JP2002220230A - Super conductive material of quantum-defect flux pinning type and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconductive material of a quantum-defect flux pinning type which is a copper oxide super conductor having a spin quantum defect, a superconductive coherence length long in the direction of an axis c, and a small superconductive anisotropy, so as to have a large irreversible magnetic field (Hirr), a high critical electric current density (Jc), and a high superconductivity transition temperature (Tc), and to provide a method of manufacturing the same. SOLUTION: The spins of Cu elements around an Mg ion having no spin are largely polarized by spin interaction to be lined up in one direction. By the polarized magnetic field, superconductive pairs of electrons in the vicinity of the polarization are destroyed and become a non-superconductive phase or a superconductive phase having a low superconductivity transition temperature so that the phase is easily entered by a flux and acts as a flux pinning center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high performance device having a high superconducting critical temperature (Tc), a high critical current density (Jc) and a high irreversible magnetic field (Hirr) by introducing a flux pinning center by spin quantum defects. High-temperature superconducting material,
The present invention relates to a manufacturing method capable of greatly reducing manufacturing costs. This material and technology can be used as a superconducting material technology in various fields of energy, environment, information and communication, transportation, and medicine. The present invention requires a high superconducting critical temperature (Tc), a high critical current density (Jc), a high irreversible magnetic field (Hirr), and a direction perpendicular to the superconducting layer (this direction is the c-axis direction, and a , B axis), a long coherence length (ξ) is required not only in the c-axis direction but also in the a- and b-axis directions, or a superconducting material having extremely excellent superconducting performance and a manufacturing technique thereof are required. Available for all fields.

[0002]

2. Description of the Related Art Conventionally, in a copper oxide superconductor having a high superconducting anisotropy, a coherence length (ξc) in the c-axis direction is 0.3 nm or less in a Y, Bi, Tl, Hg-based superconductor. Due to its short length, the introduction of flux pinning centers due to quantum defects does not work very effectively. For this reason, the introduction of the flux pinning center is for normal defects (lattice defects, dislocations,
It has been achieved by the formation of a micro non-superconducting phase due to voids, grain boundaries, precipitated phases, amorphous phases, etc. Therefore, the superconducting properties of the copper oxide superconductor at 77 K, particularly in a high magnetic field, have not been sufficiently high, and this has been one of the causes of the failure of large-scale practical use at liquid nitrogen temperature.

Further, in the conventional copper oxide superconductor having a layered structure, the charge supply layer is an insulating layer or a non-superconducting layer, and the superconducting coupling in the c-axis direction is small. The superconducting anisotropy γ was as large as about 4 to 300 because the action was small or the thickness of the superconducting layer was small. Here, γ is the anisotropy ratio of the coherence length 、 or the anisotropy ratio of the magnetic field penetration depth λ, and γ = {ab / ξc = λc
/ Λab.

Since the superconducting anisotropy γ is large,
Since the magnetic flux moves in a low magnetic field, electric resistance is easily generated, and Jc,
In particular, the irreversible magnetic field Hirr, which is the upper limit of the magnetic field that maintains Jc under a magnetic field or the electrical resistance of zero (R = 0) (perfect conductivity).
And there have been many problems as wires and bulk materials as practical superconducting materials.

Further, since the anisotropy is large, (Jc) c in the c-axis direction is small, and the coherence length ｃ in the c-axis direction.
c was short, and Jc at the grain boundary in a non-oriented state was extremely low. In addition, the characteristics of the c-axis oriented laminated structure type superconducting element as a superconducting element material, particularly the current density of the Josephson element were insufficient.

On the other hand, in the copper oxide superconductor, the introduction of the flux pinning center due to the quantum defect is not effective for the above-described reason. Therefore, in order to increase the Hirr at 77K to 8T or more, the pinning by heavy ion or neutron irradiation is required. I had to rely on the introduction of the center. In these methods, heavy ions or neutrons are implanted into a superconductor to form an amorphous phase, and this amorphous phase is used as a flux pinning center. However, the implantation depth of heavy ions and neutrons is only about 1 μm from the surface, and when neutrons are implanted, there is a safety problem that the superconductor becomes radioactive. Absent.

[0007]

In view of the above problems, the present invention provides a copper oxide superconductor having a long superconducting coherence length in the c-axis direction, a small superconducting anisotropy, and a spin quantum defect. Irreversible magnetic field Hi
It is an object of the present invention to provide a quantum defect flux pinned superconducting material having a high rr, a critical current density Jc, and a superconducting transition temperature Tc, and a method for manufacturing the same.

[0008]

In order to solve the above problems, the quantum defect magnetic flux pinned superconducting material of the present invention comprises a spin, spin interaction, exchange interaction, superexchange interaction, and / or In a copper oxide superconductor in which the spin fluctuation effect is a major part of the superconducting mechanism, ions having no spin, vacancies, and ions in different spin states are present at crystal lattice points of Cu ions and / or O ions having spin. ,
And / or a spin quantum defect consisting of a lattice defect, and the spin quantum defect forms a non-superconducting phase or a low superconducting transition temperature phase in a region of about the superconducting coherence length. It is characterized by acting as a pinning center.

In the above structure, preferably, ions having no spin, such as Mg, Zn,
It has Ag or Au. Preferred examples of the present invention, the composition formula _{Cu 1-x M x (Ba} 1-y Sr y) 2 (Ca
_{1-z Mg z) n-} 1 (Cu 1-w Z w) n O 2 + nv ( wherein,
M = T1, Hg, Bi, Pb, Au, In, Sn, M
g, Ag, Mo, W, Re, Os, Ti, Cr, V, F
e, Ni _, one or more elements of _the lanthanide series elements, Z = Zn, one or more elements of Ti, Cr, V, Fe, Ni, 0 ≦ x <1, 0 ≦ y ≦ 1, 0 ≦ z < 1,
It is a copper oxide superconductor having a spin quantum defect represented by 0 ≦ w ≦ 0.1, 0 ≦ v ≦ 4, 3 ≦ n ≦ 16). As another preferred example, the composition formula Cu _1-x M _x (Ba _1-y S
_{r y) 2 (Ca 1-} z Mg z) n-1 (Cu 1-w Mg w) n
O _{2 + nv} (where M = Tl, Hg, Bi, Pb, A
u, In, C, Sn, Mg, Ag, Mo, W, Re, O
s, Ti, Cr, V, Fe, Ni _, one or more lanthanide series elements, 0 ≦ x <1, 0 ≦ y ≦ 1,0
≦ z <1, 0 ≦ w ≦ 0.1, 0 ≦ v ≦ 4, 3 ≦ n ≦ 1
It is a copper oxide superconductor having a spin quantum defect represented by 6).

As another preferred example, the composition formula Cu _1-x M
_{x (Ba 1-y Sr y} ) 2 (Ca 1-z Mg z) n-1 (Cu
_{1-w Zw} ) _n (O _1-f F _f ) _{2 + nv} (where M = Tl,
Hg, Bi, Pb, Au, In, Sn, Mg, Ag, M
o, W, Re, Os, Ti, Cr, V, Fe, Ni _, one or more lanthanide series elements, Z = Mg,
One or more elements of Zn, Ti, Cr, V, Fe, Ni, 0 ≦ x <1, 0 ≦ y ≦ 1, 0 ≦ z <1, 0 ≦ w ≦
0.1,0 ≦ f ≦ 1,0 ≦ v ≦ 4,3 ≦ n ≦ 16) is a copper oxide superconductor having a spin quantum defect.

According to another aspect of the invention, a spin quantum
The copper oxide superconductor having defects has a composition formula of Cu_1-xM
_x(Ba_1-ySr_y)_Two(Ca_1-zMg_z)_n-1(Cu
_1-wMg_w)_n(O_1-fF_f)_{2 + nv}(Where M = T
1, Hg, Bi, Pb, Au, In, Sn, Mg, A
g, Mo, W, Re, Os, Ti, Cr, V, Fe, N
i _,One or more lanthanide series elements, 0 ≦
x <1,0 ≦ y ≦ 1,0 ≦ z <1,0 ≦ w ≦ 0.1,0
≦ f ≦ 1, 0 ≦ v ≦ 4, 3 ≦ n ≦ 16)
It is characterized by. Further, the composition formula Cu_1-xC_xBa_Two(Ca
_1-zMg_z)_Three(Cu_1-wMg_w)_FourO₉(Where x =
0.3, z = 0.1, 0.2, w = 0.01, 0.0
Copper oxide superconductivity with spin quantum defect represented by 2)
The body is also preferred. Also, a copper oxide having a spin quantum defect
The superconducting anisotropy γ of the superconductor (γ = ξab / ξc.
Where ξab is the superconducting coherence length in the ab axis plane,
ξc is the superconducting coherence length in the c-axis direction) is 1 to 4.
Lower than conventional copper oxide superconductors
I do. Furthermore, copper oxide superconductivity with spin quantum defects
The coherence length Δc in the c-axis direction of the body is 0.6 to 2.0 n
m, which is longer than the conventional copper oxide superconductor.
Features.

According to the above configuration, the spin of Cu near the lattice point having no spin is largely polarized by the spin interaction, and the magnetic field due to the polarization destroys the superconducting electron pairs in this region, and this region becomes non-polar. Since a superconducting phase or a superconducting phase having a low superconducting transition temperature is formed, magnetic flux easily enters, and a region near a lattice point having no spin acts as a magnetic flux pinning center. In addition, the existence of such a spin quantum defect increases the superconducting coherence length in the c-axis direction, and as a result, the superconducting anisotropy decreases. Furthermore, the quantum defect magnetic flux pinned type superconducting material having these structures can make the superconducting layer thick and the charge supply layer thin, so that the superconducting coherence length in the c-axis direction can be further increased, The conduction anisotropy is further reduced.

Further, according to a preferred embodiment of the present invention, a copper oxide superconductor having a spin quantum defect, carbonic acid (CO ₃ )
It is characterized in that the concentration is 1 mol% or less and there is no weak bonding of the grain boundaries due to the CO ₃ precipitate due to the effect of the low CO ₃ concentration. According to this configuration, since the superconducting state is prevented from being broken due to the weak coupling of the grain boundaries of the superconductor crystal grains, the irreversible magnetic field Hirr can be obtained even with a quantum defect magnetic flux pinned superconducting material made of polycrystal. , High critical current density Jc and superconducting transition temperature Tc, and can be used as a quantum defect magnetic flux pinned superconducting material. Further, a copper oxide superconductor having a spin quantum defect is overdoped, and there is no superconducting weak coupling at a superconductor grain boundary due to an effect of suppressing band bending due to overdoping.

According to this configuration, the superconducting wave derivative is connected well between the superconductor grains, and even if the quantum defect magnetic flux pinned type superconducting material made of polycrystal is used, the irreversible magnetic field Hirr and the critical current It can be used as a quantum defect magnetic flux pinned superconducting material having a high density Jc and a high superconducting transition temperature Tc. In the present invention, the copper oxide superconductor having a spin quantum defect is selectively over-doped, and the selective over-doping effect (see the international publication WO00 / 58218, 2000 by the present inventors).
(See page 7 of the specification published internationally on October 5, 1998)
Is characterized by a high superconducting transition temperature and a high superconducting critical current density. Further, in the present invention, the copper oxide superconductor having a spin quantum defect is over-doped to form d + is superconducting symmetry, so that the superconductivity in the CuO ₂ plane due to the d + is superconducting symmetry is obtained. The superconducting anisotropy is further reduced by the effect of reducing the conductive anisotropy and the above-described effect of reducing the superconducting anisotropy. According to the above configuration, the irreversible magnetic field Hir is even higher.
A quantum defect magnetic flux pinned superconducting material having r, critical current density Jc and superconducting transition temperature Tc is obtained.

Further, one embodiment of the method of manufacturing a quantum defect magnetic flux pinned superconducting material according to the present invention is to provide a method for manufacturing a material having a composition of a copper oxide superconductor having a spin quantum defect on a single crystal substrate or a crystal orientation substrate. And sealed in an Ag, Au or oxidation-resistant container, and controlled in pressure, temperature and time from 0.1 atm to tens of thousands of atm, non-orientation, c-axis orientation or biaxial orientation of a and c axes Of the critical current density J
c, forming a bulk or single crystal having a high irreversible magnetic field Hirr and a high superconducting transition temperature. Another aspect of the method for producing a quantum defect magnetic flux pinned superconducting material of the present invention is to deposit a material having a composition of a copper oxide superconductor having a spin quantum defect on a single crystal substrate or a crystallographically oriented substrate. Or, by coating and enclosing in an Ag or oxidation-resistant container, and controlling the temperature and time under a low pressure of 0.1 to 10 atm, non-oriented, c-axis oriented, or biaxially oriented a, c-axis oriented crystal growth Is performed to produce a polycrystalline or single-crystal film having a high critical current density Jc, an irreversible magnetic field Hirr, and a high superconducting transition temperature.

Further, in another embodiment of the method for producing a quantum defect magnetic flux pinned superconducting material according to the present invention, there is provided a raw material having a composition of a copper oxide superconductor having a spin quantum defect or a copper oxide having a spin quantum defect. The superconducting material is sealed in an Ag or oxidation-resistant metal container, and rolling and annealing are combined,
By performing non-oriented, c-axis oriented, or biaxially oriented crystal growth of the a and c axes, the spin quanta that are arranged perpendicularly to the CuO ₂ plane of the superconducting layer and one-dimensionally or connected in a string shape. By introducing defects, a polycrystalline body having a high critical current density Jc, an irreversible magnetic field Hirr, and a high superconducting transition temperature and capable of being processed into a thin wire or tape is manufactured. According to this configuration, spin quantum defects arranged one-dimensionally in the c-axis direction or connected in a string shape can be introduced, and magnetic flux easily enters the crystal.

According to the above-described configurations of the present invention, it is possible to manufacture a quantum defect magnetic flux pinned superconducting material suitable for various uses at an extremely low cost.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a crystal model of a quantum defect magnetic flux pinned superconducting material of the present invention. As shown in FIG. 1, the quantum defect magnetic flux pinned superconducting material according to the present invention introduces spin quantum defects such as Mg and F ions having no spin into crystal lattice points of Cu and O having spin. , The region of about the coherence length is changed to a non-superconducting phase or a low Tc (superconducting transition temperature) phase, and this phase is contributed as a pinning center for trapping magnetic flux, and a high critical current density Jc and a high irreversible magnetic field Hir
r is achieved. Further, by increasing the number n of the superconducting layers of the layered superconductor and increasing the thickness of the superconducting layer, the uncertainty region of the superconducting electrons in the c-axis direction expands in the thickness direction, and the c-axis Since the coherence length Δc in the direction can be increased, the superconducting anisotropy γ can be extremely reduced, and the critical current density Jc and the irreversible magnetic field Hirr can be increased.

Further, since the element constituting the charge supply layer is Cu or O which can generate superconductivity, the charge supply layer can be metallized or made superconductive. According to the uncertainty principle, the superconducting coherence length is proportional to the Fermi velocity VF. Thus, by metallizing or superconducting the charge supply layer, the VF component in the c-axis direction is increased, and the coherence length ξ
c can be lengthened, and the superconducting anisotropy can be further reduced.

FIG. 2 is a diagram showing the principle of the magnetic flux pinning action by the spin quantum defect of the quantum defect magnetic flux pinned superconducting material of the present invention. In FIG. 2A, lattice points indicate crystal lattice points in the ab-axis plane of the superconducting material, and small arrows indicate spins of Cu atoms or O atoms. The arrows facing each other indicate the spins of the superconducting electron pairs. Large hollow circles indicate a state in which Cu ions are replaced by Mg ions having no spin. The spin of the Cu atom around the Mg ion without the spin is largely polarized by spin interaction, and its direction is aligned in a certain direction. This polarization is indicated by the large arrow. In the present invention, this defect is defined as a spin quantum defect. The superconducting electron pair near the polarization is destroyed by the magnetic field of the polarization and becomes a non-superconducting state or a superconducting phase having a low superconducting transition temperature, so that magnetic flux easily penetrates and acts as a magnetic flux pinning center. FIG. 2B is a diagram showing a cross section perpendicular to the b-axis of the quantum defect magnetic flux pinned superconducting material. This figure shows a state in which superconducting layers are stacked in the c-axis direction, and spin quantum defects of each superconducting layer are one-dimensionally arranged or connected in the c-axis direction. According to this configuration,
The magnetic field in the c-axis direction enters from the upper surface or the lower surface perpendicular to the c-axis direction of the superconducting material and exits from the lower surface or the upper surface, so that the magnetic flux can enter and the magnetic flux is fixed.

[0021] Preferred examples of the quantum defect flux pinning superconducting material of the present invention, the superconductor having a two-dimensional layered structure, composition formula _{Cu 1-x M x (Ba} 1-y Sr y) ₂ (Ca _1-z Mg _z )
_{n-1 (Cu 1-w} Mg w) n (O 1-f F f) can be described in 2 _{+ nv} can be mentioned copper oxide superconductors.
Where M = Tl, Hg, Bi, Pb, Au, I
n, Sn, Mg, Ag, Mo, W, Re, Os, Ti,
Cr, V, Fe, Ni _, one or more lanthanide series elements, 0 ≦ x <1, 0 ≦ y ≦ 1, 0 ≦ z <
1,0 ≦ w ≦ 0.1,0 ≦ f ≦ 1,0 ≦ v ≦ 4,3 ≦
It is represented by n ≦ 16.

In the case of this copper oxide superconductor, the superconducting layer
There (Ca_1-zMg_z)_n-1(Cu _1-wMg_w)_n(O
_1-fF_f)_{2 + n}Increase in the number of layers n, joining the superconducting layers
Charge supply layer Cu_1-xM_x(Ba_1-ySr_y)_Two(O
_1-fF_f)_4-vSuperconductivity due to the proximity effect of
Superconductivity in the c-axis direction due to the intrinsic superconductivity of the charge supply layer
Inductive coupling can be further enhanced. As a result, c-axis
The uncertain region (thickness) of superconducting electrons in the direction expands,
レ ン ス c increases, the superconductivity anisotropy decreases,
The critical current density Jc and the irreversible magnetic field Hirr increase.

In particular, in the case of some copper oxide superconductors, the coherence length Δc is empirically determined, where n is the number of superconducting layers, Δc = 0.32 (n−1) nm, Δab = 1. 6n
m, the superconducting anisotropy γ is given by γ = {ab / ξ
c = 5 / (n-1), and in a superconductor having n of 3 or more, if the carrier concentration is sufficient, superconducting anisotropy γ <2 can be realized, and the critical current density Jc and the irreversible magnetic field Hirr are increased. be able to. Hirr the semi-empirical equation from the value of the upper critical magnetic field _{Hc 2: Hirr = Hc 2 (} 1- (T / T
c) ²⁾ / gamma but experimental values according to the ^two well described, gamma
If <2, a high value of Hirr = 40T is predicted at 77K in the Cu-1234 crystal structure system.

Further, in the above copper oxide superconductor, Cu
Is the average valence of Z = 2 + (4-2v) / (n + 1) <2+
4 / (n + 1), and Z is 2.25 or more from n = 1 to 16. Therefore, by lowering the oxygen vacancy concentration v, superconducting anisotropy γ <2 can be realized, It is possible to supply a carrier sufficient to increase the critical current density Jc and the irreversible magnetic field Hirr.

In order for the spin quantum defect magnetic flux pinning effect of the present invention to work effectively, (1) quantum defects must be continuously connected one-dimensionally and introduced perpendicularly to the CuO ₂ plane; ) Both ends of the one-dimensionally connected defect are exposed to a magnetic field, and magnetic flux easily penetrates; (3) the coherence length of the superconducting material in the c-axis direction is long; The most desirable condition is that it is conductive, and (5) if the charge supply layer does not have superconductivity, its thickness is as thin as possible.

The method for producing the quantum defect magnetic flux pinned type superconducting material of the present invention includes a closed type low pressure method, a high pressure synthesis method, a hot press method, a HIP method (high temperature hydrostatic pressure treatment method), and a sealing method using an oxidation resistant material. A non-equilibrium manufacturing method such as a sputtering method is used. In a closed low-pressure method, a high-pressure synthesis method, a hot press method, a HIP method (high-temperature hydrostatic pressure treatment method), or a sealing method using an oxidation-resistant material, the above-described quantum defect magnetic flux pinned superconducting material or its raw material is used, for example. , SrTiO ₃ , NdGa
O ₃ , LaAlO ₃ , YSZ (Y-stabilized ZrO ₂ ), L
aSrGaO ₄ single crystal substrate or crystal oriented film substrate is deposited or coated and sealed in a container of oxidation-resistant material, and by controlling pressure, temperature and time, non-oriented, c-axis oriented or a, c-axis oriented Can be produced. Thus, a polycrystalline or single-crystal film having a high critical current density Jc and a high irreversible magnetic field Hirr can be easily manufactured depending on the application.

The above quantum defect magnetic flux pinned superconducting material or its raw material is placed on the above-mentioned single crystal substrate or crystal orientation film substrate, and gold, silver, or inconel, hastelloy, alumina, AIN, By enclosing in an oxidation-resistant metal such as BN or a ceramic container, and controlling the pressure, temperature and time, it is possible to obtain a non-oriented, c-axis oriented, or a, c
Crystals with biaxial orientation can be produced. Thereby, depending on the application, a high critical current density Jc and a high irreversible magnetic field H
A polycrystalline or single crystal film having irr can be easily manufactured. Unoriented or c-axis oriented, or a,
A polycrystalline bulk or single crystal having a high critical current density Jc and a high irreversible magnetic field Hirr can be easily produced by biaxially orienting the c-axis.

In the sputtering method, a sintered body having the same composition as that of the quantum defect magnetic flux pinned type superconducting material to be manufactured may be used as a target, or a target for each element may be used to laminate each atomic layer. May be. The sputtering method is, for example, SrTiO ₃ , NdGaO ₃ , La
AlO ₃ , YSZ (Y-stabilized ZrO ₂ ), LaSrGa
This is performed using an O ₄ single crystal substrate under the conditions of a substrate temperature of 300 to 800 ° C. and an oxygen gas pressure of 0.001 to 1 Torr.

Next, an embodiment of the present invention will be described. Embodiment 1 FIG. Mg-doped Cu-1234 crystal structure
A quantum defect magnetic flux pinned superconducting material was fabricated and
The properties were measured. Charge composition, Cu_1-xC_xBa_Two(Ca
_1-zMg_z)_Three(Cu_1-wMg_w)_FourO₉(Where x =
0.3, z = 0.1, w = 0.01)
Formed Cu _1-xC_xBa_Two(Ca_1-zMg_z)_Three(Cu_1-w
Mg_w)_FourO₉(Where x = 0.3, z = 0.2, w =
0.02) with CuO, AgCO_Three, With oxidants
And add AgO at 1000 ° C. under a pressure of 3 GPa.
By heating for 2 hours, two kinds of different compositions
A quantum defect flux pinned superconducting material was fabricated. 2 above
The types of quantum defect flux pinned superconducting materials
Also has superconductivity equivalent to superconductors of the same composition without Mg
The transition temperature was 116 to 117K.

The magnetization characteristics of the c-axis oriented powder sample were
The temperature change was measured (magnetic field intensity range 0.1-5T). Magnetic
Of the upper critical magnetic field Hc_TwoThe temperature change of
Hc_TwoThe superconducting anisotropy is γ
= 1.4 to 1.5. Also the magnetization
From the extrapolated value of temperature change, (Hc_Two) Ab = 103-127
T, (Hc _Two) It was confirmed that c = 74-86T.
Was. These upper critical magnetic fields and Ginzburg-La
ndau equation, (Hc_Two) Ab = φ₀/ 2π {ab}
c, (Hc_Two) C = φ₀/ 2πξabξab, (φ₀:
(Flux quantum), the coherence length is given by {c = 1.
3 to 1.4 nm, Δab = 1.9 to 2.0 nm.
I understood. Therefore, this quantum defect flux pinning
The superconducting anisotropy γ of the type superconducting material is 1.4 to 1.5.
You. On the other hand, the same composition and the same crystal structure without Mg doping
The superconducting anisotropy γ of the (Cu-1234 type) superconductor is
Since it is 1.6, the superconducting anisotropy is reduced. Ma
The coherence of this quantum defect flux pinned superconducting material
長 c = 1.3-1.4 nm, ξab = 1.9
２．０2.0 nm. On the other hand, the same group without Mg doping
Of superconductor with the same crystal structure (Cu-1234 type)
The coherence length is Δc = 1.0 nm, Δab = 1.6 n
m, both coherence lengths increase. You
In other words, the superconductivity of this quantum defect magnetic flux pinned superconducting material
Improvements in conductivity anisotropy and superconducting coherence length are
This can be attributed to the introduction of spin quantum defects by the step. Ma
Magnetization (M) -magnetic field (H) determined from a hysteresis curve
The irreversible magnetic field Hirr was 8T at 77K.

The formation of the quantum defect pinning center by Mg doping has increased the coherence length and reduced the superconducting anisotropy. Nevertheless, Hirr does not become as large as expected because despite the formation of the quantum defect flux pinning center, both ends do not reach the surface so as to be exposed to the magnetic field, so the superconductivity is high. This is probably because the magnetic flux is hardly penetrated by being shielded by the phase. It is necessary to form a one-dimensional quantum defect flux pinning center that reaches the surface.

[0032]

The quantum defect pinned type superconducting material of the present invention has a magnetic flux pinning effect due to spin quantum defects, and has a superconducting anisotropy γ = 1.4, which was impossible in the past. Superconducting coherence length, Δab = 2.0 nm, Δc =
1.4 nm, so that the irreversible magnetic field Hir
It can be used as a superconducting material having a high r. As a predicted value, a high irreversible magnetic field Hirr of 30 T or more at 77K can be expected. This superconducting material has a higher superconducting critical current density Jc and a higher irreversible magnetic field Hir than ever before.
In addition to the material having r, the superconducting anisotropy exhibits low anisotropy close to isotropic, so that the alignment control conditions at the time of manufacturing can be relaxed. Since the orientation control condition can be relaxed, it is possible to produce a superconducting wire having no orientation and the highest performance at a low cost by using the method for producing a quantum defect pinned type superconducting material of the present invention. it can. In addition, it can be used as a bulk material and an element material as a high-temperature superconducting material having the highest level of performance as a superconductor. The results disclosed in the present invention support that spin and spin interaction are a major part of the superconducting mechanism in a copper oxide superconductor. The fact that the pinning center of magnetic flux can be formed by introducing spin quantum defects has given momentum to the development of a new method of introducing a magnetic flux pinning mechanism of the quantum defect introduction type in the future. The results also provide important guidance for elucidating the superconducting mechanism. That is, conventionally, it has been commonly accepted that a high superconducting transition temperature Tc is closely related to a high superconducting anisotropy, but the superconductor of the present invention has a low anisotropy high temperature superconductivity close to isotropic. High superconducting transition temperature Tc despite being a conductor
Therefore, these common senses are violated, and have a great academic and engineering impact.

[Brief description of the drawings]

FIG. 1 is a diagram showing a crystal model of a quantum defect magnetic flux pinned type superconducting material of the present invention.

FIG. 2 is a diagram showing the principle of the magnetic flux pinning action of the quantum defect magnetic flux pinned type superconducting material of the present invention by the spin quantum defect.

Claims (16)

[Claims] 1. A copper oxide superconductor in which spin, spin interaction, exchange interaction, super-exchange interaction, and / or spin fluctuation effect is a main part of the superconducting mechanism. And / or a spin quantum defect consisting of a non-spin ion, a vacancy, an ion in a different spin state, and / or a lattice defect at a crystal lattice point of the O ion, and the spin quantum defect has a superconducting coherence length. A quantum defect magnetic flux pinned superconducting material, characterized in that the spin quantum defect acts as a magnetic flux pinning center due to the effect of forming a non-superconducting phase or a low superconducting transition temperature phase in a degree region. 2. The quantum defect magnetic flux pinned high-performance supercharger according to claim 1, wherein said Cu ion has a non-spin ion Mg, Zn, Ag, or Au at a crystal lattice point. Conductive material. Wherein said copper oxide superconductor having a spin quantum defect, composition formula _{Cu 1-x M x (Ba} 1-y Sr y) 2 (Ca 1-z M
_{g z) n-1 (Cu} 1-w Z w) n O 2 + nv ( where, M = T
1, Hg, Bi, Pb, Au, In, C, Sn, Mg,
Ag, Mo, W, Re, Os, Ti, Cr, V, Fe,
Ni, one or more lanthanide series elements, Z
= One or more elements of Zn, Ti, Cr, V, Fe, Ni, 0 ≦ x <1, 0 ≦ y <1, 0 ≦ z <1, 0 ≦ w
<0.1, 0 ≦ v ≦ 4, 3 ≦ n ≦ 16), wherein the quantum defect magnetic flux pinned superconducting material according to claim 1 or 2, characterized in that: Wherein said copper oxide superconductor having a spin quantum defect, composition formula _{Cu 1-x M x (Ba} 1-y Sr y) 2 (Ca 1-z M
_{g z) n-1 (Cu} 1-w Mg w) n O 2 + nv ( where, M =
Tl, Hg, Bi, Pb, Au, In, C, Sn, M
g, Ag, Mo, W, Re, Os, Ti, Cr, V, F
e, Ni, one or more lanthanide series elements, 0 ≦ x <1, 0 ≦ y <1, 0 ≦ z <1, 0 ≦ w <
The quantum defect magnetic flux pinned superconducting material according to claim 1, wherein 0.1, 0 ≦ v ≦ 4, 0 ≦ v ≦ 4, 3 ≦ n ≦ 16). Wherein said copper oxide superconductor having a spin quantum defect, composition formula _{Cu 1-x M x (Ba} 1-y Sr y) 2 (Ca 1-z M
g _z ) _n-1 (Cu _1-w Z _w ) _n (O _1-f F _f )
_{2 + nv} (where M = Tl, Hg, Bi, Pb, Au, I
n, C, Sn, Mg, Ag, Mo, W, Re, Os, T
i, Cr, V, Fe, Ni, one or more lanthanide series elements, Z = Mg, Zn, Ti, Cr, V,
One or more elements of Fe and Ni, 0 ≦ x <1,0 ≦
y <1,0 ≦ z <1,0 ≦ w <0.1,0 ≦ f ≦ 1,0
.Ltoreq.v.ltoreq.4, 3.ltoreq.n.ltoreq.16), wherein the quantum defect magnetic flux pinned superconducting material according to claim 1 or 2, is provided. Wherein said copper oxide superconductor having a spin quantum defect, composition formula _{Cu 1-x M x (Ba} 1-y Sr y) 2 (Ca 1-z M
g _z ) _n-1 (Cu _1-w Mg _w ) _n (O _1-f F _f ) _{2 + nv}
(Where M = Tl, Hg, Bi, Pb, Au, In,
C, Sn, Mg, Ag, Mo, W, Re, Os, Ti,
One or more elements of Cr, V, Fe, Ni, lanthanide series elements, 0 ≦ x <1, 0 ≦ y <1, 0 ≦ z <1,
0 ≦ w <0.1, 0 ≦ f ≦ 1, 0 ≦ v ≦ 4, 3 ≦ n ≦ 1
3. The quantum defect magnetic flux pinned superconducting material according to claim 1, wherein the material can be described in 6). 7. The copper oxide superconductor having the spin quantum defect has a composition formula of Cu _1-x C _x Ba ₂ (Ca _1-z Mg _z ) ₃ (Cu
_1-w Mg _w ) ₄ O ₉ (where x = 0.3, z = 0.1,
3. The quantum defect magnetic flux pinned superconducting material according to claim 1, wherein 0.2, w = 0.01, 0.02). 8. The superconducting anisotropy γ of the copper oxide superconductor having the spin quantum defect (γ = ξab / ξc, where ξab is the superconducting coherence length in the ab axis plane, ξc
Has a superconducting coherence length in the c-axis direction) of 1 to 4,
The quantum defect magnetic flux pinned superconducting material according to claim 1, wherein the material has low anisotropy. 9. The coherence length Δc in the c-axis direction of the copper oxide superconductor having the spin quantum defect is 0.6.
The quantum defect magnetic flux pinned superconducting material according to any one of claims 1 to 8, wherein the coherence length is long. Wherein said spin carbonate of the copper oxide superconductors having a quantum defect (CO ₃₎ concentration of not more than 1 mol%, this CO ₃ concentration is less effective, the grain boundary due to CO ₃ precipitation 10. The quantum defect magnetic flux pinned superconducting material according to claim 1, wherein there is no weak coupling. 11. The copper oxide superconductor having the spin quantum defect is overdoped, and the superconducting grain boundary has no superconducting weak coupling due to an effect of suppressing band bending due to the overdoping. The quantum defect magnetic flux pinned superconducting material according to any one of claims 1 to 10, characterized in that: 12. The copper oxide superconductor having the spin quantum defect is selectively overdoped, and the superconducting transition temperature is high and the superconducting critical current density is high due to the selective overdoping effect. The quantum defect magnetic flux pinned superconducting material according to any one of claims 1 to 11, characterized in that: 13. The copper oxide superconductor having the spin quantum defect is overdoped to form a d + is wave superconducting symmetry, and the d + is wave superconducting symmetry in the CuO ₂ plane The quantum defect magnetic flux according to any one of claims 1 to 12, wherein the superconducting anisotropy is low due to the effect of reducing the superconducting anisotropy and the effect of the superconducting anisotropy being low. Pinned superconducting material. 14. A raw material having a composition of a copper oxide superconductor having a spin quantum defect is placed on a single crystal substrate or a crystallographically oriented substrate, and sealed in an Ag, Au, or oxidation-resistant container.
Critical current density Jc, irreversible magnetic field by controlling the pressure, temperature and time from 0.1 atm to tens of thousands of atmospheres to grow crystals in non-orientation, c-axis orientation, or biaxial orientation of a and c axes A method for producing a quantum defect magnetic flux pinned superconducting material, characterized by forming a bulk or single crystal having a high Hirr and a high superconducting transition temperature Tc. 15. A raw material having a composition of a copper oxide superconductor having a spin quantum defect is deposited or coated on a single crystal substrate or a crystallographically oriented substrate, and sealed in an Ag or oxidation-resistant container. Critical current density Jc, irreversible magnetic field Hirr, and superconducting transition by controlling temperature and time under low pressure of 10 to 10 atm and performing crystal growth of non-orientation, c-axis orientation or biaxial orientation of a and c axes. A method for producing a quantum defect magnetic flux pinned superconducting material, comprising producing a polycrystalline or single crystal film having a high temperature Tc. 16. Rolling and annealing a raw material having a composition of a copper oxide superconductor having a spin quantum defect or a copper oxide superconducting material having a spin quantum defect is enclosed in an Ag or oxidation-resistant metal container. By performing non-oriented, c-axis oriented, or biaxially oriented a, c-axis crystal growth in combination with the superconducting layer perpendicular to the CuO ₂ plane and one-dimensionally or in a string form. Introducing a connected spin quantum defect, producing a polycrystalline material having a high critical current density Jc, an irreversible magnetic field Hirr, and a high superconducting transition temperature Tc, and which can be processed into a thin wire or tape; A method for producing a quantum defect magnetic flux pinned superconducting material.