Towards room-temperature superconductivity: Insights into optical properties of bi-based copper-oxide superconductors

Copper-oxide (CuO2) superconductors, such as Bi2Sr2CaCu2O8+ (Bi2212), have unusually high critical temperatures. Optical reflectivity measurements of Bi2212 have shown that it exhibits strong optical anisotropy. However, this has not been studied through optical transmittance measurements, which can offer more direct insights into bulk properties. Now, researchers have elucidated the origin of this optical anisotropy through ultraviolet and visible light transmittance measurements of lead-doped Bi2212 single crystals, enabling a more precise investigation into its superconductivity mechanisms.