JP2000067423A - Intra-surface magnetic recording medium and magnetic storage using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic storage having high reliability at a recording density of >=4 giga-bit per square inch. SOLUTION: This intra-surface magnetic recording medium has a structure obtd. by forming a first magnetic layer 13 via a ground surface layer 12 on a substrate 11, forming an intermediate layer 14 on this first magnetic layer 13 and forming a second magnetic layer 15 on this intermediate layer 14. The coercive force of the first magnetic layer 13 is 100 to 2,000 Oe. The intermediate layer 14 is nonmagnetic or has the saturation magnetization smaller than that of the first magnetic layer 13 and the second magnetic layer 15. All of the first magnetic layer 13, the intermediate layer 14 and the second magnetic layer 15 are composed of crystal grains having substantially a hexagonal close- packed structure. The preferential growth bearings of the crystal grains of the first magnetic layer 13, the crystal grains of the intermediate layer 14 and the crystal grains of the second magnetic layer 15 are equal. The intra-surface magnetic recording medium described above is used. As a result, the high device S/N and low bit error rate are obtd. at the recording density of >=4 giga-bit per square inch and the average fault intervals may be made to >=300,000 hours.

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 and a longitudinal magnetic recording medium, and more particularly to a magnetic storage device having a recording density of 4 gigabits per square inch or more, and a longitudinal magnetic recording for realizing the same. Regarding the medium.

[0002]

2. Description of the Related Art The amount of information handled by computers is steadily increasing, and magnetic disk drives as external storage devices are required to have ever larger capacities. At present, magnetic disk drives having a recording density of a maximum of 2 gigabits per square inch have been commercialized. For the magnetic head of such a high-density magnetic disk device, a recording section and a reproducing section are separated, and a composite type head using an electromagnetic induction type magnetic head for the recording section and a magnetoresistive head for the reproducing section is adopted. ing. Since the magnetoresistive head has higher reproduction sensitivity than the conventional electromagnetic induction type head, a sufficient reproduction output can be obtained even when the recording bits are miniaturized and the leakage magnetic flux is reduced. Further, the development of a giant magnetoresistive head of the spin valve type with further improved reproduction sensitivity is also underway.

When a magnetoresistive head is used as a reproducing head, not only signals from the medium but also noise are reproduced with high sensitivity. Therefore, the medium is required to have lower noise than before. Medium noise is mainly caused by disturbance of magnetization in a magnetization transition region between recording bits, and narrowing this region leads to reduction of medium noise. For this purpose, it is effective to make the magnetic particles finer, weaken the interaction between the particles, and reduce the size of the magnetization reversal.

Although reducing the magnetization reversal size is indispensable for reducing noise, on the other hand, it has begun to be concerned that the magnetization fluctuates thermally and the recorded magnetization attenuates with time. As a method of suppressing the influence of such thermal fluctuation, there is a method of reducing the particle size dispersion of magnetic particles, suppressing the generation of excessively fine particles, and using a material having a large magnetic anisotropy constant. When a CoCrPt alloy is used for the magnetic layer, a large crystal magnetic anisotropy can be obtained by increasing the Pt concentration.

[0005]

SUMMARY OF THE INVENTION However, CoCrPt
When the Pt concentration of the alloy is increased, the coercive force also increases at the same time, so it is necessary to increase the Pt concentration within the range of the writing capability of the recording head. That is, it is considered that there is a limit to achieving both the reduction of the medium noise and the thermal stability of the recording magnetization by such a method. The present invention has been made to solve the above problems. More specifically, a highly reliable magnetic storage device with a recording density of 4 gigabits per square inch or more, and an in-plane magnetic recording medium with low medium noise and less susceptible to thermal fluctuations. It is an object to provide a magnetic recording medium.

[0006]

According to the present invention, there is provided a first magnetic layer formed on a substrate via an underlayer, an intermediate layer formed on the first magnetic layer, and a first magnetic layer formed on the first magnetic layer. An in-plane magnetic recording medium having a second magnetic layer formed on a magnetic recording medium, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, and the magnetic head being attached to the in-plane magnetic recording medium. A read / write signal processing unit for performing a signal input to the magnetic head and a read / write signal processing unit for reproducing an output signal from the magnetic head; And a coercive force of the first magnetic layer of the longitudinal magnetic recording medium of 10 Oe.
More than 200 Oe or less, the intermediate layer is non-magnetic, or smaller than the saturation magnetization of the first magnetic layer and the second magnetic layer, all the first magnetic layer and the intermediate layer and the second magnetic layer Consisting of crystal grains having a substantially hexagonal close-packed (hcp) structure, and the preferred growth orientation of the crystal grains of the first magnetic layer, the crystal grains of the intermediate layer, and the crystal grains of the second magnetic layer is equal. By doing so, the above object is achieved.

The present inventors have proposed a CrTi having a body-centered cubic (bcc) structure.
When the stability of the recording magnetization was examined using an in-plane magnetic recording medium having a general layer configuration of an alloy underlayer and a CoCrPt magnetic layer having an hcp structure, as shown in FIG. It became clear that it decayed with time. This is because in the initial growth area of the hcp-structured magnetic layer epitaxially grown on the bcc-structured underlayer, there are excessively fine particles or particles with disordered crystallinity, which fluctuate thermally. it is conceivable that. In particular, in the magnetization transition region where the recorded magnetizations face each other, a demagnetizing field having a magnitude close to the coercive force is locally applied, so that it is considered that the probability of occurrence of magnetization reversal due to thermal fluctuation is high. The present inventors have studied various methods for suppressing the effect of thermal fluctuation by a method other than increasing the Pt concentration of the magnetic layer. As shown in FIG. 1, the first magnetic layer having the hcp structure and the intermediate layer were formed on the underlayer as shown in FIG. The layer and the second magnetic layer are sequentially grown epitaxially, and the saturation magnetization and the coercive force of the first magnetic layer are sufficiently lower than those of the second magnetic layer. Further, the intermediate layer has a non-magnetic or sufficiently low saturation magnetization. As a result, it was found that by cutting the exchange coupling between the first magnetic layer and the second magnetic layer, the attenuation of the recorded signal can be suppressed. This can be for the following reasons. One is that the second magnetic layer serving as the recording layer is epitaxially grown on the intermediate layer having the same crystal structure as the hcp structure, so that the crystallinity in the initial growth portion of the second magnetic layer is small, and In addition, generation of excessively fine particles can be suppressed. Furthermore, since the magnetization of the first magnetic layer having low saturation magnetization and coercive force is in the opposite direction to the magnetization of the second magnetic layer, a strong demagnetizing field in the magnetization transition region can be reduced. It is thought that the global stability is improved. It is desirable that the coercive force of the first magnetic layer be in the range of 10 Oe to 200 Oe. If the coercive force of the first magnetic layer is lower than 10 Oe, the magnetization of the first magnetic layer may become unstable due to disturbance such as a stray magnetic field, which is not preferable. Also,
If the coercive force of the first magnetic layer is larger than 200 Oe, the ratio of being unable to be reversed by the leakage magnetic field from the magnetization transition region of the second magnetic layer increases, and as a result, the effect of reducing the demagnetizing field is weakened, which is not preferable. The material of the first magnetic layer and the intermediate layer has a lattice matching property between the first magnetic layer and the intermediate layer and a lattice matching property between the intermediate layer and the second magnetic layer, and has a function of reducing the demagnetizing field in the magnetization transition region. For this reason, it is desirable that Co and Cr be the main components, and the concentration of Cr be 26 at% or more and 40 at% or less. CoCr alloys become non-magnetic when the Cr concentration is about 25 at% in the bulk state, but in a thin film formed when heated to several hundred degrees, Cr segregates at the grain boundaries and the like, resulting in modulation of the composition. As a result, a region in which the Cr concentration is lower than 25 at% is generated, and magnetism is exhibited. If the Cr concentration is lower than 26 at%, the saturation magnetization increases, and the medium noise increases, which is not preferable. Also,
If the Cr concentration is higher than 40 at%, it is difficult to obtain good crystallinity in the hcp structure, and furthermore, the magnetization becomes extremely small, and the effect of reducing the demagnetizing field is lost, which is not preferable. The material of the first magnetic layer and the intermediate layer does not necessarily have to be a CoCr binary alloy, and Ta, Ti,
Mo, W, etc. may be added. Ge or Si may be added to optimize the coercive force. However, if the added amount of these elements is too large, the element may become amorphous, so that it is necessary to use the element within a range where the crystallinity is not deteriorated. The sum of the thicknesses of the first magnetic layer and the intermediate layer is desirably 5 nm or more and 20 nm or less from the viewpoint of maintaining good crystallinity and suppressing an increase in particle size. If the thickness is more than 20 nm, the particle size increases, and the magnetizations of the first magnetic layer and the intermediate layer become too large, and the medium noise increases, which is not preferable. If the thickness is less than 5 nm, both the effect of improving the crystallinity of the initial growth portion of the second magnetic layer and the effect of reducing the demagnetizing field are undesirably reduced. Also, by increasing the Cr concentration of the intermediate layer compared to the Cr concentration of the first magnetic layer, and cutting the exchange coupling between the first magnetic layer and the second magnetic layer in the intermediate layer, the first magnetic layer has The demagnetizing field reduction effect can be effectively used.

In order to obtain a higher output resolution in the longitudinal magnetic recording medium of the present invention, it is desirable that the c-axis of the recording layer be oriented in the film plane. The crystal orientation of such a recording layer is bcc
It has a structure, and is obtained by using a base layer whose (001) plane is parallel to the substrate and epitaxially growing the (11.0) plane of the first magnetic layer thereon. In addition, an underlayer whose (211) plane is parallel to the substrate may be used, and the (10.0) plane of the first magnetic layer may be epitaxially grown thereon. In either case, the c-axis of the second magnetic layer can be directed in the film plane.

It is necessary to use a substrate having excellent surface smoothness. Specifically, A substrate having NiP formed on the surface is required.
An l-Mg substrate, a glass substrate, a SiO2 substrate, a SiC substrate, a carbon substrate, or the like can be used. If the substrate material has poor adhesion to the underlayer or the desired crystal orientation of the underlayer cannot be obtained, a substantially amorphous precoat layer is provided between the substrate and the underlayer. Forming solves these problems.

As a protective layer of the magnetic layer, carbon having a thickness of 5 to 20 nm is formed, and a lubricating layer of perfluoroalkyl polyether or the like is formed with a thickness of 2 to 20 nm, so that a highly reliable layer is formed. An in-plane magnetic recording medium is obtained. In addition, by using hydrogenated carbon, nitrogen-added carbon, or the like as a material for the protective layer, sliding resistance and corrosion resistance can be improved.

The magnetoresistive sensor portions of the reproducing magnetoresistive magnetic head used in the magnetic storage device of the present invention have a mutual resistance of 0.25 μm.
It is formed between two soft magnetic shield layers separated by a distance of not more than m. 0.25μm spacing between the shield layers
A larger value is not preferable because the resolution is reduced.

Further, the magneto-resistance effect type magnetic head is provided between a plurality of conductive magnetic layers which generate a large resistance change when their magnetization directions are relatively changed by an external magnetic field, and between the conductive magnetic layers. Since the reproduction signal can be increased by configuring with a magnetoresistive sensor including a conductive nonmagnetic layer arranged, the
A highly reliable magnetic storage device with a recording density of gigabit or more can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIGS. 3 (a) and 3 (b) are a schematic plan view and a schematic longitudinal sectional view of a magnetic storage device according to this embodiment. This device includes an in-plane magnetic recording medium 31 and
This is a magnetic storage device having a well-known configuration including a driving unit 32 that rotationally drives the magnetic head 33, a magnetic head 33 and its driving unit 34, and a recording / reproducing signal processing unit 35 for the magnetic head. FIG. 4 shows a schematic diagram of the structure of the magnetic head used in the magnetic storage device. This magnetic head is a recording / reproducing separation head in which an electromagnetic induction type magnetic head for recording and a magnetoresistive head for reproduction formed on a magnetic head slider base 47 are combined. The recording magnetic head is an inductive type thin film magnetic head including a pair of recording magnetic poles 41 and 42 and a coil 43 interlinked with the recording magnetic poles, and the thickness of the gap layer between the recording magnetic poles is 0.3 μm. The magnetic poles 42 are both thick.
A pair with the magnetic shield layer 46 of 1 μm also serves as a magnetic shield for a magnetic head for reproduction.
0.2 μm. The reproducing magnetic head is a magnetoresistive head including a magnetoresistive sensor 44 and a conductor layer 45 serving as an electrode. In FIG. 4, the gap layer and the shield layer between the recording magnetic poles are omitted.

FIG. 5 shows a longitudinal sectional structure of the magnetoresistive sensor. The signal detection region 51 of the magnetoresistive sensor is composed of a portion in which a lateral bias layer 53, a separation layer 54, and a magnetoresistive ferromagnetic layer 55 are sequentially formed on a gap layer 52 of Al oxide. For the magnetoresistive ferromagnetic layer 55, a 20 nm NiFe alloy was used. For the lateral bias layer 53, 25 nm of NiFeNb was used.
Any ferromagnetic alloy such as FeRh having relatively high electric resistance and good soft magnetic properties may be used. The lateral bias layer 53 is magnetized in an in-plane direction (lateral direction) perpendicular to the current by a magnetic field induced by a sense current flowing through the magnetoresistive ferromagnetic layer 55, and a lateral bias is applied to the magnetoresistive ferromagnetic layer 55. Apply a magnetic field. Thus, the magnetic sensor can obtain a linear reproduction output with respect to the leakage magnetic field from the medium. For the separation layer 54 for preventing the shunt of the sense current from the magnetoresistive ferromagnetic layer 55, Ta having relatively high electric resistance was used, and the film thickness was 5 nm. At both ends of the signal detection region 51, there are tapered portions 56 which are processed into a tapered shape. The tapered portion 56 includes a permanent magnet layer 57 for turning the magnetoresistive magnetic layer 55 into a single magnetic domain,
A pair of electrodes 5 for taking out signals formed thereon
8. It is important that the permanent magnet 57 has a high coercive force and the magnetization direction does not change easily.
Pt alloy or the like is used.

FIG. 1 shows the layer structure of the magnetic recording medium used in this embodiment. As the substrate 11, an Al-Mg alloy substrate having an outer diameter of 95 mmφ and NiP plating on the surface was used. A 10 nm Cr-15at% Ti alloy layer as the underlayer 12 and a 10 nm
Co-30at% Cr alloy layer of 5 nm, Co-40 of 5 nm as the intermediate layer 14
The at% Cr alloy layer was used as the second magnetic layer 15 with 14 nm of Co-22 at% C.
An r-10at% Pt alloy layer was continuously formed by a DC magnetron sputtering method using a carbon layer of 6 nm as the protective layer 16. The film formation conditions were as follows: partial pressure of argon gas was 5 mTor
r, the input power was 1 kW, and the substrate temperature was 300 ° C. Lubrication layer 1
In No. 7, a perfluoroalkyl polyether-based material was diluted with a fluorocarbon material and applied. As a comparative example, as shown in FIG. 6, a medium was prepared in which the magnetic layer 61 was directly formed on the underlayer 12 without using the first magnetic layer and the intermediate layer. Here, the film thickness of the magnetic layer 61 is 14 nm, and Co-2
A 2 at% Cr-10 at% Pt alloy layer (Comparative Example 1) was used.

Signals were written at a linear recording density of 225 kFCI on the media of this embodiment and the comparative example, and the stability of the recorded signals was examined by measuring the change over time of the reproduced signals. FIG.
As shown in the figure, in the medium of Comparative Example 1, the reproduction output decreased with time, and a decrease of about 4% was observed after 4 days. On the other hand, in the medium of the present example, it hardly decreased after 4 days. However, the decrease after 18 days could be reduced to about 2%. The large decrease in the reproduction output of the medium of Comparative Example 1
It is considered that excessively fine particles or particles having poor crystallinity exist in the initial growth portion of the magnetic layer, and these magnetizations fluctuate thermally. In particular, since a demagnetizing field acts in a magnetization transition region where recording magnetizations face each other, there is a possibility that the probability of occurrence of magnetization reversal due to thermal fluctuations is increased. In the medium of the present embodiment, since the second magnetic layer and the intermediate layer have the same crystal structure and a close lattice spacing, the disorder of the crystallinity of the initial growth portion of the second magnetic layer is small, and excessively fine particles are formed. Generation can be suppressed. Further, the first magnetic layer having a weak magnetization and coercive force forms a magnetization opposite to that of the second magnetic layer,
It is considered that the reduction of the demagnetizing field in the magnetization transition region contributes to the stability of the recording magnetization of the second magnetic layer.

The recording / reproducing characteristics of the medium of this embodiment were evaluated under the conditions of a head flying height of 30 nm, a linear recording density of 240 kFCI, and a track density of 13 kTPI by incorporating the medium of the present invention into the magnetic storage device.
An apparatus S / N of 1.9 was obtained. Also, the input signal to the magnetic head is subjected to 16-17 code modulation processing, so that
Recording and reproduction could be performed at a recording density of 3 gigabits per square inch in a temperature range of ° C. In addition, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference was 10 bits / plane or less, and 300,000 hours were averaged between failures.

Embodiment 2 FIG. 8 shows the layer structure of the magnetic recording medium used in this embodiment. The substrate 11 has an outer diameter of 95 mmφ NiP
An Al-Mg alloy substrate having a plated surface was used. A 10 nm Cr layer as the first underlayer 81 and a second underlayer 82
A 10 nm Cr-15at% Ti layer is used as the first magnetic layer 13 with a 10 nm Co
-30at% Cr alloy layer, 5nm Co-40at% Cr as the intermediate layer 14
14 nm of Co-22at% Cr-10a alloy layer as the second magnetic layer 15
A t% Pt alloy layer was continuously formed by a DC magnetron sputtering method using a 6 nm carbon layer as the protective layer 16. The film forming conditions and the lubrication layer 17 are the same as in the medium of the first embodiment.

The medium of the present embodiment and the medium of the first embodiment
A signal was written at a linear recording density of I, and medium noise and output resolution were measured. Table 1 shows the results. Here, as the medium noise, a value normalized by multiplying the measured medium noise by the square root of the reproduction track width and dividing by the reproduction output of 5 kFCI was used. The output resolution was expressed as a percentage obtained by dividing the reproduction output of 225 kFCI by the reproduction output of 5 kFCI. The medium of the present embodiment showed the same value of the medium noise as the medium of the first embodiment, and the output resolution was increased by 3%. Examination of the crystal orientation of both media by X-ray diffraction revealed that the media of this example had a stronger (001) orientation of the underlayer, and as a result, the (1)
1.0) The orientation was strong. From this result, it can be seen that it is effective to orient the c-axis of the magnetic layer in the film plane to improve the output resolution.

The medium of this embodiment is incorporated in the magnetic storage device of the first embodiment, and the head flying height is 30 nm and the linear recording density is 240 kFC.
When the recording and reproducing characteristics were evaluated under the conditions of I and a track density of 13 kTPI, an apparatus S / N of 2.0 was obtained. In addition, by subjecting the input signal to the magnetic head to 16-17 code modulation processing, 10
3 ° C per square inch in the temperature range of 50 ° C to 50 ° C
Recording and reproduction were possible at a gigabit recording density. In addition, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference was 10 bits / plane or less, and 300,000 hours were averaged between failures.

Embodiment 3 FIG. 9 shows the layer configuration of the magnetic recording medium used in this embodiment. A chemically strengthened glass having an outer diameter of 65 mmφ was used for the substrate 91. 50 nm of Co as the precoat layer 92
-30at% Cr-10at% Zr alloy, 10nm Cr-1
5at% Ti alloy layer, 10nm Co-30at% as the first magnetic layer 13
A Cr alloy layer, a 5 nm Co-40at% Cr alloy layer as the intermediate layer 14, a 14nm Co-22at% Cr-10at% Pt alloy layer as the second magnetic layer 15, and a 6nm carbon layer as the protective layer 16. Used, DC
It was formed continuously by magnetron sputtering. The film forming conditions and the lubrication layer 17 are the same as in the medium of the first embodiment. As a comparative example, a medium in which the underlayer 12 was formed directly on the substrate 91 without using the precoat layer 92 (Comparative Example 2)
Was prepared.

Signals were written at a recording density of 225 kFCI on the media of this embodiment and Comparative Example 2, and the media noise and output resolution were measured. Table 1 also shows the results.

[0023]

[Table 1]

In the medium of this embodiment, both the medium noise and the output resolution were equivalent to those of the medium of the first embodiment. However, the medium of Comparative Example 2 had a large increase in the medium noise and a large output resolution. Has dropped. When the crystal orientation was examined by the X-ray diffraction method, the underlayer 12 was (001) oriented in the medium of the present example, whereas the underlayer 12 was
Was (110) oriented. In the case of the crystal orientation as in Comparative Example 2, the c-axis of the second magnetic layer rises about 28 degrees from the film surface.
Thus, it is considered that the medium noise increased and the output resolution decreased. It should be noted that the precoat layer of the medium of this embodiment is considered to be amorphous because the halo peaks. As described above, when a substrate made of glass or the like in which the (001) orientation of the underlayer is difficult to obtain is used, it can be seen that it is effective to insert an amorphous precoat layer between the substrate and the underlayer. .

The medium of this embodiment is incorporated in the magnetic storage device of the first embodiment, and the head flying height is 30 nm and the linear recording density is 240 kFC.
When the recording and reproduction characteristics were evaluated under the conditions of I and a track density of 13 kTPI, an apparatus S / N of 1.9 was obtained. In addition, by subjecting the input signal to the magnetic head to 16-17 code modulation processing, 10
3 ° C per square inch in the temperature range of 50 ° C to 50 ° C
Recording and reproduction were possible at a gigabit recording density. In addition, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference was 10 bits / plane or less, and 300,000 hours were averaged between failures.

Embodiment 4 In a magnetic storage device having a configuration similar to that of Embodiment 1, it is preferable to use a spin valve type as shown in FIG. 10 for the magnetoresistive sensor 24 because a larger output can be obtained. Signal detection area 1 of magnetic sensor
01, a 5 nm Ta buffer layer 103, a 7 nm first magnetic layer 104, a 1.5 nm Cu intermediate layer 105, a 3 nm second magnetic layer 106, and a 10 nm Fe-20at% on the Al oxide gap layer 102. M
This is a structure in which n antiferromagnetic alloy layers 107 are sequentially formed.
For the first magnetic layer 104, a Ni-20at% Fe alloy was used, and for the second magnetic layer 106, Co was used. The magnetization of the second magnetic layer 106 is fixed in one direction by the exchange magnetic field from the antiferromagnetic alloy 107. On the other hand, the first magnetic layer 10 in contact with the second magnetic layer 106 via the non-magnetic intermediate layer 105
The direction of magnetization 4 changes due to the leakage magnetic field from the longitudinal magnetic recording medium. With the change in the relative directions of the magnetizations of the two magnetic layers, the resistance of the entire three layers changes. This phenomenon is called a spin valve effect. In this embodiment, a spin-valve magnetic head utilizing this effect is used for a magnetoresistive sensor. In addition, the permanent magnet layer 1
The tapered portion 108 composed of 09 and the electrode 110 is the same as that of the magnetoresistive sensor shown in FIG.

The medium of Example 1 was incorporated into the above magnetic storage device, and the recording and reproduction characteristics were evaluated under the conditions of a head flying height of 30 nm, a linear recording density of 274 kFCI, and a track density of 15.6 kTPI. As a result, an apparatus S / N of 2.0 was obtained. Was. Also, the input signal to the magnetic head is subjected to 16-17 code modulation processing, so that
Recording and reproduction could be performed at a recording density of 4 gigabits per square inch in a temperature range of 0 ° C. In addition, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference was 10 bits / plane or less, and 300,000 hours were averaged between failures.

[0028]

According to the longitudinal magnetic recording medium of the present invention, the disorder of the crystallinity in the initial growth portion of the recording layer is small, and the generation of excessively fine particles can be suppressed. Further, the first magnetic layer forms a magnetization opposite to that of the second magnetic layer,
The demagnetizing field in the magnetization transition region is reduced, and the stability of the recorded magnetization is obtained. By combining the in-plane magnetic recording medium of the present invention with a magnetoresistive head,
A highly reliable magnetic storage device with a recording density of gigabit or more can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a layer structure of a longitudinal magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing a temporal change of a standardized reproduction signal.

FIGS. 3A and 3B are a schematic plan view and a vertical sectional view taken along the line AA ′ of a magnetic storage device according to an embodiment of the present invention, respectively.

FIG. 4 is a schematic three-dimensional view showing a sectional structure of a magnetic head in the magnetic storage device of the present invention.

FIG. 5 is a schematic view of a longitudinal sectional structure of a magnetoresistive sensor section of a magnetic head in the magnetic storage device of the present invention.

FIG. 6 is a diagram showing a layer configuration of a longitudinal magnetic recording medium according to a comparative example of the present invention.

FIG. 7 is a diagram showing a temporal change of a standardized reproduction signal.

FIG. 8 is a diagram showing a layer configuration of a longitudinal magnetic recording medium according to one embodiment of the present invention.

FIG. 9 is a diagram showing a layer configuration of a longitudinal magnetic recording medium according to one embodiment of the present invention.

FIG. 10 is a schematic diagram of a longitudinal sectional structure of a spin valve type magnetoresistive sensor section of a magnetic head in the magnetic storage device of the present invention.

[Explanation of symbols]

11 ... substrate, 12 ... underlayer, 13 ... keeper layer, 14 ... recording layer, 15 ... protective layer, 16 ...
・ Lubricating layer, 31 ・ ・ ・ In-plane magnetic recording medium, 32 ・ ・ ・ In-plane magnetic recording medium drive, 33 ・ ・ ・ Magnetic head, 34 ・
..Magnetic head drive unit, 35 ... recording / reproducing signal processing system, 41 ... recording magnetic pole, 42 ... magnetic pole / magnetic shield layer, 43 ... coil, 44 ... magnetoresistive element, 45 ... conductor layer, 46 ... magnetic shield layer, 4
7 ... slider base, 51 ... signal detection area of magnetic sensor, 52 ... gap layer, 53 ... lateral bias layer, 54 ... separation layer, 55 ... magnetoresistive ferromagnetic layer,
56: tapered portion; 57: permanent magnet layer;
..Electrode, 81 ... first underlayer, 82 ... second underlayer, 91 ... substrate, 92 ... precoat layer, 101
... Signal detection area of magnetic sensor, 102 ... Gap layer, 103 ... Buffer layer, 104 ... First magnetic layer, 105 ... Intermediate layer, 106 ... Second magnetic layer Reference numeral 107 denotes an antiferromagnetic alloy layer, 108 denotes a tapered portion, 109 denotes a permanent magnet layer, 110 denotes an electrode.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Ichiro Tamai 1-280 Higashi Koigakubo, Kokubunji, Tokyo, Japan Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Satoru Matsunuma 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 5D006 BB02 BB07 BB08 CA05 DA03 FA09 5D034 AA02 BA02 BB20

Claims (9)

[Claims] A first magnetic layer formed on a substrate via an underlayer, an intermediate layer formed on the first magnetic layer, and a second magnetic layer formed on the intermediate layer. In the in-plane magnetic recording medium having the structure described above, the coercive force of the first magnetic layer is 10 Oe or more and 200 Oe or less, and the intermediate layer is non-magnetic, or more than the first magnetic layer and the second magnetic layer. Also has a small saturation magnetization, and the first magnetic layer, the intermediate layer and the second magnetic layer are all made of crystal grains having a hexagonal close-packed structure, and the crystal of the first magnetic layer 2. The longitudinal magnetic recording medium according to claim 1, wherein the crystal grains of the intermediate layer and the crystal grains of the second magnetic layer have the same preferential growth orientation. 2. A c-axis of substantially hexagonal close-packed crystal grains constituting a first magnetic layer, an intermediate layer, and a second magnetic layer of the longitudinal magnetic recording medium is substantially parallel to the substrate. 2. The longitudinal magnetic recording medium according to claim 1, wherein: 3. The longitudinal magnetic recording medium according to claim 1, wherein the first magnetic layer and the intermediate layer are mainly composed of Co and Cr, and the concentration of Cr is 26 at% or more and 40 at%.
And the Cr concentration of the first magnetic layer is
3. The in-plane magnetic recording medium according to claim 1, wherein the concentration is lower than the Cr concentration. 4. The in-plane magnetic recording medium according to claim 1, wherein the sum of the thicknesses of the first magnetic layer and the intermediate layer of the in-plane magnetic recording medium is 5 nm or more and 20 nm or less. Magnetic recording medium. 5. The underlayer of the longitudinal magnetic recording medium is substantially composed of crystal grains having a body-centered cubic structure, and (0)
The in-plane magnetic recording medium according to claim 2, wherein the (01) plane is substantially parallel to the substrate. 6. The underlayer of the longitudinal magnetic recording medium is substantially composed of crystal grains having a body-centered cubic structure, and (2)
11. The longitudinal magnetic recording medium according to claim 2, wherein the surface is substantially parallel to the substrate. 7. The in-plane magnetic recording medium according to claim 1, further comprising a substantially amorphous precoat layer between the substrate and the underlayer of the in-plane magnetic recording medium. Magnetic recording medium. 8. An in-plane magnetic recording medium having a magnetic layer formed on a substrate via an underlayer, a drive unit for driving the medium in a recording direction, a magnetic head comprising a recording unit and a reproducing unit, A magnetic storage device comprising: a means for moving a magnetic head relative to the longitudinal magnetic recording medium; and a recording / reproducing signal processing means for reproducing a signal input from the magnetic head and an output signal from the magnetic head. A longitudinal magnetic recording medium is constituted by the longitudinal magnetic recording medium according to any one of claims 1 to 7, and a reproducing section of the magnetic head is constituted by a magnetoresistive magnetic head. Magnetic storage device. 9. The magneto-resistance effect type magnetic head is disposed between a plurality of conductive magnetic layers which generate a large resistance change due to their magnetization directions relatively changing by an external magnetic field. 9. The magnetic storage device according to claim 8, comprising a magnetoresistive sensor including a conductive nonmagnetic layer formed.