Doping- and Strain-Dependent Electrolyte-Gate-Induced Perovskite to Brownmillerite Transformation in Epitaxial La<sub>1-x</sub>Sr<sub>x</sub>CoO<sub>3-δ</sub> Films

ORAL

Abstract

The reversible topotactic transformation between perovskite (P) SrCoO3-δ and oxygen-vacancy-ordered brownmillerite (BM) SrCoO2.5 has attracted much attention recently due to wide modulation of electronic, magnetic, and optical properties, particularly when voltage-triggered in electrolyte gating. SrCoO3 is relatively unstable, however, and there has been little exploration of alternate compositions. Here, we present the first study of ion-gel-gating-induced P to BM transformations across almost the entire La1-xSrxCoO3-δ phase diagram (0 < x < 0.7). Electronic transport, magnetometry, and operando synchrotron X-ray diffraction establish the P to BM transformation at nearly all x, including x < 0.5, where both P and BM are highly air-stable. The transformation threshold voltage decreases significantly with x, but also with epitaxial strain (both tensile and compressive), providing desirable tunability for devices. These results are analyzed in the context of oxygen vacancy formation energies, diffusion coefficients, and recent theory, establishing that thermodynamics, not kinetics, underpins the decrease of the threshold voltage with x. These findings substantially advance the understanding of this voltage-driven transformation, with both fundamental and technological implications.

*Work at UMN primarily supported by the NSF through the UMN MRSEC under DMR-2011401.

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Publication: Publications derived from this work:
Chaturvedi, V., Postiglione, W. M., Chakraborty, R. H., Yu, B., Tabis, W., Hameed, S., Biniskos, N., Jacobson, A., Zhang, Z., Zhou, H., Greven, M., Ferry, V. E., Leighton, C., Doping- and Strain-Dependent Electrolyte-Gate-Induced Perovskite to Brownmillerite Transformation in Epitaxial La1-xSrxCoO3-δ Films. ACS Appl. Mater. Interfaces. In press, 2021

Presenters

  • William M Postiglione

    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, USA

Authors

  • William M Postiglione

    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, USA

  • Vipul Chaturvedi

    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, USA

  • Rohan D Chakraborty

    • University of Minnesota

  • Biqiong Yu

    • University of Minnesota
    • School of Physics and Astronomy, University of Minnesota

  • Wojciech Tabis

    • AGH University of Science and Technology, Krakow, Poland

  • Sajna Hameed

    • University of Minnesota
    • School of Physics and Astronomy, University of Minnesota

  • Nikolaos Biniskos

    • University of Minnesota
    • School of Physics and Astronomy, University of Minnesota

  • Andrew Jacobson

    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, USA

  • Zhan Zhang

    • Argonne National Laboratory
    • Advanced Photon Source, Argonne National Laboratory
    • Argonne National Lab

  • Hua Zhou

    • Argonne National Laboratory

  • Martin Greven

    • University of Minnesota
    • School of Physics and Astronomy, University of Minnesota

  • Vivian E Ferry

    • University of Minnesota

  • Chris Leighton

    • University of Minnesota
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, USA