Quantum nature of two-dimensional electron gas confinement at LaAlO$_{3}$/SrTiO$_{3}$ interfaces

ORAL

Abstract

Replace this text with your abstract body. The discovery of highly conducting interface between two insulating oxides LaAlO$_{3}$ and SrTiO$_{3}$ has attracted significant interest due to possible applications in all-oxide electronic devices. The two-dimensional electron gas (2DEG) formed at LaAlO$_{3}$/SrTiO$_{3}$ interfaces exhibits extremely high mobility and high density of carriers. Stimulated by this discovery we perform density functional calculations to understand the mechanism controlling the confinement width of the two-dimensional electron gas (2DEG) at LaAlO$_{3}$/SrTiO$_{3}$ interfaces. We find that the 2DEG confinement can be explained by the formation of metal induced gap states (MIGS) in the band gap of SrTiO$_{3}$. These states are formed as the result of quantum-mechanical tunneling of the charge created at the interface due to electronic reconstruction. The penetration depth of the MIGS into the insulator is controlled by the lowest-decay-rate evanescent states of SrTiO$_{3}$, as determined by its complex band structure. Our calculations predict that the 2DEG is confined in SrTiO$_{3}$ within about 1 nm at the interface.

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Authors

  • Karolina Janicka

    • Department of Physics and Astronomy, University of Nebraska Lincoln

  • J.P. Velev

    • Department of Physics, Institute for Functional Nanomaterials, University of Puerto Rico
    • University of Puerto Rico
    • University of Puerto Rico, San Juan, USA

  • Evgeny Tsymbal

    • Department of Physics and Astronomy, University of Nebraska Lincoln
    • University of Nebraska
    • Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska, USA
    • Department of Materials Science and Engineering, Tsinghua University, Beijing, China
    • University of Nebraska, Lincoln, USA
    • University of Nebraska, Lincoln NE, USA