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 superconductors
Using superconducting probes to get a picture of what it's like inside CNTs
Nov 20, 2009 |
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(PhysOrg.com) -- "Carbon nanotubes are exciting for fundamental physics, and for potential technological applications," Nadya Mason tells PhysOrg.com. "However, we are generally limited in the way that we can study them. ...
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 ...
LHC now colder than deep space
Oct 20, 2009 |
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(PhysOrg.com) -- The LHC (Large Hadron Collider) is once again colder than deep space as it is prepared for experiments to resume in late November.
For Future Superconductors, a Little Bit of Lithium May Do Hydrogen a Lot of Good
Oct 05, 2009 |
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(PhysOrg.com) -- Scientists have a long and unsuccessful history of attempting to convert hydrogen to a metal by squeezing it under incredibly high and steady pressures.
Scientists Detect 'Fingerprint' of High-Temp Superconductivity Above Transition Temperature
Aug 27, 2009 |
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(PhysOrg.com) -- A team of U.S. and Japanese scientists has shown for the first time that the spectroscopic "fingerprint" of high-temperature superconductivity remains intact well above the super chilly temperatures ...
Hydrogen-rich Material Promises Advances in Energy Transmission, Fuel Storage
Aug 20, 2009 |
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(PhysOrg.com) -- Researchers at the Stanford Institute for Materials and Energy Science, a joint institute of SLAC and Stanford University, have produced a hydrogen-rich alloy that could provide insight into ...
Research pokes holes in Hubbard model: Could help solve enigma of high-temperature superconductors
Aug 19, 2009 |
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New UBC research has literally and figuratively poked holes in single-band Hubbard physics--a model that has been used to predict and calculate the behavior of high-temperature superconductors for 20 years.
Fire Meets Ice: Superhot And Supercold Remarkably Similar In The 'Fermion' World (w/ Video)
Aug 04, 2009 |
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Trapping and cooling a microscopic clump of gas and then suddenly releasing it would normally result in the gas rapidly expanding outward in all directions, like a spherical bubble.
Magnetic Measurements Question Assumptions About High-Tc Superconductors
Aug 03, 2009 |
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(PhysOrg.com) -- Conquering one of the biggest challenges in the study of high-temperature (high-Tc) superconductors, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have grown ...
New insights, and a new angle, on high-temperature superconductivity
Jun 29, 2009 |
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(PhysOrg.com) -- A Princeton-led research team has revealed surprising information about how electron behavior influences the conduction of electricity in a class of high-temperature superconductors. An increased ...
Europium discovery: New element found to be a superconductor
May 13, 2009 |
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(PhysOrg.com) -- Of the 92 naturally occurring elements, add another to the list of those that are superconductors. James S. Schilling, Ph.D., professor of physics in Arts & Sciences at Washington University ...
Frozen helium-4 may be an unusual 'superglass'
May 01, 2009 |
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(PhysOrg.com) -- When helium is cooled to around 4 degrees above absolute zero, it turns liquid. Make it a couple of degrees cooler, and it becomes a "superfluid" that flows without resistance from its container, ...
Putting the Pressure on Iron-Based Superconductors
Mar 05, 2009 |
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(PhysOrg.com) -- Traditionally, magnetism and superconductivity don't mix. For more than 20 years, the only known superconductors that worked at so-called "high" temperatures (above 30 K, or about -406 degrees ...
Secrets behind high temperature superconductors revealed
Feb 22, 2009 |
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(PhysOrg.com) -- Scientists from Queen Mary, University of London and the University of Fribourg (Switzerland) have found evidence that magnetism is involved in the mechanism behind high temperature superconductivity.
Students demonstrate flux pinning in low gravity
Oct 27, 2009 |
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(PhysOrg.com) -- A team of Cornell researchers recently tested their work on the mysterious physical phenomenon of flux pinning aboard a near-zero gravity aircraft.
