Phase transformation by superoxygenation in cuprate and iridate thin films

ORAL

Abstract

High-pressure O2 has previously been used to hole-dope and stabilize high-oxidation phases of cuprates. We extend this superoxygenation technique to materials in thin film form since they are more reactive due to their large surface-to-volume ratio. YBa2Cu3O7-δ (YBCO) thin films grown by PLD are annealed in up to 700 atm O2 and then characterized by TEM, XRD and XAS. The annealed films show phase conversion to Y2Ba4Cu7O15-δ and Y2Ba4Cu8O16, as well as regions well as regions of YBa2Cu5O9-δ and YBa2Cu6O10-δ. Epitaxial thin films of Sr2IrO4 are subjected to extended high-pressure annealing and similarly characterized. The post-annealed films show up to 3 order-of-magnitude drop in room temperature resistivity and an evolution towards semi-metallic behaviour. Furthermore, as film thickness is reduced, the annealed films show a structural transformation towards a quasi-cubic phase. Our results demonstrate the potential of using superoxygenation to stabilize exotic phases of transition metal oxides not achievable in bulk form and to create novel materials by selectively transforming constituent layers in multilayer films. [1]
[1] H. Zhang et al., Phys. Rev. Materials 2, 033803 (2018).

*Work supported by NSERC, CFI-OIT and the Canadian Institute for Advanced Research

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Presenters

  • Chao C Zhang

    • Univ of Toronto
    • Department of Physics, University of Toronto

Authors

  • Chao C Zhang

    • Univ of Toronto
    • Department of Physics, University of Toronto

  • Hao Zhang

    • Department of Physics, University of Toronto

  • Nicolas Gauquelin

    • Electron Microscopy for Materials Science, University of Antwerp
    • Canadian Centre for Electron Microscopy and Department of Materials Science and Engineering, McMaster University

  • Shaobo Cheng

    • Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory
    • Canadian Centre for Electron Microscopy and Department of Materials Science and Engineering, McMaster University

  • Gianluigi Botton

    • Canadian Centre for Electron Microscopy and Department of Materials Science and Engineering, McMaster University

  • Christopher McMahon

    • Department of Physics and Astronomy, University of Waterloo

  • David Geoffrey Hawthorn

    • Department of Physics and Astronomy, University of Waterloo

  • Patrick Clancy

    • Department of Physics, University of Toronto

  • Saehwan Chun

    • Department of Physics, University of Toronto

  • Ambrose Seo

    • Department of Physics and Astronomy, University of Kentucky
    • University of Kentucky

  • Young-June Kim

    • Physics, University of Toronto
    • Department of Physics, University of Toronto

  • John Y.T. Wei

    • Univ of Toronto
    • University of Toronto
    • Department of Physics, University of Toronto