Evolution of the band alignment at polar oxide interfaces

Authors

John D. Burton, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow

Date of this Version

2010

Citation

PHYSICAL REVIEW B 82, 161407(R) (2010). DOI: 10.1103/PhysRevB.82.161407

Comments

Copyright © 2010 American Physical Society. Used by Permission

Abstract

First-principles calculations demonstrate the evolution of the band alignment at La_0.7A_0.3MnO₃ / La_1−xA_xO / TiO₂ / SrTiO₃ (001) heterointerfaces, where A=Ca, Sr, or Ba, as the interfacial A-site composition, La_1−xA_x, is varied from x=0.5 to x=1.0. This variation leads to a linear change in the SrTiO₃ valence-band offset with respect to the Fermi level of the La_0.7A_0.3MnO₃ 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 La_0.7A_0.3MnO₃ 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.