Some materials conduct electricity perfectly at temperatures no theory can explain

The problem

Conventional superconductivity — electrons pairing up via lattice vibrations and flowing without resistance — was explained by BCS theory and seemed confined to temperatures near absolute zero. Then in 1986 Bednorz and Müller found a ceramic copper oxide superconducting at 35 K, and within a year related 'cuprates' passed 77 K, the boiling point of cheap liquid nitrogen. BCS theory cannot account for these materials: the electrons pair through some other mechanism, entangled with magnetism and exotic phases, and four decades of intense effort have produced proposals but no accepted fundamental description. The 2019–2025 nickelate boom — nickel-oxide cousins superconducting up to ~90 K — has given theorists a whole second family to test their ideas against.

Why it matters

A verified mechanism could point the way to superconductors at everyday temperatures — lossless power grids, cheap MRI and maglev, and a transformed energy economy. It is also the flagship case of a broader failure: physics still can't handle strongly interacting electrons.

Progress so far

• 1986Bednorz and Müller discover superconductivity at 35 K in lanthanum barium copper oxide
• 1987YBCO superconducts above liquid-nitrogen temperature (77 K); Bednorz and Müller receive the Nobel Prize
• 2019superconductivity discovered in infinite-layer nickelates at Stanford, a first family beyond copper
• 2023bilayer nickelate La₃Ni₂O₇ superconducts up to ~90 K under high pressure
• 2024epitaxial strain makes bilayer nickelate thin films superconduct at ambient pressure, opening full experimental access

References

1. Nobel Prize — 1987 prize to Bednorz and Müller for superconductivity in ceramic materials
2. Physics Today (2025) — state of the field: the nickelate timeline and the still-unsettled pairing mechanism
3. Wikipedia — history from the 1986 discovery through the open mechanism question