  First-principles calculations demonstrate the evolution of the band alignment
at La0.7A0.3MnO3|La1-xAx|TiO2|SrTiO3(001) heterointerfaces, where A = Ca, Sr,
or Ba, as the interfacial A-site composition, La1-Ax, is varied from x = 0.5 to
x = 1.0. This variation leads to a linear change of the SrTiO3 valence band
offset with respect to the Fermi level of the La0.7A0.3MnO3 metal electrode and
hence to a linear change of the Schottky barrier height at this interface. The
effect arises due to electrostatic screening of the polar interface which
alters the interfacial dipole and hence the electrostatic potential step at
this interface. We find that both the La0.7A0.3MnO3 and SrTiO3 layers
contribute to screening with both electronic and ionic screening being
important for the change in the interface dipole. The results are in agreement
with the recent experimental data.
