STEM Studies of Charge and Orbital Ordering in La<sub>0.6</sub>Sr<sub>2.4</sub>Mn<sub>2</sub>O<sub>7</sub> Manganite

ORAL

Abstract

Charge and orbital ordering typically occurs in perovskite-related oxides, and has been demonstrated to induce various interesting physical phenomena. La2−2xSr1+2xMn2O7 represents one of the most interesting manganites where its charge and orbital ordering can be tuned by varying x. Specifically, no long-range magnetic order of any type was found using neutron powder diffraction for 0.66 ≤ x ≤ 0.72 in polycrystalline samples. In this study, we perform systematic scanning transmission electron microscopy (STEM) studies of charge and orbital ordering and local nano-scale phase competition in a La0.6Sr2.4Mn2O7 (x = 0.7) single crystal. By combining lattice strain quantification and valence state mapping at atomic scale for this crystal, we show that charge and orbital ordering at short-ranges can be probed using real-space imaging and spectroscopy. Charge ordering stripes of Mn3+ and Mn4+ are directly visualized by electron-energy loss spectroscopy and found to be spatially correlated with periodic picometer-level shear deformations via orbital ordering in Mn3+ stripes.

*Research supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division and ORNL's CNMS, which is a DOE Office of Science User Facility.

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Presenters

  • Qiang Zheng

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab

Authors

  • Qiang Zheng

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • Nathaniel Schreiber

    • Materials Science Division, Argonne National Laboratory

  • Hong Zheng

    • Materials Science Division, Argonne National Laboratory

  • Jiaqiang Yan

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Oak Ridge National Laboratory
    • Ames Laboratory, Iowa State University

  • Michael McGuire

    • Oak Ridge National Laboratory
    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • John Mitchell

    • Argonne Natl Lab
    • Materials Science Division, Argonne National Laboratory
    • MSD, Argonne National Laboratory
    • Argonne National Laboratory

  • Miaofang Chi

    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

  • Brian Sales

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Oak Ridge National Laborotary
    • Oak Ridge National Laboratory