JPH08279116A - Film of gigantic magnetoresistive material and method for adjustive magnetization of magnetoresistive material film - Google Patents

Abstract

PURPOSE: To decrease the leaking magnetic fields of a hard magnetic material film by freshly disposing a ferromagnetic layer between the hard magnetic material film and a nonmagnetic film. CONSTITUTION: This megalomagnetic reluctance material film is formed by successively laminating the hard magnetic material film 21, the newly formed ferromagnetic material film 22, the nonmagnetic film 23 and a soft magnetic material film 24 on a substrate 20 consisting of a nonmagnetic material. The nonmagnetic film 23 is formed of Cr, Au, Ag, Cu, etc., to a thickness of, for example, 20 to 40 angstrom to allow the respective independent behavior of the magnetizations of the respective magnetic material films around the film. The magnetizations of the soft magnetic material film 24 and the magnetization of the hard magnetic material film 21 behave respectively independently according to external magnetic fields and the directions of the relative magnetization change easily between a parallel state and antiparallel state, by which the gigantic magnetoresistance effect is obtd. The leaking magnetic fields are decreased by providing the gigantic magnetoresistance material film with the third ferromagnetic material film 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetoresistive material film for a magnetoresistive effect element used in a magnetic head, a position sensor, a rotation sensor, etc., and a method for adjusting the magnetization of the magnetoresistive material film.

[0002]

2. Description of the Related Art Conventionally, a Ni--Fe alloy thin film (permalloy thin film) has been known as a magnetoresistive (MR) effect material used for this kind of application, and the resistance change rate of the permalloy thin film is 2 to 2. 3% is typical. Therefore, in the future, a magnetoresistive effect material having a larger resistance change ratio (MR ratio) is desired in order to cope with the improvement of the linear recording density and the track density in the magnetic recording or the higher resolution of the magnetic sensor.

By the way, in recent years, a phenomenon called a giant magnetoresistive effect is caused by an alternating laminated film of Fe / Cr or Co / C.
It has been found in multilayer thin films such as u alternating laminated films. In these multilayer thin films, the magnetization of each ferromagnetic metal layer made of Fe, Co, etc. causes a magnetic interaction through the nonmagnetic metal layer made of Cr, Cu, etc. The magnetizations of the layers are coupled so that they remain antiparallel in the absence of an external magnetic field. That is, in these structures, the ferromagnetic metal layers that are alternately stacked with the non-magnetic metal layer in between are layered so that the magnetization directions are opposite to each other. Then, in these structures, when an appropriate external magnetic field is applied, the magnetization directions of the ferromagnetic metal layers change so as to be aligned in the same direction.

In the above structure, when the magnetizations of the respective ferromagnetic metal layers are in the antiparallel state and the parallel state, the interface between the Fe ferromagnetic metal layer and the Cr nonmagnetic metal layer or the Co ferromagnetic metal layer is used. It is said that the scattering of conduction electrons at the interface of the Cu nonmagnetic metal layer differs depending on the spin of the conduction electrons. Therefore, based on this mechanism, the electric resistance is high when the magnetization directions of the ferromagnetic metal layers are in the antiparallel state, and the electric resistance is low when the magnetization directions are in the parallel state, and the resistance change rate exceeds that of the conventional permalloy thin film. The so-called giant magnetoresistive effect is generated. Thus, these multi-layer thin films are fundamentally different from conventional Ni-Fe single-layer thin films by M
It has an R generation mechanism.

However, in these multilayer films, the magnetic interaction between the ferromagnetic metal layers that act so as to make the magnetization directions of the ferromagnetic metal layers antiparallel to each other is too strong. There is a problem in that a very large external magnetic field must be applied in order to make the magnetization directions of the two parallel. Therefore, a large change in resistance does not occur unless a strong magnetic field is applied, and satisfactory high sensitivity cannot be obtained when applied to a device that detects a minute magnetic field from a magnetic recording medium such as a magnetic head. There was a problem.

In order to solve this problem, the thickness of the non-magnetic metal layer made of Cr, Cu or the like is adjusted so that the magnetic interaction acting between the ferromagnetic metal layers is not excessively strengthened. It seems effective to control the relative direction of the magnetization of the magnetic metal layer by a method other than the magnetic interaction. Conventionally, as a technique for controlling the relative direction of such magnetization, by providing an antiferromagnetic layer such as FeMn, the direction of magnetization of one ferromagnetic metal layer is fixed, and the direction of magnetization of this ferromagnetic metal layer is fixed. A technique has been proposed which enables operation by a minute magnetic field by making the magnetic field hard to move with respect to an external magnetic field and by freely moving the magnetization direction of the other ferromagnetic metal layer.

FIG. 15 shows an example of a magnetoresistive sensor having a structure to which this kind of technology disclosed in Japanese Patent Laid-Open No. 6-60336 is applied. A magnetoresistive sensor A shown in FIG. 15 is configured by laminating a first magnetic layer 2, a nonmagnetic spacer 3, a second magnetic layer 4 and an antiferromagnetic layer 5 on a nonmagnetic substrate 1. And the magnetization direction B of the second magnetic layer 4 is fixed by magnetic exchange coupling by the antiferromagnetic layer 5, and the magnetization direction C of the first magnetic layer 2 is the second when there is no applied magnetic field. Is oriented at a right angle to the direction B of magnetization of the magnetic layer 4. However, since the magnetization direction C of the first magnetic layer 2 is not fixed, it can be rotated by an external magnetic field.

When an applied magnetic field h is applied to the structure shown in FIG. 15, the magnetization direction C of the first magnetic layer 2 rotates according to the direction of the applied magnetic field h as indicated by a dotted arrow, so that the first magnetic layer An angle difference occurs in the magnetization between the layer 2 and the second magnetic layer 4, which causes a resistance change, which allows magnetic field detection.

Next, as another example of the magnetoresistive sensor in which the magnetization direction of one magnetic layer is fixed and the magnetization direction of the other magnetic layer is free, as shown in FIG. An antiferromagnetic layer 7 made of NiO and a magnetic layer 8 made of Ni-Fe
A Cu non-magnetic metal layer 9 and a Ni-Fe magnetic layer 10.
And Cu non-magnetic metal layer 11 and Ni-Fe magnetic layer 1
A magnetoresistive sensor B having a structure in which 2 and an antiferromagnetic layer 13 of FeMn are sequentially stacked is known. In the structure of this example, the magnetizations of the ferromagnetic metal layers 8 and 12 adjacent thereto are fixed by the antiferromagnetic layers 7 and 13, respectively, and the nonmagnetic metal layers 9 and 11 are interposed between the ferromagnetic metal layers 8 and 12. The magnetization of the ferromagnetic metal layer 10 that is sandwiched between is configured to be rotatable according to an external magnetic field.

In the magnetoresistive sensor having the structure shown in FIG. 15 or 16, the electric resistances of the magnetoresistive sensor A and the magnetoresistive sensor B linearly change with high sensitivity in response to a minute change in the applied magnetic field. Further, as the first magnetic layer 2, Ni-
When a soft magnetic material such as Fe is used, its soft magnetic characteristics can be utilized, and there are advantages such as less hysteresis.

[0011]

However, as shown in FIG.
Alternatively, the magnetoresistive sensor having the structure shown in FIG.
The magnetization of the adjacent second magnetic layer 4 is fixed by the antiferromagnetic layer 5 of the above, or the upper and lower antiferromagnetic layers 7 and 13 of FeMn and NiO.
To fix the magnetization of the ferromagnetic metal layers 8 and 12 between them,
Since the structure is such that the magnetization of the magnetic layer 10 between them is free, there is a restriction that the number of Ni-Fe (magnetic layer) / Cu (nonmagnetic metal layer) interfaces that contribute to the giant magnetoresistive effect cannot be increased. However, there is a problem that the size of the MR ratio is restricted. Further, FeMn used as a constituent material of the antiferromagnetic layers 5 and 7 has a disadvantage in terms of corrosion resistance and environment resistance.

Next, as a modified structural example of the magnetoresistive sensor having the structure shown in FIGS. 15 and 16, as shown in FIG. 17, a non-magnetic layer 16 of Cu and a hard magnetic layer of Co are formed on a glass substrate 15. Material layer 17, non-magnetic layer 18 of Cu and Ni-Fe
A structure is known in which the soft magnetic material film 19 is repeatedly laminated a plurality of times. The magnetoresistive sensor having the structure shown in FIG.
By using the difference in coercive force between the hard magnetic material film 17 and the soft magnetic material film 19 to adjust the thickness of the non-magnetic layer 18 to a predetermined thickness, the magnetization directions of both magnetic layers 17 and 19 are made parallel. Alternatively, they can be antiparallel to each other, so that a giant magnetoresistive effect can be obtained. In the magnetoresistive sensor having this structure, the number of layers can be freely changed.
There is a feature that a larger MR ratio can be obtained than the magnetoresistive sensor having the structure shown in FIG.

However, in the magnetoresistive sensor having the structure shown in FIG. 17, when the hard magnetic material film 17 has a large coercive force, M
The R ratio is large, but on the other hand, the leakage magnetic flux is large, and the coercive force of the soft magnetic material film 19 is also large due to this influence. There was a problem that caused it.
Therefore, as a result of repeated studies by the present inventors in order to solve this problem, the high coercive force of the hard magnetic material film 17 affects the soft magnetic material film due to the leakage magnetic field from the hard magnetic material film 19 It is concluded that this is because the anisotropic dispersion of the magnetic material film 19 becomes large. Further, magnetostatic coupling occurs between the hard magnetic material film 17 and the soft magnetic material film 19, and the magnetization reversal of the soft magnetic material film 19 is caused by the hard magnetic material film 1.
It was concluded that this is because it was suppressed by 7.

The present invention has been made in view of the above circumstances, and a high MR ratio can be obtained by using a laminated structure capable of realizing a multilayer film structure of magnetic layers which could not be achieved by the conventional structure shown in FIG. 15 or 16. At the same time you can get
PROBLEM TO BE SOLVED: To provide a giant magnetoresistive material film and a method for adjusting the magnetization of the magnetoresistive material film by solving the problem of the stray magnetic field of the hard magnetic material layer which cannot be avoided in the conventional structure shown in FIG. The purpose is to do.

[0015]

In order to solve the above-mentioned problems, the invention according to claim 1 is a giant magnetoresistive material film in which a plurality of magnetic material films and non-magnetic material films are laminated, with a non-magnetic film interposed therebetween. Of the magnetic material films provided on both sides thereof, one magnetic material film is composed of a hard magnetic material film and the other magnetic material film is composed of a soft magnetic material film, and the non-magnetic film and the hard magnetic material film are formed. A third ferromagnetic material film having a high saturation magnetic flux density is provided between the two.

In order to solve the above-mentioned problems, the invention of claim 2 is a unit laminated film in which a hard magnetic material film, a third ferromagnetic material film, a non-magnetic film and a soft magnetic material film are laminated on a substrate. Is repeatedly laminated with a plurality of non-magnetic films or non-magnetic films and a soft magnetic material film interposed therebetween.

In a third aspect of the invention, the third ferromagnetic material film in the invention is selected from Co, Co-Fe alloy, Co-Fe-Ni alloy and Ni-Fe alloy. In the invention according to claim 4, as the constituent material of the hard magnetic material film, an alloy containing a Co--Pt alloy or a Co--Cr alloy as a main component and a trace amount of an additional element is used. In the invention according to claim 5, as a constituent material of the soft magnetic material film, a Ni-Fe alloy or a Ni-F alloy is used.
It is preferable to use an e-Co alloy or a Co-based amorphous alloy. Further, in the invention according to claim 6, it is preferable that the thickness of the third ferromagnetic material film is in the range of 0.5 to 2 with respect to the thickness of the hard magnetic material film of the above invention.

Next, the invention according to claim 7 is defined by claims 1 to 6.
The fourth ferromagnetic material film is interposed between the soft magnetic material film and the non-magnetic film described in any one of the above. Further, in the invention according to claim 8, a nonmagnetic thin film having a thickness of 30 Å or less is interposed between the third ferromagnetic material film according to any one of claims 1 to 7 and the hard magnetic material film. It is a thing.

Further, a material having the fourth ferromagnetic material film or a material having a non-magnetic film having a thickness of 30 angstroms or less is formed through the non-magnetic film or the non-magnetic film and the third ferromagnetic material film. It is also possible to adopt a structure in which the layers are repeatedly laminated.

Next, in the method of the present invention, a plurality of magnetic material films and non-magnetic films are laminated, and one of the magnetic material films provided on both sides of the non-magnetic film via the hard magnetic material film And the other magnetic material film is composed of a soft magnetic material film and the thickness of the non-magnetic film is adjusted to make the directions of magnetization of the hard magnetic material film and the soft magnetic material film relatively free, A third ferromagnetic material film having a high saturation magnetic flux density is provided between the non-magnetic film and the hard magnetic material film to block the leakage magnetic field from the hard magnetic material film and lower the coercive force of the entire laminated film. .

[0021]

In the present invention, since the third ferromagnetic layer is provided between the hard magnetic material film and the nonmagnetic film, the leakage magnetic field from the hard magnetic material film is reduced. Therefore, the soft magnetic material film provided via the third ferromagnetic material film and the nonmagnetic film is less likely to be affected by the leakage magnetic field. Therefore, the magnetization reversal of the soft magnetic material film is not suppressed by the hard magnetic material film, and the magnetization reversal of the soft magnetic material film is facilitated.

In order to exert more preferable MR characteristics in the above structure, the third ferromagnetic material film is
Co, Co-Fe alloy, Co-Fe-Ni alloy, Ni-Fe
It is preferable to use one selected from alloys. For the same reason, it is preferable to use, as a constituent material of the hard magnetic material film, an alloy containing either a Co—Pt alloy or a Co—Cr alloy as a main component and a trace amount of an additional element. For the same reason, as a constituent material of the soft magnetic material film, Ni-Fe alloy, Ni-Fe-
It is preferable to use an alloy made of either a Co alloy or a Co-based amorphous alloy.

Next, when the third ferromagnetic material film is provided in contact with the hard magnetic material film, the third ferromagnetic layer also has a property as a hard magnetic material film due to the influence of the hard magnetic material film. Therefore, in order to solve this problem, in order to solve this problem, it is necessary to add a layer between the hard magnetic material film and the third ferromagnetic material film.
The influence of the hard magnetic material film is suppressed by further providing a nonmagnetic thin film having a thickness of 0 angstrom or less. Here, the nonmagnetic thin film having a thickness of 30 angstroms or less means that between the hard magnetic material film and the third ferromagnetic material film, the magnetostatic or the indirect exchange mutual magnetism for trying to align the magnetizations of the two in parallel. This is because it causes an action.

The present invention will be described in more detail below. FIG. 1 shows a first structural example of a giant magnetoresistive material film according to the present invention. The giant magnetoresistive material film D of this example is shown.
Has a structure in which a hard magnetic material film 21, a third ferromagnetic material film 22, a nonmagnetic film 23, and a soft magnetic material film 24 are sequentially laminated on a nonmagnetic substrate 20.

The substrate 20 is made of glass, Si, Al.
₂ O ₃ , TiC, SiC, a sintered body of Al ₂ O ₃ and TiC,
It is composed of a non-magnetic material such as Zn ferrite. A coating layer or a buffer layer may be appropriately provided on the upper surface of the substrate 20 for the purpose of removing irregularities or waviness on the upper surface of the substrate or for improving the crystal matching of a film stacked thereover. good.

The hard magnetic material film 21 is made of an alloy containing a Co--Pt alloy or a Co--Cr alloy as a main component and a slight amount of an additive element, and is formed to a thickness of about several tens of angstroms. . The third ferromagnetic material film 2
2 is Co, Co-Fe alloy, Co-Fe-Ni alloy, N
consisting of one selected from i-Fe alloys,
The thickness of the hard magnetic material film 21 is in the range of 0.5 to 2 times, specifically 10 to 200 angstroms.

The non-magnetic film 23 is made of Cr, Au, Ag,
It is made of a non-magnetic material such as Cu and has a thickness of 20 to 40 angstroms. Here, if the thickness of the non-magnetic film 23 is less than 20 angstrom, magnetic coupling is likely to occur between the hard magnetic material film 21 and the soft magnetic material film 24. In addition, the non-magnetic material film 23 is 40
If the thickness is thicker than angstrom, the efficiency of conduction electrons passing through the interface between the non-magnetic material film and the magnetic material film, which is a factor that causes the magnetoresistive effect, decreases, that is, the magnetoresistive effect is reduced by the current shunting effect, which is preferable. Absent.

The soft magnetic material film 24 is made of any one of a Ni--Fe alloy, a Ni--Fe--Co alloy, and a Co-based amorphous alloy, and is formed to a thickness of about several tens of angstroms. More specifically, the Co-based amorphous alloy used here is Co- (Zr, Hf)-(N
(b, Ta) system and the like, which are excellent in soft magnetic characteristics.

In the giant magnetoresistive material film D having the structure shown in FIG. 1, by forming the nonmagnetic film 23 to the above-mentioned thickness, the magnetization of each magnetic material film around it can behave independently. Is being done. Therefore, the magnetization of the soft magnetic material film 24 and the magnetization of the hard magnetic material film 21 behave independently depending on the external magnetic field, and the mutual magnetization directions easily change between the parallel state and the antiparallel state. A large resistance change rate (MR ratio) can be obtained by the giant magnetoresistive effect. Further, in the above structure, a third magnetic layer is formed on the hard magnetic material film 21.
Since the ferromagnetic material film 22 is provided, the leakage magnetic field from the hard magnetic material film 21 can be shielded, and thus the leakage magnetic field in the entire giant magnetoresistive material film D can be reduced. Therefore, the magnetization of the soft magnetic material film 24 behaves independently of the magnetization of the hard magnetic material film 21 in response to a small external magnetic field, and even in a small magnetic field, the mutual magnetization directions are between the parallel state and the antiparallel state. Change easily.

FIG. 2 shows a second structural example of the giant magnetoresistive material film according to the present invention. The giant magnetoresistive material film E of this example is a hard magnetic material on a nonmagnetic substrate 20. Membrane 2
The first, third ferromagnetic material film 22, non-magnetic film 23, fourth ferromagnetic material film 25, and soft magnetic material film 24 are sequentially laminated. In the structure of this example, the non-magnetic substrate 20, the hard magnetic material film 21, the third ferromagnetic material film 22, the non-magnetic film 23, and the soft magnetic material film 24 are those used in the previous example. Is equivalent. This example is characterized in that the fourth ferromagnetic material film 25 is provided, but the fourth ferromagnetic material film 25 is formed thinner than the third ferromagnetic material film 22. By providing the fourth ferromagnetic material film 25, the rate of resistance change becomes better than that of the previous structure. That is, a NiFe alloy having a small coercive force is used as the soft magnetic material, and Co having a large resistance change rate (however, the coercive force is slightly large) is used only at the interface with the non-magnetic material film to obtain a soft magnetic property ( It is possible to obtain excellent characteristics in terms of both softness) and a large rate of change in resistance.

FIG. 3 shows a third structural example of the giant magnetoresistive material film according to the present invention. The giant magnetoresistive material film F of this example is a hard magnetic material on a nonmagnetic substrate 20. Membrane 2
1 and laminate unit U ₁ consisting of the third ferromagnetic material layer 22 and the nonmagnetic layer 23 and the soft magnetic material film 24. is formed, the laminate unit U ₁ has a plurality, and the non-magnetic layer 26 a third strong The magnetic material film 22 is repeatedly laminated to form a structure.

Even in the structure shown in FIG. 3, a giant magnetoresistive effect equivalent to that of the structure described above can be obtained. Moreover, in the structure shown in FIG. 3, since a plurality of laminated units U ₁ exhibiting a giant magnetoresistive effect are laminated, a larger magnetoresistive effect can be obtained than in the structure of the previous example.

In the structure of this example, the laminated unit U ₁ is laminated with the non-magnetic film 26 and the third ferromagnetic film 22 on the hard magnetic layer located at the lowermost layer of the upper laminated unit U _1. This is to prevent the material film 21 from exerting a magnetic adverse effect on the soft magnetic material film 24 of the uppermost layer of the laminated unit U ₁ therebelow. Therefore, the thickness of the nonmagnetic layer 26 provided at the boundary of the laminated unit U ₁ is 20 to 40 Å, and the thickness of the third ferromagnetic layer 22 is 0.5 to 2 that of the hard magnetic material film 21. The range is preferably doubled.

FIG. 4 shows a fourth structural example of the giant magnetoresistive material film according to the present invention. The giant magnetoresistive material film G of this example is a hard magnetic material on a nonmagnetic substrate 20. Membrane 2
1, the non-magnetic film 29, the third ferromagnetic material film 22, the non-magnetic film 23, and the soft magnetic material film 24 are sequentially laminated.

In the structure of this example, the non-magnetic substrate 2 is used.
0, the hard magnetic material film 21, the third ferromagnetic material film 22, the non-magnetic film 23, and the soft magnetic material film 24 are the same as those used in the previous example. This example is characterized in that the non-magnetic film 29 is provided, but this non-magnetic film 29 is provided.
Is formed thinner than the nonmagnetic layer 23, and its thickness is preferably about 5 to 20 angstroms.

By providing this non-magnetic film 29, the effect of the hard magnetic material film 21 is given only to the third ferromagnetic material film 22, and the effect on the soft magnetic material film 24 can be completely eliminated. .

[0037] Figure 5 shows a fifth structural example of the giant magnetoresistive material film according to the present invention, the structure of this example, this fourth laminated film of the structure shown in FIG. 2 as a laminate unit U ₂ In this structure, the ferromagnetic material film 25, the nonmagnetic film 23, and the third ferromagnetic material film 22 are repeatedly laminated. The repeated lamination structure has the effect of increasing the MR ratio.

[0038] Figure 6 shows a fifth structural example of the giant magnetoresistive material film according to the present invention, the structure of this example, the non-magnetic so a laminated film having the structure shown in FIG. 4 as a laminate unit U ₃ This is a structure in which a plurality of layers are repeatedly stacked with the film 23, the third ferromagnetic material film 22, and the nonmagnetic film 29 interposed therebetween. The repeated lamination structure has the effect of increasing the MR ratio.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. Using a high frequency magnetron sputtering device, a Co-Pt film (hard magnetic material film) having a thickness of 50 angstrom and a thickness of 25 to 100 is formed on a (100) surface of a silicon wafer substrate or a substrate made of glass.
An Angstrom Ni-Fe alloy film (third ferromagnetic material film), a 25 Angstrom Cu film (non-magnetic film), and a 50 Angstrom Ni-Fe alloy film (soft magnetic material film) are sequentially formed. By laminating, a first sample having a structure similar to that shown in FIG. 1 was obtained. The sputtering conditions are Co-
The Pt film and the Ni—Fe alloy film were 200 W, and the Cu film was 30 W, and the Ar gas pressure was 1 mTorr in both cases.

For comparison, a second sample having a structure in which the Ni—Fe alloy film was omitted from the first sample was prepared. Further, instead of the Ni—Fe alloy film used in the first sample, a third sample in which a Co film having a thickness of 50 angstrom is laminated, a Ni—Fe alloy film and a Cu film in the first sample A fourth sample in which a Co film having a thickness of 5 angstrom was added between the two was prepared.

Next, a Cu layer having a thickness of 25 Å and an N layer having a thickness of 50 Å were formed on the first sample.
A fifth sample having a structure in which an i-Fe alloy film is laminated, and a laminated film equivalent to the laminated film of the first sample is repeatedly laminated twice through the Cu layer and the Ni-Fe layer on the i-Fe alloy film. A sixth sample was prepared which was repeatedly laminated three times. Next, between the Co—Pt film and the Ni—Fe film of the first sample, the thickness 1
A seventh sample with a 0 angstrom Ta film added,
The thickness between the Co—Pt film and the Co film of the third sample is 1
An eighth sample was prepared with the addition of a 0 Å Ta film. After the above samples were formed into a film, they were magnetized with a magnetic field of 5 kOe or more, and thereafter, each characteristic was measured and evaluated.

FIG. 7 shows the magnetization curve (MH curve) of the first sample, and FIG. 8 shows the MR curve of the same sample. 9 shows the magnetization curve of the second sample, and FIG. 10 shows the MR curve of the second sample. Further, Table 1 below shows ΔR / R, ΔH, and (ΔR / R) / Δ of the first to eighth samples.
The measured value of each characteristic of H is shown. Here, ΔH is
In the giant magnetoresistive material film, when the magnetoresistive effect curve as shown in FIG. 8 is measured, the range of the magnetic field of the part where one curve rises almost linearly is shown.

As is clear from the comparison between the characteristics shown in FIGS. 7 and 8 and the characteristics shown in FIGS. 9 and 10, the first sample has a Co--Pt alloy film (hard magnetic material) as compared with the second sample. Since the leakage magnetic field of the film) can be suppressed, the value of ΔH shown in FIG. 8 is smaller than the value of ΔH shown in FIG. Also, comparing the values shown in Table 1,
The ΔH of the sample of 5 is 5 Oe, while the ΔH of the second sample is 85 Oe, which is a large difference. Therefore, the structure of the first sample changes the magnetic resistance with a magnetic field much smaller than that of the conventional structure, and is suitable for a magnetic head for detecting a minute magnetic field. Further, since a step is seen in the magnetization curve as shown in FIG. 7, in the first sample, the magnetization directions of the Co—Pt alloy film of the hard magnetic material film and the Ni—Fe alloy film of the soft magnetic material film are different. It was revealed that they behave independently.

[0044]

[Table 1]

Further, as is clear from the results shown in Table 1, the ΔH of the second sample, which is a comparative sample, is 85 Oe.
On the other hand, the ΔH values of the first and third to eighth samples according to the present invention are all low, showing excellent values. Therefore, since any structure according to the present invention causes a resistance change in a magnetic field lower than that of the structure of the conventional example, it is apparent that the structure can be applied to a magnetic head, a position sensor, a rotation sensor or the like that can operate in a minute magnetic field. . Further, by providing the Co layer as in the third and fourth examples, it was possible to increase the value of ΔR / R without increasing the value of ΔH. Further, it has been clarified that the value of ΔR / R can be improved while keeping ΔH small by adopting the repeated laminated structure as in the fifth example and the sixth example.

Next, in the structure of the first sample, the relationship between the thickness of the Ni—Fe alloy film provided as the third ferromagnetic material film and ΔH is examined, and the result is shown in FIG. As is clear from the results shown in FIG. 11, ΔH tends to decrease as the thickness t of the third ferromagnetic material film made of a Ni—Fe alloy increases, but the value of this thickness t is 50 angstroms. ΔH decreases sharply up to
The decrease will be saturated.

From this experimental result, it is found that it is most preferable to set the thickness of the third ferromagnetic material film to 50 angstroms or more. However, ΔH of the conventional structure shown in Table 1 is 85 Oe, and The thickness of the ferromagnetic material film of 3 is 1
Considering the decrease rate of the ΔH amount in the range of 0 to 50 Å, the thickness of the third ferromagnetic material film is set to Co
It can be judged that it is preferable to set the thickness of the hard magnetic material film of -Pt to 0.5 or more.

Next, under the same conditions as in the above case, Ni
FIG. 12 shows the relationship between the thickness of the —Fe alloy film and ΔMR. From this figure, it is clear that it is advantageous that the third ferromagnetic material film is thin in order to obtain a large ΔMR. Therefore, taking the results shown in FIG. 11 into consideration, it became clear that the thickness of the third ferromagnetic material film is preferably about 0.5 to 2 times the thickness of the hard magnetic material film.

Next, under the same conditions as in the above case, Ni
FIG. 13 shows the relationship between the film thickness of the -Fe alloy film and the value of ΔMR / ΔH.
Shown in From this figure, it can be seen that the value of ΔMR / ΔH shows a peak when the thickness of the Ni—Fe alloy film is in the vicinity of 50 Å.

Next, FIG. 14 shows the magnetization curve (MH curve) shown in FIG. 7 for the giant magnetoresistive material film.
If the magnetic field strength at the inflection point at the left end of the curve step in the fourth quadrant is defined as H _CS, and the magnetic field strength at the intersection of the MH curve and the horizontal axis is defined as H _CH , the value of H _CS, and shows the results of measuring the film thickness dependence on Ni-Fe alloy film of the values of H _CH. As is clear from this figure, as the thickness of the Ni-Fe alloy film increases, H
_It is clear that both the _CS and H _CH values tend to decrease. Therefore, as described above, the thickness of the third ferromagnetic material film is equal to the thickness of the Co--Pt hard magnetic material film of 0.
It can be judged that the range is preferably 5 to 2 times.

[0051]

As described above, according to the present invention, since the third ferromagnetic layer is provided between the hard magnetic material film and the non-magnetic film, the leakage magnetic field of the hard magnetic material film can be reduced. .
Therefore, the soft magnetic material film provided via the third ferromagnetic material film and the non-magnetic film is less susceptible to the influence of the leakage magnetic field, so that the magnetization reversal of the soft magnetic material film is suppressed by the hard magnetic material film. It becomes difficult, and the magnetization reversal of the soft magnetic material film is facilitated. Therefore, the resistance changes with a smaller magnetic field than the conventional structure in which the third ferromagnetic material film is not provided. Therefore, the structure of the present invention has a useful feature for a magnetic head, a magnetic sensor, and a rotation sensor for detecting a minute magnetic field.

In the above structure, in order to exert more preferable MR characteristics, the third ferromagnetic material film is
Co, Co-Fe alloy, Co-Fe-Ni alloy, Ni-Fe
It is preferable to use one selected from alloys. For the same reason, it is preferable to use, as a constituent material of the hard magnetic material film, an alloy containing either a Co—Pt alloy or a Co—Cr alloy as a main component and a trace amount of an additional element. For the same reason, as a constituent material of the soft magnetic material film, Ni-Fe alloy, Ni-Fe-
It is preferable to use an alloy made of either a Co alloy or a Co-based amorphous alloy.

The thickness of the hard magnetic material film is
By making the thickness of the ferromagnetic material film of 0.5 to 2 times, it is possible to obtain an excellent giant magnetoresistive material film whose resistance changes sensitively even in a low magnetic field region.

Next, in the present invention, the third ferromagnetic material film is provided in contact with the hard magnetic material film, but the third ferromagnetic layer is also formed as a hard magnetic material film due to the influence of the hard magnetic material film. Therefore, a nonmagnetic thin film having a thickness of 30 angstroms or less is further provided between the hard magnetic material film and the third ferromagnetic material film. With this structure, the magnetic influence of the hard magnetic material film on the third ferromagnetic material film can be suppressed. Here, by setting the thickness of the non-magnetic thin film to 30 angstroms or less,
Between the hard magnetic material film and the third ferromagnetic material film, it is possible to generate a magnetostatic or exchange coupling interaction that attempts to align the magnetizations of the two in parallel.

Next, in the present invention, a structure in which the fourth ferromagnetic material film is interposed between the soft magnetic material film and the non-magnetic film can be adopted, and the third ferromagnetic material film and the hard magnetic film can be formed. A structure in which a non-magnetic thin film having a thickness of 30 Å or less is interposed between the material film and the material film can also be used. With these structures, the rate of resistance change can be improved, and the influence of the stray magnetic field of the hard magnetic material layer can be removed more reliably.

Next, a laminate of the soft magnetic material film, the non-magnetic film, the third ferromagnetic material film and the hard magnetic material film is used as a laminated unit, or the soft magnetic material film of the laminated unit is not laminated with the soft magnetic material film. A structure in which a fourth ferromagnetic material film is provided between the magnetic film and the magnetic film is used as a laminated unit, and further, a non-magnetic film is provided between the hard magnetic material film and the third ferromagnetic material film of the laminated unit. A giant magnetoresistive material film having a multi-layered structure can be obtained by repeatedly stacking the above structure as a laminated unit through a nonmagnetic layer or a nonmagnetic layer and a third ferromagnetic material film. Since such a multi-layered giant magnetoresistive material film includes a plurality of portions that have a mechanism for generating a giant magnetoresistance, it is possible to obtain a larger resistance change than that of a single-layered structure. An excellent giant magnetoresistive material film can be obtained for a magnetic head for detecting a magnetic field or for a minute magnetic field sensor.

Next, according to the method of the present invention, of the magnetic material films provided on both sides of the non-magnetic film, one magnetic material film is composed of a hard magnetic material film and the other magnetic material film is made of a soft magnetic material film. Since the magnetic material film is used and the thickness of the non-magnetic material film is adjusted, the direction of magnetization of the soft magnetic material film can be made relatively free relative to the direction of magnetization of the hard magnetic material film. Further, by providing a third ferromagnetic material film having a high saturation magnetic flux density between the non-magnetic film and the hard magnetic material film, it is possible to block the leakage magnetic field from the hard magnetic material film, and to protect the entire laminated film. The magnetic force can be reduced, and a large resistance change can be generated even in a low magnetic field.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first structural example of a giant magnetoresistive material film according to the present invention.

FIG. 2 is a cross-sectional view showing a second structural example of the giant magnetoresistive material film according to the present invention.

FIG. 3 is a cross-sectional view showing a third structural example of the giant magnetoresistive material film according to the present invention.

FIG. 4 is a sectional view showing a fourth structural example of a giant magnetoresistive material film according to the present invention.

FIG. 5 is a sectional view showing a fifth structural example of a giant magnetoresistive material film according to the present invention.

FIG. 6 is a sectional view showing a sixth structural example of a giant magnetoresistive material film according to the present invention.

FIG. 7 is a diagram showing a magnetization curve of a first sample manufactured in an example.

FIG. 8 is a diagram showing an MR curve of the first sample.

FIG. 9 is a diagram showing a magnetization curve of a second sample manufactured as a comparative example.

FIG. 10 is a diagram showing an MR curve of the second sample.

FIG. 11 is a diagram showing the relationship between the film thickness of a third ferromagnetic material film and ΔH.

FIG. 12 is a diagram showing the relationship between the film thickness of a third ferromagnetic material film and ΔMR.

FIG. 13 is a diagram showing the relationship between the film thickness of a third ferromagnetic material film and ΔMR / ΔH.

FIG. 14 is a diagram showing a relationship between a film thickness of a third ferromagnetic material film and H _CS and H _CH .

FIG. 15 is an exploded view showing a first example of a conventional multilayer film for a magnetoresistive effect element.

FIG. 16 is a sectional view showing a second example of a conventional multilayer film for a magnetoresistive effect element.

FIG. 17 is a sectional view showing a third example of a conventional multilayer film for a magnetoresistive effect element.

[Explanation of symbols]

 20 substrate 21 hard magnetic material film 22 third ferromagnetic material film 23 non-magnetic film 24 soft magnetic material film 25 fourth ferromagnetic material film 26 non-magnetic film 29 non-magnetic layer U1, U2, U3 laminated unit

Claims (10)

[Claims] 1. A giant magnetoresistive material film in which a plurality of magnetic material films and nonmagnetic films are laminated, and one of the magnetic material films provided on both sides of the nonmagnetic film is a hard magnetic material. A magnetic material film, the other magnetic material film is composed of a soft magnetic material film, and a third ferromagnetic material film having a high saturation magnetic flux density is provided between the non-magnetic film and the hard magnetic material film. A giant magnetoresistive material film characterized by the above. 2. A unit laminated film in which a hard magnetic material film, a third ferromagnetic material film, a non-magnetic film and a soft magnetic material film are laminated on a substrate, a plurality of non-magnetic films or non-magnetic films. A giant magnetoresistive material film characterized by being repeatedly laminated through a soft magnetic material film. 3. As the third ferromagnetic material film, Co,
The giant magnetoresistive material film according to claim 1 or 2, wherein an alloy selected from a Co-Fe alloy, a Co-Fe-Ni alloy, and a Ni-Fe alloy is used. 4. An alloy containing, as a constituent material of the hard magnetic material film, a Co--Pt alloy or a Co--Cr alloy as a main component and a small amount of an additive element is used. The giant magnetoresistive material film described in 1, 2, or 3. 5. The material of the soft magnetic material film is made of any one of a Ni—Fe alloy, a Ni—Fe—Co alloy and a Co-based amorphous alloy. The giant magnetoresistive material film described in 2, 3, or 4. 6. The ratio of the thickness of the third ferromagnetic material film to the thickness of the hard magnetic material film is set in the range of 0.5 to 2 as claimed in claim 1. The giant magnetoresistive material film according to 4 or 5. 7. A giant film according to claim 1, wherein a fourth ferromagnetic material film is interposed between the soft magnetic material film and the non-magnetic film. Magnetoresistive material film. 8. A non-magnetic thin film having a thickness of 30 angstroms or less is interposed between the third ferromagnetic material film and the hard magnetic material film.
The giant magnetoresistive material film according to 5, 6, or 7. 9. A giant magnetic material comprising the giant magnetoresistive material film according to claim 7 or 8 which is repeatedly laminated with a non-magnetic film or a non-magnetic film and a third ferromagnetic material film interposed therebetween. Resistive material film. 10. A plurality of magnetic material films and non-magnetic films are laminated,
Among the magnetic material films provided on both sides of the non-magnetic film, one magnetic film is made of a hard magnetic material film, the other magnetic film is made of a soft magnetic material film, and the thickness of the non-magnetic film is The third ferromagnetic material film having a high saturation magnetic flux density is provided between the non-magnetic film and the hard magnetic material film while adjusting the magnetization directions of the hard magnetic material film and the soft magnetic material film relatively freely. Is provided to block the leakage magnetic field from the hard magnetic material film and reduce the coercive force of the entire laminated film to adjust the magnetization of the magnetoresistive material film.