JPH07210828A - Magnetoresistive thin film magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] The coercive force of the hard magnetic film, which is the longitudinal bias layer, can be increased and the bias magnetic field can be supplied permanently, so that stable domain control can be performed and Barkhausen noise can be reduced. It is an object of the present invention to provide an MR effect type thin film magnetic head having high performance and high reliability. [Structure] Between the lower shield layer 3 and the upper shield layer 11, a lateral bias layer 5, a magnetoresistive layer 7, a hard magnetic layer 8,
A magnetoresistive thin film magnetic head including a read sensing portion having a lead layer 9 and the like, wherein a hard magnetic layer 8 has a multilayer structure of three or more layers in which ferromagnetic films and nonmagnetic films are alternately laminated. It has a structure which is the magnetic layer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect thin film magnetic head (hereinafter referred to as MR effect thin film magnetic head) used in a magnetic recording device such as a magnetic disk device.

[0002]

2. Description of the Related Art In recent years, magnetic resistance (M
The MR effect thin film magnetic head using the (R) effect has come to be used.

A conventional MR effect thin film magnetic head will be described below. Generally, in order for the MR effect layer to function stably as a reproducing head, it is necessary to apply two types of bias magnetic fields, that is, a lateral bias and a longitudinal bias. The lateral bias magnetic field is a bias magnetic field necessary to shift the operating point of the reproducing head to the most linear range of the RH characteristic curve, and is intended to maintain the linearity of the reproducing output. This lateral bias magnetic field is applied in a direction perpendicular to the surface of the magnetic recording medium and parallel to the surface of the MR effect layer.
There are various methods such as L bias.

On the other hand, the longitudinal bias magnetic field is applied in the direction parallel to the surface of the magnetic recording medium and parallel to the longitudinal direction of the MR effect layer, and by making the MR effect layer into a single domain, Barkhausen generated from the multi-domain action. It has the function of suppressing noise. Conventionally, this longitudinal bias magnetic field is roughly divided into two methods. One is, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-40610, a method of performing exchange coupling with an MR effect layer using an antiferromagnetic film such as FeMn, and the other is CoCrPt.
Is a method of ferromagnetically coupling or magnetostatically coupling a hard magnetic layer having a high coercive force, such as the MR effect layer, which is a soft magnetic film.
No. 213 publications.

As described above, no matter whether the antiferromagnetic film or the hard magnetic layer is used as the longitudinal bias, it is possible to reduce the Barkhausen noise by controlling the magnetic domain or domain wall of the MR effect layer. When magnetic domain control is performed using an antiferromagnetic film, the antiferromagnetic material is limited to substantially FeMn because of restrictions on magnetic properties such as blocking temperature.

[0006]

However, in the above conventional structure, when a hard magnetic layer is used as the longitudinal bias layer,
It is necessary to have a high coercive force that eliminates the decrease of the bias magnetic field and maintains the effect of controlling the magnetic domain permanently. In general hard magnetic layers such as CoCrTa film, in order to obtain this high coercive force, the Cr film, etc. However, there is a problem in that the film thickness of the hard magnetic layer is substantially increased due to this Cr film thickness, which is disadvantageous in the process. It is also reported that the addition of Pt can provide a high coercive force without an underlayer, but this requires very high flatness like a magnetic disk, and various processes such as resist processing are required. Is difficult to apply to an MR effect type thin film magnetic head, and because of lack of stability, the coercive force of the hard magnetic layer used for controlling magnetic domains of the MR effect type thin film magnetic head is generally about 1500 Oe, It had a problem that it lacked coercive force. Further, the above-mentioned JP-A-60-59.
In Japanese Patent No. 518, the magnetic domain control is performed by utilizing the ferromagnetic coupling between the MR effect layer and the hard magnetic layer. This ferromagnetic coupling reduces the coercive force specific to the hard magnetic layer, and thus the durability of the bias magnetic field is increased. It had a problem that it lacked. Further, in the above-mentioned JP-A-2-220213,
Although the magnetostatic coupling between the MR effect element and the hard magnetic layer is used by interposing the non-magnetic layer, it is difficult to completely suppress Barkhausen noise even in this method. Was.

The present invention solves the above problems of the prior art. Since the coercive force of the hard magnetic layer, which is the longitudinal bias layer, can be increased and the bias magnetic field can be supplied permanently, the magnetic domain control can be stably performed. It is an object of the present invention to provide a high-performance and highly-reliable MR effect type thin film magnetic head capable of reducing Barkhausen noise.

[0008]

In order to achieve this object, an MR effect thin film magnetic head according to a first aspect of the present invention has a lateral bias layer and a magnetic resistance between a lower shield layer and an upper shield layer. A magnetoresistive effect thin film magnetic head having a reproduction sensing part having an effect layer, a hard magnetic layer, a lead layer, etc., wherein the hard magnetic layer comprises three or more layers in which ferromagnetic films and nonmagnetic films are alternately laminated. The MR effect thin film magnetic head according to claim 2, wherein the hard magnetic layer is the lead layer side of the magnetoresistive effect layer and / or the upper shield layer. The MR effect thin film magnetic head according to claim 3, wherein the MR effect thin film magnetic head is formed in direct contact with the lead layer side, and the magnetoresistive effect layer and / or the hard magnetic layer according to claim 2. In contact with the upper shield layer Layer has a structure which is a ferromagnetic film, the MR effect type thin film magnetic head according to claim 4,
What is claimed is: 1. A magnetoresistive effect thin-film magnetic head comprising a reproducing sensing part having a lateral bias layer, a magnetoresistive effect layer, a hard magnetic layer, a lead layer, etc. between a lower shield layer and an upper shield layer, said hard magnetic layer. Is a single hard magnetic layer and is formed on the lead layer side of the upper shield layer via a non-magnetic film.

Here, the ferromagnetic film forming the hard magnetic layer having a multi-layered structure of three or more layers may be a CoCrPt film, a CoNi film, a CoCrTa film, or the like. Further, as the non-magnetic film, Ta, Ti, W or the like may be used instead of the Cr film. The number of ferromagnetic layers and the number of non-magnetic layers are required to be two or more when the ferromagnetic coupling and the magnetostatic coupling are used simultaneously. When the hard magnetic layer is provided only on the lead layer side of the upper shield layer, the hard magnetic layer may have a single layer structure in order to increase the coercive force of the hard magnetic layer. It is more effective to use magnetostatic coupling via a non-magnetic film between them.

[0010]

With this structure, the coercive force can be increased by forming the hard magnetic layer, which is the longitudinal bias layer, into a multilayer structure of three or more layers in which ferromagnetic films and nonmagnetic films are alternately laminated. It is possible to carry out stable and stable magnetic domain control. Further, by alternating the ferromagnetic film and the non-magnetic film, the portion where the ferromagnetic film is in direct contact with the MR effect layer is ferromagnetically coupled, and the ferromagnetic film via the non-magnetic layer is magnetostatically coupled. Magnetic domain control can be performed by both of them. Also,
Since the magnetic domain control is performed by providing the hard magnetic layer not only on the MR effect layer but also on the lead layer side of the upper shield layer, it is possible to suppress the generation of Barkhausen noise.

[0011]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an essential part of an MR effect thin film magnetic head in a first embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. 1 is Al ₂ O ₃
-Substrate made of ceramic material such as TiC, 2 is Al
_An insulating layer made of ₂ O ₃ , SiO _2, etc., 3 is a lower shield layer made of a soft magnetic material such as NiFe, 4 is Al ₂ O ₃ , SiO
Lower reproduction gap composed of insulating layer such as ₂
An amorphous alloy film for applying a lateral bias magnetic field to the R effect film, a lateral bias layer formed of a NiFe-based alloy, or the like,
6 is a non-magnetic layer made of Ta, Ti, SiO ₂ or the like, which magnetically separates the lateral bias layer 5 from the MR effect layer described later, 7 is an MR effect layer made of a NiFe-based alloy film or a NiCo-based alloy film, 8 Is a hard magnetic layer having a multilayer structure in which a non-magnetic film and a ferromagnetic film for controlling the magnetic domains of the MR effect layer 7 are alternately laminated, 9 is a lead layer formed of Au, W or the like, and 10 is Al.
_An upper reproducing gap made of an insulating layer such as ₂ O ₃ or SiO ₂ ,
11 is an upper shield layer made of NiFe or the like, 12 is Al
An insulating layer made of ₂ O ₃ , SiO _2, etc. for separating the MR effect head, which is a reproducing head, from the recording head, and 13 is N
a lower core of a recording head made of a soft magnetic film such as an iFe film,
Reference numeral 14 is a recording gap made of an insulating layer such as Al ₂ O ₃ or SiO ₂ , 15 is an upper core of a recording head made of a soft magnetic film such as NiFe, and 16 is a protective layer such as Al ₂ O ₃ .

In FIG. 2, 8a is a Cr film and 8b is Co.
It is a CrPt film, and a Cr film 8a, Co is formed on the MR effect layer 7.
The CrPt film 8b has a multilayer structure in which three nonmagnetic films and three ferromagnetic films are alternately laminated in this order, and the film thickness of each layer is 100Å.

The operation of the MR effect type thin film magnetic head having the above structure will be described below. During the reproducing operation, a constant sense current is supplied to the MR effect layer 7 via the lead layer 9. Then, the magnetic flux of information recorded on the opposing magnetic recording medium is reproduced and output as a change in electric resistance by the sensing portion of the MR effect layer 7, and the reproducing operation is performed by detecting this. At this time, the hard magnetic layer 8 which is a longitudinal bias layer has a multilayer structure of three or more layers having a large coercive force in which nonmagnetic layers and ferromagnetic layers are alternately laminated, and stable magnetic domain control can be performed. it can.

(Experimental Example 1) In order to confirm that a high coercive force can be obtained by making the hard magnetic layer, which is a longitudinal bias layer, have a multi-layer structure in which nonmagnetic layers and ferromagnetic layers are alternately laminated, The coercive force was measured when the number of layers of the Cr film and the CoCrPt film which is a ferromagnetic film was made constant, and each film thickness was changed, and the result is shown in FIG. FIG. 3 is a diagram showing the relationship between the thickness of the Cr film and the coercive force. In FIG. 3, for example, when the total thickness of the Cr film and the CoCrPt film is 1500Å, the thickness of one layer of the Cr film is 200Å and the CoCrPt film thickness is 100Å.

(Comparative Example 1) As a comparative example, a hard magnetic layer having a two-layer structure of a CoCrPt film and a Cr film having a film thickness of 500 liters was used as C.
The coercive force was measured when the r film thickness was changed, and the results are shown in FIG.

As is clear from FIG. 3, the coercive force of both the two-layer film and the five-layer film increases as the film thickness of the Cr film increases, but the dependence of the Cr film on the five-layer film is smaller. It was found that the value of coercive force was also high.

As described above, according to this embodiment, the longitudinal bias layer on the MR effect layer has a 6-layer structure in which a Cr film which is a non-magnetic film and a CoCrPt film which is a ferromagnetic film are alternately laminated by three layers each. The hard magnetic layer can increase the coercive force and stably control the magnetic domains of the MR effect layer, and the product yield can be improved by 30% or more as compared with the conventional hard magnetic layer of the two-layer film. did it.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is an enlarged cross-sectional view of a main portion of a vertical bias layer of an MR effect thin film magnetic head according to a second embodiment of the present invention. The difference from the first embodiment is that the hard magnetic layers 8'which are longitudinal bias layers for controlling the magnetic domains of the MR effect layer 7 are alternately stacked in the order of CoCrPt film 8b and Cr film 8a from the side in contact with the MR effect layer 7. The point is that a hard magnetic layer having a six-layer structure is formed by laminating three layers each.

The operation of the MR effect type thin film magnetic head having the above structure will be described below. The operation at the time of reproduction is the same as that of the first embodiment, but by disposing the ferromagnetic film on the MR effect layer side 7, the ferromagnetic film of the first layer and the MR
Ferromagnetic coupling with the effect layer 7, and magnetostatic coupling with the ferromagnetic film of the third layer through the non-magnetic film of the second layer,
Due to the two effects of the ferromagnetic coupling and the magnetostatic coupling, the magnetic domain of the MR effect layer 7 can be controlled more stably. The following experiment was conducted in order to confirm the effect of this ferromagnetic coupling and magnetostatic coupling.

(Experimental Example 2) In this experimental example, a CoCrPt film having a film thickness of 100Å and a Cr film having a film thickness of 100Å are formed on a NiFe film.
The BH characteristics were measured by laminating a multilayer film in which five films were alternately formed, and the results are shown in FIG. Figure 5 (a)
FIG. 4 is a diagram showing BH characteristics of a 5-layer film of CoCrPt film and Cr film.

Comparative Example 2 As a comparative example, a film thickness of 500Å
CoCrPt single layer film, coercive force 0.3 Oe film thickness 50
NiFe-CoCrPt composite film in which a CoCrPt film having a film thickness of 500Å is laminated on a NiFe layer having a film thickness of 0Å, a coercive force of 0.3.
Oe film thickness of 500Å on NiFe layer with 100Å film thickness of C
The B-H characteristics were measured for each of the three-layered films in which the r film was laminated and a CoCrPt film having a film thickness of 500 Å was further laminated, and the results are shown in FIGS. FIG. 5B shows N
It is a figure which showed the BH characteristic of the iFe-CoCrPt composite film, FIG.5 (c) is the figure which showed the BH characteristic which mediated the Cr film to the CoCrPt composite film, and FIG.5 (d) is CoCr.
It is a figure showing the BH characteristic of a multilayer film of a Pt film and a Cr film. When the hard magnetic layer is a CoCrPt single layer film having a film thickness of 500 Å, the coercive force is 1500 Oe as shown in FIG. 5 (b).
On the other hand, coercive force of 0.3 Oe and film thickness of 500ÅN
In the case of a composite film in which a CoCrPt film with a film thickness of 500 Å is formed on the iFe film, the coercive force is 2 as shown in FIG. 5 (c).
The value is 00 Oe, which is much smaller than that of a single layer film. Also, B-H
Since the curve shows a smooth shape, it can be seen that ferromagnetic coupling occurs between the NiFe film and the CoCrPt film. When a 100 Å Cr film is interposed between the NiFe film and the CoCrPt film, the BH characteristic is the sum of the magnetization curves of the NiFe film and the CoCrPt film, as shown in FIG. 5D. Since it is represented, it can be seen that magnetostatic coupling occurs. Furthermore, when a CoCrPt film having a film thickness of 100 Å and a Cr film having a film thickness of 100 Å are alternately formed on the NiFe film to form a multilayer film, five layers each have BH characteristics as shown in FIG. C in direct contact with the membrane
It is expressed as the sum of the magnetization curves of the ferromagnetic coupling with the oCrPt film and the remaining CoCrPt films. That is, it is possible to cause both ferromagnetic coupling and magnetostatic coupling simultaneously by the pair of hard magnetic layers.

(Experimental Example 3) Ten MR effect type magnetic heads having the same structure as in Example 2 were prepared and a peripheral speed of 8 m / s and a recording frequency of 6 MH were used by using a 3.5-inch magnetic disk device.
The recording / reproducing characteristics were measured by z. The measurement method was to record and reproduce 6MHz signals 10 times in succession, and average (x)
Then, the variation (δ) was obtained, and δ / x was obtained as an index of the stability of recording and reproduction. Table 1 shows the average value and variation of δ / x for ten MR effect thin film magnetic heads.

[0023]

[Table 1]

(Comparative Example 3) As Comparative Example 3, ten MR effect thin film magnetic heads in which the hard magnetic layer of the longitudinal bias layer is a CoCrPt single layer film and are in direct contact with the MR effect layer are prepared.
A recording / reproducing characteristic test was conducted under the same conditions as in Experimental Example 3. The results are shown in (Table 1).

(Comparative Example 4) As Comparative Example 4, a hard magnetic layer having the same structure as in Example 2 was laminated with a Cr film on the MR effect layer,
Ten Co effect magnetic thin film magnetic heads were prepared by stacking a CoCrPt film on top of this and 10 recording and reproducing characteristics tests were conducted under the same conditions as in Experimental Example 2, and the results are shown in (Table 1).

As described above, according to this embodiment, the ferromagnetic film of the hard magnetic layer having a multilayer structure constituted by alternately stacking the ferromagnetic film and the non-magnetic film is directly laminated on the MR effect layer. By the two effects of ferromagnetic coupling and magnetostatic coupling
The magnetic domain of the effect layer can be controlled.

In this embodiment, Ni is used as the MR effect film.
Although the CoCrPt film is exemplified as the Fe film and the hard magnetic layer,
It is confirmed that the same effect can be obtained by using NiCo-based alloy film or amorphous alloy film as the soft magnetic film and CoNi film, CoCrTa film or the like as the hard magnetic layer without limiting the material in particular. . The non-magnetic film is not limited to the Cr film, but may be Ta, Ti, W or the like.
Further, although the number of layers is not particularly limited, in order to utilize both ferromagnetic coupling and magnetostatic coupling at the same time, the number of hard magnetic layers must be three or more with non-magnetism between the ferromagnetic layers. Is. Further, the ratio of the ferromagnetic coupling and the magnetostatic coupling can be arbitrarily selected by changing the film thickness of the hard magnetic layer per layer, so that it can be applied to each MR effect thin film magnetic head and the optimization can be easily performed. It is possible.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a sectional view of the essential parts of an MR effect type thin film magnetic head according to the third embodiment of the present invention. The difference from Example 1 is that the hard magnetic layer 8 is provided on the lead layer 9 side of the upper shield layer 11 to control the magnetic domains of both the MR effect layer 7 and the upper shield layer 11.

A recording / reproducing characteristic test was conducted on the MR effect type thin film magnetic head constructed as described above.

(Experimental Example 4) Ten MR effect thin film magnetic heads having the same construction as in Example 3 were prepared, and the recording / reproducing characteristics were measured under the same conditions as in Experimental Example 3. The results are shown in (Table 1).

As is clear from this (Table 1), by controlling the magnetic domains of both the shield layer and the MR effect layer,
It turns out that Barkhausen noise can be suppressed more.

As described above, according to the present embodiment, by controlling the magnetic domains of both the MR effect layer and the shield layer by the hard magnetic layer having the multilayer structure, the MR effect type having optimum characteristics without Barkhausen noise. A thin film magnetic head can be obtained.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a cross-sectional view of an essential part of an MR effect thin film magnetic head according to the fourth embodiment of the present invention. The difference from Example 1 is that the hard magnetic layer below the lead layer 9 is not arranged, but the hard magnetic layer 8 is provided on the lead layer 9 side of the upper shield layer 11 to control the magnetic domain of the upper shield layer 11. That is the point.

A recording / reproducing characteristic test was conducted on the MR effect type thin film magnetic head configured as described above.

(Experimental Example 5) Ten MR effect type thin film magnetic heads having the same construction as in Example 3 were prepared, a recording / reproducing characteristic test was conducted under the same conditions as in Experimental Example 1, and the results are shown in (Table 1). Indicated.

As is clear from (Table 1), it was found that Barkhausen noise can be suppressed by controlling the magnetic domain of the upper shield layer.

As described above, according to this embodiment, Barkhausen noise can be reduced by controlling the magnetic domain of the upper shield layer. Further, by providing the hard magnetic layer under the upper shield layer, the underlayer for increasing the coercive force of the hard magnetic layer can be made thicker in the process, so that a single layer film is also effective. In this case, it is more effective not to ferromagnetically couple the upper shield layer and the hard magnetic layer via a non-magnetic film such as a Cr layer.

[0038]

As described above, according to the present invention, the coercive force is enhanced by the hard magnetic layer having a multilayer structure of three or more layers in which the ferromagnetic film and the non-magnetic film are alternately laminated, and the bias magnetic field is permanently applied. The magnetic field can be supplied and the magnetic domain can be stably controlled. Also, since ferromagnetic coupling and magnetostatic coupling can be used simultaneously, M
The magnetic domain of the R effect layer and / or the upper shield layer can be more effectively controlled, the Barkhausen noise can be reduced, and the MR effect type thin film magnetic head having high performance and excellent reliability can be realized. .

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an MR effect thin film magnetic head in a first embodiment of the invention.

FIG. 2 is an enlarged view of part A of FIG.

FIG. 3 is a diagram showing the relationship between the thickness of the Cr film and the coercive force.

FIG. 4 is an enlarged cross-sectional view of an essential part of a vertical bias layer of an MR effect thin film magnetic head according to a second embodiment of the present invention.

FIG. 5 (a) B- of a five-layer film of CoCrPt film and Cr film.
Figure showing H characteristics (b) Figure showing BH characteristics of NiFe-CoCrPt composite film (c) Figure showing BH characteristics of CoCrPt composite film with Cr film interposed (d) CoCrPt film and Cr The figure which showed BH characteristic of the multilayer film of a film

FIG. 6 is a sectional view of an essential part of an MR effect thin film magnetic head in a third embodiment of the invention.

FIG. 7 is a cross-sectional view of an essential part of an MR effect thin film magnetic head according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Substrate 2, 12 Insulating Layer 3 Lower Shield Layer 4 Lower Reproducing Gap 5 Transverse Bias Layer 6 Non-Magnetic Layer 7 MR Effect Layer 8, 8'Hard Magnetic Layer 8a Cr Film 8b CoCrPt Film 9 Lead Layer 10 Upper Reproducing Gap 11 Upper Shield Layer 13 Lower core 14 Recording gap 15 Upper core 16 Protective layer

Claims (4)

[Claims] 1. A magnetoresistive effect thin film magnetic head comprising a reproducing sensing part having a lateral bias layer, a magnetoresistive effect layer, a hard magnetic layer, a lead layer, etc. between a lower shield layer and an upper shield layer. A magnetoresistive effect thin film magnetic head, wherein the hard magnetic layer has a multilayer structure of three or more layers in which ferromagnetic films and nonmagnetic films are alternately laminated. 2. The magnetic according to claim 1, wherein the hard magnetic layer is formed in direct contact with the lead layer side of the magnetoresistive effect layer and / or the lead layer side of the upper shield layer. Resistive thin film magnetic head. 3. The magnetoresistive effect layer of the hard magnetic layer and / or
The magnetoresistive thin-film magnetic head according to claim 2, wherein the layer in contact with the upper shield layer is a ferromagnetic film. 4. A magnetoresistive effect thin film magnetic head comprising a reproducing sensing part having a lateral bias layer, a magnetoresistive effect layer, a hard magnetic layer, a lead layer, etc. between a lower shield layer and an upper shield layer. The magnetoresistive effect thin film magnetic head, wherein the hard magnetic layer is a single hard magnetic layer and is formed on the lead layer side of the upper shield layer with a nonmagnetic film interposed therebetween.