JPS60224115A - Magnetoresistance effect type head - Google Patents

Abstract

PURPOSE:To decrease the difference in the characteristics of two magnetoresistance effect elements and to decrease the waveform distortion to be generated in a reproduction signal by constituting the two magnetoresistance effect elements provided via a non-magnetic insulating layer between a magnetic substrate and high permeability member to the relation in which the magnetostriction constant of one thereof is smaller than the magnetostriction constant of the other. CONSTITUTION:The two magnetoresistance effect (MR) elements of a magnetoresistance effect type magnetic head having the two MR element layers are so constituted as to decrease the difference in the MR characteristic indicating the relation between the resistivity of the MR element and magnetic field intensity for example, an Ni-Fe material having 81.0% nickel content at which the magnetostriction constant lambda1 attains lambda1=+0.6X10<-6> is used as the 1st MR element and an Ni-Fe material having 80.8% nickel content at which the magnetostriction constant lambda2 attains lambda2=+0.7X10<-6> is used as the 2nd MR element. The MR characteristics of both elements are provided by making equal the magnetic elastic energy, by which the distortion of the reproduction signal is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (81) Technical Field of the Invention The present invention relates to an improvement in a magnetoresistive magnetic head used as a reproducing head in a magnetic disk device, a magnetic tape device, or the like.

(bl) Prior Art and Problems FIG. 1 shows a sectional view of essential parts of a conventional magnetoresistive magnetic head.

In this figure, 1 is N1-Zn (ferrite), Mn
-Magnetic substrates made of Zn (ferrite), etc., 2 and 2"
is N1-Be (permalloy), 'a magnetoresistive element (hereinafter abbreviated as MR element) made of a magnetic thin film such as Ni-Co, and 3.3', 3'' and 5 are non-magnetic insulators such as 5t-OH. The layer 4 is a high magnetic permeability material such as N1-Fe (permalloy), 6 is a cover glass, and 7 is a magnetic tape that moves in contact with a magnetoresistive magnetic head (hereinafter abbreviated as MR head).

The magnetic substrate 1 and the high magnetic permeability member 4 are formed so as to sandwich an MR element 2.2' surrounded by a non-magnetic insulating layer therebetween, 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, and shows the state in which the resistivity ρ changes in response to the external magnetic field that the MR element receives. Generally, in an MR head, means for applying a bias magnetic field Hb is used in order to use this linear region of MR characteristics.

FIG. 3 shows a diagram for explaining the operating principle of two MR elements. In the figure, a bias magnetic field Hbl, H>2 is mutually applied to the magnetic daso by supplying currents i of equal magnitude in the same direction to two MR elements 2 and 2'. Also, reproduced signals from the two MR elements 2 and 2' are detected by a differential amplifier 8.

Generally, in an MR head that reproduces digital signals,
The MR characteristics and the quality of the reproduced signal are closely related, and in the MR head with 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'.

Possible factors that affect the MR characteristics include the stress applied to the MR element in addition to the film formation method and film formation conditions of the MR element. The factors that cause stress will be explained below with reference to FIG.

a non-magnetic insulating layer 3' formed on the MR elements 2 and 2'';
3” and 5 are formed by sputtering method.
A t-0□ film was used, and the film thickness was 0.5°0.
5 and about 1.0-. When a 5i-0□ film is formed on a substrate using the sputtering method using the required argon gas pressure, high-frequency power, and maintaining the substrate at a predetermined temperature, the 5i-0□ film surface of the substrate is convex. From this, it can be seen that the residual stress of the 5t-0□ film is compressive stress, and that tensile stress acts on the substrate surface.

The high magnetic permeability member 4, which acts as a shielding magnetic material, is also formed of an N1-Fe (permalloy) film with a thickness of approximately 2 mm by sputtering. The residual stress of the high magnetic permeability member 4 thin film sputtered under the required film forming conditions is a compressive stress similar to the 5t-0□ film described above.

Therefore, the first MR element 2 has a non-magnetic insulating layer 3'.

The second MR element 2' receives stress from the nonmagnetic insulating layers 3'', 5 and the high magnetic permeability member 4. According to this stress receiving form, M
The difference between R elements 2 and 2'' is the stress of the non-magnetic insulating layer 3°.This causes a difference in MR characteristics, which has the drawback of causing distortion in the output reproduced signal.

ic) Purpose of the Invention In view of the above-mentioned conventional drawbacks, the present invention provides an MR system for two MR elements.
It is an object of the present invention to provide an MR head that reduces the difference in characteristics and causes less waveform distortion in reproduced signals.

According to the present invention, a first magnetoresistive element and a second magnetoresistive element are sandwiched between a nonmagnetic layer on a substrate made of a magnetic material.
In the magnetoresistive head, the magnetoresistive element is provided with magnetoresistive elements, and these re-magnetoresistive elements are sandwiched between magnetic materials having high magnetic permeability. This is achieved by providing a magnetoresistive head characterized in that the magnetoresistive constant is smaller than the magnetostriction constant of the magnetoresistive element.

(81 Examples of inventions Embodiments of the present invention will be described in detail below with reference to the drawings.

In both figures, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

Figure 4 is a graph showing the relationship between the film thickness and the amount of warpage of the substrate due to the Si-〇□ film and Ni-Fe film deposited by the sputtering method. 5i-(h film is shown. This amount of warpage is calculated using a standard rectangular crystal substrate (for example, length 32 m, width 211 m).

When a film is formed to a thickness of 0.4 m), the amount of warpage δ corresponding to the change in film thickness is measured in units of length.

The amount of warpage δ is a value proportional to the compressive stress σ.

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

On the other hand, MR elements 2 and 2' have a predetermined film thickness and substrate temperature.

It is formed by vapor deposition method under conditions such as vapor deposition rate, and -
Deposition is performed in a magnetic field to impart axial anisotropy.

Now, assuming that the magnetostriction constants of the Ni-Fe films forming MR elements 2 and 2'' are λl and A2, respectively, and the applied stresses are σl and 62, respectively, then the MR elements 2 and 2'' have -3λ1σl/2. -3 has a different magnetoelastic energy of 屹/2.

Furthermore, from the characteristics shown in FIG. 4, the amount of warpage of the first MR element 2 is larger than the amount of warpage of the second MR element 2'', so the compressive stress applied to the pixel element is proportional to σ1> It becomes a phrase.

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

This graph is for the case where all the magnetostriction constants are positive values,
When σ1>7F2, the rise of the phrase characteristic curve becomes steeper.

Therefore, in order to equalize the MR characteristics of both the first MR element 2 and the second MR element 2', it is sufficient to make the magnetoelastic energy equal to each other. In this case, since the thickness of the Si-0□ film deposited by sputtering, that is, the nonmagnetic insulating layers 3'', 3'', 5 and the high magnetic permeability member 4, cannot be changed, the magnetostriction constant λ1.A2 can be selected. Moreover, since it is a σ1〉 phrase, it becomes λ1〈. Fig. 6 is a graph showing the relationship between the Ni-Fe composition and the magnetostriction constant according to the embodiment of the present invention, and in view of the data in Fig. 4. , σl#, so a Ni-Fe composition (nickel content in permalloy) with a relationship of 1.2λ1 is applied. For example, for the first MR element, λ1 = +0.6 1
A Ni-Fe material with a nickel content of 81.0%, which is 0-6, is used as the second MR element.
' A Ni-Fe material with a nickel content of 80.8% is used.

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

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a conventional magnetoresistive magnetic head, Figure 2 is a characteristic curve diagram showing the relationship between the resistivity of the MR element and the strength of the magnetic field, and Figure 3 is the operation of the two MR elements. A diagram for explaining the principle. Figure 4 is a graph showing the relationship between the film thickness of the Si-0□ film and the Ni-Fe film deposited by sputtering and the amount of warpage of the substrate. Figure 5 is a graph showing the stress and MR characteristics. FIG. 6 is a graph showing the relationship between Ni-
A graph showing the relationship between Fe composition and 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 nonmagnetic thin films,
4 is a thin film of a high magnetic permeability member, λ1 is a magnetostriction constant of the first MR element, and λ1 is a magnetostriction constant of the second MR element. Figure 1 Figure 2 Figure 4 Obo (μm)

Claims (1)

[Claims] A first magnetoresistive element and a second magnetoresistive element are provided on a substrate made of a magnetic material with a nonmagnetic layer sandwiched therebetween, and both magnetoresistive elements are sandwiched between magnetic materials having high magnetic permeability. 1. A magnetoresistive head, characterized in that the magnetoresistive constant of the first magnetoresistive element is smaller than the magnetostriction constant of the second magnetoresistive element.