JPH07254118A - Magnetoresistive head and magnetic recording / reproducing apparatus - Google Patents

Abstract

(57) [Summary] [Object] To provide a magnetoresistive effect magnetic head exhibiting high sensitivity and excellent soft magnetic characteristics, and having a simple manufacturing process. [Structure] As a magnetoresistive material, an exchange bias magnetic field from an antiferromagnetic layer 16 is applied to a magnetic layer 15 to form a magnetic layer 13.
Directly, in a magnetoresistive head using a multilayer film that does not apply the exchange bias magnetic field from the antiferromagnetic layer 16, a highly corrosion-resistant antiferromagnetic layer 1 containing oxide as a main component.
6 is the magnetic layer 13 when viewed from the substrate 11 on which the multilayer film is formed,
It was formed on the side farther than 15. Moreover, after forming the electrode 17, a multilayer film was formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head using a multilayer magnetoresistive film having a high magnetoresistive effect,
And a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art With the increase in density of magnetic recording, a material having high sensitivity is required as a magnetoresistive effect material used for a reproducing magnetic head. Recently, Physical Review B, Vol. 43, No. 1, 1297
~ Giant Magnetoresistance in Soft Ferromagnetic Films on page 1300
A method of separating two magnetic layers by a non-magnetic layer and applying an exchange bias magnetic field from an antiferromagnetic layer to one of the magnetic layers has been devised as in "Magnetic Multilayers)". Since the thickness of one magnetic layer is thin in this multilayer film, the demagnetizing field coefficient when the magnetoresistive effect element is formed is small, and therefore, the magnetoresistive effect is exhibited in a low magnetic field. Also, the amount of change in magnetic resistance is large.

[0003]

The multilayer film described in the above document uses an antiferromagnetic layer made of a Fe--Mn alloy. However, the Fe-Mn-based alloy has poor corrosion resistance and deteriorates the reliability of the magnetoresistive effect element using the multilayer film. Therefore, a multilayer film using a Ni—O antiferromagnetic material having excellent corrosion resistance can be considered. However, the magnetic layer formed on the Ni—O-based antiferromagnetic layer deteriorates in soft magnetic characteristics, and reduces the sensitivity of the magnetoresistive effect element. Therefore, if a Ni—O-based antiferromagnetic layer is formed on the magnetic layer, the soft magnetic characteristics of the magnetic layer are improved, but the Ni—O-based antiferromagnetic layer has a high electric resistivity and an electrode is formed on the multilayer film. Even if formed, a sense current cannot flow.

An object of the present invention is to provide a means for solving the problem of a magnetoresistive head using a multilayer film.

[0005]

The inventors of the present invention have conducted extensive studies on magnetoresistive heads having various structures using a multilayer film, and as a result, by forming a multilayer film after forming electrodes, They have found that a sensitive magnetoresistive head can be obtained, and completed the present invention.

That is, after forming the electrodes, a multi-layer film having two magnetic layers and a non-magnetic layer separating them and one magnetic layer in contact with the antiferromagnetic layer is formed.

For the antiferromagnetic layer, a highly corrosion-resistant material containing an oxide as a main component is used. Further, the antiferromagnetic layer is formed on the side farther from the two magnetic layers as viewed from the substrate on which the multilayer film is formed. Furthermore, by forming a high coercive force layer made of a Co-based alloy between the substrate and the electrode, a magnetoresistive head having less Barkhausen noise can be obtained. Further, in order to use the magnetoresistive head in the magnetic recording / reproducing apparatus, it is preferable to combine an inductive magnetic head.

[0008]

As described above, the high corrosion-resistant antiferromagnetic layer containing an oxide as a main component is used as described above when viewed from the substrate on which the multilayer film is formed.
By forming the layer on the side farther than the magnetic layer, the soft magnetic characteristics of the magnetic layer are improved. Further, by forming the multilayer film on the electrode, the multilayer film and the electrode can be electrically contacted with each other. Further, by forming a high coercive force layer made of a Co-based alloy between the substrate and the electrode, it becomes possible to apply a bias magnetic field to the magnetic layer forming the multilayer film,
As a result, Barkhausen noise that is likely to occur in the magnetoresistive head can be suppressed. Further, by combining the magnetoresistive head and the induction magnetic head, a high-performance magnetic head suitable for high-density magnetic recording can be obtained, and as a result, the performance of the magnetic recording / reproducing apparatus is significantly improved.

[0009]

【Example】

[Example 1] An ion beam sputtering method was used for forming the multilayer film. The ultimate vacuum is 3/10 ⁵ Pa, and the Ar pressure during sputtering is 0.02 Pa. Also,
The film formation rate is 0.01 to 0.02 nm / s.

The cross-sectional structure of the multilayer film is shown in FIG. As shown in the figure, in this example, two types of multilayer films were formed. First,
As shown in FIG. 2A, an antiferromagnetic layer 22 made of Ni—O having a thickness of 50 nm is formed on a substrate 21 made of Si100.
Was formed. The antiferromagnetic layer 22 is formed by using a target made of NiO, but it is considered that the composition ratio of Ni and oxygen is changed by the sputtering. Even if the composition ratio of Ni and oxygen changes, Ni-
If the O-based layer exhibits antiferromagnetism at room temperature, it can be used as an antiferromagnetic material in a multilayer film. Further, the antiferromagnetic layer 22
On top of this, a multilayer film was formed in which magnetic layers 23 and 25 of Ni-20 at% Fe having a thickness of 5.0 nm and a non-magnetic layer 24 of Cu having a thickness of 2.5 nm were laminated.

Further, as shown in FIG. 2B, a Ni-20 at thickness of 5.0 nm is formed on a substrate 26 made of Si100.
% Fe magnetic layers 27 and 29, thickness 2.5 nm
After forming the non-magnetic layer 28 made of Cu, a thickness of 50 n
A multi-layered film was formed by laminating the antiferromagnetic layer 30 of m-Ni-O system.

That is, in the multilayer film shown in FIG.
An antiferromagnetic layer is formed on the side closer to the two magnetic layers when viewed from the substrate on which the multilayer film is formed. In contrast, Figure 2
In the multilayer film shown in (b), the antiferromagnetic layer is formed on the side farther from the two magnetic layers when viewed from the substrate on which the multilayer film is formed.

Magnetization curves of the multilayer film having the structure shown in FIGS. 2A and 2B are shown in FIGS. 3A and 3B, respectively. Physical Review B (Pysical Revi)
ew B), Vol. 43, No. 1, pp. 1297-1300, due to the magnetization reversal of the magnetic layer not in contact with the antiferromagnetic layer, a zero as shown in FIGS. A rapid change in magnetization occurs near the magnetic field. On the other hand, since the magnetic layer in contact with the antiferromagnetic layer receives the exchange bias magnetic field from the antiferromagnetic layer, the magnetic field for magnetization reversal is 8
It is shifted from the zero magnetic field by about kA / m.

In the magnetoresistive head, the external magnetic field is detected by reversing the magnetization of the magnetic layer that is not in contact with the antiferromagnetic layer. Therefore, the magnetic characteristics of the magnetic layer that is not in contact with the antiferromagnetic layer are important.

As shown in FIG. 3A, in the multilayer film having the structure shown in FIG. 2A, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 320 A / m. On the other hand, as shown in FIG. 3B, in the multilayer film having the structure shown in FIG. 2B, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 160 A / m. It is half the value of the multilayer film shown in.

In the multilayer film having the structure shown in FIG. 2 (a),
The reason why the coercive force of the magnetic layer not in contact with the antiferromagnetic layer becomes high is presumed as follows. That is, an antiferromagnetic layer is previously formed under the two magnetic layers. Since this antiferromagnetic layer has a large thickness, unevenness is generated on the upper surface. Therefore, it is considered that the flatness of the magnetic layer formed on the antiferromagnetic layer deteriorates and the coercive force of the magnetic layer increases.
On the other hand, in the multilayer film having the structure shown in FIG. 2B, since the magnetic layer is formed on the flat substrate, the magnetic layer has flatness and is considered to have excellent soft magnetic characteristics. Also,
By the way, the magnetoresistive change rate of the multilayer film having the structure shown in FIG. 2B was 3.3%.

The difference in the coercive force of the magnetic layer due to the structure of the above-mentioned multilayer film is that the magnetic layer has a thickness of 5.0 nm of Ni-16a.
It was even larger when the t% Fe-18at% Co alloy was used. That is, in the multilayer film having the structure shown in FIG. 2A, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 8
In the multilayer film having the structure shown in FIG. 2B, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 160 A / m.
It was A / m. As described above, the difference in the coercive force of the magnetic layer due to the structure of the above-described multilayer film is broadly varied between Ni-Fe system and Ni- system.
Observed in Fe-Co based magnetic materials.

The difference in the coercive force of the magnetic layer due to the structure of the above-mentioned multilayer film is the same even when another oxide type is used as the antiferromagnetic layer. Other oxide-based antiferromagnetic materials are Co-
O-based, Fe-O-based, Ni-Co-O-based, etc. can be used. However, the Ni—O system, which has a high Neel temperature, is the most preferable antiferromagnetic material. As described above, the multilayer film having the structure shown in FIG. 2B has excellent soft magnetic characteristics. Therefore, a magnetoresistive effect element was manufactured using the multilayer film having the structure shown in FIG.

FIG. 1 shows the structure of the manufactured magnetoresistive effect element. Glass was used for the substrate 11. First, the electrode 17 was formed on the substrate 11. In this embodiment, the electrode 1
Au was used as the material of No. 7. A multilayer film was formed after the electrodes were formed. The buffer layer 12 in the multilayer film has a thickness of 5.
0 nm Hf was used. The buffer layer 12 has a function of improving soft magnetic characteristics and heat resistance of the multilayer film.
Further, the Ni-20 at% Fe having a thickness of 5.0 nm is the magnetic layers 13 and 15, and the Cu having a thickness of 2.5 nm is the non-magnetic layer 1.
4, Ni-O having a thickness of 50 nm was used as the antiferromagnetic layer 16.

Since the multilayer film is formed after the electrodes are formed as shown in FIG. 1, the multilayer film is also formed on the electrodes. Due to the shape of the electrode 17, as shown in FIG. 1, the magnetic layer of the multilayer film on the electrodes and the magnetic layer of the multilayer film between the electrodes are magnetically separated. In this case, since the external magnetic field is detected only by the multilayer film between the electrodes, the effective track width can be narrowed. Since the multilayer film used in the present invention is used in a magnetoresistive head of a later generation than the permalloy single layer film, the track width is considered to be 1 μm or less. Therefore, it is desirable to magnetically separate the multilayer magnetic layer on the electrodes from the multilayer magnetic layer between the electrodes.

Further, the magnetoresistive effect element of the present invention has a simple manufacturing process. Therefore, the cost for mass production is low. Since a small-sized magnetic disk device for individuals needs to reduce the production cost as much as possible, it is preferable to use a magnetic head that can be formed by the simple process as in this embodiment even if the performance is slightly lowered.

When the output of the magnetoresistive effect element of the present invention was measured, the magnetoresistive effect element of the present invention was 2.1 in comparison with the conventional magnetoresistive effect element using a permalloy single layer film.
The output was twice as high.

In this embodiment, Cu is used as the non-magnetic layer, but similar results can be obtained by using Au, Ag, and Al, which have low electric resistivity.

Although Hf is used as the buffer layer 12 in this embodiment, the same effect as that of the above embodiment can be obtained as long as it is a non-magnetic alloy containing Hf as a main component.
Further, the buffer layer material is preferably Ti, Zr, Ta, Nb, or an alloy containing these as the main components. This is because when the buffer layer material is Hf, Ti, Zr, Ta, Nb, or an alloy containing these as the main components, the magnetic layer has a strong (111) orientation, and even if the magnetic layer is thin, excellent soft magnetic properties are obtained. This is because the characteristics can be obtained.

Example 2 By the same method as in Example 1, the multilayer film shown in FIG. 4 was formed. As shown in the figure, also in this example, two types of multilayer films were formed. First, FIG.
As shown in (a), a 50-nm-thick Ni—O-based antiferromagnetic layer 42 was formed on a substrate 41 made of Si100. Furthermore, a thickness of 3.0 nm is formed on the antiferromagnetic layer 42.
Magnetic layer 43 of Ni-20 at% Fe, thickness 2.
Magnetic layer 44 consisting of 0 nm Co, 2.5 nm thick C
a non-magnetic layer 45 made of u, a magnetic layer 46 made of Co having a thickness of 1.0 nm, and Ni-20 at% Fe having a thickness of 4.0 nm.
A multi-layered film was formed by laminating the magnetic layer 47 consisting of.

Further, as shown in FIG. 4 (b), a Ni-20at film having a thickness of 4.0 nm is formed on a substrate 51 made of Si100.
% Magnetic layer 52 made of Fe, magnetic layer 53 made of Co having a thickness of 1.0 nm, non-magnetic layer made of Cu having a thickness of 2.5 nm, magnetic layer 55 made of Co having a thickness of 2.0 nm, thickness Magnetic layer 5 made of Ni-20 at% Fe of 3.0 nm
6, antiferromagnetic layer 57 made of Ni-O system having a thickness of 50 nm
To form a multilayer film.

In the multilayer film shown in FIG. 4A, an antiferromagnetic layer is formed on the side closer to the two magnetic layers as seen from the substrate on which the multilayer film is formed. On the other hand, in the multilayer film shown in FIG. 4B, the antiferromagnetic layer is formed on the side farther than the two magnetic layers when viewed from the substrate on which the multilayer film is formed.

As shown in FIG. 5A, in the multilayer film having the structure shown in FIG. 4A, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 640 A / m. On the other hand, as shown in FIG. 5B, in the multilayer film having the structure shown in FIG. 4B, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer is 160 A / m. It becomes 1/4 of the value in the multilayer film shown in. In addition, the magnetoresistive change rate of the multilayer film having the structure shown in FIG. 4B is 5.7.
% Met.

When the magnetoresistive effect element having the structure shown in FIG. 1 was manufactured using the multilayer film having the structure shown in FIG. 4B, it was compared with the conventional magnetoresistive effect element using the permalloy single layer film. The magnetoresistive element of the present invention showed a 3.1 times higher output.

Example 3 A magnetoresistive effect element having a structure similar to that of Example 1 was formed. FIG. 6 shows the structure of the magnetoresistive effect element. Glass was used for the substrate 61. Cu was used for the electrode 67, and a magnetic layer 68 made of Co-17 at% Pt was formed between the electrode 67 and the substrate 61. The buffer layer 62 in the multilayer film has a thickness of 5.
0 nm Hf was used. In addition, the thickness of Ni is 5.0 nm.
-20 at% Fe in magnetic layers 63 and 65, thickness 2.5
nm Cu to the non-magnetic layer 64, thickness 50 nm Ni-O
Was used as the antiferromagnetic layer 66. Also, Co-17 at% Pt
The magnetic layer 68 made of is a high coercive force material having a coercive force of about 80 kA / m. This was formed in order to apply a bias magnetic field in the track width direction of the magnetic layer 63. By applying a bias magnetic field to the magnetic layer 63, Barkhausen noise of the magnetoresistive effect element of the present invention was suppressed.

For the magnetic layer 68, another high coercive force material can be used. A material having a small layer thickness and high coercive force is preferable, and many Co-based alloys have such a material. Co-based alloys include Co-Ta-Pt, Co-Cr-Pt, Co-Cr
Are preferred.

Further, the magnetoresistive effect element shown in FIG. 7 was formed. Glass was used for the substrate 71. Buffer layer 7
For No. 2, Nb with a thickness of 5.0 nm was used. Also, thickness 5.
0 nm of Ni-20 at% Fe was added to the magnetic layers 73 and 7.
5, Cu of 2.5 nm thickness is non-magnetic layer 74, thickness of 50 n
The Ni-O of m was used as the antiferromagnetic layer 76. Also, the electrode 77
Cu was used for. The electrode 77 has a slight taper unlike the magnetoresistive effect element according to the first embodiment. The magnetoresistive effect element shown in FIG. 7 showed substantially the same characteristics as the magnetoresistive effect element shown in FIG. 1 described in the first embodiment.

Further, as in the magnetoresistive effect element shown in FIG. 8, by forming the high coercive force layer 88 between the electrode 87 and the substrate 81, a bias magnetic field is applied to the magnetic layer 83 and Barkhausen noise is generated. Suppressed.

Example 4 A magnetic head was manufactured using the magnetoresistive effect element of the present invention. The structure of the magnetic head is shown below.

FIG. 9 is a perspective view when a part of the recording / reproducing separated type head is cut. A sintered body containing Al ₂ O ₃ .TiC as a main component was used as the substrate 97 for the slider. Board 9
A shield layer 92 made of a Ni-20 at% Fe alloy was formed on No. 7 by a sputtering method. Shield layer 92
Had a thickness of 1.0 μm. After forming a gap layer made of Al ₂ O _{3 having a} layer thickness of 0.1 μm on the shield layer 92 by the sputtering method, the magnetoresistive effect made up of the multilayer magnetoresistive effect film 91 and the electrode 98 is made by the process described in the first embodiment. The device was formed.

The multilayer magnetoresistive effect film 91 is formed of Ni--O (5
0 nm) / Ni-20 at% Fe (3.0 nm) / Co
(2.0 nm) / Cu (2.5 nm) / Co (1.0 n)
m) / Ni-20 at% Fe (4.0 nm) / Hf (5.
0 nm) was used. In addition, the electrode 98 contains Cr / Cu /
A multi-layered material called Cr was used.

In this embodiment, the electrode interval is 1.0 μm. The width of the multilayer magnetoresistive effect film 91 (length in the direction normal to the surface of the magnetic recording medium) is 1.0 μm. further,
After forming a gap layer similar to the above-mentioned gap layer, Ni-2 having a thickness of 1.0 μm is formed by a sputtering method.
A shield layer 93 made of a 0 at% Fe alloy was formed.
The part described above functions as a reproducing head.

Next, after forming a gap layer of Al ₂ O _{3 having} a thickness of about 3 μm, a recording head composed of a lower magnetic pole 95, an upper magnetic pole 96 and a coil 94 was formed. For the lower magnetic pole 95 and the upper magnetic pole 96, a Ni-20 at% Fe alloy having a film thickness of 3.0 μm formed by a sputtering method was used. The gap layer between the lower magnetic pole 95 and the upper magnetic pole 96 has a thickness of 0.2 μm and is formed by sputtering.
1 ₂ O ₃ was used. Cu having a film thickness of 3 μm was used for the coil 94.

After all the steps such as polishing in the magnetic head manufacturing process are performed, the magnetic head is heat-treated at 230 ° C. for 10 minutes in a magnetic field of 400 kA / m to form Ni--
The direction of the exchange bias magnetic field of the O-based antiferromagnetic layer was set to the direction normal to the surface of the magnetic recording medium. Further, the easy magnetization direction of the magnetic layer not in contact with the Ni—O antiferromagnetic layer is a direction orthogonal to the direction of the exchange bias magnetic field of the antiferromagnetic layer.

A recording / reproducing experiment was conducted with the magnetic head having the above-described structure. The sense current flowing through the magnetoresistive element is 3 ×
It was set to 10 ⁷ A / cm ² . Furthermore, Ni-F with a thickness of 30 nm
A magnetic head using a single-layer film was produced and the output was compared with that of the magnetic head of the present invention.
The reproduction output was 3.2 times higher. It is considered that this is because the reproducing head of the present invention uses a multilayer film having a high magnetoresistive effect.

A magnetic head using the multilayer film described in the embodiment 1 shown in FIG. 2A was also manufactured. As with the magnetoresistive head of the present invention, the output is high, but Barkhausen noise is generated. It was observed very often. In addition, distortion was observed in the output waveform. It is considered that this is because the coercive force of the multilayer film described in Example 1 shown in FIG. On the contrary, in the magnetoresistive head of the present invention, Barkhausen noise was not frequently observed, and no distortion was observed in the output waveform. It is considered that the coercive force of the magnetic layer is low because the Ni—O antiferromagnetic layer is formed on the upper part of the.

When a magnetic head was manufactured using the magnetoresistive effect element having the structure shown in FIG. 6, a magnetic head having good characteristics without showing Barkhausen noise could be obtained.

[Embodiment 5] Using the magnetic head of the present invention described in Embodiment 4, a magnetic disk device was manufactured. Figure 10
A schematic diagram of the structure of the magnetic disk device is shown in FIG.

For the magnetic recording medium 101, a material made of a Co-Ni-Pt-Ta alloy having a residual magnetic flux density of 0.75T was used. The track width of the recording head of the magnetic head 103 was 1 μm, and the track width of the reproducing head was 1 μm.
Since the magnetoresistive effect element in the magnetic head 103 exhibits an output about three times that of a conventional magnetoresistive effect element using a permalloy single layer film, it is particularly suitable for a magnetic recording / reproducing apparatus having a recording density of 1 Gb / in ² or more. It is valid. Also, 10 Gb
It is considered essential for a magnetic recording / reproducing apparatus having a recording density of / in ² or more.

[0045]

According to the present invention, even if a highly corrosion-resistant antiferromagnetic layer containing an oxide as a main component is formed on the side farther than the two magnetic layers when viewed from the substrate on which the multilayer film is formed. A sense current can be passed through the multilayer film, and a magnetoresistive head having high sensitivity and excellent soft magnetic characteristics can be obtained. Further, it is possible to obtain a magnetoresistive head having less Barkhausen noise. Further, it is possible to obtain a high performance magnetic head advantageous for a high density magnetic recording / reproducing apparatus.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetoresistive effect element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a multilayer film.

FIG. 3 is a characteristic diagram showing changes in a magnetization curve due to the structure of a multilayer film.

FIG. 4 is a cross-sectional view showing the structure of a multilayer film.

FIG. 5 is a characteristic diagram showing changes in a magnetization curve due to the structure of a multilayer film.

FIG. 6 is a sectional view of a magnetoresistive effect element according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a magnetoresistive effect element according to a third embodiment of the present invention.

FIG. 8 is a sectional view of a magnetoresistive effect element according to a fourth embodiment of the present invention.

FIG. 9 is a perspective view of a magnetic head using the magnetoresistive effect element of the present invention.

FIG. 10 is an explanatory diagram of a magnetic recording / reproducing apparatus of the present invention.

[Explanation of symbols]

11 ... Substrate, 12 ... Buffer layer, 13, 15 ... Magnetic layer,
14 ... Nonmagnetic layer, 16 ... Antiferromagnetic layer, 17 ... Electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Hoshino 1-280, Higashi Koigokubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] 1. A multi-layered film having two magnetic layers and a non-magnetic layer separating them, one magnetic layer being in contact with an antiferromagnetic layer, and a pair of electrodes for flowing a sense current. In the magnetoresistive head, the multilayer film is formed after forming the electrodes, and the antiferromagnetic layer is formed on the side farther from the two magnetic layers when viewed from the substrate on which the multilayer film is formed. A magnetoresistive head, wherein the antiferromagnetic layer contains an oxide as a main component. 2. The magnetoresistive head according to claim 1, wherein the magnetic layer of the multilayer film on the electrode is separated from the magnetic layer of the multilayer film between the electrodes. 3. The magnetoresistive head according to claim 1, wherein a magnetic layer made of a Co-based alloy is formed between the pair of electrodes and the substrate. 4. The magnetoresistive head according to claim 1, 2 or 3, comprising the magnetoresistive head and the two magnetic shield layers. 5. A composite magnetic head according to claim 4, wherein the magnetoresistive head and the inductive magnetic head are combined. 6. The method according to claim 1, 2, 3, 4 or 5.
A magnetic recording / reproducing apparatus using the above magnetic head.