BCS theory

BCS theory successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. BCS theory views superconductivity as a macroscopic quantum mechanical effect. It proposes that electrons with opposite spin can become paired, forming Cooper pairs.

Related Topics:
Conventional superconductivity - Metal - Temperature - Electricity - Resistance - Superconductivity - Quantum mechanical - Electron - Spin

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In many superconductors, the attractive interaction between electrons (necessary for pairing) is brought about indirectly by the interaction between the electrons and the vibrating crystal lattice (the phonons). Roughly speaking the picture is the following:

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An electron moving through a conductor will cause a slight increase in concentration of positive charges in the lattice around it; this increase in turn can attract another electron. In effect, the two electrons are then held together with a certain binding energy. If this binding energy is higher than the energy provided by kicks from oscillating atoms in the conductor (which is true at low temperatures), then the electron pair will stick together and resist all kicks, thus not experiencing resistance.

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BCS theory was developed in 1957 by John Bardeen, Leon Cooper, and Robert Schrieffer, who received the Nobel Prize for Physics in 1972 as a result.

Related Topics:
John Bardeen - Leon Cooper - Robert Schrieffer - Nobel Prize

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In 1986, "high-temperature superconductivity" was discovered (i.e. superconductivity at temperatures

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considerably above the previous limit of about 30 K; up

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to about 130 K).

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It is believed that at these temperatures other effects are at play; these effects are not yet fully understood.

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(It is possible that these unknown effects also control superconductivity even at low temperatures for some

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materials)

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An excellent introduction to BCS theory and related areas of condensed matter physics at the graduate level is Schrieffer's book, Theory of Superconductivity, ISBN 0-7382-0120-0.

Related Topics:
Condensed matter physics - Schrieffer

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