tetragonal thin film structures

Abstract

To provide a tetragonal thin film structure with better properties.SOLUTION: A tetragonal thin film structure has a support substrate 10 having at least a portion of a (110) oriented main surface and a crystal structure belonging to the cubic or tetragonal crystal, and a tetragonal thin film 20 formed on the (110) oriented main surface of the support substrate 10 and having an in-plane orientation of one axis in the plane in contact with the main surface.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a tetragonal thin film structure having a tetragonal thin film on a support substrate, and is suitable for application to, for example, a thin film of FeNiN or an L10 type FeNi ordered alloy having an L10 type ordered structure as the tetragonal thin film. [Background technology]

[0002] FeNi (iron-nickel) ordered alloys with an L10 ordered structure have high magnetic anisotropy and are expected to be used as rare earth or precious metal-free magnet materials and magnetic device materials for magnetic recording, etc. L10 ordered FeNi alloy thin films can be formed by denitrifying an FeNiN thin film prepared by molecular beam epitaxy (MBE) in nitrogen plasma on an STO (strontium titanate: SrTiO3) support substrate (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] K. Ito et al., "Epitaxial L10-FeNi films with high degree of order and large uniaxial magnetic anisotropy fabricated by denitriding FeNiN films", Applied Physics Letters. 116, 242404(2020) Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an FeNiN thin film is formed on a support substrate whose main surface has a (100) plane orientation using the manufacturing method disclosed in Non-Patent Document 1, it was confirmed that two types of variants are formed, in which the c-axes of the FeNiN intersect at 90°. This is because the crystal structure on the (100) plane has four-fold symmetry around the central axis, and the FeNiN grows so that the c-axis intersects each side of the cubic crystal structure, resulting in a multi-variant state. The size of each variant in this case was approximately 5 nm.

[0005] In a multi-variant state where the crystal orientation axes are orthogonal, the magnetic, electrical, and optical properties of the orientation directions that are superior are averaged with the properties of the orientation directions that are inferior, which poses a problem in that the properties that would be obtained in a single-variant state cannot be utilized. For example, the magnetocrystalline anisotropy constant Ku becomes an average value between orthogonal variants, resulting in a decrease in magnetocrystalline anisotropy.

[0006] The term "variant" here refers to the crystal orientation of a tetragonal thin film when it is deposited on a support substrate. "Single variant" means that the crystal orientation is in only one axis, while "multi-variant" means that the crystal orientation is in multiple axes. The entire tetragonal thin film does not need to be "single variant," but if the dimensions of each variant are small, there will be no dominant variant, and the properties will average out, resulting in poor performance. Therefore, in order to obtain better properties, it is important to be able to obtain large dimensions for the single variant.

[0007] In view of the above, an object of the present invention is to provide a tetragonal thin film structure having a structure with superior characteristics. [Means for solving the problem]

[0008] In order to achieve the above object, a tetragonal thin film structure according to claim 1 comprises a support substrate (10) having a crystal structure belonging to a cubic or tetragonal system, at least a part of which has a main surface of a (110) plane orientation, and a tetragonal thin film (20) formed on the main surface of the support substrate of a (110) plane orientation and having a uniaxial in-plane orientation in a plane in contact with the main surface. The support substrate has a cubic crystal structure, and the RMS mismatch difference between the (110) plane orientation of the main surface of the support substrate and the (110) and (101) plane orientations of the tetragonal thin film is 1.9% or less. . A tetragonal thin film structure according to claim 8 comprises a support substrate (10) having a crystal structure belonging to a cubic or tetragonal system, at least a part of which has a main surface of (110) plane orientation, and a tetragonal thin film (20) formed on the main surface of the support substrate of (110) plane orientation and having uniaxial in-plane orientation in a plane in contact with the main surface, wherein the support substrate is made of LaAlO 3 The tetragonal thin film is a thin film of FeNiN or an L10 type FeNi ordered alloy having an L10 type ordered structure, and has an island structure, with at least one outer surface of each island being a {111} plane.

[0009] In this way, by using a support substrate with a cubic or tetragonal crystal structure having at least a portion of a main surface with a (110) plane orientation and forming a tetragonal thin film on the support substrate, the crystal of the tetragonal thin film can be made to be a single variant, thereby making it possible to obtain a tetragonal thin film structure with a structure having superior properties.

[0010] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0011] [Figure 1A] 1 is a cross-sectional view of a tetragonal thin film structure according to one embodiment of the present invention. [Figure 1B] 1B is a top view of a tetragonal thin film in the tetragonal thin film structure shown in FIG. 1A. FIG. [Figure 2A] FIG. 1 is a cross-sectional view of a tetragonal thin film structure according to a comparative example. [Figure 2B] 2B is a top view of a tetragonal thin film in the tetragonal thin film structure shown in FIG. 2A. FIG. [Figure 3] (a) is a perspective view of the crystal structure of STO, and (b) and (c) are diagrams showing the crystal structures of STO(100) and STO(110), respectively, when viewed from the normal direction of each plane. [Figure 4](a) is a perspective view of the crystal structure of FeNiN, (b) is a perspective view in which the (110) plane is hatched, and (c) and (d) are diagrams showing the crystal structures of FeNiN(100) and FeNiN(110), respectively, when viewed from the normal direction of each plane. [Figure 5] This is a diagram showing the alignment between STO(100) and FeNiN(100). [Figure 6] This is a diagram showing the lattice mismatch and RMS (root mean square) mismatch between each material and FeNiN(110) when the support substrate is made of MgO(110), STO(110), or LAO(110). [Figure 7] (a) is a perspective view of the crystal structure of FeNiN, with the (110) and (101) planes hatched, (b) is a diagram showing the (110) orientation of FeNiN, and (c) is a diagram showing the (101) orientation of FeNiN. [Figure 8] 1 is a diagram showing the lattice mismatch and RMS mismatch between each material and FeNiN(101) when the support substrate is made of MgO(110), STO(110), or LAO(110). [Figure 9] FIG. 1 is a diagram showing the relationship between the cubic lattice constant and the RMS mismatch when the support substrate is made of MgO(110), STO(110), or LAO(110). [Figure 10] FIG. 1 is a diagram showing the relationship between the cubic lattice constant and the difference in RMS mismatch between the (110) and (101) plane orientations. [Figure 11] 1 is a table summarizing the results of in-plane orientation, in-plane (001) orientation rate, and in-plane (110) orientation rate in Comparative Example 1 and Examples 1 to 5. [Figure 12] FIG. 2 shows X-ray diffraction patterns obtained when X-rays are incident so that the scattering vector of the X-rays is in the normal direction to the surface of the tetragonal thin film in Comparative Example 1 and Examples 1 to 3. [Figure 13] FIG. 2 shows X-ray diffraction patterns obtained when X-rays are incident on the surfaces of tetragonal thin films in Comparative Example 1 and Examples 1 to 3 so that the scattering vector of the X-rays is in one direction within the surface. [Figure 14] 13. FIG. 14 shows X-ray diffraction patterns when X-rays are incident on the surfaces of tetragonal thin films in Comparative Example 1 and Examples 1 to 3 so that the scattering vector of the X-rays is perpendicular to that of FIG. [Figure 15] 1 is a diagram summarizing the main peaks of FeNiN. [Figure 16] FIG. 1 shows the results of investigating the in-plane magnetic properties of a tetragonal thin film made of an L10 type FeNi ordered alloy thin film. [Figure 17] FIG. 1 is a cross-sectional view of a tetragonal thin film structure according to Examples 4 and 5. [Figure 18] FIG. 10 shows the results of cross-sectional observation of the LAO(100) substrate in Example 4 from the [1-10] axis direction using a transmission electron microscope (TEM). [Figure 19] FIG. 19 is a diagram showing the results of a reciprocal lattice pattern analysis of the XIX region in FIG. 18 by fast Fourier transform (FFT). [Figure 20] FIG. 10 is a diagram showing the results of investigating the in-plane magnetic properties at 300 K of a tetragonal thin film that is an L10 type FeNi ordered alloy thin film according to Example 4. [Figure 21] FIG. 10 is a diagram showing the results of investigating the in-plane magnetic properties at 10 K of a tetragonal thin film that is an L10 type FeNi ordered alloy thin film according to Example 4. [Figure 22] 10 is a table showing magnetic properties in Examples 4 and 5. [Figure 23] FIG. 10 is a diagram showing the results of investigating the in-plane magnetic properties at 300 K of a tetragonal thin film that is an L10 type FeNi ordered alloy thin film according to Example 5. [Figure 24] This is a diagram showing the crystal structure of MgO using a face-centered cubic lattice as the basic unit cell. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0013] (First embodiment) A tetragonal thin film structure according to a first embodiment will be described with reference to Figures 1A and 1B. In Figures 1A and 1B, the arrows shown in the figures indicate the direction of the c-axis.

[0014] As shown in FIG. 1A, the tetragonal thin film structure of this embodiment is configured by forming a tetragonal thin film 20 on a support substrate 10.

[0015] The support substrate 10 has a cubic or tetragonal crystal structure, and at least a portion of the interface in contact with the tetragonal thin film 20 has a (110) plane orientation. For example, STO(110), LAO(110), or MgO(110) can be used as the support substrate 10. The cubic lattice constant of STO is 0.3905 nm. The cubic lattice constant of LAO is 0.379 nm. The cubic lattice constant of MgO is 0.4213 nm.

[0016] Note that LAO is lanthanum aluminate (LaAlO3), and MgO is magnesium oxide. The (110) written after STO, LAO, and MgO means that when the support substrate 10 is formed from these, the plane orientation of the main surface of the support substrate 10 is (110). While (110) is mentioned here, the same applies to (100), (001), etc., which will be described later.

[0017] As shown in FIGS. 1A and 1B, the tetragonal thin film 20 is a thin film with uniaxial in-plane orientation on one surface in contact with the main surface of the support substrate 10. The tetragonal thin film 20 has a uniaxial in-plane orientation, with the arrow indicating the

[0001] direction, a (001) orientation in the direction of the arrow, and a (110) orientation with respect to the interface with the support substrate 10. More specifically, the tetragonal thin film 20 does not have a (001) orientation in the vertical direction, and has an in-plane (001) orientation rate, which is the proportion of components containing variants oriented in the same direction, of 60% or more, preferably 70% or more. Furthermore, the in-plane (110) orientation rate rotated 90° in-plane is 60% or more, preferably 70% or more. Examples of the tetragonal thin film 20 include thin films of materials containing elements Fe, Ni, and N, and thin films of L10-type FeNi ordered alloys having an L10-type ordered structure.

[0018] An example of a thin film made of a material containing Fe, Ni, and N is FeNiN. In the case of FeNiN, the lattice constant along the a-axis of FeNiN(100) is 0.4002 nm, and the lattice constant along the c-axis of FeNiN(001) is 0.3713 nm. When the tetragonal thin film 20 is made of FeNiN, it can be obtained by a method of depositing FeNi on the support substrate 10 in nitrogen plasma, or by a method of depositing Fe and Ni layers alternately and then performing a nitriding treatment. Furthermore, when the tetragonal thin film 20 is made of FeNiN, it may contain components other than FeNiN, such as FeNiN, FeNi, or oxides.

[0019] Furthermore, when the tetragonal thin film 20 is an L10 type FeNi ordered alloy thin film having an L10 type ordered structure, a thin film of the L10 type FeNi ordered alloy can be obtained by forming an FeNiN thin film and then performing a denitrification process. If the tetragonal thin film 20 is an L10 type FeNi ordered alloy thin film, the tetragonal thin film structure becomes an FeNi ordered alloy structure including an FeNi superlattice. Such an FeNi ordered alloy structure is applicable to magnetic materials and device materials for magnetic recording, magnetic sensors, etc., and has excellent magnetic properties with high coercivity.

[0020] Here, the tetragonal thin film structure of this embodiment will be compared with a conventional case where a tetragonal thin film is formed on the main surface of STO (100). Here, an example will be given where the support substrate is STO and the tetragonal thin film is FeNiN. In the following explanation, the structure where a tetragonal thin film is formed on the main surface of STO (100) will be referred to as the comparative structure.

[0021] In a comparative structure in which a tetragonal thin film J20 is formed on an STO(100) support substrate J10 as shown in Figure 2A, two types of variants are formed in which the c-axes of FeNiN intersect at 90°, as shown in Figure 2B. TEM (transmission electron microscope) observations revealed that the dimensions of each variant were small, approximately 5 nm.

[0022] As shown in (a) of Figure 3, STO has a cubic crystal structure. Therefore, the STO (100) used for the support substrate J10 in the comparative structure has four-fold symmetry, meaning that the same lattice structure is obtained every time it is rotated 90° around the central axis, as shown in (b) of Figure 3. In contrast, the STO (110) used for the support substrate 10 in the structure of this embodiment has two-fold symmetry, meaning that the same lattice structure is obtained every time it is rotated 180° around the central axis, as shown in (c) of Figure 3.

[0023] On the other hand, as shown in Figure 4(a), FeNiN has a tetragonal crystal structure, with a layer where Ni is arranged and a layer where Fe and N are arranged. As shown in Figure 4(c), FeNiN(100) has a crystal structure close to STO(100). Note that the crystal structure of FeNiN(110) viewed from the normal direction of the (110) plane shown in Figure 4(b) has a surface arrangement different from that of STO(100), as shown in Figure 4(d).

[0024] As shown in Figure 5, in a comparative structure using STO(100) as the support substrate J10, the axes of the STO(100) and the a-axis of the FeNiN(100) are aligned, allowing the epitaxial growth of FeNiN(100) on the support substrate J10. Because STO(100) is a cubic crystal, the atomic arrangement and lattice constants of the mutually orthogonal axes are identical. Therefore, when growing FeNiN using a cubic support substrate J10 with a (100) plane orientation, there are two possible axial directions that can be aligned with the FeNiN, i.e., two possible growth directions. Therefore, as shown in Figures 2A and 2B, two variants of the FeNiN constituting the tetragonal thin film J20 are formed, in which the c-axes of the FeNiN intersect at 90°.

[0025] In contrast, in the structure of this embodiment, in which STO (110) is used as the support substrate 10, only the c-axis of STO (110) is compatible with FeNiN. Therefore, when growing FeNiN using a support substrate 10 with a cubic crystal and a (110) plane orientation, there is only one axial direction that is compatible with FeNiN, that is, the growth direction is limited to only one direction. For this reason, as shown in FIGS. 1A and 1B, the c-axis of the FeNiN that constitutes the tetragonal thin film 20 becomes a single variant, oriented in a single direction.

[0026] In this way, by using a support substrate 10 with a cubic or tetragonal crystal structure with a (110) plane orientation and depositing a tetragonal thin film 20 on the support substrate 10, the crystals of the tetragonal thin film 20 can be made to be single variant. This makes it possible to obtain a tetragonal thin film structure with superior properties. Note that the tetragonal thin film 20 does not need to be single variant throughout its entirety; it is sufficient to obtain a single variant with large dimensions, for example, 30 nm or more. In other words, it is acceptable for there to be portions of other variants, as long as the dimensions of the single variant portions are sufficiently larger than the dimensions of the other portions.

[0027] Although the case where the support substrate 10 is STO(110) has been taken as an example here, the effect of reducing variants for each material will be explained by comparing with the cases where MgO(110) and LAO(110) are used.

[0028] Figure 6 shows the lattice mismatch and RMS mismatch between the support substrate 10 and FeNiN(110) when the support substrate 10 is made of cubic oxides MgO(110), STO(110), and LAO(110). FeNiN(110)

[0001] in the figure indicates that the mismatch was measured along the

[0001] axis of FeNiN(110). Similarly, FeNiN(110)[1-10] in the figure indicates that the mismatch was measured along the 【1-10】 axis of FeNiN(110). The RMS mismatch is the root mean square of the mismatch in FeNiN(110)

[0001] and the mismatch in FeNiN(110)[1-10]. The RMS mismatch degree is an index showing the overall degree of lattice mismatch in the

[0001] axial direction and the [1-10] axial direction.

[0029] As shown in this figure, in FeNiN(110)

[0001] , the absolute mismatch values ​​are LAO(110), STO(110), and MgO(110) in descending order. In FeNiN(110) [1-10], the absolute mismatch values ​​are large for MgO(110) and LAO(110), while the absolute mismatch value is small for STO(110). The RMS mismatch values ​​are smallest for STO(110), followed by LAO(110), and largest for MgO(110).

[0030] A large single variant can be obtained using any of the MgO(110), STO(110), and LAO(110) substrates 10. Basically, it is believed that the smaller the absolute value of the mismatch in the

[0001] and [1-10] axial directions in FeNiN(110), the greater the effect of reducing variants.

[0031] However, in an experiment in which FeNiN was grown as a tetragonal thin film 20 using MgO(110), STO(110), and LAO(110) as the support substrate 10, it was found that LAO(110) had a greater effect of reducing variants than STO(110). This is thought to be because when the tetragonal thin film 20 is grown using the (110) plane orientation, the (101) plane can also grow.

[0032] As shown in Figure 7(a), in FeNiN, the (110) plane is indicated by solid hatching, and the (101) plane is indicated by dashed hatching. Figure 7(b) shows FeNiN with a (110) orientation, as viewed from the STO

[0110] and FeNiN

[0110] directions. This figure shows the crystal structure of FeNiN grown on a (110)-oriented support substrate 10 with a (110) orientation. When FeNiN grows with a (110) orientation, as shown in this figure, the c-axis is uniquely determined. On the other hand, (c) in Figure 7 shows FeNiN with a (101) orientation, as seen from the STO <0110> direction and the FeNiN <0010> direction, and shows the crystal structure when a support substrate 10 with a (110) orientation is placed below the FeNiN crystal structure, and FeNiN grows on top of it with a (101) orientation. As shown in this figure, when FeNiN grows with a (101) orientation, growth in two directions along the c-axis is possible, resulting in multivariant structures.

[0033] Therefore, it is desirable not to grow in the FeNiN(101) direction. To prevent FeNiN from growing on the (101) plane, the RMS mismatch with FeNiN(101) must be large enough.

[0034] Figure 8 shows the lattice mismatch and RMS mismatch between the support substrate 10 and FeNiN(101) when the support substrate 10 is made of cubic oxides MgO(110), STO(110), and LAO(110). FeNiN(101)

[0010] in the figure indicates that the mismatch was measured along the

[0010] axis of FeNiN(101). Similarly, FeNiN(101)[-101] in the figure indicates that the mismatch was measured along the [-101] axis of FeNiN(101). The RMS mismatch is the root-mean-square of the mismatch in FeNiN(101)

[0010] and FeNiN(101)[-101]. The RMS mismatch is an index of the overall lattice mismatch along the

[0010] and [-101] axes.

[0035] As shown in this figure, in FeNiN(101)

[0010] , the order of the absolute mismatch is STO(110), MgO(110), and LAO(110). In FeNiN(101)[-101], the order of the absolute mismatch is STO(110), LAO(110), and MgO(110). In terms of RMS mismatch, STO(110) has the smallest RMS mismatch, followed by LAO(110), and then MgO(110).

[0036] To grow FeNiN(110), a low RMS mismatch is preferable, and in that sense, STO(110) is preferable, as shown in Figure 6. However, to prevent the growth of FeNiN(101), a high RMS mismatch is preferable, and LAO(110) or MgO(110) are better than STO(110). Therefore, the experimental results show that using LAO(110) is more effective at reducing variants than using STO(110).

[0037] The relationship between the cubic lattice constant and the RMS mismatch was investigated for FeNiN(110) and FeNiN(101) when MgO(110), STO(110), and LAO(110) were used as the support substrate 10. The results shown in Figure 9 were obtained. The relationship between the cubic lattice constant and the RMS mismatch difference, i.e., the difference in the RMS mismatch between FeNiN(110) and FeNiN(101), was also investigated. The results shown in Figure 10 were obtained. The RMS mismatch difference is the RMS mismatch of the desired orientation minus the RMS mismatch of the undesired orientation. In this case, it is the FeNiN(110) RMS mismatch minus the FeNiN(101) RMS mismatch.

[0038] As shown in Figure 9, there appears to be a correlation between the cubic lattice constant and the RMS mismatch. For both FeNiN(110) and FeNiN(101), the RMS mismatch is smallest near 0.3905 nm, the cubic lattice constant of STO(110). The RMS mismatch increases as the cubic lattice constant decreases or increases. However, as the cubic lattice constant decreases below that of STO(110), the RMS mismatch difference decreases. In other words, the RMS mismatch difference for STO(110) is 1.97%, while for LAO(110), the RMS mismatch difference is nearly 0%.

[0039] If the RMS mismatch of FeNiN(110) and FeNiN(101) were originally the same, FeNiN(110) would be more likely to form than FeNiN(101) from the viewpoint of the stability of the surface energy, etc. Therefore, even if FeNiN(110) becomes somewhat larger, it is thought that FeNiN(110) was preferentially formed because the RMS mismatch difference, which is the difference between the RMS mismatch between the (110) and (101) surface orientations, is small.

[0040] Therefore, if a cubic crystal structure with a smaller RMS mismatch difference is used, the orientation can be controlled, for example, FeNiN(110) is preferentially formed, and a single variant can be obtained, thereby enhancing the variant reduction effect. Specifically, if a cubic crystal structure with a lattice constant of 1.9% or less, which is smaller than the 1.97% in the case of STO(110), or 0.39 nm or less, which is smaller than 0.3905 nm in cubic crystal lattice constant, is used, a greater variant reduction effect than STO(110) can be achieved.

[0041] Although STO(110), LAO(110), and MgO(110) are used as examples of materials for the support substrate 10 having a cubic crystal structure, the present invention is not limited to these. Figures 9 and 10 show the RMS mismatch and RMS mismatch difference calculated from the cubic lattice constant, plotted as approximate curves. The calculation results for STO(110), LAO(110), and MgO(110) are also plotted. This approximate curve shows the RMS mismatch and RMS mismatch difference corresponding to the cubic lattice constant of a material. For materials other than STO(110), LAO(110), and MgO(110), the relationship between the cubic lattice constant and the RMS mismatch and RMS mismatch difference generally corresponds to this approximate curve. Therefore, even if a material other than STO(110), LAO(110), or MgO(110) is used, if it has a cubic crystal structure of 1.9% or less, which is smaller than the 1.97% in the case of STO(110), a greater variant reduction effect than STO(110) can be achieved. [Example]

[0042] Next, a comparative structure using STO (100) was used as Comparative Example 1, and FeNiN was grown using STO (110), MgO (110), and LAO (110) as Examples 1 to 3, respectively. Specifically, the temperature of the support substrate 10 was set to 350°C, and a 20-nm FeNiN film was epitaxially grown on the support substrate 10 as a tetragonal thin film 20 by MBE with simultaneous supply of Fe, Ni, and radio-frequency (RF) N2. The N2 flow rate into the chamber of the growth apparatus was 1.0 sccm, and the RF input was 280 W. Comparative Example 1 and Examples 1 to 3 will be described with reference to FIG. 11. The results shown in FIG. 11 were obtained based on the X-ray diffraction results shown in FIGS. 12 to 14, which will be described later.

[0043] (Comparative Example 1) First, a comparative structure was fabricated and the FeNiN perpendicular orientation direction and in-plane (001) orientation rate were investigated. As a result, as shown in Figure 11, it was found that the (100) orientation was perpendicular to the substrate, and (001) was not perpendicular to the surface. The in-plane (001) orientation rate was 57.5%. In other words, it was confirmed that a multi-variant state existed, with two variants perpendicular to the surface in the

[0001] direction.

[0044] Example 1 In Example 1, FeNiN was deposited as a tetragonal thin film 20 using a support substrate 10 made of STO (110), and the FeNiN perpendicular orientation direction and in-plane (001) orientation rate were investigated. As a result, as shown in Figure 11, it was found that the orientation direction perpendicular to the substrate was (110), and (001) was not perpendicular to the surface. The in-plane (001) orientation rate was 72.7%, indicating a higher in-plane (001) orientation than in Comparative Example 1. Furthermore, the (110) in-plane orientation rate was 69.7%, indicating a (110) orientation.

[0045] Example 2 In Example 2, FeNiN was deposited as a tetragonal thin film 20 using a support substrate 10 composed of MgO (110), and the FeNiN perpendicular orientation direction and in-plane (001) orientation rate were investigated. As a result, as shown in Figure 11, it was found that the substrate orientation direction perpendicular to the plane was (110), and (001) was not perpendicular to the plane. The in-plane (001) orientation rate was 72.7%, indicating a higher (001) orientation than in Comparative Example 1. Furthermore, the in-plane (110) orientation rate was 69.7%, indicating a (110) orientation.

[0046] Example 3 In Example 3, FeNiN was deposited as a tetragonal thin film 20 using a support substrate 10 composed of LAO (110), and the FeNiN perpendicular orientation direction and in-plane (001) orientation rate were investigated. As a result, as shown in FIG. 11 , it was found that the substrate orientation direction perpendicular to the plane was (110), and (001) was not perpendicular to the plane. The in-plane (001) orientation rate was 98.1%, indicating a higher (001) orientation than in Comparative Example 1. Furthermore, the in-plane (110) orientation rate was 95.9%, indicating a higher (110) orientation than in Examples 1 and 2. In other words, both the in-plane (001) orientation rate and the in-plane (110) orientation rate were high, confirming that a single variant with the largest dimensions was obtained among Examples 1 to 3.

[0047] For Comparative Example 1 and Examples 1 to 3, X-rays were irradiated from multiple directions to examine the X-ray diffraction patterns. Specifically, X-rays were irradiated in two directions within the plane of the tetragonal thin film 20 in contact with the main surface, where the scattering vector of the X-ray diffraction is normal to the surface of the tetragonal thin film 20, i.e., normal to the main surface of the support substrate 10 (hereinafter referred to as the first direction), and the X-ray diffraction patterns were examined. The two in-plane directions are two directions that are orthogonal within the plane, and hereinafter, one of these directions will be referred to as the second direction, and the other direction perpendicular to the second direction will be referred to as the third direction.

[0048] 12 to 14 show X-ray diffraction patterns obtained when X-rays are incident in the first to third directions, respectively, for Comparative Example 1 and Examples 1 to 3. In FIG. 12, X-rays are incident so that the scattering vector of X-ray diffraction is aligned with the first direction, which is the normal direction to the surface of the tetragonal thin film 20, resulting in an X-ray diffraction pattern that reflects the crystalline structure of the tetragonal thin film 20 in the normal direction. In addition, in FIGS. 13 and 14, X-rays are incident so that the scattering vector of X-ray diffraction is aligned with the second and third directions, which are in-plane on the surface of the tetragonal thin film 20, resulting in X-ray diffraction patterns that reflect the crystalline structure of the tetragonal thin film 20 in the in-plane direction. In Comparative Example 1, the second direction is the

[0001] direction of the substrate, and in the third direction, the diffraction intensity is simply swapped between 002 and 200 due to substrate symmetry; therefore, the X-ray diffraction pattern for Comparative Example 1 is not shown in FIG. 14. In Examples 1 to 3, if the second direction is the

[0001] direction of the substrate, then the third direction corresponds to the

[0110] direction of the substrate. X-ray diffraction measurements were performed by depositing an FeNiN film on a 10 mm square, 0.5 mm thick support substrate 10, and then irradiating it with CuKa radiation at a wavelength λ of 0.15418 nm in each of the first to third directions. The angle 2θ (degrees) was measured in 0.02° increments in the range of 38 to 72°.

[0049] First, the main X-ray diffraction peaks of FeNiN are shown in Figure 15. For example, (200) indicates that the peak occurs at an angle 2θ (degrees) of 45.317°. Regarding the angle 2θ (degrees) that could be the peak shown in this figure, we determined whether a peak appeared within a 1.0° angle range nearby. The diffraction intensity background and error were calculated, for example, in the range of 53–57°, where no peaks exist for FeNiN or the substrate. The peak intensity was calculated by averaging within a 0.1° range around the peak top. If the peak intensity is higher than the diffraction intensity background, it can be said that there is an orientation direction at that angle 2θ (degrees). Furthermore, because the diffraction intensity of the (001) and (110) peaks is weak, they were not used to determine the crystal structure.

[0050] 13 shows the in-plane (001) orientation ratio within the surface of the tetragonal thin film 20. The in-plane (001) orientation ratio was calculated to determine the degree of in-plane orientation. The in-plane (001) orientation ratio was calculated by determining the peak intensities of peaks exhibiting fundamental reflections such as FeNiN(200) and FeNiN(002), and then adding up these peak intensities to calculate the proportion of the (001) orientation. In other words, the in-plane (001) orientation ratio was calculated based on peaks exhibiting fundamental reflections such as FeNiN(200) and FeNiN(220), which are not due to diffraction intensity background or error and are not derived from the support substrate 10. 14 also shows the in-plane (110) orientation ratio within the surface of the tetragonal thin film 20. The in-plane (110) orientation ratio was calculated to examine the degree of in-plane orientation in the third direction, and Comparative Example 1 was excluded due to the symmetry of the substrate. The in-plane (110) orientation ratio was calculated by determining the peak intensities of peaks exhibiting fundamental reflections such as FeNiN(220) and FeNiN(202), and then calculating the proportion of these peak intensities that were accounted for by the (220) orientation direction. In other words, the in-plane (110) orientation ratio was calculated based on peaks exhibiting fundamental reflections such as FeNiN(200) and FeNiN(220), which are not due to diffraction intensity background or error and are not derived from the support substrate 10.

[0051] In the case of FeNiN, if the support substrate 10 is STO(100), a peak should preferably appear at (n00), an integer multiple n of that, such as (200), and if the support substrate 10 is STO(110), a peak should preferably appear at (nn0), an integer multiple n of that, such as (220). Furthermore, the appearance of a peak at (202), which is not an integer multiple, indicates a multivariant state.

[0052] 12, a peak appears in FeNiN(200) but no peak appears in FeNiN(002) in Comparative Example 1. This indicates that the a-axis is parallel to the direction perpendicular to the (100) plane, and that there is almost no c-axis perpendicular to the STO(100) plane.

[0053] In addition, in Examples 1 to 3, a peak appears at FeNiN(220), and no peak appears at angles 2θ (degrees) corresponding to other directions such as FeNiN(002). In particular, in Example 3, a large peak intensity appears at (220).

[0054] On the other hand, in Figure 13, two peaks appear for FeNiN(200) and FeNiN(002). This means that c-axes in different directions exist within the STO(100) plane, meaning that two types of variants have been formed in which the c-axes of FeNiN intersect at 90°, as shown in Figures 2A and 2B. Furthermore, the intensities of the two peaks for FeNiN(200) and FeNiN(002) are almost equal, which indicates that the c-axes in the two directions appear almost equally and that each variant occurs almost equally.

[0055] In Examples 1 to 3, two peaks, FeNiN(200) and FeNiN(002), appear, but there is a difference between the two peaks. This means that the orientation is in the direction corresponding to the peak with the greater intensity, and it can be seen that a single variant with a large dimension is obtained. A similar result can be seen in FIG. 14. As shown in FIGS. 13 and 14, the orientation rate in Comparative Example 1 was less than 60%, while in Examples 1 to 3 it was 60% or higher, and most were 70% or higher. In particular, when the support substrate 10 was made of LAO, a high in-plane (001) orientation rate of 95% or higher was obtained, indicating that a single variant with a large dimension was obtained.

[0056] Furthermore, a film of FeNiN was formed on the main surface of the support substrate 10, which was made of LAO (110), and then denitrification treatment was performed to form the tetragonal thin film 20 into an L10 type FeNi ordered alloy thin film, and the in-plane magnetic properties of the tetragonal thin film 20 were then investigated. Figure 16 shows the results, showing the magnetic properties in the direction parallel to the c-axis and the magnetic properties in the direction perpendicular to the c-axis. A sample was prepared in which an L10 type FeNi ordered alloy thin film was formed as the tetragonal thin film 20 on the support substrate 10, and an external magnetic field was applied and swept to examine the M / M s The change in was measured.

[0057] As shown in Figure 16, the magnetic properties are completely different in the directions parallel and perpendicular to the c-axis. The crystal structure of the L10 type FeNi ordered alloy is composed of a stacked structure of Fe and Ni layers, and has the property of being easily magnetized in the stacking direction. Therefore, even if a small magnetic field is applied in the direction parallel to the c-axis, i.e., in the stacking direction of the Fe and Ni layers, M / M s becomes large, making it easy to magnetize, and unless a large magnetic field is applied in the direction perpendicular to the c axis, M / M s This indicates that the L10 type FeNi ordered alloy thin film has a highly in-plane oriented crystal. s indicates the saturation magnetization.

[0058] Next, Examples 4 and 5 will be described. Examples 4 and 5 were obtained by using LAO(110) as the support substrate 10, depositing an FeNi film on the LAO(110), nitriding it in an ammonia gas atmosphere to form an FeNiN film, and then denitriding it in a hydrogen gas atmosphere. Specifically, the temperature of the support substrate 10 was set to 400°C, and an FeNi film was deposited on the support substrate 10 by radio frequency (RF) sputtering using a 50:50 atm% FeNi alloy target to a thickness of 16.6 nm in Example 4 and 12.7 nm in Example 5. The FeNi thin film samples were then nitrided in an ammonia gas atmosphere at 325°C for 20 hours, and then further nitrided at 375°C for 10 hours to form FeNiN. The FeNiN perpendicular orientation, in-plane (001) orientation ratio, and in-plane (110) orientation ratio were measured for Examples 4 and 5, and the results shown in FIG. 11 were obtained. Thereafter, denitrification treatment was carried out in a hydrogen gas atmosphere at 200° C. for 2 hours, thereby obtaining samples of Examples 4 and 5 in which a tetragonal thin film 20 of an L10 type FeNi ordered alloy was formed on a support substrate 10.

[0059] Example 4 In Example 4, FeNiN was deposited as a tetragonal thin film 20 using a support substrate 10 composed of LAO (110) and nitrided. The FeNiN perpendicular orientation direction and in-plane (001) orientation ratio were investigated. As shown in FIG. 11 , the orientation perpendicular to the substrate was (110). The in-plane (001) orientation ratio was 93.2%, indicating a higher (001) orientation ratio compared to Comparative Example 1. Furthermore, the in-plane (110) orientation ratio was 100%, indicating a higher (110) orientation compared to Examples 1 to 3. In other words, both the in-plane (001) orientation ratio and the in-plane (110) orientation ratio were high, confirming that a higher orientation, i.e., a wider single-variant region, was obtained than in Examples 1 and 2. Furthermore, because the denitrification reaction from FeNiN is a topotactic reaction that maintains the ordered structure of Fe and Ni, it is believed that the L10-type FeNi orientation ratio after denitrification from FeNiN is similar to that of FeNiN.

[0060] Furthermore, in Example 4, it was found that a tetragonal thin film 20 having a plurality of island-like structures 21 scattered on a support substrate 10 was formed, as shown in FIG. 17 . Specifically, the denitrified sample was thinned by focused ion beam (FIB) processing to expose the cross section, and high-resolution cross-sectional TEM observation of the sample was performed from the [1-10] axis direction of LAO(110). As a result, it was found that the tetragonal thin film 20 has planes reflecting that the island-like structures 21 are FeNi single crystals with (110), (111), and (11-1) planes, and has at least one {111} plane, as shown in FIG. 18 . Note that in FIG. 18 , arrows and Miller indices are attached to the top and side surfaces of each particle constituting the tetragonal thin film 20 to make the crystal planes easier to understand. The notation {111} represents six types of equivalent planes: (111), (11-1), (1-11), (1-1-1), (-1-11), and (-1-1-1). The island-like structures 21 having at least one {111} plane means that the outer surface thereof has one or more planes corresponding to any one of the six types of equivalent planes: (111), (11-1), (1-11), (1-1-1), (-1-11), and (-1-1-1). In this specification, the symbol "-" in the Miller index notation refers to a bar that appears on the index immediately following it, as shown in FIG. 18, for example.

[0061] The tetragonal thin film 20 according to Example 4 had a large number of FeNi island structures 21, each about 30 nm thick, formed on an LAO(110) support substrate 10, and these island structures 21 were scattered to form an archipelago. The term "scattered" as used herein includes cases where the island structures 21 were spaced apart from one another, as well as cases where some of the island structures 21 were in contact with one another and other island structures 21 were spaced apart. When viewed from the [1-10] axis direction of LAO(110), the top surface of each of the multiple islands constituting the tetragonal thin film 20, i.e., the FeNi island structures 21, opposite the support substrate 10, was a (110) plane. Furthermore, the side surface adjacent to the top surface of each FeNi island structure 21 constituting the tetragonal thin film 20 was a {111} plane, and at least one of the outer surfaces was a {111} plane.

[0062] FIG. 19 shows the results of reciprocal lattice pattern analysis by FFT on the XIX region, which is 20 nm in the thickness direction relative to the support substrate 10 and 50 nm in the planar direction relative to the support substrate 10, as indicated by the dashed line in FIG. 18. In FIG. 19, Miller indices are added to some of the reflection diffraction spot patterns indicated by white dots. In FIG. 19, the white dots consist of diffraction spot patterns of basic reflections and diffraction spot patterns of superlattice reflections. Particularly bright white dots indicate diffraction spots of basic reflections, and the white dots indicated by the tips of the white arrows in the figure indicate diffraction spots of superlattice reflections. In Example 4, as shown in FIG. 19, the diffraction spots of 001 and 110 superlattice reflections were clearly observed, while the diffraction spots of other superlattice reflections were not clearly observed. This result indicates that the orientation direction of the L10-FeNi island structures 21 was uniform within an observation range of at least 20 nm × 50 nm, and a wide single-variant region of at least 20 nm × 50 nm or more was obtained.

[0063] Next, the results of evaluating the magnetic properties of Example 4 at 300K (Kelvin) and 10K are shown in FIGS.

[0064] The magnetic properties were measured using a vibrating sample magnetometer (VSM) at 300 K and a superconducting quantum interference device (SQUID) at 10 K. VSM stands for vibrating sample magnetometer, and SQUID stands for superconducting quantum interference device.

[0065] In Example 4, as shown in FIG. 20, when an external magnetic field was applied in the direction parallel to the c-axis plane at 300 K, the M / M phase was observed by applying a smaller external magnetic field than when an external magnetic field was applied in the direction perpendicular to the c-axis plane or perpendicular to the substrate surface. swas saturated. This indicates that the easy axis of magnetization in Example 4 is in the in-plane c-axis direction. Here, the c-axis in-plane parallel direction refers to the c-axis direction in the L10-type FeNi thin film plane, i.e., the direction parallel to the LAO

[0001] direction, and the c-axis in-plane perpendicular direction refers to the direction perpendicular to the c-axis direction, i.e., the LAO [1-10] direction. Furthermore, the substrate plane perpendicular direction refers to the direction perpendicular to the L10-type FeNi thin film plane, i.e., the LAO

[0110] direction. In other words, in Example 4, an L10-type FeNi ordered alloy thin film with high magnetic orientation was formed, which is easily magnetized in the direction parallel to the c-axis, i.e., the stacking direction of the Fe layer and Ni layer. Furthermore, in Example 4, as shown in Figure 21, the M / M phase shift was observed by applying an external magnetic field in which the c-axis in-plane parallel direction was smaller than the c-axis in-plane perpendicular direction. s The magnetic orientation at 10K was similar to that at 300K.

[0066] In Example 4, as shown in FIG. s At 300K, it is 1.36T (Tesla = Wb / m 2 ) and 1.59 T at 10 K. In Example 4, the coercive force H c The coercive force H (unit: kA / m) in the direction parallel to the c-axis plane, the direction perpendicular to the c-axis plane, and the direction perpendicular to the substrate surface were 210, 50, and 30, respectively. c was 280 in the in-plane parallel direction to the c-axis and 90 in the in-plane perpendicular direction to the c-axis. This shows that Example 4 is a tetragonal thin film structure that has a high coercive force in the in-plane parallel direction to the c-axis at both 10 K and 300 K and is excellent in magnetic orientation and coercive force characteristics.

[0067] Example 5 For Example 5, the FeNiN plane-perpendicular orientation direction and in-plane (001) orientation rate were investigated in the same manner as in Example 4. As a result, as shown in FIG. 11, in Example 5, the plane-perpendicular substrate orientation direction was (110). The in-plane (001) orientation rate was 95.5%, which was a higher (001) orientation than in Comparative Example 1. Furthermore, in Example 5, the in-plane (110) orientation rate was 100%, which, like Example 4, showed a higher (110) orientation than in Examples 1 and 2, and it was confirmed that a higher orientation, i.e., a wider single variant region, was obtained.

[0068] The magnetic properties of Example 5 were evaluated at 300 K. As a result, as shown in FIG. 23, Example 5 showed M / M when an external magnetic field was applied in which the direction parallel to the c-axis plane was smaller than the direction perpendicular to the c-axis plane. s It was found that the value of M reached a large value and saturated, and the easy axis of magnetization was in the direction parallel to the c-axis plane. From this, it was found that, in Example 5, as in Example 4, an L10 type FeNi ordered alloy thin film was formed that was easy to magnetize in the stacking direction of the Fe layer and Ni layer and had high magnetic orientation. Furthermore, in Example 5, as shown in FIG. 22, M s 1.32T, H c were 320, 60, and 90 in the direction parallel to the c-axis in-plane, the direction perpendicular to the c-axis in-plane, and the direction perpendicular to the substrate surface, respectively. This result indicates that, like Example 4, Example 5 is a tetragonal thin film structure having a high coercive force in the direction parallel to the c-axis in-plane and excellent magnetic orientation and coercive force characteristics.

[0069] The reason why Examples 4 and 5 have coercive forces equal to or greater than those of Examples 1 to 3 is thought to be because, while the tetragonal thin film 20 in Examples 1 to 3 is formed as a single continuous film, the tetragonal thin film 20 in Examples 4 and 5 has an island structure. Specifically, when an external magnetic field is applied in a direction different from the internal magnetization direction, the domain walls that are generated are less likely to move than in a continuous film due to a pinning effect caused by a nanometer-order uneven structure, making the internal magnetization less likely to change with the external magnetic field. It is presumed that the coercive force is further improved by this pinning effect of the domain walls.

[0070] Furthermore, in Examples 4 and 5, specific crystal planes such as (110) and (111) occupy a wide area of ​​the tetragonal thin film 20, and it can be said that each of the island-like structures 21 forming a group is isolated in a form close to a single crystal. Therefore, it can be said that Examples 4 and 5 have a structure in which the generation of soft magnetic phases due to amorphous structures and crystal grain boundaries near the surfaces of the island-like structures 21 is suppressed. As a result, it is thought that Examples 4 and 5 have a structure in which the proportion of soft magnetic components that serve as starting points for magnetization reversal in the tetragonal thin film 20 is reduced, and a high coercive force is obtained.

[0071] In the above, examples 4 and 5 were fabricated using LAO(110) as the support substrate 10 as a representative example, but the present invention is not limited to this. Even when a crystal structure belonging to the cubic or tetragonal system, such as STO(110) or MgO(110), is used as the support substrate 10, it is expected that a tetragonal thin film structure with the same basic structure as in examples 4 and 5 can be obtained.

[0072] (Other embodiments) Although the present disclosure has been described based on the above-described embodiment, it is not limited to the embodiment and includes various modifications and modifications within the equivalent range. In addition, it is not limited to magnetic materials, and various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

[0073] For example, in the above-described embodiment, STO(110), LAO(110), and MgO(110) were given as examples of cubic or tetragonal crystal structures constituting the support substrate 10. However, the support substrate 10 may be made of other materials. Even in such cases, the effects described in the above-described embodiment can be obtained by forming the tetragonal thin film 20 on the (110) plane as the main surface of the support substrate 10. In particular, a cubic crystal structure with an RMS mismatch difference of 1.9% or less, which is smaller than the 1.97% for STO(110), or a cubic lattice constant of 0.39 nm or less, which is smaller than 0.3905 nm, can achieve a greater reduction in variants than STO(110).

[0074] Furthermore, in the above embodiment, the support substrate 10 having a main surface with a (110) plane orientation has been described, but the entire surface of the support substrate 10 does not have to be a main surface with a (110) plane orientation. In other words, it is sufficient that at least the interface in contact with the tetragonal thin film 20 has a main surface with a (110) plane orientation.

[0075] Furthermore, in the above embodiment, a cubic crystal material having a main surface with a (110) plane orientation has been mainly described as the constituent material of the support substrate 10, but the same effect as above can be obtained even when a tetragonal crystal material is used as the constituent material.

[0076] Furthermore, in the case of a cubic sodium chloride-type crystal structure composed of two elements such as MgO, a face-centered cubic lattice is depicted as the basic unit lattice as shown in Figure 24, in order to uniformly describe it as a cubic perovskite-type crystal structure composed of three elements such as STO, rather than as the minimum unit lattice.

[0077] (Features of the present invention) [Claim 1] a support substrate (10) having at least a portion of a main surface with a (110) plane orientation and having a crystal structure belonging to a cubic or tetragonal system; a tetragonal thin film (20) formed on the main surface of the support substrate having a (110) plane orientation, the tetragonal thin film having a uniaxial in-plane orientation in a plane tangent to the main surface. [Claim 2] the support substrate has a cubic crystal structure, 2. The tetragonal thin film structure according to claim 1, wherein an RMS mismatch difference between the (110) plane orientation of the main surface of the support substrate and each of the (110) plane orientation and the (101) plane orientation of the tetragonal thin film is 1.9% or less. [Claim 3] 3. The tetragonal thin film structure according to claim 1, wherein said support substrate is made of any one of SrTiO3, LaAlO3, and MgO. [Claim 4] 4. The tetragonal thin film structure according to claim 3, wherein the support substrate is made of LaAlO3. [Claim 5] 5. The tetragonal thin film structure according to claim 1, wherein the (001) orientation rate in the plane in contact with the main surface of the tetragonal thin film is 60% or more. [Claim 6] 6. The tetragonal thin film structure according to claim 1, wherein said tetragonal thin film is a thin film of a material containing Fe, Ni, and N as elements. [Claim 7] 6. The tetragonal thin film structure according to claim 1, wherein the tetragonal thin film is a thin film of FeNiN or a thin film of an L10 type FeNi ordered alloy having an L10 type ordered structure. [Claim 8] a support substrate (10) having at least a portion of a main surface with a (110) plane orientation and having a crystal structure belonging to a cubic or tetragonal system; a tetragonal thin film (20) formed on the main surface of the support substrate having a (110) plane orientation and having a uniaxial in-plane orientation in a plane in contact with the main surface, the support substrate is made of LaAlO3, A tetragonal thin film structure, wherein the tetragonal thin film is a thin film of FeNiN or a thin film of an L10 type FeNi ordered alloy having an L10 type ordered structure. [Claim 9] 9. The tetragonal thin film structure according to claim 1, wherein the tetragonal thin film has an island structure, and at least one of the outer surfaces of each island is a {111} plane. [Explanation of symbols]

[0078] 10 Support substrate 20 Tetragonal thin film

Claims

1. A support substrate (10) having at least a portion of a main surface with a (110) plane orientation and having a crystal structure belonging to a cubic or tetragonal system; a tetragonal thin film (20) formed on the main surface of the support substrate having a (110) plane orientation and having a uniaxial in-plane orientation in a plane in contact with the main surface, the support substrate has a cubic crystal structure, A tetragonal thin film structure, wherein an RMS mismatch difference, which is a difference between the (110) plane orientation of the main surface of the support substrate and each of the (110) plane orientation and the (101) plane orientation of the tetragonal thin film, is 1.9% or less.

2. The support substrate is SrTiO ３ , LaAlO ３ 2. The tetragonal thin film structure according to claim 1, wherein the tetragonal thin film structure is composed of one of MgO and MgO.

3. The support substrate is made of LaAlO ３ 3. The tetragonal thin film structure of claim 2, comprising:

4. 2. The tetragonal thin film structure according to claim 1, wherein the (001) orientation rate in the plane contacting the main surface of the tetragonal thin film is 60% or more.

5. 2. The tetragonal thin film structure according to claim 1, wherein the tetragonal thin film is a thin film of a material containing Fe, Ni, and N as elements.

6. The tetragonal thin film is a thin film of FeNiN or L1 ０ L1 having a regular structure of type ０ 2. The tetragonal thin film structure of claim 1, which is a thin film of an ordered FeNi alloy of type ZnO.

7. 7. A tetragonal thin film structure according to claim 1, wherein the tetragonal thin film has an island structure, and at least one of the outer surfaces of each island is a {111} plane.

8. A support substrate (10) having at least a portion of a main surface with a (110) plane orientation and having a crystal structure belonging to a cubic or tetragonal system; a tetragonal thin film (20) formed on the main surface of the support substrate having a (110) plane orientation and having a uniaxial in-plane orientation in a plane in contact with the main surface, The support substrate is made of LaAlO ３ It is composed of The tetragonal thin film is a thin film of FeNiN or L1 ０ L1 having a regular structure of type ０ The tetragonal thin film structure is a thin film of an FeNi ordered alloy of the type having an island structure, and at least one of the outer surfaces of each island is a {111} plane.

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