JPS63184906A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To prevent Barkhausen noises from increasing owing to the narrowing of tracks by narrowing down only the front end surface of a magnetic sensing part formed by laminating a couple of soft magnetic thin film across a nonmagnetic intermediate layer or its periphery which faces the contacting surface for a magnetic recording medium to necessary narrow width, and increasing the width to the rear part. CONSTITUTION:The front end surface of the magnetism sensing part 2 which faces the contacting surface 3 for the magnetic recording medium or its peripheral part is narrowed down to the necessary narrow width, and the width is increased gradually to the rear part. Further, a conductor 5 for bias magnetic field production is arranged and formed across an insulating layer 4 so as to cross the magnetism sensing part 2 almost at right angles. Thus, the magnetism sensing part 2 is widened toward the rear part and extended crossing the contacting surface 3 for the magnetic recording medium almost at right angles, and electrode layers 6 and 7 are arranged at both ends of it; and the magnetism sensing part 2 is formed in multilayered structure to evade effectively the generation of Barkhausen noises.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetoresistive magnetic head.

[Summary of the invention]

The present invention provides a magnetosensitive section in which a pair of soft magnetic thin films, at least one of which has a magnetoresistive effect, is laminated on a substrate with a nonmagnetic intermediate layer interposed therebetween, the front end surface of which is in contact with a magnetic recording medium. The structure is such that the magnetic sensing part is arranged so as to extend in a direction substantially perpendicular to the contact surface, and only the front end face facing the contact surface with the magnetic recording medium or its vicinity is narrowed to the required narrow width. The trunk is widened toward the rear to avoid an increase in Barkhausen noise that would otherwise be caused by a narrower trunk.

[Conventional technology]

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

[Problem that the invention seeks to solve]

MR having a magnetically sensitive part made of the above-mentioned single-layer magnetic thin film
In the type magnetic head, there is a problem of Barkhausen noise, that is, noise caused by movement of domain walls.

The present applicant previously proposed a patent application filed in 1983-1 for an inter-type magnetic head designed to avoid such Barkhausen noise.
According to the patent application No. 179135, Barkhausen noise was reduced by providing a magnetic sensing part with a multilayer structure in which a pair of magnetic thin films were laminated with a non-magnetic intermediate layer interposed therebetween.
In the patent application No. 0-247752, an MR type magnetic head was proposed in which the Barkhausen noise was further reduced by making the sense current flowing through the magnetically sensitive part have the same direction as the signal magnetic field.

Such a magnetically sensitive part may have a structure in which a pair of magnetic thin films are laminated with a non-magnetic intermediate layer in between, or a resistance change based on the signal magnetic field from the magnetic recording medium applied to this magnetically sensitive part and the signal time. For example, if the sense current for detecting a voltage change is selected in almost the same direction, Barkhausen noise can be reduced, as will be explained later. Recently, in hard disk drives, etc., the trunk width has been further reduced, for example, to a width of 3 to 6 μm, which is less than 1 apm, and accordingly, the width of the magnetically sensitive part has been reduced to a width corresponding to the required trunk width. However, there is a problem in that Barkhausen noise is unavoidable even in a magnetically sensitive part having a multilayer structure. Figures 11 and 12 show the measurement results of the output (resistance change x current) when the width of the MR magnetic sensing part is 3 μm and 10 μm, respectively.As the width becomes narrower, significant hysteresis occurs. ing.

The present invention aims to effectively avoid the occurrence of Barkhausen noise due to the narrowing of the width of the magnetically sensitive portion accompanying the narrowing of the track width.

[Means for solving problems]

As shown in FIG. 1 is an enlarged plan view of the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG.
A magnetically sensitive part (2) having an MR effect (magnetoresistive effect) on the top, with its front end face facing the surface (3) in contact with the magnetic recording medium,
In addition, it extends rearward so as to be almost orthogonal to this contact surface (3), and furthermore, only the front end face facing the contact surface (3) or its vicinity is set to a required narrow width WS of, for example, 3 to 6 μm, and is further rearward from this. gradually or smoothly changing toward W
The width W is larger than s, for example, 10 μm or more.

In addition, a bias magnetic field generating conductor (5) for applying a bias magnetic field to the magnetically sensitive part (2) via the insulating layer (4) is provided so as to cross the magnetically sensitive part (2) almost perpendicularly. Form the arrangement.

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 applied over an insulating layer (4) over the magnetic sensing part (2) having the front electrode layer (6) and the rear electrode layer (7) and the arrangement part of the bias time generating conductor (5). 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 composed of a pair of first and second soft magnetic iJ films (9) and (10) and a non-magnetic intermediate layer (11).
). At least one of the first and second soft magnetic thin films (9) and (10) is a soft magnetic thin film having an MR effect, such as Fe, Co, Ni, or an alloy of two or more of these, NiFe, NiCo, N.
It is formed of a thin film made of iFeCo or the like.

The non-magnetic intermediate layer (11) is 5i02. It can be formed of an insulator such as 87!2 (h) or a nonmagnetic metal layer such as Tt, Mo, or heg.The nonmagnetic intermediate layer (11) is formed between the soft magnetic thin films (9) and (10). In this case, there are five people in whom magnetostatic interaction acts more dominantly than exchange interaction.
The thickness can be selected from 10,000 people, for example 5 to 500 people. In addition, the first and second soft magnetic thin films (9) and (10)
When one of the two is formed of a soft magnetic thin film having no MR effect, the material thereof may be a high magnetic permeability soft magnetic thin film such as sendust, CO-based amorphous alloy, Mo permalloy, or the like. In addition, the amount of magnetic flux of both magnetic thin films (9) and (10) of this magnetically sensitive part (2) is determined by selecting their saturation magnetic flux density, thickness, etc. Both thin films (9) and (10) are aligned so that the magnetic flux is
It is made to be closed as a whole.

When both magnetic thin films (9) and (10) are magnetic thin films that have an MR effect, it is desirable that both magnetic thin films (9) and (10) be made of the same material and have the same size and shape. On the other hand, when the soft magnetic thin film is made of a material that has no or almost no MR effect, the specific resistance and thickness of the constituent material should be adjusted so that the electrical resistance is sufficiently larger than that of the soft magnetic thin film that has the liver effect. It is desirable to select the following.

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 N (7), that is, the magnetically sensitive part (2), there is a direction perpendicular to the opposing surface (3), that is, the extending direction of the magnetically sensitive part (2+). Sense current i is applied to.

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 (10) 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 (1 and t2 are both the front and rear electrodes m f6
) and (7), and T1 and T2 indicate terminals led out from both ends of the bias magnetic field generating conductor (5).

[Effect]

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

To explain one of the causes of mass and Barkhausen noise, when the magnetic sensitive part is composed of the R layer MR magnetic thin film as mentioned above, as in the case of a conventional general 11R type magnetic head, this MR In order to maintain a state in which the sum of magnetostatic energy caused by magnetic anisotropy energy, shape anisotropy, etc. is minimized for the entire layer, the magnetic thin film is
It has a magnetic domain structure as shown in the figure. That is, when this single-layer magnetic thin film is a rectangular magnetic thin film (51) and has magnetic anisotropy in the short side direction, magnetic domains ( 52) are generated, and magnetic domains (53) in opposite directions are generated sequentially along the long side direction of the magnetic thin film (51) between both ends of the magnetic thin film (51) so as to form a closed loop regarding these adjacent magnetic domains (52). Therefore, when an external magnetic field is applied to such a magnetic magnetic film, the domain wall (54) will form.

(55) moves, which causes Barkhausen noise.

In contrast, in the configuration of the present invention, the magnetically sensitive portion (2)
Since it has a structure in which soft magnetic thin films (9) and (10) are laminated via a non-magnetic intermediate Ji (11), it becomes soft magnetic as shown in Fig. 3 when no external magnetic field is applied. The thin films (9) and (10) are in a magnetized state antiparallel to each other in the direction of the easy axis of magnetization, respectively, as shown by arrows M and M2, and no domain wall is formed. This lack of presence in the domain wall can be solved by using a bitter using magnetic fluid.
This was confirmed by magnetic domain observation using the (Bitter) 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 changed to the solid line for the soft magnetic thin film (10) as shown in Figures 5A to C. with an arrow
The soft magnetic thin film (9) is rotated from the antiparallel magnetization state shown in FIG. 5A shown in FIG. 3 as shown in FIG. The magnetization rotates due to the magnetization process, and both magnetic thin films (9) and (10) are magnetized in the same direction by a strong external magnetic field, as shown in FIG. 5C. In this case, both soft magnetic thin films (9) and (1
0), the magnetization rotates within that plane, so no domain wall is generated and Barkhausen noise is avoided. In other words, Barkhausen noise caused by domain wall movement is avoided by making the direction of the hard magnetization axes of both soft magnetic thin films (9) and (10) the propagation direction of 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 (10) of the magnetically sensitive part (2).
0) has an axis of easy magnetization in the directions shown by e and a in FIG. 6 in the initial state. That is, when the sense current i is passed between the terminals L1 and L2, the easy magnetization axes e and a are in the direction perpendicular to the sense current i. These soft magnetic thin films (9
) and (10), a sense current i is applied to the soft magnetic thin films (9) and (10) facing each other with a non-magnetic intermediate layer (not shown) in between, so that a sense current i is applied in opposite directions perpendicular to the current i. A magnetic field is generated, whereby the soft magnetic thin films (9) and (10) are magnetized as shown by solid and broken line arrows M1 and M2 in the figure. On the other hand, this magnetically sensitive part (2) has a current i
When a bias magnetic field Ha is applied from the outside in the direction along the direction shown in FIG. The image is rotated by the required angle as shown in . The magnitude of this bias magnetic field 1 (the bias magnetic field s is selected such that the direction of magnetization given by H is approximately 45° with respect to the direction of the current i. This bias magnetic field 1 - I B is obtained by the bias magnetic field generating conductor (5) shown in Figs. This is done to operate in a region where the resistance characteristic curve shows high sensitivity and linearity, and is similar to what is done in normal old magnetic heads.In this state, as shown in Figure 8, the reliability is When the magnetic field H3 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 directions of the respective magnetizations are indicated by the arrows Ms1 and M S
2, rotate counterclockwise and clockwise by angles θ1 and −0. As a result, if the soft magnetic thin films (9) and (10) are both MR magnetic thin films, a change in resistance will occur, but the change in resistance of this MR magnetic thin film is caused by the change in angle θ. When cos2
Since it is proportional to θ, both soft magnetic thin films (9
) and (10) magnetization M8□ and MB2 are 90° to each other
If there is a deviation, the changes in resistance of both soft magnetic thin films (9) and (10) coincide with changes in θ1 and -θ1. In other words, if the resistance of one soft magnetic thin film (9) increases, the resistance of the other soft magnetic thin film (10) also changes in the direction of increasing. Then, a resistance change occurs between these soft magnetic thin films (9) and (10), that is, a resistance change occurs between terminals L1 and 22 at both ends of the magnetically sensitive part (2), and this resistance change is treated as a voltage change between terminals t1 and L2. This means that it can be detected.

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 magnetization 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 IIS. It becomes clearer by comparing 3. That is, as shown in Figure 11, both soft magnetic thin legs (9) and (10
), considering the anisotropic magnetic field I (K) of the soft magnetic thin film,
When a large current is passed through, both soft magnetic thin films (9) and (10) are magnetized by the magnetic field generated thereby in a direction orthogonal to the current i, as shown by the solid line and the broken arrow, respectively. In this state, when a signal magnetic field HS is applied in a direction perpendicular to the current i, this soft magnetic thin film (9
) and (10) along the magnetization due to the current i,
The behavior is similar to that when this magnetic field Lj s is applied in the direction of the easy axis of magnetization. In other words, domain walls are generated and moved, resulting in Barkhausen noise. Here, a sense current i is passed along the axis of easy magnetization of the magnetic thin film 1ilQ, and a sense current 'tA
Considering a configuration in which a signal magnetic field (Is) is applied in the same direction as r, if the sense current i is relatively small, the magnetization will be oriented in the direction of the easy axis of magnetization of the magnetic layer, and the signal magnetic field ■-i
As shown in FIG. 11, s is given in the direction of the axis of easy magnetization, which is undesirable because Barkhausen noise occurs. In other words, as in the present invention, the magnetically sensitive 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), so that the sense current i is passed in a direction perpendicular to the opposing 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. In this case, the Barkhausen noise will be further improved.

In the above example, a magnetic thin film having an axis of easy magnetization in a direction substantially orthogonal to the signal magnetic field Hs was described, but an isotropic magnetic layer having no magnetic anisotropy within the main surface of the magnetic thin film may be used. The same applies if you use In this case, if a relatively small sense current is caused to flow, the magnetization direction is perpendicular to the sense current, that is, perpendicular to the direction of the input −° C. magnetic field, so Barkhausen noise does not occur.

Furthermore, in the present invention, the pattern shape of the magnetically sensitive part (2) is made narrow as required at the front end facing the surface (3) in contact with the magnetic medium, but the substantial operating part behind this is made narrow. Since the width is made wider in , the hysteresis and therefore the Barkhausen noise can be improved, as is clear from the comparison of FIGS. 11 and 12 described above.

〔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 may be composed of a magnetic substrate such as Ni-Zn ferrite or Mn-Zn ferrite, and if necessary, an insulating layer (4) such as Si02 is deposited on this. Small (soft magnetic groove IIN, one of which has an MR effect)
9) and (10) are laminated with a non-magnetic intermediate layer (11) in between. , and is formed in a pattern that extends in a direction perpendicular to this contact surface (3) and spreads backward.

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 described above, the front electrode layer (6) is extended so that its one side end surface, that is, the front end surface faces the contact surface (3).

Furthermore, these electrode layers (6) and (7) and the magnetically sensitive part (2)
A conductor (5) for generating a bias magnetic field is deposited on the magnetically sensitive part (2) across the magnetically sensitive part (2) in a direction orthogonal to the extending direction of the magnetically sensitive part (2) via an insulating layer (12), and further On top of this, a magnetic material (8) for shielding is applied via an insulator 1'5 (12).

(13) and (14) are terminal lead-out portions led out from the front electrode layer (6) and the rear electrode 11 (7), respectively;
a) and (15b) show terminal lead-out portions 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)
.

(10), intermediate layer (11), electrode rfi (61,
(71, bias magnetic field generating conductor (5), each can be formed by full-surface vapor deposition, sputtering, etc., and patterned by photolithography.

In addition, in the example shown in FIG. 1, the magnetic sensing part (2) is 1
However, as shown in Fig. 4, it is possible to arrange a plurality of magnetically sensitive g15 (2+) in parallel within a required trunk width Tw. In this case, each magnetically sensitive part (
2) has a shape that spreads toward the rear.

〔Effect of the invention〕

As described above, according to the present invention, when a shielded MR magnetic head is configured, the magnetic sensing portion (2
) is widened to the rear, effectively improving Barkhausen noise. In addition, the magnetically sensitive part (2) is extended in a direction substantially perpendicular to the surface (3) in contact with the magnetic recording medium, and electrode layers (6) and (7) are provided at both ends of the magnetically sensitive part (2).
to direct the sense current in the direction perpendicular to the opposing surface (3),
Therefore, the signal magnetic field is applied in the same direction as the sense current direction, and the magnetic sensing part (2)
By making the magnetic sensing part □ of a multilayer structure, it is possible to obtain a shielded MR type magnetic heald in which the generation of Barkhausen noise is effectively avoided.

[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 domain structure of a single-layer magnetic thin film, FIG. 10 is an explanatory diagram of a comparative example, and FIGS. 11 and 12 are output characteristic curve diagrams when the magnetically sensitive portion width is varied. (11 is the substrate, (2) is the magnetic sensing part, (3) is the surface facing the magnetic recording medium, (4) is the insulating layer, (5) is the bias magnetic field generating conductor, (6) is the front electrode layer , (7) is the rear electrode layer,
(9) and (10) are soft magnetic thin films, and (11) is a nonmagnetic intermediate layer.

Claims (1)

[Scope of Claims] On the substrate, the front end face faces the facing surface with the magnetic recording medium, the front end face extends rearward substantially orthogonally to the facing surface, and the front end face facing the said facing surface or its vicinity is disposed on the substrate. A magnetically sensitive part having a pattern shape with a required narrow width and widening toward the rear, and a conductor for generating a bias magnetic field extending across the magnetically sensitive part via an insulating layer are provided, and these magnetically sensitive parts and a magnetic material is arranged to cover the area where the conductor for generating the bias magnetic field is arranged, and the sensing part is formed by laminating a pair of soft magnetic thin films, at least one of which has a magnetoresistive effect, with a non-magnetic intermediate layer interposed therebetween. A magnetoresistive magnetic head characterized by: