Superconductive

Superconductive is an adjective relating to superconductivity, the phenomenon by which certain materials conduct electric current with zero direct-current resistance and expel magnetic fields when cooled below a characteristic critical temperature. In a superconductor, electrons form bound pairs, known as Cooper pairs, which move without scattering and thus without electrical resistance. The effect was discovered by Heike Kamerlingh Onnes in 1911 in mercury. Superconductivity occurs below a material’s Tc and within certain magnetic-field limits; above these limits, superconductivity is destroyed. Type I superconductors display a complete Meissner effect and a single critical field, while Type II superconductors tolerate higher fields by forming quantized magnetic flux vortices.

Conventional superconductivity is well described by BCS theory (1957), which explains Cooper pairing mediated by lattice vibrations (phonons). The energy gap opens at the Fermi surface, and superconductivity is accompanied by zero DC resistance and the Meissner effect. Since 1986, high-temperature or unconventional superconductors—most notably cuprates and, later, iron-based compounds—have challenged existing theory and suggested mechanisms beyond BCS. More recently, hydrogen-rich materials under extreme pressure have achieved record critical temperatures above 200 K, though these require megabar pressures and are not yet practical for widespread use.

Applications of superconductors include high-field magnets for magnetic resonance imaging (MRI) and particle accelerators, magnetic-levitation systems, and superconducting quantum interference devices (SQUIDs) for sensitive magnetometry. Ongoing research aims to discover or engineer materials with higher Tc at ambient pressure, improve fabrication, and enable scalable superconducting electronics and power transmission.