Large Interlayer Relaxation at a Metal-Oxide Interface:The Case of a Supported Ultrathin Alumina Film

The structure of the metal-oxide interface in the alumina/Ni3Al(111) system is investigated by comparing backscattering and forward-scattering photoelectron diffraction modulation functions of chemically nonequivalent aluminum and oxygen species with multiple-scattering simulations. We observe large relaxation effects at the metal-oxide interface layer: Al atoms of the Ni3Al alloy surface are lifted by more than 0.7 Å above the ideal termination, thus creating a new, metallic layer between the oxide and the alloy. The effect of the interface atomic rearrangement on the properties of the supported ultrathin alumina oxide film is discussed.