13. November 2015
Excited states at interfaces of a metal-supported ultrathin oxide film
Metal-supported ultrathin oxide ﬁlms such as MgO/Ag(001) are a class of materials of technological importance in various research ﬁelds such as catalysis, spintronics, or nanoelectronics. At the ultrathin limit of three monolayers, due to the different environment, each layer develops different electronic characteristics. At the PEARL beamline, researchers have used Resonant Auger electron spectroscopy near the Mg K edge to identify the local density of empty Mg p states in each individual layer. While the middle layer shows the normal oxide band gap known from the bulk material, the gap is filled by metal-induced gap states at the metal/oxide interface. At the oxide/vacuum interface, the optical gap is reduced by a surface-core exciton involving an image potential state in the vacuum. Using the core-hole clock method, the lifetime of this surface-core exciton of 5 fs has been measured.
Schematic of layer-specific electronic states in the bulk band gap of ultrathin magnesium oxide at the metal/oxide and the oxide/vacuum interfaces.
Original PublicationExcited states at interfaces of a metal-supported ultrathin oxide film
T. Jaouen, E. Razzoli, C. Didiot, G. Monney, B. Hildebrand, F. Vanini, M. Muntwiler, and P. Aebi
Phys. Rev. B 91, 161410 (2015), published 23 April 2015
ContactDr Matthias Muntwiler
Laboratory for Synchrotron Radiation — Condensed Matter Physics
Swiss Light Source, Paul Scherrer Institute
5232 Villigen PSI, Switzerland
Phone: +41 56 310 5138, e-mail: firstname.lastname@example.org