Surface reconstruction of BaTiO3 (001)

Whether spatially ordered surface structure interacts with ferroelectric ordering is very important and remains an open question. In order to study the interactions between ferroelectric domains and surface reconstruction, STM and non-contact AFM were used to investigate (001) surface of single crystal BaTiO3. BaTiO3 (001) undergoes dramatic morphological evolution upon UHV annealing. The uppermost atoms rearrange into a variety of periodic structures at this surface depending on the thermo-chemical history. Superstructures, including the c(2×2), (2×1), c(4×4), (2×2), (r5xr5)R26.6o and a series that evolves into (3×1) or (3×2) nano-stripes have been identified by LEED. Atomic resolved STM images of (r5×r5)-R26.6o, (3×1) and (3×2) surface superstructures have been obtained for the first time. A mechanism based on ordered Ba-adatom is proposed to explain the formation of various surface reconstructions. The reconstruction has not been found to affect the ferroelectric nature of the surface to the first order.