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Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases that arise from electromagnetic forces between atoms and electrons. More generally, the subject deals with condensed phases of matter: systems of many constituents with strong interactions among them. More exotic condensed phases include the superconducting phase exhibited by certain materials at extremely low cryogenic temperatures, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, the Bose–Einstein condensates found in ultracold atomic systems, and liquid crystals. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other physics theories to develop mathematical models and predict the properties of extremely large groups of atoms.
Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered, even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.
Unconventional superconductors are materials that display superconductivity which does not conform to conventional BCS theory or its extensions.
High-temperature superconductors are defined as materials with critical temperature above 77 K, the boiling point of liquid nitrogen. They are only "high-temperature" relative to previously known superconductors, which function at even colder temperatures, close to absolute zero. The "high temperatures" are still far below ambient, and therefore require cooling. The first break through of high-temperature superconductor was discovered in 1986 by IBM researchers Georg Bednorz and K. Alex Müller. Although the critical temperature is around 35.1 K, this new type of superconductor was readily modified by Ching-Wu Chu to make the first high-temperature superconductor with critical temperature 93 K. Bednorz and Müller were awarded the Nobel Prize in Physics in 1987 "for their important break-through in the discovery of superconductivity in ceramic materials". Most high-Tc materials are type-II superconductors.
A room-temperature superconductor is a hypothetical material capable of displaying superconductivity at temperatures above 0 °C, which are commonly encountered in everyday settings. As of 2023, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K (−23 °C) at 200 GPa.
A superconducting magnet is an electromagnet made from coils of superconducting wire. They must be cooled to cryogenic temperatures during operation. In its superconducting state the wire has no electrical resistance and therefore can conduct much larger electric currents than ordinary wire, creating intense magnetic fields. Superconducting magnets can produce stronger magnetic fields than all but the strongest non-superconducting electromagnets, and large superconducting magnets can be cheaper to operate because no energy is dissipated as heat in the windings. They are used in MRI instruments in hospitals, and in scientific equipment such as NMR spectrometers, mass spectrometers, fusion reactors and particle accelerators. They are also used for levitation, guidance and propulsion in a magnetic levitation (maglev) railway system being constructed in Japan.
In superconductivity, a type-II superconductor is a superconductor that exhibits an intermediate phase of mixed ordinary and superconducting properties at intermediate temperature and fields above the superconducting phases. It also features the formation of magnetic field vortices with an applied external magnetic field. This occurs above a certain critical field strength Hc1. The vortex density increases with increasing field strength. At a higher critical field Hc2, superconductivity is destroyed. Type-II superconductors do not exhibit a complete Meissner effect.
Michael Tinkham was an American physicist. He was Rumford Professor of Physics and Gordon McKay Research Professor of Applied Physics at Harvard University. He is best known for his work on superconductivity.
Cuprate superconductors are a family of high-temperature superconducting materials made of layers of copper oxides (CuO2) alternating with layers of other metal oxides, which act as charge reservoirs. At ambient pressure, cuprate superconductors are the highest temperature superconductors known. However, the mechanism by which superconductivity occurs is still not understood.
Klaus Bechgaard was a Danish scientist and chemist, noted for being one of the first scientists in the world to synthesize a number of organic charge transfer complexes and demonstrate their superconductivity, therefore the name Bechgaard salt. These salts all exhibit superconductivity at low temperatures.
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.
The 122 iron arsenide unconventional superconductors are part of a new class of iron-based superconductors. They form in the tetragonal I4/mmm, ThCr2Si2 type, crystal structure. The shorthand name "122" comes from their stoichiometry; the 122s have the chemical formula AEFe2Pn2, where AE stands for alkaline earth metal (Ca, Ba Sr or Eu) and Pn is pnictide (As, P, etc.). These materials become superconducting under pressure and also upon doping. The maximum superconducting transition temperature found to date is 38 K in the Ba0.6K0.4Fe2As2. The microscopic description of superconductivity in the 122s is yet unclear.
Distrontium ruthenate, also known as strontium ruthenate, is an oxide of strontium and ruthenium with the chemical formula Sr2RuO4. It was the first reported perovskite superconductor that did not contain copper. Strontium ruthenate is structurally very similar to the high-temperature cuprate superconductors, and in particular, is almost identical to the lanthanum doped superconductor (La, Sr)2CuO4. However, the transition temperature for the superconducting phase transition is 0.93 K (about 1.5 K for the best sample), which is much lower than the corresponding value for cuprates.
Alexander V. Balatsky is a USSR-born American physicist. He is the professor of theoretical physics at NORDITA and University of Connecticut. He served as the founding director of the Institute for Materials Science (IMS) at Los Alamos National Laboratory in 2014–2017.
Laura H. Greene is the Marie Krafft Professor of Physics at Florida State University and chief scientist at the National High Magnetic Field Laboratory. She was previously a professor of physics at the University of Illinois at Urbana-Champaign. In September 2021, she was appointed to the President's Council of Advisors on Science and Technology (PCAST).
Mohit Randeria is a US-based Indian condensed matter physicist and a professor of physics at Ohio State University. Known for his research on condensed matter theory and superconductivity, Randeria is an elected fellow of the American Physics Society. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, for his contributions to physical sciences in 2002. He was awarded the 2002 ICTP Prize of the International Center for Theoretical Physics, Trieste and the 2022 John Bardeen Prize.
Paul Michael Grant was an American/Irish physicist and science writer who was involved in discovering and elucidating the structure of Yttrium Barium Copper Oxide which was important as the first high temperature superconductor to exhibit superconductivity above the boiling point of Nitrogen. He was a co-author of IBM's US patent application covering their preparation.
Carbonaceous sulfur hydride (CSH) is a potential superconductor that was announced in October 2020 by the lab of Ranga Dias at the University of Rochester, in a Nature paper that was later retracted. It was reported to have a superconducting transition temperature of 15 °C (59 °F) at a pressure of 267 gigapascals (GPa), which would have made it the highest-temperature superconductor discovered. The paper faced criticism dut to its non-standard data analysis calling into question its conclusions, and in September 2022 it was retracted by Nature. In July 2023 a second paper by the authors was retracted from Physical Review Letters due to suspected data fabrication, and in September 2023 a third paper by the authors about N-doped lutetium hydride was retracted from Nature.
Uranium ditelluride is an inorganic compound with the formula UTe2. It was discovered to be an unconventional superconductor in 2018.
LK-99, also called PCPOSOS, is a gray–black, polycrystalline compound, identified as a copper-doped lead‒oxyapatite. A team from Korea University led by Lee Sukbae (이석배) and Kim Ji-Hoon (김지훈) began studying this material as a potential superconductor starting in 1999. In July 2023, they published preprints claiming that it acts as a room-temperature superconductor at temperatures of up to 400 K at ambient pressure.
References
- ↑ "Miassite".
- ↑ "A Superconductor Found in Nature Has Rocked the Scientific World". Popular Mechanics. 2024-03-19. Retrieved 2024-03-20.
- ↑ "Scientists reveal the first unconventional superconductor that can be found in mineral form in nature". MSN .
- ↑ "A Superconductor Found in Nature Has Rocked the Scientific World". Popular Mechanics. 2024-03-19. Retrieved 2024-03-20.