High-temperature superconductivity

Superconductivity occurring at temperatures unusually high for superconductors, often above the boiling point of liquid nitrogen. It occurs in several material families whose pairing mechanisms remain incompletely understood.

Cooper pair: A bound pair of electrons that can move coherently through a superconductor without ordinary electrical resistance. High-temperature superconductors also exhibit paired electrons, though their pairing mechanism differs from conventional cases.
Critical temperature: The temperature below which a material enters a superconducting state. It provides the defining temperature scale for comparing high-temperature superconductors.
Johannes Georg Bednorz: A German physicist who shared the 1987 Nobel Prize in Physics for discovering superconductivity in ceramic materials. His work with Müller initiated the modern high-temperature superconductivity surge.
Superconducting wire: A conductor made from superconducting material for carrying current with negligible electrical resistance below its transition temperature. Practical high-temperature materials must often be formed into long, robust current-carrying conductors.
Mechanism of high-temperature superconductivity: The unresolved physical account of how superconducting pairing arises in materials with unusually high transition temperatures. No single microscopic explanation accounts conclusively for the major high-temperature material families.
BCS theory: A theory explaining conventional superconductivity through electron pairing mediated by lattice vibrations. Its phonon-based account explains conventional superconductors but does not fully explain high transition temperatures.
Cuprate: A compound containing copper and oxygen, especially layered copper oxides studied for superconductivity. Cuprates produced the first widely recognized materials superconducting above liquid-nitrogen temperature.
Karl Alexander Müller: A Swiss physicist who shared the 1987 Nobel Prize in Physics for discovering superconductivity in ceramic materials. His collaboration with Bednorz uncovered superconductivity in a lanthanum-barium copper oxide.
Superconducting magnet: An electromagnet whose coils use superconductors to sustain large currents with little resistive loss. Higher operating temperatures could simplify cooling for powerful magnets.
Charge density wave: A periodic modulation of electronic charge density coupled to a distortion of a material’s lattice. Charge order competes or intertwines with superconductivity in several copper oxides.

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