Quantum Nature of Two-dimensional Electron Gas Confinement at LaAlO₃=SrTiO₃ Interfaces

Authors

• Karolina Janicka, University of Nebraska - Lincoln
• Julian P. Velev, University of Nebraska-LincolnFollow
• Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow

ORCID IDs

Tsymbal http://orcid.org/0000-0002-6728-5503

Document Type

Article

Date of this Version

3-13-2009

Citation

Physical Review Letters (2009) 102: 106803

Comments

Copyright © 2009, American Physical Society. Used by permission

Abstract

We perform density functional calculations to understand the mechanism controlling the confinement width of the two-dimensional electron gas (2DEG) at LaAlO₃/SrTiO₃ interfaces. We find that the 2DEG confinement can be explained by the formation of metal induced gap states (MIGS) in the band gap of SrTiO₃. These states are formed as the result of quantum-mechanical tunneling of the charge created at the interface due to electronic reconstruction. The attenuation length of the MIGS into the insulator is controlled by the lowest-decay-rate evanescent states of SrTiO₃, as determined by its complex band structure. Our calculations predict that the 2DEG is confined in SrTiO₃ within about 1 nm at the interface.