JPH07225935A - Magnetic recording medium and magnetic storage - Google Patents

Abstract

PURPOSE:To make DC bias sputtering adoptable even in the case of an electric nonconductive substrate and to obtain a magnetic recording medium having high coercive force and a large capacity magnetic storage. CONSTITUTION:Electric conductive films 12, 12' are formed on an electric nonconductive substrate 11 and then underlayers 13, 13' and magnetic layers 14, 14' are successively formed while ensuring the contact of each of the films 12, 12' with a substrate electrode and applying DC bias voltage. At this time, the product of residual magnetization and film thickness is regulated to 10-150G.mum and coercive force to 1,600O-4,000Oe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic drum, a magnetic tape, a magnetic disk and a magnetic card and a magnetic storage device, and more particularly to a thin film type magnetic recording medium suitable for ultra high density. To a magnetic storage device using a different magnetic recording medium.

[0002]

2. Description of the Related Art With the remarkable development of electronic computers in recent years, an information society has developed, and the amount of information handled by individuals has been increasing. Accordingly, increasing the capacity of the external storage device and increasing the speed of access are essential issues.
In particular, the magnetic disk device is a storage device suitable for high-density storage, and the demand for high speed, small size, and large capacity is further increasing. The magnetic recording medium used in the magnetic disk device is
A coating type magnetic recording medium in which a powder of an oxide magnetic material is coated on a substrate and a thin film type magnetic recording medium in which a thin film of a metal magnetic material is deposited or sputtered on the substrate are known.
This thin film type magnetic recording medium is suitable for higher density recording because the density of the magnetic substance in the recording film is higher than that of the coating type magnetic recording medium. Therefore, the thin film magnetic recording medium has come to be used in most of the magnetic disk devices manufactured at present.

The substrate of the thin film magnetic recording medium has hitherto been Ni.
-P plated Al-Mg alloys have been mainly used. However, recently, magnetic disk devices have been installed in small portable computers, and securing reliability against impact has become an important issue. Therefore, harder tempered glass, crystallized glass, carbon substrate Etc. have come to be used.

As a general structure of a thin film magnetic recording medium, it is well known that a nonmagnetic underlayer, a magnetic layer and a protective layer are sequentially formed on a substrate. In order to increase the storage capacity of the magnetic disk device, it is necessary to increase the coercive force of the thin film magnetic recording medium. Recently, as a method of increasing the coercive force, a bias sputtering method, in which a negative bias voltage is applied to a substrate when a nonmagnetic underlayer and a magnetic layer are formed, has been attracting attention. N
For a substrate having conductivity such as an iP plated Al-Mg alloy, for example, IEE Transactions on Magnetics, 26, 1282
DC bias has been used as described in P., 1990. On the other hand, a non-conductive substrate such as tempered glass is disclosed in, for example, Digest of Intermag Conference, EB-04, April 13, 1993.
RF bias is used as described in ~ 16 days.

[0005]

It is expected that the remanent magnetization film thickness product of the medium for high density in the future will be 150 G · μm or less in order to reduce the demagnetizing field. At this time, the coercive force should be at least 1600 Oe. However, it is difficult to satisfy this specification with a normal sputtering method. Therefore, it is desirable to use a bias sputtering method in which a negative bias voltage is applied to the substrate when forming the nonmagnetic underlayer and the magnetic layer. The conventional thin film medium manufacturing method can only adopt the RF bias sputtering method when a hard non-conductive substrate compatible with future small magnetic disk devices is used. However, when the medium is produced by this method, the production facility becomes large-scale and, at the same time, the production efficiency is remarkably deteriorated. Moreover, sufficient electromagnetic conversion characteristics for high density recording cannot be obtained.

When the remanent magnetization film thickness product of the medium becomes 150 G · μm or less, in the conventional inductive magnetic head and the recording / reproducing separated type head for reproducing by using the magnetoresistive effect having low reproducing sensitivity, It is difficult to bring out the full potential of the product. Therefore, a magnetic head having high reproduction sensitivity is indispensable, and a signal processing circuit corresponding to this magnetic head must be combined. Furthermore, the circuit for modulating / demodulating the signal must be compatible with high density recording. By combining these elemental technologies,
It is possible to realize an apparatus compatible with high density recording.

A first object of the present invention is to make the DC bias sputtering method usable even when a non-conductive substrate is used.

A second object of the present invention is to provide a magnetic recording medium having good electromagnetic conversion characteristics during high density recording.

A third object of the present invention is to provide a large-capacity magnetic storage device which can fully utilize the characteristics of a magnetic recording medium having a good electromagnetic conversion characteristic during high density recording.

[0010]

To achieve the first object, the present invention directly forms a conductive film on a non-conductive substrate and directly applies a DC bias voltage to the conductive film. Alternatively, a magnetic layer is laminated with a nonmagnetic underlayer interposed. At this time, a certain amount of restriction occurs because a recording area for recording information needs to be secured in a portion where the conductive film and the substrate electrode jig are in contact with each other. In particular, since it is desired to effectively utilize the middle portion of the disk as a recording area, it is not desirable to make contact here. On the other hand, the innermost portion of the disk is chucked by the spindle, so that even if a film is formed, it is not used as a recording area. In addition, since the slider of the magnetic head is removed from the disc surface at the outer peripheral portion,
The recording area is not used in the extreme outer periphery. Therefore, the method for ensuring electrical contact between the conductive film and the substrate electrode jig is to make surface contact or point contact at the inner or outer peripheral portion of the medium, or the inner or outer peripheral portion of the medium. It is desirable to use a method of contacting the conductive film wrapping around the side surface of the above with a surface or a point. Further, since the same result can be obtained by applying the bias only when forming the magnetic layer, the bias may be applied only when forming the magnetic layer. However, it is not preferable to apply the bias only when the non-magnetic underlayer is formed, because there is almost no effect. In the film thus formed by applying the bias, the concentration of the sputter gas becomes high.
The feature is that the Co (110) plane has a large interplanar spacing.

In order to achieve the second object, the present invention sets the residual magnetization film thickness product of the magnetic recording medium to 10 G · μm or more and 15
0 G · μm or less, coercive force of 1600 Oe or more and 4000 O
e or less. At this time, it is more desirable to have a multilayer structure in which the magnetic layer is divided by a non-magnetic intermediate layer in order to reduce noise.

In order to achieve the third object, the present invention utilizes a recording-only magnetic head using a magnetic material having a saturation magnetic flux density of 1.2T or more in at least a part of a magnetic pole, and a giant magnetoresistive effect. The read-only magnetic head is combined. At this time, a signal processing circuit by maximum likelihood decoding and a circuit that corrects the asymmetry of the reproduction signal of the magnetic head using the giant magnetoresistive effect are combined to set the flying height of the slider of the magnetic head to 0.05 μm or less. Is more desirable.

The conductive film of the magnetic recording medium of the present invention comprises C, T
i, V, Cr, Cu, Zn, Nb, Mo, Ru, Rh,
Pd, Ag, Ta, W, Pt, Au, Ni-P, Cr-
P is preferable in controlling the crystallinity, crystal orientation, and crystal grain size of the underlayer and the magnetic layer. Also, a mixture of two or more of these elements may be used.
Further, it is more preferable to form an oxide layer, a nitrogen-containing layer, or a carbon-containing layer having a thickness of 0.1 nm or more and 10 nm or less on the surface of the conductive film in order to increase the coercive force.

The nonmagnetic underlayer of the magnetic recording medium of the present invention is
Cr, Mo, W, Ta, Nb or Cr-P, Cr-Ti, Cr-V, Mo-Nb containing these as main components
Mo-Pt, Mo-Ge, W-Cr, W-Ta, WS
The alloy such as i is preferable in controlling the crystallinity, crystal orientation, and crystal grain size of the magnetic layer. The thickness of the non-magnetic underlayer is more preferably 0.1 nm or more and 500 nm or less in order to improve the S / N. Further, in order to have a multilayer magnetic recording medium structure, it is preferable to provide a non-magnetic intermediate layer between the magnetic layers in order to divide the magnetic layer,
In this case, the composition is preferably the same as that of the nonmagnetic underlayer. At this time, the thickness of the intermediate layer is 0.1 nm or more and 5 n
It is more preferable that it is m or less in order to improve the overwrite characteristic. Further, in a multilayer magnetic recording medium, even if the nonmagnetic intermediate layer is not actually formed by a physical film forming method, it is possible to simply stop the film formation of the magnetic layer and repeat the film formation. Since an oxide layer, a nitrogen-containing layer, or a carbon-containing layer having a thickness of 0.1 nm or more is formed on the surface, this method may be used.

The magnetic layer of the magnetic recording medium of the present invention is CoC.
rPt, CoCrTa, CoNiPt, CoNiTa, C
oSiPt, CoSiTa, CoCrPtB, CoCr
It is preferable to use a magnetic alloy containing Co as a main component such as TaB because high coercive force and recording density characteristics can be obtained. The thickness of the magnetic layer is more preferably 0.2 nm or more and 50 nm or less per magnetic layer in consideration of the multilayer medium in order to improve the S / N.

[0016]

The reason why the coercive force is increased by using the bias sputtering method is not clear at present, but the following effects can be considered.

(1) The concentration of the sputtering gas contained in the magnetic film is increased, and this gas is taken into the magnetic crystal grains,
Inducing magnetostriction. At the same time, the isolation of the magnetic crystal grains is promoted, and the interaction between the crystal grains is cut off. (2) Ions collide with the surface of the substrate at high speed, resulting in high surface energy (substantially increase in substrate temperature). (3) It is possible to suppress the growth of weakly bonded crystals and selectively control the crystal growth. (4) Clean the laminated surface (remove impurities).

It can be construed that the magnetic anisotropy / strain of the magnetic film increases and the coercive force increases due to the above factors. In order to use the DC bias sputtering method even when using a non-conductive substrate, a conductive film may be formed on the substrate in advance. If electrical conduction can be secured between the conductive film and the substrate electrode to ensure continuity, a DC bias can be easily applied.
Further, it is preferable to form an oxide layer, a nitrogen-containing layer, or a carbon-containing layer having a thickness of 0.1 nm or more and 10 nm or less on the surface of the conductive film, because the coercive force is further improved. If the oxide layer, nitrogen-containing layer, or carbon-containing layer is as thin as this, conduction can be secured due to scratches or tunneling when a jig for applying a bias is brought into contact with the substrate, and sufficient bias can be applied. There is no.

By using the present DC bias sputtering method and keeping the coercive force at 1600 Oe or more and setting the residual magnetization film thickness product to 150 G · μm or less, a high recording density characteristic can be obtained. However, if the remanent magnetization film thickness product is smaller than 10 G · μm, the effect of thermal fluctuation increases, and the coercive force is significantly deteriorated even when the bias sputtering method is used. Moreover, if it is 10 G · μm or less, the reproduction output becomes too small, which is not preferable. Further, when the coercive force is 1600 Oe or more, a high reproduction output can be obtained at a high recording density, but when it is higher than 4000 Oe, the writing capability of the magnetic head is far exceeded, so that the overwrite characteristic is significantly deteriorated, which is preferable. Absent.

The structure of the medium manufactured using this method is not limited to the structure in which the magnetic layer such as the underlayer, the magnetic layer and the protective layer is a single layer, but also the underlayer, the magnetic layer, the non-magnetic intermediate layer, the magnetic layer,
It may have a multilayer magnetic structure such as a non-magnetic intermediate layer, ..., Protective layer. In the multi-layer magnetic structure, by thinning each magnetic layer and interposing a non-magnetic intermediate layer having a thickness of 0.1 nm or more between the magnetic layers, the magnetic layers can be laminated while the crystal grains are miniaturized, and substantially each layer is formed. Exchange interactions can be reduced to the point where they are considered to be nearly magnetically independent. In this case, the magnetic interaction between the magnetic layers can be weakened and the noise can be reduced according to the statistical sum, so that the noise can be further reduced as compared with the single layer medium. Regarding the output, the reproduction output can be increased by stacking a large number of magnetic layers. However, here, even if the non-magnetic intermediate layer is not actually formed by a physical film-forming method, the process of temporarily stopping the film formation of the magnetic layer and then forming the film again can be repeated. Oxide layer of 0.1 nm or more,
The nitrogen-containing layer or the carbon-containing layer is formed, and substantially the same effect as providing the non-magnetic intermediate layer between the magnetic layers is obtained. For these reasons, a high S / N (signal-to-noise ratio) is obtained in a multilayer magnetic recording medium in which a non-magnetic intermediate layer is provided between magnetic layers.
Can be realized.

A magnetic recording medium of the present invention, a recording-only magnetic head using a magnetic material having a saturation magnetic flux density of 1.2T or more in at least a part of the magnetic pole, and a reproduction-only magnetic utilizing the giant magnetoresistive effect. By combining the heads, a high-quality reproduction signal can be obtained, and a large-capacity magnetic disk device that is at least twice as large as the conventional one can be realized. This is because a recording-only magnetic head using a magnetic material having a saturation magnetic flux density of 1.2T or more in at least a part of the magnetic pole has a larger recording magnetic field than a conventional magnetic head, and a medium having a high coercive force is sufficient. This is because recording becomes possible, the overwrite characteristic is remarkably improved, and the recording magnetic field becomes steep, so that the medium noise is suppressed to a low level. Further, it is one of the major factors that the read-only magnetic head utilizing the giant magnetoresistive effect can obtain a read output more than 5 times that of the conventional induction type magnetic head. In addition to the combination of this medium and the magnetic head, a signal processing circuit by maximum likelihood decoding and a circuit for correcting the asymmetry of the reproduction signal of the magnetic head utilizing the giant magnetoresistive effect are combined.
By setting the flying height of the slider of the magnetic head to be 0.05 μm or less, it is possible to realize a large-capacity magnetic storage device that is three times or more compared with the conventional one.

[0022]

【Example】

(Example 1) FIG. 1 is a sectional view of a magnetic recording medium of the present invention. Each layer was formed by a sputtering method. As the non-conductive substrate 11, a tempered glass substrate, a canasite (crystallized glass) substrate, a ceramic substrate such as SiC, a plastic substrate, a TiO substrate, a Ti alloy substrate or the like is used. The conductive films 12 and 12 'are made of C, Ti, V, Cr, Cu, Z.
n, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W,
Pt, Au, Ni-P, Cr-P, or a mixture of two or more of these is used.
13, 13 'are Cr, Mo, W, Ta, Nb or Cr-P, Cr-Ti, Cr- containing these as the main components.
V, Mo-Nb, Mo-Pt, Mo-Ge, W-Cr,
Non-magnetic underlayer made of an alloy such as W-Ta or W-Si, 1
4, 14 'are CoCrPt, CoCrTa, CoNiP
t, CoNiTa, CoSiPt, CoSiTa, Co
It is a magnetic layer containing Co such as CrPtB and CoCrTaB as a main component. Note that plasma cleaning may be performed with Ar or the like between the substrate and the conductive film in order to reduce the influence of impurities and the like on the substrate surface. Also, 15 and 15 'are C and W
Protective layers composed of C, (WMo) C, (ZrNb) N, B ₄ C, hydrogen-containing carbon and the like, and 16 and 16 ′ are lubricating layers composed of perfluoroalkyl polyether and the like. Setting the remanent magnetization film thickness product of the medium to 10 G · μm or more and 150 G · μm or less and the coercive force to 1600 Oe or more and 4000 Oe or less means the substrate temperature, the type of sputtering gas such as He, Ne, Ar, Kr, and Xe, the gas pressure, This is achieved by optimizing the input power during sputtering according to the composition and film configuration.

All the media shown in this embodiment have a remanent magnetization film thickness product of 10 G · μm or more and 150 G · μm or less and a coercive force of 16 μm.
The condition of not less than 00 Oe and not more than 4000 Oe is satisfied.

A substrate 11 made of a tempered glass substrate (Corning 0313) having an outer diameter of 95 mmφ is used.
25 nm of Cr was formed as the conductive films 12 and 12 'by the DC magnetron sputtering method under the film forming conditions of the r gas pressure of 1.7 mTorr and the input power density of 5 W / cm ² . Next, the substrate temperature is 300 ° C. and the Ar gas pressure is 1.
7mTorr, DC bias voltage from -100V to -400
The non-magnetic underlayers 13 and 13 'are changed to C by using the DC magnetron sputtering method (DC bias application) under the film forming condition of the applied power density of 5 W / cm ² while varying the V range.
r is 250 nm, and Co-16 is used as the magnetic layers 14 and 14 '.
At% Cr-4 at% Ta was sequentially formed in a thickness of 25 nm. At this time, a conductive jig is brought into contact with the surfaces of the conductive films 12 and 12 ', and the nonmagnetic underlayers 13 and 13' and the magnetic layer 1 are contacted.
A DC bias voltage was applied to the laminated surface of 4, 14 '. Finally, as protective layers 15 and 15 ', C is 10 nm
After the film formation, the 3 nm perfluoroalkyl polyether-based lubricating layers 16 and 16 'were formed.

As the medium of Comparative Example 1, a medium as shown in FIG. 2 was produced under the same conditions except that the conductive film was not provided and the bias was 0 V under the film forming conditions of the example.

Here, comparing the medium structures of FIG. 1 and FIG. 2, in the medium shown in FIG.
3, 13 ', magnetic layers 14, 14', and protective layers 15, 1
It can be seen that the area of 5'is smaller. This is because the jig was brought into contact with the conductive film at the outer peripheral portion, so that the film after the conductive film could not be laminated on the outer peripheral portion. In addition to this, as a method for ensuring electrical continuity between the conductive film and the substrate electrode, the conductive film may be contacted at the inner peripheral portion or may be contacted with the conductive film around the side surface of the substrate. Further, regarding the contact area, it can be easily inferred that point contact may be sufficient without contacting the entire circumference of the disk.

FIG. 3 shows the coercive force of the media produced as Example 1 and Comparative Example 1. The coercive force is increased by applying the DC bias voltage, and the coercive force shows the maximum value when the bias of -200V is applied. Further, when the bias is increased in the "-" direction, the coercive force becomes smaller, and when a bias of -400 V is applied, the coercive force becomes as low as that of a medium to which no bias is applied.
From the above, the range to apply the bias is -400V
As described above, it is understood that the voltage of less than −30V is preferable.

The composition of the magnetic film was changed to Co-14 at% Cr-6 at% under the same film forming conditions as the medium of this embodiment.
Ta, Co-18 at% Cr-8 at% Pt, Co-3
0 at% Ni-5 at% Pt, Co-20 at% Ni-
10 at% Cr, Co-16 at% Si-6 at% T
a, Co-20 at% Si-10 at% Pt, Co-1
5 at% Cr-4 at% Ta-4 at% B, Co-16
Even if it was changed to at% Cr-8 at% Pt-4 at% B, similar results were obtained although there were some differences in the absolute value of the coercive force. After forming the conductive films 12 and 12 ',
Once a thin oxide layer was formed on the surface of the conductive film by breaking the vacuum and exposing it to the atmosphere, the coercive force was improved by about 100 to 400 Oe. Further, similar results were obtained when the bias was applied only during the formation of the magnetic layer, but when the bias was applied only during the formation of the underlayer, the coercive force was not improved and the effect of the bias was hardly seen. There wasn't.

Example 2 A 2.5-inch canasite (crystallized glass) substrate was used as a substrate to prepare a multilayer magnetic recording medium having the structure shown in FIG. The substrate temperature was room temperature, the Xe gas pressure was 1.7 mTorr, and the input power density was 5 W / cm ^{2 under} the film forming conditions using the DC magnetron sputtering method, and Cr was deposited to 50 nm as the conductive films 42 and 42 ′. Next, the substrate temperature is 300 ° C and the Xe gas pressure is 1.7 mTorr.
, DC bias voltage was changed in the range of -100V to -400V, and the applied power density was DC magnetron sputtering method (DC bias application) under the film forming condition of 5W / cm ^2.
By using Cr-15 as the non-magnetic underlayer 43, 43 '.
At% Ti was formed in a thickness of 150 nm, and Co-19 at% Cr-8 at% Pt was formed in a thickness of 12 nm as the first magnetic layers 44 and 44 '. Further, Cr-1 is used as the non-magnetic intermediate layer 45, 45 '.
5 at% Ti was deposited to 2 nm, and Co-19 at% Cr-8 at% Pt was deposited to 12 nm as the second magnetic layers 46 and 46 'to form a medium structure having two magnetic layers. Finally protective layer 4
After forming hydrogen-containing carbon to a thickness of 10 nm as 7,47 ', lubricating layers 48 and 48' of 3 nm of perfluoroalkylpolyether type were formed.

In the same manner as in Example 1, a medium was prepared under the same conditions as Comparative Example 2 except that no conductive film was provided and the bias was 0 V under the film forming conditions of Example.

FIG. 5 shows the coercive force of the media prepared as Example 2 and Comparative Example 2. This result was similar to that of Example 1, and it was found that the medium to which the bias was applied had a higher coercive force. The number of magnetic layers is 3
Similar results were obtained by changing the number of layers, 4 layers, and 5 layers.
Further, similar results were obtained when the compositions of the magnetic layers were not the same but were changed independently.

(Embodiment 3) With respect to the media of Embodiments 1 and 2, at least a part of the magnetic poles is a recording-only magnetic head using a magnetic material having a saturation magnetic flux density of 1.2 T or more, and a giant magnetic resistance. The electromagnetic conversion characteristics were measured by combining a read-only magnetic head utilizing the effect. The measurement conditions are a linear recording density of 180 kFCI and a track width of 2 μm.
m, the gap length of the recording head was 0.2 μm, the shield interval of the reproducing head was 0.2 μm, and the flying height of the slider of the magnetic head was 0.04 μm. The S / N (signal-to-noise ratio) measured under these conditions was 35 dB, which was the highest in the medium produced by applying a bias of -200 V, which had the highest coercive force in the medium of Example 1. With other media, 32 dB could be secured. Example 2
The medium having the highest coercive force was also the highest in the medium (4), and the medium produced by applying a bias of -200 V was the highest, and was 38 dB. 33 dB could be secured for other media. It can be said that the magnetic recording medium of the present invention has a sufficient electromagnetic conversion characteristic, considering that the required S / N for operating the device normally is about 30 dB. The reason that the medium of Example 2 could have a better S / N than the medium of Example 1 was that the noise was significantly smaller. However, in consideration of actual mass production, it is not necessary to intentionally increase the specifications to raise the cost, and it is preferable to use a medium having a structure that is inexpensive and conforms to the specifications.

(Embodiment 4) FIG. 6A is a top view of an example of the magnetic memory device of the present invention, and FIG.
It shows in (b). The magnetic recording medium 61 is held by a holder connected to the magnetic recording medium driving unit 62, and the magnetic recording medium 61 is held.
The magnetic head 63 is arranged so as to face each surface of the. The signal reproduced by the magnetic head 63 is waveform-processed by the recording / reproducing signal processing system 64. In the reproducing waveform of the head utilizing the giant magnetoresistive effect, the positive and negative magnitudes become asymmetric due to the problem peculiar to the head element, and it is necessary to repair this. Further, it is important to construct a signal processing circuit having an extremely low error rate by passing the restored signal through a signal processing LSI by maximum likelihood decoding. These waveform processing is performed by the recording / reproducing signal processing system 64. The magnetic head 63 is stably floated at a flying height of 0.05 μm or less, and the head is driven by a magnetic head drive unit 65 to a desired track with a head positioning accuracy of 0.4 μm or less. By combining the above components, it was possible to realize a high-density magnetic storage device having a storage capacity three times or more that of the conventional one. Further, even if the signal processing circuit for maximum likelihood decoding and the circuit for correcting the asymmetry of the reproduction signal of the magnetic head utilizing the giant magnetoresistive effect are removed from the recording / reproducing signal processing system 64, the storage capacity is more than twice that of the conventional one. A magnetic storage device having a capacity could be realized.

In the above embodiments, an example of a disk-shaped magnetic recording medium and a magnetic storage device using the same was described. However, the present invention is a tape-shaped or card-shaped medium having a magnetic layer only on one side, and It can also be applied to a magnetic storage device using this.

[0035]

According to the magnetic recording medium of the present invention, a conductive film is formed in advance on a medium using a non-conductive substrate, and then contact between the conductive film and the substrate electrode is ensured to form a DC bias. By sequentially forming the underlayer and the magnetic layer while applying a voltage, it is possible to improve the electromagnetic conversion characteristics that have a high coercive force and are compatible with high density recording. The present invention can also be applied to a multilayer magnetic recording medium in which a magnetic layer is divided by a non-magnetic intermediate layer. Furthermore, this magnetic recording medium and a magnetic head dedicated to recording using a magnetic material having a saturation magnetic flux density of 1.2 T or more in at least a part of the magnetic pole,
A magnetic head dedicated to reproduction that uses the giant magnetoresistive effect, a signal processing circuit using maximum likelihood decoding, and a circuit that corrects the asymmetry of the playback signal of the magnetic head that utilizes the giant magnetoresistive effect are combined to fly the slider of the magnetic head. Height to 0.
By making the thickness below 05 μm, high-quality playback output,
In addition, an extremely low error rate can be obtained, and a large-capacity and high-density magnetic storage device can be obtained as compared with a conventional magnetic storage device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a cross-sectional structure of a magnetic recording medium of the present invention.

FIG. 2 is an explanatory diagram showing a cross-sectional structure of a conventional magnetic recording medium.

FIG. 3 is an explanatory diagram comparing the coercive force of the magnetic recording medium of the present invention with that of a conventional magnetic recording medium.

FIG. 4 is an explanatory diagram showing a cross-sectional structure of a magnetic recording medium of the present invention.

FIG. 5 is an explanatory diagram comparing the coercive force of the magnetic recording medium of the present invention with that of a conventional magnetic recording medium.

FIG. 6 is an explanatory diagram showing a top surface and a cross-sectional structure of a magnetic memory device of the present invention.

[Explanation of symbols]

11 ... Non-conductive substrate, 12, 12 '... Conductive film, 13, 1
3 '... non-magnetic underlayer, 14, 14' ... Co-based alloy magnetic layer, 15, 15 '... protective layer, 16, 16' ... lubricating layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaaki Ninomoto 1-280 Higashi Koikekubo, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Nobuyuki Inaba 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central Research Laboratory

Claims (15)

[Claims] 1. A medium in which a conductive film is previously formed on a non-conductive substrate, and a magnetic layer is laminated directly or through a non-magnetic underlayer while applying a DC bias voltage to the conductive film, The thickness of the magnetized film is 10G ・ μm or more and 150G ・
A magnetic recording medium having a coercive force of 1600 Oe or more and 4000 Oe or less. 2. The magnetic recording medium according to claim 1, wherein there is a region where the magnetic layer is not partially laminated on an inner peripheral portion or an outer peripheral portion of the medium. 3. The conductive film according to claim 1, wherein the conductive film wraps around a side surface of an inner peripheral portion or an outer peripheral portion of the medium,
A magnetic recording medium having a region which is not partially laminated on the magnetic layer at this portion. 4. A conductive film is previously formed on a non-conductive substrate, and a magnetic layer is laminated directly or with a non-magnetic underlayer on the conductive film while applying a DC bias voltage, and further on this. A magnetic recording medium, which is a medium in which a protective layer is laminated, characterized in that there is a region where the magnetic layer is not partially laminated in an inner peripheral portion or an outer peripheral portion of the medium. 5. The magnetic recording medium according to claim 4, wherein the conductive film wraps around a side surface of an inner peripheral portion or an outer peripheral portion of the medium, and there is a region which is not partially laminated on the magnetic layer at this portion. . 6. The magnetic recording medium according to claim 4, wherein the sputter gas concentration of Ar, Kr, Xe or the like in the magnetic layer is higher than that in the protective layer. 7. The magnetic recording according to claim 4, wherein the interplanar spacing of the Co (110) plane parallel to the film plane is larger than the interplanar spacing of the Co (110) plane inclined by 20 degrees or more from the film plane. Medium. 8. The oxide film, the nitrogen-containing layer, or the carbon-containing layer having a thickness of about 0.1 nm to 10 nm is formed on the surface of the conductive film according to claim 1, 2, 3, 4, 5, 6 or 7. Magnetic recording medium. 9. The conductive film according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein C, Ti, V, Cr, Cu,
Zn, Nb, Mo, Ru, Rh, Pd, Ag, Ta,
A magnetic recording medium containing, as a main component, at least one selected from W, Pt, Au, Ni-P, and Cr-P. 10. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, in 9, the Ar, Kr,
A magnetic recording medium in which the concentration of sputtering gas such as Xe is lower than that in the magnetic layer. 11. Claims 1, 2, 3, 4, 5, 6, 7,
8. A magnetic recording medium having a multilayer structure according to 8, 9 or 10 in which the magnetic layer is divided by a non-magnetic intermediate layer. 12. Claims 1, 2, 3, 4, 5, 6, 7,
8, 9, 10 or 11, a drive unit for driving the magnetic recording medium in the recording direction, a magnetic head arranged to face each surface of the magnetic recording medium, and the magnetic head for the magnetic recording medium. And a recording / reproducing signal processing system for waveform-processing an input signal to the magnetic head and an output signal from the magnetic head. 13. The magnetic storage device according to claim 12, wherein the magnetic head is a recording / reproducing separated type head in which an inductive magnetic head dedicated to recording and a magnetic head utilizing a magnetoresistive effect dedicated to reproducing are combined. 14. The induction type magnetic head for recording only, wherein at least a part of the magnetic pole is made of a magnetic material having a saturation magnetic flux density of 1.2 T or more, and reproduction only using the magnetoresistive effect. A magnetic storage device using the recording / reproducing separated type head in combination with the magnetic head of. 15. The method according to claim 12, 13 or 14,
A magnetic storage device in which a signal processing circuit by maximum likelihood decoding and a circuit for correcting an asymmetry of a reproduction signal of a magnetic head using a giant magnetoresistive effect are combined to set a flying height of a slider of the magnetic head to 0.05 μm or less.