High-temperature superconductivity doesn't happen all it once. It starts in isolated nanoscale patches that gradually expand until they take over. That discovery, from atomic-level observations at Cornell and the University of Tokyo, offers a new insight into the puzzling "pseudogap" state observed in high-temperature superconductors; it may be another step toward creating new materials that superconduct at temperatures high enough to revolutionize electrical engineering.
Scanning tunneling microscope image of a partially doped cuprate superconductor shows regions with an electronic "pseudogap" (rounded rectangle) others with no progress from the original insulator (dashed circles). As doping increases, pseudogap regions spread and connect, making the whole sample a superconductor.
Superconductivity, in which an electric current flows with zero resistance, was first discovered in metals cooled very close to absolute zero (-273 degrees Celsius). New materials called cuprates — copper oxides "doped" with other atoms — superconduct as "high" as -123 Celsius.