JPH02312287A - Magnetoresistance effect element - Google Patents

Abstract

PURPOSE:To enable a ferromagnetic magnetoresistance material layer to be given an enough bias by a method wherein the product of the saturation magnetization and the thickness of a soft magnetic bias auxiliary layer is specified to that of the ferromagnetic magnetoresistance effect material layer. CONSTITUTION:A ferromagnetic magnetoresistance effect MR material layer 1 contains Ni, Fe, and Co as main components, where the composition ratio of Ni ranges from 80% to 83% by weight and that of Co ranges from 6% to 9% by weight, and the product of the saturation magnetization and thickness of a soft magnetic bias auxiliary layer 3 is set to be 85-105% of that of the MR material layer 1. A magnetic field 8 induced inside the MR material layer 1 and a magnetic field 10 induced in the soft magnetic bias auxiliary layer 3 by currents 5 and 6 have the same direction, and a magnetic field 7 induced in the auxiliary layer 3 and a magnetic field 9 induced in the MR layer 1 are also in the same direction. At this point, in the region where the product ratio is above 105% or below 85%, a nonlinear distortion increases to more than 0.1 in absolute value. By this setup, the MR layer 1 can be given an optimal bias.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetoresistive element (hereinafter referred to as an MR element) used in a magnetic head, a magnetic sensor, and the like.

(Prior Art) MR elements using magnetoresistive effects have high reproduction sensitivity and are therefore widely used in magnetic heads, magnetic sensors, and the like. In principle, in an MR element, in order to obtain a linear response to a signal magnetic field, the angle between the sense current supplied to the magnetoresistive material layer (hereinafter referred to as MR material layer) and the magnetization of the MR material layer must be approximately 45 A bias means is required to set the value at the same time.

As a method of biasing the MR material layer, Utility Model Application No. 60-159
No. 518 discloses a structure in which a soft magnetic bias auxiliary layer and an MR material layer are laminated with a nonmagnetic conductor layer in between. In this configuration, the specific resistance of the soft magnetic bias auxiliary layer is M
Since the resistivity is significantly higher than that of the R material layer, most of the sense current flows through the MR material layer, magnetizing the soft bias auxiliary layer, and the magnetic field generated by the soft bias auxiliary layer causes the MR material layer to is biased.

Regarding this bias method, Japanese Patent Application Laid-Open No. 62゜234
No. 329 states that the product of the saturation magnetization and film thickness of the soft magnetic bias auxiliary layer is 60 times the product of the saturation magnetization and film thickness of the ferromagnetic MR element.
% or more and 90% or less, it is disclosed that a stable bias can be supplied.

Furthermore, regarding the MR material layer, Japanese Patent Application No. 63-17474
Publication No. 2 discloses that the main components are Ni, Fe, and Co, and N
By setting the composition ratio of i to 80% to 83% by weight and the composition ratio of Co to 6% to 9% by weight, M
It is disclosed that an MR material having a large R ratio and exhibiting good soft magnetic properties can be obtained.

Table 1 shows the configuration of a conventional magnetoresistive head.

As shown in Table 1, N15zFex is used as the MR material layer.
oCos, a Ti shunt film as the nonmagnetic conductor layer, and CoZrMo as the soft magnetic bias auxiliary layer, the MR material layer and the shunt layer were formed by vacuum evaporation, and the soft magnetic bias auxiliary layer was formed by high frequency sputtering. . M.R.
The shape of the element is 1100p long and 10pm wide.

Table 1 In the example shown in Table 1, the product of the thickness of the soft magnetic bias auxiliary layer and the saturation magnetization is 7 of the product of the thickness of the MR material layer and the saturation magnetization.
It is 5%.

A current of 20 mA was supplied to the created MR element, and the resistance change (hereinafter referred to as R-
H curve) was measured. The slope of the LH curve for an external magnetic field of -50e to 50e (A/10 in Figure 4, hereinafter referred to as
When the normalized sensitivity (referred to as normalized sensitivity) was calculated, 0.01210e was obtained. Also, the difference between the y-intercept of the straight line representing normalized sensitivity and the y-intercept of the external magnetic field R-Hll (B in Figure 4) and the difference in resistance change between external magnetic fields -50e and 50e (A in Figure 4) When the ratio B/A (hereinafter referred to as nonlinear distortion) was calculated, it was -0,
2 was obtained. The value of nonlinear distortion is −0,1 from the point of symmetry.
Although it is desired that the value be 0.1 or less, the value of nonlinear distortion in the above MR element exceeds this range. Such an increase in nonlinear strain is observed in the MR material NiFeC.

This shows that because the anisotropic magnetic field is large, a sufficient bias cannot be applied with the same bias magnetic field as the MR material layer with a small anisotropic magnetic field.

(Problem to be solved by the invention) NiszFetoCos alloy has an MR ratio of 5% and N
Since it is 2.5% larger than iFe, it is considered to be suitable as an Mρ layer material, but because the anisotropic magnetic field is large, sufficient bias can be obtained with the conventional value of the product of film thickness and saturation magnetic field. I can't.

An object of the present invention is to provide an MR element that can sufficiently bias an MR material layer having a large anisotropic magnetic field.

(Means for Solving the Problems) According to the present invention, in a magnetoresistive element having a structure in which a ferromagnetic magnetoresistive material layer and a soft magnetic bias auxiliary layer are laminated with a nonmagnetic conductor layer in between, The ferromagnetic magnetoresistive material layer is made of Ni, Fe, or C.

is the main component, the Ni composition ratio is 80% by weight or more and 83% by weight or less, the Co composition ratio is 6% by weight or more and 9% by weight or less, and the product of the saturation magnetization and the film thickness of the soft magnetic bias auxiliary layer is It is possible to obtain a magnetoresistive element characterized in that the product of the saturation magnetization and the film thickness of the ferromagnetic magnetoresistive material layer is 85% or more and 105% or less.

(Operation) FIG. 1 is a perspective view of an MR element for explaining the present invention in detail.

As shown in FIG. 1, it has a structure in which an MR material layer 1 made of NiFeCo, a shunt layer 2 made of a nonmagnetic layer, and a soft magnetic bias auxiliary layer 3 are laminated in this order.

FIG. 2 shows M in FIG. 1 for explaining the operating principle of the present invention.
FIG. 3 is a cross-sectional view of an R element.

As shown in FIG. 2, when currents 4, 5, and 6 flow through the MR material layer 1, shunt layer 2, and soft magnetic bias auxiliary layer 3, the currents 4 and 5 cause the reefing bias auxiliary layer 3 to MR material layer 1 receives magnetic field 8 due to currents 5 and 6, MR material layer 1 generates magnetic field 9, and soft magnetic bias auxiliary layer 3 generates magnetic field IO.

In FIG. 2, the magnetic field 8 due to the current 5.6 in the MR material layer 1 and the magnetic field 10 generated by the soft magnetic bias auxiliary layer 3 are in the same direction, and further due to the current 4.5 in the soft magnetic bias auxiliary layer 3. The magnetic field 7 and the magnetic field e generated by the MR material layer are also in the same direction. Therefore, the MR material layer 1 and the soft magnetic bias auxiliary layer 3 can strengthen their magnetization with each other by the magnetic field generated by the current, and can provide a magnetization bias to the MR material layer 1.

Here, the magnetic field generated by the soft magnetic bias auxiliary layer 3 is a function of the thickness and saturation magnetization of the soft magnetic bias auxiliary layer 3,
The larger the film thickness and the saturation magnetization value, the stronger the bias magnetic field can be generated for the MR material layer 1. However, when a magnetic field strong enough to saturate the MR material layer 1 is applied, the sensitivity of the MR material layer 1 to the external magnetic field decreases.
Moreover, non-linear distortion increases, which is not preferable.

FIG. 3 shows the soft magnetic field versus the product of the film thickness and saturation magnetization of the MR material layer 1 when the anisotropic magnetic field of the M-effect material layer is 90e and a current sufficient to saturate the soft magnetic bias auxiliary layer 3 is supplied. The ratio of the product of the film thickness and saturation magnetization of the magnetic bias auxiliary layer 3 is MR
These are the results obtained by one-dimensional self-consistent calculation of the normalized sensitivity of the material layer to an external magnetic field and its influence on nonlinear strain.

As shown in FIG. 3, in the region where the product of the film thickness and saturation magnetization of the soft magnetic bias auxiliary layer 3 is 85% or less and 105% or more of the product of the film thickness and saturation magnetization of the MR material layer 1, the nonlinear The distortion increases and its absolute value exceeds 0.1. If the nonlinear strain increases, it becomes impossible to read correct information from the reproduced waveform of the MR head. It is necessary to set the value to 85% or more and 105% or less.

Furthermore, the product of the film thickness and saturation magnetization of the soft magnetic bias auxiliary layer 3 is 90% or more of the product of the film thickness and saturation magnetization of the M-effect auxiliary layer 1.
In the region of 00% or less, the change in the value of nonlinear distortion is small, so results with good reproducibility can be obtained.

Furthermore, in order to ensure a sufficient S/N ratio against noise as an MR element, a reproduction output of approximately 300 μV is required. Maximum resistance change 5% specific resistance 20vΩcm, radiation 10μ
When a sense current of 20 mA is supplied using an MR material layer with a length of 100 μm and a magnetic field change of 10 e, a
To obtain oopv, the normalized sensitivity is 0.011.
0e or more is required. In FIG. 3, the normalized sensitivity is 0.0110e in the region where the product of the film thickness and saturation magnetization of the soft magnetic bias auxiliary layer 3 is 105% or less to maintain 60% of the product of the film thickness and saturation magnetization of the MR material layer. The above is obtained.

Therefore, in order to provide an optimal bias to the MR material layer 1 whose film thickness and saturation magnetization are known, it is necessary to consider both sensitivity and nonlinear strain, and to adjust the film thickness and saturation magnetization of the laminated soft magnetic bias auxiliary layer. The product may be set to 85% or more and 105% or less of the product of the film thickness of the M magnet layer and the saturation magnetization.

Furthermore, in consideration of reproducibility, the product of the thickness and saturation magnetization of the soft magnetic bias auxiliary layer may be set to 90% or more and 100% or less of the product of the thickness and saturation magnetization of the MR material layer.

(Example) Table 2 shows the configuration of the first embodiment of the present invention.

The first embodiment uses Ni5 as the MR material layer in FIG.
2FexoCoa, a Ti shunt film as the nonmagnetic conductor layer, and CoZrMo as the soft magnetic bias auxiliary layer.
The MR material layer and the shunt layer are formed by vacuum evaporation method,
The soft magnetic bias auxiliary layer was formed by high frequency sputtering. The shape of the MR element is 1100p in length and 10pm in width.

Table 2 In this example, the product of the thickness and saturation magnetization of the soft magnetic bias auxiliary layer is 94
%.

Supplying a current of 20 mA to the created magnetoresistive head,
The normalized sensitivity to external magnetic field was measured and was 0.01.
510e was obtained. Moreover, the nonlinear magnetostriction was −0.08, which was a good value.

Table 3 shows the configuration of the second embodiment of the present invention.

The second embodiment uses Ni as the MR material layer in FIG.
Using 82Fe12Co6, a Ti shunt film as the nonmagnetic conductor layer, and CoZrMo as the soft magnetic bias auxiliary layer, the MR material layer and the shunt layer were formed by vacuum evaporation, and the soft magnetic bias auxiliary layer was formed by high frequency sputtering. . The shape of the MR element is 100 μm in length and 10 pm in width.

Table 3 In this example, the product of the thickness and saturation magnetization of the soft magnetic bias auxiliary layer is 88 of the product of the thickness and saturation magnetization of the MR material layer.
%.

Supplying a current of 20 mA to the created magnetoresistive head,
The normalized sensitivity to external magnetic field was measured and was 0.01.
610e was obtained. Moreover, the nonlinear magnetostriction was −0.1, which was a good value.

Table 4 shows the configuration of the third embodiment of the present invention.

The third embodiment uses N1 as the MR material layer in FIG.
5oFeuCo9, Ti shunt film as the nonmagnetic conductor layer, CoZrMo as the soft magnetic bias auxiliary layer,
The MR material layer and the shunt layer are formed by vacuum evaporation method,
The soft magnetic bias auxiliary layer was formed by high frequency sputtering. The shape of the MR element is 1100p in length and 10 μm in width.

(Margin below) Table 4 In this example, the product of the thickness and saturation magnetization of the soft magnetic bias auxiliary layer is 10 of the product of the thickness and saturation magnetization of the MR material layer.
It is 3%.

When a current of 2eOmA was supplied to the created magnetoresistive head and the normalized sensitivity to external magnetic field was measured, it was 0.0.
1610e was obtained. Moreover, the nonlinear magnetostriction was 0.01, which was a good value.

(Effects of the Invention) As described above, in the magnetoresistive element according to the present invention, the product of the thickness of the soft magnetic bias auxiliary layer and the saturation magnetization is
High sensitivity and low distortion characteristics can be obtained by setting the product of the material layer thickness and saturation magnetization to 85% or more and 105% or less. It is possible to create high-power, low-noise devices.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the magnetoresistive element for explaining the present invention in detail, and FIG. 2 is a cross-sectional view of the magnetoresistive element shown in FIG. 1 for explaining the operating principle of the present invention. Figure 3 shows the ratio of the product of the film thickness and saturation magnetization of the soft magnetic bias auxiliary layer 3 to the product of the film thickness and saturation magnetization of the MR old layer 1 of the MR element shown in Figure 1, normalized sensitivity, and nonlinearity. FIG. 3 is a characteristic diagram showing the correlation with distortion. FIG. 4 is a diagram showing the relationship between the external magnetic field and the resistance change normalized by the maximum resistance change of a conventional MR element.

In the figure, 1... MR material layer, 2... shunt film, 3... soft magnetic bias auxiliary layer, 4.5.6... current, 7.8...
...Magnetic field due to current, 9...Magnetic field generated by the MR material layer, 10...Magnetic field generated by the soft magnetic bias auxiliary layer.

Fig. 1 Fig. 2 Fig. 4, 5.6 Current Otsu 8 Magnetic field due to current 9 Magnetic field generated by the MR material layer 10 Magnetic field generated by the soft magnetic bias auxiliary layer Fig. 3 0.5 1.0 Thickness of MFI material layer x Saturation magnetization Figure 4 ■

Claims (2)

[Claims] (1) In a magnetoresistive element having a structure in which a ferromagnetic magnetoresistive material layer and a soft magnetic bias auxiliary layer are laminated with a nonmagnetic conductor layer in between, the ferromagnetic magnetoresistive material layer is made of Ni, Fe, The main component is Co, and the composition ratio of Ni is 8.
0% by weight or more and 83% by weight or less, Co composition ratio is 6% by weight
9% by weight or less, and the product of the saturation magnetization and film thickness of the soft magnetic bias auxiliary layer is 85% or more and 105% or less of the product of the saturation magnetization and film thickness of the ferromagnetic magnetoresistive material layer. Characteristic magnetoresistive element. (2) The product of the saturation magnetization and film thickness of the soft magnetic bias auxiliary layer is 9 of the product of the saturation magnetization and film thickness of the ferromagnetic magnetoresistive material layer.
The magnetoresistive element according to claim (1), wherein the magnetoresistive effect element is 0% or more and 100% or less.