First-principles calculations demonstrate the evolution of the band alignment at ${\text{La}}_{0.7}{A}_{0.3}{\text{MnO}}_3\left|{\text{La}}_{1-x}{A}_x\text{O}\right|{\text{TiO}}_2\mid {\text{SrTiO}}_3\left(001\right)$ heterointerfaces, where $A=\text{Ca}$, Sr, or Ba, as the interfacial $A$-site composition, ${\text{La}}_{1-x}{A}_x$, is varied from $x=0.5$ to $x=1.0$. This variation leads to a linear change in the ${\text{SrTiO}}_3$ valence-band offset with respect to the Fermi level of the ${\text{La}}_{0.7}{A}_{0.3}{\text{MnO}}_3$ metal electrode and hence to a linear change in the Schottky barrier height at this interface. The effect arises due to electrostatic screening of the polar interface, altering the interfacial dipole and hence the electrostatic potential step at this interface. We find that both the ${\text{La}}_{0.7}{A}_{0.3}{\text{MnO}}_3$ and ${\text{SrTiO}}_3$ 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.

• Received 8 July 2010

DOI:https://doi.org/10.1103/PhysRevB.82.161407