Superconductivity
One of the most significant properties of solids is that certain metals and alloys exhibit almost zero resistivity when cooled to a sufficiently low temperature. This phenomenon is known as superconductivity.
H K Onnes (1911) observed that as purified mercury
is cooled, its resistivity vanishes abruptly at 4.2K. Onnes recognized this as
a new phenomenon and termed it superconductivity.
The temperature at which the substance loses its
resistivity and transforms into the superconducting state is the critical
temperature (Tc).
- Superconducting
transition is reversible.
- The
substances show different physical states and properties below and above
the transition temperature.
- Magnetic
behavior changes in the superconducting state
Meissner effect:
If we keep a specimen in a magnetic field at room
temperature, the magnetic flux lines penetrate the substance (Figure 1). If we
reduce the temperature to T< Tc, the flux lines will not penetrate (expelled
from the specimen). This phenomenon is known as the Meissner effect.
The magnetic susceptibility of a superconductor is
-1. That means the superconductor is getting magnetized in a direction opposite
to the applied magnetic field and behaves as a diamagnet. The superconductor
behaves like this only up to a strength for the applied magnetic field. If we
increase the magnetic field by keeping T<Tc
at a particular magnetic field, the specimen
becomes normal. This field is the critical magnetic field. Such superconductors
are known as type 1 superconductors.
In type 2 superconductors, the transition from a
superconducting state to a normal state is gradual. Different features of these
two types are given below (Figure 2)
(a) Type I superconductor (b) Type II superconductor
|
No. |
Type I |
Type II |
|
1 |
The
transformation from a superconducting state to a normal state is sudden. |
Transformation is
gradual. |
|
2 |
One critical
magnetic field |
More than one
critical magnetic field |
|
3 |
The highest known
value of the critical field is 0.1 Tesla. |
The highest value
is 0.3 Tesla. |
|
4 |
Exhibit complete
Meissner effect. |
Do not exhibit the
Meissner effect completely. |
|
5 |
Soft |
Hard |
|
6 |
Tolerate
impurities without affecting superconductivity. |
Do not tolerate
impurities. |
|
7 |
Current flow only
through the surface. |
Current flow
through the interior |
|
Examples |
Tin, Aluminum, Lead
|
Niobium, Boron,
Silicon |
The critical field decreases
as the temperature rises from 0k to T=Tc (Figure 3). That means the value of
the magnetic field is maximum at 0K and vanishes at T=Tc.
Classification
There are many criteria for classifying superconductors. The most common are:
Response to a magnetic field
- A superconductor Type I, meaning it has a single critical field.
- Above the critical field, all superconductivity is loose, and below which, the complete expulsion of the magnetic field from the superconductor
- A superconductor Type II, meaning it has two crucial fields.
- The material allows partial penetration of the magnetic field lines. [4] These points are called vortices. [5]
- A superconductor type 1.5, meaning multicomponent superconductors.
- Possibility to have a combination of the two behaviors. [6]
By operation
By critical temperature
- A superconductor is high-temperature if it reaches a superconducting state above a temperature of 30 K (−243.15 °C) [8] as in the initial discovery by Georg Bednorz and K. Alex Müller. [3]
- Low-temperature superconductors refer to materials with a critical temperature below 30 K and are cooled mainly by liquid helium (Tc > 4.2 K).
By material
High-temperature superconductivity
Until 1986, physicists had believed that BCS theory forbade superconductivity at temperatures above about 30 K. In that year, Bednorz and Müller discovered superconductivity in lanthanum barium copper oxide (LBCO), a lanthanum-based cuprate perovskite material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987). [20] Then, the invention of yttrium (i.e., making YBCO) raised the critical temperature above 90 K.[21]
This temperature jump is of particular engineering significance since it allows liquid nitrogen as a refrigerant, replacing liquid helium. [21] Liquid nitrogen is relatively cheap, even on-site. The higher temperatures help to avoid problems that arise at liquid helium temperatures, such as plugs of frozen air that can block cryogenic lines and cause unanticipated and potentially hazardous pressure buildup. [22][23]
The discovery of many other cuprate superconductors happened, and the theory of superconductivity in these materials is one of the outstanding challenges of theoretical condensed matter physics. [25][24]
Two hypotheses are there– the resonating-valence-bond theory and spin fluctuation, that support the research community. [26] The second hypothesis proposed that electron pairing in high-temperature superconductors. [27][28]
In 2008, holographic superconductivity, which uses holographic duality or AdS/CFT correspondence theory, was proposed by Gubser, Hartnoll, Herzog, and Horowitz as a possible explanation of high-temperature superconductivity in certain materials. [29]
From about 1993, the highest-temperature superconductor known as a ceramic material consisting of mercury, barium, calcium, copper, and oxygen (HgBa2Ca2Cu3O8+δ) with Tc = 133–138 K.[30][31]
An iron-based family of high-temperature superconductors was another discovery in February 2008. [32][33] Hideo Hosono of the Tokyo Institute of Technology and his colleagues found Lanthanum oxygen fluorine iron arsenide (LaO1−xFxFeAs), an oxypnictide that superconducts below 26 K. Replacing the lanthanum in LaO1−offers with samarium leads to superconductors that work at 55 K.[34]
In 2014 and 2015, hydrogen sulfide (H
2S) at extremely high pressures (around 150 gigapascals) was first predicted and then confirmed to be a high-temperature superconductor with a transition temperature of 80 K.[35][65][66] Additionally, in 2019, it was discovered that lanthanum hydride (LaH
10) becomes a superconductor at 250 K under a pressure of 170 gigapascals. [36][37]
In 2018, a research team from the Department of Physics, Massachusetts Institute of Technology, discovered superconductivity in bilayer graphene with one layer twisted at an angle of approximately 1.1 degrees with cooling and applying a small electric charge. Even if they did not do the experiments in a high-temperature environment, the correlation of the results is less to classical but high-temperature superconductors, given without introducing foreign atoms. [38] The superconductivity effect came out because of the electrons twisting into a vortex between the graphene layers, called skyrmions. These act as a single particle and can pair up across the graphene's layers, leading to the conditions required for superconductivity. [39]
- The discovery of a superconductor with a transition temperature above 77 K (boiling point of liquid nitrogen) was a remarkable development.
- Another discovery in 2006 was the discovery of Mercury Thallium Barium Calcium Copper Oxide with Tc, 138 K.
- High Tc superconductors are type II superconductors.
Applications:
Superconductors are promising materials for devising fundamental circuit elements of electronic, spintronic, and quantum technologies. One example is a superconducting diode, in which supercurrent flows along one direction only, that promises dissipationless superconducting and semiconducting-superconducting hybrid technologies. [11]
- Superconducting magnets are some of the most powerful electromagnets known.
- In MRI/NMR machines, mass spectrometers, beam-steering magnets used in particle accelerators, and plasma confining magnets in some tokamaks, etc., we use superconductors.
- In the pigment industries, use it for magnetic separation, for extracting weakly magnetic particles from a background of fewer or non-magnetic particles.
- In large wind turbines, to overcome the restrictions imposed by high electrical currents.
An industrial grade 3.6 megawatt superconducting windmill generator has been tested successfully in Denmark. [12]
In the 1950s and 1960s, experimental digital computers with superconductors and cryotron switches. [13] Recently, scientists applied superconductors to make digital circuits based on rapid single flux quantum technology and RF and microwave filters for mobile phone base stations.
The most spectacular application of superconducting magnets is:
- Maglev trains, levitated trains for a rapid transit system.
- Small-scale superconducting devices are with the principle of Josephson tunneling.
- The most promising application of the Josephson effect is in the superconducting quantum interference device (SQUID). The memory cells are made of SQUID and are faster and free of energy dissipation.
- For making sensitive magnetometers, we can use this material.
- These magnetometers measure weak magnetic fields.
- Using these magnetometers, we can measure magnetic signals produced by the human heart and brain.
Other uses are:
- To build Josephson junctions, which are the building blocks of SQUIDs (superconducting quantum interference devices), the most sensitive magnetometers known.
- To build scanning SQUID microscopes and magnetoencephalography.
- Superconducting photon detectors[14] can be realized in several device configurations.
- To build thermometers in cryogenic micro-calorimeter photon detectors and ultrasensitive bolometers.
- Superconducting nanowire single-photon detectors offer high-speed, low-noise single-photon detection and have been employed widely in advanced photon-counting applications. [15]
Other early markets are arising where the relative efficiency, size, and weight advantages of devices based on high-temperature superconductivity outweigh the additional costs involved. For example, in wind turbines, lower weight and volume of superconducting generators could lead to savings in construction and tower costs, offsetting the higher costs for the generator and lowering the total levelized cost of electricity (LCOE). [16]
Promising future applications:
- High-performance smart grids.
- Electric power transmission.
- Magnetic levitation devices, fault current limiters, enhancing spintronic devices with superconducting materials,[17] and superconducting magnetic refrigeration, etc.,
- However, superconductivity is sensitive to moving magnetic fields, so applications that use alternating current (e.g., transformers) will be developed than those that rely upon direct current.
Compared to traditional power lines, superconducting transmission lines are more efficient and require only a fraction of the space, which leads to better environmental performance and improved public acceptance. [18] Another attractive industrial aspect is the ability for high power transmission at lower voltages. [19] Advancements in the efficiency of cooling systems and cheap coolants such as liquid nitrogen helped to
decrease in the cooling costs needed for superconductivity.
Recent developments:
- The material with the highest accepted superconducting temperature is highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K [1,2].
In 2020, a room-temperature superconductor (critical temperature 288 K) developed from hydrogen, carbon, and sulfur under pressures of around 270 gigapascals (a paper in Nature). [40][41]
On 31 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. [43]
References:
1
Somayazulu et al., Phy. Rev., Lett 122 (2).
2
Drozdov et al., Nature, 569 (7757), 528-531.
3 Bednorz, J. G. & Müller, K. A. (1986). "Possible high Tc superconductivity in the 4 Ba−La−Cu−O system". Z. Phys. B. 64 (1): 189–193. Bibcode:1986ZPhyB..64..189B. doi:10.1007/BF01303701. S2CID 118314311
.
4 ^ "Superconductivity | CERN". home.cern. Retrieved 2020-10-29.5^ Orthacker, Angelina. "Superconductivity" (PDF). Technical University of Graz.
6^ "Type-1.5 superconductor shows its stripes". Physics World. 2009-02-17. Retrieved 2020-10-29.
7^ Gibney, Elizabeth (5 March 2018). "Surprise graphene discovery could unlock secrets of superconductivity". News. Nature. 555 (7695): 151–152. Bibcode:2018Natur.555..151G. doi:10.1038/d41586-018-02773-w. PMID 29517044.
Superconductors come broadly in two types: conventional, in which the activity can be explained by the mainstream theory of superconductivity, and unconventional, where it can't.
9^ Flores-Livas, José A.; et al. (29 April 2020). "A perspective on conventional high-temperature superconductors at high pressure: Methods and materials". Physics Reports. 856: 1–78. arXiv:1905.06693. Bibcode:2020PhR...856....1F. doi:10.1016/j.physrep.2020.02.003. S2CID 155100283
10^ Hirsch, J. E.; Maple, M. B.; Marsiglio, F. (2015-07-15). "Superconducting materials classes: Introduction and overview". Physica C: Superconductivity and Its Applications. Superconducting Materials: Conventional, Unconventional, and Undetermined. 514: 1–8. arXiv:1504.03318. Bibcode:2015PhyC..514....1H. doi:10.1016/j.physc.2015.03.002. ISSN 0921-4534. S2CID 12895850
11 ^ "Classification of Superconductors"(PDF)., CERN.
12 ^ Design and in-field testing of the world's first ReBCO rotor for a 3.6 MW wind generator" by Anne Bergen, Rasmus Andersen, Markus Bauer, Hermann Boy, Marcel ter Brake, Patrick Brutsaert, Carsten Bührer, Marc Dhallé, Jesper Hansen and Herman ten Kate, 25 October 2019, Superconductor Science and Technology.
13^ Brock, David C. (2014-03-19). "Dudley Buck's Forgotten Cryotron Computer". Institute of Electrical and Electronics Engineers. Retrieved 2021-03-30.
15^ Natarajan, C. M. (April 2012). "Superconducting nanowire single-photon detectors: physics and applications". Superconductor Science and Technology. 25 (6): 063001. arXiv:1204.5560. Bibcode:2012SuScT..25f3001N. doi:10.1088/0953-2048/25/6/063001. S2CID 4893642 – via IOP Publishing.
16^ Islam; et al. (2014). "A review of offshore wind turbine nacelle: Technical challenges, and research and developmental trends". Renewable and Sustainable Energy Reviews. 33: 161–176. doi:10.1016/j.rser.2014.01.085. hdl:10453/33256.
17^ Linder, Jacob; Robinson, Jason W. A. (2 April 2015). "Superconducting spintronics". Nature Physics. 11 (4): 307–315. arXiv:1510.00713. Bibcode:2015NatPh..11..307L. doi:10.1038/nphys3242. S2CID 31028550
18^ Thomas; et al. (2016). "Superconducting transmission lines – Sustainable electric energy transfer with higher public acceptance?" (PDF). Renewable and Sustainable Energy Reviews. 55: 59–72. doi:10.1016/j.rser.2015.10.041.
19^ Ren, Li; et al. (2009). "Technical and Economical Assessment of HTS Cables". IEEE Transactions on Applied Superconductivity. 19 (3): 1774–1777. doi:10.1109/TASC.2009.2019058. S2CID 46117301
22 ^ "Introduction to Liquid Helium". Cryogenics and Fluid Branch. Goddard Space Flight Center, NASA.
23 ^ "Section 4.1 'Air plug in the fill line'". Superconducting Rock Magnetometer Cryogenic System Manual. 2G Enterprises. Archived from the original on May 6, 2009. Retrieved 9 October 2012.
24^ Abrikosov, Alexei A. (8 December 2003). "type II Superconductors and the Vortex Lattice". Nobel Lecture.
25^ Gingras, Olivier (Sep 2021). La supraconductivité non-conventionnelle du ruthénate de strontium: corrélations électroniques et couplage spin-orbite (in French). PhD thesis.
26^ Mann, Adam (July 20, 2011). "High-temperature superconductivity at 25: Still in suspense". Nature. 475 (7356): 280–2. Bibcode:2011Natur.475..280M. doi:10.1038/475280a. PMID 21776057. S2CID 205066154
27^ Pines, D. (2002), "The Spin Fluctuation Model for High Temperature Superconductivity: Progress and Prospects", The Gap Symmetry and Fluctuations in High-Tc Superconductors, NATO Science Series: B, vol. 371, New York: Kluwer Academic, pp. 111–142, doi:10.1007/0-306-47081-0_7, ISBN 978-0-306-45934-4
28 ^ Monthoux, P.; Balatsky, A. V. & Pines, D. (1991). "Toward a theory of high-temperature superconductivity in the antiferromagnetically correlated cuprate oxides". Physical Review Letters. 67 (24): 3448–3451. Bibcode:1991PhRvL..67.3448M. doi:10.1103/PhysRevLett.67.3448. PMID 10044736
29 ^ Jan Zaanen, Yan Liu, Ya Sun K.Schalm (2015). Holographic Duality in Condensed Matter Physics. Cambridge University Press, Cambridge.
30 ^ Schilling, A.; et al. (1993). "Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system". Nature. 363 (6424): 56–58. Bibcode:1993Natur.363...56S. doi:10.1038/363056a0. S2CID 4328716
31 ^ Dai, P.; Chakoumakos, B. C.; Sun, G. F.; Wong, K. W.; et al. (1995). "Synthesis and neutron powder diffraction study of the superconductor HgBa2Ca2Cu3O8+δ by Tl substitution". Physica C. 243 (3–4): 201–206. Bibcode:1995PhyC..243..201D. doi:10.1016/0921-4534(94)02461-8
32 ^ Takahashi, Hiroki; Igawa, Kazumi; Arii, Kazunobu; Kamihara, Yoichi; et al. (2008). "Superconductivity at 43 K in an iron-based layered compound LaO1−xFxFeAs". Nature. 453 (7193): 376–378. Bibcode:2008Natur.453..376T. doi:10.1038/nature06972. PMID 18432191. S2CID 498756
33 ^ Cho, Adrian (2014-10-30). "Second Family of High-Temperature Superconductors Discovered". ScienceNOW Daily News.
34 ^ Ren, Zhi-An; et al. (2008). "Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1-d (Re = rare-earth metal) without fluorine doping". EPL. 83 (1): 17002. arXiv:0804.2582. Bibcode:2008EL.....8317002R. doi:10.1209/0295-5075/83/17002. S2CID 96240327
35 ^ Li, Yinwei; Hao, Jian; Liu, Hanyu; Li, Yanling; Ma, Yanming (2014-05-07). "The metallization and superconductivity of dense hydrogen sulfide". The Journal of Chemical Physics. 140 (17): 174712. arXiv:1402.2721. Bibcode:2014JChPh.140q4712L. doi:10.1063/1.4874158. ISSN 0021-9606. PMID 24811660. S2CID 15633660
37 ^ Jump up to:a b Wood, Charlie (14 October 2020). "Room-Temperature Superconductivity Achieved for the First Time". Quanta Magazine. Retrieved 2020-10-29.38
40^ Snider, Elliot; Dasenbrock-Gammon, Nathan; McBride, Raymond; Debessai, Mathew; Vindana, Hiranya; Vencatasamy, Kevin; Lawler, Keith V.; Salamat, Ashkan; Dias, Ranga P. (26 September 2022). "Retraction Note: Room-temperature superconductivity in a carbonaceous sulfur hydride". Nature. 610 (7933): 804. Bibcode:2022Natur.610..804S. doi:10.1038/s41586-022-05294-9. PMID 36163290. S2CID 252544156
40 ^ Kopelevich, Yakov; Torres, José; Da Silva, Robson; Oliveira, Felipe; Diamantini, Maria Cristina; Trugenberger, Carlo; Vinokur, Valerii (2024). "Global Room-Temperature Superconductivity in Graphite". Advanced Quantum Technologies. 7 (2). arXiv:2208.00854. doi:10.1002/qute.202300230
43^ Brock, David C. (2014-03-19). "Dudley Buck's Forgotten Cryotron Computer". Institute of Electrical and Electronics Engineers. Retrieved 2021-03-30.
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