Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Oxide and insulator surfaces: Structure, epitaxy and growth I
O 52.5: Vortrag
Dienstag, 10. März 2026, 15:45–16:00, WILL/A317
Probing electron-transfer between layers of a CrOx/Pt(111) thin film via workfunction and adsorption measurements in the STM — •Ghada Missaoui1, Claudine Noguera2, Jacek Goniakowski2, and Niklas Nilius1 — 1Carl von Ossietzky University, Institute of Physics, D-26111 Oldenburg, Germany — 2CNRS-Sorbonne University, UMR 7588, INSP, F-75005 Paris, France
Low-temperature tunneling spectroscopy has been employed to probe the workfunction of atomically flat Cr-oxide single- and double-stack films grown on Pt(111). The single-stack Cr3O6 trilayer exhibits an exceptionally high workfunction of more than 7.0 eV, decreasing to 5.0 eV for Cr6O11 double-stacks. The charge redistribution behind this workfunction drop was analyzed by density functional theory. The high workfunction of Cr3O6 trilayers originates from a massive electron transfer from the Pt(111) support into empty Cr-states that reduces 2/3 of the oxide cations from their formal 4+ to a 3+ charge state. The negative surface dipole diminishes upon growing a Cr-O honeycomb plane on top of the trilayer, forming a Cr6O11 double-stack. The ad-layer acts as electron donor, allowing the charge transfer from the platinum to decrease substantially. The charge redistribution not only triggers the detected workfunction drop but also leads to a different reactivity of single- versus double-stack CrOx films, as demonstrated with MgPc adsorption experiments performed with the STM.
Keywords: Cr oxide; workfunction; charge transfer; adsorption