X-ray imaging of ionically-controlled nanoscale phase separation in cobaltites

ORAL

Abstract

Controlling ionic distributions and stoichiometry provides a unique way for manipulating functional properties in perovskite oxides (ABO3). This talk will focus on Gd/La0.67Sr0.33CoO3 (LSCO) heterostructures due to high oxygen ion conductivity, as well as the coupled magnetic and electronic properties of LSCO, which are strongly dependent on the oxygen stoichiometry. This enables the ionic control of the functional properties of LSCO thin films through the presence of oxygen getter layers such as Gd. We utilize x-ray nanodiffraction to directly image the nanoscale morphology of LSCO thin films as they are progressively transformed from the equilibrium perovskite phase to the metastable brownmillerite (ABO2.5) phase with increasing Gd thickness. Our studies show the coexistence of perovskite and brownmillerite phases with a critical oxygen vacancy concentration threshold which leads to the formation of extended brownmillerite filaments. In addition to lateral phase separation, we observed phase separation along the thin film thickness due to pinning of perovskite or brownmillerite by substrate/LSCO or Gd/LSCO interface respectively. Our measurements highlight local structural effects and provide insights into nanoscale strain behavior in Gd/LSCO heterostructures

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Presenters

  • Roopali Kukreja

    Materials Science and Engineering, Uinversity of California, Davis, University of California, Davis, Materials Science and Engineering, University of California Davis

Authors

  • Geoffery Ian Rippy

    Materials Science and Engineering, Uinversity of California, Davis, University of California, Davis, Materials Science and Engineering, University of California Davis

  • Lacey L Trinh

    University of California, Davis, Materials Science and Engineering, University of California Davis

  • Alexander Michael Kane

    University of California, Davis, Materials Science and Engineering, University of California Davis, Materials Science and Engineering, University of California, Davis

  • Aleksey Ionin

    University of California, Davis, Materials Science and Engineering, University of California Davis

  • Michael Steven Lee

    University of California, Davis, Materials Science and Engineering, University of California Davis, Materials Science and Engineering, University of California, Davis

  • Rajesh V Chopdekar

    University of California, Davis, Materials Science and Engineering, University of California Davis, Advanced Light Source, Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA, LBNL Advanced Light Source

  • Dustin Gilbert

    National Institute of Standards and Technology, NIST Center for Neutron Research, NIST Gaithersburg, Department of Materials Engineering, University of Tennesse, Knoxville

  • Alexander Grutter

    National Institute of Standards and Technology, NIST, NIST Center for Neutron Research, NIST Gaithersburg, Neutron-Condensed Matter Science Group, NIST, NIST Center for Neutron Research

  • Peyton Murray

    University of California, Davis, Physics, University of California Davis

  • Martin Holt

    Argonne National Laboratory, Center for Nanoscale Materials, Argonne National Laboratory, Advanced Photon Source, Argonne National Laboratory

  • Zhonghou Cai

    Argonne National Laboratory, Advanced Photon Source, Argonne National Laboratory

  • Kai Liu

    University of California, Davis, Physics, University of California Davis

  • Yayoi Takamura

    University of California, Davis, Materials Science and Engineering, University of California Davis, Materials Science and Engineering, University of California, Davis

  • Roopali Kukreja

    Materials Science and Engineering, Uinversity of California, Davis, University of California, Davis, Materials Science and Engineering, University of California Davis