| The fabrication of well controlled heterointerfaces is the cornerstone for much of modem microelectronics. High quality interfaces of novel materials, particularly of the correlated transition metal oxides, enable the creation of structures with rich and surprising phenomena. In this thesis, we present two epitaxial interfaces in which atomic scale details control the properties of the structure. (1) MBE grown BaO/Si is a prototype for the epitaxial oxide/silicon interface, which is of interest for future generations of MOSFET devices. Using a combination of synchrotron X-ray diffraction, TEM, RHEED and first principles calculations, we identify a sub-Angstrom rumpling reconstruction at the interface which elucidates how the sharp transition from a diamond covalent lattice to ionic rocksalt occurs. (2) La1- xSrxMnO3 is a CMR oxide. By manipulation of its composition, strain, thickness and carrier distribution we are able to achieve a large resonant coupling between the oxygen octahedra rotation of a SrTiO3 substrate and a La1- xSrxMnO3 film. The divergence of the rotation amplitude at the structural transition of the SrTiO3 leads to pronounced changes in the transport and magnetic properties of the film. We describe the mechanical coupling using a quantitative atomic model and explain it as the result of the role of octahedra orientation in La1-xSrxMnO 3. |
