Adsorbate-induced faceting: The case of Ag on vicinal Cu surfaces

The driving forces of adsorbate-induced faceting of vicinal surfaces are investigated through a coupling between grazing-incidence x-ray diffraction experiments and atomic-scale simulations. This approach is applied to the adsorption of Ag onto Cu vicinal surfaces, for which a submonolayer deposition induces a faceting with the formation of Ag-covered and bare Cu facets. The atomic arrangement of the Ag-covered facets is obtained by coupling experiments and simulations, which allows the development of a realistic modeling of adsorbate-induced faceting. We find that the faceting results from the competition between the surface energies of the pure Cu faces and the adsorption energies of Ag atoms. Finally, we show that a reliable description of the system evolution is obtained only if a proper value of the step interaction energy is included within the model.