Electronic states in faceted Au(111) studied with curved crystal surfaces.

Vicinal Au(111) surfaces exhibit periodic faceting within a wide range of miscut angles. There, the system segregates two alternating phases with different step lattice constants d(w) and d(n). Using a curved crystal surface that allows a smooth variation of the surface orientation, we have studied, as a function of the miscut angle, the evolution of Au(111) faceted structures by scanning tunneling microscopy, and their electronic surface states by angle-resolved photoemission. We observe that surface bands reflect the two-phase character of the faceted system, i.e. we find d(w)- and d(n)-like states that evolve accordingly to the faceted structure. Using a photoemission calculation we prove that the apparently complex topology hides relatively simple physics, i.e. the same free-electron-like dispersion and repulsive step scattering that feature surface bands in stepped noble metal surfaces. On the grounds of such simulations, we discuss the possible interference of the electronic energy in the delicate free energy balance that determines the critical size of reconstructed (d(w)) and unreconstructed (d(n)) terraces during Au faceting.