Observation of a Soliton Reconstruction of Au(111) by High-Resolution Helium-Atom Diffraction

From an analysis of diffraction data for Au(111), we deduce that the observed 23-fold periodicity in the $〈110〉$ direction can be described by a regular superstructure of one-dimensional extended stacking faults. We propose that this surface is a realization of the Frenkel-Kontorova model of competing interactions and that the periodic changes in stacking from ABC to ABA may thus take the form of solitons. The solitons, of half-width 11.8 {}, lead to an average compression of 4% in the $〈110〉$ direction.