JP2000187825A - Magnetic recording medium and magnetic storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a medium low in noise and suppressed in thermomagnetic relaxation by making a magnetic layer made of an alloy consisting essentially of Co and having a hexagonal dense structure and continuously, step by step or periodically changing the composition of at least one kind of metallic element components contained in the magnetic layer in the vertical direction to a substrate. SOLUTION: The magnetic layer is formed on the substrate, the magnetic layer is an alloy film consisting essentially of Co, containing Cr and having the hexagonal dense structure and the concentration of one of the metallic elements of Co and Cr is changed in the film thickness direction. A magnetic resistance sensor part of a magnetic head is formed from one, which is composed of plural conductive magentic layers producing large resistance change by relatively changing respective magnetization direction by the outside magnetic field and a conductive non-magnetic layer arranged between the conductive magnetic layers and utilizes spin valve effect. In such a case, the gap between 2 pieces of shield layers interposing the resistance sensor part is preferably <=0.25 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic storage device, specifically, a magnetic storage device having a recording density of 8 gigabits per square inch or more, and a high-power, low-noise, and thermal storage device for realizing the same. The present invention relates to a thin-film magnetic recording medium having high stability in which reproduction output attenuation due to magnetic relaxation is suppressed.

[0002]

2. Description of the Related Art In recent years, with the increase in the capacity of magnetic storage devices,
Magnetic recording media are required to have higher densities. Increasing the coercive force and lowering the noise are inevitable in increasing the density of the medium. For this purpose, the crystallinity and orientation of the magnetic layer must be improved.
It is necessary to reduce the size of the magnetic crystal grains. For the magnetic layer, a Co alloy having a hexagonal close-packed structure is used.However, in the case of an in-plane magnetic recording medium, the (11.0) plane of the magnetic layer has It is desirable to take an orientation parallel to the substrate (hereinafter referred to as (11.0) orientation). Co
Since the (11.0) plane of the alloy has good lattice matching with the (100) plane of a Cr alloy having a body-centered cubic structure, a (100) -oriented Cr alloy is used as the underlayer. As a result, the magnetic layer grows epitaxially and a (11.0) orientation is obtained.However, since this is a heteroepitaxial growth, which grows on crystals having different crystal structures, the crystallinity is deteriorated in the initial growth layer of the magnetic layer, and the magnetic layer is sufficiently grown. Good orientation and crystallinity of the magnetic layer were not obtained. Also, even when formed on an underlayer having the same crystal structure, such as a vertically oriented Co alloy magnetic layer formed on a Ti underlayer, if the elements are different, the crystallinity in the initial growth layer is low. Disturbance and insufficient magnetic properties cannot be obtained. As a countermeasure against this, there has been proposed a method of forming a nonmagnetic intermediate layer containing Co as a main component and having the same hexagonal close-packed structure as the magnetic layer between the magnetic layer and the underlayer (Japanese Patent Application Laid-Open No. 55-122232, Kaiping 1
0-233014, JP-A-10-233016). Since the magnetic crystal grows almost continuously on crystal grains in the intermediate layer, good crystal growth occurs from the initial growth stage, and both crystallinity and orientation are improved, and good magnetic properties are obtained. On the other hand, in recent years, in order to reduce noise, further miniaturization of magnetic crystal grains and thinning of the magnetic film thickness have been advanced, but this has caused a serious thermomagnetic relaxation phenomenon in which the recording magnetization is attenuated with time. I have. This is considered to be due to the fact that the influence of thermal disturbance is extremely strong due to the miniaturization and thinning of the magnetic grains, and the ratio of ultrafine magnetic grains that easily cause magnetization reversal increases. The ultrafine grains, which are a major factor causing thermomagnetic relaxation, are present in a large amount in the initial growth region of the magnetic layer, and thus the region is demagnetized. It is effective in a sense.

However, since the intermediate layer and the magnetic layer are formed using different cathodes, contamination of the surface of the intermediate layer occurs due to residual impurity gas in the chamber during the transfer of the substrate after the formation of the intermediate layer and before the formation of the magnetic layer. . Therefore, the continuity of crystal grains from the intermediate layer to the magnetic layer is not sufficient. Therefore, fine crystal grains still exist in the initial growth layer of the magnetic layer, which causes thermomagnetic relaxation with further miniaturization of the magnetic crystal grains and thinning of the magnetic film thickness. In order to realize a high-density magnetic recording medium, it is necessary to eliminate such ultra-fine magnetic grains and achieve both reduction of medium noise and suppression of thermal magnetic relaxation.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic layer with a composition modulation in a direction perpendicular to a substrate.
An object of the present invention is to provide a magnetic recording medium in which the crystallinity of a magnetic layer is improved, and at the same time, fine magnetic grains in an initial growth layer are demagnetized to reduce noise and suppress thermomagnetic relaxation. By optimizing the conditions in combination with a highly sensitive spin valve magnetic head, a highly reliable magnetic storage device having a recording density of 8 gigabits per square inch or more can be provided.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a magnetic recording medium comprising:
Is composed of an alloy having a hexagonal close-packed structure whose main component is a composition of at least one elemental metal component contained in the magnetic layer,
A magnetic recording medium characterized by changing continuously, stepwise, or periodically with respect to a direction perpendicular to the substrate, a drive unit for driving the magnetic recording medium in the recording direction, and a magnetic unit comprising a recording unit and a reproducing unit A magnetic storage device comprising: a head; a unit for moving the magnetic head relative to the magnetic recording medium; and a recording / reproducing signal processing unit for performing signal input to the magnetic head and reproduction of an output signal from the magnetic head. Is achieved by a magnetic storage device in which a reproducing section of the magnetic head is constituted by a magnetoresistive magnetic head. The magnetic resistance sensor portion of the magnetic head used in the magnetic recording device, a plurality of conductive magnetic layers that cause a large resistance change by the relative change of the magnetization direction by an external magnetic field,
It is assumed that a spin valve effect constituted by a conductive non-magnetic layer disposed between the conductive magnetic layers is used. The distance between the two shield layers sandwiching the resistance sensor section (shield distance) is preferably 0.25 μm or less. This is because when the shield interval is 0.25 μm or more, the resolution is reduced, and the phase jitter of the signal is increased.

[0006] The medium is formed by a so-called multiple simultaneous sputtering method using a film forming apparatus having a structure in which sputtered particles are simultaneously incident on a substrate from a plurality of cathodes. By changing the input power at the time of discharge of each cathode continuously or stepwise with time, it is possible to change the film formation rate and to impart composition modulation in the film thickness direction.
The region of the magnetic layer on the substrate side with a thickness of 5 nm to about 20 nm,
When demagnetization is performed by increasing the Cr concentration, fine magnetic crystal grains in the region are demagnetized, and thermomagnetic relaxation is suppressed. Since the diameter of the fine crystal grains is about 5 to 10 nm, the thickness of the nonmagnetic region needs to be 5 nm or more. On the other hand, if the thickness exceeds 20 nm, the magnetic crystal grains are enlarged, and the medium noise is increased, which is not desirable. When the Cr concentration is 26 at% or less, magnetization occurs, and when the Cr concentration is 45 at% or more, the hexagonal dense structure is broken. Therefore, the Cr concentration in the nonmagnetic region is preferably 26 at% or more and 45 at% or less. Within this concentration range, the Cr concentration may be constant in the film thickness direction or may have a concentration gradient. When the magnetic layer contains high concentrations of Pt and Ta, the lattice constant changes continuously by giving a concentration gradient such that the element concentration is low on the underlayer side and increases in the film thickness direction. Can be done. As a result, high Pt and high Ta concentration can be achieved without deteriorating the lattice matching at the interface between the magnetic layer and the underlayer, so that a medium with high coercive force and suppressed thermomagnetic relaxation can be obtained. Further, the magnetic layer may have a structure in which the magnetic layer is divided in the thickness direction in the high Cr concentration region. In this case, high Cr
The concentration region may be non-magnetic or have some magnetization. If it is non-magnetic, the effective number of magnetic crystal grains in one bit increases, as in a multilayer magnetic layer medium in which the magnetic layer is divided by a non-magnetic intermediate layer, so that medium noise is reduced.
However, since the magnetic layer is a single-layer film formed continuously, there is no contamination of the interface by an impurity gas as in a multilayer magnetic layer divided by an intermediate layer, and good crystallinity can be obtained.
When the high Cr region is slightly magnetized, medium noise slightly increases, but thermomagnetic relaxation is suppressed. this is,
This is because leaving a slight interaction between the divided magnetic layers increases the magnetization reversal volume as compared with the case where there is no interaction, and is particularly effective when the magnetic layer is thin.
The composition modulation described in the present invention relates to the main metal element contained in the magnetic layer. For example, the composition modulation described inevitably or intentionally occurs at the interface between the underlayer and the magnetic layer. Layers and the like and the concentration gradient caused by their diffusion are not included in the present invention. Further, the case where the alkali metal in the ion-enhanced layer of the tempered glass substrate, the residual cleaning agent adhered to the substrate surface, and the like diffuse and have a concentration gradient in the film thickness direction is also outside the scope of the present invention. The effect described in the present invention is effective for a medium having magnetic anisotropy in both the in-plane direction and the perpendicular direction, and the direction of the axis of easy magnetization is not particularly limited.

In the in-plane magnetic anisotropic medium, an alloy mainly containing an element having a body-centered cubic structure such as Cr is used for the underlayer. The base alloy may contain additional elements such as Ti, Mo, and V for the purpose of reducing the particle size and improving the lattice constant. Further, the additive element can have a gradient in the film thickness direction. If the concentration of the additive element on the substrate side is reduced and the concentration is increased toward the magnetic layer side, the underlayer crystal grows well at the initial stage, and the crystallinity and orientation are good, and the lattice constant on the surface is large. Is obtained. This makes it possible to improve the crystallinity and orientation of the underlayer and reduce lattice misfit at the interface of the magnetic layer. For the perpendicular magnetic anisotropic medium, an underlayer such as Ti can be used. Also in this case, the same effect as that of the in-plane magnetic anisotropic medium can be obtained by providing the concentration gradient. Further, a layer for the purpose of controlling the structure of the underlayer, improving the adhesion, and the like may be formed between the substrate and the underlayer to form a multilayer underlayer.

As the substrate, a chemically strengthened glass substrate, a crystallized glass substrate, an amorphous carbon substrate, or the like can be used in addition to an Ni—Pg-plated Al—Mg alloy substrate. By forming carbon as a protective layer of the magnetic layer with a thickness of 3 nm to 20 nm and a lubricating layer of adsorbent perfluoroalkyl polyether etc. with a thickness of 2 nm to 10 nm, high reliability and high density recording are possible. A recording medium is obtained. As the protective layer, a carbon film to which hydrogen or nitrogen is added, or a film made of a compound such as silicon carbide, tungsten carbide, (W-Mo) -C, (Zr-Nb) -N, or a combination of these compounds A mixed film of carbon may be used.

The magnetic properties of the medium are as follows: the coercive force measured in the easy axis direction is 2600 Oe or more, and the product Br × t of the residual magnetic flux density Br and the film thickness t is 40 Gauss / micron or more and 100 Gauss / micron or less. This is preferable because good recording / reproducing characteristics can be obtained in a recording density region of 8 gigabits per square inch or more. If the coercive force in the circumferential direction is smaller than 2600 Oe, the output at a high recording density (300 kFCI or more) becomes small, which is not preferable. Also, when Br × t is larger than 100 Gauss / micron, the resolution is reduced, and when it is smaller than 40 Gauss / micron, the reproduction output is undesirably reduced.

[0010]

<Embodiment 1> An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. FIGS. 1 (a) and 1 (b) are a schematic plan view and a schematic sectional view of the magnetic storage device of this embodiment.
Shown in This device comprises a magnetic head 11 and its driving unit 12
And a recording / reproducing signal processing means 13 for the magnetic head, a magnetic recording medium 14, and a drive unit 15 for rotating the magnetic recording medium, which has a known structure.

FIG. 2 shows the structure of the magnetic head. This magnetic head is a composite type head having both an electromagnetic induction type magnetic head for recording and a spin valve type magnetic head for reproduction formed on the base 21. The recording head is a coil 22
Upper write pole 23 and lower write pole and upper shield layer sandwiching
The gap layer thickness between the recording magnetic poles was set to 0.3 μm. Cu having a thickness of 3 μm was used for the coil. The reproducing head includes a magnetoresistive sensor 25 and electrode patterns 26 at both ends thereof.
Each of the magnetoresistive sensors is sandwiched between a lower recording magnetic pole / upper shield layer 1 μm thick and a lower shield layer 27, and the distance between the shield layers is 0.22 μm. In FIG. 2, the gap layer between the recording magnetic poles and the gap layer between the shield layer and the magnetoresistive sensor are omitted.

FIG. 3 shows a sectional structure of the magnetoresistive sensor.
The signal detection region 31 of the sensor has a Ta buffer layer 33 of 5 nm, a first magnetic layer 34 of 7 nm, 1.5 n on the gap layer 32 of Al oxide.
m Cu intermediate layer 35, 3 nm second magnetic layer 36, 10 nm Fe-50at%
It has a structure in which Mn antiferromagnetic alloy layers 37 are sequentially formed. For the first magnetic layer, a Ni-20at% Fe alloy was used, and for the second magnetic layer, Co was used. 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, so that a resistance change occurs. As a reproducing head, a spin-valve magnetic head utilizing a resistance change accompanying a change in the relative direction of the magnetization of the two magnetic layers was used. At both ends of the signal detection region, there are tapered portions 38 which are processed into a tapered shape. The tapered portion includes a permanent magnet layer 39 for converting the magnetoresistive ferromagnetic layer into a single magnetic domain, and a pair of electrodes 11 formed thereon for extracting a signal. The permanent magnet layer needs to have a large coercive force and the magnetization direction does not easily change, and CoCr, CoCrPt alloy, or the like is used.

FIG. 4 shows the layer structure of the magnetic recording medium of the present invention. Heat the Ni-plated Al substrate 41 to 250 ° C
A -30 at% Mo underlayer 42 was formed in order of 30 nm, a CoCrPt magnetic layer 43 was formed in 30 nm, and a carbon protective film 44 was formed in order of 8 nm. The magnetic layer was formed by a simultaneous sputtering method in which the Co, Cr, and Pt targets 52 were independently discharged by a film forming apparatus having a plurality of cathodes 51 as shown in FIG. It should be noted that the figure schematically shows the arrangement of the cathodes, and the transport mechanism and the like are omitted. By varying the input power of each cathode with time, the composition was modulated in the film thickness direction. All films are 10mTor
The process was performed in a pure Ar atmosphere of r, and the substrate 53 was rotated at 20 rpm by the substrate rotation drive unit 54. As a comparative example, Cr-30
After the formation of the at% Mo underlayer, a 10 nm Co-35at% Cr intermediate film is sandwiched between the Co-2
A medium in which a 1 at% Cr-10 at% Pt alloy magnetic layer was formed to a thickness of 15 nm was manufactured.

FIG. 6 schematically shows a film thickness profile of each element in the magnetic layer obtained by the secondary ion mass spectrometry for the medium of the present embodiment. The Cr concentration is constant at 30 at% from the underlayer surface up to 15 nm in the film thickness direction, but 21 a
t%. Therefore, it is considered that the magnetic layer region within a distance of about 15 nm from the underlayer interface in the thickness direction is demagnetized due to the high Cr concentration. In addition, the Pt concentration continuously increases from the surface of the underlayer to 15 nm in the film thickness direction.
It is constant at 10at%. On the other hand, in the comparative example medium, the concentration of each element in the magnetic layer was all constant in the film thickness direction. Further, in the oxygen concentration profile, in the example medium, only on the surface of the underlayer and the magnetic surface. Although a peak of the concentration was observed, a peak was also observed at the interface between the intermediate layer and the magnetic layer in the medium of the comparative example in addition to the above. The absolute value of the peak intensity between the intermediate magnetic layers was about 200 cps, which was about twice the absolute value of the oxygen intensity inside the magnetic layer (70 to 90 cps). This is probably because the interface between the layers was contaminated by the residual oxygen gas in the chamber during the transfer of the substrate. When the X-ray diffraction measurement was performed on the medium of this example and the medium of the comparative example, the diffraction peak from the magnetic layer was hcp (1
1.0) Only the peak, and the half width of the rockin curve of the peak was 1.8 ° in the example medium, but was 4.2 ° in the comparative example medium. This indicates that better crystallinity was obtained in the example medium.

Table 1 shows the coercive force, normalized medium noise, and reproduction output attenuation rate of the medium of this embodiment and the medium of the comparative example.

[0016]

[Table 1]

Here, the normalized medium noise is a value obtained by standardizing the medium noise when recording at a linear recording density of 300 kFCI by the signal strength of the isolated reproduction wave and the track width. Also,
The reproduction output attenuation factor is the reproduction output E0 of a signal recorded at a linear recording density of 300 kFCI immediately after recording, and the reproduction output 72 hours later.
Using E72h, the value is defined as (E0-E72h) / E0. Hereinafter, the values defined in this way are used as the normalized medium noise and the reproduction output attenuation rate. In both media,
Although the medium noise is almost the same, the medium of the embodiment has a coercive force,
Output decay rate is low. Therefore, it was found that by imparting the composition modulation in the thickness direction of the magnetic layer, the in-plane orientation and the crystallinity of the c-axis were improved, the coercive force was improved, and the thermomagnetic relaxation was suppressed.

After applying the lubricant 45 to the medium of the present embodiment,
The recording / reproducing characteristics were evaluated under the conditions of 8 gigabits per square inch together with the above magnetic head in a magnetic storage device. As a result, a high device S / N of 2.1 was obtained. Contact start / stop test (CSS test)
, The coefficient of friction was 0.2 or less even after 30,000 times of CSS.

Example 2 After forming a Cr seed layer at a room temperature of 20 nm on a chemically strengthened glass substrate, the Cr seed layer was heated to 220 ° C. by a lamp heater, and a Cr-20at% Ti underlayer was formed at a thickness of 30 nm.
An oCrPtTa magnetic layer was formed with a thickness of 14 nm, and a carbon protective film was formed with a thickness of 6 nm. The magnetic layer was formed by a simultaneous sputtering method using a Co-2at% Ta alloy, Cr, and a Pt target. The magnetic layer region above the initial growth layer has a width of about 3 nm and a maximum Cr concentration of 30a.
Cutting was performed in the high Cr concentration region of t%. Each of the divided magnetic layers has a thickness of about 9 nm. Further, the medium up to the underlayer has the same structure as the above medium, and the magnetic layer has a two-layer structure of a 10 nm Co-19at% Cr-8at% Pt alloy sandwiching a 3 nm Co-30at% Cr alloy intermediate layer. It was produced as a comparative example. In this example, in order to compare the effect on thermal demagnetization, the magnetic film thickness was intentionally made thin so that thermal demagnetization was easy.

This medium is referred to as Example 2-1. FIG. 8 schematically shows the film thickness profile of Co, Cr, and Pt in the magnetic layer obtained by secondary ion mass spectrometry for the medium of Example 2-1. Regarding the oxygen concentration, in the medium of Example 2-1, the inside of the magnetic layer was almost constant except for the interface, whereas in the medium of the comparative example, the oxygen concentration in the magnetic layer was 1.5 to A concentration peak of about twice was observed. this is,
It is believed that before and after the formation of the intermediate layer, it was contaminated by residual gas in the chamber. Table 2 shows the magnetic characteristics and the normalized medium noise of both.

[0021]

[Table 2]

The medium of Example 2-1 has lower noise and lower reproduction output decay rate than the medium of the comparative example. On the other hand, in the above embodiment, the maximum Cr concentration in the high Cr
A medium with at% was prepared, and the resultant was designated as Example 2-2. Example 2-1
Compared with the medium of Example 2-2, the medium of Example 2-2 has slightly higher noise, but the output attenuation rate is extremely low. In contrast, the medium of Example 2-1 has low noise, but has a high attenuation rate. This is presumably because the medium of Example 2-2 had some magnetic interaction between the magnetic layers, whereas the medium of Example 2-1 was completely broken. Therefore, it was found that by adjusting the Cr concentration in the high Cr concentration region, the interaction between the magnetic layers can be controlled appropriately, and both noise reduction and suppression of thermal demagnetization can be achieved.

<Example 3> A chemically strengthened glass substrate was heated to 200 ° C.
After heating to a thickness of 30 nm, a 30 nm thick Ti
A CoCrPtTa magnetic layer and a 10 nm carbon protective film were formed continuously. The CoCrPtTa magnetic layer was formed by simultaneous sputtering of a Co-17at% Cr-3at% Ta alloy target and a Pt target. By changing the input power, the Pt concentration was changed to 5 nm near the underlayer interface and the magnetic layer surface as schematically shown in FIG.
Only in a region of about 12 at%, and in the center of the magnetic layer, 8 at%. Further, as a comparative example, a medium was manufactured in which the Pt concentration in the magnetic layer was constant at 8 at% from the interface of the underlayer to the surface of the magnetic layer. As a result of X-ray diffraction measurement, a strong CoCrPt (00.2) peak was exhibited in both the example medium and the comparative example medium, and it was found that both mediums were vertical alignment films. Table 3 shows coercive force, squareness ratio Mr / Ms, and normalized medium noise in a DC demagnetized state obtained from a magnetization curve measured by applying a magnetic field in a direction perpendicular to the film surface.

[0024]

[Table 3]

It can be seen that by increasing the Pt concentration in the initial growth layer of the magnetic layer and in the vicinity of the surface, the coercive force and the squareness ratio are improved, and the medium noise is reduced. This is presumably because the generation of reverse magnetic domains near the initial growth layer and the surface of the magnetic layer was suppressed.

After the lubricant was applied to the medium of the present embodiment, the medium was incorporated into the magnetic storage device described in the first embodiment, and the recording / reproducing characteristics were evaluated under the condition of 8 gigabits per square inch. N was obtained. Furthermore, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference of the medium was less than 10 bits / surface, and the average failure interval was more than 300,000 hours. <Example 4> A Cr seed layer was formed on a crystallized glass substrate at room temperature.
After the formation of 50 nm, the substrate was heated to 250 ° C. by a lamp heater to form a CrTi underlayer of 50 nm and a Co-18at% Cr-12at% Pt magnetic layer in this order. Here, the CrTi underlayer was formed by simultaneous sputtering of a Cr target and a Ti target, and a concentration gradient was provided in the film thickness direction by continuously changing the input power. Further, a medium in which the underlayer was formed only of the Cr-20at% Ti alloy target was produced as a comparative example.

As a result of measuring the Auger profiles of the medium of the present embodiment and the comparative example, in the medium of the example, the Ti concentration increased almost linearly from the interface of the seed layer to the interface of the magnetic layer. 0 at%, and 20 at% near the magnetic layer interface. On the other hand, in the underlayer of the comparative medium, the Ti concentration was 20% from the interface of the seed layer to the interface of the magnetic layer.
at% was constant. When X-ray diffraction measurement was performed, as shown in Table 4, the example medium had a CoCrPt (11.0)
The intensity of the diffraction peak from the surface was strong, and the half width of the rocking curve of the diffraction peak was low.

[0028]

[Table 4]

This indicates that the magnetic layer of the example medium has better crystallinity and stronger c-axis in-plane orientation. Further, as shown in the table, it was found that providing a concentration gradient in Ti in the underlayer improved coercive force and reduced noise.

After the lubricant was applied to the medium of the present embodiment, the medium was incorporated into the magnetic storage device described in the first embodiment, and the recording / reproducing characteristics were evaluated under the condition of 8 gigabits per square inch. N was obtained. In addition, when the CSS test was performed, the coefficient of friction was not affected even after 30,000 times of CSS.
It was 0.2 or less.

[0031]

The magnetic recording medium of the present invention has a high coercive force,
It has the effect of suppressing the reproduction output attenuation due to high S * and thermal magnetic relaxation. By using the magnetic recording medium and the magnetoresistive head of the present invention, it is possible to realize a magnetic storage device having a recording density of 8 gigabits per square inch or more and an average number of failures of 300,000 hours or more. .

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a magnetic storage device according to an embodiment of the present invention, and a cross-sectional view taken along the line AA ′.

FIG. 2 is a perspective view showing a sectional structure of a magnetic head used in the magnetic storage device of the present invention.

FIG. 3 is a schematic diagram illustrating a cross-sectional structure of a magnetoresistive sensor unit of the magnetic head of FIG. 2;

FIG. 4 is a schematic diagram showing a cross-sectional structure of a magnetic recording medium according to one embodiment of the present invention.

FIG. 5 is a schematic plan view and a schematic sectional view of a film forming apparatus used in the present invention.

FIG. 6 is a diagram showing a concentration profile of each element in a magnetic layer of a magnetic recording medium according to an embodiment of the present invention in a film thickness direction.

FIG. 7 is a diagram showing a concentration profile of each element in a magnetic layer of a magnetic recording medium according to an embodiment of the present invention in a film thickness direction.

FIG. 8 is a diagram showing a concentration profile of each element in a magnetic layer of a magnetic recording medium according to an embodiment of the present invention in a film thickness direction.

[Explanation of symbols]

11 ... magnetic head, 12 ... magnetic head drive, 13 ... recording / reproduction signal processing system, 14 ... air recording medium, 15 ... magnetic recording medium drive, 21 ... substrate, 22 ... coil, 23 ... upper recording pole, 24 ... lower recording pole and upper shield layer, 25 ... magnetoresistive sensor, 26 ... conductor layer, 27 ... lower shield layer, 31 ...
Signal detection area, 32 ... Gap layer between shield layer and magnetoresistive sensor, 33 ... Buffer layer, 34 ... First magnetic layer,
35 ... intermediate layer, 36 ... second magnetic layer, 37 ... antiferromagnetic layer, 3
8 ... tapered section, 39 ... permanent magnet layer, 41 ... substrate, 42 ... underlayer, 43 ... magnetic layer, 44 ... protective film, 45 ... lubricant, 51. ..
Cathode, 52 ... target, 53 ... substrate, 54 ... substrate rotation drive.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) H01F 10/16 H01F 10/16 (72) Inventor Inoue Isao 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. In-house (72) Inventor Satoru Matsunuma 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd.Central Research Laboratories (72) Inventor Fumino Kirino 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in the Central Research Laboratory, Hitachi, Ltd. Reference) 5D006 BB02 BB07 CA01 CA05 CA06 DA03 EA03 FA09 5D034 AA02 BA02 BA30 5D091 AA10 CC05 DD03 5D112 AA03 AA05 BB05 BD04 FA04 5E049 AA04 AA09 AA10 AC05 BA06 BA12 BA16 CB02

Claims (8)

[Claims] A magnetic layer is formed on a substrate, and the magnetic layer is made of Co.
Is a hexagonal dense structure alloy film containing Cr as the main component,
A magnetic recording medium, wherein the concentration of at least one metal element of Co or Cr forming the magnetic layer changes in the film thickness direction. 2. The magnetic layer has a thickness of 5 nm or more and 20 nm or less on the substrate surface side of the magnetic layer, and an average Cr concentration of 26 at% or more and 45 at% or more.
2. The magnetic recording medium according to claim 1, wherein the following areas exist. 3. The magnetic recording medium according to claim 1, wherein the magnetic layer contains Pt, and the concentration of Pt increases continuously from the substrate side in the film thickness direction. 4. The magnetic recording medium according to claim 1, wherein the concentration of Cr contained in the magnetic layer changes so as to have one or more peaks in the thickness direction from the substrate side. 5. The magnetic layer contains oxygen, and the maximum value of the oxygen concentration in a region where the concentration of Co or Cr constituting the magnetic layer changes is 1.5 times or less the average oxygen concentration of the magnetic layer. 5. The magnetic recording medium according to claim 1, wherein: 6. A single-layer or multiple-layer underlayer is formed between the substrate and the magnetic layer, and the underlayer is made of Ti, Mo, V,
C containing at least one additional element selected from W
A magnetic recording medium comprising an alloy having a body-centered cubic structure containing r as a main component, wherein the concentration of the added element or Cr changes from the substrate side in the film thickness direction. 7. A magnetic recording medium according to claim 1, further comprising a drive unit for driving the magnetic recording medium in a recording direction, a recording unit and a reproducing unit, wherein the reproducing unit comprises a spin-valve magnetoresistive sensor. A head, means for moving the magnetic head relative to the magnetic recording medium, and recording / reproducing signal processing means for performing signal input to the magnetic head and reproduction of an output signal from the magnetic head. Magnetic storage device. 8. The spin-valve magnetoresistive sensor is formed between two shield layers made of a soft magnetic material which are separated from each other by a distance of 0.25 μm or less, and a thickness of the magnetic film. t, the product Br × t of the residual magnetic flux density Br measured by applying a magnetic field in the relative running direction of the magnetic head with respect to the magnetic recording medium during recording is 40 Gauss microns or more, and 100 Gauss microns or less. 9. The magnetic storage device according to claim 8, wherein the coercive force of the magnetic recording medium is 2600 Oe or more.