We report on a systematic study of the growth of epitaxial TiO2 films
deposited by pulsed laser deposition on Ti-terminated (001) SrTiO3 single
crystals. By using in-situ reflection high energy electron diffraction, low
energy electron diffraction, x-ray photoemission spectroscopy and scanning
probe microscopy, we show that the stabilization of the anatase (001) phase is
preceded by the growth of a pseudomorphic Sr-Ti-O intermediate layer, with a
thickness between 2 and 4 nm. The data demonstrate that the formation of this
phase is related to the activation of long range Sr migration from the
substrate to the film. The role of interface Gibbs energy minimization, as a
driving force for Sr diffusion, is discussed. Our results enrich the phase
diagram of the Sr-Ti-O system under epitaxial strain opening the roudeficient
SrTiO phase.Comment: 8 pages, 7 figure