JPH0781934A - Superconductor and production thereof - Google Patents

Abstract

PURPOSE:To produce an electronic copper-contg. multiple oxide superconductor excellent in superconducting characteristics with a high reproducibility. CONSTITUTION:This superconductor is represented by formula I (where M is Ga and/or Al, 0<=alpha<=1, 0.9<=beta<=1.1, 0<=gamma<=0.20, 0<=delta<=0.25 and 0<=epsilon<=0.04 but gamma and delta are not simultaneously 0) and it is produced by accumulating atomic layers of an oxide represented by formula II and atomic layers of an oxide represented by formula III in layers.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a fusion reactor, a magnetohydrodynamic generator, an accelerator, a rotating electric device (motor, generator, etc.), a magnetic separator, a magnetic levitation train, a nuclear magnetic resonance measuring device, a magnetic propulsion ship. , Suitable as a material for magnet coil of electron beam exposure equipment, various experimental equipment, etc., and also suitable for applications such as power transmission line, electric energy storage, transformer, rectifier, phaser where power loss is a problem. Josephson element, SQUI
The present invention relates to a superconductor suitable as an element such as a D element and a superconducting transistor, and further as a functional material such as an infrared detection material and a magnetic shielding material.

[0002]

2. Description of the Related Art A series of copper complex oxide superconductors is classified into two types, that is, a hole type superconductor in which holes function as charge carriers and an electron type superconductor in which electrons function as charge carriers. . And, these copper complex oxide superconductors,
The amount of charge carriers doped in the crystal, especially Cu-
It is known that the superconducting transition temperature (hereinafter referred to as Tc) changes depending on the amount of charge carriers per O ₂ surface layer (hereinafter referred to as carrier concentration). In that case, when the carrier concentration is in the range of 0.05 to 0.32, superconducting properties are exhibited, and particularly, when the carrier concentration is 0.12 to 0.23.
In the range of, Tc shows the maximum value.

Also, the carrier concentration is within the above range,
And regarding the hole-based superconductor having holes as charge carriers,
The empirical rule holds that as the minimum unit defined in the crystallographically defined c-axis direction, that is, as the number of Cu—O ₂ planes present in the unit cell increases, its Tc also increases.
For example, having three layers of Cu—O ₂ planes in the unit cell,
So-called three-layer superconductor Tl ₂ Ba ₂ Ca ₂ Cu
_In the case of ₃ O ₁₀ , its Tc shows a value of 125K. However, in the case of the hole-based superconductor, there is a problem that it is difficult to manufacture it as an element because of its short coherence length, and the element operation is not good.

On the other hand, an electron-based superconductor having electrons as charge carriers has a long coherence length and is said to be highly suitable for device manufacturing. The following oxides are known as such electronic superconductors. For example, "Nature", Vol. 337, p. 345 (1989).
1) proposed an oxide superconductor in which an oxide having a composition of Nd _1.85 Ce _0.15 CuO _4-y was doped with electrons as charge carriers. However, the Tc of this superconductor is about 24K, which is considerably low.

Also, "Nature", Volumes 351, 541
The page (1991) shows that the composition is (Sr, Nd) CuO.₂
And (Sr, La) CuO₂Dope an oxide with an electron
The oxide superconductor has been proposed. Of this superconductor
Tc is about 40K. However, this superconductor
Contains Nd and La as ingredients,
Stable Nd₂CuO_FourPhase and La ₂CuO_FourCreate a phase
Frequently occurs, and as a result, Tc is not
It is difficult to raise even more.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems in electronic superconductors, to provide a superconductor having a controlled carrier concentration and a high Tc, and a method for producing the same. It is to be.

[0007]

In order to achieve the above object, in the present invention, the following formula: (Ca _1- αSrα) β (Cu _1- γMγ) (O _1- δFδ)
_2- ε (In the formula, M represents Ga or / and Al, and α, β,
γ, δ and ε are 0 ≦ α ≦ 1 and 0.9 ≦ β ≦ 1 respectively.
1, 0 ≤ γ ≤ 0.20, 0 ≤ δ ≤ 0.25, 0 ≤ ε ≤ 0.04
Represents the number that satisfies. However, γ and δ cannot be 0 at the same time), and a superconducting method is used, and the following formula is used: (Ca _1- αSrα) β (1) (In the formula, α and β are 0 ≦ α ≦ 1 and 0.9 ≦ β ≦, respectively.
A metal atomic layer represented by the formula ( ₁ ) is formed on the metal atomic layer and the stacking method is used to form the following formula: (Cu _1- γMr) (O _1- δFδ) _{2 - ε} ... (2) (wherein, M represents Ga or / and Al, γ, δ,
ε is 0 ≦ γ ≦ 0.20, 0 ≦ δ ≦ 0.25,0, respectively.
Represents a number that satisfies ≦ ε ≦ 0.04. However, there is provided a method for producing a superconductor characterized by repeating an operation of forming a copper oxide layer represented by (γ and δ do not become 0 at the same time).

The superconductor of the present invention comprises at least one layer of formula
A layer of metal atoms represented by (1) and at least one layer of formula
It is a layered oxide in which the oxide layers represented by (2) are alternately laminated infinitely. The oxide layer represented by the formula (2) has a basic composition of Cu—O ₂ , in which a part of Cu is replaced with M (Ga or / and Al), and a part of oxygen is contained. Is replaced with fluorine (F), and the superconducting current flows there. Hereinafter referred to a layer of the oxide and Cu-O ₂ surface.

Further, the metal atomic layer represented by the formula (1) is interposed between the above-mentioned Cu-O ₂ planes to neutralize the −2 valent charge on the Cu—O ₂ planes, and thus the entire crystal. It is a layer that functions to keep the structure stable. Hereinafter, this layer is referred to as a mediating layer. First, in the superconductor of the present invention, β is originally 1 when (Ca _1- γMγ) does not have a Ca (or Sr) site defect in the mediating layer represented by the formula (1). Should be.

However, when this mediating layer is formed in a state where β is a value larger than 1, defects may occur in Cu sites on the Cu—O ₂ planes located above and below this layer. When the amount of Cu deficiency becomes too large, the superconducting current does not flow on the Cu—O ₂ surface, and the superconducting property is lost. Therefore β
Has an upper limit value, and that value is 1.1.

On the other hand, when this mediating layer is formed in a state that β is smaller than 1, a slight defect may be included in the Ca (or Sr) site in the mediating layer. And such (C
The deficiency of the (a _1- αSrα) site means that it is equivalent to the state where holes are injected into the superconductor, which is not preferable for some electron superconductors. Therefore, there is a lower limit for β, which is 0.9.
And

After all, in the composition of the superconductor (Cu _1- γ
A value β indicating the ratio of (Ca _1- αSrα) to Mγ)
Is set within the range of 0.9 ≦ β ≦ 1.1. On the other hand, a value representing the abundance ratio of Ca and Sr in (Ca _1- αSrα) of the mediating layer: α can produce a superconductor even when only Ca (α = 0), and conversely Sr. Even if only (α = 1), since the superconductor can be manufactured, the lower limit value of α is 0 and the upper limit value is 1.

After all, Ca in the mediating layer
The ratio of α to Sr: α is set within the range of 0 ≦ α ≦ 1.0. However, when a SrTiO ₃ single crystal is used as a substrate when manufacturing a superconductor, the a-axis length of the single crystal is
Since it is as long as 0.390 nm, when the abundance ratio of Ca is high,
It may not be possible to form a superconductor due to the mismatch with the substrate. Therefore, it is preferable to promote crystal growth by setting α within the range of 0.65 ≦ α ≦ 0.95 so that the abundance ratio of Sr increases.

[0014] In the superconductor of the present invention, injection of charge carriers into the Cu-O ₂ surface (electrons), each part of the Cu sites and O sites in the Cu-O ₂ side, an element of different valences It is realized by replacing. First,
At the Cu site, electrons are injected by substituting a part of +2 valent Cu with a +3 valent metal M. Specifically, it is substituted with Ga or / and Al.

In this case, when the substitution amount γ of Ga and / or Al for Cu becomes too large, the ionic radius of Cu ²⁺ is 57 pm, whereas the ionic radii of Ga ³⁺ and Al ³⁺ are 47 pm, respectively. , 39 pm, and because the charge balance is lost in the entire crystal structure, the superconductor cannot hold the structure and is not formed as a single phase.

Therefore, γ has an upper limit value, and it is necessary to limit the value to 0.20. Further, since the charge carriers can be injected into the Cu—O ₂ plane only by the substitution at the O site, the lower limit value of γ is 0.
After all, the substitution amount γ of Ga or / and Al at the Cu site is set within the range of 0 ≦ γ ≦ 0.20.

On the other hand, at the O site, electrons are injected by substituting part of the -2 valent oxygen with -1 valent fluorine. Although the ionic radii of oxygen and fluorine are similar values, even in this case, as in the case of the Cu site, if the substitution amount δ of fluorine becomes too large, the charge balance in the entire crystal structure is lost. As a result, the entire crystal structure cannot be retained.

For this reason, there is an upper limit value for the fluorine substitution amount δ, and it is necessary to limit the value to 0.25. Further, since the charge carriers can be injected into the Cu—O ₂ plane only by the substitution at the Cu site, the lower limit value of δ is 0. After all, the fluorine substitution amount δ at the O site is set within the range of 0 ≦ δ ≦ 0.25.

In the superconductor of the present invention, γ and δ are independently set as numbers satisfying the above range, but here, γ and δ never become 0 at the same time.
The fact that γ and δ are simultaneously set to 0 means that neither Ga or / and Al at the Cu site nor fluorine at the O site is substituted, which means that the Cu—O ₂ plane This is because it means that charge carriers are not injected into.

By the way, oxygen in the superconductor of the present invention is the only anion, and the charge carrier is the electron. Therefore, in order to increase the carrier concentration in the Cu-O ₂ surface it will be preferable to realize the injection state of electrons creating oxygen vacancies in the Cu-O ₂ surface. However, if the oxygen deficiency becomes too large, the crystal structure of the manufactured superconductor becomes unstable and the structure cannot be maintained. Therefore, the oxygen deficiency amount naturally has an upper limit value. That is, the upper limit value of ε representing the oxygen deficiency amount is set to 0.04.

Since, as described above, charge carriers can be injected into the Cu—O ₂ plane without oxygen deficiency, the lower limit of ε is 0. After all, the value ε representing the amount of oxygen deficiency is set within the range of 0 ≦ ε ≦ 0.04. Considering the optimization of carrier concentration, 0 ≦ ε ≦ 0.02
Is preferred.

The superconductor of the present invention can be used in various shapes such as tape, wire, fiber and sheet. Further, it can be used by forming it on a reinforcing material made of carbon fiber, ceramics such as alumina and zirconia, or metal such as gold and silver. Further, these ceramics or gold or silver can be coated and used. Furthermore, it can be used as a superconducting wire having a multi-core wire structure using copper or the like as a matrix. In addition, Si,
MgO, LaGaO ₃ , LaAlO ₃ , NdGaO ₃ ,
NdAlO ₃ , LaSrGaO ₄ , Y ₂ O ₃ , SrTi
It can be formed as a thin film on a substrate of O ₃ , Al ₂ O ₃ , yttrium partially stabilized zirconia or the like and used as various elements or as wiring of LSI.

When forming the superconductor of the present invention on a substrate
In advance, the crystal system is similar to the superconductor on the substrate,
In addition, Bi that is rich in surface smoothness when formed as a thin film₂
Sr ₂CuO₆And Bi₂Sr₂Ca₁Cu₂O₈Such
1 to 20 unit lattice number of so-called Bi-based superconductor
Preferably. However, in this case, the
The substrate temperature when forming the superconductor is the Bi-based superconductor.
Substrate in which 1 to 20 unit lattice numbers of 1 are not formed on the substrate surface
10 ° C. to 200 ° C. higher than the case of using. Well
After forming the superconductor of the present invention,
It is preferable to coat them with so-called Bi-based superconductors.
Yes.

The surface condition of the substrate is important when the superconductor of the present invention is formed thereon. Specifically, it is preferable to take a treatment to burn off the surface deposit in a high vacuum in advance so that no impurities are attached and epitaxial growth is possible. Especially when SrTiO ₃ single crystal is used as the substrate, the temperature is about 1000 ° C.
Since the surface is formed with a layer containing a large amount of Ti by the heat treatment up to, when forming a superconductor on this, first stack Sr on the first layer, then Cu, and then the purpose. It is preferable to continuously form the crystal structure of the superconductor.

Further, as a method for heating the substrate in the case of forming the superconductor of the present invention on these substrates, heating by directly energizing the substrate is the best from the viewpoint of uniformity of heat generation and stability. For example, it is preferable to heat the substrate so that the substrate has appropriate conductivity by means such as doping SrTiO ₃ with Nb. The superconductor of the present invention is
Since it cannot be produced by the usual solid-phase reaction method, the formula
It is preferable to apply the stacking method that can control stacking of the atomic layer of metal shown in (1) and the oxide layer shown in formula (2) by atomic order.

As this stacking method, for example, a laser ablation method, a molecular beam epitaxy method, an electron beam vapor deposition method, or a physical vapor deposition method such as various sputtering methods can be applied. Of these methods, in particular, Laser ablation methods are preferred. For example, when manufacturing the superconductor of the present invention by the laser ablation method, the operation proceeds as follows.

First, a copper oxide target is manufactured. That is, for example, CuO and Ga ₂ O ₃ (or Al ₂ O ₃ ) powders are mixed so that the molar ratio of Cu and Ga (or Al) is 1-γ: γ, and pellets are mixed with the mixed powder. Mold. At this time, when it is desired to replace O with F, a predetermined amount of CuF ₂ powder may be mixed instead of CuO in accordance with the target replacement amount δ.

Then, the above pellets are added to 800-1000.
The target 1 is fired and sintered at a temperature of ℃ for 1 to 12 hours.
And On the other hand, pelletized Sr metal target (target 2) and Ca metal target (target 3)
To prepare. Next, the targets 1, 2 and 3 are separately set in the rotary holder of the vacuum chamber, and the substrate is set at a position facing these targets and separated by 5 to 150 mm. After the partial pressure of oxidizing gas such as NO ₂ or ozone in the chamber is set to 1 × 10 ^-2 to 1 × 10 ^-4 Pa, the substrate is heated to 400 to 600 ° C., preferably 450 to 550 ° C. To do. Then, rotate the holder to target 1, target 2, target 3,
Excimer lasers using ArF, KrF, and XeCl are sequentially irradiated, and constituent materials of each target are alternately deposited on the substrate.

At this time, by irradiating the substrate or the periphery thereof with a laser, the crystallinity of the obtained thin film can be enhanced or the oxidizing power of the oxidizing gas can be strengthened. In addition,
The energy density per laser pulse at the irradiation position on the target needs to be larger than the size at which ablation occurs, but is preferably 1 kJ / cm ² or less. If it is larger than this, the shape of the thin film may be deteriorated.

The pulse frequency of the excimer laser used for irradiation varies depending on the type of target used and the type of desired ablation excitation species, but if this frequency is too high, the number of atoms ablated and flying at the substrate surface will increase. The rearrangement may be incomplete and the crystallinity may be deteriorated. Therefore, the pulse frequency of the excimer laser used is preferably about 1 to 80 Hz.

If the distance between the target and the substrate is less than 5 mm, the substrate becomes an obstacle to laser irradiation,
Since the irradiation angle of the excimer laser with respect to the target must be made extremely small, the ablation of the target is less likely to occur. Also, 150 mm
If it is larger than the above range, the deposition rate on the substrate is remarkably slowed down, which is not practical.

In order to create an oxidizing atmosphere in the chamber, oxygen or N ₂ O may be used in addition to NO ₂ and ozone, or ozone or active oxygen may be generated by irradiating the oxygen atmosphere with ultraviolet rays or the like. You may. When the partial pressure of the oxidizing atmosphere in the vacuum chamber is lower than 1 × 10 ⁻⁴ Pa, Cu ₂ O is generated as a stable phase in the obtained crystal structure, and a superconductor may not be obtained. Also, 1 × 10
^If it is higher than ^-2 Pa, impurities may be easily mixed in the formed copper composite oxide, or the morphology of the resulting thin film may be significantly reduced.

Further, if the substrate temperature is lower than 400 ° C., crystallization of the target material deposited on the substrate becomes difficult to occur, while if it is higher than 600 ° C., a superconductor may not be obtained. When ablating each target, the thickness of the metal atomic layer or oxide layer formed is directly monitored by a film thickness meter, or the correlation between the working time and the thickness when a standard sample is ablated Was obtained in advance, by referring to the data, the actual working time was measured and the thickness was monitored from that value, and when the thickness reached the desired thickness,
Switch the irradiation target of the excimer laser to another target.

By such a laser ablation method, a mediating layer made of an atomic layer of Ca (or Sr) and Cu—O ₂ planes are alternately laminated infinitely on the substrate, Atomic layer and the above Cu-O ₂
A thin film is formed with the minimum unit of the two layers of the surface. Therefore, for the thickness control of each atomic layer, the reflection high-energy electron diffraction method (RHEED) is applied, the intensity of the diffraction grating point is monitored on the image obtained at that time, and the atomic pattern is monitored from the vibration pattern. It is preferable to adopt a method of estimating the thickness of the layer and switching the irradiation of the excimer laser to another target when the thickness reaches a desired thickness.

However, in the case of this method, as the thickness of the formed film becomes thicker, the intensity of the diffraction grating point on the image becomes weaker, and as a practical problem, it becomes impossible to control the film thickness. After that, the working time required to form one atomic layer was measured by the RHEED image up to about the first 10 atomic layers, and after that, each layer was formed so that the desired number of atomic layers was formed. The method of continuing the membrane is preferred.

After stacking the atomic layers, 1 second to
It is preferable to set an interval of about 15 minutes because the crystallinity of each atomic layer becomes more reliable. The interval may be changed at any time or sequentially, such that the interval is initially long and is shortened as the film thickness increases. In this way, a thin film is formed on the substrate, laser irradiation is stopped when the thickness reaches a desired value, and the substrate is cooled to about 200 to 450 ° C. at a temperature lowering rate of about 5 to 20 ° C./min. At this time, a slight oxygen deficiency can be created by lowering the partial pressure of the oxidizing gas in the chamber or by holding at a certain temperature in the temperature range of 200 to 400 ° C. for 1 to 60 minutes and then rapidly cooling. Similarly, in order to create an oxygen deficiency, after forming the film, the film is heated to 200 to 400 ° C.
It is also possible to apply a method of quenching After N ₂ annealing in 0.1 atm over 1 to 300 minutes at a temperature.

When the F substitution at the O site is insufficient, the thin film after film formation is placed in a tube made of a corrosion-resistant material such as Monel metal, and an F ₂ gas of 0.1 to 1 atm is used. It can be enclosed together with and can be treated under the same conditions as the above N ₂ annealing. The above description is for the case of using three targets, but in the present invention, the target 1 for forming the Cu—O ₂ surface is used.
May be divided into three targets of CuO, M ₂ O ₃ (M: Ga or / and Al), and CuF ₂ , respectively.

On the contrary, the composition of the desired superconductor
This target is manufactured by manufacturing one target with the composition
It is also possible to carry out a film forming operation using a tablet. For example,
(Ca _0.8Sr_0.2) (Cu_0.9Ga_0.1) O₂With the composition of
When manufacturing a superconductor that
Then CaCO₃, SrCO₃, CuO, Ga₂O₃Each of
Select powders, and use these powders for Ga, Sr, Cu, Ga
To obtain a molar ratio of 8: 2: 9: 0.5,
The mixed powder may be sintered to be a target.

When the superconductor of the present invention is manufactured by the stacking method, the concentration of charge carriers in the crystal structure may be partially changed. That is, a so-called superlattice structure can be obtained by periodically modulating the injection concentration of charge carriers.

[0040]

【Example】

Example 1 CuO powder and Ga ₂ O ₃ powder were mixed so that the molar ratio of Cu and Ga was 8: 2, which was then molded into pellets, and the pellets were baked at a temperature of 1000 ° C. for 10 hours. The target was cooled after cooling. On the other hand, Ca and Sr
Each of the metal pellets was prepared, and Ca was used as a target 2 and Sr was used as a target 3.

Next, these targets are separately set on the rotary holder of the vacuum chamber, and the surfaces are (100) faces facing these targets and 100 mm away from each target. A SrTiO ₃ substrate was placed, the partial pressure of the oxidizing atmosphere (NO ₂ ) in the vacuum chamber was adjusted to 1 × 10 ⁻³ Pa, the substrate was heated to 600 ° C., and held for about 15 minutes. Then, the substrate was cooled to 480 ° C. and kept at that temperature. Then,
Observe the reflection high-energy electron diffraction image of the substrate surface and confirm that the crystallinity and smoothness of the substrate surface are sufficient.
The intensity of the diffraction spot was monitored. Hereinafter, in the film forming process, it was confirmed that this monitor was continued and that each atomic layer was laminated.

An ArF excimer laser with a wavelength of 193 nm was used as the laser. The energy density of the laser pulse is about 300 when measured with a calorimeter.
It was mJ / cm ² . First, the target 2 is irradiated with a laser to perform ablation, and then the rotary holder is rotated to ablate the target 3.
Ca and Sr were supplied onto the substrate so that Sr = 8: 2.

At this time, the diffraction point intensity of the RHEED image was monitored, the supply of Ca and Sr was stopped when the vibration became 1/2 amplitude, and a layer of Ca _0.8 Sr _0.2 was formed by ablation of the targets 2 and 3. It was confirmed that the film was formed with a thickness of one atomic layer. Then, laser ablation of the target 1 is performed, and the supply is stopped when the diffraction spot intensity of the RHEED image also becomes 1/2 amplitude, so that the target 1 causes (Cu _0.8 Ga _0.2 ) O ₂₋
It was confirmed that the layer of ε was formed with a thickness of one atomic layer.

After that, the laser is changed to target 2 → target 3 → target 1 → target 2 → target 3
→ Target 1 was irradiated to each target in a cyclic cycle to perform film formation operation. After the film forming operation was completed, the whole was annealed in a N ₂ atmosphere at 1 atm and 300 ° C. for 30 minutes and then rapidly cooled.

When X-ray diffraction analysis was performed on the thin film formed on the substrate, it was confirmed that this thin film was a single phase in which atomic layers were alternately laminated infinitely. With respect to this thin film, the composition ratio of each element was examined by EPMA (wavelength dispersive spectroscopy). The composition is (Ca _0.8 Sr _0.2 ).
It was confirmed to be (Cu _0.8 Ga _0.2 ) O _1.98 .

When the magnetic susceptibility was examined by SQUID, it showed diamagnetism at 45K, and this thin film had Tc: 45K.
It was confirmed to be a superconductor. Example 2 The same operation procedure as in Example 1 except that a CuF ₂ powder sintered body was used as the target 1 and Ca and Sr were supplied to the substrate so that the molar ratio was 3: 7. The film formation operation was carried out.

After completion of the film forming operation, the whole is kept at 1 atm for 30 atmospheres.
It was annealed in a N ₂ atmosphere at 0 ° C. for 30 minutes and then rapidly cooled. When X-ray diffraction analysis was performed on the thin film formed on the substrate, it was confirmed that this film formation was a single phase in which atomic layers were alternately laminated infinitely. With respect to this thin film, the composition ratio of each element was examined by EPMA (wavelength dispersive spectroscopy). The composition is (Ca _0.3 Sr _0.7 ) Cu
It was confirmed that it was (O _0.9 F _0.1 ) _1.98 .

When the magnetic susceptibility was examined by SQUID, it was confirmed that the thin film showed diamagnetism at 40K, and that this thin film was a superconductor having Tc: 40K. Example 3 CuO powder, Al ₂ O ₃ powder, and CuF ₂ powder were
After mixing so as to have a molar ratio of 4.5: 2: 4.5, pellets were molded, and the pellets were fired at 950 ° C. for 10 hours and then cooled to obtain a target 1.

Then, a film forming operation was carried out by the same operation procedure as in Example 1 except that Ca and Sr were supplied onto the substrate so that the molar ratio was 7: 3. After the film forming operation is completed,
30 at a pressure of 300 ℃ N ₂ atmosphere 1 atmosphere
It was annealed for a minute and then rapidly cooled. The composition of the thin film found by EPMA is (Ca _0.7 Sr _0.3 ) (Cu _0.9 Al _0.1 ).
It was (O _0.95 F _0.05 ) _1.97 . The Tc measured by magnetic susceptibility was 38K.

[0050]

As is apparent from the above description, the superconductor of the present invention has, in its crystal structure, an atomic layer scale Cu—O ₂ plane through which a superconducting current flows and an atomic layer scale mediator that neutralizes charges. It has an infinite layer structure in which the coating layers are alternately laminated, and is manufactured by a so-called stacking method such as a laser application method capable of controlling an atomic unit. As shown, the carrier concentration can be optimized and T
It is a superconductor with a high c. In addition, since a so-called stacking method is adopted in manufacturing, a superconductor having a target structure can be easily manufactured based on design criteria.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C23C 14/08 ZAA L 9271-4K C30B 25/06 ZAA H01B 12/06 ZAA 7244-5G 13/00 565 D 7244 -5G H01L 39/02 ZAA B 9276-4M 39/24 ZAA B 9276-4M

Claims (3)

[Claims] 1. The following formula: (Ca _1- αSrα) β (Cu _1- γMγ) (O _1- δFδ)
_2- ε (In the formula, M represents Ga or / and Al, and α, β,
γ, δ and ε are 0 ≦ α ≦ 1 and 0.9 ≦ β ≦ 1 respectively.
1, 0 ≤ γ ≤ 0.20, 0 ≤ δ ≤ 0.25, 0 ≤ ε ≤ 0.04
Represents the number that satisfies. However, γ and δ do not become 0 at the same time). 2. A superconductor comprising a base material and a thin film of the superconductor according to claim 1 formed on the base material. 3. Using the stacking method, the following formula: (Ca _1- αSrα) β (where α and β are 0 ≦ α ≦ 1 and 0.9 ≦ β ≦, respectively)
A metal atomic layer represented by the formula ( ₁ ) is formed on the metal atomic layer and a stacking method is used to form the following formula: (Cu _1- γMγ) (O _1- δFδ) _{2 -} epsilon (where, M represents Ga or / and Al, γ, δ,
ε is 0 ≦ γ ≦ 0.20, 0 ≦ δ ≦ 0.25,0, respectively.
Represents a number that satisfies ≦ ε ≦ 0.04. However, γ and δ do not become 0 at the same time). A method for producing a superconductor characterized by repeating the operation of forming a copper oxide layer.