Superconductors

A superconductor is a material that exhibits zero resistance to the flow of electrical current and becomes diamagnetic (opaque to magnetic fields) when cooled to a sufficiently low temperature.

An electrical current will persist indefinitely in a ring of superconducting material; also, a magnet can be levitated (suspended in space) by the magnetic field produced by a superconducting, diamagnetic object. Because of these unique properties, superconductors have found wide applications in the generation of powerful magnetic fields, magnetometry, magnetic shielding, and other technologies. Many researchers are seeking to devise hightemperature superconductors—materials that superconduct at or above the boiling point of nitrogen (N₂), 77 K (Kelvin)—in order to carry large amounts of current without lapsing from the superconducting state. Such materials...