JPH09204611A - Magnetoresistance effect type head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistance effect type head in which a bias magnetic field is not affected by a sense current. SOLUTION: A soft magnetic film bias type magnetoresistance effect type head 10 has a magnetoresistance effect element 4 constituted by laminating a magnetic film 1 and a soft magnetic film 3 to hold a non-magnetic film 2 therebetween, thereby having a magnetoresistance effect and two shield members 11, 13 disposed on the upper and lower sides of the magnetoresistance effect element 4. In that case, when a distance between the magnetic film 1 having the magnetoresistance effect and one of the shield members 11 is expressed by g2 and a distance between the soft magnetic film 3 and the other shield member 13 is expressed by g3 , the values of g2 and g3 are set so as to satisfy 1.5×g2 <=g3 <=2×g2 within the range of g2 <=0.3μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head useful for a magnetic recording medium such as a hard disk.

[0002]

2. Description of the Related Art In recent years, in the field of magnetic recording, the recording density has been increasing more and more, and it is strongly demanded that the recording head as well as the recording medium be compatible with the recording density. Thin film heads have been put to practical use.

Also in this thin film head, in order to cope with higher density, a recording operation is performed by a conventional inductive thin film head and a reproducing operation is performed by a magnetoresistive head (hereinafter referred to as an MR head). The recording / reproducing separated type magnetic head, which is described in (1) above, has been put to practical use.

Usually, a magnetoresistive effect element (hereinafter referred to as an MR element) used for an MR head is processed into a strip shape so that the easy magnetization axis direction M _k becomes the longitudinal direction of the element, as shown in FIG. The ferromagnetic thin film 31 having uniaxial anisotropy
Is used, and a constant sense current Is is flowed in the longitudinal direction of the device through the electrodes 32 formed on both ends of the ferromagnetic thin film 31 in the longitudinal direction. When the external magnetic field H _ext is applied in the direction of the hard axis of the MR element 40, that is, in the direction perpendicular to the easy axis of magnetization, the magnetization M is rotated, and the electric resistance value is changed accordingly.

The operating characteristics of the MR element 40 are explained as follows. As shown the relationship between the externally applied magnetic field and the resistance applied to the MR element in Figure 7, the resistance R is changed by a change in externally applied magnetic field H _ext, resistor R is maximum when the external applied magnetic field H _ext is 0 Take R ₀ . The difference between the maximum value R ₀ and the minimum value of the resistance R is ΔR, and ΔR / R ₀ is the rate of resistance change, which is one of the characteristic values of the magnetoresistive effect element.

When such a magnetoresistive effect element is actually used, as shown in FIG. 7, a bias magnetic field _Hb is applied to operate at an operating point B where the resistance is deviated from the maximum point R ₀ . . Then, as shown in FIG. 7, if the externally applied magnetic field H _ext is applied by the input magnetic field signal waveform centered on the magnetic field H _b corresponding to the operating point B, the resistance R also changes accordingly, and the right side in the figure. The output waveform shown in is obtained.

Usually, at the operating point B, the input magnetic field signal waveform and the output waveform have a linear relationship, and an output waveform having a larger amplitude can be obtained for an input magnetic field signal waveform having the same amplitude. The magnitude of the bias magnetic field _Hb is selected. The output waveform having the largest amplitude is obtained when θ = 45 °, where θ is the angle between the direction of the magnetization M of the ferromagnetic thin film and the direction of the sense current Is. Therefore, it is preferable to apply the bias magnetic field H _b so that θ = 45 °.

As a method of applying the bias magnetic field H _b ,
Current bias method, shunt bias method, barber pole method, hard film bias method, soft film (Soft Adjacent La
yer, hereinafter SAL. A bias method and the like have been proposed so far (corresponding to a soft magnetic film in terms of material), but the SAL bias method is predominant because the structure is simple, the fabrication is easy, and a stable bias magnetic field H _b can be obtained. Has become.

The MR element of the SAL bias method has an MR film 2 having a magnetoresistive effect as shown in the schematic diagram of FIG.
1 and a non-magnetic magnetic separation film (non-magnetic film) 22 and a soft magnetic film (SAL) 23 which are adjacent thereto are laminated to form an MR element 30. An electrode 24 for passing the sense current Is is formed thereon.

The MR element 30 includes the MR film 21.
MR element 3 using the magnetic coupling between SAL23 and
The SAL 23 is magnetized by the sense current magnetic field H _i generated by the sense current Is flowing in 0, and the bias magnetic field H _b is applied by the leakage magnetic field. At this time SAL
The direction of the magnetization Ms of 23 is perpendicular to the direction of the sense current.

When the MR element 30 is used in an MR head, a bias magnetic field H applied to the MR film 21 is used.
_{Since b} is used in a saturated state, that is, in a state in which SAL23 is saturated, SAL23 is a sense current Is during use.
Magnetic properties that are saturated by

Further, when the sense current Is is shunted to the SAL 23, the reproduction output is lowered, so that the SAL 23 has a larger resistivity than the MR film 21, and the above-mentioned resistance change rate (ΔR / R ₀ ) is almost the same. It is preferably 0.

MR heads are roughly classified into three types: non-shield type heads, shield type heads, and yoke type heads. The shield type head in which the MR element is sandwiched by the soft magnetic shield members has better frequency characteristics and higher resolution than the non-shield type head. Further, the shield type head has been widely put into practical use because it has a high reproduction output and is easy to manufacture as compared with a yoke type head in which a magnetic flux is guided to an MR element by a yoke material and the MR element is not exposed.

[0014]

When the MR element is used alone, a stable bias magnetic field _Hb can be obtained by applying the above-mentioned SAL bias method.

However, the M of the SAL bias method is
When the R element is applied to a shield type head, the MR element is generally arranged in the center between both shields,
A sense current magnetic field H _i generated by the sense current Is is applied to the MR element via the shield, and the bias magnetic field H _b is applied.
Changes depending on the sense current Is.

This problem becomes more remarkable when the distance g between both shields is narrowed in order to improve the resolution.

In order to solve the above problems, the present invention provides a magnetoresistive head in which the bias magnetic field is not affected by the sense current.

[0018]

A magnetoresistive head according to the present invention comprises a magnetoresistive element comprising a nonmagnetic film sandwiched between a magnetic film having a magnetoresistive effect and a soft magnetic film.
In a magnetoresistive head of a soft magnetic film bias system having two shield members arranged above and below the magnetoresistive element, the distance between the magnetic film having the magnetoresistive effect and one shield member is g ₂ , Assuming that the distance between the magnetic film and the other shield member is g ₃ , g ₂ and g ₃ should satisfy 1.5 × g ₂ ≦ g ₃ ≦ 2 × g ₂ in the range of g ₂ ≦ 0.3 μm. The value of is selected.

According to the above-mentioned constitution of the present invention, 1.5 × g
By setting ₂ ≦ g ₃ ≦ 2 × g ₂ , g ₃ is larger than g ₂ , that is, the magnetic film having the magnetoresistive effect is closer to one shield member, and the soft magnetic film is the other shield member. With this arrangement, it is possible to reduce the dependency of the bias magnetic field on the sense current.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetoresistive head of the present invention will be described with reference to the drawings. SA of the present invention
L-bias type magnetoresistive head (MR head)
As shown in FIG. 1, the MR film 1 is sandwiched on the lower shield member 11 made of a soft magnetic substrate with the magnetic gap film 12 (first non-magnetic insulating film 12a) interposed therebetween.
And a soft magnetic film (SAL) 3 are laminated to form an MR element 4, and the soft magnetic film (SAL) is formed on the MR element 4.
3, an electrode 5 for flowing a sense current Is is formed, a magnetic gap film 12 (second non-magnetic insulating film 12b) is formed so as to cover the MR element 4 and the electrode 5, and a magnetic gap film 12 is formed so as to cover the MR element 4 and the electrode 5. The MR shield 10 is formed by forming the upper shield member 13 made of a magnetic substrate. The electrode 5 is MR
The MR film 1 is deposited so as to cover the side surface of the element 4 and from this side surface.
Is connected with. A sense current Is for sensing the magnetoresistive effect is passed through the electrode 5 to the MR element 4 in parallel with its longitudinal direction.

As shown in the sectional view of FIG. 2, the MR head 10 of this embodiment has a distance M ₂ between the MR element 4 and the lower shield member 11 in the range of g ₂ ≦ 0.3 μm.
In order for the distance g ₃ between the R element 4 and the upper shield member 13 to satisfy 1.5 × g ₂ ≦ g ₃ ≦ 2 × g ₂ ,
The R element 4 has a structure in which it is arranged and formed so as to be displaced from the center of both shield members 11 and 13.

In such a shield type MR head of the SAL bias system, as shown in FIG.
3 due to the magnetic field (sense current magnetic field) H _i generated by
Two magnetic field loops H _i1 , H _i2 and H _i3 occur.

One of these is MR film 1 → SAL3 → M
This is a loop H _i1 called R film 1, but this loop H _i1 is S
When AL3 is saturated, the strength of the magnetic field applied to the MR element 4 remains almost unchanged, and there is no dependence on the sense current Is.

The remaining two are loops H _i2 and H _i3 through the lower shield member 11 or the upper shield member 13 of the MR film 1 → the lower shield member 11 or the upper shield member 13 → the MR film 1, respectively. The lower shield member 11 and the upper shield member 13 do not saturate because of their large volumes.

Therefore, in the shield type MR head of the normal SAL bias system, the magnetic field applied to the MR element 4 has a dependency on the sense current Is as described above due to these loops H _i2 and H _i3 .

When the distance g between the shield members 11 and 13 is large, the effect of these shield members 11 and 13 is small, and the MR element 4 is arranged at the center between the shield members 11 and 13 as in the conventional case. But there is almost no problem.
However, in order to increase the resolution, both shield members 11, 1
The distance g between 3 and reduced, when the distance g ₃ between the distance g ₂ or MR element 4 and the upper shield member 13 with the MR element 4 and the lower shield member 11 is reduced, the shielding member 1
The influence of 1 and 13 becomes large.

[0027] If in FIG. 4 is an MR element in the middle between the two shield members, i.e. when it is g ₂ = g _3, the g ₂ dependence of the angle θ between the magnetization M of the sense current Is and the MR element Show. From FIG. 4, the sense current Is is 6 to 14 mA and θ is within the allowable range of 45 ° ± 5 ° in the range where g ₂ is larger than 0.3 μm, but the sense current Is is smaller when g ₂ is 0.3 μm or less. With the increase, θ becomes large and the bias becomes excessive.

Next, g ₂ is fixed at 0.1 μm, and g ₃
FIG. 5 shows the g ₃ dependence of the angle θ when the angle is changed.
From FIG. 5, θ decreases as g ₃ increases. g
_{When 3} is 0.15 μm or less, if the sense current Is increases, θ
However, when g ₃ is 0.2 μm or more, θ decreases when the sense current Is increases. 0.15μ during this period
When m ≦ g ₃ ≦ 0.2 μm, the dependence of θ on the sense current Is is very small. However, the value of θ is 25 ° to 30 ° and 4
Somewhat smaller than 5 °, the bias magnetic field H _b is slightly too small.

Normally, when the saturation magnetization of SAL is set to be 1 / √2 (about 71%) of the saturation magnetization of the MR element,
θ = 45 °, but in this embodiment, SAL is larger than this value.
It is necessary to increase the saturation magnetization of. This tendency tends to occur even if the value of g ₂ changes, and 1.5 × g ₂ ≦ g ₃ ≦ 2 × g ₂
In the range of, the dependence of θ on the sense current Is is very small.

According to this embodiment, the dependency of the bias magnetic field _{Hb on} the sense current Is is extremely reduced, and a stable bias magnetic field _Hb can be obtained.

The magnetoresistive head (MR head) 10 of this embodiment shown in FIG. 1 can be manufactured, for example, as follows.

First, a base made of a soft magnetic material such as ferrite
A plate is prepared, and this is used as the lower shield member 11. next
The magnetic gap film 1 is formed on the substrate which is the lower shield member 11.
Al that becomes 2_TwoO _Three, SiO_TwoFirst non-magnetic insulating film such as
12a is formed. Thickness of the first non-magnetic insulating film 12a
Is g_TwoIs equivalent to At this time g_TwoIs 0.3 μm or less
To be formed.

Next, N is sputtered on this by sputtering or the like.
MR film 1 made of i-Fe, Al _TwoO_ThreeNon-consisting of etc.
Magnetic film 2 and SAL3 consisting of Ni-Fe-Rh
Form a stack. Then, apply a photosensitive resist material on top of this.
Strip shape that should be applied, exposed and developed, and then formed
Patterned in strip shape corresponding to MR element 4
I do. Using this as a mask, ion milling
From the previously formed MR film 1, non-magnetic film 2 and SAL3
The laminated MR film is etched into a strip-shaped MR element.
Form the child 4.

Next, a photosensitive resist material is applied on the MR element 4 and patterned into the shape of the electrode 5.
At this time, there is no resist only in the region where the electrode 5 is formed. Using this, a conductor film of Ti, Cu or the like is formed by sputtering or the like. After that, the resist is dissolved and removed with a ketone organic solvent (acetone or the like), and the conductor film on the resist is peeled off to form the electrode 5.

Next, a second non-magnetic insulating film 12b such as Al ₂ O ₃ or SiO ₂ to be the magnetic gap film 12 is formed thereon.
Are formed by sputtering or the like. The thickness of the second nonmagnetic insulating film 12b corresponds to g ₃ . At this time, g ₃ is 1.
5 × g ₂ ≦ g ₃ ≦ 2 × g ₂ is satisfied.

Then, a soft magnetic substrate made of ferrite or the like is bonded onto this with an adhesive to form the upper shield member 13. After the thin film head thus formed is cut into individual head chips, the surface to be the sliding surface with respect to the recording medium is polished to expose the MR element 4 to the sliding surface. The MR head 10 is completed through the above steps.

In the above-mentioned embodiment and its manufacturing process, M
In the R head 10, the MR element 4 has a structure in which the MR film 1, the non-magnetic film 2 and the soft magnetic film 3 are laminated in this order, but each layer is formed in the order of the soft magnetic film, the non-magnetic film and the MR film. The MR head of the present invention can be similarly configured even when the MR heads are laminated. Also in this case, by making the positional relationship between the MR element and the upper and lower shield members satisfy the above relational expression of g ₂ and g _3, a stable bias magnetic field can be obtained without being affected by the sense current. .

The magnetoresistive head of the present invention is not limited to the above-mentioned embodiment, and various other structures can be adopted without departing from the gist of the present invention.

[0039]

According to the magnetoresistive head of the present invention described above, the bias magnetic field is hardly affected by the sense current, and a stable bias magnetic field can be obtained. Therefore, according to the present invention, a magnetoresistive head having stable operation characteristics and good performance can be constructed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of a magnetoresistive head of the present invention.

FIG. 2 is a schematic sectional view of an example of a magnetoresistive head of the present invention.

FIG. 3 is a diagram illustrating a magnetic field generated by a sense current in a magnetoresistive head.

FIG. 4 is a diagram showing a relationship between an angle formed by a direction of a sense current and a direction of magnetization of an MR element and g ₂ .

FIG. 5 is a diagram showing a relationship between an angle formed by a sense current direction and a magnetization direction of the MR element and g ₃ .

FIG. 6 is a schematic configuration diagram of a conventional MR element.

FIG. 7 is a diagram showing a relationship between an externally applied magnetic field and a resistance and operation characteristics in the MR element.

FIG. 8 is a schematic configuration diagram of an MR element by a SAL bias method.

[Explanation of symbols]

1, 21 MR film 2, 22 Non-magnetic film 3, 23 Soft magnetic film (SAL) 4, 30, 40 MR element 5, 24, 32 Electrode 10 MR head 11 Lower shield member 12 Magnetic gap film 12a First non-magnetic Insulating film 12b Second non-magnetic insulating film 13 Upper shield member 31 Ferromagnetic thin film Is Sense current H _i Sense current magnetic field H _b Bias magnetic field M Magnetization M _k Magnetization easy axis direction H _ext Externally applied magnetic field

Claims (1)

[Claims] 1. A magnetoresistive effect element comprising a nonmagnetic film sandwiched between a magnetic film having a magnetoresistive effect and a soft magnetic film, and two shield members disposed above and below the magnetoresistive effect element. In the magnetoresistive head of the soft magnetic film bias system having the following, the distance between the magnetic film having the magnetoresistive effect and the one shield member is g ₂ , and the distance between the soft magnetic film and the other shield member is g ₃
In the range of g ₂ ≦ 0.3 μm, 1.5 × g ₂ ≦ g ₃
A magnetoresistive head, wherein the values of g ₂ and g ₃ are selected so as to satisfy ≦ 2 × g ₂ .