JPH10198926A - Magnetoresistive effect magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistive effect magnetic head without a Barkhousen noise and improving the soft magnetic characteristic of a magneto resistive effect film by making the ferromagnetic film a laminated film between a film having negative or zero magnetostriction and a film having positive or zero magntostriction, and making the absolute value of the magnetostriction of the ferromagnetic film a specified value or below in the magnetoresistive effect film of a spin valve structure. SOLUTION: The magneto resistive effect film 20 of the spin valve structure is constituted of a first ferromgnetic film 21, a non-magnetic conductive film 22, a second ferromagnetic film 23 and an anti-ferromagnetic film 24. The intrasurface magnetization of the first ferromagnetic film 21 and second ferromagnetic film 23 are turned in the directions tilting by 90 deg. to each other in the state that an external magnetic field isn't applied. The magnetization of the first ferromagnetic film 21 is rotated freely, and thus, a resistance change occurs, and an output is generated. Then, the first ferromagnetic film 21 consists of a third ferromagnetic film 25 having the negative or zero magnetostriction and a fourth ferromagnetic film 26 having the positive or zero magnetostriction. Then, the absolute value of the magnetostriction of the first ferromagnetic film is required to be 4×10<-7> or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetoresistive head.

[0002]

2. Description of the Related Art With the increase in density of magnetic recording, a high-sensitivity reproducing head is required. As the reproducing head, a magneto-resistive head utilizing a magneto-resistive effect (hereinafter, MR) is used. I have. An MR head currently mounted on a magnetic disk device uses an anisotropic magnetoresistance effect in which resistance changes depending on an angle between a direction of magnetization of a magnetic film and a signal detection current. In the MR head, a NiFe film is used in a portion (magnetic sensing portion) where the resistance is changed by sensing an external magnetic field, and its magnetoresistance change rate is about 3% at the maximum. For this reason, when the areal recording density becomes as high as several Gb / in ² , it is expected that the MR head using this anisotropic magnetoresistive effect will become insufficient in sensitivity, and a magnetic head exhibiting a more sensitive magnetoresistive change is required. ing.

In recent years, Co / Cu, Fe / Cr or Ni
It has a multilayer structure in which ferromagnetic films and non-magnetic conductive films are alternately laminated like Fe / Cu, and a giant magnetoresistance effect (about 50%) utilizing antiferromagnetic coupling between ferromagnetic films. Was reported to be obtained. However, the saturation magnetic field required to obtain this magnetoresistance change rate is as high as several kOe, which is difficult to apply to an actual MR head.

On the other hand, two ferromagnetic films are separated by a nonmagnetic conductive film, an antiferromagnetic film is adjacent to one ferromagnetic film to fix the direction of magnetization, and the other ferromagnetic film is It has been reported that the magnetization is reversed by a magnetic field, and a high magnetoresistance change can be obtained depending on the angle between the magnetization directions of the two ferromagnetic films (Japanese Patent Laid-Open No. 7-62534). This is called a spin valve structure, which is saturated with a relatively small magnetic field, and is currently receiving the most attention as a next-generation magnetoresistive film for a magnetic head.

The spin valve film has a different magnetoresistance ratio and magnetic characteristics depending on the material of the ferromagnetic film. For example, Co / Cu / Co described in JP-A-7-652852 is disclosed.
In the case of (1), the magnetoresistance ratio is as high as about 8%, but the coercive force is as large as 20 Oe, and the soft magnetic properties are not good. Also Ni
In the case of Fe / Cu / NiFe, the coercive force is about 1 Oe and the soft magnetic properties are good, but the magnetoresistance ratio is as low as about 4%. Furthermore, a spin valve structure using CoFe and NiFeCo for a ferromagnetic film has also been reported, which has a higher magnetoresistance ratio and a better soft magnetic property than those using Co or NiFe. Have been.

However, these reports do not mention the magnetostriction of the ferromagnetic film. If the value is large, the film becomes susceptible to the film stress after the device is formed into an element, and a domain wall is generated to reduce Barkhausen noise. The problem of occurring occurs. FIG. 4 shows the relationship between the composition of CoFe and the magnetostriction. The magnetostriction of Co is as large as about −25 × 10 to ^7, and the absolute value of CoFe is considerably large, depending on the composition, of the order of 10 to ⁶ . When the Fe content is about 10 wt%, the magnetostriction becomes almost zero. However, recent studies have revealed that CoFe formed on NiFe has a positive magnetostriction depending on the film thickness where the film thickness is small. . FIG. 5 shows Ta (5 nm) formed on a glass substrate.
/ NiFe (5 nm) / CoFe magnetostriction and CoFe film thickness d
The relationship is shown below. The composition of CoFe is 90Co-10F
e (wt%) and 92Co-8Fe (wt%). C
Although the magnetostriction of o-10Fe (wt%) is almost zero when the film thickness is 20 nm or more, the magnetostriction becomes larger as the film thickness becomes smaller, and becomes 14 × 10 to ^{7 at} 3 nm. Similarly, the film of Co-8Fe (wt%) has a magnetostriction of −5 × 10 to ^{7 at} 20 nm, and has a magnetostriction of 9 × 10 to ^{7 at} 3 nm, and the magnetostriction greatly changes from negative to positive. From the viewpoint of coercive force, the film thickness of these Co and CoFe must be 5 nm or less. Co-10Fe (wt%), Co-8Fe
(Wt%) All films are positively large below 5 nm,
It is difficult to reduce magnetostriction only by changing the composition of oFe.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable magnetoresistive magnetic head having a magnetoresistive film having good soft magnetic characteristics and a large magnetoresistance change rate and free of Barkhausen noise. Is to provide.

[0008]

In order to achieve the above object, the present invention provides a unit laminated film comprising a first ferromagnetic film and a second non-magnetic conductive film, and a plurality of unit laminated films. The magnetoresistive film shown in FIG. 1 in which the electric resistance changes depending on the angle between the magnetizations of the ferromagnetic films, and a pair of electrodes for flowing a signal detection current through the magnetoresistive film. Wherein the ferromagnetic film of the unit laminated film comprises a third ferromagnetic film having a negative or zero magnetostriction and a fourth ferromagnetic film having a positive or zero magnetostriction. An absolute value of magnetostriction of the first ferromagnetic film is 4
× 10 to ⁷ or less.

Further, a first ferromagnetic film and a second ferromagnetic film are laminated with a nonmagnetic conductive thin film as an intermediate layer, and the magnetization direction of the first ferromagnetic film is set to the first ferromagnetic film. A spin-valve magnetic head having a magnetoresistive film shown in FIG. 2 fixed by an antiferromagnetic film provided adjacently and a pair of electrodes for flowing a signal detection current through the magnetoresistive film. Wherein at least the second ferromagnetic film is a laminated film of a third ferromagnetic film having a negative or zero magnetostriction and a fourth ferromagnetic film having a positive or zero magnetostriction; The absolute value of the magnetostriction of the magnetic film is set to 4 × 10 to ⁷ or less.

Further, it is desirable to add the following elements when forming the magnetoresistive film.

(1) The absolute value of the magnetostriction of the third and fourth ferromagnetic films is 2 × 10 to ⁶ or less.

(2) The third and fourth ferromagnetic films are made of Ni
Fe alloy, Co or Co alloy.

(3) The Fe content of the NiFe alloy is 1
6 to 24 wt%, and the film thickness is in the range of 1 nm to 10 nm.

(4) The Co alloy is a Co—Fe alloy,
The Fe content is 6 to 14 wt%, and the film thickness of Co and the Co alloy is 5 nm or less.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view of a multilayer laminated film according to the present invention.
FIG. 2 shows a cross-sectional view of the spin valve film.

The magnetoresistive effect film 10 shown in FIG. 1 includes a multilayer film of a ferromagnetic film 11 and a nonmagnetic conductive film 12 as a unit multilayer film, and includes a plurality of layers. According to the present invention, the ferromagnetic film 1
At least one of the ferromagnetic films 15 has a negative or zero magnetostriction and a ferromagnetic film 16 has a positive or zero magnetostriction.
It is composed of Here, the ferromagnetic films 15 and 16 may be stacked in reverse.

The spin-valve magnetoresistive film 20 shown in FIG. 2 is composed of a first ferromagnetic film 21, a nonmagnetic conductive film 22, a second ferromagnetic film 23 and an antiferromagnetic film 24. It is configured. The in-plane magnetizations of the first ferromagnetic film 21 and the second ferromagnetic film 23 are oriented in directions inclined by 90 degrees with respect to each other in a state where no external magnetic field is applied.
Further, the magnetization of the second ferromagnetic film 23 is fixed in a preferable direction by the antiferromagnetic film 24. Due to the magnetic field from the medium, the magnetization of the first ferromagnetic film 21 rotates freely, thereby causing a change in resistance and generating an output. According to the present invention, the first ferromagnetic film 21 includes a third ferromagnetic film 25 having a negative or zero magnetostriction and a fourth ferromagnetic film 26 having a positive or zero magnetostriction. Here, the first ferromagnetic films 25 and 26 may be stacked in the same manner as above. Further, the magneto-resistance effect film 20 is placed on the antiferromagnetic film 24 /
The second ferromagnetic film 23 / non-magnetic conductive film 22 / first ferromagnetic film 21 can also be used.

An embodiment of the present invention using the spin valve type magnetoresistive film 20 will be described below. On the substrate 31,
Base film 3 for improving the orientation of magnetoresistive film 20
2 Ta, 5 nm, and third ferromagnetic film 25, NiF
e5 nm, CoFe2 nm as the fourth ferromagnetic film 26,
Cu 2 nm as the nonmagnetic conductive film 22, CoFe 3 nm as the second ferromagnetic film 24, and C as the antiferromagnetic film
An rMnPt of 30 nm and a protective film of Ta of 5 nm are sequentially formed and patterned in a predetermined shape. Ni at this time
The composition of Fe is determined by the composition and film thickness of CoFe. FIG. 6 shows that the CoFe composition is 90Co-10Fe (wt.
%) Shows the relationship between the magnetostriction (composition) of NiFe and the magnetostriction of a Ta (5 nm) / NiFe (5 nm) / CoFe laminated film formed on glass. As is clear from the figure, in order to reduce the magnetostriction of the laminated film, it is sufficient to change the composition of NiFe to increase the magnetostriction to a negative value. In the present embodiment, the film thickness of CoFe is 2 nm. Therefore, when the composition of CoFe is used, the composition of NiFe is about 83Ni-17Fe.
(Wt%), may be the -15 × 10 ~ ⁷ in the magnetostriction.
Of course, it is not necessary to limit to this composition, and when changing the composition and the film thickness of CoFe, the composition of NiFe may be similarly changed. In order to increase the resistance change rate of the magnetoresistive film 20, one or both of the fourth ferromagnetic film and the second ferromagnetic film may be made of Co.

Next, after a lift-off photoresist layer is formed, a permanent magnet film of CoCrPt 40 nm is laminated,
A vertical bias applying layer 35 is formed. Next, after forming Au 0.2 μm as the electrode film 36, the lift-off resist layer is removed. Further, while applying a magnetic field of 1 kOe in a direction perpendicular to the medium facing surface in a vacuum, a heat treatment is performed at 230 ° C. for 1 hour to magnetize the CrMnPt, which is the antiferromagnetic film 24, thereby producing the GMR head of the present invention.

In this embodiment, CrMnPt is used as the antiferromagnetic film 24 of the spin valve film. However, the present invention is not limited to this, and CrMn-X1 (X1: Pd, A
u, Rh, Ru) can also be used. Further, Fe
A disorder antiferromagnetic film such as a Mn alloy or a MnIr alloy can also be used. In this case, heat treatment at the time of wearing is unnecessary. Further, NiMn, NiMn-X2 (X2: C
o, Ti, Zr, Ru, Rh) may be used, but in this case, a longer time heat treatment is required at a higher temperature than the heat treatment. However, the heat treatment temperature is preferably 260 ° C. or less in consideration of the stability of the characteristics of the spin valve film. In the embodiment, the magnetoresistive film 20 is formed by forming the third ferromagnetic film 25 / fourth ferromagnetic film 26 / nonmagnetic conductive film 22 / second ferromagnetic film 23 from the substrate side.
/ Anti-ferromagnetic film 24 is stacked in this order, but on the contrary, from the substrate side, anti-ferromagnetic film 24 / second ferromagnetic film 23 / non-magnetic conductive film 2
2 / fourth ferromagnetic film 6 / third ferromagnetic film 25. In this case, the antiferromagnetic film 24 may be made of a non-conductive material, for example, NiO. In the present embodiment, CoCrPt, which is a permanent magnet film, is used as the vertical bias application layer, but the invention is not particularly limited to this. For example, an antiferromagnetic film can be used. In this case, a ferromagnetic film needs to be formed as a base film. In this case, the magnetization directions of the antiferromagnetic film 24 for fixing the magnetization of the second ferromagnetic film 23 and the antiferromagnetic film 35 used for the longitudinal bias applying layer are inclined by 90 ° with respect to each other. Therefore, it is necessary to use materials having different blocking temperatures. At this time, the exchange coupling magnetic field between the second ferromagnetic film 23 and the antiferromagnetic film 24 is larger than the exchange coupling magnetic field between the ferromagnetic film and the antiferromagnetic film of the longitudinal bias applying layer 35. Is preferred.

[0022]

According to the present invention, a ferromagnetic film having a negative or zero magnetostriction and a ferromagnetic film having a positive or zero magnetostriction are formed of a multilayer magnetic structure and a spin valve structure utilizing a magnetoresistance effect. The soft magnetic properties can be improved by forming a laminated film with the film and setting the absolute value of the magnetostriction of the ferromagnetic film to 4 × 10 to ⁷ or less. Thus, a highly reliable magnetoresistive head without Barkhausen noise can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetoresistive film according to the present invention.

FIG. 2 is a sectional view of a magnetoresistive film according to the present invention.

FIG. 3 is a cross-sectional view of a magnetoresistive head according to the present invention.

FIG. 4 is a characteristic diagram of Fe composition and magnetostriction of CoFe.

FIG. 5 is a characteristic diagram of the magnetostriction of NiFe / CoFe and the thickness of CoFe.

FIG. 6 shows magnetostriction (composition) of NiFe and NiFe / CoFe.
FIG. 3 is a characteristic diagram of the magnetostriction of FIG.

[Explanation of symbols]

20: magnetoresistive effect film, 22: non-magnetic conductive film, 23,
25, 26: ferromagnetic film, 24: antiferromagnetic film, 30: magnetoresistive head, 31: substrate, 32: base film, 34:
Protective film, 35: vertical bias applying layer, 36: electrode.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Keiji Shigematsu 2880 Kozu, Odawara City, Kanagawa Prefecture, Hitachi, Ltd. Storage Systems Division

Claims (8)

[Claims] 1. A laminated film of a first ferromagnetic film and a second non-magnetic conductive film is a unit laminated film, a plurality of the unit laminated films are laminated, and magnetization of the ferromagnetic films is formed. In a magneto-resistance effect type magnetic head having a magneto-resistance effect film whose electric resistance changes according to an angle and a pair of electrodes for flowing a signal detection current through the magneto-resistance effect film, the first strength of the unit laminated film The magnetic film is a laminated film of a third ferromagnetic film having a negative or zero magnetostriction and a fourth ferromagnetic film having a positive or zero magnetostriction, wherein the absolute value of the magnetostriction of the first ferromagnetic film is A magnetoresistive head having a value of 4 × 10 to ⁷ or less. 2. The magnetoresistive head according to claim 1, wherein the absolute value of the magnetostriction of the third ferromagnetic film and the fourth ferromagnetic film is 2 × 10 to ⁶ or less. 3. The magnetoresistive head according to claim 1, wherein said third ferromagnetic film and said fourth ferromagnetic film are made of NiFe alloy, Co or Co alloy. 4. A first ferromagnetic film and a second ferromagnetic film are laminated with a non-magnetic conductive thin film as an intermediate layer, and the magnetization direction of the first ferromagnetic film is the first ferromagnetic film. A spin-valve magnetoresistive effect type having a magnetoresistive film fixed by an antiferromagnetic film provided adjacent to the film and a pair of electrodes for passing a signal detection current through the magnetoresistive film. In the magnetic head, at least the second ferromagnetic film is a laminated film of a third ferromagnetic film having a negative or zero magnetostriction and a fourth ferromagnetic film having a positive or zero magnetostriction,
The magnetoresistance effect type magnetic head, wherein the absolute value of the magnetostriction of the second ferromagnetic film is 4 × 10 to ⁷ or less. 5. The magnetoresistive head according to claim 4, wherein the absolute value of the magnetostriction of the third ferromagnetic film and the fourth ferromagnetic film is 2 × 10 to ⁶ or less. 6. The first ferromagnetic film, the third ferromagnetic film, and the fourth ferromagnetic film are formed of NiFe and Ni, respectively.
5. The magneto-resistance effect type magnetic head according to claim 4, wherein the magnetic head is made of an FeCo alloy, Co or a Co alloy. 7. The NiFe alloy having an Fe content of 16 to 2
5. The magnetoresistive head according to claim 1, wherein the thickness is 4 wt% and the thickness is in a range of 1 nm to 10 nm. 8. The magnetoresistive effect type according to claim 1, wherein the Co alloy is a Co—Fe alloy, the Fe content is 6 to 14 wt%, and the film thickness of Co and the Co alloy is 5 nm or less. Magnetic head.