JPH0624048B2 - Magnetoresistive head - Google Patents

Description

Description: (a) Technical Field of the Invention The present invention relates to an improvement of a magnetoresistive effect magnetic head used as a reproducing head of a magnetic disk device, a magnetic tape device or the like.

(b) Prior Art and Problems FIG. 1 is a sectional view of a main part of a conventional magnetoresistive head.

In this figure, 1 is a magnetic substrate made of Ni-Zn (ferrite), Mn-Zn (ferrite), etc., and 2 and 2'are Ni-Fe.
(Permalloy), a magnetoresistive effect element (hereinafter abbreviated as MR element) made of a magnetic thin film such as Ni-Co, 3, 3 ',
3 ″ and 5 are non-magnetic insulating layers such as Si—O ₂ , 4 are high magnetic permeability members such as Ni—Fe (permalloy), 6 is a cover glass, and 7 is a magnetoresistive effect magnetic head (hereinafter abbreviated as MR head). Do)
It is a magnetic tape that moves in contact with.

The magnetic substrate 1 and the high-permeability member 4 are formed so as to sandwich the MR elements 2 and 2'encapsulated in the non-magnetic insulating layer between them, and act as a shield magnetic body.

FIG. 2 is a characteristic curve diagram (hereinafter abbreviated as MR characteristic) showing the relationship between the resistivity of the MR element and the strength of the magnetic field. The vertical axis represents the resistivity ρ, and the horizontal axis represents the magnetic field strength H, showing the state in which the resistivity ρ changes in accordance with the external magnetic field received by the MR element. Generally, in the MR head, a means for applying the bias magnetic field Hb is used because the linear region of this MR characteristic is used.

FIG. 3 shows a diagram for explaining the operating principle of the two MR elements. In the figure, bias magnetic fields H _b1 and H _b2 are mutually applied to the magnetic tape by supplying a current i having the same magnitude in the same direction to the two MR elements 2 and 2 ′.
The reproduced signals from the two MR elements 2 and 2'are detected by the differential amplifier 8.

Generally, in an MR head that reproduces a digital signal,
The MR characteristic and the quality of the reproduced signal are closely related, and in the MR head having the two-layer MR element described above, the first M
It is necessary to match the MR characteristics of the R element 2 and the second MR element 2 '.

As the factors that affect the MR characteristics, the stress applied to the MR element may be considered in addition to the method of forming the MR element and the film forming conditions. The cause of stress will be described below with reference to FIG.

Second, third and fourth formed on the MR elements 2 and 2 '.
Si-O ₂ films formed by the sputtering method are used for the non-magnetic insulating layers 3 ′, 3 ″, and 5 of the above, and the film thicknesses are about 0.5, 0.5, and 1.0 μm, respectively. When a Si-O ₂ film is formed on the substrate while maintaining the gas pressure, the high frequency power and the substrate at a predetermined temperature, the substrate warps so that the Si-O ₂ film surface becomes convex. It can be seen that the residual stress of the O ₂ film is a compressive stress, and a tensile stress acts on the substrate surface.

The high magnetic permeability member 4 acting as a shield magnetic body is also formed of a Ni—Fe (permalloy) film having a film thickness of about 2 μm by the sputtering method. The residual stress of the thin film of the high magnetic permeability member 4 sputtered under the required film forming conditions is a compressive stress like the Si-O ₂ film.

Therefore, the first MR element 2 receives stress from the second, third and fourth non-magnetic insulating layers 3 ′, 3 ″, 5 and the high magnetic permeability member 4, and the second MR element 2 ′ receives the stress. It receives stress from the third and fourth non-magnetic insulating layers 3 ″ and 5 and the high magnetic permeability member 4. According to this stress receiving mode, the MR elements 2 and 2'are different from each other by the stress amount from the second nonmagnetic insulating layer 3 '. For this reason, there is a drawback that a difference occurs in the MR characteristics and the output reproduced signal is distorted.

(c) Object of the Invention In view of the above-mentioned conventional drawbacks, the present invention provides an MR of two MR elements.
It is an object of the present invention to provide an MR head in which the difference in characteristics is reduced and the reproduced signal has less waveform distortion.

(d) Structure of the Invention According to the present invention, there is provided a first magnetoresistive effect element, a second nonmagnetic insulating layer, a second nonmagnetic insulating layer, No. 2 magnetoresistive element is laminated, and a magnetic material having a high magnetic permeability is further laminated on the magnetoresistive element by means of a third nonmagnetic insulating layer, and the second and third nonmagnetic insulating layers are formed by a sputtering method. In the formed magnetoresistive head, the magnetostriction constant of the first magnetoresistive element on the substrate side is set to the second magnetic so that the magnetoelastic energies held by the magnetoresistive elements are substantially the same. This is achieved by providing a magnetoresistive head having a structure in which the magnetostriction constant of the resistance element is smaller than that of the magnetoresistive element.

(e) Embodiments of the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the corresponding parts to those in FIGS. 1 to 3 are designated by the same reference numerals, and the duplicate description thereof will be omitted.

Figure 4 shows Si-O ₂ film and N deposited by the sputtering method.
It is a graph showing the relationship between the film thickness of the i-Fe film and the amount of warpage of the substrate. The straight line (1) shows the Ni-Fe film and (2) shows the Si-O ₂ film.
The amount of warpage is measured by measuring the amount of warpage δ, which corresponds to the change in film thickness, when the film is formed on a reference strip-shaped quartz substrate (eg, length 32 mm, width 2 mm, thickness 0.4 mm). It was done. The amount of warpage δ is a value of a property proportional to the above-mentioned compressive stress σ.

FIG. 5 is a graph showing the relationship between stress and MR characteristics.

On the other hand, the MR elements 2 and 2'are formed by a vapor deposition method under the conditions of a predetermined film thickness, substrate temperature, vapor deposition rate, etc., and vapor deposition is performed in a magnetic field to impart uniaxial anisotropy.

Now, assuming that the magnetostriction constants of the Ni—Fe films forming the MR elements 2 and 2 ′ are λ ₁ and λ ₂ , respectively, and the applied stresses are σ ₁ and σ ₂ , respectively, the MR elements 2 and 2 ′ are −
3λ ₁ σ _1/2, will have a magnetoelastic energy different that -3λ ₂ σ _2/2.

Further, from the characteristics shown in FIG. 4, the warp amount of the first MR element 2 becomes larger than the warp amount of the second MR element 2 ', so that the compressive stress applied to both elements is proportional to σ ₁ > Σ ₂ .

FIG. 5 is a graph showing the relationship between stress and MR characteristics.
This graph shows the case where all magnetostriction constants are positive values,
When σ ₁ > σ _2, the rising of the characteristic curve of σ ₂ is steeper.

Therefore, in order to equalize the MR characteristics of both the first MR element 2 and the second MR element 2 ', the above-mentioned magnetoelastic energies may be made equal. In this case, since the film thickness of the Si—O ₂ film deposited by the sputtering method, that is, the second, third and fourth non-magnetic insulating layers 3 ′, 3 ″, 5 and the high magnetic permeability member 4 cannot be changed, The magnetostriction constants λ ₁ and λ ₂ may be selected, and since σ ₁ > σ ₂ , λ ₁ <λ ₂ .

FIG. 6 is a graph showing the relationship between the Ni—Fe composition and the magnetostriction constant according to the example of the present invention. In view of the data in FIG. 4, σ ₁ > σ ₂ , so 1.2λ ₁ ≈ The Ni-Fe composition (content of nickel contained in permalloy) having the relationship of λ ₂ is applied. For example, as the first MR element, λ
_1- + 0.6 × 10 ^-6 Ni-Fe material with a nickel content of 81.0% is used, and the second MR element is λ ₂ = + 0.7 × 10 ^-6 Ni-Fe with a nickel content of 80.8% Use material.

(f) Effects of the Invention As described in detail above, according to the magnetoresistive head of the present invention, since the MR characteristics of both the first MR element and the second MR element can be made uniform, reproduction This has the effect of reducing signal distortion.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a conventional magnetoresistive effect magnetic head, FIG. 2 is a characteristic curve diagram showing the relationship between the MR element resistivity and the magnetic field strength, and FIG. 3 is the operating principle of two MR elements. FIG. 4 is a diagram for explaining the above, and FIG. 4 was deposited by a sputtering method.
FIG. 5 is a graph showing the relationship between the film thickness of the Si—O ₂ film and the Ni—Fe film and the amount of warpage of the substrate, FIG. 5 is a graph showing the relationship between stress and MR characteristics, and FIG. -A graph showing the relationship between the Fe composition and the magnetostriction constant is shown. In the figure, 1 is a substrate, 2 is a first MR element, 2'is a second MR element, 3, 3 ', 3 "and 5 are first, second, third and fourth non-magnetic insulating thin films. 4 is a thin film of high magnetic permeability member,
λ ₁ is the magnetostriction constant of the first MR element, and λ ₂ is the magnetostriction constant of the second MR element.

Claims (1)

[Claims] 1. A first magnetoresistive element (2) and a second nonmagnetic insulating layer (3 ') on a substrate (1) made of a magnetic material with a first nonmagnetic insulating layer (3) interposed therebetween. , A second magnetoresistive effect element (2 ') is laminated, and a magnetic material (4) having a high magnetic permeability is further laminated on the second magnetoresistive effect element (2') via the third nonmagnetic insulating layer (3 "). In a magnetoresistive effect head in which the second and third non-magnetic insulating layers (3 ', 3 ") are formed by a sputtering method, the magnetoelastic energy held by each of the magnetoresistive elements (2, 2'). the magnetostriction constant of the substrate (1) side of the first magnetoresistive element (2) to substantially the same (lambda ₁₎ the second magnetoresistive element (2 ') magnetostriction constant of (lambda ₂₎ A magnetoresistive head having a smaller relationship.