JP4559720B2 - Oxide superconducting thin film and manufacturing method thereof - Google Patents

Description

  The present invention relates to an oxide-based superconducting thin film used for a superconducting wire or a superconducting filter, and a method for producing the same.

Oxide superconductors as represented by Y-Ba-Cu-O system, in order to show a high critical temperature T _C than the temperature of liquid nitrogen (77K), its application to superconducting wire and the superconducting filter is expected ing. When such an oxide-based superconductor is applied to a superconducting wire or a superconducting filter, it is necessary to improve the critical current density _JC . In addition, in order to prevent a decrease in critical current density in a magnetic field, it is necessary to introduce a pinning point in the superconductor.

  Under such circumstances, in the Y—Ba—Cu—O-based oxide superconducting thin film, a method using a Cu—O precipitate as a pinning point is considered (see Non-Patent Document 1). However, it is difficult to uniformly distribute such pinning points in the superconductor.

In addition, a plate in which the c-axis plane of the crystal of the oxide superconducting thin film on the substrate is arranged in parallel with the thin-film formation surface of the substrate and the c-axis plane of the crystal is arranged perpendicular to the thin-film formation surface of the substrate There is also a method of using a phase as a pinning point (see Non-Patent Document 2). However, in this method, when the film thickness is increased, the pinning point interrupts the current path, so that the critical current density _JC is considered to decrease.

H. Yamane, et al., J. Appl. Phys., Vol. 69, No. 11, 1991, pp. 7948-7950 H. Fuke et al., Appl. Phys. Lett., Vol.60, No.21, 1992, pp.2686-2688

  As described above, examples of improving the critical current density of oxide-based superconducting thin films have been reported, but when applying oxide-based superconducting thin films to superconducting wires and superconducting filters, the critical current value is reported. In addition, the critical current value per unit width of the thin film (unit A / 1 cm-width representing the critical current value per 1 cm width is often used for superconducting wire evaluation) needs to be increased. For this purpose, it is necessary to increase the thickness of the thin film without reducing the critical current density.

  In order to solve these problems, the present invention does not deteriorate the critical current density characteristics even when the oxide-based superconducting thin film is thickened, and has a large critical current value per unit width in a magnetic field. The object is to provide a physical superconducting thin film.

The superconducting thin film according to the first aspect of the present invention includes a substrate and a superconducting laminate formed on the substrate and composed of a plurality of superconductor layers, and each of the plurality of superconductor layers includes have a different defect density, the superconductor layer of said plurality of a first superconductor layer in contact with the substrate, and a second superconductor layer formed on the first superconductor layer In addition, the first superconductor layer is formed at a substrate temperature that is at least 50 ° C. higher than the substrate temperature when forming the second superconductor layer . Each of the plurality of superconductor layers has a crystal c-axis perpendicular to the substrate surface, and RE _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (wherein RE is La, Nd, Sm, Eu, Gd, It is selected from the group consisting of Y and Yb, and x may be 0 to 0.2, and y may be 0 to 2). The defect density of the first superconductor layer is preferably smaller than the defect density of the second superconductor layer.

  The method for producing a superconducting thin film according to the second aspect of the present invention is a method for producing a superconducting thin film by laminating a superconducting laminate composed of a plurality of superconductor layers on a substrate, Forming at least a first superconductor layer on the substrate and forming a second superconductor layer on the first superconductor layer; and forming the first superconductor layer. The substrate temperature at that time is at least 50 ° C. higher than the substrate temperature at the time of forming the second superconductor layer. Here, it is desirable that the defect density of the first superconductor layer is smaller than the defect density of the second superconductor layer. In addition, the step of forming the first superconductor layer and the step of forming the second superconductor layer include a substrate at 680 ° C. or higher in an atmosphere having an oxygen partial pressure of 0.1 Torr (13.3 Pa) or higher. It may be performed using physical vapor deposition or chemical vapor deposition at temperature.

  Another embodiment of the present invention is a superconducting superconducting wire or a superconducting device using the superconducting thin film of the first embodiment. Yet another aspect of the present invention is a method for manufacturing a superconducting wire or a superconducting device using the method for manufacturing a superconducting thin film of the second aspect.

  According to the present invention, the critical current characteristics of the oxide-based superconducting thin film can suppress deterioration in a magnetic field, and the oxide superconducting thin film and the superconducting wire having a large critical current value per unit width in the magnetic field. It is possible to provide a superconducting system and a superconducting device.

  An exemplary configuration of the superconducting thin film of the present invention is shown in FIG. The superconducting thin film of FIG. 1 has a structure in which a superconducting laminate is formed on a substrate 1, and the superconducting laminate is formed of a first superconductor layer 2 and a second superconductor layer 3. Yes.

As the substrate 1 of the present invention, perovskite crystals such as SrTiO ₃ and LaAlO ₃ ; rock salt crystals such as MgO and NiO; spinel crystals such as MgAl ₂ O ₄ ; fluorite crystals such as yttrium-stabilized zirconia and CeO ₂ A rare earth C-type crystal; an oxide such as a Pikuroa-type crystal; and a metal substrate (a Ni-based alloy substrate such as pure Ni, Ni-Cr and Ni-W, a Cu-based alloy substrate such as pure Cu and Cu-Ni, or Fe) -Fe-based alloy substrates such as Si and stainless steel) can be used. Alternatively, the substrate 1 may be the above-described oxide substrate, the above-described metal substrate, nitride substrate, or semiconductor substrate on which a buffer layer made of the above-described oxide or boride (such as MgB ₂ ) is formed. . More preferred substrates include MgO substrates, metal substrates, and metal substrates coated with oxides. In particular, it is advantageous to use a long metal substrate covered with an oxide when forming a superconducting wire. The material for forming the substrate 1 is not particularly limited, but desirably has a lattice constant close to that of the oxide-based superconductive material forming the superconductor layer.

Each superconductor layer constituting the superconducting laminate of the present invention is formed from an oxide-based superconducting material, which has the chemical formula RE _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (where RE is La, Nd, Sm, Eu, Gd, Y or Yb, x is 0 to 0.2, and y is 0 to 2), and is an oxide-based superconducting material containing rare earth (RE). .

  The superconducting laminate of the present invention is provided in contact with the substrate 1 and is provided on the first superconductor layer 2 having a lower defect density and the first superconductor layer, and has a higher defect density. And at least a second superconductor layer 3. The superconducting laminate of the present invention is composed of three or more layers, provided that the defect density of the first layer provided in contact with the substrate is smaller than the defect density of the second layer provided thereon. May be. In addition, each superconductor layer constituting the superconductor layer of the present invention has a different defect density. These superconductor layers may be formed of the same oxide superconducting material or may be formed of different oxide superconducting materials. The superconducting laminate formed from two layers will be described in detail below.

  The first superconductor layer 2 is a layer of an oxide-based superconducting material provided in contact with the substrate 1 and having a smaller defect density. In addition, since the superconducting material forming the first superconductor layer 2 is c-axis oriented (the c-axis is perpendicular to the substrate surface), the ab surface which is the superconducting surface is parallel to the substrate. Thus, a large current can flow in a direction parallel to the substrate. In addition, the first superconductor layer 2 is also c-axis oriented so that the layers formed thereon (the second superconductor layer 3 or each of the two or more superconductor layers) are c-axis oriented. It is important that

  The first superconductor layer 2 is formed by physical vapor deposition such as laser vapor deposition or sputtering vapor deposition, or chemical vapor deposition such as organic chemical vapor deposition, preferably pulsed laser vapor deposition (PLD), organometallic. It can be formed using chemical vapor deposition (MOCVD). PLD is a desirable formation method in that the average composition (replacement amount value x) of RE and Ba is controlled because the composition ratio of the target is reflected in the composition ratio of the thin film to be formed. The “average composition” in the present invention means that the composition of a part of the layer may fluctuate, but the whole layer has a specified composition. When each superconductor layer constituting the superconducting laminate of the present invention is laminated by the PLD method, a target obtained by mixing and sintering a metal oxide forming the superconductor layer in a desired ratio Can be used. As the laser for irradiating the target, any laser known in the art, such as an Ar—F excimer laser, can be used.

  In addition, since MOCVD can control the composition of the thin film formed by controlling the flow rate of the source gas, it controls the average composition (replacement value x) of RE and Ba in the same manner as PLD. Is a desirable formation method. When each superconductor layer constituting the superconducting laminate of the present invention is laminated by MOCVD, the source gas is known in the art, such as a metal complex, alkoxide, or alkylated substance constituting the superconductor layer. Any material can be used. At this time, the holding (vaporization) temperature of the source gas can be controlled, and the flow rate (partial pressure) of each source gas can be set to form a superconductor layer having a desired composition. When the first superconductor layer 2 is formed, a high substrate is used to obtain a superconductor thin film having a smaller defect density and c-axis orientation (c-axis is perpendicular to the substrate surface). It is desirable to use temperature (800-900 degreeC). Preferably, a substrate temperature of 800-850 ° C. for PLD and 800-900 ° C. for MOCVD is used. In order to keep the composition ratio of oxygen in the superconductor material within a desired range, PLD and MOCVD are performed in an oxygen atmosphere. It is desirable that the oxygen partial pressure be 0.1 Torr (13.3 Pa) or more.

The term “defect” in this specification is not recognized in the state in which the superconductor material is laminated, but holes (pits) are formed when the surface of the layer is etched with an etchant (such as Br ₂ -MeOH). It means the part. The existence of defects and the density per unit area can be confirmed or measured using a detection means such as an atomic force microscope (AFM) or a transmission electron microscope (TEM). Defects in the superconductor layer function as pinning points for the quantized magnetic flux that penetrates into the superconductor stack when a magnetic field is applied. The defect in the first superconductor layer 2 formed by the above-described method has a fine size on the order of nm, and therefore does not inhibit the current flowing in the layer parallel to the substrate. Therefore, the superconducting thin film of the present invention is useful when used as a superconductor device such as a superconducting wire or a superconducting filter. The density of defects in the first superconductor layer 2 is controlled by the material of the superconductor layer, the material of the substrate 1, the substrate temperature during film formation, and the oxygen partial pressure. The desired defect density depends on the intended application, but can be, for example, on the order of about 10 in a 1 μm square area.

  As described above, the first superconductor layer 2 desirably has a film thickness sufficient for the c-axis orientation of the first superconductor layer 2 and the c-axis orientation of the superconductor layer formed thereon. The first superconductor layer 2 preferably has a film thickness of preferably 100 nm or less, more preferably in the range of 30 nm to 50 nm.

  The second superconductor layer 3 is a layer of an oxide-based superconducting material provided on the first superconductor layer 2 in contact with the layer and having a higher defect density. Also, the superconducting material forming the second superconductor layer 3 is c-axis oriented by the action of the first superconductor layer 2. Therefore, the ab surface, which is a superconducting surface, is parallel to the substrate, and a large current can flow in the direction parallel to the substrate.

  As with the first superconductor layer 2, the second superconductor layer 3 is preferably a physical vapor deposition method such as laser vapor deposition or sputtering vapor deposition, or a chemical vapor deposition method such as organic chemical vapor deposition. Can be formed using pulsed laser deposition (PLD) or metal organic chemical vapor deposition (MOCVD). The target and laser used for PLD and the source gas used for MOCVD can be the same as those used for the first superconductor layer 2. However, when forming the second superconductor layer 3, in order to obtain a superconductor thin film having a larger defect density, a substrate temperature lower by at least 50 ° C. than the formation temperature of the first superconductor layer 2 is used. It is desirable to use it. The second superconductor layer 3 is usually at a substrate temperature of 680 ° C. or higher, preferably within a range of 730-780 ° C., more preferably at a substrate temperature of 730-780 ° C. in the case of PLD, in the case of MOCVD. Is formed at a substrate temperature of 730-780 ° C. In order to keep the composition ratio of oxygen in the superconductor material within a desired range, PLD and MOCVD are performed in an oxygen atmosphere. It is desirable that the oxygen partial pressure be 0.1 Torr (13.3 Pa) or more.

  The relationship between the substrate temperature during film formation of the second superconductor layer 3 and the defect density in the second superconductor layer 3 when the substrate temperature during film formation of the first superconductor layer 2 is 830 ° C. As shown in FIG. As is apparent from FIG. 4, it is understood that the defect density is remarkably increased when a substrate temperature of 780 ° C. or lower is used. Therefore, it has been confirmed that a substrate temperature difference of at least 50 ° C. is necessary to greatly increase the density (amount) of defects.

  It is considered that fine stacking faults crystallize inside the oxide-based superconducting layer produced at the substrate temperature as described above, and that the defects function as a pinning point of the quantized magnetic flux. As in the case of the first superconductor layer 2, the defects in the second superconductor layer 3 formed by the above-described method have a size on the order of nm, so that a current flowing in the layer parallel to the substrate is generated. It is useful when the superconducting thin film of the present invention is used as a superconductor device such as a superconducting wire or a superconducting filter. The density of defects in the second superconductor layer 3 is controlled by the material of the superconductor layer, the material of the substrate 1, the substrate temperature during film formation, and the oxygen partial pressure. The desired defect density depends on the intended application, but can be, for example, about 30 in a 1 μm square area.

  It is desirable that the second superconductor layer 3 has a film thickness sufficient to pass a desired amount of current. The second superconductor layer 3 preferably has a film thickness of preferably 300 nm or more, more preferably 300 nm to 3.0 μm.

  The total film thickness of the superconducting laminate (the total film thickness of the first superconductor layer 2 and the second superconductor layer, or the total film thickness when three or more superconductor layers are used) is generally Although it is 0.7-2.0 micrometers specifically, in a specific use, you may enlarge the whole film thickness.

Example 1
A superconducting thin film in which an Sm—Ba—Cu—O-based oxide superconducting laminate was laminated on an MgO substrate was produced by the PLD method.

First, an excimer laser is irradiated to a target of Sm _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (x = 0, 0.04, 0.08, 0.12), and a first film having a thickness of 10 nm is formed on the MgO substrate. A superconductor layer was laminated. At this time, the substrate temperature was set to 800 to 850 ° C., and the oxygen partial pressure in the vacuum chamber was set to 0.4 Torr (53 Pa).

When the first superconductor layer formed of the obtained Sm—Ba—Cu—O-based oxide was examined, the c-axis of the oxide crystal was perpendicular to the film formation surface of the substrate. Was confirmed. Further, the obtained first superconductor layer was etched using Br ₂ -MeOH (0.166 vol%), and the surface was observed with AFM. As a result, a surface observation image as shown in FIG. 2 was confirmed. From this result, it was confirmed that the first superconductor layer had a defect density of about 10 / μm ² . Moreover, it is confirmed from the micro structure observation by TEM that these stacking faults are crystallized.

Next, an excimer laser is irradiated to a target of Sm _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (x = 0, 0.04, 0.08, 0.12), and a film thickness is formed on the first superconductor layer. A second superconductor layer of 500 nm was laminated. At this time, the substrate temperature was set to 700 to 800 ° C., and the oxygen partial pressure in the vacuum chamber was set to 0.4 Torr (53 Pa).

As in the case of the first superconductor layer, when the second superconductor layer formed of the obtained Sm—Ba—Cu—O-based oxide was examined, the c-axis of the oxide crystal was It was confirmed that the first superconductor layer was perpendicular to the film formation surface (that is, the film formation surface of the substrate). The second superconductor layer is etched using the _Br 2 -MeOH (0.166% by volume) still obtained, as a result of surface observation with AFM, the surface observation image as shown in FIG. 3 was confirmed. From this result, it was confirmed that the second superconductor layer had a defect density of about 30 / μm ² . Moreover, it is confirmed from the micro structure observation by TEM that these defects are crystallized.

Examination of the superconducting critical temperature T _C superconducting thin film obtained by the above method, it was confirmed that not less than 90K. Further, the critical current density J _C did not decrease, and J _C = 2 to 4 × 10 ⁶ A / cm ² (x = 0, 0.04) was obtained at a temperature of 77K. Furthermore, Jc measurement of the superconducting thin film in a magnetic field was performed. The magnetic field was applied perpendicular to the film surface, that is, parallel to the c-axis direction of the crystal. As a result, a large critical current density of Jc = 3 × 10 ⁵ A / cm ² (when x = 0.04) was obtained in an applied magnetic field of 5 T (Tesla) at a temperature of 77 K. It was revealed that the thin film has excellent superconducting properties.

Further, it has been clarified that the critical current density _JC does not decrease even when the film thickness is increased in the film in which the target composition ratio x is increased. On the first superconductor layer formed in the same manner as described above, Sm _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (x = 0.08, 0.12) was used as a target, and a _second film with a thickness of 1.1 μm was used. A superconductor layer 3 was formed. Of superconducting thin films obtained, the critical current value _{I C} per 1cm width used in the evaluation of a superconducting material at a temperature 77K, was 400~483A / 1cm-width. As for the maximum value of I _C , when a target having a composition of x = 0.08 was used, a high critical current value of I _C = 483 A / 1 cm-width was obtained.

(Comparative Example 1)
A superconducting thin film in which a single-layer Sm—Ba—Cu—O-based oxide superconductor layer was laminated on an MgO substrate by the PLD method was produced.

A target of Sm _{1 + x} Ba _2−x Cu ₃ O _{6 + y} (x = 0, 0.04, 0.08, 0.12) is irradiated with an excimer laser, and a superconductor layer having a thickness of 500 nm is formed on the MgO substrate. Laminated. At this time, the substrate temperature was set to 790 to 850 ° C., and the oxygen partial pressure in the vacuum chamber was set to 0.4 Torr (53 Pa).

When the superconductor layer formed of the obtained Sm—Ba—Cu—O-based oxide was examined, it was confirmed that the c-axis of the oxide crystal was perpendicular to the film formation surface of the substrate. It was done. Further, the obtained superconductor layer was etched using Br ₂ -MeOH (0.166 vol%), and the surface was observed with AFM. As a result, the superconductor layer had a defect density of about 10 / μm ^2. It was confirmed. Moreover, it is confirmed from the micro structure observation by TEM that these stacking faults are crystallized.

Examination of the superconducting critical temperature T _C superconducting thin film obtained by the above method, it was confirmed that not less than 90K. Further, the critical current density J _C did not decrease, and J _C = 2 to 4 × 10 ⁶ A / cm ² (x = 0, 0.04) was obtained at a temperature of 77K. Furthermore, Jc measurement of the superconducting thin film in a magnetic field was performed. The magnetic field was applied perpendicular to the film surface, that is, parallel to the c-axis direction of the crystal. As a result, it became clear that the critical current density decreased to Jc = 4 × 10 ⁴ A / cm ² (when x = 0.04) in a 5 T applied magnetic field at a temperature of 77 K.

  As described above, the superconducting thin film of Comparative Example 1 shows a critical current density equivalent to that of the superconducting thin film of Example 1 when no magnetic field is applied, but the critical current density is significantly reduced when a magnetic field is applied. I understand that. This result is considered to be due to the fact that a sufficient amount of pinning points are not introduced in the superconducting thin film of Comparative Example 1 composed of a single layer.

(Example 2)
A superconducting thin film in which an Nd—Ba—Cu—O-based oxide superconducting laminate was laminated on an SrTiO ₃ substrate was produced by MOCVD.

First, Nd (DPM) ₃ , Ba (DPM) ₂ and Cu (DPM) ₂ (where DPM is dipivaloylmethane) are used on the SrTiO ₃ substrate as the organic metal (MO) raw material. The 1st superconductor layer which has a film thickness of about 10 nm was laminated | stacked. At this time, the holding temperatures of the respective MO raw materials were 125 ° C., 240 ° C. and 120 ° C. The substrate temperature was set to 800 to 850 ° C., and the oxygen partial pressure in the vacuum chamber was set to 3 Torr (0.40 kPa).

When the first superconductor layer formed of the obtained Nd—Ba—Cu—O-based oxide was examined, the c-axis of the oxide crystal was perpendicular to the film formation surface of the substrate. Was confirmed. Further, the obtained first superconductor layer was etched using Br ₂ -MeOH (0.166% by volume), and the surface was observed with AFM. As a result, the number of first superconductor layers was about 7 / μm ² . It was confirmed to have a density. Moreover, it is confirmed from the micro structure observation by TEM that these stacking faults are crystallized.

Next, Nd (DPM) ₃ , Ba (DPM) ₂ and Cu (DPM) ₂ are used as the organic metal (MO) raw material, and the second superconductor having a thickness of about 500 nm is formed on the first superconductor layer. The body layer was laminated. At this time, the holding temperatures of the respective MO raw materials were 125 ° C., 240 ° C. and 120 ° C. The substrate temperature was set to 700 to 800 ° C., and the oxygen partial pressure in the vacuum chamber was set to 0.4 Torr (53 Pa). This substrate temperature was set at a temperature lower by at least 100 ° C. than the substrate temperature of the oxide-based superconducting layer with many stacking faults.

As in the case of the first superconductor layer, when the second superconductor layer formed of the obtained Nd—Ba—Cu—O-based oxide was examined, the c-axis of the oxide crystal was It was confirmed that the first superconductor layer was perpendicular to the film formation surface (that is, the film formation surface of the substrate). Further, the obtained second superconductor layer was etched using Br ₂ -MeOH (0.166% by volume), and the surface was observed with AFM. As a result, the number of second superconductor layers was about 20 / μm ² . It was confirmed to have a density. Moreover, it is confirmed from the micro structure observation by TEM that these stacking faults are crystallized.

Examination of the superconducting critical temperature T _C superconducting thin film obtained by the above method, it was confirmed that not less than 90K. Further, the critical current density J _C did not decrease, and J _C = 1 × 10 ⁶ A / cm ² was obtained at a temperature of 77K. Furthermore, Jc measurement of the superconducting thin film in a magnetic field was performed. The magnetic field was applied perpendicular to the film surface, that is, parallel to the c-axis direction of the crystal. As a result, a large critical current density of Jc = 1.2 × 10 ⁵ A / cm ² was obtained in an applied magnetic field of 5 T (Tesla) at a temperature of 77 K, and the superconducting thin film of this example had excellent superconducting properties. It became clear to have.

It is sectional drawing which shows the exemplary structure of the superconducting thin film of this invention. FIG. 4 is a view showing a surface observation image (1 μm × 1 μm) by AFM of the first superconductor layer obtained in Example 1. It is a figure which shows the surface observation image (1 micrometer x 1 micrometer) by AFM of the 2nd superconductor layer obtained in Example 1. FIG. It is a graph which shows the relationship between the film formation substrate temperature of a 2nd superconductor layer, and the defect density in a 2nd superconductor layer when the film formation substrate temperature of a 1st superconductor layer is made constant at 830 degreeC. .

Explanation of symbols

1 Substrate 2 First Superconductor Layer 3 Second Superconductor Layer 4 Defect 5 Defect Confirmed by Etching

Claims (10)

A plurality of superconductor layers formed on the substrate and composed of a plurality of superconductor layers, each of the plurality of superconductor layers having a different defect density ; Each of RE _{1 + x} Ba _2−x Cu ₃ O _{6 + y} , wherein RE is selected from the group consisting of La, Nd, Sm, Eu, Gd, Y and Yb, and x is 0 to 0.2, y is 0 to 2), and each of the plurality of superconductor layers is formed using physical vapor deposition or chemical vapor deposition, and the plurality of superconductivity layers The body layer includes a first superconductor layer in contact with the substrate and a second superconductor layer formed on the first superconductor layer, and forms the first superconductor layer. The substrate temperature at the time is 800-850 ° C., and the substrate temperature at the time of forming the second superconductor layer is 700-800. Superconducting thin film characterized in that it.   2. The superconducting thin film according to claim 1, wherein each of the plurality of superconductor layers has a c-axis of a crystal perpendicular to a substrate surface.   The superconducting thin film according to claim 1 or 2, wherein the defect density of the first superconductor layer is smaller than the defect density of the second superconductor layer. A method of manufacturing a superconducting thin film by laminating a superconducting laminate composed of a plurality of superconductor layers on a substrate,
Forming a first superconductor layer on a substrate using physical vapor deposition or chemical vapor deposition ;
Forming a second superconductor layer on the first superconductor layer using physical vapor deposition or chemical vapor deposition , and each of the plurality of superconductor layers includes: , RE _{1 + x} Ba _2−x Cu ₃ O _{6 + y where} RE is selected from the group consisting of La, Nd, Sm, Eu, Gd, Y and Yb, x is 0 to 0.2, and y is 0 The substrate temperature when forming the first superconductor layer is 800 to 850 ° C., and the substrate temperature when forming the second superconductor layer is 700. A method for producing a superconducting thin film, characterized in that it is -800 ° C.   5. The method of manufacturing a superconducting thin film according to claim 4, wherein the defect density of the first superconductor layer is smaller than the defect density of the second superconductor layer. Forming a step and the second superconductor layer to form said first superconductor layer, and characterized in that it is carried out in an atmosphere having 0.1 Torr (13.3 Pa) or more oxygen partial pressure The method for producing a superconducting thin film according to claim 4 or 5.   A superconducting wire comprising the superconducting thin film according to any one of claims 1 to 3.   A superconducting device using the superconducting thin film according to any one of claims 1 to 3. A method for producing a superconducting wire, wherein the method for producing a superconducting thin film according to any one of claims 4 to 8 is used. A method for producing a superconducting device, wherein the method for producing an oxide-based superconducting thin film according to any one of claims 4 to 8 is used.

Images