STRUCTURAL AND ELECTRONIC-PROPERTIES OF TRANSITION-METAL BATIO3(001) INTERFACES/

Electronic and structural properties of transition-metal/BaTiO3(001) i nterfaces are studied by first-principles local-density full-potential linearized augmented plane-wave calculations with slab models. Equili brium inter layer separations between metal overlayers (for the 5d met als Ta, W, Ir, and Pt) and the BaTiO3 substrate are calculated by tota l-energy determinations. It is found that the preferred adsorption:sit e for metal atoms on the BaTiO3 surface is above the O site and the me tal-oxygen distance increases from Ta to Pt while the binding energy d ecreases. Significant hybridization is found between metal d states an d the O 2p-Ti 3d states. The Fermi levels of the metals lie in the gap of BaTiO3 and metal-induced gap states, as suggested by Heine's theor y [Proc. Phys. Sec. London 81, 300 (1962); Surf. Sci. 2, 1 (1964); Phy s. Rev. 138, A1689 (1965)], are observed. The Schottky barrier in the interfaces is calculated by the position of E-F in the gap and the dep endence of the barrier height on the metal work function is different from either Schottky and Mott's or Bardeen's [Phys. Rev. 71, 717 (1947 )] speculation.