JPS6064484A - Ferromagnetic magnetoresistance effect alloy film - Google Patents

Abstract

PURPOSE:To contrive increase of the ferromagnetic magnetoresistance effect, decrease of the saturation magnetic flux density and upgrade of the uniaxial magnetic anisotropy by a method wherein the composition of an Ni-Fe-Co system alloy is chosen in a limited extent. CONSTITUTION:The weight composition of a ferromagnetic magnetoresistnace efect alloy film consisting of an Ni-Fe-Co ternary alloy is chosen in the extent indicated by oblique lines in the diagram. The alloy film, whose composition has been chosen in hte extent, has characteristics of having a larger ferromagnetic magnetoresistance effect, showing a uniaxial anisotropy and having a larger saturation magnetic flux density, in a thin film strip form. This alloy film is suitable to utilize for magnetic sensors, magnetoresistance effect type thin film magnetic heads, magnetic valve detecting elements, etc.

Description

Detailed Description of the Invention (Field of Application) The present invention relates to a ferromagnetic magnetoresistive alloy film, and is particularly applicable to a thin film strip shape used in magnetic sensor elements, magnetic head elements 2, magnetic bubble detection elements, etc. The present invention relates to a ferromagnetic magnetoresistive alloy film that is used for. More specifically, the present invention relates to a ferromagnetic magnetoresistive alloy film having high magnetic field sensitivity in the form of a thin film strip.
.

(Background) In recent years, ferromagnetic magnetoresistive alloy films have been used to detect magnetic sensors and magnetoresistive thin-film magnetic henodes that detect the rotation angle and rotational speed of an object, as well as the ferromagnetic magnetoresistive alloy films. Figure 1 shows the schematic structure of a magnetic sensor that detects the rotation angle and rotation speed.

The rotation axis of the rotating body (not shown) that is the subject, that is,
A detection unit 22 having a magnetic recording medium 20 on its side is fixed to the shaft 21 . The magnetic recording medium 20 is attached 25 in the circumferential direction at a predetermined recording wavelength by a magnetic head (not shown).

On the other hand, a substrate 30 is disposed adjacent to the surface of the magnetic recording medium 20, and a strip-shaped ferromagnetic magnetoresistive alloy film 1 is deposited on the surface thereof facing the magnetic recording medium 20. , sputtering, or other methods.

Since the ferromagnetic magnetoresistive alloy film l formed on the substrate 30 receives the magnetic field from the magnetized pattern of the magnetic recording medium 200, the electrical resistance changes as the shaft 210 rotates. Based on this, the rotation angle and rotation speed of the rotating body can be detected by performing a well-known trick.

FIG. 2 is a schematic perspective view showing an example of a magnetoresistive thin film magnetic head.

A permanent magnet film 31 for applying a bias magnetic field is formed on a substrate 30, and a strip-shaped ferromagnetic magnetoresistive alloy film l is formed on the upper surface of the permanent magnet film 31 with a nonmagnetic insulating film 32 interposed therebetween. Lead wires 33 are connected to both ends of the resistance effect alloy film l.

In FIG. 2, due to the influence of the magnetic field 2 generated from the recording medium (not shown), the electric resistance of the ferromagnetic rod (resistance effect alloy film 1 changes by 1 J). Therefore, the current flowing through the alloy film 1 or Information can be generated based on the potential difference between G-1933 and G-33.

In this case, the permanent magnet film 31 is magnetized 4o in the same direction as the magnetic field 2 generated from the +IC recording medium, and functions to apply a ferromagnetoresistive alloy film IK bias magnetic field.

As the ferromagnetic magnetoresistive alloy film of the element using the ferromagnetic magnetoresistive effect as described above, 82-layer fIcX
Ni-18wt%Fe alloy? @ Ruber −q.

A has been widely used in the past, and has a film thickness of 25 to 400 mm in magnetic sensors, magnetoresistive thin film magnetic heads, magnetic bubble detection elements, etc.
Generally, a strip-shaped ferromagnetic magnetoresistive film having a width of about 20 to 30 μm is used.

The ferromagnetic magnetoresistive effect Nor 1 of a permalloy film with a film thickness of 30 to 40 nm is approximately 2.5X, and the permalloy film with a film thickness of 30 to 40 nm
The Nor 1 of a 0-400 nm permalloy film is about 3.5X.

r IE) J Transaction@on Mag
nesias J (MAG-11+m4, 1975
July issue No. 1018-1038) K is an alloy material with a larger ferromagnetic magnetoresistance effect than permalloy film.
2XNi-8%Fe, (70~90)XNi-(
30-10) XCo, 67XN+ -30XC.

It is described that there is 3XCr.

r Th1n Soi! id Films J (48
Vol., 1978, fJs247-255 members) contains the ternary alloy 72JiiXNi-18 heavy 1itX Fe-
101ift%Co, 64 MllN Ni-1'
7 *Product X Fe-19]i 3n%Co and 60
%Ni-11 weight% Fe-29%Co by weight is disclosed, and it is stated that these have a greater ferromagnetic magnetoresistive effect than permalloy films.

Furthermore, r IEFiB Transactions o
n MagneticsJ CMAG-19, m2,
65XN (March 1983 issue No. 104-110)
i -15%P'e-20X Co and 6゜XNi
-10XFe-30XCo is disclosed, and it is stated that these ternary alloys also have a greater ferromagnetic magnetoresistive effect than permalloy films.

The positions of these known magnetic alloy films, which have a greater arsenic sulfur resistance effect than the Malloy film, in the Ni-Fe-Co ternary diagram are indicated by circles in Figure 5. There is.

However, these magnetic ternary alloy films have the following drawbacks.

In general, the magnetoresistive alloy films of magnetic sensor elements and magnetoresistive thin film magnetic head elements are shown in FIGS. 1 and 2.
As can be easily understood from the figures and the description thereof, it is used in the form of a thin film strip. At this time, as shown in FIG. 2, the magnetic field 2 is applied within the thin M plane in its width direction, that is, at right angles to its length direction. .

Figure 1s3 is a perspective view schematically showing this state. In this case, the dimensions of the rear section are typically 20 to 20 mm.
50 nm, width W 5-40 pm, length L 100-30
00 μm. That is, in this magnetoresistive alloy thin film, the length L is sufficiently larger than its width W, and the width W is sufficiently larger than its film thickness.

By the way, the magnetoresistive alloy films shown in FIGS. 1 to 3 require not only a large ferromagnetic magnetoresistive effect, but also the following two points.

First, it must have good magnetic field sensitivity - that is, it must exhibit a sufficient ferromagnetic magnetoresistive effect even if the applied magnetic field 2 is small.

The second requirement is that the hysteresis phenomenon with respect to the magnetic field 2 is small; that is, the magnetic film must have uniaxial magnetic anisotropy, with the direction of length L being the axis of easy magnetization.

Regarding the first magnetic field sensitivity, it is generally considered that it is best to use the apparent anisotropic magnetic field 11k as a parameter representing the udi field sensitivity, which will be further explained.

The apparent anisotropic magnetic field H' is as shown in FIG. 4 when a magnetic field 2 #J is applied in the width direction of the thin strip-shaped magnetoresistive alloy film l shown in FIG. This is a magnetic field at which the magnetoresistive effect can be considered to have been practically saturated (even if the I:11 magnetic field H changes, the resistance value R no longer changes).

Magnetoresistive Film The magnetoresistive alloy film of the magnetic head is normally used by applying a bias magnetic field in a direction forming an angle of about 45 degrees with respect to the direction of length L. In this case, as for the magnetic field sensitivity of a single magnetoresistive alloy film, it is common to evaluate the characteristics of the magnetic film using the above-mentioned apparent anisotropic magnetic field H'.

Even in the magnetic bubble detection element, r IEEE Trans
actions on MagnetieJ (MAG
-19, N12 +March 1983 No. 104-1
As described on page 1G, the apparent anisotropic magnetic field H
' to evaluate its characteristics.

The apparent anisotropic magnetic field H' of the magnetoresistive alloy film in the shape shown in FIG. 3 is given by the following equation (1).

In equation (1), Hk is the true anisotropic magnetic field, Bs is the saturation magnetic flux density, and a and b are constants that are not related to the characteristics of the magnetic film. Therefore, in the formula III, those related to the magnetic film itself are the true anisotropic magnetic field Hk and the saturation magnetic flux density Bs.

By the way, a magnetic film with good magnetic field sensitivity has a small apparent anisotropic magnetic field 1 ('k).
As is clear, 2t referring to equation (1) means that the true anisotropic magnetic field HK is small and the saturation magnetic flux density Bs is small.

Ni-Fe made of known materials disclosed in the above publications
-Co all-gold films both have a large saturation magnetic flux density tiBs, and therefore have the disadvantage that the apparent anisotropic magnetic field H'k is large.

Furthermore, 2%Ni-8XFe, (70~90)XNi
-(30-10)XCo and 67%Ni-30%・-
3X Cr and the like have fewer drawbacks in that it is difficult to obtain Plk with uniaxial magnetic anisotropy.

(Objective of the Invention) The present invention has been made to eliminate the above-mentioned drawbacks, and its purpose is to remove the permalloy film, which is an 82wtXNi-18wtXFe alloy, or a known Ni-Fe-Co ternary alloy. Compared to the film, in the thin film strip shape, the ferromagnetic magnetoresistive effect is large, the saturation magnetic flux density Bs is smaller than that of known materials (i.e., the apparent anisotropy field is smaller), and the −axial magnetic anisotropy is smaller than that of known materials. An object of the present invention is to provide a ferromagnetic magnetoresistive alloy film exhibiting good properties.

(Summary of the invention 4I) - The present invention provides a Ni-Fe-Co ternary alloy film that includes:
When its weight composition is expressed as Nl + - ry Fe yo - Coy, the following inequality % formula % is set to a composition range that satisfies the above x and y, so that the ferromagnetic magnetoresistive effect is better than that of permalloy film. N1-Fe-C is known to have a large saturation magnetic flux density.

It is smaller than a ternary alloy film and exhibits −axial magnetic anisotropy.
The feature is that it is possible to realize a good thin film strip-like ferromagnetic magnetoresistive alloy film.

(Embodiments of the Invention) The present inventors have developed a Ni-Fe-Co ternary alloy to obtain an IJ tube-shaped ferromagnetic magnetoresistive alloy film. In order to determine the composition range, the ternary alloy films having various compositions were experimentally created. l Then, for each of these, the ferromagnetic magnetoresistive effect Δl (%), the saturation magnetic flux density T (relative value when Permalloy is set to 1), 2, and whether or not they exhibit uniaxial magnetic anisotropy are measured. did. The results are shown in Table 1 (Mueya Sen).7 In these experiments, the Ni-Fa-Co alloy film corresponding to each sample was produced from a single evaporation source with a predetermined composition. It is obtained by vapor deposition. Resistance heating was used as the heating source for the fish scraps, but the results would be exactly the same even if electron beam heating was used.

Also, the vacuum pressure during vapor deposition was 5 x 10' Torr.
The following is required, and in order to obtain a ferromagnet with less variation and a large ferromagnetic magnetoresistance effect, l x 10-'
It was found that it is desirable to have a pressure of less than Torr.

The temperature of the substrate during vapor deposition is generally kept within the range of 200 to 400°C, and the temperature is approximately 350°C in order to obtain an alloy film with less scattering and a large ferromagnetic magnetoresistive effect.
℃ was found to be desirable.

In this case, the substrate can be made of glass, ceramics, etc., which have a sufficiently flat ttit.The deposition rate may be in the range of 1 to 3 nm/8, and the degree of deposition iA depends on the ferromagnetic magnetoresistive effect. It was confirmed that there would be no major impact.

Methods for imparting uniaxial magnetic anisotropy include evaporation in a DC or AC magnetic field in a fixed direction, oblique evaporation in which the evaporated particles are tilted away from the normal direction of the substrate surface, and oblique evaporation and rotation of the substrate. Alternatively, a method of vapor deposition in a rotating magnetic field, etc. can be used.

The simplest method for imparting uniaxial magnetic anisotropy is to deposit in a direct current magnetic field.7 The film thickness varies depending on the application, but is between 20 and 400 nm.
It is easy to vary within the range of m.

Table 1 shows the film thickness of 45 to 50'nm formed by vapor deposition method.
-x in Ni-F'e-Co ternary alloys of various compositions
The ferromagnetic magnetoresistive effect, saturation magnetic flux density, and uniaxial magnetic anisotropy of yxy were measured.

N'1. -y k'e at Lo y It is generally known that increasing the Co content in alloy films increases the ferromagnetic magnetoresistance effect, but from the experimental results in Table 1, it is clear that It can be seen that in order to exhibit a larger ferromagnetic magnetoresistance effect than the permalloy film, it is necessary to increase the composition ratio of co to 15% by weight or more.

That is, the yFi needs to be 0.15 or more. In the N1-Fe-Co ternary component diagram shown in FIG. 5, this is the shaded area on the Co side of the straight line 11 in the figure.

Next, also from Table 1, NiFe-C.

It can be seen that in 1272y alloy M, in order to obtain a -axis magnetically anisotropic film, it is necessary to make the Fe composition ratio 5% by weight or more. That is, it is necessary that X be 0.05 or more, and this is the shaded region of Fe@ rather than the direct $12 in FIG.

In addition, in the Ni-Fe-Co alloy film, the front r-
x-yxy The composition range in which the saturation magnetic flux density is small compared to the known Ni-Fe-Co alloy film is that y is 0.15 or more, and
It can be determined from Table 1 that y is in the range of (0.5-2.5 g) or less in the composition range that satisfies the condition 52 that y is 0.05 or more. This area is 1. : This is the shaded area on the Ni side of the straight line 13 in Figure 55.

Taking all the above into account, it is clear that the ferromagnetic magnetoresistive effect characteristics suitable for the purpose of the present invention - in other words, (1) the ferromagnetic magnetoresistive effect is larger than that of the permalloy film, and (2) - the axial magnetic Group 1 of Ni-Fe-Co base metal films exhibiting anisotropy and (3) a higher saturation magnetic flux density than known Ni-Fe-Co alloy films.
-x-yzy composition range is three straight lines 11°12.1 in Figure 5.
It will rain in the area surrounded by 3.

Furthermore, according to the experiments of the present inventors, NiO, 71"-FeO, 09-COO,
It was confirmed that the ferromagnetic magnetoresistive effect of the sample No. 20 with a film thickness of 350 nm was 48%, which was larger than the ferromagnetic magnetoresistive effect of Permalloy of the same thickness, which was 3.5X.

Note that the method for forming the alloy film of the present invention is not limited to the vacuum vaporization method, and it goes without saying that a sputtering method is also effective.

(Effects of the Invention) From the above description, it is clear that the strong fIi magnetoresistive alloy film in the composition range limited by the present invention, as shown in ρ.
In the thin film strip shape that is usually used in practical use,
Compared to similar alloys known as Vermaloya, which have traditionally been used for the same purpose, the ferromagnetic magnetoresistance effect is large, the saturation magnetic flux density is so small that it does not pose a practical problem, and it has -axial magnetic anisotropy. This effect makes it extremely suitable for use in magnetic sensors, magnetoresistive thin film magnetic heads, magnetic bubble detection elements, and the like.

The Ni-Fe-Co alloy of the present invention also has the advantage that its constituent elements are Ni, Fs, and Co, which are nine elements with relatively high vapor pressure and can be obtained industrially with good reproducibility. I also have

[Brief explanation of the drawing]

Figure 1 shows the schematic structure of a resistive thin film magnetic sensor for providing rotation angle and rotation speed) night time, 2nd f! Ati
A perspective view showing the schematic structure of a magnetoresistive thin film rut head; Fig. 3 is a perspective view illustrating the current direction and magnetic field application direction when using a ferromagnetic magnetoresistive film in the IJ knob shape; Figure 4 shows the relationship between the change in resistance and the magnetic field when a magnetic field is applied to a ferromagnetic magnetoresistive film, and Figure 5 shows the Ni-Fe-Co ternary component diagram and the limited composition of the present invention. It is a figure explaining a range. l...Ferromagnetic magnetoresistive alloy film, 2...Magnetic field applied Patent attorney Michihito Hiraki Figure 1 2n Figure 2 Figure 3 Hi

Claims (3)

[Claims] (1) In a ferromagnetic magnetoresistive alloy film made of a Ni-Fe-Co ternary alloy, its weight composition is N11-
When expressed as ry-Fe-Co, the composition range satisfies the following two conditions: x y X is 0.05≦X, and y is 0.15≦y≦0.5-2.5 z Characteristic ferromagnetic magnetoresistive alloy film. (2) The ferromagnetic magnetoresistive alloy film has a shape that is
A ferromagnetic magnetoresistive alloy film as described in the patent, characterized in that it is in the form of a thin film stop whose length is sufficiently longer than its width. (3) The ferromagnetic magnetoresistive alloy film according to claim 1 or 2, characterized in that the film thickness is 20 to 400 nm.