Thermally activated domain boundary formation on a missing row reconstructed surface: Au(1 1 0)

In this paper we describe the observation of the spontaneous, thermally activated formation of domain boundaries in the missing row reconstruction of Au(1 1 0) obtained with scanning tunneling microscopy (STM). The domain boundaries nucleate at two special sites on the surface: termination sites, where four steps annihilate in one point, and crossing sites, where two steps cross each other. In order to determine the domain boundary formation energies, we describe their length distributions by a simple theory, which accounts not only for the formation energy of the domain boundary, but also for the change in free energy of the steps in the vicinity of the boundary. An even better description is obtained by including also elastic step–step interactions. In both cases, we derive very low domain boundary energies. Combining this information with the formation energies of steps and kinks on the Au(1 1 0)-surface, obtained in previous studies, we test theoretical models of the two disordering phase transitions that this surface exhibits: deconstruction and roughening. This paper reports the last observation of a series, in which the energetics on Au(1 1 0) has been studied; we add an overview of the experimentally obtained energy values.