JP3028585B2 - Magnetoresistive element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetoresistive effect element (hereinafter abbreviated as MR element) that detects a magnetic field using a strong magneto-resistance effect (hereinafter abbreviated as MR effect). ).

[Conventional technology]

2. Description of the Related Art MR elements that detect a magnetic field using the MR effect are currently being actively used as magnetic sensors, magnetic heads, rotation detection elements, position detection elements, and the like. In general, NiFe, which is listed as an MR element material, has a small anisotropic magnetic field of about 40e and exhibits very good soft magnetic characteristics, and is therefore suitable for a material for a high-sensitivity MR element such as an MR head for magnetic recording. Have been.
However, for higher sensitivity and higher output,
Materials with higher MR ratios are needed. MR than NiFe
Although a material having a large ratio is NiCo, the value of the anisotropic magnetic field is large and is not suitable for a high-sensitivity MR element. In consideration of the above points, the NiFeCo ternary alloy film proposed by us (described in Japanese Patent Application No. 63-174742) has an anisotropic magnetic field value of Ni.
Although the value is about the same as that of Fe, the value of MR ratio is on the order of 5%, which is close to that of NiCo, and is promising as a high-sensitivity MR element material.

[Problems to be solved by the invention]

An important characteristic of the MR element material is a response of the electric resistance R to the applied magnetic field H (hereinafter referred to as RH characteristic). The MR element made of the above-mentioned NiFe film or NiFeCo film is manufactured, and the R-H When the characteristics were examined, in some of the devices, hysteresis and jumps (called Barkhausen jumps) of the RH curve were observed. Here, the cause of these noises will be considered. NiFe film or Ni
Uniaxial magnetic anisotropy is induced in the FeCo film by film formation in a magnetic field. However, when uneven internal stress is distributed in the film, the magnetic anisotropy is likely to be dispersed due to the inverse magnetostriction effect. The inverse magnetostrictive energy E representing the magnitude of the inverse magnetostrictive effect is represented by the following equation, and is proportional to the product of the internal stress σ and the saturation magnetostriction constant λs.

E = −1.5 · λs · σ Therefore, in a film having a large E value and a remarkable magnetic anisotropy dispersion, the magnetization rotation is disturbed with a change in the applied magnetic field, and hysteresis and Barkhausen A jump will occur.

From the above considerations, it is important to form a film having a sufficiently small reverse magnetostriction effect in order to essentially solve the problem, in order to realize an MR element having a good magnetic sensing ability without noise.

[Means for solving the problem]

The present invention provides a magnetoresistive element having a magnetoresistive layer provided on one side of a substrate, wherein the magnetoresistive layer is a Ni-Fe-Co alloy film, and the absolute value of the inverse magnetostrictive energy of the magnetoresistive layer is The value is set to be equal to or less than the uniaxial magnetic anisotropic energy value.

Further, in the present invention described above, the magnetoresistance effect layer is made of Ni.
_It is preferably an ₈₂ Fe ₁₂ Co ₆ alloy film.

Further, in the present invention described above, the magnetoresistance effect layer is made of Ni.
_The uniaxial magnetic anisotropy energy value of the ₈₂ Fe ₁₂ Co ₆ alloy film is u
= H _K · M _S / 2, and its u value is preferably around 340 J / m ³ .

Wherein, u is a uniaxial magnetic anisotropy energy value induced during deposition of the magnetoresistive layer, H _K is the anisotropy field, M _S is the saturation magnetization.

Furthermore, in the present invention described above, the Ni ₈₂ Fe ₁₈ alloy film of the magnetoresistive layer is preferably used.

Further, in the present invention described above, the magnetoresistance effect layer is made of Ni.
The u value of the uniaxial magnetic anisotropy energy value of the ₈₂ Fe ₁₈ alloy film is
It is preferable to be around 140 J / m ³ .

[Action]

According to the present invention, there is provided a magnetoresistance effect element characterized in that the absolute value of the inverse magnetostriction energy in the magnetoresistance effect layer is equal to or less than the uniaxial magnetic anisotropy energy value.

That is, according to the present invention, the film formation conditions are selected so that the absolute value of the reverse magnetostriction energy of the magnetoresistive layer is equal to or less than the uniaxial magnetic anisotropic energy value induced during the film formation. Since the obtained uniaxial magnetic anisotropy is not significantly affected by the inverse magnetostriction effect and hardly disperses, the magnetization is rotated uniformly with respect to an external magnetic field, and a good RH without hysteresis or Barkhausen jump is obtained. Characteristics are obtained.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of an MR element according to the present invention. In FIG. 1, a Ni ₈₂ Fe ₁₈ film having a film thickness of 40 to 150 nm to be the MR effect layer 2 was formed on a glass substrate 1 by an evaporation method. Deposition substrate temperature is 40 ~ 400 ℃, deposition rate is 0.1 ~ 1.
By making each film under various film formation conditions at 9 nm / s, the value of internal stress is changed, and a wide range (50-800 J /
A sample having an inverse magnetostriction energy of m ³ ) was prepared. During deposition, a magnetic field of 50 ° was applied by a Helmholtz coil to impart uniaxial magnetic anisotropy to the film. Next, the Au layer 3 was vapor-deposited by the same vapor deposition method (film thickness: 240 nm). Further, a predetermined photoresist pattern is formed on this laminate, and Ar
Perform ion etching in a gas atmosphere, length 2000μ
m, a rectangular shape having a width of 50 μm, and a terminal-shaped pattern. The etching conditions at this time were as follows: acceleration voltage: 500 V, A
r Gas pressure was 1 × 10 ⁻⁴ Torr. Further, a rectangular pattern 4 and a Au terminal 5 which are magnetically sensitive portions are formed by a photoresist process and selective chemical etching,
An element was manufactured.

The internal stress σ and the saturation magnetostriction constant λs of these films were measured, and the absolute value | E | of the inverse magnetostriction energy was calculated by the following equation: | E | = | 1.5 · λs · σ |
FIG. 2 shows the relationship between | E | found for each sample and the quality of the RH characteristics. Here, D, which is the quantity on the vertical axis, is
It is defined as the ratio d / h between the maximum value d of the difference in electrical resistance and the height h of the RH curve at the same magnetic field value (see FIG. 4). If no hysteresis or Barkhausen jump occurs in the RH curve, D = 0.

As is clear from FIG. 2, the reverse magnetostriction energy is 120 to 1
It can be seen that in the sample of 30 J / m ³ or less, good RH characteristics without hysteresis and Barkhausen jump can be obtained. This critical value is defined as the uniaxial magnetic anisotropy energy u = H _K · M _S / 2 = 14 induced at the time of film formation in the NiFe film.
Approximately equal to 0 J / m ^3. Here, H _K is the anisotropy field, M _S is the saturation magnetization.

Therefore, by using a NiFe film having an absolute value of the inverse magnetostriction energy equal to or less than the uniaxial magnetic anisotropy energy value as the magnetoresistive layer, a magnetoresistive element having a good magnetic sensing ability without noise is realized. .

Next, another embodiment of the MR element according to the present invention will be described. In FIG. 1, as the MR effect layer 2, Ni ₈₂ Fe ₁₂ Co ₆
A sample was produced in exactly the same configuration as in the above-described embodiment except that a film was used. The deposition substrate temperature is 40 to 400 ° C., the deposition rate is 0.3 to 1.1 nm / s, and the internal stress value is varied over a wide range (30
A sample having a reverse magnetostriction energy of 0 to 800 J / m ³ ) was prepared. FIG. 3 shows the relationship between the absolute value | E | of the inverse magnetostriction energy obtained for each sample and the amount D for determining the quality of the RH characteristic. In samples having | E | of 300 to 330 J / m ³ or less, good RH characteristics without hysteresis and Barkhausen jump are obtained. The critical value is NiFeCo
In the film, the uniaxial magnetic anisotropy energy induced at the time of film formation is substantially equal to u = H _K · M _S / 2 = 340 J / m ³ .

Therefore, by using a NiFeCo film whose absolute value of the inverse magnetostriction energy is equal to or less than the uniaxial magnetic anisotropy energy value as the magnetoresistive effect layer, a magnetoresistive effect element having a good magneto-sensitive ability without noise is realized. .

〔The invention's effect〕

As described above, according to the present invention, as the magnetoresistive layer, the inverse magnetostrictive energy is induced at the time of film formation.
By using a ferromagnetic material having an axial magnetic anisotropy energy or less, a magnetoresistive element having a good magnetic sensitivity without noise can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an MR element according to the present invention. FIGS. 2 and 3 are diagrams showing a relationship between an amount D representing the quality of an RH curve and an absolute value of inverse magnetostriction energy. FIG. 4 is a diagram showing the definition of a quantity D representing the quality of an RH curve. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... MR effect layer 3 ... Au layer 4 ... Rectangular pattern which is a magnetic sensing part 5 ... Au terminal

Claims (5)

(57) [Claims] 1. A magnetoresistive element having a magnetoresistive layer provided on one side of a substrate, wherein the magnetoresistive layer is a Ni—Fe—Co alloy film, and the reverse magnetostrictive energy of the magnetoresistive layer is A magnetoresistive element whose absolute value is equal to or less than a uniaxial magnetic anisotropic energy value. 2. The magnetoresistive element according to claim 1, wherein the magnetoresistive layer is a Ni ₈₂ Fe ₁₂ Co ₆ alloy film. 3. In the equation, u = H _K · M _S / 2, where u is a uniaxial magnetic anisotropic energy value induced at the time of forming the magnetoresistive layer, and H _K is an anisotropic magnetic field. in, M _S is the saturation magnetization, in u values represented the magnetoresistive element according to claim 1 or 2, characterized in that it is 340J / m ³ neighborhood. 4. A magnetoresistive element provided with a magnetoresistive layer on one side of a substrate, wherein the magnetoresistive layer is a Ni ₈₂ Fe ₁₈ alloy film, and the absolute value of the reverse magnetostrictive energy of the magnetoresistive layer is Is less than the uniaxial magnetic anisotropic energy value. 5. In the equation, u = H _K · M _S / 2, where u is a uniaxial magnetic anisotropic energy value induced at the time of forming a magnetoresistive layer, and H _K is an anisotropic magnetic field. in, M _S is the saturation magnetization, in u values represented the magnetoresistive element according to claim 4, characterized in that a 140 J / m ³ neighborhood.