Atomic-Resolution Visualization of Complex Structures in Intercalated Bilayer Graphene

ORAL

Abstract

Intercalation in two-dimensional materials has been widely investigated using spectroscopic, diffraction, and electrical measurements. However, these techniques generate spatially averaged data and provide information about the local atomic structure only inferentially. In this work, we deploy aberration-corrected scanning transmission electron microscopy to directly visualize the local atomic structure of FeCl3-intercalated bilayer (BLG) and few-layer graphene (FLG). The data exhibit a crystalline monolayer of FeCl3 inside BLG, atomically sharp intercalation boundaries, a variety of orientations for FeCl3 monolayers in FLG, and regions where the iron is reduced to form monolayer FeCl2. Our density-functional-theory calculations predict a low energy barrier of 0.04 meV/nm2 between different orientations of FeCl3, supporting the observation of multiple orientations. Furthermore, resonant-Raman spectroscopy yields evidence of two distinct graphene doping levels of EF=0.98eV and EF=1.06 in intercalated bilayer graphene, which may be attributed to the coexistence of FeCl3 and FeCl2. These results highlight the critical need for atomic-resolution studies of FeCl3 and similar intercalants to understand the dynamics of doping in multilayer graphene and graphene superlattices.

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Presenters

  • Jason Bonacum

    Department of Physics and Astronomy, Vanderbilt University

Authors

  • Jason Bonacum

    Department of Physics and Astronomy, Vanderbilt University

  • Andrew O'Hara

    Physics, Vanderbilt University, Department of Physics and Astronomy, Vanderbilt University

  • Oleg S Ovchinnikov

    Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, Department of Physics and Astronomy, Vanderbilt University

  • Georgy Gordeev

    Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin

  • Sonakshi Arora

    Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin

  • Stephanie Reich

    Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin

  • Juan Carlos Idrobo

    Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, Oak Ridge National Laboratory

  • Richard F Haglund

    Vanderbilt University, Department of Physics and Astronomy, Vanderbilt University

  • Sokrates T Pantelides

    Department of Physics and Astronomy, Vanderbilt University, Vanderbilt University, physics, Vanderbilt University, Physics, Vanderbilt University, Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Dept. of Physics and Astronomy, Vanderbilt University, USA

  • Kirill Bolotin

    Department of Physics, Freie Universität Berlin, Germany, Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin