JPS63244408A - Magnetoresistance type magnetic head - Google Patents

Abstract

PURPOSE:To improve the reproduced output characteristic by constituting a magnetic thin film by two layer of magnetic layers via a nonmagnetic intermediate layer and applying a current to one of the magnetic layers in a direction nearly orthogonal to the track width direction so as to improve the Barkhausen effect effectively. CONSTITUTION:The lamination structure where two magnetic layers 11, 12 are laminated via a nonmagnetic intermediate layer 10 are laminated is adopted for the magnetic thin film and a current (i) is applied at least to one of the two magnetic layers 11 and 12 in a direction nearly orthogonal to the track width direction in a magnetoresistance type magnetic head provided with an MR effect element 1 and the magnetic thin film leading signal magnetic flux to the MR effect element 1. The thickness (t) of the nonmagnetic intermediate layer 10 in the magnetic film is selected, for example, as 5<=t<=1,000Angstrom so that the Coulomb interaction is more dominant between both the magnetic layers 11 and 12 than the exchange interaction and the thickness is negligibly small as the magnetic gap. Thus, Barkhausen noise is sufficiently made small even in the narrow track width.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetoresistive magnetic head, particularly a magnetoresistive head having a magnetic thin film that guides signal magnetic flux from a magnetic recording medium to a magnetoresistive element thereof. Related to type magnetic heads.

[Summary of the invention]

The present invention provides a magnetoresistive magnetic head having a magnetoresistive element and a magnetic thin film that guides signal magnetic flux to the magnetoresistive element, in which the magnetic thin film has a structure in which two magnetic thin films are laminated with a non-magnetic intermediate layer interposed therebetween. The occurrence of Barkhausen noise is effectively avoided by energizing at least one of the magnetic thin films in a direction substantially perpendicular to the trunk width direction.

[Conventional technology]

In order to reduce Barkhausen noise in a magnetoresistive magnetic head (hereinafter referred to as an MR effect magnetic head), the magnetoresistive effect is used as disclosed in, for example, Japanese Patent Application Laid-open No. 182620/1983. It has been proposed that an element (hereinafter referred to as an MR effect element) has a structure in which two MR effect magnetic layers are laminated with a nonmagnetic intermediate layer interposed therebetween.

However, even in an MR effect magnetic head using such an MR effect element, an MR effect type magnetic head is provided with a magnetic thin film as a magnetic guide path that picks up and guides signal magnetic flux from a magnetic recording medium to the MR effect element. In this case, Barkhausen noise occurs due to this magnetic thin film.

On the other hand, in Japanese Unexamined Patent Publication No. 57-203979, a magnetic thin film serving as a magnetic conduction path for guiding magnetic flux to an MR effect element has a laminated structure of magnetic layers with a non-magnetic intermediate layer interposed therebetween. There have been proposals for thin film magnetic heads designed to improve Hausen noise. That is, as shown in FIG. 4, a magnetic thin film used as a general magnetic conduction path is usually composed of a high permeability magnetic film such as a single layer magnetic layer, for example, a permalloy or an amorphous magnetic layer. In the case of a layered magnetic layer, the easy magnetization axes e and a directions are selected in a direction perpendicular to the direction of the signal magnetic field Hs force applied from the magnetic recording medium, that is, in the trunk width direction. In this case, in order to maintain a state in which the sum of magnetostatic energy due to magnetic anisotropy energy, shape anisotropy, etc. is minimum for the entire layer, the magnetic domain structure is rectangular as shown in Figure 4. In other words, in the magnetic film (5) of the single-layer magnetic layer, magnetic domains (52) whose magnetization directions are alternately opposite are generated along the short side direction in the plane thereof, and a closed loop is formed with respect to these adjacent magnetic domains (52). Along the long side direction of the magnetic layer between both ends, that is, along the hard magnetization axis, and along the a direction, magnetic domains (53) in opposite directions are created.
is occurring. In this configuration, the signal magnetic field Hs from the magnetic recording medium during reproduction is applied in the a-direction, along the hard-to-magnetize axis of the single-layer magnetic layer, that is, the magnetic film (5), as described above. Since the magnetic head operates according to the following, Barkhausen noise does not occur much. However, as the density of recorded information increases, the track becomes narrower, and as the width of the magnetic film (5) becomes narrower, the shape magnetic anisotropy increases, so the overall magnetic The direction of anisotropy is inclined from the trunk width direction, that is, the width direction of the magnetic film, to a direction perpendicular thereto. As a result, the movement of the magnetic walls (54) and (55) is included in the magnetic head operation, causing an increase in Barkhausen noise and a decrease in S/H.
This is disadvantageous in terms of signal processing.

On the other hand, in the magnetic film disclosed in JP-A-57-203979, a non-magnetic intermediate layer (10) is interposed as shown in FIG.
By adopting a structure in which 1) and (12) are laminated, the magnetization directions of both the upper and lower magnetic layers (11) and (12) are made antiparallel to each other as shown by the arrows Ml and M2. To avoid Barkhausen noise during reproduction, the magnetic field from the magnetic recording medium is oriented in the direction of the hard magnetization axis and applied to a, so that the magnetic head operation is performed by a rotational magnetization process, thereby reducing Barkhausen noise during reproduction. That's what I do.

In a thin-film magnetic head using a magnetic film with such a laminated structure, the effective trunk width Wt of the single-layer structure shown in FIG. The advantage is that the effective track width is enlarged compared to the limited narrow width area in the center of the track.

However, even when using a magnetic film with such a laminated structure of two magnetic layers, as the track width on the magnetic recording medium becomes narrower, the magnetic film (5) becomes narrower. Along with this, the shape anisotropy becomes dominant, and the direction of the overall magnetic anisotropy also tilts away from the trunk width direction.

As a result, there is a problem in that domain walls are generated by the signal magnetic field IIs obtained from the magnetic recording medium, resulting in Barkhausen noise.

[Problem that the invention seeks to solve]

As described above, the present invention provides an M
In an R effect type magnetic head, Barkhausen noise in the magnetic film is effectively improved by narrowing the track width, thereby improving the effective trunk width and, therefore, the reproduction output characteristics.

Means for Solving Problem c] In the present invention, as shown in FIG.
), and a magnetoresistive head having a magnetic thin film (2) that guides a signal magnetic flux to the MR effect element (1),
The magnetic thin film (2) is interposed between two magnetic layers (11) and (1
2) has a laminated structure, and these two magnetic layers (
A current i is passed through at least one of (11) and (12) in a direction substantially perpendicular to the track width direction.

The thickness t of the non-magnetic intermediate Jif (10) in this magnetic film (2) is selected to be, for example, 5≦t≦1000, so that the Coulomb interaction is stronger than the exchange interaction between the two magnetic layers (11) and (12). The thickness is selected to be such that it occurs predominantly and can be sufficiently ignored as a magnetic gap.

[Effect]

As mentioned above, in the present invention, the magnetic film +2) is a non-magnetic intermediate! By adopting a structure in which the magnetic layers (11) and (12) are laminated with (1,0) interposed therebetween, the Barkhausen noise as described at the beginning can be improved.

In addition, by energizing this, even when the width is narrowed to create a narrow track, both magnetic layers (11) and (12) are energized by applying current i, as shown in FIG. A magnetic field along the track width direction is generated in the magnetic layers (11) and (12), which causes magnetizations M1 and M2 that are antiparallel to each other to occur in the magnetic layers (11) and (12). The directional effects are substantially eliminated and the occurrence of Barkhausen noise is effectively avoided. Furthermore, narrowing of the effective track width due to shape anisotropy is also avoided.

〔Example〕

An example of the thin film magnetic head according to the present invention will be explained in more detail with reference to FIG. In the figure, (20) shows this thin film magnetic head as a whole. (21) is a magnetic recording medium such as a magnetic disk, a magnetic sheet, or a magnetic tape, and (22) represents a surface that is in contact with or faces the magnetic recording medium. In this example, the board (
3) For example, Mn-Zn ferrite or Ni-Z
A magnetic substrate such as n-type ferrite is prepared, and this magnetic substrate (
3) is electrically conductive, a thin insulating film (4) of SiO2 or Al2O3 is formed on its surface by vapor deposition, sputtering, etc., and on top of this a thin insulating film (4) of SiO2 or Al2O3, etc. For example, a bias magnetic field generating conductor (5) for applying a bias magnetic field to the band-shaped MR effect element fil extending along the trunk width direction is deposited at a position set back a required distance from ). This conductor (5) can be formed into a desired pattern by forming a conductive layer by, for example, full-surface vapor deposition or sputtering, and by photolithography.

This conductor (5) is then covered with similar insulation [! 1iI
(41), and for example, the MR effect element (1) is arranged and formed on this conductor (5) with an insulating film (2) interposed therebetween.

(2F) and a rear magnetic film (2B) are arranged.

The front end surface of the front magnetic film (2F) faces the magnetic recording medium or facing surface (22), and the rear end faces the element (2F).
11 and arranged in a strip shape so as to be stacked and magnetically coupled to each other.

The rear magnetic film (2B) has its front end laminated and magnetically coupled to the rear end of the element (1), and its rear end is layered with the conductor (5).
For example, the insulating film (4) on the substrate (3) is arranged so as to be closely magnetically coupled with the magnetic substrate (3) at the rear of the arrangement part.
), and through this, the rear magnetic film (2B
) may be formed into a strip shape such that its rear end is directly connected to the substrate (3).

A working magnetic gap g having a required gap length is formed between the front end of the front magnetic film (2F) and the substrate C2 by interposing a non-magnetic gap spacer (6) made of, for example, an insulating film (4). do.

The magnetic films (2F) and (2B) have the required thickness t, for example, t=100 non-magnetic intermediate layers (l
The structure is such that conductive soft magnetic layers (11) and (12) are laminated with O) interposed therebetween. The non-magnetic intermediate layer (10) is, for example, 5
i02+ Ta205. It can be formed by an inorganic insulating nonmagnetic layer such as Al2O3 or a nonmagnetic metal layer such as TjI Mo or Au+4g. The magnetic layers (11) and (12) are made of soft magnetic material such as permalloy or Fe-
Ni alloy or sendust, ie, Fe-Al-trilayer alloy, or soft magnetic amorphous, such as Co-based amorphous, metal such as Co, Fe-Ni, etc., and B.

Alloy with metalloid such as C, St, or CO or Fe-Ni metal, Zr, Nb + Ta,
It can be formed from a metal-metal Co-based amorphous material such as W.

These magnetic layer (11), non-magnetic intermediate layer (10) and upper magnetic layer Ji! 1 (12) can be sequentially deposited over the entire surface by sputtering, vapor deposition, etc., and formed into a desired pattern by photolithography.

These magnetic films (2F) and (2B) are located at the front end of the front magnetic film (2F) and the rear end of the rear magnetic film (2B), respectively.
Electrical connection electrodes (31) and (32) for passing current i through at least one magnetic N (12) or (11) are electrically connected and deposited, and further magnetic films (2F) and (2B) A connecting conductor (33
) is provided to supply a current between both electrodes (21) and (22). In this case, the front electrode (21) is on the ground side,
By doing so, it is desirable to prevent corrosion from occurring due to battery action when another object comes into contact with the surface (21).

In addition, in these magnetic films (2F) and (2B), the non-magnetic intermediate layer (10) has conductivity, or both magnetic layers (11)
and (12), if the thickness is so thin that electrical insulation cannot be maintained between the electrodes (21) and (22), both magnetic layers (11) and (12) are simultaneously moved in the same direction by applying current between the electrodes (21) and (22). For example, as shown in the figure, a current i can be passed from the rear end to the front end.
10) is an insulating material and has a large thickness, and the magnetic layer (
When electrical insulation between 11) and 12 is to be achieved, for example, a window is formed in advance in the non-magnetic intermediate layer under the electrodes 21 and 22, so that the lower magnetic layer 11
It is desirable that an upper magnetic layer (12) be deposited thereon in electrical connection.

Then, on the substrate (1), the conductor (5), the magnetic thin film (5F) (5B), and the MR effect element (1),
An upper substrate (35) made of a magnetic material, for example, is bonded to the main body of the thin film magnetic head on which the power supply electrodes (31) and (32) are formed, through an adhesive (34) such as glass, and both substrates (35) are bonded together. ) and (3), the thin film magnetic head body is protected and, in some cases, a magnetic shielding effect is obtained.

The MR effect element (1) may also have a laminated structure of two magnetic layers N (41) and (42), at least one of which has an MR effect, with a non-magnetic intermediate layer (40) interposed therebetween.

Further, the surface (22) that faces or faces the magnetic recording medium is formed by polishing the entire area from the substrate (3) to the upper substrate (35). Then, a first
In the figure, a magnetic recording medium (21) such as a magnetic disk, a magnetic sheet, a magnetic tape, etc. is relatively moved in a direction along the plane of the paper, for example, from the top to the bottom of the figure, or in the opposite direction.

According to such a configuration, a closed magnetic path of magnetic thin film (2F>-MR effect element (1) - magnetic thin film (2B) - one substrate (3) - operating magnetic gap magnetic thin film (2F) is formed, and magnetic recording A magnetic head is configured in which a signal magnetic flux from a medium (21) is applied to an MR effect element (1) through at least magnetic thin films (2F) and (2B).

(+51) and (+52) are electrodes provided at both the front and rear ends of the MR effect element (1), and a sense current is applied between these electrodes (+51) and (+52).

In the example of FIG. 1, both magnetic thin films (2F) and (2B)
This is a case where a conductor (33) is provided between the two to electrically connect them, but in this case, as shown in FIG. The electrodes (+51) and (+52> of the MR effect element (1) are omitted, and the magnetic thin film (2
A sense current to the element (11) is passed between the electrodes (31) and (32) of F) and (2B), thereby causing the magnetic thin film (
2F) and (2B) may also be used for energizing.

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

Furthermore, on each side shown in the figure, the case is that both the magnetic layers (11) and (12) constituting the magnetic thin films (2F) and (2B) are respectively energized, but one magnetic layer (11) is energized. ) or (12) is energized to generate magnetization in the track width direction in the other magnetic layer (12) or (11), and the magnetic field caused by this magnetization causes antiparallel magnetization of the energized one. It can also be made to occur in the magnetic layer.

Further, as mentioned above, in the present invention, a magnetic thin film (2
F) and (2B) at least as a pair of magnetic 7! (11) and (12), but in some cases, a three-layer structure with a non-magnetic intermediate layer is used, and the thickness of the central magnetic layer is increased to form a layer with the magnetic layers on both sides. It is also conceivable to construct a structure with three or more magnetic layers, such as a structure in which mutually antiparallel magnetic fields are generated between them.

Furthermore, the magnetic layer (
For 11) and (12), it is preferable to use magnetic materials of the same material, that is, materials with the same coefficient of thermal expansion.When doing so, the laminate may suffer from changes in properties or peeling due to thermal strain due to the difference in coefficient of thermal expansion. etc. are avoided.

Further, the present invention is not limited to the above-mentioned examples, but also applies to various MR effect type magnetic heads having a magnetic thin film that constitutes at least a part of a magnetic guide path that supplies signal magnetic flux from a magnetic recording medium to an MR effect element, such as the above-mentioned As in the example, the recording signal magnetic field from the magnetic recording medium is picked up from the front end face of the magnetic thin film facing the magnetic recording medium or facing the magnetic recording medium, regardless of the operating magnetic gap g, and is transmitted to the MR effect element (1). The present invention can also be applied to an MR effect type magnetic head or the like that adopts a structure in which the magnetic field is guided.

〔Effect of the invention〕

As described above, in the present invention, the magnetic thin films (2F) and (2B) constituting at least a part of the magnetic path in the MR effect magnetic head are connected to the magnetic layer through the nonmagnetic intermediate layer (10). (11) and (12) are laminated, and they are particularly energized so that the magnetic field generated by this energization generates magnetization that avoids the effects of shape magnetic anisotropy, thereby reducing Barkhausen noise. Even when the track width is narrowed, it can be made sufficiently small.
By improving the S/N ratio, it is possible to obtain advantages in signal processing.

[Brief explanation of the drawing]

1 and 3 are respectively enlarged linear cross-sectional views of each side of the MR effect type magnetic head according to the present invention, FIG. 2 is an enlarged perspective view showing an example of the magnetic thin film, and FIGS. 4 and 5 are FIG. 2 is an enlarged perspective view illustrating a magnetic thin film in a conventional magnetic head. +11 is an MR effect element, (2F) and (2B) are magnetic films, (10) is its nonmagnetic intermediate layer, (11) and (12)
is the magnetic layer.

Claims (1)

[Scope of Claims] A magnetoresistive magnetic head having a magnetoresistive element and a magnetic thin film that guides a signal magnetic flux to the magnetoresistive element, wherein the magnetic thin film has two magnetic layers with a nonmagnetic intermediate layer interposed therebetween. 1. A magnetoresistive magnetic head comprising a plurality of magnetic layers, characterized in that a current is passed through at least one of the two magnetic layers in a direction substantially perpendicular to the track width direction.