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Ionically-controlled phase separation in cobaltite heterostructures

ORAL

Abstract

Controlling ionic distribution and stoichiometry in complex oxide heterostructures has been utilized to significantly alter and tune functional properties. Recently, deposition of a strong oxygen getter on top of an oxide thin film has emerged as a novel way to tailor oxygen stoichiometry and nanoscale functional properties. In this talk, I will focus on Gd/La0.67Sr0.33CoO3 (LSCO) heterostructures due to the high oxygen ion conductivity, as well as the coupled magnetic and electronic properties of LSCO, which are strongly dependent on the oxygen stoichiometry. This combination of properties enable 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 (BM) phase with increasing Gd thickness. Our studies show the coexistence of perovskite and BM phases with a critical oxygen vacancy concentration threshold which leads to the formation of extended BM filaments. Our studies provide an unprecedented nanoscale survey of the phase separation in the cobaltites and shed light on the formation of the metastable BM phase.

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Presenters

  • Roopali Kukreja

    University of California, Davis

Authors

  • Geoffery I Rippy

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

  • Lacey L Trinh

    University of California, Davis

  • Alexander Michael Kane

    University of California, Davis

  • Aleksey Ionin

    University of California, Davis

  • Michael Lee

    University of California, Davis

  • Rajesh V Chopdekar

    Advanced Light Source, Lawrence Berkeley National Lab, University of California, Davis, Lawrence Berkeley National Laboratory

  • Joyce Christiansen-Salameh

    University of California, Davis

  • Dustin Gilbert

    University of Tennessee, Department of Materials Science and Engineering, University of Tennessee, Material Science and Engineering, University of Tennessee, Knoxville

  • Alexander Grutter

    National Institute of Standards and Technology, Center for Neutron Research, National Institute of Standards and Technology, NIST Center for Neutron Research, NIST, NIST Gaithersburg

  • Peyton Murray

    University of California, Davis

  • Martin Holt

    Center for nanoscale materials, Argonne National Laboratory, Argonne National Laboratory, Argonne National Lab

  • Zhonghou Cai

    Argonne National Laboratory

  • Kai Liu

    Georgetown University, Physics Department, Georgetown University, Washington, DC, USA

  • Yayoi Takamura

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

  • Roopali Kukreja

    University of California, Davis