Origin of Modified Interface Dielectric Properties in BFO Thin Films

ORAL

Abstract

BiFeO$_{3}$ - La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (BFO-LSMO) interfaces were investigated by high-resolution scanning transmission electron microscopy (STEM) revealing a local suppression of the octahedral tilts and local increase of the out-of-plane lattice parameter. The combination of direct structural mapping using bright field and annular dark field images with electron energy loss spectroscopy (EELS) was used to correlate the atomic structure, polarization, strain fields and dielectric behavior locally on the atomic level. EELS compositional mapping at the interfaces used principal component analysis combined with neural network interpolation. In the low loss energy region the BFO side of the interface could not be identified with BFO, LSMO or STO (SrTiO$_{3})$, suggesting that the first 2 nm of BFO has modified dielectric properties. First principles calculations show that the observed suppression of octahedral tilts results in a decreasing BFO band gap or possibly even metallic behavior.

*The research is sponsored by the U.S. DOE Division of Materials Sciences and Engineering.

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Authors

  • Albina Borisevich

    • Oak Ridge National Laboratory

  • Hye Jung Chang

    • Oak Ridge National Laboratory

  • Mark Huijben

    • University of Twente
    • MESA+ Institute for Nanotechnology, University of Twente, The Netherlands

  • M.P. Oxley

    • Oak Ridge National Laboratory
    • Vanderbilt Univ.

  • S. Okamoto

    • Oak Ridge National Laboratory

  • Manish Niranjan

    • University of Nebraska Lincoln

  • John Burton

    • University of Nebraska Lincoln

  • Evgeny Tsymbal

    • University of Nebraska Lincoln

  • Ying Hao Chu

  • P. Yu

    • Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California Berkeley
    • Department of Physics, UC Berkeley

  • R. Ramesh

    • University of California, Berkeley
    • Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California Berkeley
    • Department of Physics, UC Berkeley

  • Sergei Kalinin

    • Oak Ridge National Laboratory
    • Oak Ridge National Laboratory, Oak Ridge, TN 37831
    • ORNL, Oak Ridge, TN

  • S. J. Pennycook

    • Oak Ridge National Laboratory
    • Oak Ridge National Laboratory, Oak Ridge TN 37831
    • Materials Science \& Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Oak Ridge Natl. Lab.