JP5846632B2 - Oxide superconducting thin film - Google Patents

Description

The present invention relates to an oxide superconducting thin film, and more particularly to a Ba—Ca—Cu—O—F-based oxide superconducting thin film and a method for producing the same.

Since the report of a high-temperature superconductor having a high superconducting transition temperature (hereinafter referred to as “Tc”) of about 30 K in 1986, many high-temperature superconductors having a higher Tc have been reported. The structure of this high temperature superconductor tends to become more complex as Tc increases.

Examples of such a high-temperature superconductor having a complicated structure include, for example, a Tl-Ba-Ca-Cu-O-based oxide superconductor (hereinafter referred to as "Tl-based superconductor"), Hg-Ba-Ca. -Cu-O-based oxide superconductor (hereinafter referred to as "Hg-based superconductor"), Bi-Sr-Ca-Cu-O-based oxide superconductor (hereinafter referred to as "Bi-Sr-based superconductor"). Etc.) have been studied so far, and these superconductors have already been thinned.

However, Tl-based superconductors and Hg-based superconductors have a problem of containing toxic heavy metals such as Tl and Hg. In addition, Bi-Sr superconductors each contain two types of rare metals (Bi and Sr), and thus there is a problem that their availability is high.

In contrast, in recent years, Tl-based superconductors mentioned above, Hg-based superconductor or a Ba-Ca-Cu-O- F -based as the oxide superconductor conductor having a Bi-Sr-based superconductor and same high Tc An oxide superconductor has been reported. This Ba—Ca—Cu—O—F-based oxide superconductor does not contain a toxic heavy metal and has only one rare metal (Ba). Therefore, from the viewpoint of element strategy, attention is attracted as an oxide superconductor that replaces a Tl-based superconductor, an Hg-based superconductor, or a Bi—Sr-based superconductor.

Various proposals and reports have been made so far regarding the Ba—Ca—Cu—O—F-based oxide superconductor. (For example, refer nonpatent literature 1).

Akira Ito et al., “Sympressed Non-Toothic Double Ray Yard Ba2CaCu2O4 (O, F) 2 Superconductor with a Transition Temple of 108K”, Applied Physics Letters, (USA), American Institute of Physics, 2008, Vol. 92, 222501-1 to 222501-3 (A.Iyo et al., “Simplest nontoxic double-layered cuprate Ba2CaCu2O4 (O, F) 2 superconductor with a transition temperature of 108K”, Applied Physics Letters, (US), American Institute of Physics, 2008, vol.92, p222501-1 to p222501-3)

Non-Patent Document 1 discloses a bulk of a Ba—Ca—Cu—O—F-based oxide superconductor synthesized by a high-pressure method. However, the research result that the Ba—Ca—Cu—O—F-based oxide superconductor has been successfully thinned has not been reported yet. Expansion of this, Ba-Ca-Cu-O -F -based oxide super consisting conductor film, for example, a thin band-like form wire rod was deposited on the metal, or the application range of the superconductive element or the like by the film Therefore, a thin film of a Ba—Ca—Cu—O—F-based oxide superconductor is indispensable.

Then, this invention is made | formed in view of the said conventional problem, The objective is to provide the thin film of a Ba-Ca-Cu-O-F type oxide superconductor, and its manufacturing method. .

The invention of claim _{1, Ba 2 Ca n-1 Cu} n O 2n (O 1-x F x) 2 ( where, n is an integer of 2 ≦ n ≦ 5, x is 0 <x <number 1) from An oxide superconducting thin film, which is formed on any one of the (100) plane, (010) plane, and (001) plane of a single crystal substrate made of SrTiO ₃ or MgO. It is a conductive thin film.

According to the second aspect of the present invention, there is provided a Ba ₂ Ca _n-1 Cu _n O _2n ( ScTiO ₃ or MgO single crystal substrate on one of the (100), (010) and (001) planes). O _1-x F _x ) ₂ (where n is an integer satisfying 2 ≦ n ≦ 5 and x is a number satisfying 0 <x <1). Oxidation for forming a superconducting oxide thin film by a pulse laser deposition method This is a method for manufacturing a superconducting thin film.

According to a third aspect of the present invention, in the method for manufacturing an oxide superconducting thin film according to the second aspect , the method further includes a film forming step of forming a film at a substrate temperature of 700 to 770 ° C. of the single crystal substrate .

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According to the present _{invention, Ba 2 Ca n-1 Cu} n O 2n (O 1-x F x) 2 ( where, n is an integer of 2 ≦ n ≦ 5, x is 0 <x <number 1) consisting of Since the oxide superconducting thin film is formed on any one of the (100) plane, (010) plane, and (001) plane of the single crystal substrate of SrTiO ₃ or MgO, I It is possible to provide a Ba—Ca—Cu—O—F-based oxide superconductor thin film having a crystal structure of a body-centered tetragonal lattice expressed by _{4 / mmm} and having excellent superconducting properties.

Moreover, since it is the structure formed by the pulse laser deposition method, the thin film of the Ba-Ca-Cu-OF-type oxide superconductor which has the outstanding superconducting characteristic can be obtained easily.

In addition, since the formation by the pulse laser deposition method is a configuration in which the substrate temperature of the single crystal substrate is 700 ° C. to 770 ° C., the crystal structure of the body-centered square lattice represented by I _{4 / mmm} is obtained. It is possible to obtain a thin film of the Ba—Ca—Cu—O—F-based oxide superconductor having high reproducibility.

Further, (100) plane of the single crystal substrate of SrTiO ₃ or _{MgO, (010) Ba 2 Ca} n-1 on either side of the plane or the (001) plane _{Cu n O 2n (O 1-} x F _x ) ₂ (wherein n is an integer of 2 ≦ n ≦ 5 and x is a number of 0 <x <1), an oxide superconducting thin film is formed by a pulse laser deposition method. Since the manufacturing method includes a film forming process in which the single crystal substrate has a substrate temperature of 700 ° C. to 770 ° C., it has a body-centered square lattice crystal structure represented by I _{4 / mmm.} And the manufacturing method of the thin film of the Ba-Ca-Cu-OF-type oxide superconductor which has the outstanding superconducting characteristic can be provided.

It is the schematic explaining the crystal structure example of the oxide superconductor of this embodiment. It is a schematic block diagram of the thin film manufacturing apparatus of this embodiment. It is a cross-sectional schematic diagram explaining the example of the oxide superconducting thin film of this embodiment. It is a figure which shows the XRD diffraction pattern example of the oxide superconducting thin film in this embodiment. It is a figure which shows the XRD diffraction pattern example of the oxide superconducting thin film in this embodiment. It is a figure which shows the temperature dependence of the magnetic characteristic of the oxide thin film in a reference example. It is a figure which shows the temperature dependence of the magnetic characteristic of the oxide superconducting thin film in this embodiment.

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to the drawings.
First, an oxide superconductor thin film of the present embodiment, the chemical formula represented by _{Ba 2 Ca n-1 Cu n} O 2n (O 1-x F x) 2, n is an integer ranging from 2 ≦ n ≦ 5 , X is a thin film of an oxide superconductor having a composition having a number in the range of 0 <x <1.
As shown in FIG. 1, the oxide superconductor 1 has a crystal structure that forms a body-centered square lattice expressed by I _{4 / mmm} . In FIG. 1, ● represents a Ba atom, hatched ◯ represents a Cu atom, 、 represents a Ca atom, and ◯ represents an O (oxygen) atom or an F atom. A circle with a chain line indicates an atom at the apex position of a pyramid described later. In FIG. 1, reference symbols a, b, and c indicate crystal axes in the oxide superconductor 1 of the present embodiment, and are orthogonal to each other.
The main structural features of the oxide superconductor of this embodiment are as follows. As shown by reference numeral 2 in FIG. 1, O atoms around Cu atoms are coordinated in a pyramid shape. This includes points in which the O atom 3 is substituted with an F atom.

Hereinafter, for convenience of explanation, the above chemical formula is simplified, “Ba-0212” when n = 2, “Ba-0223” when n = 3, “Ba-0234” when n = 4, The case where n = 5 may be represented as “Ba-0245”.

As shown in FIG. 3, the oxide superconducting thin film 10 of the present embodiment is formed on the (100) surface 31 of the single crystal substrate 17 of SrTiO ₃ , for example. The single crystal substrate 17 is made of SrTiO ₃ single crystal and deposited on the (100) plane 31 because the lattice constant of the (100) plane of the single crystal of SrTiO ₃ depends on the oxidation of this embodiment. This is because it is close to the lattice constant of the physical superconductor 1. More specifically, this is because the a-axis and b-axis lattice constants of the oxide superconducting thin film 10 of this embodiment are close to the b-axis and c-axis lattice constants of the SrTiO ₃ single crystal substrate 17.
In addition, the shape of the single crystal substrate 17 of this embodiment is formed in the shape of a substantially square thin plate having a side length of 10 mm, for example.
Note that the single crystal substrate is not limited to SrTiO ₃ of this embodiment, and is a single crystal substrate made of MgO having a crystal plane having a lattice constant close to that of the oxide superconductor 1 of this embodiment. May be. The oxide superconducting thin film is not limited to the thin film formed on the (100) plane in this embodiment, and may be on the (010) plane or the (001) plane. This is because the crystal structure of SrTiO ₃ and MgO has cubic crystals.

The oxide superconducting thin film 10 of this embodiment is formed by a known pulsed laser deposition method (hereinafter referred to as “PLD method”).
Here, the PLD method will be briefly described with reference to FIG. FIG. 2 is a schematic configuration diagram of a thin film manufacturing apparatus 20 described later.
As shown in FIG. 2, the PLD method irradiates a focused pulse laser L onto a target 16 (to be described later) to raise the surface of the target 16 to an extremely high temperature (for example, up to several thousand degrees), thereby producing a solid material (target 16). Is vaporized and deposited as a thin film on the substrate (in the present embodiment, the single crystal substrate 17). In FIG. 2, reference symbol P indicates that particles emitted from the surface of the target 16 that has been heated to become a plasma-like light emitter called plume P.

Next, the thin film manufacturing apparatus 20 used in this embodiment will be described with reference to FIG.
As shown in FIG. 2, the thin film manufacturing apparatus 20 includes a vacuum chamber 12, a pulse laser irradiation unit 14, a substrate support unit 18 that supports the single crystal substrate 17, a substrate heating unit 21 that heats the substrate, an oxygen pressure adjusting unit 15, Crystal analysis means (not shown) and the like are provided.
As shown in FIG. 2, the vacuum chamber 12 is formed of a hermetically sealed container, in which a single crystal substrate 17 and a target 16 described later are accommodated. The vacuum chamber 12 is connected to chamber pressure adjusting means (each not shown) including, for example, a known turbo pump, rotary pump, pressure control valve, and the like, so that the pressure in the vacuum chamber 12 can be adjusted.

Next, the oxygen pressure adjusting means 15 is constituted by, for example, an oxygen introduction pipe, a mass flow controller, or the like, and can adjust the oxygen pressure of the vacuum chamber 12. In this embodiment, the oxygen gas introduced into the vacuum chamber 12 is an oxygen gas having a purity of 99.999% or more.

Next, the substrate support portion 18 includes a substrate holder 25 that holds the single crystal substrate 17 and a heat absorption plate 23.
The heat absorption plate 23 is made of, for example, a thin plate material made of Inconel having a substantially square shape with a side of 9 mm, and is disposed in close contact with the back surface of the single crystal substrate 17 as shown in FIG.
Next, the substrate holder 25 includes an Inconel frame member, for example, and holds the single crystal substrate 17 in the frame in a horizontal state, for example, as shown in FIG.
The thin film manufacturing apparatus 20 of the present embodiment includes a rotation mechanism that rotates a substrate holder 25 such as a stepping motor, for example, and an arrow M (for example, centering on an axis penetrating the central portion of the single crystal substrate 17 in the vertical direction. The single crystal substrate 17 is rotated in the direction of FIG.

Next, as shown in FIG. 2, the substrate heating unit 21 includes a known halogen lamp heater 22, a reflector 24 that reflects the heat from the halogen lamp heater 22, and a temperature control means that controls the temperature of the halogen lamp heater ( (Not shown).
As shown in FIG. 2, the halogen lamp heater 22 and the reflection plate 24 are arranged at a position slightly separated from the back surface of the heat absorption plate 23 to heat the heat absorption plate 23 and the single crystal substrate 17. Thus, the substrate heating unit 21 is configured to be able to control the temperature of the single crystal substrate 17, that is, the substrate temperature via the heat absorption plate 23. In the present embodiment, the substrate temperature is a temperature at a position approximately 7 to 8 mm apart from the back surface of the heat absorbing plate 23 in the vertical direction, and is hereinafter referred to as a substrate temperature Ts.

Further, for example, a disk-shaped target 16 is disposed at a predetermined position in the vacuum chamber 12 facing the single crystal substrate 17 and held by a target holder 26 as shown in FIG.
The thin film manufacturing apparatus 20 includes a rotating means such as a stepping motor for rotating the target holder 26, and the rotating means is opposite to the arrow M, for example, about an axis that penetrates the center of the target 16 in the vertical direction. The single crystal substrate 17 is rotated in the direction N (see FIG. 2).

Next, the pulse laser irradiation unit 14 includes, for example, a pulse laser light source that emits Nd / YAG laser light in a pulse shape. Then, as shown in FIG. 2, the pulse laser irradiation unit 14 irradiates the target 16 with a pulse laser L made of Nd · YAG laser light, for example, from the window of the vacuum chamber 12. The plume P described above is emitted by irradiating the target 16 with this pulse laser. The laser beam is not limited to the Nd / YAG laser beam of the present embodiment, and may be an excimer laser using krypton fluoride, for example.

Further, the thin film manufacturing apparatus 20 includes a shutter (not shown) that blocks particles in the plume P from reaching the single crystal substrate 17 and is configured to start epitaxial growth by opening the shutter.

Further, the crystal analysis means of the present embodiment is composed of RHEED (Reflection High Energy Electron Diffraction), which allows an electron beam to be incident on the sample surface at a shallow angle and analyze the crystal state based on the electron beam diffracted by surface atoms. It has a configuration.

In the film formation by the thin film manufacturing apparatus 20 of the present embodiment, for example, the degree of vacuum in the vacuum chamber 12 is adjusted, then the substrate temperature Ts is adjusted by the substrate heating unit 21, and then the vacuum chamber 12 is adjusted by the oxygen pressure adjusting means 15. The internal oxygen pressure is adjusted to 10 to 20 Pa (Pascal), and the target 16 is irradiated with the pulse laser L to release the plume P, and the single crystal substrate 17 and the target 16 are rotated in the opposite directions while the single crystal substrate 17 is rotated. This is done by depositing a target 16 component thereon.

Next, the target 16 of the present embodiment is produced by a direct method, and is formed into a disk shape, for example.
According to the direct method, for example, CaCO ₃ and CuO are mixed at a molar ratio of Ca: Cu = 2: 1, heated in an oxygen stream (heated at 1000 ° C. for 12 hours, pulverized once more, and further Ca ₂ CuO ₃ is produced by heating at 1000 ° C. for 12 hours). The powders of Ca ₂ CuO ₃ , CaF ₂ , BaF ₂ , CuO, and BaO ₂ are expressed as Ba: Ca: Cu: F = 2: n-1: n: 2x (integer n is 2 ≦ n ≦ 5, x is 0) <x <1) is mixed in a glove box (for example, in a nitrogen gas atmosphere that can suppress the generation of impurities by compounds other than Ba, F, and O, for example), and this mixed powder Is calcined in an oxygen atmosphere (850 to 880 ° C., about 12 hours), and the calcined product is pulverized and press-molded. And it can form by sintering (it hold | maintains at 880-920 degreeC for about 12 hours, and then gradually cools) the press-molded thing.

Note that the target is not limited to the direct method, and may be prepared by a precursor method, for example. According to this precursor method, the same Ca ₂ CuO ₃ powder and BaO ₂ , CaCO ₃ and CuO as in the direct method are mixed in Ba: Ca: Cu = 2: 2: 3 and heated in an oxygen stream. The precursor Ba ₂ Ca ₂ Cu ₃ O _Y is Ba: Ca: Cu: F = 2: n-1: n: 2x (integer n is 2 ≦ n ≦ 5, x is 0 <x <1). It can be formed by mixing in the above-mentioned glove box so as to have a molar ratio, press-molding this mixed powder, and sintering (800 to 925 ° C., about 24 hours) in an oxygen atmosphere.

Below, the Example of the oxide superconducting thin film 10 of this embodiment, a reference example, and a comparative example are demonstrated.
In the following examples, reference examples, and comparative examples, first, the target 16 was produced by a direct method as described above.
At that time, the above-mentioned Ca ₂ CuO ₃ , CaF ₂ , BaF ₂ , CuO, BaO ₂ powders are made to have a molar ratio of Ba: Ca: Cu: F = 2: 2: 3: 1.6, that is, _{Ba 2 Ca n-1 Cu n} O 2n (O 1-x F x) 2 integer n = 3, were mixed such that x = 0.8.

Next, film formation in the following examples, reference examples, and comparative examples was performed using a standard PLD apparatus manufactured by Pascal. At that time, the irradiation laser used to irradiate the target 16 was the above-described Nd / YAG laser light having a wavelength of 266 nm (Nd / YAG fourth harmonic). The irradiation conditions of the pulse laser L were such that the beam diameter was 8 mmφ, the pulse width was 2 ns or less, the shot frequency was 10 Hz, and the following fluence.
The fluence is a measurement value immediately before the focus lens installed before entering the laser viewport of the vacuum chamber 12, and ranges from 59.68 × 10 ^{−3 to} 97.48 × 10 ⁻³ J / cm ² . Of fluence. Typically, it was 59.68 × 10 ⁻³ J / cm ² . The range of the fluence is approximately 3.0 to 6.0 J / cm ² when converted on the surface of the target 16 with the transmittance of the laser light in the laser viewport being 90%. The 59.68 × 10 ⁻³ J / cm ² is 3.44 J / cm ² when converted in the same manner on the surface of the target 16.
Further, in the following examples, reference examples, and comparative examples, the time for irradiating the target 16 with the pulse laser L was about 30 minutes, and each film formation sample of about 60 nm was obtained on the single crystal substrate 17.

Examples 1-4 and reference examples will be described below.
[Example 1]
The substrate temperature Ts was adjusted to approximately 770 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to 10 Pa to obtain a film formation sample.
[Example 2]
The substrate temperature Ts was adjusted to approximately 750 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to 10 Pa to obtain a film formation sample.
[Example 3]
The substrate temperature Ts was adjusted to about 700 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to 10 Pa to obtain a film formation sample.
[Example 4]
The substrate temperature Ts was adjusted to approximately 750 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to approximately 17 Pa to obtain a film formation sample. Hereinafter, this film formation sample is referred to as P254.
[Reference example]
The substrate temperature Ts was adjusted to approximately 750 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to approximately 15 Pa to obtain a film formation sample. Hereinafter, this film formation sample is referred to as P253.

A comparative example will be described below.
[Comparative Example 1]
The substrate temperature Ts was adjusted to about 800 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to about 10 Pa to obtain a film formation sample.
[Comparative Example 2]
The substrate temperature Ts was adjusted to approximately 650 ° C., and the oxygen pressure in the vacuum chamber 12 was adjusted to approximately 10 Pa to obtain a film formation sample.

〔Evaluation results〕
The crystallinity evaluation results of Examples 1 to 4, Reference Example and Comparative Examples 1 and 2 formed as described above will be described with reference to FIGS.
FIG. 4 is a graph showing the results of XRD measurement of Examples 1 to 3 and Comparative Examples 1 and 2. In the figure, graph A is a film formation sample of Comparative Example 1, graph B is a film formation sample of Example 1, graph C is a film formation sample of Example 2, graph D is a film formation sample of Example 3, graph E is Each corresponds to the measurement result of the film formation sample of Comparative Example 2. FIG. 5A is a graph showing the result of the XRD measurement of the sample P253, and FIG. 5B is a graph showing the result of the XRD measurement of the sample P254. In FIGS. 4 and 5, the _{black circles} indicate the crystal structure of Ba-0223, that is, the peak positions appearing in the body-centered square lattice represented by I _{4 / mmm} .

According to FIG. 4, the diffraction peaks obtained from the film formation samples of Examples 1 to 3 agree very well with the peak positions appearing in the crystal structure of Ba-0223. Thus, it can be understood that the crystal structure of the film formation sample obtained in the range of Ts of 700 ° C. to 770 ° C. shows a good crystal structure as a Ba-0223 crystal.
However, the diffraction peaks of the film formation samples obtained from Comparative Examples 1 and 2 hardly show a peak that matches the peak appearing in the crystal structure of Ba-0223. Thus, it can be seen that when Ts exceeds 770 ° C., for example, 800 ° C., or below 700 ° C., for example, 650 ° C., a good crystal structure is not obtained as a Ba-0223 crystal.
As described above, the manufacturing method of the oxide superconducting thin film according to the present embodiment includes a film forming process in which the film temperature Ts of the single crystal substrate 17 is 700 ° C. to 770 ° C.

Next, according to FIG. 5 (a) and FIG. 5 (b), both P253 and P254 have observed their respective diffraction peaks at positions corresponding to the diffraction peak positions of Ba-0223, both of which are Ba−. It can be seen that the crystal structure 0223 is well formed.

Next, the magnetic characteristic evaluation results of P253 and P254 will be described with reference to FIGS. This magnetic property was measured using PPMS (Physical Property Measurement System) manufactured by Quantum Design.
FIG. 6A shows the magnetic susceptibility (magnetization) characteristics of P253 described above, and FIG. 6B shows the resistivity (resistivity) characteristics of P253. FIG. 7A shows the characteristics of P254 magnetic susceptibility, and FIG. 7B shows the characteristics of resistivity of P254.
6A and 7A, the horizontal axis represents temperature (K), and the vertical axis represents magnetic susceptibility (emu). 6B and 7B, the horizontal axis represents temperature (K), and the vertical axis represents resistivity (mΩ-cm).

In addition, in FIG. 6 (a) and FIG. 7 (a), the measured value labeled FC (Field cooled) is 5Oe outside perpendicular to the film sample of about 4 mm square (that is, perpendicular to the (100) plane). It is a measurement result at the time of cooling by applying a magnetic field. In the figure, the measured value denoted as ZFC (Zero-Field cooled) is obtained by cooling an approximately 4 mm square film formation sample in a zero magnetic field and then perpendicular to the film formation sample (that is, on the (100) plane). This is a measurement result when an external magnetic field of 5 Oe is applied to (vertical).
FIGS. 6B and 7B are measured resistivity values obtained by applying a current of 0.0001 mA to a film sample of approximately 4 mm square by the four-probe method.

According to FIG. 7B, it can be seen that the resistance value of P254 greatly decreases at 90K as a boundary. Further, according to FIG. 7A, it can be seen that the magnetic susceptibility of P254, particularly in ZFC, has changed from 90K. From this, it was found that P254 is a superconductor having a critical temperature Tc from normal to superconductivity of 90K. Thus, according to P254, a thin film of a Ba—Ca—Cu—O—F-based oxide superconductor having a critical temperature Tc as high as that of the bulk could be obtained.

Next, according to FIG. 6 (a), it can be seen that the magnetic susceptibility of P253 in ZFC changes at 55K as a boundary, but as shown in FIG. 6 (b), the resistivity decreases with temperature. It rises with. From this, it was found that P253 does not show superconducting properties.
The reason for this is that due to the difference in oxygen pressure, the substitution of O atom at the apex position in the crystal structure described above is insufficient in P253 compared to P254, or P253 is superconductive than P254. It is conceivable that the characteristics are likely to deteriorate.

As described so far, according to the oxide superconducting thin film 10 of the present embodiment, a Ba—Ca—Cu—O—F-based oxide superconductor thin film having a critical temperature Tc as high as that of the bulk is obtained. Can be provided. Moreover, according to the manufacturing method of the oxide superconducting thin film of this embodiment, the manufacturing method of the thin film of the Ba-Ca-Cu-OF-based oxide superconductor having a critical temperature Tc as high as that of the bulk is provided. Can be provided.

As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the present invention is variously modified and improved based on the knowledge of those skilled in the art. Can be implemented.

10 Oxide Superconducting Thin Film 17 Single Crystal Substrate 20 Thin Film Manufacturing Device 31 (100) Plane Ts Substrate Temperature

Claims (3)

An oxide superconducting thin film made of Ba ₂ C _n-1 C _n O _2n (O _1-x F _x ) ₂ (where n is an integer of 2 ≦ n ≦ 5 and x is a number of 0 <x <1). There,
An oxide superconducting thin film formed on any one of a (100) plane, a (010) plane, and a (001) plane of a SrTiO ₃ or MgO single crystal substrate. SrTiO ₃ Or Ba on any one of the (100) plane, (010) plane, and (001) plane of the MgO single crystal substrate. ₂ Ca _n-1 Cu _n O _2n (O _1-x F _x ) ₂ A method for producing an oxide superconducting thin film, wherein an oxide superconducting thin film is formed by a pulse laser deposition method (where n is an integer of 2 ≦ n ≦ 5 and x is a number of 0 <x <1). The method for producing an oxide superconducting thin film according to claim 2, further comprising a film forming step of forming a film at a substrate temperature of 700 to 770 ° C of the single crystal substrate.

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