Determination of the electronic structure of ferroelectric surfaces by scanning tunneling microscopy

Abstract

The electronic structures and the origin of the in-gap states of the BaTiO3 (001) (2 × 2), (√5 × √5), and (3 × 1) reconstructions are investigated using scanning tunneling microscopy and low energy electron diffraction. We find a shift of the in-gap states toward the valence band as the order of the reconstructions increase. We argue that Ti adatoms are responsible for the in-gap state, and a decrease in the oxidation state of the Ti adatom as a function of the reconstruction is attributed to the shift of the in-gap state within the local density of states.