Interface structure of SrTiO3-LaAlO3 at elevated temperatures studied in-situ by synchroton x-rays

The atomic interface structure between SrTiO3 and LaAlO3 was studied at elevated temperatures employing in situ surface x-ray diffraction. The results at 473 K indicate that the lattice distorts significantly in two ways. First, the interatomic distances between the cations across the interface become as large as 4.03(2) Å. Second, the TiO6 octahedra at the interface contract their principal axis along the surface normal considerably and the Ti displaces off center. These distortions can be ascribed to the charge inbalance introduced by the change in atomic species across the interface and to a Jahn-Teller effect. The latter distortion suggests the presence of extra electrons at the interface, which is important for understanding the electronic properties of this system

Initial Structure and Growth Dynamics of YBa2Cu3O7-d during Pulsed Laser Deposition

The initial heteroepitaxial growth of YBa2Cu3O7-delta films on SrTiO3(001) substrates during pulsed laser deposition shows a growth-mode transition and a change of growth unit. The growth starts with two blocks, each two-thirds the size of the complete unit cell. The first of these blocks grows in a step-flow fashion, whereas the second grows in the layer-by-layer mode. Subsequent deposition occurs layer-by-layer of complete unit cells. These results suggest that the surface diffusion in the heteroepitaxial case is strongly influenced by the competition with formation energies, which is important for the fabrication of heteroepitaxial devices on the unit cell scale