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
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 ...
Magnet Lab to Investigate Promising Superconductor
Oct 13, 2009 |
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(PhysOrg.com) -- The Applied Superconductivity Center at the National High Magnetic Field Laboratory has received $1.2 million in funding from the U.S. Department of Energy to understand and enhance a new form of superconducting ...
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 ...
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.
Superconductivity: Which one of these is not like the other?
Jul 13, 2009 |
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Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors. The insight comes from research groups that are making bold statements about the correct description ...
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 ...
Researchers discovers how strain at grain boundaries suppresses high-temperature superconductivity
Jun 17, 2009 |
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Researchers at the National Institute of Standards and Technology (NIST) have discovered that a reduction in mechanical strain at the boundaries of crystal grains can significantly improve the performance ...
Evidence of macroscopic quantum tunneling detected in nanowires
May 27, 2009 |
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A team of researchers at the University of Illinois has demonstrated that, counter to classical Newtonian mechanics, an entire collection of superconducting electrons in an ultrathin superconducting wire is ...
Researchers Explore Magnetic Properties of Iron-Based Superconductors
Apr 13, 2009 |
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(PhysOrg.com) -- Scientists at the Naval Research Laboratory have proposed theoretical models to explain the normal magnetic properties in iron-based superconductors. This research was published in the December ...
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 ...
Researchers explore magnetic properties of iron-based superconductors
Mar 16, 2009 |
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Scientists at the Naval Research Laboratory (NRL) have proposed theoretical models to explain the normal magnetic properties in iron-based superconductors. This research was published in the December 21, 2008 ...
Physicists offer new theory for iron compounds
Mar 12, 2009 |
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An international team of physicists from the United States and China this week offered a new theory to both explain and predict the complex quantum behavior of a new class of high-temperature superconductors.
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 ...
Superconductivity: the new high critical temperature superconductors
Feb 24, 2009 |
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(PhysOrg.com) -- The paper published in the Journal of the American Chemical Society (JACS) by a team led by professor Francesc Illas of the University of Barcelona's Department of Physical Chemistry and di ...
Physicists observe kink in the dispersion of f-electrons
Feb 02, 2009 |
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(PhysOrg.com) -- Los Alamos researchers in collaboration with colleagues in US and Europe report on the observation of a kink in the dispersion of f-electrons in USb2.
