JP2011068511A - Superconductive material, superconductive thin film, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductive material and a superconductive thin film having a higher superconducting transition temperature Tc which exceeds 50 K in an iron-arsenide-based superconductive material, although Tc was hitherto raised by forming a fluorine-substituted type and an oxygen defective type. <P>SOLUTION: In an iron-arsenide-based superconductive material having a crystal structure of ZrCuSiAs type, an iron-arsenide-based super conductive material represented by the chemical formula: LnFeAsO<SB>1-y</SB>H<SB>x</SB>(wherein Ln is at least one of elements chosen from the group consisting of Y and lanthanoids; y is 0 or more and 0.5 or less; and x is 0.01 or more and 0.5 or less) is provided by incorporating hydrogen. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an iron arsenic superconducting material having a high superconducting transition temperature (Tc), a superconducting thin film, and a method for producing them.

In recent years, superconducting materials aiming at room temperature superconductivity have been actively developed. Superconducting materials are used in the form of wires, thin films, and bulk materials. For example, they are used in superconducting power transmission lines, superconducting magnets (eg, linear motor cars and MRI magnets), and superconducting devices. Among them, iron-based superconductors have been reported and developed as materials for high-temperature superconductors. The iron-based superconductor is represented by the chemical formula LnFeOPh (Ln is at least one of Y and rare earth elements, Ph is at least one of P, As, and Sb), and is of the ZrCuSiAs type (space group P4 / nmm ) Is known (Patent Document 1). In Patent Document 1, a chemical formula LaFeOPh (Ph is at least one of P, As, and Sb) doped with fluorine is proposed, and the superconducting transition temperature is around 7K at LaFeO _0.94 F _0.06 As. It is described that a superconductor can be obtained.

The present inventors have developed a new superconductor (maximum Tc˜) represented by the chemical formula LnFeAsO _1-y (Ln is a lanthanoid element and Ln = La, Ce, Pr, Nd, Sm, etc., y is an oxygen deficiency rate). 54K) was developed (Non-Patent Documents 1 and 2). The new point of this substance is that the substance LnFeAsO, which has not become a superconducting material unless fluorine is used conventionally, has a high Tc of over 50 K only by depleting oxygen (1-y).

JP 2007-320829 A

Akira Ito et al., “Synthesis and Fundamental Properties of New Arsenic-Based High-Temperature Superconductors” Solid Physics, Vol. 43, no. 10, 2008, p. 53-64 Akira Ito, “High-pressure synthesis of iron-based new superconductors” High-pressure science and technology, Vol. 19, No. 2, p. 106-112

  In a conventional iron-based superconducting material (Patent Document 1), a material having a high superconducting transition temperature Tc is obtained by doping fluorine. However, since it is difficult to dope fluorine, and the stable fluorine compound LnOF tends to remain as impurities in the sample, it is difficult to synthesize a high-quality sample.

In order to obtain high Tc without doping with fluorine, the present inventors have developed an oxygen-deficient iron arsenic material (Non-Patent Documents 1 and 2). It has been found that with this LnFeAsO _1-y (Ln is a lanthanoid element and Ln = La, Ce, Pr, Nd, Sm, etc.), the crystal lattice contracts as the amount of oxygen deficiency increases, and Tc can be improved. In addition, the present inventors have found and applied for a feature on the crystal structure in which high Tc can be obtained with LnFeAsO _1-y (Japanese Patent Application No. 2008-301827).

In order to realize a crystal structure where high Tc can be obtained with LnFeAsO _1-y , it was important to shrink the crystal lattice by depleting oxygen. In order to obtain a superconducting material having a high Tc of 50K or more, it is necessary to deplete a large amount of oxygen. However, there is a problem that it becomes difficult to synthesize a sample if a large amount of oxygen is lost.

  There is a demand for an iron arsenic superconducting material capable of producing a high-quality bulk material and a thin film by a more practical method. Further, in the conventional thin film production of a material containing fluorine, there is a problem that it is difficult to produce a superconductive thin film because fluorine is difficult to enter.

  The present invention is intended to solve these problems, and provides a sintered body, a single crystal body, and a thin film by obtaining a high-quality superconducting material having a high Tc in an iron arsenic superconducting material. It is the purpose. Moreover, it aims at providing the manufacturing method for it.

  In order to achieve the above object, the present invention has the following features.

The iron arsenic superconducting material of the present invention is characterized by containing hydrogen. The iron arsenic superconducting material of the present invention is characterized by having a ZrCuSiAs type crystal structure. The iron arsenic superconducting material of the present invention preferably contains hydrogen in an oxygen deficient type, but may contain hydrogen in a parent material represented by a chemical formula LnFeAsO that is not an oxygen deficient type. Specifically, the oxygen deficient type is a substance represented by the chemical formula LnFeAsO _1-y (at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0.5 or less). is there. When y is 0, it represents a matrix material that is not substantially oxygen deficient.

The iron arsenic superconducting material of the present invention has the chemical formula LnFeAsO _1-y H _x (at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0.5 or less, and x is 0.01 or more. 0.5 or less). For example, Ln is La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, or the like.

The method of the present invention is a method for producing an iron arsenic superconducting material, characterized by containing hydrogen. The iron arsenic superconducting material in the method of the present invention has a ZrCuSiAs type crystal structure. Specifically, using a substance containing hydrogen as a starting material, the chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0) 0.5 or less, and x is 0.01 or more and 0.5 or less). Further, after synthesizing a chemical formula LnFeAsO _1-y having a ZrCuSiAs type crystal structure (where Ln is at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0.5 or less), It is characterized by containing hydrogen.

The iron arsenic superconducting thin film of the present invention is characterized by containing hydrogen. The iron arsenic superconducting thin film of the present invention is characterized by having a ZrCuSiAs type crystal structure. The method for producing an iron arsenic superconducting thin film of the present invention uses a substance containing hydrogen as a target, and has a chemical formula LnFeAsO _1-y H _x (where Ln is at least one selected from the group consisting of Y and a lanthanoid element) And a superconducting thin film represented by the following formula, wherein y is 0 or more and 0.5 or less, and x is 0.01 or more and 0.5 or less. Further, the superconducting thin film is formed using a source gas containing hydrogen. The superconducting thin film is manufactured in an atmosphere containing hydrogen gas.

  In the present invention, a high-quality superconductor was obtained by incorporating hydrogen into an iron arsenic superconductor material. By containing hydrogen, the crystal lattice can be greatly shrunk, so that a high Tc superconducting material can be obtained without losing much oxygen. In addition, since excess hydrogen that has not entered the crystal naturally comes out of the superconducting material during the manufacturing process, there is an effect that impurities in the superconducting material can be reduced.

  The iron arsenic superconducting material of the present invention is preferably an oxygen deficient type. However, even if hydrogen is contained in the chemical formula LnFeAsO which is not an oxygen deficient type, the effect can be obtained. The oxygen deficient type is preferable because hydrogen easily enters a location where oxygen is deficient, and thus has an effect of easily containing hydrogen.

In the present invention, by containing hydrogen, when Ln is La or Ce, the effect of increasing Tc is obtained as compared with the conventional fluorine substitution type and oxygen deficiency type. In addition, by adding hydrogen, when Ln is Pr, an effect of increasing Tc as compared with the conventional oxygen substitution type was obtained. Further, by containing hydrogen, a sample having higher purity than that of the conventional fluorine substitution type was obtained. That is, the effect of significantly reducing impurities was obtained by synthesizing a polycrystalline sample by actually mixing hydrogen into the raw material. By containing hydrogen, the effect of contracting the lattice is greater than when fluorine is used, so that excellent superconducting properties can be obtained. In the conventional fluorine-substituted iron arsenic superconducting material, since a raw material containing fluorine is used, a stable fluorine compound LnOF remains as an impurity in the material, which affects the superconducting properties. Since a raw material containing hydrogen is used, excess hydrogen is naturally discharged out of the material and does not remain in the material, so that there are few adverse effects due to impurities. Excess hydrogen is presumed to temporarily become Ln (OH) ₃ , but this compound decomposes at high temperatures, and is considered not to remain in the sample.

  In the present invention, since the crystal lattice can be greatly shrunk by containing hydrogen, a superconducting material having a high Tc can be produced in a high pressure synthesis at a pressure lower than that in the prior art.

  The superconducting thin film of the present invention exhibits excellent superconducting properties by containing hydrogen. Furthermore, since the lattice constant of the thin film can be greatly changed, it becomes easier to match the lattice constant of the substrate and the superconducting thin film. In addition, since the lattice constant of the thin film can be greatly changed, the choice of the substrate to be used is expanded. Therefore, the formation of a thin film, which has been difficult in the past, is facilitated by containing hydrogen.

The figure which shows the powder X-ray-diffraction pattern of the superconducting material of Example 1 of this invention. The figure which shows the relationship between the lattice constant (a-axis length) of the superconducting material (Ln = Sm) of Example 2 of this invention, and a superconducting transition temperature (Tc). The figure which shows the temperature dependence of the magnetic susceptibility of the superconducting material (Ln = La) of Example 3 of this invention.

The superconducting material of the present invention is an iron-based high-temperature superconducting material based on LnFeAsO containing hydrogen as a component of the material, and relates to LnFeAsO _1-y H _{x when} expressed by a chemical formula. Here, Ln is at least one element selected from the group consisting of Y and lanthanoid elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). Represents. Specific examples of lanthanoid elements include La, Ce, Pr, Nd, Sm, Gd, Tb, and Dy. These elements are easy to synthesize relatively good quality samples and have a high Tc. The oxygen deficiency rate y indicates the oxygen deficiency rate from the LnFeAsO crystal. y = 0 indicates that oxygen is not lost, and y = 1 indicates that there is no oxygen. 1-y indicates that oxygen is deficient. In the above chemical formula, x and y do not have to be equal. Further, the sum of (1-y) and x may be larger than 1. In this case, since the hydrogen atoms are small, there is a possibility of entering the gap between the crystals. That is, the sum of (1-y) and x may be 1 or less or 1 or more.

  In order to fabricate the superconducting material of the present invention, the superconducting properties can be dramatically improved by using hydrogen as a component of the material when synthesizing an iron-based high-temperature superconducting material using LnFeAsO as a base material. LnFeAsO which is a base material of the superconductor of the present invention has a ZrCuSiAs type crystal structure. In the present invention, by containing hydrogen, the lattice constant of the iron arsenic superconducting material is contracted to produce a superconducting material having a high Tc. Hereinafter, embodiments will be described.

(Embodiment 1)
Embodiment 1 of the present invention relates to a polycrystalline superconducting material. A hydroxide of Ln (OH) ₃ is used as a raw material for containing hydrogen in the raw material used in the production of conventional LnFeAsO. Here, Ln represents at least one of lanthanide elements. First, the raw materials LnAs, Ln (OH) ₃ , As, Fe, and Fe ₂ O ₃ are mixed at an appropriate ratio (for example, LnFeAsO _0.7 H _0.2 ). Specifically, LnAs precursor, As, Fe powder (Furuuchi Chemical, 99.9%, 100 mesh), αFe ₂ O ₃ (rare metallic, 99.9%) and Ln (OH) ₃ are mixed and mixed. Powdered. The raw materials are weighed so as to have a composition ratio of Ln: Fe: As: O: H = 1: 1: 1: (1-y): x. The amount of oxygen can be adjusted by the mixing ratio of Fe and Fe ₂ O ₃ .

  Next, the mixed powder is pressed into pellets. The pellet is heated at an appropriate temperature (about 800 ° C. to 1200 ° C.) with an appropriate pressure (1 to 50,000 atm) applied. The above high-pressure synthesis method is used. In the lanthanoid having an atomic number larger than Sm, Tc and the lattice constant are greatly dependent on the synthesis pressure. On the other hand, since Ln can be synthesized from La to Nd at a pressure of about 2 GPa, it can be synthesized even with a smaller and simpler high-pressure apparatus. Note that the synthesis method is not limited to the high-pressure synthesis method. A sealed tube method may be used.

Example 1
In Example 1, a superconducting material was synthesized using Sm as a lanthanoid. As raw materials, SmAs, Sm (OH) ₃ , As, Fe, and Fe ₂ O ₃ were mixed at an appropriate ratio. The composition ratio of the powder was adjusted so that the oxygen deficiency _{y in} SmFeAsO _1-y H _x was 0.2 and the hydrogen content x was 0.15. y represents the oxygen deficiency from the LnFeAsO crystal. The mixed powder is pressed into pellets. It heated at 1100 degreeC in the state which added 20,000 atmospheres to the pellet. A sintered body of SmFeAsO _0.8 H _0.15 was synthesized by the synthesis method as described above.

As Comparative Example 1, SmFeAsO _0.8 was synthesized by the same production method except that hydrogen was not mixed with the raw material.

FIG. 1 shows powder X-ray diffraction patterns of SmFeAsO _0.8 H _0.15 of Example 1 and SmFeAsO _0.8 of Comparative Example 1. In the SmFeAsO _0.8 (lower part of FIG. 1) of the comparative example, a peak of the impurity SmAs indicated by a black circle is seen, whereas in the SmFeAsO _0.8 H _0.15 (upper part of FIG. 1) of the impurity, It can be seen that the purity is high because there is no derived peak. Note that the black circle on the upper right in FIG. 1 is for explanation that the black circle indicates SmAs. Further, in SmFeAsO _0.8 H _0.15 (upper part of FIG. 1) of Example 1, the a-axis length of the lattice constant of the crystal lattice is 3.911Å and the c-axis length is 3.443Å. On the other hand, Comparative Example 1 containing no hydrogen has an a-axis length of 3.927 mm and a c-axis length of 3.469 mm. Thus, the lattice constant of SmFeAsO _0.8 H _0.15 of Example 1 is smaller than the lattice constant of SmFeAsO _0.8 . In addition, the superconducting transition temperature (Tc) of SmFeAsO _0.8 of Comparative Example 1 was about 40K, whereas the Tc of SmFeAsO _0.8 H _0.15 of Example 1 was about 54K.

(Example 2)
In this example, Sm was used as a lanthanoid, superconducting materials having different a-axis lengths of the lattice constant of the crystal lattice were synthesized, and the characteristics of the superconducting material were examined. As raw materials, SmAs, Sm (OH) ₃ , As, Fe, and Fe ₂ O ₃ were mixed at an appropriate ratio. The composition ratio of the raw materials was adjusted so that the oxygen deficiency _{y in} SmFeAsO _1-y H _x was 0.15 to 0.25 and the hydrogen content x was 0.1 to 0.2. Different superconducting materials were produced, and the relationship between the lattice constant a-axis length and the superconducting transition temperature (Tc) was examined. Synthesis was performed in the same manner as in Example 1.

As Comparative Example 2, SmFeAsO _1-y was synthesized by the same production method except that hydrogen was not mixed with the raw material. Superconducting materials having different a-axis lengths were produced by changing the oxygen deficiency y from 0.15 to 0.35, and the relationship between the lattice constant a-axis length and the superconducting transition temperature (Tc) was examined.

FIG. 2 shows the lattice constant a-axis length and superconducting transition temperature (Tc) of SmFeAsO _1-y H _x (black circle) of Example 2 and SmFeAsO _1-y (white circle) of Comparative Example 2 in which hydrogen is not added. Show the relationship. In SmFeAsO _1-y , the a-axis length shrinks only to 3.915 mm, whereas in SmFeAsO _1-y H _x , it shrinks greatly to 3.897 mm. This property of superconducting materials containing hydrogen is very convenient for Fe-based superconductors in which lattice contraction causes superconductivity. Moreover, as shown in FIG. 1, there was also an effect of greatly reducing SmAs impurities.

(Example 3)
In this example, La was used as the lanthanoid. LaAs, La (OH) ₃ , As, Fe, and Fe ₂ O ₃ were mixed at appropriate ratios as raw materials. The amount of the raw material powder was adjusted so that the oxygen deficiency _y in LaFeAsO _1-y H _x was 0.3 and the hydrogen content x was 0.3. The oxygen deficiency rate indicates the oxygen deficiency rate from the LaFeAsO crystal. The mixed powder is pressed into pellets. It heated at 1100 degreeC in the state which added 20,000 atmospheres to the pellet. LaFeAsO _0.7 H _0.3 was synthesized by the above high-pressure synthesis method.

As Comparative Example 3, LaFeAsO _0.7 was synthesized in the same manner except that hydrogen was not mixed with the raw material.

FIG. 3 shows a superconducting material LaFeAsO _1-y H _x (example LaFeAsO _0.7 H _0.3 ) added with hydrogen and a superconducting material LaFeAsO _1-y (example LaFeAsO _0.7 ) not added with hydrogen. The temperature dependence of magnetic susceptibility is shown. The temperature at which the magnetic susceptibility changes (indicated by an arrow in FIG. 3) is the superconducting transition temperature (Tc). In LaFeAsO _1-y , the maximum Tc is 28K, whereas in LaFeAsO _1-y H _x , it rises to 35K. This Tc is the highest record of a superconductor using LaFeAsO as a base material. Incidentally, the lattice constant (a-axis length), whereas a 4.02Å in LaFeAsO _0.7, the _LaFeAsO 0.7 _{H 0.3,} that has contracted with 3.99A, Tc increased Responsible. Thus, by adding H, the lattice contracts more greatly, so that a superconducting material having a high Tc is realized.

Example 4
In this example, Ce and Pr were used as lanthanoids instead of La in Example 3. When Ce was used as Ln, inclusion of hydrogen increased Tc from 40K to 45K as compared to oxygen deficient and fluorine substituted types. When Pr was used as Ln, the inclusion of hydrogen increased Tc from 45K to 50K compared to the oxygen deficient type.

(Embodiment 2)
The second embodiment of the present invention relates to the production of a superconducting thin film. Chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and lanthanoid elements, y is 0 or more and 0.5 or less, x is 0.01 or more and 0.5 or less) A superconducting thin film is formed. As one method for producing a superconducting thin film, a source gas containing hydrogen such as AsH ₃ is used. A film containing hydrogen is used to form a film by a vapor deposition method, a molecular beam epitaxy method, or the like. Examples of the gas containing hydrogen include a source gas containing hydrogen such as AsH ₃ and steam.

In addition, as one method for manufacturing a superconducting thin film, a target containing hydrogen as shown in Embodiment Mode 1 is prepared, and a thin film sample is manufactured by sputtering or laser ablation. Here, the target does not necessarily need to be a LnFeAsO _1-y H _x superconductor, and may be a mixture containing Ln, Fe, As, O, and H. A target is prepared so as to be LnFeAsO _1-y H _x in a state of a film finally formed.

  As a method for producing a superconducting thin film, hydrogen is contained by a method of synthesizing a thin film in an atmosphere containing hydrogen gas or a method of synthesizing a thin film and then processing in an atmosphere containing hydrogen.

  As found in Example 2 above, the property of causing lattice contraction by containing hydrogen in the iron arsenic superconducting material is similar to that of the thin film. If this is utilized, when the thin film sample is epitaxially grown on a certain crystal substrate, the lattice constant of the sample can be greatly changed, so that the lattice constant of the substrate and the sample can be easily matched. Moreover, the choice of the substrate used for thin film growth is expanded. Therefore, the formation of a thin film, which has been difficult in the past, has become easy by including hydrogen.

The above-described Embodiments 1 and 2 are typical examples. In the first embodiment, as an example of a method of synthesizing a LnFeAsO _1-y H _x superconducting material using a raw material containing H, an example using a hydroxide of Ln (OH) ₃ is shown. If it exists, hydrogen can be added and contained appropriately in an optimum form depending on the production method regardless of the form of the raw material such as solid, gas, liquid and the like.

In the LnFeAsO _1-y H _x of the present invention, if y is 0 or more and 0.5 or less and x is 0.01 or more and 0.5 or less, the property of the present invention that the lattice constant shrinks is remarkable, and Tc This is preferable because it has an effect of improving. When y is 0, oxygen is not lost. Further, it is more preferable that y is greater than 0 and 0.5 or less, since there is an effect of oxygen deficiency type. It is obvious that the present invention is not limited to y (0.2 in the first embodiment, 0.15 to 0.25 in the second embodiment, and 0.3 in the third embodiment). As is known from Non-Patent Documents 1 and 2 by the present inventors, the effect of the oxygen deficiency type is an excellent superconducting material in which the a-axis length decreases as the oxygen deficiency rate increases in the iron arsenic superconducting material. It becomes. If y is larger than 0.5, it is difficult to synthesize the substance, and the effect of improving Tc decreases. In particular, it is particularly preferable that y is in a numerical range of 0.15 or more and 0.3 or less because Tc is 50K or more (when Ln is Nd, Sm, Gd, Tb, Dy). In addition, when Ln is La, Ce, or Pr, the effect of improving Tc is greater than those that do not contain hydrogen.

  In the present invention, it is preferable that the content x of hydrogen is 0.01 or more and 0.5 or less because x has an effect of improving Tc. When x is smaller than 0.01, the effect of containing hydrogen is not sufficient as compared with the case where hydrogen is not contained. Furthermore, when x is 0.05 or more and 0.3 or less, Tc is 50K or more, which is more preferable.

  The examples shown in the embodiment and the like are described for easy understanding of the invention, and are not limited to this embodiment.

  Since the iron-based superconducting material of the present invention can be manufactured in the form of a polycrystalline body, a sintered body, a single crystal body, or a thin film, it can be used for a superconducting power transmission line, a superconducting magnet, a superconducting device, and the like. Moreover, since it has a high superconducting transition temperature and is a high-purity material, it leads to an improvement in critical current density, which is useful in application.

Claims (12)

  An iron arsenic superconducting material characterized by containing hydrogen.   2. The iron arsenic superconducting material according to claim 1, which has a ZrCuSiAs type crystal structure. ZrCuSiAs type crystal structure, chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and lanthanoid elements, y is 0 or more and 0.5 or less, x is 0 .01 or more and 0.5 or less), an iron arsenic superconducting material.   A method for producing an iron arsenic superconducting material, wherein hydrogen is contained in the method for producing an iron arsenic superconducting material.   5. The method of manufacturing an iron arsenic superconducting material according to claim 4, wherein the iron arsenic superconducting material has a ZrCuSiAs type crystal structure. Using a substance containing hydrogen as a starting material, it has a ZrCuSiAs type crystal structure, and has a chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and a lanthanoid element, y Is a superconducting material represented by 0 to 0.5 and x is 0.01 to 0.5), a method for producing an iron arsenic superconducting material. After synthesizing a chemical formula LnFeAsO _1-y having a ZrCuSiAs type crystal structure (where Ln is at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0.5 or less), And the chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and lanthanoid elements, y is 0 or more and 0.5 or less, and x is 0.01 or more and 0.00. 5 or less) is produced. A method for producing an iron arsenic superconducting material, characterized by comprising:   An iron arsenic superconducting thin film characterized by containing hydrogen.   9. The iron arsenic superconducting thin film according to claim 8, which has a ZrCuSiAs type crystal structure. Using a substance containing hydrogen as a target, the chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and lanthanoid elements, y is 0 or more and 0.5 or less, x Is a superconducting thin film expressed by 0.01 to 0.5), and a method for producing an iron arsenic superconducting thin film. Using a source gas containing hydrogen, the chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and a lanthanoid element, y is 0 or more and 0.5 or less, x is 0 A method for producing an iron arsenic superconducting thin film, characterized in that a superconducting thin film represented by .01 or more and 0.5 or less is formed. In an atmosphere containing hydrogen gas, the chemical formula LnFeAsO _1-y H _x (where Ln is at least one element selected from the group consisting of Y and lanthanoid elements, y is 0 or more and 0.5 or less, and x is 0.5. A method for producing an iron arsenic superconducting thin film, characterized in that a superconducting thin film represented by (01) to (0.5) is produced.

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