JP2554444B2 - Uniaxial magnetic anisotropic thin film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniaxial magnetic anisotropic thin film having excellent soft magnetic characteristics in a high frequency range and having a large electric resistivity and saturation magnetization.

[0002]

2. Description of the Related Art In recent years, efforts have been actively made to increase the operating frequency of electronic equipment. However, there are no known magnetic materials used in transformers, inductors, magnetic heads, etc. that have sufficient characteristics in the high frequency range.
Therefore, there are many restrictions on the use of these components in the high frequency range. Generally, in the high frequency region of 1 MHz or more, a large loss occurs due to the eddy current flowing through the magnetic material itself. Since the metal-based magnetic material has a small electric resistance, it has a large eddy current loss and is difficult to use in a high frequency range. On the other hand, oxide-based magnetic materials such as ferrite and garnet have a very high electric resistance, so that loss due to eddy current is relatively unlikely to occur. However, it is difficult to obtain a high magnetic permeability, and the saturation magnetic flux density is small, so that the natural resonance frequency is low, and there are many restrictions on use in a high frequency range.

There is great expectation for a magnetic material having a high saturation magnetic flux density and good high-frequency characteristics, and methods for increasing the electric resistance of a metallic magnetic material have been proposed.
For example, a method for obtaining an amorphous alloy film in which ceramics are dispersed by co-sputtering of metal and ceramics has been proposed in JP-A-60-152651, and further, J.
Appl.Phys.63 (8), 15 April 1988, Fe-B ₄ C based dispersion film, J.AppL.Phys.67 (9), 1 May 1990 Co _0.4 Fe.
_{It is shown that the 0.4} B _0.2 -SiO ₂ -based dispersion film has both high specific resistance and soft magnetic properties. Further, good soft magnetic characteristics cannot be obtained with a thick single-layer film. Co _0.95 Fe _0.05
-By using a BN-based dispersion film as a magnetic layer having a thickness of 0.1 μm or less, soft magnetic properties can be obtained, and by stacking thin films with a non-magnetic intermediate layer interposed, soft magnetic properties can be obtained even with a thick film. It is disclosed in Japanese Patent Application Laid-Open No. 4-142710.

On the other hand, a method of obtaining an amorphous alloy film having a high electric resistivity by reactive sputtering with N ₂ or O ₂ gas is disclosed in JP-A-54-94428.
In addition, it has been found in many alloy systems that the addition of N ₂ gas at the time of forming a thin film is effective in improving the soft magnetic properties. For example, IEEE TRANS. ON MAG. MAG-20 1451 (198
It is disclosed in 4).

[0005]

A magnetic material used in a high frequency range is required to have high electric resistance and high saturation magnetization. In addition, it is desirable that the magnetostriction constant of the material be as close to zero as possible in order to minimize deterioration of the soft magnetic characteristics due to processing strain. However, the previously reported Fe / B ₄ C based dispersion film, Co _0.4 Fe _0.4 B _0.2 / S
It has been shown that all of the iO ₂ -based dispersion films have excellent soft magnetic characteristics when they are in the amorphous phase, but they have a very large positive magnetostriction of 10 −5 or more. On the other hand, a Co _0.95 Fe _0.05 / BN dispersion film was developed for the purpose of achieving both zero magnetostriction and high resistance. This system has a large saturation magnetic field and a large coercive force in a thick single layer film of 0.1 μm or more and has a soft magnetic property. Not shown. Therefore, it has been shown that soft magnetic properties can be obtained by stacking via a non-magnetic layer, but on the other hand, this means that the saturation magnetization of the entire film is reduced and the process becomes complicated. Included points.

On the other hand, in recent years, it has been actively studied to develop a soft magnetic material having a small magnetostriction constant by refining the crystal grains of an Fe-based alloy. For example, Japanese Patent Laid-Open No. 3-11
In Japanese Patent No. 2104, a Fe alloy in which Zr or Ta carbide is dispersed is obtained by subjecting an amorphous phase produced by sputtering to crystallization heat treatment, and the saturation magnetostriction is small and the soft magnetic property is excellent. It is shown. By further adding Al to this alloy thin film, 100 to 20
It has been shown that a specific resistance of 0 μΩcm can be obtained, but it cannot be said to be sufficient to suppress eddy current loss in the high frequency range, and a high specific resistance has a problem that the saturation magnetic flux density is small. there were. In addition, these thin films can be used after undergoing a crystallization heat treatment of an amorphous alloy thin film.
Since this heat treatment temperature is as high as 500 ° C. or higher, it cannot be used for a substrate having no heat resistance or an element which is not exposed to high temperature.

On the other hand, a method of forming a Fe-based alloy in an atmosphere containing N or O in order to obtain fine crystal grains immediately after film formation is disclosed in Japanese Patent Laid-Open No. 3-120339. . However, the electrical resistivity of the thin films obtained by these methods was not large enough to suppress eddy current loss in the high frequency range. FeH is also included in the summary of lectures at the 112th Spring Meeting of the Japan Institute of Metals, 1993, p84 (143).
It has been shown that an amorphous alloy thin film having a high electric resistivity and an excellent soft magnetic property can be produced by sputtering the f alloy in an atmosphere containing O ₂ , but there is no description regarding magnetostriction.

By the way, a major cause of magnetic core loss in the high frequency range is resonance loss in addition to the above-mentioned eddy current loss. This resonance loss is suppressed as the saturation magnetic flux density and the anisotropic magnetic field are higher. From this point, an Fe-based alloy having a large saturation magnetic flux density was promising as a high-frequency magnetic core, but C
Since it was difficult to increase the anisotropic magnetic field as compared with the case of using an o-group or the like, a material having sufficient high frequency characteristics has not been reported so far.

As described above, there has been a demand for a high-frequency magnetic thin film material having a large electric resistivity, a small magnetostriction, and a good soft magnetic property even in a thick single layer film. The present invention has been made in view of the above points, and an object of the present invention is to provide a uniaxial magnetic anisotropic thin film having excellent soft magnetic characteristics in a high frequency range and large electric resistivity and saturation magnetization.

[0010]

Means and Action for Solving the Problems The present inventors have
As a result of diligent efforts in view of the above circumstances, a composite dispersion film of oxide-based ceramics and bcc-Fe has a high electric resistivity, a small magnetostriction, and a single-layer film having a thickness of 0.1 μm or more is good. It was found that soft magnetic characteristics can be obtained. Furthermore, they have found that uniaxial magnetic anisotropy can be imparted by forming these thin films under a DC magnetic field. The anisotropic magnetic field at this time was so large as to be unthinkable with the conventional Fe-based magnetic thin film, and sometimes exceeded 100 Oe. It was found that these films have an extremely high natural resonance frequency due to a large anisotropic magnetic field, and have an excellent feature that soft magnetic characteristics do not deteriorate even at several 100 MHz or more, and the present invention has been completed. It is a thing.

[0011]

EXAMPLES Examples of the present invention will be described below with comparison with a conventional composite dispersion film and the like. BN, SiC, S
A film made by simultaneously sputtering ceramics such as io ₂ and metals such as Fe and Fe alloys has a unique network-like crystal structure when observed in detail with a transmission electron microscope. To be found. This is an amorphous or crystalline cluster mainly composed of a metal covered with a grain boundary phase mainly composed of a ceramic, and these films have an electrical ratio 2 to 10 ⁴ times higher than that of an ordinary metal thin film. This organization is the main reason for the resistance. The present inventors have examined in detail the effect of the combination of Fe and ceramics on the crystal structure and magnetic properties of the film. As a result, the following was newly found. The film in which the clusters after film formation are amorphous exhibits high electric resistivity and soft magnetism and large positive magnetostriction of 10 ⁻⁵ , and this tendency does not depend on the type of ceramics. On the other hand, when the clusters are crystalline, the type of ceramics greatly affects the magnetic properties. That is, in the case of a composite dispersion film made of a nitride or a carbide such as BN or SiC, the film that is crystalline in the formed state does not exhibit soft magnetism. On the other hand, a thin film in which the amorphous phase is heat-treated and the clusters are crystallized into the bcc-Fe phase exhibits soft magnetism, and the saturation magnetostriction constant decreases with crystallization, and 10 ^-6
However, even if heat treatment is performed in a large magnetic field of 1 kOe or more, it is difficult to impart uniaxial magnetic anisotropy, and therefore high frequency characteristics are not sufficient. For example, Fe—Si ₃ N ₄ system loses uniaxial anisotropy in the process of crystallization from amorphous. Further, the Fe-AlN-based thin film is either an amorphous film or a crystal film after heat treatment, and only an isotropic film can be obtained. The uniaxial magnetic anisotropy plays a more important role than the electrical resistivity in the high frequency range of several tens of MHz or more. That is, a material having a small anisotropic magnetic field has a low natural resonance frequency and tends to have a large dispersion of the anisotropic magnetic field, resulting in high loss and not suitable for use in a high frequency range.

On the other hand, the composite dispersion film composed of Fe and an oxide or fluoride shows good soft magnetism even when the film in which the clusters are in the bcc-Fe phase is formed. Hereinafter, it will be explained as an example Fe-SiO ₂ system. A film containing a large amount of SiO ₂ becomes amorphous like a carbide-based or nitride-based film,
It exhibits soft magnetic properties. Further, a film containing less SiO ₂ becomes crystalline, but among them, a film mainly composed of the bcc-Fe phase exhibits soft magnetism in the as-formed state. The saturation magnetostriction of these films is on the order of +10 ^-6 , which is smaller than that of carbide-based or nitride-based amorphous films. In particular, the film containing bcc-Fe as the main phase is about + 3 × 10 ^-6, which is sufficiently small. . Also,
Unlike nitride-based and carbide-based films, uniaxial magnetic anisotropy can be easily added to these films by applying a static magnetic field during film formation. The film is not so large as about 15 Oe, but bcc-
Films containing Fe as the main phase are very large, and some of them exceed 100 Oe. No case has been reported so far in which such a large saturation magnetic field was obtained with excellent soft magnetic properties. The saturation magnetic flux density of this film is 10-18 kG
Therefore, the theoretical natural resonance frequency is 2 GHz or more, and the electrical resistivity is also as large as 100 to 1000 μΩcm, so that the eddy current loss is small and the high frequency characteristics are excellent. Thus, the fact that the film containing bcc-Fe as the main phase exhibits soft magnetism and large anisotropy means that Fe-SiO
It is not limited to the _two types, but is generally found in composite dispersion films composed of Fe and oxide-based or fluoride-based ceramics. The present invention has been made based on the above findings, and is described in "General formula Fe _100-xyz M _x N _y
L _z (atomic%), M is Be, B, Mg, Al,
Si, Ca, Ti, Y, Zr, Mo, In, Sn, C
s, Ba, La, Hf, Ta, Bi, Pb, W is one or more elements selected, and L is one or two elements selected from O and F And the respective atomic ratios are 5 ≦ x ≦ 250 0 ≦ y ≦ 15 15 ≦ z ≦ 35 28 ≦ x + y + z ≦ 50, and their crystal structures are mainly bcc-Fe structure and M oxide phase or fluorine. Compound phase, and an anisotropic magnetic field of 25
A high-resistance soft magnetic thin film having Oe or more. 』Is the main idea.

The thin film of the present invention has a network structure in which a metallic crystalline cluster is covered with a grain boundary phase mainly composed of ceramics. From the state analysis such as XPS, it is clear that the composition of this grain boundary strongly depends on the composition of the ceramic target, and the metal cluster is not an elemental Fe but an alloy of M element and Fe given from the ceramic target. It has become. That is, when the ceramic target is changed, the composition of both the metal cluster phase and the grain boundary phase changes greatly. However, in the present invention, M is Be, B, Mg, Al, Si, Ca, Ti, Y, Zr,
Mo, In, Sn, Cs, Ba, La, Hf, Ta, B
Soft magnetic characteristics can be obtained as long as it is selected from i, Pb, and W. This can be understood by explaining the cause of the soft magnetic property in the thin film of the present invention as follows. That is, bc having high crystal symmetry
The c-Fe phase is disturbed by grain growth due to the network structure of the ceramic grain boundaries and becomes fine crystals. It is well known that FeNbCuSiB alloy and the like show that a bcc-Fe alloy composed of microcrystals of an appropriate size exhibits soft magnetic characteristics because the magnetic anisotropy of each microcrystal is canceled. In the thin film of the present invention, the grain boundary phase mainly acts as a “frame” for accommodating the bcc phase, and the alloying of the metal phase is also bc.
It can be understood that there is no composition dependence, considering that the soft magnetic properties are exhibited as long as the c phase is maintained. Therefore, in the present invention, the composition of M and L is mainly defined by the formation of the network structure of grain boundaries. In order to form a network structure, M needs to be 5 atomic% or more. If it is less than 5%, soft magnetism cannot be obtained, and if it exceeds 25 atomic%, the saturation magnetic flux density becomes too small. Not preferable. The amount of L varies depending on the amount of M and its type.
If it is less than atomic%, a network structure cannot be formed, and if it exceeds 35 atomic%, it is not preferable because the soft magnetism is deteriorated or an abnormal loss occurs in a high frequency range. On the other hand, as long as the cluster can maintain the bcc-Fe structure, there is no problem even if other elements form a solid solution. This does not limit the type of ceramic target, and even if the Fe target is changed to the Fe alloy target,
It is shown that soft magnetic characteristics can be obtained. In fact, even if Fe is replaced with Co, if the amount of replacement is within 70% that can maintain the bcc structure, soft magnetic characteristics can be obtained and the saturation magnetic flux density can be increased. For the same reason, other elements may be Fe as long as they do not hinder the bcc structure.
Addition to is included in the scope of the present invention.
On the other hand, in the present invention, N exerts a very important action which is not present in other elements. One of them is that N also acts as an amorphous forming element, so that N is made amorphous when added in excess of 25 atom%. In this case, the saturation magnetostriction constant exceeds 10 ⁻⁵ and becomes large, and the perpendicular magnetic anisotropy is generated, so that the soft magnetism is lost. In addition, the anisotropic magnetic field decreases as the amount of N increases in the range of 25 atomic% or less where soft magnetism is maintained. Therefore, in the thin film of the present invention, the magnitude of the anisotropic magnetic field can be controlled by the composition of N in the film. In the high frequency band, the magnetization process due to rotational magnetization is dominant, and the permeability is inversely proportional to the anisotropic magnetic field. Therefore, it is very effective that the anisotropic magnetic field can be adjusted to an appropriate level. However, when N exceeds 15 atomic%, an isotropic film is formed, and the characteristics of the present invention are lost, which is not suitable. In order to obtain a large uniaxial magnetic anisotropy of 25 Oe or more in the present invention, the N concentration in the film is 13
It is preferably at most atomic%. The addition of N in the film is
This can be performed by adding a nitride target, but can also be adjusted by adding a gas containing N to the sputtering gas. In addition to the addition of N described above in the present invention, the anisotropic magnetic field can be adjusted by the substrate temperature, the sputtering pressure, the applied magnetic field, etc. during film formation, and the film forming conditions can be adjusted by considering the frequency to be used and the magnetic permeability. May be selected appropriately.

Hereinafter, the present invention will be described in more detail with reference to specific examples. [Example-1] Fe having a diameter of 4 inches and a purity of 99.9%
On the disk, the purity is 99.9 so that the coverage is 30%.
% Of a SiO ₂ plate in a fan shape to produce a Fe—SiO ₂ thin film by high frequency sputtering. The film forming conditions were set as shown in Table 1 below.

Table-1 Sputtering pressure 1.0 × 10 ^-2 Torr Input power 90 W Substrate temperature 20 ° C. (water cooling) Substrate Corning # 7059 Thickness 0.
5 mm Film thickness 2.4 μm Sputtering gas flow rate Ar 10 CCM Applied magnetic field 1 pair of permanent magnets (40 Oe) The obtained sample is an X-ray diffractometer RAD-3A manufactured by Rigaku Denki Co., Ltd.
The tissue was identified by. The results are shown in Figure 2. 2θ is 44
A broad diffraction peak corresponding to the (110) plane of bcc-Fe is observed in the vicinity of °. Next, FIG. 3 shows the results of observing the microstructure of the thin film with a transmission electron microscope H-9000 NAR manufactured by Hitachi Ltd. A network-like structure consisting of clusters having a grain size of about 50 angstroms and grain boundaries having a thickness of several angstroms is observed, and it is recognized that this thin film is composed of two phases. Further, it was confirmed from the electron diffraction pattern that these were a bcc-Fe phase and a compound phase similar to SiO ₂ . When the composition of the entire film was analyzed by Rutherford backscattering, the composition was Fe ₆₄ Si ₁₁ O ₂₄ (atomic%). Next, the state of each element was analyzed by an X-ray spectroscopic analyzer ESCA-5600 manufactured by ULVAC-PHI. From the peak profile of the binding energy of Si _2p , it can be seen that Si has two states, one that forms a metal phase by binding with Fe and one that forms a SiO _x phase by binding with O. all right. It was confirmed that the thin film thus obtained had a fine structure in which the metallic phase mainly composed of FeSi having the bcc crystal structure was covered with the amorphous SiO _x phase. Next, the DC magnetic characteristics were measured with a sample vibration type magnetometer BHV-30SS manufactured by Riken Denshi Co., Ltd. FIG. 4 shows the results. The two data in the figure represent the results measured by exciting in parallel (//) and perpendicular (|) to the magnetic field application direction during film formation. The sample has a uniaxial magnetic anisotropy in which the direction of the magnetic field applied during film formation is parallel to the easy axis of magnetization, and its anisotropic magnetic field (Hk) is 83 Oe.
And was a very big one. Coercive force of sample (Hc)
Is sufficiently small as 2.0 Oe in the easy axis direction (Hce) and 0.4 Oe in the hard axis direction (Hch), and has a small anisotropy dispersion because the linearity of the hysteresis curve is good. Recognize. The saturation magnetic flux density (Bs) is also 1
It is sufficiently large as 5.2 kG. Electric resistivity of this film (ρ)
Was measured by the DC 4-terminal method to obtain 285 μΩcm
It was 2-3 times higher than that of a normal amorphous alloy. Next, the frequency characteristics of the magnetic permeability in the direction of the hard axis are analyzed by the Yokogawa Hewlett-Packard network analyzer 41.
It was measured by the parallel line method with 95A. For a detailed explanation of this method, see the Applied Magnetics Society of Japan, Vol.
17, No. 2, p497 (1993). The results are shown in Fig. 5. Despite the fact that the film was quite thick, it showed good frequency characteristics that did not deteriorate up to 500 MHz. This is because this thin film has a high saturation magnetic flux density, an anisotropic magnetic field, and a high electrical resistivity, and is homogeneous with little disorder. These characteristics are described in Journal of Applied Magnetics of Japan, Vol. 15, No. 2, p327 (19
It was close to the theoretical value obtained from Bs, Hk, ρ, and film thickness by the method disclosed in 91).

Next, the saturation magnetostriction constant of this film was measured by an optical lever type saturation magnetostriction measuring device MS-7 manufactured by Naruse Kagaku Kikai Co., Ltd.
It measured under the magnetic field of Oe. In this measurement, since it was very difficult to actually measure the Young's modulus of the film, the value of 12 × 10 ³ kg / mm ² of FeSiB ribbon was adopted and calculated. As a result, the magnetostriction was + 3.0 × 10 ^−6, which was a very small value of 1/5 to 1/10 of the conventional Fe-based amorphous alloy. [Comparative Example-1] Fe having a diameter of 4 inches and a purity of 99.9%
A thin film was produced by high frequency sputtering using a composite target in which a Si ₃ N ₄ plate was installed in a fan shape so that the coverage rate was 40% on the disk. Other film forming conditions were set as shown in Table 2 below.

Table-2 Sputtering pressure 1.0 × 10 ^-2 Torr Input power 90 W Substrate temperature 20 ° C. Substrate Corning # 7059 Thickness 0.
5 mm Film thickness 0.8 μm Sputtering gas flow rate Ar 10 CCM Applied magnetic field 1 pair of permanent magnets (40 Oe) The obtained thin film was in the bcc-Fe phase as in Example 1 as shown in FIG. When the composition of the film was analyzed by Rutherford backscattering, it was Fe ₆₅ Si ₂₁ N ₁₄ (atomic%). The DC magnetic hysteresis curve of this thin film by VSM is shown in FIG. The sample has a large coercive force of 14 Oe,
It showed neither soft magnetic properties nor uniaxial magnetic anisotropy. In addition, 1
Since the magnetization was not saturated at 00 Oe, the saturation magnetostriction constant could not be measured. In the film formation conditions of Example -2 Example -1 was prepared and Fe-SiO ₂ -N film while adding N ₂ to the sputtering gas. The crystal structure and electromagnetic characteristics of the obtained film were measured in the same manner as in Example-1. The composition analysis of the film was performed by Rutherford backscattering method. N in the film increased as the N ₂ gas flow rate ratio increased. FIG. 1 shows the relationship between the N concentration in the film and the anisotropic magnetic field Hk. Hk decreased as the N concentration increased and became isotropic when it exceeded 15 atom%. [Comparative Example-2] A film was formed under the same conditions as in Example-2 with the N ₂ addition ratio of the sputtering gas being 10%. The X-ray diffraction pattern of the obtained film is shown in FIG. The composition of the film analyzed by Rutherford backscattering method was Fe ₄₉ Si ₉ O ₁₅ N ₂₆ (atomic%). A broad halo is seen around 40 °, and there are no other peaks, indicating that the structure is amorphous. The DC magnetic hysteresis curve of this film is shown in FIG. The coercive force was 18 Oe and the saturation magnetic field was 252 Oe, which was very large and soft magnetic characteristics could not be obtained. In addition to this film 500
The magnetic properties were not improved by heat treatment in a magnetic field up to ℃.

[0018]

As described above, according to the present invention, it is possible to provide a thin film material which is a soft magnetic thin film having both high electric resistance and high saturation magnetization and excellent high frequency characteristics. The thin film of the present invention has a high resonance frequency because of its large anisotropic magnetic field,
Good characteristics can be maintained up to very high frequencies. Further, since the value of the magnetic permeability does not change up to the anisotropic magnetic field, a constant magnetic permeability characteristic is exhibited and an excellent direct current superposition characteristic can be provided. Furthermore, since the saturation magnetostriction constant is as small as 10 ⁻⁶ , it is possible to reduce the influence of processing strain and the like.
Its industrial significance is great.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between an N concentration in a thin film and an anisotropic magnetic field in an alloy thin film of the present invention.

FIG. 2 is an X-ray diffraction diagram showing a crystal structure of an alloy thin film of the present invention.

FIG. 3 is a bright field image diagram of a transmission electron microscope showing the fine structure of the alloy thin film of the present invention.

FIG. 4 is a characteristic diagram for explaining DC magnetic characteristics of the alloy thin film of the present invention.

FIG. 5 is a characteristic diagram for explaining frequency characteristics of magnetic permeability of the present invention.

FIG. 6 is an X-ray diffraction diagram showing a crystal structure of an alloy thin film.

FIG. 7 is a characteristic diagram showing DC magnetic characteristics of an alloy thin film.

FIG. 8 is an X-ray diffraction diagram showing a crystal structure of an alloy thin film.

FIG. 9 is a characteristic diagram showing DC magnetic characteristics of an alloy thin film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Matsumoto 3-6-6 Minamiyoshinari, Aoba-ku, Sendai-shi, Miyagi Amorphous Electronic Devices Laboratory Co., Ltd. (72) Keian Fujimori Yoshinari, Aoba-ku, Sendai-shi, Miyagi 2-20-3 (72) Inventor Ken Masumoto 3-8-22 Uesugi, Aoba-ku, Sendai-shi, Miyagi (56) Reference JP-A-2-65106 (JP, A) JP-A-3-203307 (JP , A) JP-A-3-132004 (JP, A)

Claims (5)

(57) [Claims] 1. A general formula: Fe _100-xyz M _x N _y L _z
(Atomic%), M is Be, B, Mg, Al, S
i, Ca, Ti, Y, Zr, Mo, In, Sn, Cs,
One or more elements selected from Ba, La, Hf, Ta, Bi, Pb, W, and L is O, F
Is one or two elements selected from among, and the atomic ratio of each is 5 ≦ x ≦ 250 0 ≦ y ≦ 15 15 ≦ z ≦ 35 28 ≦ x + y + z ≦ 50, and its crystal structure is mainly A uniaxial magnetic anisotropic thin film comprising a bcc-Fe structure and an M oxide phase or a fluoride phase. 2. The uniaxial magnetic anisotropic thin film according to claim 1, wherein less than 70% of Fe is replaced with Co. 3. The uniaxial magnetic anisotropic thin film according to claim 1, wherein the film has a network-like fine structure. 4. The uniaxial magnetic anisotropic thin film according to claim 1, wherein the film is crystalline as it is after being formed. 5. The uniaxial magnetic anisotropic thin film according to claim 1, wherein the anisotropic magnetic field of the film is 25 Oe or more.