Reversible Transition Between Thermodynamically Stable Phases with Low Density of Oxygen Vacancies on SrTiO${}_3$(110) Surface

The surface reconstruction of SrTiO${}_3$(110) is studied with scanning tunneling microscopy and density functional theory (DFT) calculations. The reversible phase transition between (4$\times$1) and (5$\times$1) is controlled by adjusting the surface metal concentration [Sr] or [Ti]. Resolving the atomic structures of the surface, DFT calculations verify that the phase stability changes upon the chemical potential of Sr or Ti. Particularly, the density of oxygen vacancies is low on the thermodynamically stabilized SrTiO${}_3$(110) surface.