystalline film between a glass substrate and a Cr alloy underlayer. However, there is no effect on making the crystal grain size uniform, and sufficient electromagnetic conversion characteristics have not been obtained.

In order to show good electromagnetic conversion characteristics even at such high recording density, the hcp (11.0) orientation of the Co alloy magnetic layer must be maintained.
It is necessary to reduce the crystal grain size, reduce the grain size distribution, and reduce the medium noise.

Even if a magnetic disk device is manufactured by combining the above-mentioned low-noise magnetic recording medium and a highly sensitive magnetoresistive head, a sufficient electromagnetic conversion characteristic cannot always be obtained. This is because the magnetic head and the magnetic recording medium have been developed separately, and it has not been sufficiently considered until now how to realize a high recording density as a magnetic disk device.

The purpose of this research is to solve the above problems and to provide a magnetic storage device having a recording density of 2 gigabits or more per square inch and high reliability, and a low noise magnetic recording medium suitable for high density recording. To provide.

DISCLOSURE OF THE INVENTION The present invention comprises a magnetic recording medium having a magnetic layer formed on a substrate through a single layer or a plurality of underlayers, a drive unit for driving the magnetic layer in the recording direction, a recording unit and a reproducing unit. A magnetic storage device having a magnetic head, means for moving the magnetic head relative to the magnetic recording medium, and recording / reproducing signal processing means for inputting a signal to the magnetic head and reproducing an output signal from the magnetic head. In, the reproducing portion of the magnetic head is composed of a magnetoresistive effect magnetic head,
At least one of the single underlayer or the plurality of underlayers of the magnetic recording medium contains at least one element selected from the first group consisting of Cr, Mo, V, and Ta as a main component, and
The object described above is achieved by using a layer made of an alloy material containing at least one element selected from the second group consisting of B, C, P and Bi.

By adding at least one element selected from the second group to the underlayer containing at least one element selected from the first group as a main component, the crystal grains of the underlayer become fine. , The particle size is made uniform. Therefore, the crystal grains of the magnetic layer formed on the underlayer are also miniaturized and made uniform, and the medium noise can be reduced. Figure 1 shows the Cr-15at% Ti underlayer, or Cr-14.3at% Ti-5at% B with 5at% of B added to it.
Br × t of media using underlayer and normalized media noise, and
The S / N relationship is shown. Incidentally, these media were manufactured under various film configurations and process conditions so that the coercive force is almost the same. Here, the numbers shown before the element symbols indicate the concentration of each element in atomic percentage (at%). The standardized medium noise is a value obtained by normalizing the medium noise by the output of the isolated reproduction wave and the track width.
The medium noise is relatively evaluated by this value. The normalized media noise is about 15% lower when using the CrTiB underlayer, and the S / N is also higher when using the CrTiB underlayer, regardless of the value of Br × t. At this time, the CrTiB underlayer has a bcc structure and has a (100) orientation, similar to the CrTi underlayer.
The hcp (11.0) orientation does not collapse.

FIG. 2 shows the relationship between the B concentration added to the Cr-15 at% Ti-B underlayer and the normalized medium noise. Although the medium noise is reduced by adding B, this effect disappears when the B concentration exceeds 20 at%. This is because the crystallinity of the magnetic layer is destroyed due to the deterioration of the crystallinity of the underlayer. Also, if the B concentration is less than 1 at%, the grain refinement and homogenization are insufficient, and the effect of noise reduction is small.

The effect of reducing the noise was confirmed when the elements of the second group other than B were added, but when P is added, the noise is remarkably reduced as in the case where B is added. Met. On the other hand, when C was added, the coercive force and coercive force squareness ratio S * were significantly improved, and when Bi was added, a medium with excellent corrosion resistance was obtained. The addition concentration of these elements is also preferably 1 at% or more and 20 at% or more, but when 2 to 8 at% is added, a medium with particularly low noise can be obtained.

In addition to Ti, V, Mo and the like can be cited as elements added to the underlayer in order to improve the lattice matching property at the interface between the underlayer and the Co alloy magnetic layer and improve the magnetic characteristics. These CrV
Even when the elements of the second group are added to the underlayer of the alloy or CrMo alloy, the crystal grain size of the underlayer becomes finer and more uniform as in the case of CrTi, and the noise reduction effect can be confirmed. It was In particular, the medium in which the second group of elements is added to the CrV underlayer is
The overwrite characteristics are better than those of media added to the CrTi or CrMo underlayer. When the second group of elements is added to the CrMo underlayer, it exhibits strong bcc (100) orientation and good crystallinity even at relatively low temperatures. For this reason, the carbon protective film can be formed at a low temperature, so that the film quality is improved and a medium having better CSS characteristics than when using another underlayer can be obtained. Comprehensively comparing, the media using the underlayer of B-added CrTi alloy to improve the lattice matching,
The axis of easy magnetization of the Co alloy is strongly oriented in the in-plane direction, and grain refinement and homogenization are most noticeable. Therefore, high resolution and low noise can be achieved at the same time, and a medium exhibiting particularly excellent recording and reproducing characteristics can be obtained.

The magnetic layer of the magnetic recording medium is CoCrPt, CoCrPtTa, CoC.
Although alloys with a hcp structure containing Co as the main component, such as rPtTi, CoCrTa, and CoNiCr, can be used, in order to obtain a high coercive force suitable for high recording density, it is particularly preferable to use a Co alloy containing Pt. preferable.

A 5 to 30 nm carbon layer is formed as a protective film on the magnetic layer, and a perfluoroalkylpolyether type lubrication layer is formed.
By providing ~ 30 nm, a highly reliable magnetic recording medium can be obtained. By using hydrogen-added carbon, silicon carbide, tungsten carbide, or a mixed film of these compounds and carbon as the protective film, sliding resistance and corrosion resistance can be improved.

Further, in a magnetic recording medium using a glass substrate, it is desirable to form an orientation control layer such as Ta between the underlayer and the substrate in order to orient the (100) CrB alloy underlayer. Furthermore, by forming a metal such as Ti, Zr, or Cr, or an oxide thereof between the orientation control layer and the glass substrate, the adhesion with the glass is improved, and the adsorption gas on the substrate or from the glass Diffusion of impurity ions in the film into the film is suppressed, and good magnetic properties are obtained. It is also possible to form an underlayer made of a low melting point metal such as Al or Ag, or an alloy thereof. As a result, fine irregularities are formed on the medium surface, and CSS (contact start stop) characteristics can be improved.

The distance between the two soft magnetic shield layers sandwiching the resistance sensor portion of the magnetoresistive head for reproduction used in the magnetic memory device of the present invention is 0.35 μm or less. The shield layer spacing is
When it is 0.35 μm or more, the resolution is lowered, which is not preferable.
The medium has a coercive force of 2 kOersted or more, and the product of the magnetic layer thickness t and the residual magnetic flux density Br, Br × t, is in the range of 10 to 130 gauss-microns. Higher recording density (150kFCl or more) when the coercive force is smaller than 1.8 kilo Oersted
It is not preferable because the output at is small. Also, Br × t is 130
When it is larger than Gauss-micron, the resolution decreases and
If it is smaller than Gauss-micron, the output becomes too small, so sufficient recording / reproducing characteristics cannot be obtained when high density recording of 2 gigabits per parallel inch is performed.

Further, in the magnetoresistive effect magnetic head, a plurality of conductive magnetic layers that cause a large resistance change when their magnetization directions are relatively changed by an external magnetic field and a conductive magnetic layer disposed between the conductive magnetic layers are provided. By using a magnetoresistive sensor including a magnetic non-magnetic layer and utilizing the giant magnetoresistive effect or spin valve effect, the signal strength can be further increased, and a recording density of 3 gigabits or more per square inch can be achieved. It is possible to realize a highly reliable magnetic storage device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows Br × t, standardized medium noise, and device S / N.
2 is a diagram showing the relationship between the concentration of B added in the underlayer and the normalized medium noise, and FIG. 3 is a diagram showing
FIGS. 4A and 4B are respectively a schematic plan view and a sectional view taken along the line AA ′ of the magnetic memory device according to one embodiment of the present invention. FIG. 4 shows the magnetic memory device according to the present invention. FIG. 5 is a perspective view showing an example of a sectional structure of the head, and FIG.
FIG. 6 is a schematic diagram showing an example of a sectional structure of a magnetoresistive sensor portion of a magnetic head in a magnetic memory device of the present invention, and FIG. 6 is a sectional view of a medium used in an example of the present invention,
FIG. 8 is a diagram showing the relationship between coercive force and overwriting characteristics in the media of the examples of the present invention and comparative examples, and FIG. 8 is an example of the cross-sectional structure of the magnetic head in the magnetic memory device of the present invention. It is a perspective view shown.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1: An embodiment of the present invention will be described with reference to FIGS. 3, 4, and 5. FIG. 3 is a schematic plan view and a schematic cross-sectional view of the magnetic storage device of this embodiment.
It shows in (a) and FIG.3 (b). This device is a magnetic head
1, and its driving unit 2, a recording / reproducing signal processing unit 3 of the magnetic head, a magnetic recording medium 4, and a driving unit 5 for rotating the magnetic recording medium 4.
It is a magnetic storage device having a well-known structure consisting of.

The structure of the above magnetic head is shown in FIG. This magnetic head is a composite type head having both an electromagnetic induction type magnetic head for recording and a magnetoresistive effect type magnetic head for reproduction formed on a substrate 6. The recording head comprises an upper recording magnetic pole 8 sandwiching the coil 7 and a lower recording magnetic pole / upper shield layer 9, and the gap layer thickness between the recording magnetic poles is 0.3 μm. In addition, Cu with a thickness of 3 μm was used for the coil. The reproducing head comprises a magnetoresistive sensor 10 and electrode patterns 11 on both ends thereof, and the magnetoresistive sensor is sandwiched between a lower recording magnetic pole / upper shield layer and a lower shield layer 12 each having a thickness of 1 μm, and the shield interlayer distance is 0.25 μm. Is. In FIG. 4, the gap layer between the recording magnetic poles and the gap layer between the shield layer and the magnetoresistive sensor are omitted.

FIG. 5 shows a sectional structure of the magnetoresistive sensor. The signal detection area 13 of the magnetic sensor is composed of a portion in which a lateral bias layer 15, a separation layer 16 and a magnetoresistive ferromagnetic layer 17 are sequentially formed on a gap layer 14 of oxidized A1. A 20 nm NiFe alloy was used for the magnetoresistive ferromagnetic layer. Although 25 nm of NiFeNb was used for the lateral bias layer, any ferromagnetic alloy such as NiFeRh having a relatively high electric resistance and good soft magnetic characteristics may be used. The lateral bias layer is magnetized in the in-plane direction (horizontal direction) perpendicular to the current by the magnetic field generated by the sense current flowing through the magnetoresistive ferromagnetic layer, and applies a lateral bias magnetic field to the magnetoresistive ferromagnetic layer. As a result, a magnetic sensor having a linear reproduction output with respect to the leakage magnetic field from the medium can be obtained. The separation layer that prevents the shunting of the sense current from the magnetoresistive ferromagnetic layer was made of Ta, which has a relatively high electric resistance, and its thickness was 5 nm.

At both ends of the signal detection area, there are tapered portions 18 processed into a tapered shape. The taper portion is composed of a permanent magnet layer 19 for making the magnetoresistive ferromagnetic layer into a single magnetic domain, and a pair of electrodes 11 for taking out signals formed thereon. The permanent magnet layer must have a large coercive force and the magnetization direction must not change easily, and CoCr, CoCrPt alloys, etc. are used.

FIG. 6 shows the film structure of the magnetic recording medium used in this example. An underlayer 21, a magnetic layer 22, a protective film 23, and a lubricating film 24 are formed in this order on a nonmagnetic substrate 20. Here, the underlayer formed between the non-magnetic substrate and the magnetic layer is described as a single layer, but it includes both a single layer and a multilayer. The substrate used was a chemically strengthened soda lime glass washed with an alkaline detergent and then spin dried. The first underlayer, whose main purpose is to prevent the invasion of ions and adsorbed gas from the glass on the substrate and to achieve good adhesion with the glass.
Second underlayer mainly for (100) orientation of CrB alloy, third underlayer composed of CrB alloy layer mainly for (11.0) orientation of Co magnetic layer, Co alloy magnetic layer The carbon protective film 24 is formed. The first underlayer is 50 nm Zr, the second underlayer is 10 nm Ta, and the third underlayer is 30 nm Cr-1.
Cr-14.3at% Ti-5at which added 5at% of B to 5at% Ti alloy
% Alloy, Co-20at% Cr-12at% Pt alloy for the magnetic layer, and carbon for the protective film, these were continuously formed in vacuum. All layers were formed by DC sputtering at a deposition rate of 5-8 nm / sec under an argon gas pressure of 5 mTorr. The substrate was heated so that the substrate temperature was 300 ° C after the second underlayer Ta was formed. A perfluoroalkylpolyether-based material diluted with a fluorocarbon material was applied as a lubricant to the formed medium. Also,
A Cr-15at% Ti alloy containing no B was used for the third underlayer, and a medium having a coercive force similar to that of the medium of the present example was produced.
This was used as a comparative example.

The coercive force of the medium of this example was 2900 Oe and Br × t was 82 gauss microns. When incorporated into the above magnetic storage device together with the medium of the comparative example, the head flying height was 30 nm and the linear recording density was 210 kBP.
Recording and reproduction were evaluated at I and track density of 9.6 kTPI. When the medium of this example was used, the standardized medium noise was reduced by about 20% and the overwriting characteristic was improved by about 10 dB compared with the case of using the medium of the comparative example. Therefore, 2 per square inch
Good recording and reproducing characteristics were obtained for gigabit recording density. From the above, it was found that adding B to the underlayer is effective in reducing medium noise and improving overwrite characteristics. Second Embodiment In a magnetic storage device having the same configuration as the first embodiment,
2.5 inch diameter, 0.635 mm pressure plated NiP on the substrate surface
A magnetic recording medium formed on an A1 alloy substrate (hereinafter referred to as NiP / A1 substrate) was used.

After heating the NiP / Al alloy substrate textured in the circumferential direction to 300 ° C, Cr-9at% Ti-5at% B alloy was applied.
10-30 nm, CoCrPt alloy 20 nm, and carbon protective film 10 nm were formed continuously. At this time, the argon gas pressure during formation of the magnetic layer was changed to 5 to 15 mTorr. Br x of these media
t was in the range of 70 to 90 gauss microns. Also,
These media have magnetic anisotropy in the circumferential direction due to the texture processing of the substrate. Therefore, the coercive force in the circumferential direction is larger than that in the radial direction, and the ratio, that is, the orientation ratio is 1.4 to 1.6.
Met. As a result, the magnetization direction is stabilized in the recording direction, and good recording characteristics are obtained.

Using these media, recording / reproducing characteristics were evaluated under the same conditions as in Example 1. The relationship between coercive force and overwriting characteristics is shown in FIG. In the same figure, the results of a medium manufactured by the same process as the above medium using a Cr-15at% Ti underlayer without addition of B are also shown as a comparative example. When comparing media with similar coercive force, the overwrite characteristics are Cr-9at% Ti-5at%
The B underlayer medium is improved by about 15 dB, indicating that the addition of B to the underlayer improves the overwriting characteristics.
Other recording / reproducing characteristics were also very good for a recording density of 2 gigabits per square inch.

As a result of X-ray diffraction measurement, the CrTiB underlayer had a bcc structure and had a strong (100) orientation.
It was found that the t magnetic layer was also strongly (11.0) oriented by epitaxial growth. This orientation is Cr without addition of B
This is the same as when the Ti underlayer is used. In other words, it was found that the addition of B does not change the orientation of the underlayer, so that the (11.0) orientation of the CoCrPt magnetic layer, which provides good magnetic properties, does not collapse.

Example 3: An example of a magnetic memory device having the same configuration as that of Example 1 but different in the resistance sensor of the reproducing head and the film configuration of the recording medium is shown below.

As shown in FIG. 8, the resistance sensor has a Ta buffer layer 25 of 5 nm and 7 nm for forming the (111) orientation of the magnetic layer on the oxidized Al gap layer 14 and a first magnetic layer 26 of 1.5 nm and Cu of 1.5 nm. Middle layer 27,3n
2nd magnetic layer of m 28,10nm Fe-50at% Mn antiferromagnetic alloy layer
29 is a structure formed sequentially. In the first magnetic layer
A Ni-20at% Fe alloy was used, and Co was used for the second magnetic layer. The magnetization of the second magnetic layer is fixed in one direction by the exchange magnetic field from the antiferromagnetic layer. On the other hand, the direction of magnetization of the first magnetic layer, which is in contact with the second magnetic layer via the non-magnetic layer, changes due to the leakage magnetic field from the magnetic recording medium, resulting in a resistance change. Such a resistance change caused by a change in the relative directions of the magnetizations of the two magnetic layers is called a spin valve effect. In the present embodiment, a spin valve type magnetic head utilizing this effect was used as a reproducing head. The taper portion has the same structure as the magnetic sensor of the first embodiment.

The film forming process of the recording medium used in this example is described below. The textured NiP / Al substrate was heated to 260 ° C by lamp heating, and then the first underlayer Cr was 20 nm and the second underlayer CrB alloy was 30 nm by DC sputtering.
After that, a CoCrPt magnetic layer was continuously formed with a 25 nm and 10 nm carbon protective film. Cr of the first underlayer plays a role of orientation control that causes the second underlayer to have a bcc (100) orientation. The second underlayer CrB alloy contains Cr-14.3 at% Ti-5 at% B
Alloy, Cr-14.3at% V-5at% B Alloy, Cr-14.3at% Mo-5
At% B alloy was used. In addition, Cr-15at% Ti without B addition
Alloys, Cr-15 at% V alloys, and Cr-15 at% Mo alloys were also prepared as media for the second underlayer and used as comparative examples.

After applying the lubricant, it was incorporated into a magnetic memory device using the magnetoresistive sensor, and recording / reproducing evaluation was performed under the same conditions as in Example 1. The results are shown in Table 1. When the medium of the present example is used, the normalized medium noise is reduced by 10% or more and the overwriting characteristic is improved in any case as compared with the comparative example. Therefore, good recording and reproducing characteristics were obtained for a recording density of 2 gigabits per square inch.

In addition, among the media of this example, the CrTiB underlayer medium had particularly low standardized medium noise, and the CrVB underlayer medium exhibited the best overwriting characteristics.

Example 4 In the same magnetic storage device as in Example 1, Cr-14.3 at% Ti-5 at% -B alloy, Cr-14.3 at the underlayer of the magnetic recording medium.
At% Ti-5at% -C alloy, Cr-14.3at% Ti-5at% -P alloy, and Cr-14.3at% Ti-5at% -Bi alloy were used.

After heating the NiP / Al substrate to 250 ℃, apply 30n of each of the above underlayers.
The m, CoCrPTa magnetic layer was formed to 20 nm, and the carbon protective film was formed to 10 nm. After applying the lubricant, the recording / reproducing characteristics were evaluated under the same conditions as in Example 1. A medium using a 30 nm CrTi alloy for the underlayer was prepared and evaluated under the same conditions, and this was used as a comparative example.

The underlayer of the medium of this embodiment has a bcc structure (100).
The magnetic layer is oriented (1
1.0) Orientation. Table 2 shows the recording / reproducing characteristics of the mediums of this example and the comparative example. As compared with the comparative example, the media of the present examples all had reduced medium noise and improved overwriting characteristics, and had good recording / reproducing characteristics for a recording density of 2 gigabits per square inch. The normalized media noise is particularly low in the media of CrTiB underlayer and CrTiP underlayer, and it is clear that adding B and P is effective for reducing noise. Also,
In the CrTiC underlayer medium, the hcp (11.0) orientation of the magnetic layer is the strongest, and high coercive force and S * are obtained. Further, the CrTiBi underlayer medium had better corrosion resistance than the other Examples.
When the CSS test was performed on the medium of this example, the friction coefficient was 0.3 or less, which was a good value even after CSS was performed 30,000 times.

Example 5 A first underlayer Cr-13.5 at% Ti-10 at% -B was formed on the same tempered glass substrate as in Example 1 by DC sputtering.
After forming 10 nm, the substrate is heated to 200 ℃, the second underlayer Cr-10at% Ti alloy 30nm is formed, CoCrPt magnetic layer 25nm,
A carbon protective film was continuously formed with a thickness of 10 nm.

When the X-ray diffraction was measured, only the bcc (200) peak which seems to be that of the underlayer and the hcp (11.0) peak from the CoCrPt alloy layer were observed in the diffraction pattern. Cr-13.5at% Ti-10at% -B alloy of the first underlayer and Cr of the second underlayer
Since the lattice constant of -at% 10Ti alloy is very close,
It is difficult to determine which the (200) peak is from. Therefore, a 10 nm CrTiB single layer film was formed under the same conditions as when forming the medium, and the X-ray diffraction was measured. Since no clear peak was found in the obtained diffraction pattern, b
The cc (200) peak appears to be from the second underlayer CrTi alloy. From this, it is clear that the CrTiB alloy of the first underlayer has an amorphous structure or a fine crystal structure close to it, and the CrTi layer formed thereon has a (100) orientation. Therefore, the Co alloy magnetic layer grows epitaxially and has a (11.0) orientation. In addition, the CrTiB layer of the first underlayer has a strong bcc (110) orientation at a film thickness of 30 nm or more.
Ti also has a (110) orientation, and the CoCrPt alloy layer has a (10.1) orientation. The (10.1) -oriented CoCrPt layer is not preferable because the in-plane component of the c-axis, which is the easy axis of magnetization, is reduced as compared with the case of (11.0) orientation, and the magnetic properties are deteriorated.

The coercive force of the medium with the first underlayer film thickness of 10 nm was 2480 Oersted. When this was incorporated into a magnetic storage device similar to that of Example 3 and the recording / reproducing characteristics were evaluated, it was 45 dB.
The overwriting characteristics of were obtained. After the head seek test 50,000 times from the inner circumference to the outer circumference, the number of bit errors was 10 bits / surface or less, and the MTBF was 150,000 hours.

Although the film formation in this embodiment was all performed by the DC sputtering method, it is easily expected that the same effect can be obtained by using the RF sputtering method, the ion beam sputtering method, the ECR sputtering method, or the like.

INDUSTRIAL APPLICABILITY The magnetic recording medium of the present invention has a medium noise reduced by 10 to 20% as compared with the conventional magnetic recording medium, and the overwriting characteristic is further improved by about 15 dB. A magnetic storage device that combines this medium with a magnetoresistive head achieves high S / N and low bit error rate, and achieves an average failure interval of 150,000 hours or more at a high recording density of 2 gigabits per square inch. it can.

Therefore, according to the present invention, it is possible to provide a highly reliable magnetic storage device capable of recording and reproducing high-density information, and it is possible to meet the demand for larger capacity of the magnetic storage device.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Ishikawa 5-16-3-3, Kamimizumoto-cho, Kodaira-shi, Tokyo (72) Inventor Ken Tanabashi 5977-1, Tsujido, Fujisawa-shi, Kanagawa Hitachi Seaside. Domito (72) Inventor Yoshifumi Matsuda 2278, Kokuzu, Odawara, Kanagawa No. 2 Green Heights 202 (72) Inventor Tomio Yamamoto 2-32 Koyasu, Hachioji, Tokyo Hitachi Koyasudai D-303 (56) Reference Japanese Patent Laid-Open No. 7-37237 (JP, A) Japanese Patent Laid-Open No. 7-262546 (JP, A) Japanese Patent Laid-Open No. 7-307020 (JP, A) Japanese Patent Laid-Open No. 7-73441 (JP, A) Japanese Patent Laid-Open No. 7-73433 (JP , A) JP-A-7-43427 (JP, A) JP-A-6-215348 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 5 / 62-5 / 858

Claims (5)

(57) [Claims] 1. A magnetic recording medium having a magnetic layer formed on a substrate through a single layer or a plurality of underlayers, wherein at least one of the single underlayer or the plurality of underlayers contains Cr as a main component. Alloy material containing at least one element selected from the first group consisting of B, C, P and Bi and containing at least one element selected from the second group consisting of B, C, P and Bi A magnetic recording medium comprising: 2. The underlayer containing Cr as a main component is substantially
The magnetic recording medium according to claim 1, comprising Cr, Ti, and B. 3. The concentration of at least one element selected from the second group contained in the underlayer containing Cr as a main component,
The magnetic recording medium according to claim 1, wherein the content is 1 at% or more and 20 at% or less. 4. A magnetic recording medium having a magnetic layer formed on a substrate through a single layer or a plurality of underlayers, a drive section for driving the magnetic layer in a recording direction, and a magnetic head comprising a recording section and a reproducing section. A magnetic storage device having means for moving the magnetic head relative to the magnetic recording medium, and recording / reproducing signal means for performing signal input of the magnetic head and reproduction of an output signal from the magnetic head, The reproducing portion of the magnetic head is composed of a magnetoresistive effect magnetic head, and at least one of a single underlayer or a plurality of underlayers of the magnetic recording medium contains Cr as a main component, and T
From an alloy material containing at least one element selected from the first group consisting of i and V and containing at least one element selected from the second group consisting of B, C, P and Bi A magnetic storage device characterized by the following. 5. The underlayer containing Cr as a main component is substantially
The magnetic storage device according to claim 4, wherein the magnetic storage device comprises Cr, Ti, and B.