Superconductivity
hideSuperconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect). It was discovered by Heike Kamerlingh Onnes in 1911. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It cannot be understood simply as the idealization of "perfect conductivity" in classical physics.
The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit. Even near absolute zero a real sample of copper shows a non-zero resistance. The resistance of a superconductor, despite these imperfections, drops abruptly to zero when the material is cooled below its "critical temperature". An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source.
Superconductivity occurs in a wide variety of materials, including simple elements like tin and aluminium, various metallic alloys and some heavily-doped semiconductors. Superconductivity does not occur in noble metals like gold and silver, nor in pure samples of ferromagnetic metals.
In 1986 the discovery of a family of cuprate-perovskite ceramic materials known as high-temperature superconductors, with critical temperatures in excess of 90 kelvin, spurred renewed interest and research in superconductivity for several reasons. As a topic of pure research, these materials represented a new phenomenon not explained by the current theory. In addition, because the superconducting state persists up to more manageable temperatures, past the economically-important boiling point of liquid nitrogen (77 kelvin), more commercial applications are feasible, especially if materials with even higher critical temperatures could be discovered.
See also the history of superconductivity.
For more information about Superconductivity, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with superconductivity
Room temperature superconductivity: One step closer to the Holy Grail of physics
Jul 09, 2008 |
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Scientists at the University of Cambridge have for the first time identified a key component to unravelling the mystery of room temperature superconductivity, according to a paper published in today's edition of the scientific ...
Breakthrough experiment on high-temperature superconductors
Dec 12, 2008 |
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(PhysOrg.com) -- New information about the metallic state from which high temperature superconductivity emerges, has been revealed in an innovative experiment performed at the University of Bristol.
Physical reality of string theory demonstrated
Jul 06, 2009 |
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String theory has come under fire in recent years. Promises have been made that have not been lived up to. Leiden (The Netherlands) theoretical physicists have now for the first time used string theory to describe a physical ...
Physicists shed light on key superconductivity riddle
Jul 21, 2008 |
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(PhysOrg.com) -- MIT physicists believe they have identified a mysterious state of matter that has been linked to the phenomenon of high-temperature superconductivity.
Superconductivity can induce magnetism
Sep 11, 2008 |
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When an electrical current passes through a wire it emanates heat - a principle that's found in toasters and incandescent light bulbs. Some materials, at low temperatures, violate this law and carry current without any heat ...
Magnetism and Superconductivity Observed to Exist in Harmony
Aug 28, 2008 |
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(Physorg.com) -- Physicists at Los Alamos National Laboratory, along with colleagues at institutions in Switzerland and Canada, have observed, for the first time in a single exotic phase, a situation where magnetism and superconductivity ...
Disappearing Superconductivity Reappears -- in 2-D
Dec 01, 2008 |
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(PhysOrg.com) -- Scientists studying a material that appeared to lose its ability to carry current with no resistance say new measurements reveal that the material is indeed a superconductor — but only in ...
Exotic materials using neptunium, plutonium provide insight into superconductivity
Jul 21, 2008 |
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Physicists at Rutgers and Columbia universities have gained new insight into the origins of superconductivity - a property of metals where electrical resistance vanishes - by studying exotic chemical compounds that contain ...
Scientists See New Mechanism for Superconductivity
Nov 21, 2008 |
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(PhysOrg.com) -- Los Alamos National Laboratory researchers have posited an explanation for superconductivity that may open the door to the discovery of new, unconventional forms of superconductivity.
Iron-based Materials May Unlock Superconductivity's Secrets
Nov 13, 2008 |
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(PhysOrg.com) -- Researchers at the National Institute of Standards and Technology (NIST) are decoding the mysterious mechanisms behind the high-temperature superconductors that industry hopes will find wide ...
Squashing Silane into Metal
Jan 09, 2009 |
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(PhysOrg.com) -- Squeeze it hard enough and hydrogen, the most abundant and lightest element in our Universe, strangely takes on a metallic nature. During this state, as it loses hold of its electrons, hydrogen ...
Pinning Down Superconductivity to a Single Layer
Oct 29, 2009 |
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(PhysOrg.com) -- Using precision techniques for making superconducting thin films layer-by-layer, physicists at the U.S. Department of Energy's Brookhaven National Laboratory have identified a single layer ...
Study Yields Surprising New Insight into High-Temp Superconductors
Mar 17, 2009 |
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(PhysOrg.com) -- Recently, an international group of researchers discovered that the underlying mechanism producing high-temperature superconductivity in a widely studied class of copper-oxygen-based superconductors may be ...
Scientists prove unconventional superconductivity in new iron arsenide compounds
Jan 09, 2009 |
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(PhysOrg.com) -- Scientists at U.S. Department of Energy's Argonne National Laboratory used inelastic neutron scattering to show that superconductivity in a new family of iron arsenide superconductors cannot ...
Physicists discover surprising variation in superconductors
Jan 28, 2009 |
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(PhysOrg.com) -- MIT physicists have discovered that several high-temperature superconductors display patchwork quilt-like variations at the atomic scale, a surprising finding that could help scientists understand a new class ...
