Fy. Rao et al., STRUCTURAL AND ELECTRONIC-PROPERTIES OF TRANSITION-METAL BATIO3(001) INTERFACES/, Physical review. B, Condensed matter, 55(20), 1997, pp. 13953-13960
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.