JPH08273124A - Spin valve film - Google Patents

Abstract

PURPOSE: To increase the variation of the magnetic resistance of a spin valve film for a magnetoresistance effect element made of a laminated film with a four-layered film consisting of a 1st magnetic layer, a nonmagnetic layer, a 2nd magnetic layer and a magnetization fixing layer as the basic structure and to reduce hysteresis due to coercive force in a low magnetic field. CONSTITUTION: When the 1st magnetic layer is made of a Co-NiFe multilayered film, a high variation of magnetic resistance and low coercive force can be attained. When the 2nd magnetic layer is also made of a Co-NiFe multilayered film or is made of a Co layer, such effects are stably produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a spin valve film forming a spin valve type magnetoresistive effect element used in a magnetic disk device for a high density magnetic recording device, a magnetic encoder device or the like. The present invention relates to a spin valve film that achieves an improvement in magnetoresistance change rate and a reduction in hysteresis due to coercive force in a low magnetic field by using a multilayer film of a Co layer and NiFe having a specific laminated structure.

[0002]

2. Description of the Related Art The magnetoresistive effect is the so-called permalloy (Ni
It utilizes the fact that the resistance value changes depending on the angle formed by the magnetization direction and the direction of the sense current in a thin film such as Fe). Since it senses the magnetic flux itself, it is expected to replace the conventional inductive head. There is. However, Ni
Magnetoresistance change rate (MR) of a magnetoresistance effect element using Fe
The ratio) is at most about 2%, and it is necessary to improve the MR ratio and the sensitivity of the magnetoresistive effect element in order to further improve the recording density.

In such a magnetoresistive effect element, the sensitivity can be increased by using a spin valve type magnetoresistive effect element as disclosed in Japanese Patent Laid-Open No. 4-358310. In the spin valve magnetoresistive effect element, the first magnetic layer / nonmagnetic layer / second magnetic layer /
The four-layer structure of the magnetization fixed layer is basically used, and the magnetization direction of the second magnetic layer is fixed by the magnetization fixed layer.
The magnetic layer changes the direction of magnetization by a signal magnetic field from the outside, and the electric resistance changes depending on the angle formed by the magnetizations of the two ferromagnetic metal layers. The element end portion is detected to detect the change in electric resistance. The reproduction signal is detected by the pair of electrodes formed on the substrate.

Further, since the magnetoresistive effect decreases as the magnetoresistive effect film becomes thinner, see, for example, “J.
Appl. Phys. , Vol. 69 no.
8, p 4774-4779 (1991) ”, Fe
Mn is used as the magnetization fixed film of the NiFe film, and non-magnetic C
There is an attempt to obtain a large magnetoresistive effect by utilizing the fact that the magnetoresistive effect changes depending on the direction of magnetization with the other free NiFe film sandwiching u.

[0005]

However, NiF
When the e film is used for the magnetic layer, the hysteresis due to the coercive force in a low magnetic field is small, but the magnetoresistance change rate is about 4%, and a higher magnetoresistance change rate is desired. Further, when Co is used for the magnetic layer, the change in magnetoresistance is as large as about 8%, but the hysteresis due to the coercive force in a low magnetic field is as large as about 20 Oe, so that it can be used as a magnetoresistive head. It's a big problem.

The present invention, as described above, includes the first magnetic layer /
In view of the present state of the spin valve film for a magnetoresistive effect element, which is composed of a laminated film having a four-layered film of a non-magnetic layer / second magnetic layer / magnetization fixed layer as a basic structure, improvement of the magnetoresistive change rate and protection in a low magnetic field are considered. It is an object of the present invention to provide a spin valve film that achieves a reduction in hysteresis due to magnetic force.

[0007]

The inventor has made various studies on the laminated structure of a spin valve film for the purpose of improving the magnetoresistance change rate and reducing the coercive force in a low magnetic field. As a result, at least the first magnetic layer is made of Co. It was found that, by forming a multilayer film of a NiFe layer and a NiFe layer, the magnetoresistance change is as high as that of a spin valve film using a Co layer, and the coercive force in a low magnetic field is about the same as a spin valve film using a NiFe layer. , Completed this invention.

That is, the present invention provides a spin valve film for a magnetoresistive effect element comprising a laminated film having a four-layer film of a first magnetic layer / a non-magnetic layer / a second magnetic layer / a magnetization fixed layer as a basic structure. Each of the first magnetic layer and the second magnetic layer is composed of a multilayer film of a Co layer and NiFe.
A spin valve film having a layer thickness of 3Å to 8Å and a total Co film thickness of 12Å or more.

Further, the present invention provides a spin valve film for a magnetoresistive effect element comprising a laminated film having a four-layer film of a first magnetic layer / nonmagnetic layer / second magnetic layer / magnetization pinned layer as a basic structure. One magnetic layer is composed of a multilayer film of a Co layer and NiFe, and each Co layer in the multilayer film has a thickness of 3Å to 8Å and a total Co film thickness of 12Å or more, and the second magnetic layer is a Co layer only. The spin valve film is characterized in that

[0010]

The operation of the spin valve film according to the present invention will be described together with the structure of the multilayer film of Co and NiFe and the reasons for limiting the Co film thickness and the Co layer film thickness. In the laminated film having a four-layer film of the first magnetic layer / non-magnetic layer / second magnetic layer / magnetization pinned layer of the present invention as a basic structure, by forming the first magnetic layer from a Co and NiFe multilayer film, A change in magnetic resistance and a low coercive force can be achieved, and at the same time, a stable effect can be obtained by forming the second magnetic layer from a Co and NiFe multilayer film, or by forming the second magnetic layer as a Co layer. can get.

Regardless of which of the first magnetic layer and the second magnetic layer or the magnetic layer of the first magnetic layer is composed of a multilayer film of a Co layer and NiFe, the thickness of each Co layer is less than 3Å. The number of Co atomic layers is about two layers, and there are many porous portions, and there is little effect of improving the magnetoresistance change rate.
If it exceeds Å, the effect of improving the magnetoresistive change rate is high, but the crystal magnetic anisotropy oriented in the C-axis appears and the hysteresis becomes large, which is not preferable. To do.

If the total film thickness of Co in each of the first magnetic layer and the second magnetic layer or only the first magnetic layer is less than 12 Å, the obtained magnetoresistive change rate is unstable and the Co layer is Even when a thin layer is inserted between NiFe / Cu, the total film thickness of Co must be 12 Å or more in order to obtain a stable magnetoresistance change rate.

In the present invention, the first magnetic layer is made of Co and N.
When the iFe multilayer film and the second magnetic layer are composed of a Co layer,
The thickness of the Co layer of the second magnetic layer is preferably 20Å to 40Å in consideration of the magnitude of the exchange interaction magnetic field with the magnetization fixed layer. Further, as the non-magnetic layer, Cu, which has low electric resistance, or Ni, which has low reactivity with NiFe and Co, is preferable.
As the magnetization fixed layer, FeM having a large exchange interaction magnetic field
Antiferromagnetic materials such as n or NiO having excellent corrosion resistance are preferable.

[0014]

【Example】

Example 1 A first magnetic layer (90Å) was formed on a glass substrate having a size of 2 inches.
/ Cu (25Å) / second magnetic layer (36Å) / FeMn
When manufacturing a spin valve film having a (100 Å) laminated structure, an RF sputtering apparatus was used for each of the first magnetic layer and the second magnetic layer of NiFe or Co, and the combination of Co and NiFe multilayer films. A film was formed. Sputtering is 500 W in a unidirectional magnetic field, Ar gas pressure is 1 mTo
performed at rr.

The results obtained by measuring the magnetoresistance change rate of various obtained spin valve films and the hysteresis due to the coercive force of the first magnetic layer in the range of ± 50 Oe by the four-terminal method are shown in Table 1.
Table 1 shows the configurations of the magnetic layer and the second magnetic layer. The multilayer film of Co and NiFe has a high magnetoresistance change rate, a small hysteresis, and good characteristics, and as a combination thereof, the first magnetic layer and the second magnetic layer are simultaneously formed into a multilayer film, or The magnetic layer is a multilayer film, and the second magnetic layer is C
It can be seen that only the combination of the o layers is good.

Example 2 R under the same conditions as in Example 1 on a 2-inch square glass substrate.
1st magnetic layer / Cu (26Å)
/ Second magnetic layer / FeMn (100 Å) laminated structure, two kinds of spin valves in which the first magnetic layer and the second magnetic layer are multilayer films, the first magnetic layer is a multilayer film and the second magnetic layer is a Co layer When forming the film, the Co thickness of the multilayer film was changed variously. The hysteresis resulting from the magnetoresistance change rate of the various spin valve films and the coercive force of the first magnetic layer was ± 50 O
Table 2 shows the results of measurement by the 4-terminal method in the range of e together with the configurations of the first magnetic layer and the second magnetic layer.

In a spin valve film having a Co film thickness of less than 3Å in the multilayer film, the hysteresis is small, but the change in magnetoresistance change is small, and the merit of multilayering is small, and the Co film thickness of the multilayer film exceeds 8Å. In the spin valve film, the change in the magnetoresistance change rate is large, but the hysteresis is also large, and the merit of multilayering is small.
The spin valve film having a Co film layer of 3Å to 8Å per layer is
It was confirmed that the change in the magnetoresistance change was large, the hysteresis was small, and the characteristics were good.

EXAMPLE 3 [NiFe having a stacking number of n was formed on a 2-inch square glass substrate.
(10Å) / Co (4Å)] / Cu (2Å) / Co (3
5Å) / NiO (250Å) laminated structure and [NiFe (24Å) / Co (4Å)] / Cu (26
In manufacturing two kinds of spin valve films having a laminated structure of Å) / Co (35Å) / NiO (250Å), the number n of Co layers in the multilayer film was set to 1 to 4 and RF under the same conditions as in Example 1 was used. Film formation was performed using a sputtering device, and the effect of the total Co film thickness in the multilayer film was examined.

The results obtained by measuring the magnetoresistance change rate of various obtained spin valve films and the hysteresis due to the coercive force of the first magnetic layer in the range of ± 50 Oe by the four-terminal method are shown in Table 1.
Table 3 shows the configurations of the magnetic layer and the second magnetic layer. In any of the laminated structures, the magnetic resistance change rate is small when n ≦ 2, and the magnetic resistance change rate is stable when n = 3 or more. This indicates that the magnetoresistance change rate is unstable in a spin valve film having a total Co film thickness of less than 12 Å, and is stable even when a thin Co layer is inserted between NiFe / Cu. In order to obtain the above-mentioned magnetoresistive change rate, the Co layer must be thickened, and the coercive force becomes large. Therefore, the multi-layered magnetic layer of the present invention aims at high magnetoresistive change rate and low coercive force. To be achieved.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

The present invention is a spin valve laminated film having a four-layer film of a first magnetic layer / a non-magnetic layer / a second magnetic layer / a magnetization fixed layer as a basic structure. By forming the magnetic layer from a Co and NiFe multilayer film,
It becomes possible to achieve a high magnetic resistance change and a low coercive force, and at the same time, the second magnetic layer is also composed of a Co and NiFe multilayer film, or the second magnetic layer is a Co layer.
A stable effect can be obtained.

Claims (2)

[Claims] 1. A spin valve film for a magnetoresistive effect element comprising a laminated film having a four-layer film of a first magnetic layer / a non-magnetic layer / a second magnetic layer / a magnetization fixed layer as a basic structure, the first magnetic layer,
Each of the second magnetic layers is composed of a multilayer film of a Co layer and NiFe, and the thickness of each Co layer in each multilayer film is 3Å to 8Å
And a total Co film thickness of 12 Å or more. 2. A spin valve film for a magnetoresistive element, comprising a laminated film having a four-layer film of a first magnetic layer / a non-magnetic layer / a second magnetic layer / a magnetization fixed layer as a basic structure, wherein the first magnetic layer is It is composed of a multilayer film of a Co layer and NiFe, and each Co layer in the multilayer film has a thickness of 3Å to 8Å and a total Co film thickness of 1
A spin valve film having a thickness of 2 Å or more, wherein the second magnetic layer is composed of only a Co layer.