Superoxygenation study of cuprate and iridate thin films

ORAL

Abstract

High-pressure O2 has been used to hole-dope and to stabilize high-oxidation phases of cuprates. We extend this superoxygenation technique to YBa2Cu3O7-δ thin films, which are more reactive due to their large surface-to-volume ratio, and to the layered iridate Sr2IrO4, which is difficult to hole-dope by cation substitution. First, YBa2Cu3O7-δ 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 of YBa2Cu5O9-δ and YBa2Cu6O10-δ. Second, 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. [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

  • Hao Zhang

    • Department of Physics, University of Toronto

Authors

  • Hao Zhang

    • Department of Physics, University of Toronto

  • Chao Zhang

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

  • Nicolas Gauquelin

    • EMAT, University of Antwerp
    • Canadian Centre for Electron Microscopy and Brockhouse Institute for Materials Research, McMaster University

  • Shaobo Cheng

    • Canadian Centre for Electron Microscopy and Brockhouse Institute for Materials Research, McMaster University

  • Gianluigi Botton

    • Canadian Centre for Electron Microscopy and Brockhouse Institute for Materials Research, McMaster University

  • Christopher McMahon

    • Department of Physics and Astronomy, University of Waterloo

  • David G Hawthorn

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

  • Patrick Clancy

    • Department of Physics, University of Toronto

  • Sae Hwan Chun

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

  • Ambrose Seo

    • Department of Physics and Astronomy, University of Kentucky

  • Young-June Kim

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

  • John Y.T. Wei

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