The waltz of the LHC magnets has begun

Major endeavors are underway in the Large Hadron Collider (LHC) over the past few weeks, with the extraction of magnets from the accelerator tunnel. The LHC has a total of 1232 dipoles, magnets which bend the particles' trajectories, ...

Researcher discusses reopening the case of cold fusion

Researchers at MIT have collaborated with a team of scientists from the University of British Columbia, the University of Maryland, Lawrence Berkeley National Laboratory, and Google to conduct a multiyear investigation into ...

Strain enables new applications of 2-D materials

Superconductors' never-ending flow of electrical current could provide new options for energy storage and superefficient electrical transmission and generation, to name just a few benefits. But the signature zero electrical ...

Computing faster with quasi-particles

Majorana particles are very peculiar members of the family of elementary particles. First predicted in 1937 by the Italian physicist Ettore Majorana, these particles belong to the group of so-called fermions, a group that ...

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Superconductivity

Superconductivity 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.

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