High-temperature superconductivity
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High-temperature superconductors (high-Tc or HTS) are defined as materials with critical temperature (the temperature below which the material behaves as a
The major advantage of high-temperature superconductors is that they can be cooled using liquid nitrogen,[2] in contrast to the previously known superconductors that require expensive and hard-to-handle coolants, primarily liquid helium. A second advantage of high-Tc materials is they retain their superconductivity in higher magnetic fields than previous materials. This is important when constructing superconducting magnets, a primary application of high-Tc materials.
The majority of high-temperature superconductors are
The main class of high-temperature superconductors is copper oxides combined with other metals, especially the rare-earth barium copper oxides (REBCOs) such as yttrium barium copper oxide (YBCO). The second class of high-temperature superconductors in the practical classification is the iron-based compounds.[8][9] Magnesium diboride is sometimes included in high-temperature superconductors: It is relatively simple to manufacture, but it superconducts only below 39 K (−234.2 °C), which makes it unsuitable for liquid nitrogen cooling. Some extremely high-pressure superhydride compounds are usually categorized as high-temperature superconductors. In fact, many articles on high-temperature superconductors can be found on this research on high-pressure gases, which are not suitable for practical applications. The current Tc record holder is claimed to be carbonaceous sulfur hydride, however superconductivity in these compounds has come under question,[10] and the discovery paper has been retracted due to credible accusations of data manipulation.[11]
History
Superconductivity was discovered by
In 1986, at the IBM research lab near Zürich in Switzerland, Bednorz and Müller were looking for superconductivity in a new class of ceramics: the copper oxides, or cuprates.
Bednorz encountered a particular copper oxide whose resistance dropped to zero at a temperature around 35.1 K (−238 °C).
In 1987, Philip W. Anderson gave the first theoretical description of these materials, based on the resonating valence bond (RVB) theory,[16] but a full understanding of these materials is still developing today. These superconductors are now known to possess a d-wave[clarification needed] pair symmetry. The first proposal that high-temperature cuprate superconductivity involves d-wave pairing was made in 1987 by N. E. Bickers, Douglas James Scalapino and R. T. Scalettar,[17] followed by three subsequent theories in 1988 by Masahiko Inui, Sebastian Doniach, Peter J. Hirschfeld and Andrei E. Ruckenstein,[18] using spin-fluctuation theory, and by Claudius Gros, Didier Poilblanc, Maurice T. Rice and FC. Zhang,[19] and by Gabriel Kotliar and Jialin Liu identifying d-wave pairing as a natural consequence of the RVB theory.[20] The confirmation of the d-wave nature of the cuprate superconductors was made by a variety of experiments, including the direct observation of the d-wave nodes in the excitation spectrum through angle resolved photoemission spectroscopy (ARPES), the observation of a half-integer flux in tunneling experiments, and indirectly from the temperature dependence of the penetration depth, specific heat and thermal conductivity.
As of 2021,[21] the superconductor with the highest transition temperature at ambient pressure is the cuprate of mercury, barium, and calcium, at around 133 K (−140 °C).[22] There are other superconductors with higher recorded transition temperatures – for example lanthanum superhydride at 250 K (−23 °C), but these only occur at very high pressures.[23]
The origin of high-temperature superconductivity is still not clear, but it seems that instead of electron–phonon attraction mechanisms, as in conventional superconductivity, one is dealing with genuine electronic mechanisms (e.g. by antiferromagnetic correlations), and instead of conventional, purely s-wave pairing, more exotic pairing symmetries are thought to be involved (d-wave in the case of the cuprates; primarily extended s-wave, but occasionally d-wave, in the case of the iron-based superconductors).
In 2014, evidence showing that fractional particles can happen in quasi two-dimensional magnetic materials, was found by École Polytechnique Fédérale de Lausanne (EPFL) scientists[24] lending support for Anderson's theory of high-temperature superconductivity.[25]
Selected list of superconductors
Tc respectively
boiling point |
Pressure | Material | Notes | |
---|---|---|---|---|
in K | in °C | |||
273.15 | 0 | 100 kPa
|
Ice: Melting point at atmospheric pressure (common cooling agent; for reference) | |
250 | −23 | 170 GPa
|
LaH10[27] | Metallic superconductor with one of the highest known critical temperatures |
203 | −70 | 155 GPa | High pressure phase of hydrogen sulfide (H2S) | Mechanism unclear, observable isotope effect[28] |
194.6 | −78.5 | 100 kPa | Carbon dioxide (dry ice): Sublimation point at atmospheric pressure (common cooling agent; for reference) | |
138 | −135 | Hg12Tl3Ba30Ca30Cu45O127[21] | High-temperature superconductors with copper oxide with relatively high critical temperatures | |
110 | −163 | Bi2Sr2Ca2Cu3O10 (BSCCO) | ||
92 | −181 | YBa2Cu3O7 (YBCO) | ||
87 | −186 | 100 kPa | Argon: Boiling point at atmospheric pressure (common cooling agent; for reference) | |
77 | −196 | 100 kPa | Nitrogen: Boiling point at atmospheric pressure (common cooling agent; for reference) | |
45 | −228 | SmFeAsO0.85F0.15 | Low-temperature superconductors with relatively high critical temperatures | |
41 | −232 | CeOFeAs | ||
39 | −234 | 100 kPa | MgB2 | Metallic superconductor with relatively high critical temperature at atmospheric pressure |
30 | −243 | 100 kPa | La2−xBaxCuO4[29] | First high-temperature superconductor with copper oxide, discovered by Bednorz and Müller |
27 | −246 | 100 kPa | Neon: Boiling point at atmospheric pressure (common cooling agent; for reference) | |
21.15 | −252 | 100 kPa | Hydrogen: Boiling point at atmospheric pressure (common cooling agent; for reference) | |
18 | −255 | Nb3Sn[29] | Metallic low-temperature superconductors with technical relevance | |
9.2 | −264.0 | NbTi[30] | ||
4.21 | −268.94 | 100 kPa | Helium: Boiling point at atmospheric pressure (common cooling agent of low temperature physics; for reference) | |
4.15 | −269.00 | Hg (Mercury)[31] | Metallic low-temperature superconductors | |
1.09 | −272.06 | Ga (Gallium)[31] |
Properties
The "high-temperature" superconductor class has had many definitions.
The label high-Tc should be reserved for materials with critical temperatures greater than the boiling point of liquid nitrogen. However, a number of materials – including the original discovery and recently discovered pnictide superconductors – have critical temperatures below 77 K (−196.2 °C) but nonetheless are commonly referred to in publications as high-Tc class.[32][33]
A substance with a critical temperature above the boiling point of liquid nitrogen, together with a high critical magnetic field and critical current density (above which superconductivity is destroyed), would greatly benefit technological applications. In magnet applications, the high critical magnetic field may prove more valuable than the high Tc itself. Some cuprates have an upper critical field of about 100 tesla. However, cuprate materials are brittle ceramics that are expensive to manufacture and not easily turned into wires or other useful shapes. Furthermore, high-temperature superconductors do not form large, continuous superconducting domains, rather clusters of microdomains within which superconductivity occurs. They are therefore unsuitable for applications requiring actual superconductive currents, such as magnets for magnetic resonance spectrometers.[34] For a solution to this (powders), see HTS wire.
There has been considerable debate regarding high-temperature superconductivity coexisting with magnetic ordering in YBCO,[35] iron-based superconductors, several ruthenocuprates and other exotic superconductors, and the search continues for other families of materials. HTS are Type-II superconductors, which allow magnetic fields to penetrate their interior in quantized units of flux, meaning that much higher magnetic fields are required to suppress superconductivity. The layered structure also gives a directional dependence to the magnetic field response.
All known high-Tc superconductors are Type-II superconductors. In contrast to
Cuprates
Cuprates are layered materials, consisting of superconducting layers of copper oxide, separated by spacer layers. Cuprates generally have a structure close to that of a two-dimensional material. Their superconducting properties are determined by electrons moving within weakly coupled copper-oxide (CuO2) layers. Neighbouring layers contain ions such as lanthanum, barium, strontium, or other atoms which act to stabilize the structures and dope electrons or holes onto the copper-oxide layers. The undoped "parent" or "mother" compounds are Mott insulators with long-range antiferromagnetic order at sufficiently low temperatures. Single band models are generally considered to be enough to describe the electronic properties.
The cuprate superconductors adopt a perovskite structure. The copper-oxide planes are checkerboard lattices with squares of O2− ions with a Cu2+ ion at the centre of each square. The unit cell is rotated by 45° from these squares. Chemical formulae of superconducting materials generally contain fractional numbers to describe the doping required for superconductivity. There are several families of cuprate superconductors and they can be categorized by the elements they contain and the number of adjacent copper-oxide layers in each superconducting block. For example, YBCO and BSCCO can alternatively be referred to as "Y123" and Bi2201/Bi2212/Bi2223 depending on the number of layers in each superconducting block (n). The superconducting transition temperature has been found to peak at an optimal doping value (p=0.16) and an optimal number of layers in each superconducting block, typically n=3.
Possible mechanisms for superconductivity in the cuprates continue to be the subject of considerable debate and further research. Certain aspects common to all materials have been identified. Similarities between the
Similarities and differences in the properties of hole-doped and electron doped cuprates:
- Presence of a pseudogap phase up to at least optimal doping.
- Different trends in the Uemura plot relating transition temperature to the superfluid density. The inverse square of the London penetration depth appears to be proportional to the critical temperature for a large number of underdoped cuprate superconductors, but the constant of proportionality is different for hole- and electron-doped cuprates. The linear trend implies that the physics of these materials is strongly two-dimensional.
- Universal hourglass-shaped feature in the spin excitations of cuprates measured using inelastic neutron diffraction.
- Nernst effect evident in both the superconducting and pseudogap phases.
The electronic structure of superconducting cuprates is highly anisotropic (see the crystal structure of
Iron-based
Iron-based superconductors contain layers of iron and a pnictogen – such as arsenic or phosphorus – or a chalcogen. This is currently the family with the second highest critical temperature, behind the cuprates. Interest in their superconducting properties began in 2006 with the discovery of superconductivity in LaFePO at 4 K (−269.15 °C)[39] and gained much greater attention in 2008 after the analogous material LaFeAs(O,F)[40] was found to superconduct at up to 43 K (−230.2 °C) under pressure.[41] The highest critical temperatures in the iron-based superconductor family exist in thin films of FeSe,[42][43][44] where a critical temperature in excess of 100 K (−173 °C) was reported in 2014.[45]
Since the original discoveries several families of iron-based superconductors have emerged:
- LnFeAs(O,F) or LnFeAsO1−x (Ln=lanthanide) with Tc up to 56 K (−217.2 °C), referred to as 1111 materials.[9] A fluoride variant of these materials was subsequently found with similar Tc values.[46]
- (Ba,K)Fe2As2 and related materials with pairs of iron-arsenide layers, referred to as 122 compounds. Tc values range up to 38 K (−235.2 °C).[47][48] These materials also superconduct when iron is replaced with cobalt.
- LiFeAs and NaFeAs with Tc up to around 20 K (−253.2 °C). These materials superconduct close to stoichiometric composition and are referred to as 111 compounds.[49][50][51]
- FeSe with small off-stoichiometry or tellurium doping.[52]
Most undoped iron-based superconductors show a tetragonal-orthorhombic structural phase transition followed at lower temperature by magnetic ordering, similar to the cuprate superconductors.[53] However, they are poor metals rather than Mott insulators and have five bands at the Fermi surface rather than one.[38] The phase diagram emerging as the iron-arsenide layers are doped is remarkably similar, with the superconducting phase close to or overlapping the magnetic phase. Strong evidence that the Tc value varies with the As–Fe–As bond angles has already emerged and shows that the optimal Tc value is obtained with undistorted FeAs4 tetrahedra.[54] The symmetry of the pairing wavefunction is still widely debated, but an extended s-wave scenario is currently favoured.
Magnesium diboride
Magnesium diboride is occasionally referred to as a high-temperature superconductor[55] because its Tc value of 39 K (−234.2 °C) is above that historically expected for BCS superconductors. However, it is more generally regarded as the highest Tc conventional superconductor, the increased Tc resulting from two separate bands being present at the Fermi level.
Carbon-based
In 1991 Hebard et al. discovered
In 2008 Ganin et al. demonstrated superconductivity at temperatures of up to 38 K (−235.2 °C) for Cs3C60.[57]
P-doped Graphane was proposed in 2010 to be capable of sustaining high-temperature superconductivity.[58]
On 31st of December 2023 "Global Room-Temperature Superconductivity in Graphite" was published in the journal "Advanced Quantum Technologies" claiming to demonstrate superconductivity at room temperature and ambient pressure in Highly oriented pyrolytic graphite with dense arrays of nearly parallel line defects.[59]
Nickelates
In 1999, Anisimov et al. conjectured superconductivity in nickelates, proposing nickel oxides as direct analogs to the cuprate superconductors.[60] Superconductivity in an infinite-layer nickelate, Nd0.8Sr0.2NiO2, was reported at the end of 2019 with a superconducting transition temperature between 9 and 15 K (−264.15 and −258.15 °C).[61][62] This superconducting phase is observed in oxygen-reduced thin films created by the pulsed laser deposition of Nd0.8Sr0.2NiO3 onto SrTiO3 substrates that is then reduced to Nd0.8Sr0.2NiO2 via annealing the thin films at 533–553 K (260–280 °C) in the presence of CaH2.[63] The superconducting phase is only observed in the oxygen reduced film and is not seen in oxygen reduced bulk material of the same stoichiometry, suggesting that the strain induced by the oxygen reduction of the Nd0.8Sr0.2NiO2 thin film changes the phase space to allow for superconductivity.[64] Of important is further to extract access hydrogen from the reduction with CaH2, otherwise topotactic hydrogen may prevent superconductivity. [65]
Cuprates
The structure of cuprates which are superconductors are often closely related to perovskite structure, and the structure of these compounds has been described as a distorted, oxygen deficient multi-layered perovskite structure. One of the properties of the crystal structure of oxide superconductors is an alternating multi-layer of CuO2 planes with superconductivity taking place between these layers. The more layers of CuO2, the higher Tc. This structure causes a large anisotropy in normal conducting and superconducting properties, since electrical currents are carried by holes induced in the oxygen sites of the CuO2 sheets. The electrical conduction is highly anisotropic, with a much higher conductivity parallel to the CuO2 plane than in the perpendicular direction. Generally, critical temperatures depend on the chemical compositions, cations substitutions and oxygen content. They can be classified as superstripes; i.e., particular realizations of superlattices at atomic limit made of superconducting atomic layers, wires, dots separated by spacer layers, that gives multiband and multigap superconductivity.
Yttrium–barium cuprate
An yttrium–barium cuprate, YBa2Cu3O7−x (or Y123), was the first superconductor found above liquid nitrogen boiling point. There are two atoms of Barium for each atom of Yttrium. The proportions of the three different metals in the YBa2Cu3O7 superconductor are in the mole ratio of 1 to 2 to 3 for yttrium to barium to copper, respectively: this particular superconductor has also often been referred to as the 123 superconductor.
The unit cell of YBa2Cu3O7 consists of three perovskite unit cells, which is pseudocubic, nearly
Other cuprates
The preparation of other cuprates is more difficult than the YBCO preparation. They also have a different crystal structure: they are
There are three main classes of superconducting cuprates: bismuth-based, thallium-based and mercury-based.
The second cuprate by practical importance is currently
creates some chemical issues. It has three superconducting phases forming a homologous series as Bi2Sr2Can−1CunO4+2n+x (n=1, 2 and 3). These three phases are Bi-2201, Bi-2212 and Bi-2223, having transition temperatures of 20 K (−253.2 °C), 85 K (−188.2 °C) and 110 K (−163 °C), respectively, where the numbering system represent number of atoms for Bi Sr, Ca and Cu respectively.[69] The two phases have a tetragonal structure which consists of two sheared crystallographic unit cells. The unit cell of these phases has double Bi–O planes which are stacked in a way that the Bi atom of one plane sits below the oxygen atom of the next consecutive plane. The Ca atom forms a layer within the interior of the CuO2 layers in both Bi-2212 and Bi-2223; there is no Ca layer in the Bi-2201 phase. The three phases differ with each other in the number of cuprate planes; Bi-2201, Bi-2212 and Bi-2223 phases have one, two and three CuO2 planes, respectively. The c axis lattice constants of these phases increases with the number of cuprate planes (see table below). The coordination of the Cu atom is different in the three phases. The Cu atom forms an octahedral coordination with respect to oxygen atoms in the 2201 phase, whereas in 2212, the Cu atom is surrounded by five oxygen atoms in a pyramidal arrangement. In the 2223 structure, Cu has two coordinations with respect to oxygen: one Cu atom is bonded with four oxygen atoms in square planar configuration and another Cu atom is coordinated with five oxygen atoms in a pyramidal arrangement.[70]Cuprate of Tl–Ba–Ca: The first series of the Tl-based superconductor containing one Tl–O layer has the general formula TlBa2Can−1CunO2n+3,[71] whereas the second series containing two Tl–O layers has a formula of Tl2Ba2Can−1CunO2n+4 with n =1, 2 and 3. In the structure of Tl2Ba2CuO6 (Tl-2201), there is one CuO2 layer with the stacking sequence (Tl–O) (Tl–O) (Ba–O) (Cu–O) (Ba–O) (Tl–O) (Tl–O). In Tl2Ba2CaCu2O8 (Tl-2212), there are two Cu–O layers with a Ca layer in between. Similar to the Tl2Ba2CuO6 structure, Tl–O layers are present outside the Ba–O layers. In Tl2Ba2Ca2Cu3O10 (Tl-2223), there are three CuO2 layers enclosing Ca layers between each of these. In Tl-based superconductors, Tc is found to increase with the increase in CuO2 layers. However, the value of Tc decreases after four CuO2 layers in TlBa2Can−1CunO2n+3, and in the Tl2Ba2Can−1CunO2n+4 compound, it decreases after three CuO2 layers.[72]
Cuprate of Hg–Ba–Ca The crystal structure of HgBa2CuO4 (Hg-1201),[73] HgBa2CaCu2O6 (Hg-1212) and HgBa2Ca2Cu3O8 (Hg-1223) is similar to that of Tl-1201, Tl-1212 and Tl-1223, with Hg in place of Tl. It is noteworthy that the Tc of the Hg compound (Hg-1201) containing one CuO2 layer is much larger as compared to the one-CuO2-layer compound of thallium (Tl-1201). In the Hg-based superconductor, Tc is also found to increase as the CuO2 layer increases. For Hg-1201, Hg-1212 and Hg-1223, the values of Tc are 94, 128, and the record value at ambient pressure 134 K (−139 °C),[74] respectively, as shown in table below. The observation that the Tc of Hg-1223 increases to 153 K (−120 °C) under high pressure indicates that the Tc of this compound is very sensitive to the structure of the compound.[75]
Name | Formula | Temperature (K) |
Number of planes of CuO2 in unit cell |
Crystal structure |
---|---|---|---|---|
Y-123 | YBa2Cu3O7 | 92 | 2 | Orthorhombic
|
Bi-2201 | Bi2Sr2CuO6 | 20 | 1 | Tetragonal
|
Bi-2212 | Bi2Sr2CaCu2O8 | 85 | 2 | Tetragonal |
Bi-2223 | Bi2Sr2Ca2Cu3O10 | 110 | 3 | Tetragonal |
Tl-2201 | Tl2Ba2CuO6 | 80 | 1 | Tetragonal |
Tl-2212 | Tl2Ba2CaCu2O8 | 108 | 2 | Tetragonal |
Tl-2223 | Tl2Ba2Ca2Cu3O10 | 125 | 3 | Tetragonal |
Tl-1234 | TlBa2Ca3Cu4O11 | 122 | 4 | Tetragonal |
Hg-1201 | HgBa2CuO4 | 94 | 1 | Tetragonal |
Hg-1212 | HgBa2CaCu2O6 | 128 | 2 | Tetragonal |
Hg-1223 | HgBa2Ca2Cu3O8 | 134 | 3 | Tetragonal |
Preparation and manufacturing
The simplest method for preparing ceramic superconductors is a solid-state thermochemical reaction involving mixing, calcination and sintering. The appropriate amounts of precursor powders, usually oxides and carbonates, are mixed thoroughly using a
The preparation of Bi-, Tl- and Hg-based high-Tc superconductors is more difficult than the YBCO preparation. Problems in these superconductors arise because of the existence of three or more phases having a similar layered structure. Thus, syntactic intergrowth and defects such as stacking faults occur during synthesis and it becomes difficult to isolate a single superconducting phase. For Bi–Sr–Ca–Cu–O, it is relatively simple to prepare the Bi-2212 (Tc ≈ 85 K) phase, whereas it is very difficult to prepare a single phase of Bi-2223 (Tc ≈ 110 K). The Bi-2212 phase appears only after few hours of sintering at 1,130–1,140 K (860–870 °C), but the larger fraction of the Bi-2223 phase is formed after a long reaction time of more than a week at 1,140 K (870 °C).[70] Although the substitution of Pb in the Bi–Sr–Ca–Cu–O compound has been found to promote the growth of the high-Tc phase,[76] a long sintering time is still required.
Ongoing research
The question of how superconductivity arises in high-temperature superconductors is one of the major unsolved problems of theoretical condensed matter physics. The mechanism that causes the electrons in these crystals to form pairs is not known. Despite intensive research and many promising leads, an explanation has so far eluded scientists. One reason for this is that the materials in question are generally very complex, multi-layered crystals (for example, BSCCO), making theoretical modelling difficult.
Improving the quality and variety of samples also gives rise to considerable research, both with the aim of improved characterisation of the physical properties of existing compounds, and synthesizing new materials, often with the hope of increasing Tc. Technological research focuses on making HTS materials in sufficient quantities to make their use economically viable [77] as well as in optimizing their properties in relation to applications.[78] Metallic hydrogen has been proposed as a room-temperature superconductor, some experimental observations have detected the occurrence of the Meissner effect.[79][80] LK-99, copper-doped lead-apatite, has also been proposed as a room-temperature superconductor.
Theoretical models
There have been two representative theories for high-temperature or
This summary makes an
D symmetry in YBCO
An experiment based on flux quantization of a three-grain ring of
Spin-fluctuation mechanism
Despite all these years, the mechanism of high-Tc superconductivity is still highly controversial, mostly due to the lack of exact theoretical computations on such strongly interacting electron systems. However, most rigorous theoretical calculations, including phenomenological and diagrammatic approaches, converge on magnetic fluctuations as the pairing mechanism for these systems. The qualitative explanation is as follows:
In a superconductor, the flow of electrons cannot be resolved into individual electrons, but instead consists of many pairs of bound electrons, called Cooper pairs. In conventional superconductors, these pairs are formed when an electron moving through the material distorts the surrounding crystal lattice, which in turn attracts another electron and forms a bound pair. This is sometimes called the "water bed" effect. Each Cooper pair requires a certain minimum energy to be displaced, and if the thermal fluctuations in the crystal lattice are smaller than this energy the pair can flow without dissipating energy. This ability of the electrons to flow without resistance leads to superconductivity.
In a high-Tc superconductor, the mechanism is extremely similar to a conventional superconductor, except, in this case, phonons virtually play no role and their role is replaced by spin-density waves. Just as all known conventional superconductors are strong phonon systems, all known high-Tc superconductors are strong spin-density wave systems, within close vicinity of a magnetic transition to, for example, an antiferromagnet. When an electron moves in a high-Tc superconductor, its spin creates a spin-density wave around it. This spin-density wave in turn causes a nearby electron to fall into the spin depression created by the first electron (water-bed effect again). Hence, again, a Cooper pair is formed. When the system temperature is lowered, more spin density waves and Cooper pairs are created, eventually leading to superconductivity. Note that in high-Tc systems, as these systems are magnetic systems due to the Coulomb interaction, there is a strong Coulomb repulsion between electrons. This Coulomb repulsion prevents pairing of the Cooper pairs on the same lattice site. The pairing of the electrons occur at near-neighbor lattice sites as a result. This is the so-called d-wave pairing, where the pairing state has a node (zero) at the origin.
Examples
Examples of high-Tc cuprate superconductors include
Transition temperature | Item | Material type |
---|---|---|
195 K (−78 °C) | Dry ice (Carbon dioxide) – sublimation | Coolant |
184 K (−89 °C) | Lowest temperature recorded on Earth | Coolant |
110 K (−163 °C) | BSCCO
|
Cuprate superconductors |
93 K (−180.2 °C) | YBCO
| |
77 K (−196.2 °C) | Nitrogen – Boiling | Coolant |
55 K (−218.2 °C) | SmFeAs(O,F) | Iron-based superconductors |
41 K (−232.2 °C) | CeFeAs(O,F) | |
26 K (−247.2 °C) | LaFeAs(O,F) | |
18 K (−255.2 °C) | Nb3Sn
|
Metallic low-temperature superconductors |
3K (−270 °C) | Helium – boiling | Coolant |
3 K (−270.15 °C) | Hg (mercury: the first discovered superconductor) | Metallic low-temperature superconductors |
See also
- Flux pumping – Process to magnetize superconductors
- Macroscopic quantum phenomena – Macroscopic processes showing quantum behavior
- Mixed conduction– Mixed ion-electron conductor
- SQUID – Type of magnetometer
- Superconducting wire – Wires exhibiting zero resistance
- Superconductor classification – Different types of superconductors
- Superstripes – Broken symmetry phase favoring onset of superconducting or superfluid order
- Technological applications of superconductivity
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External links
- "Video of a magnet floating on a HTSC". YouTube. Archived from the original on 11 December 2021.
- "High-Temperature Superconductor Technologies". Archived from the original on 25 March 2008.
- High-Temperature Superconductivity in Cuprates. Springer. 2002. ISBN 1-4020-0810-4.
- Choi, Charles Q. (1 June 2008). "New LaOFeAs HTS". Scientific American. Retrieved 2 November 2022.
- Kordyuk, A. A. (2015). "Pseudogap from ARPES experiment: Three gaps in cuprates and topological superconductivity (Review Article)". Low Temperature Physics (Review). 41 (5): 319–341. S2CID 56392827.
- Service, Robert F. "Thanks to a bit of diamond smashing, practical room-temperature superconductivity could be close to reality". Science. AAAS.