Discovery and two key properties
In 1911 Heike Kamerlingh Onnes at Leiden University cooled mercury to 4.2 K (−269 °C) with liquid helium he had learned to produce and saw its electrical resistance abruptly vanish, earning the 1913 Nobel Prize in Physics. In 1933 Germany's Walther Meissner and Robert Ochsenfeld found that superconductors also expel magnetic fields from their interior. The famous images of a magnet hovering over a superconductor show this Meissner effect. Zero resistance alone is not enough; a true superconductor must also show the Meissner effect.
How it works and high-temperature superconductors
In 1957 John Bardeen, Leon Cooper and Robert Schrieffer explained the mechanism with BCS theory: at low temperature, electrons pair up (Cooper pairs) via vibrations of the crystal lattice and move as a single quantum state without scattering. It is quantum mechanics visible at everyday scale, as strange in its way as quantum entanglement. When IBM's Georg Bednorz and Alex Müller found 35 K superconductivity in a copper oxide in 1986, they won the Nobel Prize the following year, and in 1987 YBCO reached 92 K, above the boiling point of cheap liquid nitrogen (77 K). The exact mechanism of high-temperature superconductivity is still not fully understood.
Applications and the room-temperature dream
Superconductors are already part of daily life. Hospital MRI scanners use superconducting electromagnets, and Japan's Chuo Shinkansen maglev, the discovery of the Higgs boson at CERN's Large Hadron Collider and fusion devices such as Korea's KSTAR all rely on superconducting magnets, though deep cooling makes them costly. In July 2023 a Korean team claimed LK-99 was a room-temperature, ambient-pressure superconductor, sparking global excitement and a stock frenzy, but replication attempts found neither zero resistance nor the Meissner effect, and the partial levitation was traced to copper sulfide impurities. A room-temperature superconductor remains physics' holy grail.
FAQ
- So LK-99 was not a superconductor?
- Correct. Multiple studies, including a verification committee of the Korean Society of Superconductivity and Cryogenics, concluded it is not. Its sudden resistance drop was explained by a phase transition in copper sulfide impurities.
- What would a room-temperature superconductor change?
- It could eliminate power-line losses and slash cooling costs for MRI, maglev trains and fusion reactors, transforming energy and transport. No room-temperature, ambient-pressure superconductor has been confirmed yet.
Sources reviewed: 2026-10-26
References
- Onnes, H. K. (1911). The resistance of pure mercury at helium temperatures. Communications from the Physical Laboratory of the University of Leiden, 120b.
- Bardeen, J., Cooper, L. N., & Schrieffer, J. R. (1957). Theory of superconductivity. Physical Review, 108(5), 1175–1204.
- Bednorz, J. G., & Müller, K. A. (1986). Possible high Tc superconductivity in the Ba–La–Cu–O system. Zeitschrift für Physik B, 64(2), 189–193.