In superconducting materials, the electric current flows without energy dissipation (zero electrical resistance). This happens only below a so-called critical temperature Tc. The cuprates are a singular family of materials whose Tc is relatively high (~ tens of K). Another of their very unique properties is that the Tc can enhanced by shining light on them. Interestingly, such photoinduced enhancement of superconductivity is persistent as long as the material is not warmed up. The mechanisms for this unique phenomenon have been debated since its discovery three decades ago. Up to now, most of the existing models consider that the Tc enhancement is linked to a photoinduced increase in the number of conducting electrons. Here we show experimental evidence that the most important ingredient is instead a light-induced enhancement of the electrons’ mobility, which can be explained by a photoinduced ordering of oxygen atoms in the crystal structure. Besides providing new understanding on a longstanding problem, our results provide new evidence for the intimate relation between critical temperature and scattering rate, a key ingredient in modern theories on high-temperature superconductivity.

Disentangling Photodoping, Photoconductivity, and Photosuperconductivity in the Cuprates
R. El Hage et al.
Phys. Rev. Lett. 132, 066001 (2024)