JPS63181109A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To reduce the Barkhausen noise by forming a rear electrode layer extremely widely from the front ridge of a coated part of a magnetic sensing part to the rear end toward the rear part. CONSTITUTION:In adopting the MR magnetic head (magneto-resistance effect type magnetic head) of shield type, the rear electrode layer 7 is widened rapidly toward the rear part especially and the improvement of Barkhausen noise is attained effectively by reducing the current density. Moreover, the magnetic sensing part 2 is prolonged in a direction being nearly orthogonal to the opposed contact face 3 of the magnetic recording medium, electrode layers 6, 7 are arranged at both ends and a signal magnetic field is given in a direction coincident with the direction of the sense current conducting direction, and in a direction orthogonal to the contact face 3 and the magnetic sensing part is adopted for the multi-layered structure of the magnetic sensing part 2, then the production of Barkhausen noise is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive magnetic head, particularly a shield type magnetoresistive magnetic head.

[Summary of the invention]

The present invention provides a pair of soft magnetic Fit! on a substrate, at least one of which has a magnetoresistive effect. ! are laminated with a non-magnetic intermediate layer interposed therebetween, with the front end face thereof facing the surface facing the magnetic recording medium, and extending backward from this in a direction substantially perpendicular to the surface facing the magnetic recording medium. A conductor for generating a bias magnetic field is arranged so as to extend, and a front electrode layer and a rear electrode layer are respectively deposited on the front end and the rear end of the magnetically sensitive part, and extend in a direction intersecting the extension direction of the magnetically sensitive part. A shield type structure is adopted in which a magnetic material is placed so as to cover the magnetic sensing part having the front and rear electrode layers and the area where the bias magnetic field generating conductor is arranged, and in particular, the rear electrode layer is placed on the magnetic sensing part. The width of the connecting portion is suddenly widened toward the rear from the front edge of the connecting portion to the rear end of the connecting portion, thereby effectively avoiding the occurrence of Barkhausen noise.

[Conventional technology]

Conventionally, a general magnetoresistive magnetic head (hereinafter referred to as an MR type magnetic head) has a magnetic sensing portion composed of a single-layer magnetic thin film having a magnetoresistive effect (hereinafter referred to as an MR magnetic thin film). When a shield type configuration is adopted, the magnetically sensitive part is arranged and formed on the substrate so that one end face faces the surface in contact with the magnetic recording medium, and a predetermined bias magnetic field is applied to this magnetically sensitive part. A conductor for generating a bias magnetic field is provided to generate a bias magnetic field, and a magnetic material for shielding is disposed so as to cover the magnetic sensing part and the area where the conductor for generating a bias magnetic field is arranged.

[Problem that the invention seeks to solve]

Does it have a magnetically sensitive part made of the above-mentioned single-layer MR magnetic thin film?
In IR type magnetic heads, Barkhausen noise,
In other words, noise generation due to movement of domain walls becomes a problem.

As an MR type magnetic head designed to avoid such Barkhausen noise, the present applicant previously filed a patent application in 1983.
- In the application No. 179135, Barkhausen noise is reduced by making the magnetic sensing part have a multilayer structure in which a pair of magnetic thin films are laminated with a non-magnetic intermediate layer interposed therebetween.
Furthermore, in Japanese Patent Application No. 60-247752, an MR type magnetic head was proposed in which the Barkhausen noise was further reduced by making the sense current flowing through the magnetic sensing part in the same direction as the signal magnetic field.

In this way, a pair of magnetic thin films as a magnetically sensitive part may be laminated with a non-magnetic intermediate layer interposed therebetween, or a change in resistance based on a signal magnetic field from a magnetic recording medium applied to this magnetically sensitive part may be expressed as a voltage change, for example. When selecting the sense current that flows in the same direction as the signal magnetic field, it is possible to reduce Barkhausen noise as will be explained later. In this case, there is Barkhausen noise due to the magnetization of the end of the magnetically sensitive part due to the magnetic field generated by the sense current flowing through this electrode layer in the electrode layer attachment part of the sense current supply to the magnetically sensitive part, and furthermore, Barkhausen noise is caused by the magnetization of the end of the magnetically sensitive part due to the magnetic field generated by the sense current flowing through this electrode layer. The problem of Barkhausen noise arises due to the effect on the magnetically sensitive part due to the magnetization of the provided shielding magnetic material.

The present invention attempts to solve these problems as well.

[Means for solving problems]

The present invention is shown in FIG.
As shown in the cross-sectional view on A-All in FIG. facing the contact surface (3) and extending rearward so as to be substantially orthogonal to this contact surface (3), and an m-edge gap (4) extending substantially orthogonally and across this magnetically sensitive portion (2). A conductor (5) for generating a bias magnetic field is formed to apply a bias magnetic field to the magnetically sensitive portion (2) through the magnetic field.

On the other hand, a front electrode layer (6) and a rear electrode layer are electrically connected to the front end and the rear end of the magnetically sensitive part (2), respectively, and serve to apply a sense current i to the magnetically sensitive part (2). (7)
Form the adhesion.

A magnetic field for shielding is formed by covering the area where the magnetic sensitive part (2) having the front electrode layer (6) and the rear electrode layer (7) and the bias magnetic field generating conductor (5) are arranged and passing it through the insulating layer (4). body(
8).

Although not shown, the magnetic recording medium is configured to move relatively in front of the facing surface (3) in a direction perpendicular to the main surface in FIG. 1.

As shown in FIG. 3, the magnetically sensitive part (2) is formed by laminating a pair of first and second soft magnetic thin films (9) and a frame with a nonmagnetic intermediate layer Oυ interposed therebetween. First and second soft magnetic thin films (9) and Q
At least one of them is formed by a soft magnetic thin film having an MR effect, for example, a thin film layer made of Fe+Go+Ni or an alloy of two or more of these such as NiFe, NiCo, NiFeCo, etc.

The non-magnetic intermediate NGO may be formed of an insulator such as SiO2, A1g02, or a non-magnetic metal layer such as Ti, Mo, Ag. This non-magnetic intermediate layer αυ is formed between the two soft magnetic m films (9) and 01 in such a way that the magnetostatic interaction acts more dominantly than the exchange interaction.
The thickness can be selected from 0 to 500 people, for example. Also,
MR of one of the first and second soft magnetic thin films (9) and αΦ
In the case of forming an ineffective soft magnetic thin film, the material may be a high magnetic permeability soft magnetic thin film such as sendust, Co-based amorphous alloy, Mo permalloy, or the like. In addition, both soft magnetic vyI films (
9) and α (to) are determined by selecting the saturation magnetic flux density, thickness, etc. so that the amount of magnetic flux of both the apical films (9) and 01 is the same, so that the magnetic flux is adjusted as a whole for both the apical films (9) and α (to). It will be closed automatically. And both magnetic thin films (9) and Q
When l is a magnetic thin film having an MR effect, it is desirable that both magnetic thin films (9) and OI be made of the same material and have the same size and shape.On the other hand, when they are made of a material that has no or almost no MR effect, It is desirable to select the specific resistance, thickness, etc. of the constituent materials of the soft magnetic thin film so that its electrical resistance is sufficiently greater than that of the soft magnetic thin film that has the MR effect.

In particular, in the present invention, in the above-mentioned configuration, the rear electrode layer (71) has a shape that rapidly widens rearward from the front edge (7a) of the part attached to the rear end of the magnetically sensitive part (21). be selected.

The front electrode layer (6) extends in the longitudinal direction of the bias magnetic field generating conductor (5).

In such a configuration, between the front electrode layer (6) and the rear electrode layer (7), that is, in the magnetically sensitive part (2), there is a direction perpendicular to the opposing surface (3), that is, the extension of the magnetically sensitive part (2). A sense current i is applied in the direction.

In addition, when the bias magnetic field generating conductor (5) is energized and no signal magnetic field is applied to the magnetically sensitive part (2), a required angle, for example approximately 45°, is set relative to the direction of the sense current i.
Apply a bias magnetic field that directs the magnetization.

Each of the soft magnetic thin films (9) and (to) of the magnetically sensitive part (2) has an axis of easy magnetization in a direction orthogonal to the direction of conduction of the sense current i, that is, in the width direction.

In the figure, t and t2 are both the front and rear electrode layers (6)
and shows the terminals derived from (7), T1 and T.

indicates terminals led out from both ends of the bias magnetic field generating conductor (5).

[For production]

According to the configuration of the present invention described above, Barkhausen noise is effectively removed. This will be explained.

First, to explain one of the causes of Barkhausen noise, it is common in the past. When the magnetic sensing part of the 1R type magnetic head is composed of a single-layer MR magnetic thin film as described above, this MR magnetic thin film has a magnetic anisotropy due to magnetic anisotropy energy, shape anisotropy, etc. The first
It has a magnetic domain structure as shown in Figure 0. In other words, this single N
When the Mi thin film is a rectangular magnetic thin film (51) and has magnetic anisotropy in the short side direction, magnetic domains (52) whose magnetization directions are alternately opposite are generated along the short side direction within the plane. At the same time, a magnetic thin film (51) is placed between both ends of these adjacent magnetic domains (52) to form a closed loop.
A magnetic domain (53) in the opposite direction is generated along the long side direction of ll. Therefore, when an external magnetic field is applied to such a magnetic thin film, the domain walls (54) and (55) move,
This causes Barkhausen noise.

In contrast, in the configuration of the present invention, the magnetically sensitive portion (2)
is layered with soft magnetic @@(9) and α[ through the non-magnetic intermediate NOυ, so that when no external magnetic field is applied, the soft magnetic thin film (9 ) and aI are in a magnetization state antiparallel to each other in the direction of the easy axis of magnetization, as shown by arrows M1 and M2, and no domain wall is formed.This absence of a domain wall can be explained by -(Bitt
Vf1 was confirmed by magnetic domain observation using the er) method.

When the external magnetic field H is strengthened in the direction of the hard magnetization axis for such a magnetically sensitive part (2), the magnetization state is shown in FIGS. 5A to 5C as shown by solid arrows for the soft magnetic thin film αl. , the soft magnetic thin film (9) is changed from the antiparallel magnetization state shown in FIG. 5A shown in FIG. 3 to the state shown in FIG. The magnetization is rotated by the rotational magnetization process, and both magnetic thin films (9) and α are magnetized in the same direction by a stronger external magnetic field, as shown in FIG. 5C. In this case, in both the soft magnetic thin films (9) and [alpha], the magnetization rotates within their planes, so no domain wall is generated, and Barkhausen noise is avoided. In other words,
Barkhausen noise caused by domain wall movement is avoided by setting the direction of the hard magnetization axes of both the soft magnetic thin films (9) and Ol as the propagation direction of the magnetic flux. Furthermore, the operation of the magnetic head having such a magnetic sensing portion (2) will be explained with reference to FIGS. 6 to 8. Figures 6 to 8 schematically show only the soft magnetic thin films (9) and 0 of the magnetically sensitive part (2). ni e, a
It has an axis of easy magnetization in the initial state in the direction shown by . That is, terminal 1. When a sense current i is passed between and tt,
It has easy axes of magnetization e and a in the direction orthogonal thereto. By applying a sense current i to these soft magnetic thin films (9) and (a), a current orthogonal to the current i is applied to both soft magnetic thin films (9) and O1 facing each other with a non-magnetic intermediate layer (not shown) in between. Magnetic fields in opposite directions are generated, and thereby the soft magnetic thin film (9) and Ql are magnetized as shown by solid and broken line arrows M and M2 in the figure. On the other hand, this magnetic sensing part (2
) is given an external bias magnetic field H in the direction along the current i as shown in FIG.
By a, the magnetization directions of the soft magnetic thin films (9) and 0 are rotated by a required angle, as shown by arrows M□ and MH in FIG. The magnitude of the bias magnetic field Hs is selected so that the direction of magnetization given by the bias magnetic field H1 is approximately 45° with respect to the direction of the current i. This bias magnetic field H6 is obtained by a bias magnetic field generating conductor (5) shown in FIGS. 1 and 2. The bias magnetic field H provides a magnetization of approximately 45' to the sense current i in order to operate in a region where the magnetic field-resistance characteristic curve shows high sensitivity and linearity. This is similar to what is done in a normal MR type magnetic head. In this state, as shown in FIG. 8, when a signal magnetic field Hs is applied in the direction along the sense current i, that is, in the direction of the hard magnetization axis, the magnetization rotates, and the direction of the magnetization is reversed as shown by the arrows MsI and Ml. Angle θ1 and -01 clockwise and clockwise
Rotate. As a result, if each soft magnetic thin film (9) and αφ are both MR magnetic thin films, a change in resistance will occur, but the change in resistance of this MR magnetic thin film is CO1 when the change in angle is θ. ! ``Since it is proportional to θ, both soft magnetic thin films (9) and α [
If the magnetizations Mll and MH of
An increase or decrease in resistance changes with respect to l.

In other words, if the resistance of one soft magnetic thin film (9) increases, the resistance of the other soft magnetic thin film also changes in the direction of increasing. Then, the resistance changes between these soft magnetic thin films (9) and the terminals 1 at both ends of the magnetically sensitive part (2). A resistance change occurs between terminals 1 and 11, and this resistance change can be detected as a voltage change between terminals 1° and t8.

In the configuration of the present invention, the contact surface (3) with the magnetic recording medium
The magnetic sensing part (2) is made to extend in a direction substantially perpendicular to , and a sense current i is passed in this extending direction, and as described above, the magnetic recording medium is The signal magnetic field Hs based on the recording magnetic field is applied, but the operational feature of such a configuration is that the direction of the sense current i is selected to be orthogonal to the direction of the signal magnetic field H8. It becomes clearer by comparison. That is, as shown in FIG. 11, in the same way as explained in FIG. In this state, the magnetic field generated by this magnetizes both the soft magnetic thin films (9) and α in the direction orthogonal to the current i, as shown by the solid and broken arrows, respectively. signal magnetic field H in the direction of
When s is given, this direction follows the magnetization of the soft magnetic thin film (9) and Ol due to the current i, and exhibits the same behavior as if this magnetic field Hs was given in the direction of the easy axis of magnetization. In other words, domain walls are generated and moved, resulting in Barkhausen noise.

If we consider a configuration in which a sense current i is passed in the direction of the easy axis of magnetization of the magnetic thin film and a signal magnetic field Hs is applied in the same direction as the sense current i, if the sense current i is relatively small, the magnetization of the magnetic layer The magnetization will be oriented in the easy axis direction, and the signal magnetic field Hs will be applied in the easy axis direction as shown in FIG. 11, which is undesirable as Barkhausen noise will occur. In other words, as in the present invention, the magnetically sensitive part (2) extends in a direction substantially perpendicular to the surface (3) facing the magnetic recording medium, and the electrode layer (6) is provided at the front and rear ends thereof.
) and (7) are provided so that the sense current i is passed in the direction orthogonal to the contact surface +3+ according to the extending direction of the magnetically sensitive part (2), in other words, in the same direction as the signal magnetic field from the magnetic medium. When doing so, the Barkhausen noise can be further improved.

In the above example, a magnetic thin film having an axis of easy magnetization in a direction substantially perpendicular to the signal magnetic field H5 was described, but it is also possible to use an isotropic magnetic layer having no magnetic anisotropy within the main surface of the magnetic thin film. The same applies. In this case, if a relatively small sense current is passed, the magnetization direction is perpendicular to the sense current, that is, perpendicular to the direction of the signal magnetic field, so Barkhausen noise does not occur.

Further, in the present invention, the rear electrode layer (7) for the rear end of the magnetically sensitive part (2) is connected from the front edge (7a) of the attached part to the rear end of the magnetically sensitive part (2). The Barkhausen noise can be improved by adopting a shape that widens steeply toward the rear. To explain this,
In the above configuration, the front electrode layer (6) is arranged so as to face the opposing surface (3) of the magnetically sensitive part (2), so that the magnetic field generated on the opposing surface (3) is biased. It is selected in the same direction as the magnetic field, but -a
As for the rear electrode layer (7), due to issues such as how to lead out the terminal from the bias magnetic field generating conductor (5), the sense current i in the direction of extension of the bias conductor, that is, in the magnetic sensing part (2)
Extending in the direction perpendicular to the
As shown in the figure, for the rear electrode layer (7), the magnetically sensitive part (2
), and the magnetic field generated in this electrode layer (7) is fixed in a direction different from the magnetization given by the bias magnetic field to the rear end of the magnetically sensitive part (2). , which causes a magnetic domain wall and causes Barkhausen noise.

Furthermore, when the magnetic material (8) for shielding is placed close to each other as in the case of a shield type configuration, this magnetic material (8) is magnetized by the magnetic field generated by the electrode layer (7), and this becomes sensitive. This affects the magnetic part (2) and causes Barkhausen noise. However, according to the present invention, the width of the electrode N (7) is suddenly widened from the attachment part at the rear end of the magnetically sensitive part (2), so that the current path there can be dispersed, and the current density can be sufficiently reduced. Therefore, the effect of the magnetic field generated thereby on the magnetic sensing part (2) and further on the magnetic body (8) can be reduced, and Barkhausen noise can be reduced. .

〔Example〕

With reference to FIGS. 1 and 2, the shield type M according to the present invention
An example of the R magnetic head will be described in detail. In this case the substrate (
11 is, for example, Nt-Zn ferrite, Mn-Z'n
The insulating layer (4) of 5iot or the like is deposited on this if necessary, and a soft magnetic thin film having at least one-sided force <l' IR effect is formed on this. (9) and Ql are laminated via a non-magnetic intermediate layer αD. It is formed to extend in a band shape in a direction perpendicular to the facing surface (3).

Then, a front electrode layer (6) and a rear electrode layer (7) having good electrical conductivity and having non-magnetism or soft magnetism are respectively deposited on the front end and the rear end of the magnetically sensitive part (2).

As mentioned above, the front electrode layer (6) has its end face facing the opposing surface (3) and extends along this, and the rear electrode layer (7) extends along the magnetically sensitive part (2). For example, a trapezoidal pattern is formed that rapidly spreads backward from the front edge (7a) of the part to be attached to the rear end.Furthermore, the electrode layers (6) and (7) and the magnetically sensitive part (2) are A conductor (5) for generating a bias magnetic field crosses over the magnetically sensitive part (2) in a direction perpendicular to the extending direction of the magnetically sensitive part (2) via the insulating layer (2).
A magnetic material (8) for shielding is further deposited on this with an insulating layer (1) interposed therebetween.

(2) and α ship are the front electrode N (6) and the rear electrode layer (7
), and (15a) and (15b) indicate terminal lead-out parts led out from both ends of the bias magnetic field generating conductor (5).

In addition, the soft magnetic thin film (9) constituting each of these magnetically sensitive parts (2)
.

The intermediate layer αD1 electrode layer T6), +71, and the bias magnetic field generating conductor (5) can be formed by, for example, full-surface evaporation sputtering, and then patterned by photolithography.

In addition, in the example shown in FIG. 1, one magnetic sensing section (2) is arranged within one track width, but as shown in FIG. It is also possible to adopt a configuration in which a plurality of, for example, two magnetically sensitive parts (2) are arranged in parallel, and in this case also, the rear electrode layer (7)
is the front edge (7a) of the attached part with the rear end of the magnetically sensitive part (2)
It can be formed into a shape that sharply diverges from each other in other directions.

〔Effect of the invention〕

As described above, according to the present invention, when a shielded MR magnetic head is configured, the rear electrode layer (7) in particular is made wide so as to steeply spread rearward, thereby reducing the current density that leads to the rear electrode layer (7). This effectively improves Barkhausen noise. In addition, the magnetic sensing part (2)
extends in a direction substantially perpendicular to the surface (3) in contact with the magnetic recording medium, and electrode layers (6) and (7) are arranged at both ends thereof to direct the sense current orthogonally to the surface (3) in contact with the magnetic recording medium. The generation of Barkhausen noise is effectively suppressed by applying the signal magnetic field in the same direction as the sense current direction, and by making the magnetic sensing part (2) a magnetic sensing part with a multilayer structure. This makes it possible to obtain a shielded MR type magnetic head that avoids this problem.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of an example of a magnetic head according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. A pattern diagram of the main parts of a magnetic head according to another example of the present invention, FIG. 5 is an explanatory diagram of the magnetization state of the magnetic sensitive part due to an external magnetic field, and FIGS. 6 to 8 are explanatory diagrams of the operation.
FIG. 9 is a diagram showing the magnetic sensing part and electrode arrangement of a comparative example, FIG. 10 is a diagram showing a single-layer magnetic thin film magnetic domain structure, and FIG. 11 is an explanatory diagram of the comparative example. (1) is the substrate, (2) is the magnetic sensing part, (3) is the surface in contact with the magnetic recording medium, (4) is the insulating layer, (5) is the bias magnetic field generating conductor, and (6) is the front electrode. layer, (7) is the rear electrode layer,
(9) and α· are soft magnetic thin films, and on is a nonmagnetic intermediate layer.

Claims (1)

[Scope of Claims] A magnetic sensing part provided on a substrate so as to extend rearward and substantially perpendicular to a surface in contact with a magnetic recording medium, with a front end face facing the contact opening, and the magnetic sensing part A conductor for generating a bias magnetic field is provided which extends across the magnetic field through an insulating layer, and a magnetic body is disposed to cover the magnetic sensing part and the area where the conductor for generating a bias magnetic field is arranged. The magnetically sensitive part is formed by laminating a pair of soft magnetic thin films, at least one of which has a magnetoresistive effect, with a nonmagnetic intermediate layer interposed therebetween, and a front electrode layer and a front electrode layer are provided at the front end and the rear end of the magnetically sensitive part, respectively. A rear electrode layer is deposited, the front end surface of the front electrode layer faces the surface that faces the magnetic recording medium, and the rear electrode layer extends rearward from the front edge of the connecting part to the rear end of the magnetically sensitive part. A magnetoresistive magnetic head is characterized by a sharply wider width.