Electron pair emission from a highly correlated material

Electron pair emission spectroscopy (e, 2e) is a tool well suited to probe the electron correlations. The probability of the electron pair emission depends in a crucial way on the localization properties of the electron wave functions describing the initial state of the system. One expects an enhanced coincidence signal from the localized electron states in oxides compared to that of itinerant states in metals. Our comparative (e, 2e) study of the Ag(001) and NiO/Ag(001) system confirms this observation. We demonstrate that the intensity of the pair emission increases by an order of magnitude after the deposition of 15 monolayers of NiO onto the Ag(001) substrate.