Evolution of the surface structures on SrTiO3(110) tuned by Ti or Sr concentration

The surface structure of the SrTiO3(110) polar surface is studied by scanning tunneling microscopy and x-ray photoelectron spectroscopy. Monophased reconstructions in (5 x 1), (4 x 1), (2 x 8), and (6 x 8) are obtained, respectively, and the evolution between these phases can be tuned reversibly by adjusting the Ar+ sputtering dose or the amount of Sr/Ti evaporation. Upon annealing, the surface reaches the thermodynamic equilibrium that is determined by the metal concentration. The different electronic structures and absorption behaviors of the surface with different reconstructions are investigated.