JP3473201B2 - Superconducting element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting element of superconducting application technology, and more particularly to a superconducting element using an oxide superconductor.

[0002]

2. Description of the Related Art In recent years, some oxide superconductors discovered have a superconducting critical temperature exceeding liquid nitrogen temperature, which has greatly expanded the field of application of superconductivity.

As one of the practical applications of the superconducting element, a crack type element in which an oxide superconductor is divided into two and slightly contacted again, and the oxide superconductor is made into a thin film to form a small constriction. A bridge type device with a mark, a flat type thin film device such as a bicrystal type device in which a superconducting thin film is formed on a substrate in which two types of bases are connected, and an insulator or semiconductor on an oxide superconducting thin film. Alternatively, a laminated junction type superconducting device in which a metal or the like is laminated and an oxide superconductor is laminated thereon has been conventionally manufactured.

Among the elements that have been prototyped in the past, crack type elements and flat type thin film elements are formed by utilizing the grain boundary portions produced during thin film formation, so that important junction parameters such as critical current density are reproduced. It was difficult to get sex. In addition, the laminated junction type superconducting device reflects the two-dimensional growth property of the oxide superconductor in accordance with the Strauski-Krastanov-like growth mode, so that a stable laminated interface is easily formed, but the coherence length in the laminating direction is Since it is short, it is necessary to form very thin insulator layers, semiconductor layers, and metal layers in order to form superconducting junctions, so eliminating defects such as pinholes is one of the important issues. there were.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a superconducting device capable of obtaining a stable and high quality device with good reproducibility in order to solve the problems of the prior art.

[0006]

In order to achieve the above object, a superconducting element of the present invention is a superconducting normal-conducting thin film formed on a substrate inclined by a predetermined angle, and an oxidation film formed thereon. It is characterized in that it is operated by applying a current between a normal conductive thin film having conductivity and a metal electrode through an oxide superconducting thin film. Alternatively, it is composed of a conductive substrate having a surface inclined by a predetermined angle, an oxide superconducting thin film formed on the surface, and a metal electrode formed on the substrate, and the conductive film is formed through the oxide superconducting thin film. It is characterized in that an electric current is applied between the substrate having the property and the metal electrode to operate. Alternatively, an oxide superconducting thin film formed on a substrate having a surface inclined by a predetermined angle, and at least two or more metal electrodes formed so as to include at least one or more steps of the substrate therebetween. It is characterized in that it is operated by applying a current in the tilt direction of the substrate.

In the present invention, the angle of the tilted substrate is
It is preferably 0.1 to 6 degrees.

[0008]

According to the present invention, by using a substrate tilted at a predetermined angle, it is possible to control nucleation during thin film formation and realize a smooth thin film surface, so that a laminated junction device without pinholes is manufactured. be able to.

The oxide superconducting thin film used is Bi ₂ Sr ₂
According to the preferred constitution of the present invention, which is Ca _n-1 Cu _n O _y (n = 2,3), the strong two-dimensional growth property of these substances according to the Strauski-Krastanov-like growth mode is reflected. As a result, a large particle size and a smooth film surface can be realized over a wide range.

Further, according to the preferable constitution of the present invention in which the angle of the inclined substrate is 0.1 to 6 degrees, nucleation during thin film production can be easily controlled, and a smooth film surface can be realized over a wide range.

[0011]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 First, a method of manufacturing this superconducting device will be described. First, an SrTiO ₃ (100) substrate tilted at a predetermined angle was used as a substrate, and an oxide superconducting thin film and a normal conducting thin film were produced by the RF magnetron sputtering method. The angle of the tilted substrate used was 0.1 degrees (±
0.1 degree), 0.5 degree (± 0.2 degree), 2 degree (± 0.5 degree), 4 degree (± 0.5 degree)
Angle) and 6 degrees (± 0.5 degrees), the inclination is with respect to the [110] direction of the substrate. FIG. 1 is a schematic view of a tilted substrate surface. There is a terrace structure on the surface of the substrate. 01 is the angle of inclination
02 indicates the terrace structure. The root mean square roughness of these substrates was about 0.24 nm on the surface of the terrace portion due to the inclination. The oxide superconductor used was Bi ₂ Sr ₂ CaCu ₂ O _y and the normal conductor was Bi ₂ Sr ₂ CuO _x . FIG. 2 is a schematic view of the inside of the RF magnetron sputtering apparatus used in the first embodiment. In FIG. 2, 11 is a Bi ₂ Sr ₂ CaCu ₂ O _y target, 12 is a Bi ₂ Sr ₂ CuO _x target, 13 is a substrate, and 14 is a substrate holder in which a heater is incorporated. The SrTiO ₃ (100) substrate 13 tilted at a predetermined angle is fixed to the substrate holder 14 with silver paste, rotated, and installed so as to face each target. By controlling the rotation of the substrate holder 14 with a motor,
The substrate 13 can be stopped on 11 and 12 targets. Using this mechanism, the oxide superconductor Bi ₂ Sr ₂ CaCu ₂ O
_y , the normal conductor Bi ₂ Sr ₂ CuO _x , and Bi ₂ Sr ₂ CaCu ₂ O _y
It is possible to fabricate a structure in which The atmosphere for producing these thin films is an argon / oxygen (1: 1) mixed atmosphere of 40 Pa.
Substrate temperature was 700 ° C., and input power to each of targets 11 and 12 was 50 W. After forming the thin film, it was cooled in an oxygen atmosphere. The RHEED pattern of the thin film
A sharp streak was observed in each of the [-1-10] directions,
In the [1-10] direction, streaks tilted by a predetermined angle reflecting the tilt of the substrate were observed.

The superconducting transition temperature in the resistance measurement of the prepared Bi ₂ Sr ₂ CaCu ₂ O _y thin film was 85 K, and the superconducting transition occurred at 72 K.
The resistance was zero. In addition, the resistance measurement using only the Bi ₂ Sr ₂ CuO _x thin film did not show superconductivity but showed a semiconductor-like behavior.

Atomic force microscopes after depositing a lower superconducting thin film on each tilted substrate of the first embodiment, after depositing a normal conducting thin film thereon, and after depositing an upper superconducting thin film ( Observation of the maximum roughness and average grain size at 1 μm × 1 μm on the surface of the thin film by AFM) shows that the variation in grain size is large when using the just (100) substrate without inclination, and the superconducting thin film on top The maximum roughness representing the surface flatness of was about 10 nm,
It was found that the use of the tilted substrate improves the surface flatness, which is important for manufacturing a laminated junction device. It was also found that the surface roughness has a minimum value between 0.5 and 4 degrees. This is probably because nucleation occurs during thin film growth from the end of the terrace portion on the substrate surface. In addition, Bi ₂ Sr ₂
The Ca _n-1 Cu _n O _y (n = 1,2,3) thin film has a diffusion coefficient in the ab axis direction which is extremely larger than that in the c axis direction, so that a thin film having a large grain size can be easily grown. It is suitable for laminated junction devices having a layered structure.

The laminated junction element was manufactured by photolithography using a negative resist and ion milling. The junction size is 10 μm × 10 μm. The shapes of these elements are shown in FIG. 31 is a Bi ₂ Sr ₂ CaCu ₂ O _y thin film, 32
Indicates a Bi ₂ Sr ₂ CuO _x thin film. FIG. 4 shows a typical current-voltage characteristic of the present invention. This characteristic can be accurately matched by the RSJ model. By irradiating this junction with microwaves, a clear Shapiro step was observed, and by irradiating microwaves with higher power, the critical current could be suppressed to zero, so that a good superconducting junction was formed. You can see that The Shapiro step was observed in all of the laminated junctions formed on each inclined substrate, but when the variation of the critical current value, which is an important parameter for the junction characteristics, was examined, the inclination angle was the smallest from 2 degrees to 4 degrees. . That is, according to this example, it can be said that a laminated superconducting junction having good reproducibility and good quality can be manufactured.

Example 2 Similar to Example 1, SrTiO ₃ (1) tilted at a predetermined angle was used.
(00) Using the substrate as a substrate, an oxide superconducting thin film and a normal conducting thin film were produced by the RF magnetron sputtering method. The angle of the tilted substrate used is 1.7 degrees (± 0.5 degrees)
Then, the inclination is attached to the [110] direction of the substrate.
The oxide superconductor used is Bi ₂ Sr ₂ Ca ₂ Cu.
₃ O _y , the normal conductor is Bi ₂ Sr ₂ NdCu ₂ O _x . FIG. 5 is a schematic view of the inside of the RF magnetron sputtering apparatus used in the second embodiment. In FIG. 5, 51 is Bi 2
O 3 target, 52 is SrCuO _x target, 53
Is a CaCuO _z target, 54 is a Nd ₂ O ₃ target, 55 is a shutter, and 13 is a substrate. By controlling the rotation of the shutter 55 with a motor, the substrate 13
, 51, 52, 53 and 54 targets can be selected. Using this mechanism, the oxide superconductor Bi ₂
Sr ₂ Ca ₂ Cu ₃ O _y , on top of which the normal conductor Bi ₂ Sr
₂ NdCu ₂ O _x , further Bi ₂ Sr ₂ Ca ₂ Cu ₃ O
A structure in which _y is stacked can be manufactured. The atmosphere for producing these thin films is a mixed atmosphere of argon / oxygen (5: 1) gas of 3.5 Pa, and the substrate temperature is 640 ° C.
The input powers to the targets 1, 52, 53 and 54 were 10 W, 14 W, 85 W and 50 W, respectively. After forming the thin film, it was cooled in an oxygen atmosphere. In the RHEED pattern of the produced thin film, a sharp streak was observed in each of the [-1-10] directions, and a streak inclined by a predetermined angle reflecting the tilt of the substrate was observed in the [1-10] direction.

The superconducting transition temperature of the prepared Bi ₂ Sr ₂ CaCu ₂ O _y thin film in the resistance measurement was 110 K, and the superconducting transition occurred.
The resistance was zero at K. In addition, Bi ₂ Sr ₂ NdCu ₂ O _x
In resistance measurement with only thin film, it does not show superconductivity,
It showed a semiconductor-like behavior.

Observation of the maximum roughness and average grain size at 1 μm × 1 μm on the surface of the thin film by AFM after film formation on the inclined substrate of this Example 2 revealed that a just (100) substrate without inclination was used. The maximum roughness that shows the surface flatness with a large variation in grain size was about 22 nm, but it was found that the surface flatness, which is important for the fabrication of laminated junction devices, is improved by using a tilted substrate. . Bi ₂ Sr ₂ Ca _n-1 Cu _n O _y (n = 1,2,3) thin film has an extremely large diffusion coefficient in the ab-axis direction compared to the c-axis direction, so it is easy to grow a thin film with a large grain size. It is suitable for a laminated junction device having a three-layer structure of the present invention.

The laminated junction element was manufactured by photolithography using a negative resist and ion milling. The junction size is 5 μm × 10 μm. Similar to Fig. 4, typical current-voltage characteristics can be accurately matched by the RSJ model. By irradiating this junction with microwaves, a clear Shapiro step was observed, and by irradiating microwaves with higher power, the critical current could be suppressed to zero, so that a good superconducting junction was formed. You can see that According to the present example, it can be said that a laminated superconducting junction with good reproducibility can be manufactured. Further, in the second embodiment, the details of the tilted substrate at an angle of 1.7 degrees are shown, but it was found that a similarly good superconducting element can be prepared at 0.1 to 6 degrees.

Example 3 Using the SrTiO ₃ (100) substrate tilted at a predetermined angle as a substrate, an oxide superconducting thin film and a normal conducting thin film were prepared by the RF magnetron sputtering method used in Example 1. The tilted substrate used has an angle of 0.1 degree, and the tilt is with respect to the [110] direction of the substrate. The oxide superconductor used is Bi ₂ Sr ₂ CaCu.
₂ O _y , the normal conductor is Sr ₂ CuO ₄ . Sr ₂ RuO ₄ can have a superconducting transition temperature below about 1K in K ₂ NiF ₄ type having a perovskite structure Bi ₂ Sr ₂ CaCu ₂ O _y and lattice matching is good conductive material, the substrate SrTiO ₃ Has excellent wettability. In Example 3, 11 used in FIG. 2 was a Bi ₂ Sr ₂ CaCu ₂ O _y target, and 12 was Sr ₂
CuO ₄ target, 13 is a substrate, and 14 is a substrate holder with a heater incorporated therein. The atmosphere for forming these thin films was a mixed atmosphere of argon / oxygen (9: 1) gas of 5 Pa, the substrate temperature was 700 ° C., and the input power to each of targets 11 and 12 was 40 W. After the thin film was formed, it was cooled in the same atmosphere as when the film was formed. Using this mechanism, oxide conductor Sr2RuO4, oxide superconductor Bi ₂ Sr ₂ Ca _n-1 Cu _n O _y (n = 1,2,
3) A thin film can be produced. In the RHEED patterns of the thin films prepared, sharp streaks were observed in all [-1-10] directions, and streaks tilted at a certain angle reflecting the tilt of the substrate were observed in the [1-10] direction.

The superconducting transition temperature in the resistance measurement of the prepared Bi ₂ Sr ₂ CaCu ₂ O _y thin film on Sr ₂ RuO ₄ was such that the superconducting transition occurred at 85 K and the resistance became zero at 65 K. 1 μm × 1 μm on the surface of the thin film formed by the atomic force microscope (AFM) on the surface of the superconducting thin film formed on each inclined substrate of this Example 3.
I checked the maximum roughness at
When the (100) substrate was used, the variation in grain size was large, and the maximum roughness showing the surface flatness was about 4 nm. 1 μm x 1 μm
From the relationship between the maximum roughness and the substrate tilt angle, it was found that the use of a tilted substrate of 0.5 to 4 degrees improves the surface flatness, which is important for the fabrication of laminated junction devices. This is probably because nucleation occurs during thin film growth from the end of the terrace portion on the substrate surface. The laminated junction element was manufactured by photolithography using a negative resist and ion milling. FIG. 6 shows the shape of the element in the third embodiment. The junction size was 2 μm × 4 μm and was formed on the flat terrace portion of the inclined substrate. 13 is the substrate, 61 is Bi ₂ S
r ₂ CaCu ₂ O _y thin film, 62 Sr ₂ RuO ₄ thin film, and 63 gold electrode. The current-voltage characteristics between Sr ₂ RuO ₄ and the gold electrode through the c-axis direction of Bi ₂ Sr ₂ CaCu ₂ O _y were observed, and superconducting device characteristics were observed. Furthermore, a voltage jump was observed near zero voltage. R. Kleiner et al., Physical Review B (vol.49
p.1327-1341, 1994) reported that voltage jump was observed in the current-voltage characteristics in the c-axis direction using Bi ₂ Sr ₂ CaCu ₂ O _y single crystal. From this, Bi ₂ Sr ₂ CaCu ₂ O _y
This is a high-quality superconducting junction itself, and in the third embodiment, a graded Bi ₂ Sr ₂ CaCu ₂ O _y thin film is manufactured by using an inclined substrate and further using Sr ₂ RuO ₄ having good wettability for the substrate. And realize B
It can be seen that a high-quality superconducting junction of i ₂ Sr ₂ CaCu ₂ O _y can be provided. That is, it can be said that according to the third embodiment, a superconducting junction having good reproducibility and high quality can be manufactured.

Further, in the present embodiment, details of the case of using Sr ₂ RuO ₄ are shown, but (Sr, Ca) RuO ₃ or doped SrTiO ₄ is used.
_It was found that a good superconducting device can be produced also with Nb: SrTiO ₃ (Nb: 0.05% (0.05% Nb doped)) which is 3.

In the third embodiment, the angle of the inclined substrate is 0.1
However, it was found that a good superconducting device could be produced at 0.1 to 6 degrees.

Example 4 An oxide normal conductive thin film and an oxide superconducting thin film were prepared by a reactive vapor deposition method using an MBE (Molecular Beam Epitaxy) device using a SrTiO ₃ (100) substrate tilted at a predetermined angle as a substrate. . The angle of the tilted substrate used is 1.7 degrees, and the tilt is with respect to the [110] direction of the substrate. FIG. 7 shows the fourth embodiment.
3 is a schematic view of the inside of the MBE device used in FIG. 71 in FIG.
Is a Bi cell, 72 is an Sr cell, 73 is a Ca cell, 74 is a Cu cell, 75 is a radical gun, 76 is a partition plate, 77 is a SiC heater, 78 is a substrate holder, 79 is a film thickness monitor, and 13 is a substrate. is there. The SrTiO ₃ (100) substrate 13 tilted at a predetermined angle is the substrate holder 78.
It is fixed to. The vapor deposition of metallic elements is performed using the Knudsen cell (Kc
ell) 71, 72, 73, 74 gave stable evaporation.
As a reaction gas, a radical gun 65 was used to introduce oxygen containing activated radicals into the vacuum chamber. A film thickness monitor 79 with a crystal oscillator for measuring the evaporation amount was installed on each evaporation source to enable accurate evaporation amount control. Using this mechanism, each element is vaporized individually and layer-
Atomic layer controlled oxide superconductor Bi by-layer method
_{A 2} Sr ₂ Ca _n-1 Cu _n O _y (n = 1,2,3) thin film can be prepared. The thin film was prepared in oxygen 3 × 10 −3 Pa. First, Sr ₂ RuO ₄ was deposited on the SrTiO ₃ (100) substrate 613, and then Bi ₂ Sr ₂ C was deposited on it.
A film of aCu ₂ O _y was formed. The substrate temperature was 650 ° C., the K-cell temperatures were 71 at 450 ° C., 72 at 450 ° C., 73 at 420 ° C., 74 at 1100 ° C., and the radical gun 75 at a high frequency output of 250 W. In the RHEED patterns of the thin films prepared, sharp streaks were observed in all [-1-10] directions, and streaks tilted at a certain angle reflecting the tilt of the substrate were observed in the [1-10] direction.

The superconducting transition temperature in the resistance measurement of the produced Bi ₂ Sr ₂ CaCu ₂ O _y thin film was 85 K, and the superconducting transition occurred at 65 K.
The resistance was zero. FIG. 8 shows the shape of the bridge-type element in the fourth embodiment. The bridge size is 20 μm × 3 μm. 13 is the substrate, 81 is Bi ₂ Sr ₂ CaCu ₂ O _y
In the thin film, 82 indicates a gold electrode, and the longitudinal direction of the bridge was set to the (110) direction of SrTiO ₃ as shown in FIG. With this configuration, at least one substrate step is included between the electrodes via the bridge, and the current applied between the electrodes also flows in the c-axis direction of Bi ₂ Sr ₂ CaCu ₂ O _y. . When the current-voltage characteristics of Example 4 were observed, superconducting element characteristics were observed. From this, it is considered that in Example 4, the Bi ₂ Sr ₂ CaCu ₂ O _y thin film junctions observed in series were observed. This means that high quality Bi ₂ Sr ₂ CaCu ₂ O _y thin film fabrication can be realized by using the inclined substrate, and a good superconducting junction of Bi ₂ Sr ₂ CaCu ₂ O _y can be provided. That is, it can be said that according to the fourth embodiment, it is possible to manufacture a high-quality superconducting junction with good reproducibility.

In the fourth embodiment, the angle of the tilted substrate is 1.7.
However, it was found that a good superconducting device could be produced at 0.1 to 6 degrees.

Example 5 An oxide superconducting thin film was produced by the RF magnetron sputtering method used in Example 1 using a SrTiO ₃ (100) substrate tilted at a predetermined angle as a substrate. The angle of the tilted substrate used is 1.7 degrees, and the tilt is with respect to the [110] direction of the substrate. The oxide superconductor used is (Bi _0.9 Pb _0.1 ) ₂ Sr ₂ Ca ₂ Cu ₃ O _y
Is. The atmosphere for producing these thin films was the same as in Example 1. After film formation, annealing was performed at 850 ° C. in air.

The superconducting transition occurred at 110 K at the superconducting transition temperature in resistance measurement, and the resistance became zero at 59 K. The laminated junction element was manufactured by photolithography using a negative resist and ion milling. The element shape is the same as in FIG. When the current-voltage characteristics of Example 5 were observed, superconducting element characteristics were observed. From this, it is considered that in Example 5, the (Bi, Pb) ₂ Sr ₂ CaCu ₂ O _y thin film junctions observed in series were observed. This is due to the use of a tilted substrate
It can be seen that a (Bi, Pb) ₂ Sr ₂ CaCu ₂ O _y thin film can be produced and a high-quality superconducting junction can be provided. That is, it can be said that according to the fifth embodiment, it is possible to manufacture a high-quality superconducting junction with good reproducibility.

In the fifth embodiment, the angle of the inclined substrate is 1.7
However, it was found that a good superconducting device could be produced at 0.1 to 6 degrees.

Further, although the details of the case of using the tilted substrate of SrTiO ₃ (100) are shown in the present embodiment, as shown in (Table 1), as with SrTiO ₃ , Bi ₂ Sr ₂ Ca _{n- 1} Good lattice matching with Cu _n O _y (n = 1,2,3), YAlO ₃ (100), LaAlO ₃ (100), LaGaO
_It has been found that similarly good superconducting devices can be produced with ₃ (001), NdGaO ₃ (001) and MgO (100).

[0031]

[Table 1]

According to the present embodiment described above, the superconducting device of the present invention not only realizes a very smooth film surface as an oxide superconducting thin film, but also reproducibly uses a superconducting device utilizing the same. It can be manufactured well, and can be used as a device integration or a superconducting logic circuit.

In these respects, the superconducting element of this embodiment has great practical effects for computer applications, electronic equipment applications and the like.

[0034]

As described above, according to the superconducting element of the present invention, a superconducting element capable of controlling the critical current density, which is important as a junction parameter, with good reproducibility can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a schematic view of an inclined substrate surface.

FIG. 2 is a schematic view of the inside of the RF magnetron sputtering apparatus used in the first embodiment.

FIG. 3 is an external view of a laminated bonding element according to the first embodiment.

FIG. 4 is a diagram showing a typical current-voltage characteristic of this embodiment.

FIG. 5 is a schematic view of the inside of the RF magnetron sputtering apparatus used in the second embodiment.

FIG. 6 is an external view of a laminated junction element according to the third embodiment.

FIG. 7 is a schematic view of the inside of the MBE device used in the third embodiment.

FIG. 8 is a diagram showing the shape of a bridge-type element in the fourth embodiment.

[Explanation of symbols]

01 Angle of tilted substrate 02 Terrace structure of tilted substrate 11 Bi ₂ Sr ₂ CaCu ₂ O _y target 12 Bi ₂ Sr ₂ CuO _x target 13 substrate 14 Substrate holder 31 with heater built-in 31 Bi ₂ Sr ₂ CaCu ₂ O _y thin film 32 Bi ₂ Sr ₂ CuO _x thin film 33 Gold electrode 34 CaF ₂ film 51 Bi ₂ O ₃ 52 SrCuO _x 53 CaCuO _y 54 Nd ₂ O ₃ 55 Shutter 61 Bi ₂ Sr ₂ CaCu ₂ O _y thin film 62 Sr ₂ RuO ₄ thin film 63 Gold electrode 64 CaF ₂ film 71 Bi cell 72 Sr cell 73 Ca cell 74 Cu cell 75 Radical gun 76 Partition plate 77 SiC heater 78 Substrate holder 79 Film thickness monitor 81 Bi ₂ Sr ₂ CaCu ₂ O _y thin film 82 Gold electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-196762 (JP, A) JP-A-6-260693 (JP, A) JP-A-6-5940 (JP, A) JP-A-4- 332180 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 39/00-39/24

Claims (5)

(57) [Claims] 1. A normal conductive thin film having conductivity formed on a surface of a substrate having an inclination angle of 0.1 to 6 degrees with respect to a crystal axis of the substrate, and an oxidation formed on the normal thin film. Object superconducting thin film, further comprising a metal electrode formed on the oxide superconducting thin film, and applying an electric current between the normal conducting thin film having conductivity and the metal electrode through the oxide superconducting thin film. A superconducting device, wherein the normal conductive thin film is Sr ₂ RuO ₄ or (Sr, Ca) RuO ₃ or Nb: SrTiO ₃ 2. The oxide superconducting thin film is Bi 2 Sr 2 C.
The superconducting element according to claim 1, wherein the superconducting element is an n-1 Cu n O y (n = 1.2.3 ...). 3. The substrate is MgO, SrTiO ₃ or YAlO ₃ , LaAlO ₃ , LaGaO ₃ , NdGa.
The superconducting device according to claim 2, wherein the superconducting device is O ₃ . Against 4. A substrate crystal axis has a tilt angle of the range of 0.1 to 6 degrees, and oxides formed on a substrate and the substrate surface with a conductive superconducting thin film, further It is composed of a metal electrode formed on the oxide superconducting thin film,
A current is applied between the substrate having conductivity through the oxide superconducting thin film and the metal electrode to operate, and the substrate is Nb: Sr made of doped SrTiO _3.
A superconducting device characterized by being TiO ₃ . 5. The oxide superconducting thin film is Bi 2 Sr 2 C.
The superconducting element according to claim 4, wherein the superconducting element is a n-1 Cu n O y (n = 1.2.3 ··).