The two figures show the results obtained with a specialized scanning tunneling microscope at temperatures well above and well below when the electrons pair up in high temperature superconductors. The top figure shows an atomic scale map of the strength (delta) for pairing of electrons while superconducting, in which red shows the strongest pairing regions and blue the weakest. The bottom figure shows a measurement related to electron-electron interaction on the exact same atomic sites at a temperature, well above the superconducting transition temperature, when electrons repel one another. The surprising connection between these two measurements is the main finding of the paper published in Science by the team from Princeton.
Image: Yazdani Group