Physicists use electrical noise to solve superconductor mystery

A research team has utilised electrical noise to gain insight into the long-standing mystery of high-temperature superconductors. Led by Milan Allan of Ludwig Maximilian University of Munich and Ingmar Swart of Utrecht University in the Netherlands, the study was recently published in the journal Science.

Superconductors are materials capable of conducting electricity without resistance, though most require temperatures near absolute zero to function. Cuprates, which are copper-based materials, were discovered in the late 1980s to reach this state at higher temperatures using liquid nitrogen, yet the mechanism behind this remains debated after nearly 40 years.

The research team examined the faint electrical crackle produced as current flows into a cuprate material. This approach focuses on the pseudogap, a state described by Milan Allan as a phenomenon of missing electrons.

According to Milan Allan, some electrons appear to vanish above the temperature at which cuprates become superconducting, as measurements show fewer electrons than expected at certain energies. "The pseudogap is a phenomenon of missing electrons," Allan stated, adding, "Everybody knows that from different probes, you see that there's these vanishing electrons, but nobody knows why."