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Near-Room-Temperature Valence-Driven Spin-State/Metal-Insulator Transition in Strain-Tuned (Pr<sub>1-y</sub>Y<sub>y</sub>)<sub>1-x</sub>Ca<sub>x</sub>CoO<sub>3-δ </sub>Films

ORAL

Abstract

Pr-based cobaltites such as Pr1-xCaxCoO3-δ and (Pr1-yYy)1-xCaxCoO3-δ exhibit remarkable first-order coupled spin-state/metal-insulator/structural transitions driven by a unique Pr valence transition. Such phenomena offer highly appealing device functionality, but have thus far been confined to cryogenic temperatures in bulk materials. Here, we combine epitaxy on multiple substrates with transport, magnetometry, polarized neutron reflectometry, and temperature-dependent synchrotron X-ray diffraction and electron energy loss spectroscopy to demonstrate complete control over the electronic ground state of (Pr1-yYy)1-xCaxCoO3-δ films. Compressive strain realizes enhancement of the spin-state/metal-insulator transition to at least 245 K, with synchrotron diffraction and electron energy loss spectroscopy confirming a Pr/Co valence shift. Conversely, tensile strain stabilizes metallic ferromagnetism with Curie temperature up to 75 K. We thus construct a strain phase diagram, highlighting: (i) potential access to a unique quantum critical point, and (ii) that a room temperature strain-stabilized first-order spin-state/metal-insulator/structural/valence transition is likely within reach in such perovskites. 

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Publication: Planning to submit a manuscript in near future.

Presenters

  • Vipul Chaturvedi

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

Authors

  • Vipul Chaturvedi

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

  • Supriya Ghosh

    University of Minnesota

  • Patrick Quarterman

    National Institute of Standards and Tech

  • Purnima P Balakrishnan

    National Institute of Standards and Tech, National Institute of Standards and Technology

  • Brian J Kirby

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

  • Hua Zhou

    Argonne National Laboratory

  • Huikai Cheng

    Thermo Fisher Scientific

  • Amanda Huon

    Oak Ridge National Laboratory, University of the Sciences, University of the Sciences in Philadelphia

  • Timothy R Charlton

    Oak Ridge National Lab

  • Michael Fitzsimmons

    University of Tennessee; Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge National Lab

  • William M Postiglione

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

  • Andrew Jacobson

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

  • John E Dewey

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

  • Caroline Korostynski

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

  • Javier G Garcia Barriocanal

    University of Minnesota, University of Minnesota, USA, Characterization Facility, University of Minnesota

  • K. Andre Mkhoyan

    University of Minnesota

  • Chris Leighton

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