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Cooperative evolution of polar distortion and nonpolar rotation of oxygen octahedra in oxide heterostructures

Invited

Abstract

The polarity discontinuity across LaAlO 3 /SrTiO 3 (LAO/STO) heterostructure induces
electronic reconstruction involving the formation of two-dimensional electron gas (2DEG).
The heterostructure also exhibits structural distortion in close correlation with the 2DEG
formation, which can be characterized by either antiferrodistortive (AFD) rotation,
ferroelectric (FE) distortion, or both. Here, by using density functional theory (DFT)
calculations, we show that the AFD and FE modes are cooperatively coupled in the (111)-
oriented LAO/STO heterostructure; they coexist below the critical thickness (t c ) and
disappear simultaneously above t c with the formation of 2DEG. Electron energy loss
spectroscopy simulation of the O-K edge provide direct evidence of oxygen vacancy (V O )
formation at the LAO (111) surface, which acts as the source of 2DEG. Tracing the AFD
rotation and FE distortion of LAO from the interface to the surface reveals that their
evolution is strongly correlated with the V O distribution. The present study demonstrates that
the AFD and FE modes in an oxide heterostructure emerge as a consequence of the intricate
interplay of the interface orientation, lattice misfit strain, and internal polar field; it further
demonstrates that their combination can drive competitive or cooperative coupling by tuning
the relative evolution of the two modes.

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Presenters

  • Jaekwang Lee

    Pusan Natl Univ, Department of Physics, Pusan National University

Authors

  • Jaekwang Lee

    Pusan Natl Univ, Department of Physics, Pusan National University

  • Taewon Min

    Pusan Natl Univ, Department of Physics, Pusan National University

  • Jinsol Seo

    Sungkyunkwan University, Sungkyunkwan Univ.

  • Gyeongtak Han

    Sungkyunkwan Univ., Department of Energy Sciences, Sungkyunkwan University

  • Young-Min Kim

    Sungkyunkwan Univ., Department of Energy Sciences, Sungkyunkwan University

  • Sang Ho Oh

    Sungkyunkwan University, Sungkyunkwan Univ.

  • Hu Young Jeong

    Ulsan National Institute of Science and Technology, UNIST Central Research Facilities and School of Materials Science and Engineering, Ulsan National Institute of Science and Technology

  • Hyungwoo Lee

    Materials Science and Engineering, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin-Maddison, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Jungwoo Lee

    Materials Science and Engineering, University of Wisconsin-Madison, University of Wisconsin, Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison,, University of Wisconsin, University of Wisconsin-Madison, University of Wisconsin-Maddison, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Kitae Eom

    Materials Science and Engineering, University of Wisconsin-Madison, Department of Materials Science and Engineering, University of Wisconsin-Maddison, Department of Materials Science and Engineering, University of Wisconsin, Department of Materials Science Engineering, University of Wisconsin-Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison,, University of Wisconsin, Material Science and Engineering, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin-Maddison

  • Chang-Beom Eom

    Materials Science and Engineering, University of Wisconsin-Madison, University of Wisconsin, Madison, Department of Materials Science and Engineering, University of Wisconsin-Maddison, Department of Materials Science and Engineering, University of Wisconsin, Department of Materials Science Engineering, University of Wisconsin-Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison,, University of Wisconsin, Material Science and Engineering, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin-Maddison, University of Wisconsin - Madison, University of Wisconsin Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Wooseon Choi

    Sungkyunkwan Univ

  • Kyung Song

    Korea Institute of Materials Science

  • Sangwoo Ryu

    University of Wisconsin-Madison