JPH06120027A - Magnetic artificial lattice film - Google Patents

Abstract

(57) [Summary] [Object] To provide a magnetic artificial lattice film having a high saturation magnetic flux density, an excellent soft magnetic property, and a good high frequency property. A FeCo-based ferromagnetic thin film 2 and an RFeCo-based alloy thin film (R is at least one element selected from the group consisting of Pm, Sm, Er and Tm) or an intermediate layer 3 made of a spinel ferrite magnetic thin film. Stack or
Or Fe-based or FeCo-based ferromagnetic thin film 2 and F
The intermediate layer 3 is made of a NaCl type ionic compound thin film containing at least one element selected from the group consisting of e, Co and Mg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic artificial lattice film used for a plane magnetic element such as a plane inductor, a plane transformer and a thin film magnetic head.

[0002]

2. Description of the Related Art In recent years, miniaturization of various electronic devices has been actively promoted. However, as compared with this, downsizing of the power supply unit constituting the electronic device is delayed. For this reason, the volume ratio of the power supply unit to the entire device is increasing. The miniaturization of electronic equipment is largely due to the LSI of various circuits, but miniaturization and integration of magnetic parts such as inductors and transformers, which are indispensable for the power supply, are delayed, which increases the volume ratio. Is the main cause.

In order to solve this problem, a plane type magnetic element in which a plane coil and a magnetic body are combined has been proposed,
Higher performance is being studied (for example, Shirakawa et al .; Institute of Electrical Engineers of Japan, Magnetics Research Group material, MAG-92-1).
4).

The magnetic thin film used for these magnetic elements is required to have a high magnetic permeability and a high saturation magnetic field in a high frequency region of 1 MHz or more. High saturation magnetization is required to achieve both high permeability and high saturation magnetic field.
Further, such a magnetic thin film has a low loss because it causes a decrease in energy efficiency and operating efficiency of the element itself and an increase in heat generation during operation when the loss increases, and it cannot exhibit sufficient performance. Is required.

In the field of recent magnetic recording technology, the recording density is increasing, the coercive force of the medium is increasing, the energy product is increasing, and the operating frequency is increasing. For example, at the laboratory level, a recording density of 2 Gbits per square inch has been realized (H. Takano et al .;
IEEE Trans. , Magn. , MAG-27,
No. 6, pp. 4678-4683, 1991).

Along with this, magnetic thin films used for magnetic poles of thin film magnetic heads are required to have high saturation magnetic flux density, excellent soft magnetic characteristics (having high magnetic permeability), and excellent frequency characteristics. . These characteristics are generally required for other magnetic elements as well.

At the current state of the art, magnetic materials exhibiting saturation magnetization exceeding 2 Tesla are required. Fe-based and FeCo-based materials are considered to be promising as magnetic materials satisfying such requirements, and are being actively developed. In particular, the FeCo alloy has the highest saturation magnetic flux density among metallic magnetic materials. However, since these materials have a large magnetocrystalline anisotropy K ₁ and a large magnetostriction λs, it is difficult to obtain sufficient soft magnetic characteristics.

FIG. 1 shows the magnetostriction constant λ in the FeCo alloy.
3 shows the composition dependence of s, saturation magnetic flux density Bs, and crystal magnetic anisotropy K ₁ . When Co is 80 at% or more,
The bcc structure becomes unstable, exhibits the fcc structure, and the saturation magnetic flux density decreases. On the other hand, when Co is 5 at% or less, negative magnetostriction is exhibited. In particular, Co is 20-50
At%, the saturation magnetic flux density is large. For example, Fe
_The constants of ₇₀ Co ₃₀ are λs = 45 × 10 ⁻⁶ and K ₁ = 1.
2 × 10 ⁴ (J / m ³ ) and Is = 2.46T.

The reason why it is difficult to obtain sufficient soft magnetic characteristics with these materials will be described in more detail. . The magnetic anisotropy constant K is the sum of the uniaxial magnetic anisotropy constant Ku induced by the stress σ and the crystalline magnetic anisotropy constant K _1, and Ku = 3λs · σ / 2 K = K ₁ + Ku = It is expressed as K ₁ + 3λs · σ / 2.

When the initial permeability is μ _i and the saturation magnetization is Is (T), μ _i ˜Is ² / (3K · μ ₀ ) +1. Therefore, in the case of Fe ₇₀ Co ₃₀ , σ = 2.5
If x10 ⁷ N / m ³ , μ _i becomes a low value of about 100.

On the other hand, in the so-called permendur composition of Fe ₆₀ Co ₄₀ , K ₁ = 0, so it is considered to be advantageous for improving the magnetic permeability. However, the value is actually only about 700. This is because the magnetostriction λs becomes large in the permendur composition.

In the high frequency region, the magnetic permeability is mainly provided by the rotating magnetization process. Therefore, excitation in the hard axis direction becomes important, and high-frequency permeability and high-frequency loss in the hard axis direction become important physical property values. High frequency loss is an amount that is complicatedly associated with various physical properties of a sample. Hysteresis loss and eddy current loss are mentioned as main factors of loss. In case of easy axis excitation on the low frequency side,
Abnormal loss due to domain wall movement may cause a problem. However, in high-frequency excitation mainly in the rotating magnetization process in the direction of the hard axis, abnormal loss can usually be ignored. Therefore, in order to realize high saturation magnetization and high permeability and low loss in the high frequency region of 1 MHz, it is necessary to reduce hysteresis loss and eddy current loss while achieving both high saturation magnetization and soft magnetism.

In recent years, as means for softening these materials, microcrystallization by adding B, N, C or the like, or adding IVA group or VA group element has been attempted. However, when any additive element is used, Fe-based and FeCo
In many cases, the high saturation magnetization inherent in the material of the system is deteriorated.

In order to reduce high frequency eddy current loss,
Attempts have also been made to form a multi-layer with an insulating film such as non-magnetic SiO ₂ or AlN. In this case, the insulating film must be thin in order to subdivide the magnetic domains by magnetostatic coupling between the magnetic films, while the insulating film must be thick to sufficiently block the eddy current generated in the magnetic film. There must be. In practice, an insulating film having an appropriate thickness is formed to subdivide the magnetic domains and block the eddy current, but this is not sufficient to satisfy both requirements.

[0015]

As described above, a soft magnetic thin film material having a high saturation magnetic flux density, excellent soft magnetic characteristics, and good high frequency characteristics is used as a flat inductor, a flat transformer, and a magnetic recording head magnetic pole material. Although requested,
A material satisfying all of these has not been developed yet.

An object of the present invention is to provide a magnetic artificial lattice film which has a high saturation magnetic flux density, an excellent soft magnetic property and a good high frequency property and which can be effectively applied to a planar magnetic element or the like.

[0017]

Means and Actions for Solving the Problems A magnetic artificial lattice film of the first invention of the present application comprises a FeCo-based ferromagnetic thin film and RFe.
A Co-based alloy thin film (R is at least one element selected from the group consisting of Pm, Sm, Er and Tm) is laminated.

The magnetic artificial lattice film of the second invention of the present application is Fe
It is characterized in that a Co type ferromagnetic thin film and a spinel ferrite magnetic thin film are laminated.

The magnetic artificial lattice film of the third invention of the present application is Fe
-Based or FeCo-based ferromagnetic layers and Fe, Co and M
It is characterized in that a NaCl-type ionic compound containing at least one element selected from the group consisting of g is laminated by heteroepitaxy.

The structure of the magnetic artificial lattice film according to the present invention is shown in FIG. As shown in FIG. 2, a ferromagnetic thin film 2, an intermediate layer 3, and a ferromagnetic thin film 2 are sequentially laminated on a substrate 1 to form a magnetic artificial lattice film 4. Although FIG. 2 shows a sandwich structure composed of three layers, it goes without saying that the number of layers may be further increased.

In the present invention, Fe-based or FeCo
A system ferromagnetic thin film is used. In particular, F with Co of 20 to 50 at% is obtained, which can obtain high saturation magnetization of about 2.4 Tesla.
It is preferable to use eCo. The FeCo-based ferromagnetic thin film in this composition range has positive magnetostriction.

The magnetic artificial lattice film of the first and second inventions of the present application comprises an FeCo-based ferromagnetic thin film having a positive magnetostriction and an intermediate layer composed of an RFeCo-based alloy thin film having a negative magnetostriction or a spinel ferrite magnetic thin film. Is laminated, the effective magnetostriction is reduced as the entire film.

RF used in the first invention of the present application
The eCo-based alloy thin film (R is at least one selected from the group consisting of Pm, Sm, Er and Tm) has a large negative saturation magnetostriction constant. For example, in FIG.
shows the relationship between the _{m x (Fe 0.75 Co 0.25)} 100-x Sm content and magnetostriction constant of the alloy. As you can see from this figure,
A large negative magnetostriction constant is exhibited when the Sm content is 5 to 50 at%. In general, regarding the RFeCo alloy, if the R content is too low, the magnetostriction constant becomes a positive value, and if the R content is too high, the saturation magnetization becomes small. Therefore, R
The content of is preferably 10 to 40 at%, more preferably 10 to 30 at% where the magnetostriction constant exhibits a negative extreme value.

The spinel ferrite magnetic thin film used in the second invention of the present application is M _1-x Fe _{2 + X} O ₄ (M is M
g, Mn, Co, Ni, Cu, and at least one metal element selected from the group consisting of Li), and has a large negative magnetostriction and a small magnetocrystalline anisotropy. Table 1 shows examples of typical spinel ferrites having negative polycrystalline magnetostriction. It can be seen from Table 1 that CoNi ferrite has large negative magnetostriction and small magnetocrystalline anisotropy.

[0025]

[Table 1] In the first and second inventions of the present application, the thickness of the FeCo-based ferromagnetic thin film is preferably sufficiently thinner than the skin depth at the excitation frequency used. The FeCo alloy has a resistivity of about 20 μΩ · cm and a relative permeability μ _s of 100.
When it is about 0, the skin depth s is expressed as s = (2ρ / ωμ ₀ · _μs ) ^1/2 = 7100 / f ^1/2 (μm). When the frequency f is 200 MHz, s = 0.
It becomes 5 μm. Therefore, as a guide, the film thickness of the FeCo film may be set to 0.5 μm or less. However, if the thickness of one layer of the ferromagnetic film is large, the crystal grain size becomes large, and the influence of the crystal magnetic anisotropy K ₁ cannot be ignored. Therefore, in FIG. 1, it is preferable to select a composition in which K _{1 is} almost zero.

Further, a ferromagnetic film having a film thickness t ₁ (magnetostriction constant λs
₁ , the induced magnetic anisotropy constant Ku ₁ ) and the intermediate layer (the magnetostriction constant λs ₂ , the induced magnetic anisotropy constant Ku ₂ ) having the film thickness t ₂ are laminated, and the effective magnetostriction constant λs _eff is as follows. It is expressed as.

[0027]

[Equation 1] The absolute value of this effective magnetostriction constant λs _eff is preferably less than 2 × 10 ⁻⁶ . Similarly, the effective induced magnetic anisotropy constant Ku _eff is expressed as follows.

[0028]

[Equation 2] From these equations, the relationship of the film thickness between the ferromagnetic film and the intermediate layer is t ₂ / t ₁ = −λs ₁ / λs ₂ = −Ku ₁ / Ku ₂ . If the thickness of each ferromagnetic film and the intermediate layer is defined as the stacking period, if the stacking period is too small, the crystal structure of the film is disturbed and sufficient soft magnetism cannot be obtained.
On the other hand, if the lamination period is too large, sufficient soft magnetism cannot be obtained due to the internal stress of each film. Therefore, the stacking period is preferably in the range of 5 to 1000 nm, and 1
The range of 0 to 500 nm is more preferable. If the above conditions are satisfied, not only the effective magnetostriction constant of the film as a whole can be lowered, but also the crystal magnetic anisotropy can be reduced, so that the magnetic permeability can be made extremely high.

Further, the effective saturation magnetic flux density Bs
_eff is expressed as follows.

[0030]

[Equation 3] FIG. 4 shows the relationship between the composition in which the magnetostriction becomes zero and the saturation magnetic flux density when the FeCo film and various ferrite films are laminated. For example, Fe having a composition in the range shown by the arrow in FIG.
When a Co film is used, K ₁ is close to 0, but since the magnetostriction is large, it is necessary to increase the thickness of the ferrite film.
However, the FeCo film in this composition range is still 2.
Since it has a high saturation magnetic flux density of 4 T or higher, an effective saturation magnetic flux density of 1.5 T or higher can be obtained even by stacking layers.

In the first invention of the present application, RFeC
When the o film is amorphous, FeCo film and RFeCo film
Mutual diffusion with the film is suppressed and the specific resistance is increased, so that improvement of soft magnetism can be expected.

Further, since the ferrite film used in the second invention of the present application has a high resistivity, it is effective in reducing the eddy current loss and can be expected to improve the high frequency characteristics.

Furthermore, in the first and second inventions of the present application, uniaxial anisotropy can be easily imparted to the entire film by heat treatment in a magnetic field.

The third invention of the present application is based on Fe or FeCo.
By epitaxially growing the ferromagnetic film of the system,
The crystal symmetry and lattice constant are greatly changed from those of the bulk. The symmetry referred to here is, for example, the number of in-plane easy magnetization axes or relative orientations, that is, uniaxial anisotropy, biaxial anisotropy, and the like. For example, it is possible to change the effective magnetic anisotropy energy in the film plane significantly by the effect of inverse magnetostriction by introducing strain to the crystal lattice, which is advantageous for high-frequency excitation in the hard axis direction. is there.

In the third invention of the present application, the substrate is
NaCl-type ionic compounds such as MgO, CuZn, P
A metal such as t and a perovskite type oxide such as SrTiO ₃ can be used. N used as an intermediate layer
Examples of the aCl-type ionic compound include FeO, CoO, and M
Examples thereof include gO and Fe _1-xy Co _x Mg _y O. The crystal structure of the Fe-based or FeCo-based ferromagnetic film grown by heteroepitaxy on these substrates or intermediate layers is a body-centered cubic lattice bcc or a body-centered cubic lattice bct in which the body-centered cubic lattice is distorted to some extent. .

FIG. 5 schematically shows the surface structure of the MgO (100) plane, FIG. 6 shows the surface structure of the Fe (100) plane, and FIG. 7 shows the state in which these planes are superposed. The lattice constants of NaCl-type ionic compounds known in bulk are as follows. MgO: 4.21 Å, FeO:
It is 4.31 angstroms and CoO: 4.26 angstroms. On the other hand, bulk bccFeCo has a lattice constant close to that of bulk bccFe (2.87 angstrom). As described above, the NaCl-type ionic compound is likely to be epitaxially grown with the Fe-based or FeCo-based body-centered lattice. Therefore, the relationship in FIG.
The same applies to other combinations.
Of course, in the third invention of the present application, a heteroepitaxy relationship other than the above may be applied.

Further, since Mg is difficult to form a solid solution with Fe or FeCo and Fe and Co do not become impurities with respect to Fe or FeCo, the saturation magnetization of the Fe-based or FeCo-based magnetic layer is not impaired. Moreover, in general, the properties of the magnetic material largely depend on the crystal structure. In particular, in the Fe system, the magnetic moment may increase due to an increase in the unit cell volume due to the magnetic volume effect or the like.
For example, if a non-equilibrium phase different from the bulk is realized by utilizing epitaxial growth, a high saturation magnetization of 3 Tesla class can be obtained. In this case, addition of an element to the magnetic film may be used in combination to replace a part of the body-centered lattice with an element other than Fe or Co or to inject another element into an appropriate interstitial position.

The lattice constant of the Fe-based or FeCo-based magnetic film is preferably 2.8 to 3.1 angstrom. When the lattice constant exceeds 3.1 angstrom, the body-centered crystal lattice can be maintained, and even if the magnetic moment per unit atom exceeds the bulk value, the magnetic moment per unit volume decreases due to the increase in unit cell volume. However, it is not preferable because high saturation magnetization may not be obtained.

First, when a Fe-based or FeCo-based magnetic film is epitaxially grown on the substrate, it is preferable that the (nmm) plane of the magnetic film be parallel to the substrate surface. Here, n ≠ 0, m, and m ≠ 0.

In order to increase the magnetic permeability due to the rotating magnetization process, it is preferable that the change in magnetic energy is small in the plane in which the magnetic moment rotates during excitation, and as long as the change is possible, it is monotonous and reversible. If the specific crystal plane of the magnetic film is parallel to the substrate plane, the change in magnetic energy in the plane where the magnetic moment rotates will be small. The reason will be described.

The cubic crystal magnetic anisotropy Ea is represented by the following equation.

Ea = K ₁ (α ₁ ² α ₂ ² + α ₂ ² α ₃ ² + α ₃ ² α ₁ ² ) In the formula, K ₁ is a cubic crystal magnetic anisotropy constant, and α is a direction cosine with respect to each crystal axis. is there. Higher-order terms are omitted in this equation. Describing convenience K ₁ in the following description as a positive is, K ₁ can of course may be negative. Further, K ₁ may include a term of magnetoelastic energy due to spontaneous strain due to magnetostriction and a term of magnetoelastic energy due to magnetostriction due to stress.

When n = m, the (nmm) plane is (111)
It becomes a plane equivalent to the plane, and has threefold symmetry in the film plane. m =
When 0 and n ≠ 0, the (nmm) plane becomes a plane equivalent to the (100) plane, and has 4-fold symmetry in the film plane. Other (nm
All the m) planes are twice symmetrical. Therefore, n of the magnetic film
If the (nmm) plane satisfying ≠ m and m ≠ 0 is parallel to the substrate plane, uniaxial magnetic anisotropy can be introduced in the film plane.

On a (nmm) plane satisfying n ≠ m and m ≠ 0, the <0, -1, -1> direction and <
2m, -n, -n> directions exist. In these axial directions, K ₁ is the direction in which the value takes an extreme value, one of which is the easy magnetization axis direction and the other is the hard magnetization axis direction.

N ≠ m and m ≠ 0 are satisfied, and n = 0.
The (nmm) plane satisfying the above condition is a plane equivalent to the (011) plane. This surface is a general orientation surface in bcc Fe-based or FeCo-based. However, as shown below, n ≠
In the (011) plane of the (nmm) planes that satisfy m and m ≠ 0, the <2m, −n, −n> direction and <0, −1, −1>
The difference in magnetic anisotropy energy from the direction becomes the largest.
This means that the in-plane uniaxial magnetic anisotropy energy and the anisotropic magnetic field increase. Therefore, it is not preferable to increase the magnetic permeability due to the rotating magnetization process in the hard axis direction.

Here, for the (nmm) plane, n is normalized by m and expressed as (n / m, 1, 1) plane, and <2 in the plane
The difference ΔEa of the magnetic anisotropy energy due to K ₁ between the −n / m, −n / m> direction and the <0, 1, −1> direction is K ₁
Standardize and examine its size. FIG. 8 shows the relationship between n / m and ΔEa / K ₁ . In this figure, n
In the case of / m = 1, the surface is equivalent to the (111) surface described above and is not the subject of the discussion here. As is apparent from FIG. 8, comparing the absolute value of ΔEa / K _{1 in} the case of n / m = 0 (that is, n = 0) and in other cases, for example, n / m = 2, the former is about the same as the latter. A very large value of 3 times is shown. Thus, the surface of n / m = 0 is inconvenient for increasing the magnetic permeability.

Based on the above discussion, it is expected that the frequency dependence of the magnetic permeability in high frequency excitation is schematically shown in FIG. In this figure, n / m in FIG.
The changes in magnetic permeability are shown for the = 0, 1, 2 planes and the (001) plane. Here, the values of K ₁ are all common, and it is assumed that the film thickness of the sample is sufficiently thin so that the eddy current loss can be ignored. Further, it is assumed that the direction of the applied magnetic field is set parallel to the film surface and is set in a direction suitable for high frequency excitation in each sample.

For the n / m = 1 plane and the (001) plane,
Since the in-plane anisotropy is not uniaxial, the entire film cannot be excited by the hard axis, and no matter what direction the high-frequency magnetic field is applied in the film plane, a rotating magnetization process occurs in a part of the magnetic film. Only. For this reason, in the high frequency region, the magnetization process due to the domain wall movement cannot follow, and high magnetic permeability cannot be obtained. In addition, in the plane of n / m = 1, K ₁
Since it does not contribute to the in-plane anisotropy, it is often dominated by higher-order anisotropy or exhibits a complicated magnetic domain structure.

In the planes of n / m = 0 and 2, uniaxial magnetic anisotropy is obtained, and the hard magnetization excitation causes a rotating magnetization process in the entire film. However, as described above, the uniaxial anisotropy energy is large on the surface of n / m = 0 and the anisotropic magnetic field is large, so that the high-frequency magnetic permeability is about 1/3 of that of the surface of n / m = 2. I can only get it. After all, in the example of FIG. 9, n / m =
In the case of 2, that is, the plane equivalent to the (211) plane shows the highest high frequency magnetic permeability. In the case where uniaxial anisotropy can be realized in the film plane without being disturbed by other magnetic anisotropy in the plane where n / m is larger than 2, as shown in FIG. It becomes small, and due to this, high magnetic permeability is obtained.

Strictly speaking, the above discussion relates to a cubic crystal, but it can be established even if the cubic crystal is distorted due to the epitaxial growth mechanism and the effect of the additional element. In particular, in a tetragonal system, when the index on the c-axis is n and the index on the a-axis corresponds to two m, the symmetry conditions are exactly the same as above.

However, in order to reduce the loss when a single-layer magnetic film is used, it is conceivable to reduce the film thickness.
This is actually difficult. For example, in a planar magnetic element represented by a planar inductor, the total amount of magnetic flux that the magnetic film should bear in order to obtain a predetermined performance is specified. Therefore, even if the magnetic flux density is maintained at a relatively high level, the cross-sectional area of the film cannot be reduced so much.
Therefore, the total film thickness cannot be made too thin, and there is a limit to reduction of loss.

In the third invention of the present application, an intermediate layer made of a NaCl-type ionic compound and a magnetic film are sequentially laminated by heteroepitaxy, and the crystal growth plane and the lattice constant are controlled over the entire film. Fe, Co and M
If an NaCl-type ionic compound containing at least one element selected from the group consisting of g is used, heteroepitaxy with the Fe-based or FeCo-based magnetic film can be realized as described above. The composition of the NaCl-type ionic compound may be deviated from the stoichiometric ratio.
Rather, the composition may be intentionally deviated from the stoichiometric ratio in order to control the lattice constant.

Even in the magnetic film laminated with the intermediate layer made of NaCl-type ionic compound, the magnetic film satisfies n ≠ 0, m and m ≠ 0 with respect to the substrate surface or the film surface (nmm). It is preferred that the planes be parallel.
For example, as described above, in order to drive the entire artificial lattice film with a uniform alternating magnetic field at a high frequency, it is appropriate to give uniaxial anisotropy and excite in the hard magnetization axis direction.
1) It is preferable to grow a plane or the like. However, even when the (100) plane of the magnetic film is parallel to the substrate surface or the film surface and the film has biaxial anisotropy, the entire film is processed into an appropriate shape and only in the hard axis direction. If it is excited, the desired effect can be obtained.

In the magnetic artificial lattice film of the third invention of the present application, the magnetic anisotropy and the saturation magnetization of the magnetic film can be positively controlled by the means described above, and the magnetic suitable for the target magnetic element. The characteristics can be obtained. By adopting the laminated structure in which the intermediate layer is interposed between the magnetic layers in this way, the thickness of the unit magnetic layer can be made thinner than the skin depth, so that the high frequency loss can be significantly reduced as compared with the case of using a single layer film. Can be suppressed.

In the present invention, the method for forming the magnetic film is not particularly limited, and the RF sputtering method, the ion beam sputtering method, the vacuum evaporation method, MBE, CVD, sol-
A gel method or the like can be used. Further, in the case of forming a NaCl type ionic compound into a film, oxygen may be supplied at an appropriate partial pressure during the film formation by the above method.

[0056]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 An example of producing an artificial lattice film in which FeCo films and SmFeCo films are alternately laminated on a glass substrate will be described.

In this example, a normal sputtering apparatus was used to perform sputtering under the following conditions.

A: FeCo film formation Target: Fe Co Ar Gas pressure: 0.67 Pa Output: Fe; DC magnetron sputtering, 2.5
A Co; DC magnetron sputter, 1.42 A Substrate temperature: room temperature The composition of the FeCo film under these conditions is Fe _60.9 Co _39.1 (a
t%), and the film formation rate was 23 nm / min. Under this condition, a FeCo film having a film thickness of 20 nm was formed.

B: SmFeCo film formation Target: Fe Co Sm Ar Gas pressure: 0.67 Pa Output: Fe; DC magnetron sputtering, 2.5
A Co; DC magnetron sputter, 1.42 A Sm; RF magnetron sputter, 178 W Substrate temperature: room temperature The composition of the SmFeCo film under these conditions is Sm _9.9 Fe _53.6
Co _36.5 (at%), and the film formation rate was 28 nm / min. Under this condition, a SmFeCo film having a film thickness of 6.8 nm was formed.

The above steps A and B are alternately repeated eight times, and as shown in FIG. 10, a total film thickness of eight FeCo films 12 and eight SmFeCo films 13 alternately laminated on the glass substrate 11. 214nm artificial lattice film 1
4 was formed. FeCo forming the artificial lattice film 14
The physical properties of the film and the SmFeCo film are as follows.

FeCo film Saturation magnetic flux density Is = 2.2T Saturation magnetostriction λs = 51 × 10 ⁻⁶ Coercive force Hc = 6400 A / m SmFeCo film Saturation magnetic flux density Is = 1.4T Saturation magnetostriction λs = −150 × 10 ⁻⁶ Magnetic force Hc = 28800 A / m The calculation result of the equation (1) is as follows.

| (51 × 20-150 × 6.8) / (20 + 6.8) | × 10 ^-6 = 0 The physical properties of the obtained artificial lattice films were as follows.

Saturation magnetic flux density Is = 2.0T Saturation magnetostriction λs <10 ⁻⁶ Coercive force Hc = 5920 A / m This film was subjected to 3 × 250 ° C. in a DC magnetic field of 8 × 10 ⁴ A / m.
The physical properties of the artificial lattice film obtained by heat treatment for 0 minutes were as follows.

Saturation magnetic flux density Is = 2.1T Saturation magnetostriction λs <10 ⁻⁶ Coercive force in the hard axis direction Hc = 600 A / m As described above, a high saturation magnetic flux density of 2.1T and 1
Artificial lattice film having 0 ^-6 low saturation magnetostriction was obtained.

Example 2 Another example of producing an artificial lattice film in which FeCo films and SmFeCo films are alternately laminated on a glass substrate will be described.

In this example, a normal sputtering apparatus was used to carry out sputtering under the following conditions.

A: Film formation of FeCo Same as in Example 1.

B: Film formation of SmFeCo Target: Fe Co Sm Ar Gas pressure: 0.67 Pa Output: Fe; DC magnetron sputtering, 2.5
A Co; DC magnetron sputter, 1.42 A Sm; RF magnetron sputter, 283 W Substrate temperature: room temperature The composition of the SmFeCo film under these conditions is Sm _15.7 Fe _48.4
Co _35.9 (at%), and the film formation rate was 32 nm / min. Under this condition, a SmFeCo film having a film thickness of 4.0 nm was formed.

The above steps A and B are alternately repeated 9 times, and as shown in FIG. 11, a total film thickness of 9 layers of FeCo films 12 and SmFeCo films 13 alternately laminated on the glass substrate 11. 216nm artificial lattice film 1
5 was formed. FeCo forming the artificial lattice film 15
The physical properties of the film and the SmFeCo film are as follows.

FeCo film Same as in Example 1.

SmFeCo film Saturation magnetic flux density Is = 1.1T Saturation magnetostriction λs = −250 × 10 ⁻⁶ Coercive force Hc = 55000 A / m The calculation result of the equation (1) is as follows.

| (51 × 20−250 × 4) / (20 + 4) | × 10 ⁻⁶ = 0.8 × 10 ⁻⁶ The physical properties of the obtained artificial lattice film were as follows.

Saturation magnetic flux density Is = 2.0T Saturation magnetostriction λs <10 ⁻⁶ Coercive force Hc = 4400 A / m This film was subjected to 3 × 350 ° C. in a direct current magnetic field of 8 × 10 ⁴ A / m.
The physical properties of the artificial lattice film obtained by heat treatment for 0 minutes were as follows.

Saturation magnetic flux density Is = 2.1T Saturation magnetostriction λs <10 ⁻⁶ Coercive force Hc = 472 A / m in the hard axis direction As described above, a high saturation magnetic flux density of 2.1T and 1
Artificial lattice film having 0 ^-6 low saturation magnetostriction was obtained.

Example 3 An example in which an artificial lattice film in which a FeCo film and a spinel ferrite film were alternately laminated on a glass substrate was produced will be described.

In this example, a normal RF sputtering apparatus was used to carry out sputtering under the following conditions.

A: FeCo film formation Target: Fe ₆₀ Co ₄₀ (at%) alloy Sputtering gas: Ar Total pressure: 0.3 Pa RF power density: 4 W / cm ² Under these conditions, Fe ₆₀ Co ₄₀ with a film thickness of 100 nm is formed. A film was formed.

B: Film formation of spinel ferrite Target: Co _0.05 Ni _0.95 Fe ₂ O ₄ sintered body Sputtering gas: Mixed gas of Ar and O ₂ (concentration 10%) Total pressure: 0.3 Pa RF power density: 4 W / Cm ² Under these conditions, the film thickness of Co _0.05 Ni _0.95 Fe ₂ O ₄ is 10
The film was formed by changing the thickness in the range of up to 200 nm.

The above steps A and B are alternately repeated four times, and as shown in FIG. 12, a Fe ₆₀ Co ₄₀ film 22 and a Co _0.05 Ni _0.95 Fe ₂ film are formed on the glass substrate 21.
Artificial lattice film 24 in which four O ₄ films 23 are alternately laminated
Was formed. Each layer of the artificial lattice film 24 was polycrystalline. According to the cross-sectional TEM observation, the average crystal grain size of the FeCo layer was about 30 nm, and the average crystal grain size of the ferrite layer was almost equal to the film thickness.

FIG. 13 shows the film thickness of the ferrite layer and 10 MH.
The relationship between the initial magnetic permeability μ _i and the saturation magnetic flux density Bs at z is shown. As is clear from this figure, the initial magnetic permeability becomes maximum when the thickness of the ferrite layer is around 90 nm, and the initial magnetic permeability becomes 3600.
It shows a high value. Thus, comparing with the FeCo single layer film, which can obtain only the initial magnetic permeability of about 700,
With the artificial lattice film of this embodiment, a maximum initial permeability of about 5 times can be obtained.

Further, regarding the artificial lattice film in which Fe ₆₀ Co ₄₀ having a film thickness of 100 nm and Co _0.05 Ni _0.95 Fe ₂ O ₄ having a film thickness of 120 nm were alternately laminated, the frequency characteristic of the initial magnetic permeability was measured by the figure 8 coil method. It was measured up to 100 MHz. As a result, the initial permeability at 100 MHz is still 10
It was found that it has a value of 00 or more and is excellent in high frequency characteristics.

Next, using the artificial lattice film of this example as the upper and lower magnetic bodies, the planar inductor shown in FIG. 14 was produced. In FIG. 14, on the glass substrate 21,
The artificial lattice film 24, the insulating film 25 made of SiO ₂ , the planar spiral coil 26, the insulating film 25 made of SiO ₂ , and the artificial lattice film 24 are sequentially laminated.

For this planar inductor, 10 MHz
As a result of investigating the characteristics in, the inductance is 5 μH,
The quality factor was 15, and an efficiency of 90% or more was obtained.

Further, when this planar inductor was applied to a 3 MHz output 10 MHz switching DC-DC converter shown in FIG. 15, normal operation was confirmed.

Example 4 FeC was formed on the surface of a silicon substrate through a thermally oxidized SiO ₂ film.
An example of producing an artificial lattice film in which an o film and a spinel ferrite film are alternately laminated will be described.

In this example, an ion beam sputtering apparatus having two Kaufman ion guns was used and sputtering was performed under the following conditions. The substrate can be heated by an infrared heater. In addition, a uniaxial DC magnetic field of 200 Oe was applied to the substrate surface by a permanent magnet provided in the substrate holder, and uniaxial magnetic anisotropy was imparted to the magnetic film by film formation in the magnetic field.

A: FeCo film formation Target: Fe ₈₀ Co ₂₀ (at%) alloy Sputtering gas: Ar Acceleration energy: 500 eV Substrate temperature: 300 ° C. A Fe ₈₀ Co ₂₀ film having a film thickness of 10 nm was formed under these conditions.

B: Ferrite film formation target: Co _0.1 Ni _0.9 Fe ₂ O ₄ sintered body Sputtering gas: Ar Acceleration energy: 1 keV Substrate temperature: 300 ° C. Note that in order to prevent target charge-up during ferrite film formation. Was irradiated with an electron beam and oxygen gas of 0.5 Pa was supplied near the substrate to form a film in a reactive atmosphere. Under this condition, Co _0.1
A film of Ni _0.9 Fe ₂ O ₄ was formed.

The above-described steps A and B are alternately repeated 70 times, and as shown in FIG.
On the SiO ₂ film 32 having a film thickness of 1 μm formed thereon, a Fe ₈₀ Co ₂₀ film 33 having a film thickness of 10 nm and a Co _0.1 Ni _0.9 Fe ₂ O ₄ 34 film having a film thickness of 4.5 nm are alternately laminated 70 layers each. An artificial lattice film 35 having a total film thickness of about 1 μm was formed. The crystal grain size of each layer of the artificial lattice film 35 was not more than the film thickness.

With respect to this artificial lattice film, the saturation magnetic flux density was 1.8 T and the initial magnetic permeability was 1000. Fe ₈₀ Co
Compared with the crystal magnetic anisotropy of ₂₀ single layer film reaching 2 × 10 ⁴ (J / m ³ ), and the initial magnetic permeability estimated from this is only several tens, this initial magnetic permeability is a very large value. Is. This is due to the fact that the ferrite acts as a barrier as well as the reduction of magnetostriction due to the lamination with ferrite.
It is considered that the suppression of eCo crystal grain growth (so-called microcrystal effect) contributes. It was confirmed that the initial permeability when this artificial lattice film was excited by the hard axis was almost flat up to 100 MHz, and the frequency characteristics were excellent.

The heat treatment temperature dependence of the magnetic properties of this artificial lattice film was examined up to 500 ° C. As a result, it was shown that the characteristics were almost the same as those immediately after the film formation and the heat resistance was excellent. The magnetic film after heat treatment at 500 ° C. was subjected to elemental analysis in the depth direction by AES. As a result, a mutual reaction layer was confirmed at the interface between the FeCo layer and the ferrite layer, but its thickness was estimated to be about 1 nm, and it was confirmed that the influence on the whole was small. Due to such excellent heat resistance, the influence of thermal history due to the manufacturing process of the magnetic device is minor.

Reference Example An example in which the present inventors independently investigated the uniaxial magnetic anisotropy in the film plane of the FeCo single layer film formed on the MgO (110) single crystal substrate or the MgO (100) single crystal substrate. Will be described.

In the ion beam sputtering apparatus, M
A gO (110) single crystal substrate and a Fe ₇₅ Co ₂₅ alloy target were set and pre-evacuated. Vacuum degree is 3 × 10 ^-7 T
After reaching orr, target pre-sputtering and substrate pre-sputtering were sequentially performed as pretreatment. Next, sputtering was performed under the following conditions.

Substrate temperature: room temperature (not controlled) Sputtering gas: Ar Vacuum degree during film formation: 1.4 × 10 ⁻⁴ (Torr) Ion beam acceleration voltage Va: 600 (V) An FeCo thin film having a thickness of 0.1 μm was formed. After film formation, heat treatment was performed in vacuum at 290 ° C. in a non-magnetic field.

When the composition of the thin film was measured by ICP emission spectrometry, it was Fe ₇₂ Co ₂₈ . The crystal structure and orientation of the thin film were determined by X-ray diffraction using CuKα rays and reflection high-energy electron diffraction (RHEED, electron beam accelerating voltage: 100).
It was analyzed by kV). As a result, the crystal structure of the thin film is b
It was confirmed that the cc phase was achieved and epitaxial growth was realized. The orientation relationship between the substrate and the FeCo thin film was as follows. This is n / m in FIG. 8 described above.
This corresponds to the case of = 2.

Surface: (211) bccFeCo // (110) MgO Axis: <111> bccFeCo // <110> MgO It was formed into a disk shape having a diameter of about 4.7 mm. This is to remove the influence of the shape magnetic anisotropy.

The magnetization curve in the film plane was measured using a vibrating sample magnetometer. FIG. 17 shows the magnetization curve of the as-deposited film, and FIG. 18 shows the magnetization curve of the film after heat treatment. As shown in FIG. 17, in the film not subjected to the heat treatment, <-
1,1,1> was the easy axis, and <0,1, -1> was the difficult axis. This is the value of the bulk magnetic anisotropy constant (reference value K
₁ = + (3 + δ) × 10 ⁵ erg / cm ³ ), which is different from the direction of the easy axis expected by 90 °, and shows the magnetic anisotropy peculiar to the epitaxial film. As shown in FIG. 18, in the film after the heat treatment, <-1,1,1> was the difficult axis and <0,1, -1> was the easy axis.

The saturation magnetization Is was 2.4T. This value almost agrees with the value of the bulk of the same composition. The coercive force in the hard axis direction was 0.9 Oe. In these samples, it is considered that the magnetoelastic energy due to the stress introduced by the epitaxial growth contributes to the direction of reducing the coercive force.

Also, using a thin film magnetic torque meter, 10 kO
The external magnetic field of e was applied while rotating in the film plane, and the magnetic torque curve was measured. FIG. 19 shows the magnetic torque curve of the as-deposited film, and FIG. 20 shows the magnetic torque curve of the film after heat treatment.

The obtained magnetic torque curve was Fourier-transformed and analyzed to obtain the amount of change in the magnetic anisotropy energy Ea due to the change in the orientation of the saturation magnetization vector Is. Ea is
It was calculated by analytically integrating the torque amplitude value of each order obtained by Fourier transforming the magnetic torque curve. The calculated difference ΔEa in magnetic anisotropy energy between the easy axis direction and the hard axis direction was 1.9 × 10 ⁵ erg / cm ³ . The value of ΔEa is larger than the value expected from the bulk anisotropy constant, but this is due to the contribution of the inverse magnetostriction effect due to the anisotropic lattice strain peculiar to the epitaxial thin film and the slip induced magnetic anisotropy. It is estimated that As described above, when the (011) plane is parallel to the substrate surface, a larger ΔEa is considered to occur. Thus, the effect of obtaining in-plane uniaxial magnetic anisotropy suitable for high frequency excitation in the (nmm) plane was confirmed.

Next, an Fe ₇₂ Co ₂₈ film was formed by the same method and conditions as described above, except that the MgO (100) single crystal substrate was used instead of the MgO (110) single crystal substrate. The same analysis as above confirmed that the epitaxial growth of bccFe ₇₂ Co ₂₈ was realized. The orientation relationship between the substrate and the FeCo thin film was as follows.

Surface: (100) bccFeCo // (100) MgO Axis: <110> bccFeCo // <100> MgO <100> bccFeCo // <110> MgO This is when m = 0 with respect to the substrate surface. This is equivalent to the case where a plane equivalent to the (nmm) plane of, ie, the (100) plane is parallel. The value of the saturation magnetization was 2.4T. FIG. 21 shows the magnetic torque curve for this film. As is clear from this figure, in the case of a film in which the plane equivalent to the (100) plane is parallel to the substrate plane, two directions orthogonal to each other are easy magnetization axes. Therefore, uniaxial anisotropy cannot be obtained in the film plane, which is not suitable for magnetization hard axis excitation.

However, it will be shown below that even a FeCo film whose (211) plane is parallel to the substrate surface cannot always obtain good high frequency characteristics with a single layer film. MgO (110)
A FeCo thin film with a thickness of 1.2 μm was formed on the single crystal substrate under the same conditions as above for 280 minutes. The composition, saturation magnetization, and coercive force of this sample were almost the same as the above-mentioned values.

FIG. 22 shows the relationship between the excitation frequency and the magnetic permeability of this sample when it was excited at a high frequency in the hard axis direction.
Shown in. As is clear from FIG. 22, a high magnetic permeability is obtained on the low frequency side, but the magnetic permeability sharply decreases in the high frequency region where the excitation frequency exceeds 1 MHz. this is,
It is thought that this is because the eddy current loss increased due to the low resistivity of the FeCo single layer film. As described above, good high frequency characteristics cannot be obtained with a thick FeCo single layer film.

Example 5 An example in which FeCo epitaxial films and FeCoO epitaxial films are alternately laminated on a MgO (110) single crystal substrate will be described.

In the ion beam sputtering apparatus, M
A gO (110) single crystal substrate and a Fe ₇₅ Co ₂₅ alloy target were set and pre-evacuated. Vacuum degree is 3 × 10 ^-7 T
After reaching orr, target pre-sputtering and substrate pre-sputtering were sequentially performed as pretreatment. Next, a laminated film was formed by the following steps.

A: FeCo film formation Substrate temperature: room temperature (not controlled) Sputtering gas: Ar Vacuum degree during film formation: 1.4 × 10 ⁻⁴ (Torr) Ion beam acceleration voltage Va: 600 (V) or more Film formation was performed for 40 minutes under the conditions to form a FeCo film having a film thickness of 172 nm.

B: Film formation of FeCoO (1) Oxygen is caused to flow in the vicinity of the substrate to maintain the pressure at 10 ⁻⁵ Torr and left for 2 minutes to oxidize the FeCo film surface. (2) The FeCo film is formed by opening the shutter for 2.6 seconds under the same conditions as in A. These treatments (1) and (2) were continuously repeated 14 times. As a result, a FeCoO film having a thickness of 4.2 nm was formed.

The above steps A and B were alternately repeated 6 times, and finally step A was performed once. In this way
As shown in FIG. 23, the FeCo film 4 is formed on the MgO substrate 41.
An artificial lattice film 44 in which 2 and FeCoO films 43 were alternately laminated was formed. Regarding the artificial lattice film 44, the plane orientation relationship between the substrate, the FeCo film and the FeCoO film was as follows.

(211) bccFeCo // (110) MgO (211) bccFeCo // (110) FeCoO The magnetization curve of this sample measured by a vibrating sample magnetometer is shown in FIG. 2.3 for the total volume of the laminated film
It showed a high saturation magnetization of 5T. Further, with respect to this sample, when the high frequency excitation was performed in the <0, 1, -1> direction (hard magnetization axis direction) in the bccFeCo (211) plane parallel to the substrate surface, the excitation frequency and the relative permeability were shown. Figure 2
5 shows. As shown in FIG. 25, the high magnetic permeability was maintained even in the high frequency region.

When this sample was heat-treated in vacuum at 290 ° C. in a non-magnetic field, the easy axis and the hard axis were rotated by 90 ° in the plane of the thin film, and the <-1,1,1> direction was the hard axis. Became. When this sample was subjected to high frequency excitation in the <-1,1,1> direction, excellent high frequency characteristics similar to those shown in FIG. 25 were obtained.

Example 6 Instead of the MgO (110) single crystal substrate as the substrate, Mg was used.
An artificial lattice film 44 'having the structure shown in FIG. 23 was formed in exactly the same manner as in Example 5 except that the O (100) single crystal substrate 41' was used. About this sample, substrate, F
The plane orientation relationship between the eCo film and the FeCoO film was as follows.

(100) bccFeCo // (100) MgO (100) bccFeCo // (100) FeCoO The saturation magnetization of this sample was measured and found to be 2.3.
A high saturation magnetization of T or higher was obtained.

Next, a portion of the artificial lattice film 44 'of this sample is wet-etched to prepare a strip-shaped sample as shown in FIG. 26 or a frame-shaped sample as shown in FIG. did. All of these samples were processed so that, of the two easy axes of magnetization perpendicular to each other, the <001> direction was the vertical direction in the drawing and the <010> direction was the horizontal direction in the drawing.

In the sample of FIG. 26, magnetic domains can be stably aligned in one easy axis direction of magnetization. This sample has a structure suitable for a thin film inductor using a rectangular spiral coil. The sample in FIG. 27 has a structure suitable for a thin film inductor using a square spiral coil.

FIG. 28 shows the relationship between the excitation frequency and the relative permeability when these samples were subjected to high frequency excitation in the hard axis direction. The excitation direction was <010>, that is, the lateral direction in the figure. As shown in FIG. 28, in the case of Example 5 (see FIG.
The same excellent high frequency characteristics as in 5) were obtained. However, the magnetic permeability of the frame type sample was about 1/2 of that of the strip type sample. This is because the frame type sample has a domain excited in the direction of the easy axis of magnetization and does not contribute to high frequency excitation. When the frame-shaped sample of FIG. 27 is applied as a magnetic thin film of a thin film inductor that actually uses a square spiral coil, almost the entire area of the artificial lattice film can be excited by the hard axis, so that it is equivalent to the strip sample. It can be expected that the magnetic permeability of is obtained.

Comparative Example 1 An artificial lattice film having a structure shown in FIG. 23 was produced by substantially the same operation using the same apparatus as in Example 5 except that an amorphous SiO ₂ film was formed instead of the FeCoO film. . The amorphous SiO ₂ film is formed of SiO ₂
The target was formed by ion beam sputtering.

With respect to this sample, the orientation relationship between the MgO (110) single crystal substrate and the first layer bccFeCo film was the same as in Example 1. However, bccF after the second layer
Epitaxial growth was not realized in the eCo film, and a polycrystalline film in which the (110) plane was oriented parallel to the substrate surface was obtained.

For this sample, the first layer bccFeC
The results of measuring the magnetization curve by applying a magnetic field in the <-1,1,1> direction and the <0,1, -1> direction of the o film are shown in FIGS. As is clear from these figures, since the coercive force is high in this sample regardless of the direction of excitation, practical magnetic permeability cannot be obtained unless a large amplitude magnetic field sufficiently larger than the coercive force is applied, It is difficult to obtain excellent soft magnetism. Therefore, it is not suitable for various thin film magnetic elements represented by thin film inductors.

[0121]

As described above in detail, according to the present invention, it is possible to provide a magnetic artificial lattice film having a high saturation magnetic flux density and soft magnetism suitable for high frequency excitation, and to provide a high output plane inductor, a plane transformer, and A magnetic recording head most suitable for high-density magnetic recording can be realized.

[Brief description of drawings]

FIG. 1 shows the composition and saturation magnetostriction constant λ of a FeCo film.
s, the magnetocrystalline anisotropy constant K ₁ , and the saturation magnetic flux density Bs
The characteristic view showing the relationship with.

FIG. 2 is a cross-sectional view showing a magnetic artificial lattice film according to the present invention.

FIG. 3 S in Sm _x (Fe _0.75 Co _0.25 ) _100-x alloy
The characteristic view which shows the relationship between m content rate and saturation magnetostriction constant (lambda) s.

FIG. 4 is a characteristic diagram showing the relationship between the composition of the FeCo film and the saturation magnetic flux density Bs of the artificial lattice film in the artificial lattice film in which the FeCo film and the ferrite film are laminated.

FIG. 5 is a schematic diagram showing a surface structure of a MgO (100) plane.

FIG. 6 is a schematic diagram showing a surface structure of a bccFe (100) plane.

FIG. 7 is a schematic diagram showing a state in which FIGS. 5 and 6 are overlapped.

FIG. 8 is a crystal plane index n / m and ΔEa / K of the FeCo film.
A characteristic diagram showing the relationship with ₁ .

FIG. 9: Various types of FeCo having different crystal planes parallel to the substrate surface
FIG. 6 is a characteristic diagram showing a relationship between an excitation frequency and a magnetic permeability when the film is subjected to high frequency excitation in the hard axis direction.

FIG. 10 is a cross-sectional view showing a magnetic artificial lattice film in Example 1 of the present invention.

FIG. 11 is a sectional view showing a magnetic artificial lattice film in Example 2 of the present invention.

FIG. 12 is a sectional view showing a magnetic artificial lattice film in Example 3 of the present invention.

13 is a characteristic diagram showing the relationship between the film thickness of the ferrite layer and the initial magnetic permeability μ _i and the saturation magnetic flux density Bs at 10 MHz in the magnetic artificial lattice film of Example 3. FIG.

FIG. 14 is a cross-sectional view of a planar inductor manufactured by using the magnetic artificial lattice film of the third embodiment.

15 is a DC-D to which the planar inductor of FIG. 14 is applied.
The circuit diagram of a C converter.

FIG. 16 is a sectional view showing a magnetic artificial lattice film in Example 4 of the present invention.

FIG. 17 is a diagram showing a magnetization curve of an as-deposited film of a FeCo single-layer film formed on a MgO (110) single crystal substrate in a reference example.

FIG. 18 is a diagram showing a magnetization curve of the FeCo single layer film formed on the MgO (110) single crystal substrate in the reference example after the heat treatment.

FIG. 19 is a diagram showing a magnetic torque curve of an as-deposited film of an FeCo single-layer film formed on a MgO (110) single crystal substrate in a reference example.

FIG. 20 is a diagram showing a magnetic torque curve of an FeCo single layer film formed on a MgO (110) single crystal substrate in a reference example after the heat treatment.

FIG. 21 is a diagram showing a magnetic torque curve of an as-deposited film of a FeCo single-layer film formed on a MgO (100) single crystal substrate in a reference example.

FIG. 22 is a characteristic diagram showing a relationship between an excitation frequency and a magnetic permeability when a FeCo single layer film formed on a MgO (110) single crystal substrate in a reference example is subjected to high frequency excitation in the hard axis direction.

FIG. 23 is a sectional view showing a magnetic artificial lattice film in Example 5 of the present invention.

FIG. 24 is a diagram showing a magnetization curve of a magnetic artificial lattice film of Example 5 of the present invention.

FIG. 25 is a characteristic diagram showing the relationship between the excitation frequency and the relative permeability when the magnetic artificial lattice film of Example 5 of the present invention was subjected to high frequency excitation in the hard axis direction.

FIG. 26 is a plan view showing a magnetic artificial lattice film processed into a strip shape in Example 6 of the present invention.

FIG. 27 is a plan view showing a magnetic artificial lattice film processed into a frame shape in Example 6 of the present invention.

FIG. 28 is a characteristic diagram showing the relationship between the excitation frequency and the relative permeability when the two types of magnetic artificial lattice films of Example 5 of the present invention were subjected to high-frequency excitation in the hard axis direction.

29 (a) and 29 (b) are the magnetic artificial lattice films of Comparative Example 1 with <-1, 1, 1 of the FeCo film of the first layer.
The figure which shows the magnetization curve measured by applying a magnetic field to each of a> direction and a <0,1, -1> direction.

[Explanation of symbols]

1 ... Substrate, 2 ... Ferromagnetic thin film, 3 ... Intermediate layer, 4 ... Artificial lattice film, 11 ... Glass substrate, 12 ... FeCo film, 13 ... Sm
FeCo film, 14, 15 ... Artificial lattice film, 21 ... Glass substrate, 22 ... Fe ₆₀ Co ₄₀ film, 23 ... Co _0.05 Ni _0.95 F
e ₂ O ₄ film, 24 ... Artificial lattice film, 25 ... Insulating film, 26 ...
Flat spiral coil, 31 ... Silicon substrate, 32 ... S
iO ₂ film, 33 ... Fe ₈₀ Co ₂₀ film, 34 ... Co _0.1 Ni
_0.9 Fe ₂ O ₄ , 35 ... Artificial lattice film, 41 ... MgO (1
10) Substrate, 41 '... MgO (100) substrate, 42 ... F
eCo film, 43 ... FeCoO film, 44, 44 '... Artificial lattice film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Tomita 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. (72) Inventor Hiromi Fukuya Komu-shishi-cho, Kawasaki-shi, Kanagawa No. 1 inside Toshiba Research Institute, Inc. (72) Inventor Atsuhito Sawana No. 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside Toshiba Research Institute, Inc.

Claims (3)

[Claims] 1. A FeCo-based ferromagnetic thin film and RFeCo
A magnetic artificial lattice film, characterized in that a magnetic alloy thin film (R is at least one element selected from the group consisting of Pm, Sm, Er and Tm) is laminated. 2. A magnetic artificial lattice film comprising a FeCo-based ferromagnetic thin film and a spinel ferrite magnetic thin film laminated together. 3. An Fe-based or FeCo-based ferromagnetic thin film and a NaCl-type ionic compound thin film containing at least one element selected from the group consisting of Fe, Co and Mg are laminated by heteroepitaxy. Characteristic magnetic artificial lattice film.