JPH03266481A - Magnetoresistance effect film and magnetoresistance effect element provided therewith - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a multilayer magnetic thin film having a high magnetoresistive effect, and particularly to a magnetoresistive film and a magnetoresistive element suitable for a reproducing magnetic head used in a magnetic disk drive or the like.

[Conventional Techniques] Research is progressing on magnetic heads that use magnetoresistive effects as magnetic heads for reproduction in high-density magnetic recording. In order to put a magnetic head with high performance into practical use, it is desirable to develop a magnetic thin film with a high magnetoresistive effect. Recently, Physical Review Letters, Vol. 61, No. 21, pp. 2472-2475 (Physical
Review Letters, Vol. 61. No,
21.2472-2475.1988), an Fe/Cr multilayer film with a resistance change rate of nearly 50% has been reported. [Problems to be Solved by the Invention] However, in order to obtain a resistance change rate of about 50% in the Fe/Cr multilayer film, 20%
A high magnetic field of k Oe or higher must be applied, and as it is, it is difficult to use as a material for magnetoresistive elements that inspect weak magnetic fields from magnetic recording media.
A resistance change rate of about
The resistance change rate at room temperature decreases to about 18%. An object of the present invention is to solve the above-mentioned problems with the Fe/Cr multilayer film, and to provide a magnetoresistive film having a multilayer structure having a high rate of change in magnetoresistance at room temperature and in a low applied magnetic field, and a magnetoresistive element using the same. Our goal is to provide the following.

[Means for Solving the Problems] The present inventors have conducted intensive research on a magnetic thin film that has a multilayer structure with a Fe thin film or an alloy thin film containing Fe as a main component with thin films of other compositions interposed therebetween. It has been revealed that if at least part of the magnetization of the Fe layer or Fe-based alloy layer is antiparallel above and below the intermediate layer in a demagnetized state, a magnetoresistive effect is exhibited, and the present invention has been completed. That is, in a magnetic thin film that has a multilayer structure with an Fe layer or a Fe-based alloy layer interposed through an intermediate layer of another composition, the intermediate layer is paramagnetic and non-insulating, and the F in the demagnetized state is
When at least part of the magnetization of the e layer or Fe-based alloy layer is antiparallel above and below the intermediate layer, and the number of the Fe layers or Fe-based alloy layers is four or more, Fe/Cr
It was revealed that the resistance changes even at lower applied magnetic fields than in the case of multilayer films. Further, the Fe-based alloy layer is made of B or C. 0.1 to 5at of at least one element selected from N
%, the resistance changes even at a lower applied magnetic field. Furthermore, by using the magnetoresistive film of the present invention in a magnetic circuit, a magnetoresistive element that operates with a low applied magnetic field can be obtained.

[Effect]

As mentioned above, in a magnetic thin film that has a multilayer structure with an Fe layer or a Fe-based alloy layer interposed therebetween and an intermediate layer of another composition, the intermediate layer is paramagnetic and non-insulating, and the Fe layer is in a demagnetized state. Alternatively, at least a part of the magnetization of the Fe-based alloy layer is antiparallel above and below the intermediate layer, and the Fe layer or F
When the number of e-based alloy layers is 4 or more, the conventional F
Compared to the e/Cr multilayer film, it shows a change in resistance even with a low applied magnetic field, and the change in electrical resistivity is small, but the change in electrical resistance saturates at a low magnetic field. Furthermore, the rate of change in resistance with respect to a unit magnetic field is also large. This is because the magnetization of the magnetic layer is more easily reversed by an external magnetic field in a multilayer film using a paramagnetic intermediate layer than in a multilayer film using an antiferromagnetic intermediate layer. In a multilayer film using a paramagnetic intermediate layer, the magnetoresistive effect occurs because the magnetization direction of each magnetic layer in the demagnetized state becomes nearly antiparallel due to magnetostatic coupling of each magnetic layer. I can do it.

【Example】

An example of the present invention will be described below in more detail with reference to figures and tables. [Example 1] An ion beam sputtering device was used to produce a multilayer magnetic thin film. Sputtering was performed under the following conditions. Ion gas...Ar Ar gas pressure in the device...2-5X1002Pa Ion gun acceleration voltage for deposition...400V Ion gun ion current for deposition...60mA Distance between target substrates...1
A cross-sectional view of a magnetic thin film of 27 mm produced under the above conditions is shown in FIG. In this example, the main magnetic layer 11 has a film thickness of 500 mm.
A human Fe thin film with a film thickness of 2° as the intermediate layer 12
C and Cr, 7059 manufactured by Corning Corporation as the substrate 13
A glass substrate was used. The total thickness of the multilayer magnetic thin film is approximately 20
00 people, and the number of layers of the main magnetic layer 11 is four. Figure 2 shows the dependence of the electrical resistance of the conventional Fe/Cr multilayer film on the applied magnetic field 21 and the Fe/Ta of the present invention.
The dependence of the electrical resistance of the C multilayer film on the applied magnetic field 22 is shown. The external magnetic field was applied in the direction of easy magnetization in the plane of the multilayer film. The electrical resistance was measured by a four-terminal method, and a current was passed in the direction of easy magnetization in the plane of the multilayer film. Also. Measurements were performed at room temperature. As shown in FIG. 2, the change in electrical resistivity of the Fe/Cr multilayer film is relatively large. However, in order to saturate the change in electrical resistance, a high magnetic field of about 8000e must be applied. In contrast, the Fe/T of the present invention
Although the change in electrical resistivity of the aC multilayer film is small, the change in electrical resistance becomes saturated at a low magnetic field. In addition, the rate of change in resistance per unit magnetic field (the slope of the curve showing the rate of change in resistance in Figure 2) is also larger. This is thought to be because the magnetization of the magnetic layer is more easily reversed by an external magnetic field in the case of a film. In addition, in a multilayer film using a paramagnetic intermediate layer, the magnetoresistance effect occurs because the magnetization directions of each magnetic layer in the demagnetized state are nearly antiparallel due to magnetostatic coupling of each magnetic layer. Seem. As mentioned above, Fe/
The F of the present invention using a paramagnetic intermediate layer rather than a Cr multilayer film
In the e/T a C multilayer film, the change in electrical resistance is saturated at a low magnetic field, and the rate of change in resistance with respect to a unit magnetic field is larger. [Example 2] A magnetic thin film as shown in FIG. 1 was formed under the same conditions as in Example 1. In this embodiment, the main magnetic layer 11 has a film thickness of 50 mm.
A Fe thin film of 0.000000000000 was used, various paramagnetic intermediate layers having a film thickness of 200000 were used as the intermediate layer 12, and a 7059 glass substrate manufactured by Corning Co., Ltd. was used as the substrate 13. The thickness of the entire multilayer magnetic thin film is about 2000, and the number of layers of the main magnetic layer 11 is four. Table 1 shows the change in the maximum resistance change rate depending on the intermediate layer material, and the maximum resistance change rate here indicates the peak value of the curve showing the resistance change rate in FIG. As shown in Table 1, the resistance change rate of multilayer films using TaC, WC, Cu, Ag, and Ti as intermediate layers is relatively large, and these intermediate layer materials have relatively high electrical conductivity. . On the other hand, BN, Si, 5in2. AI□○
The resistance change rate of a multilayer film using No. 1 as an intermediate layer material is small. The rate of change in resistance is expressed as change in electrical resistance Δρ/total electrical resistance ρ, so if a material with high electrical resistance is used as the intermediate layer and the overall resistance increases, the rate of resistance change will decrease. It will be done. Therefore, a non-insulating material is preferred as the intermediate layer material. [Example 3] A magnetic thin film as shown in FIG. 1 was formed under the same conditions as in Example 1. In this example, the main magnetic layer 11 is an Fe thin film, and the intermediate layer 12 is a T a C1 substrate 13 with a film thickness of 20.
A 7o59 glass substrate manufactured by Corning was used as the substrate. The thickness of the entire multilayer magnetic thin film is approximately 2000, and the main magnetic layer 1
The number of layers of 1 was changed. Therefore, the main magnetic layer, that is, Fe
As the number of layers increases, the thickness per Fe layer decreases. The change in the maximum resistance change rate of the multilayer film depending on the number of Fe layers is
As shown in the figure. The maximum resistance change rate here indicates the peak value of the curve showing the resistance change rate in FIG. As the number of Fe layers increases, the maximum resistance change rate increases. In the demagnetized state, the magnetoresistive effect occurs where the magnetization directions of the magnetic layers are antiparallel above and below the intermediate layer. Therefore, it seems that a multilayer film with many intermediate layers and magnetic layers has a larger magnetoresistive effect. As shown in the figure, when the number of Fe layers is four or more, the resistance change rate is 0.5% or more. For this reason, the number of magnetic layers is preferably four or more. [Example 4] A magnetic thin film as shown in FIG. 1 was formed under the same conditions as in Example 1. In this embodiment, the main magnetic layer 11 has a film thickness of 50 mm.
0 Fe-C alloy thin film, Fe-B alloy thin film, Fe
- N-based alloy thin film, T a of 20 people as the intermediate layer 12
As the C1 substrate 13, a 7059 glass substrate manufactured by Conning was used. The thickness of the entire multilayer magnetic thin film is about 2000, and the number of layers of the main magnetic layer 11 is four. The change in the maximum resistance change rate due to the concentration of B, C, and N is expressed as the fourth
As shown in the figure. As shown in the figure, B, C, and N are added to Fe in an amount of 0.
Adding 1 at % or more increases the maximum resistance change rate. However, if more than 5 at % of B, C, and N are added, the maximum rate of resistance change will decrease. B, C, N 0.1
The reason why the maximum rate of change in resistance increases when adding ~5 at% is considered to be as follows. 0.1 of B, C, and N to Fe
When ~5 at% is added, the coercive force becomes lower than that of Fe, as shown in FIG. This is thought to be because the dispersion of the magnetic anisotropy of the magnetic layer becomes smaller, and the magnetization directions of the magnetic layer above and below the intermediate layer become more antiparallel. [Example 5] A magnetoresistive element was formed using the magnetoresistive film of the present invention. The process for forming the magnetoresistive element will be described below. As shown in FIG. 6(a), an L-shaped lower electrode 61 is formed. In this example, the lower electrode 61 was formed of Cu. Next, as shown in FIG. 6(b). A magnetoresistive film 62 of the present invention is formed on the lower electrode 61. In this example, the Fe/TaC multilayer film of Example 1 was used as the magnetoresistive film 62. Next, as shown in FIG. 6(c), an insulator 63 is formed to eliminate the step difference in the magnetoresistive film 62. In this embodiment, resin was used as the insulator 63. Furthermore, as shown in FIG. 6(d), the magnetoresistive film 62 and the insulator 63
An upper electrode 64 was formed thereon. In this example, Cu
The upper electrode 64 was formed by the following steps. A current is passed from the lower electrode 61 to the upper electrode 64. Furthermore, a magnetic field was applied to the magnetoresistive film 62 to examine changes in electrical resistance due to the magnetic field. As a result, in the magnetoresistive element of this example, a maximum change in electrical resistance of 0.6% was observed. Further, the magnetoresistive element of the present invention has a
The value of electrical resistance was saturated with an external magnetic field of 0e. This is F
The magnetic field is lower than that of the e/Cr multilayer film. Furthermore, when forming a magnetoresistive film having a multilayer structure into a device as in this embodiment, it is important to flow the current so that it always passes through the intermediate layer, as in this embodiment.

【Effect of the invention】

As explained in detail above, in a magnetic thin film having a multilayer structure with an Fe layer or an Fe-based alloy layer interposed through an intermediate layer of another composition, the intermediate layer is paramagnetic and non-insulating,
In the demagnetized state, at least a part of the magnetization of the Fe layer or Fe-based alloy layer is antiparallel above and below the intermediate layer, and
When the number of layers or Fe-based alloy layers is 4 or more,
It was revealed that the resistance changes even at low applied magnetic fields. Furthermore, by making the Fe-based alloy layer an alloy layer containing 0.1 to 5 at% of at least one element selected from B, C, and N, the resistance changes even in a lower applied magnetic field. Furthermore, by using the magnetoresistive film of the present invention in a magnetic circuit, a magnetoresistive element that operates with a low applied magnetic field can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a magnetic thin film according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional Fe/Cr multilayer film and a Fe/Cr multilayer film of the present invention.
Graph showing the magnitude of electrical resistance change due to external magnetic field of T a / T a C multilayer film, Figure 3 shows the Fe layer T of the present invention.
a Graph showing the magnitude of the maximum electrical resistance change depending on the number of Fe layers in a C multilayer film, FIG.
Figure 5 is a graph showing changes in the magnitude of the magnetoresistive effect when B, C, and N are added to the Fe layer of the Fe/TaC multilayer film of the present invention. B,
Graph showing changes in coercive force when C and N are added, No. 6
The figure is a perspective view showing the process of forming the magnetoresistive element of the present invention. Explanation of symbols

Claims (1)

[Claims] 1. In a magnetic thin film having a multilayer structure with an intermediate layer having a different composition interposed between the Fe layer and the intermediate layer having a different composition, the intermediate layer is paramagnetic and non-insulating, and the magnetization of the Fe layer in a demagnetized state is are antiparallel above and below the intermediate layer, and the number of the Fe layers is 4.
A magnetoresistive film characterized by having more than one layer. 2. In a magnetic thin film having a multilayer structure with an Fe-based alloy layer interposed through an intermediate layer of another composition, the intermediate layer is paramagnetic and non-insulating, and in a demagnetized state, at least one of the magnetizations of the Fe-based alloy layer is Some of the above Fe
A magnetoresistive film characterized in that the number of alloy layers is four or more. 3. The magnetoresistive film according to claim 2, wherein the Fe-based alloy layer contains 0.1 to 5 at% of at least one element selected from B, C, and N. Magnetoresistive film. 4. A magnetoresistive element using the magnetoresistive film according to claims 1 to 3 in at least a part of a magnetic circuit.