The Origin of Ising Magnetism in Ca<sub>3</sub>Co<sub>2</sub>O<sub>6</sub> Unveiled by Orbital Imaging

ORAL

Abstract


One-dimensional CoO6 chains in Ca3Co2O6 arranged in a triangular lattice give rise to an Ising-like magnetism with an intriguing quantum tunneling staircase structure in its magnetization. To resolve the underlying local electronic configuration of the Co ions we applied s-core-level non-resonant inelastic x-ray scattering (s-NIXS), a new technique that is capable of imaging the shape of the 3d orbitals in real space. The orbital shapes that we found established unequivocally that both Co sites (octahedral and trigonal prismatic) are in a 3+ valence state (i.e. 3d6); the trigonal Co site has a high-spin configuration while the octahedral Co site is low spin. Interestingly, we directly ‘see’ that it is the complex d2 orbital that is stabilized by the prismatic trigonal coordination, which naturally explains the Ising magnetism in the system. Utilizing this ability to image electron orbitals, and thus directly relating the orbital occupation with the local crystal structure—without the need for theoretical modeling—is essential for modeling magnetic properties. This is especially true in situations where one would like to make use of the delicate balance of competing interactions to stabilize a particular orbital state for a desired or optimized physical property.

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Presenters

  • Brett Leedahl

    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids

Authors

  • Brett Leedahl

    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids

  • Martin Sundermann

    • Institute of Physics II, University of Cologne
    • Physics 2, University of Cologne, Germany
    • Max Planck Institute for Chemical Physics of Solids

  • Andrea Amorese

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Andrea Severing

    • Institute of Physics II, University of Cologne
    • Physics 2, University of Cologne, Germany
    • University of Cologne

  • Hlynur Gretarsson

    • DESY, Hamburg, Germany
    • Deutsches Elektronen-Synchrotron (DESY)

  • Lunyong Zhang

    • Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
    • Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
    • Max Planck Institute for Chemical Physics of Solids

  • Alexander Komarek

    • Max Planck Institute
    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

  • Antoine Maignan

    • Laboratoire CRISMAT

  • Maurits Haverkort

    • Institute for Theoretical Physics, Heidelberg University
    • Institute for theoretical physics
    • Institute of Theoretical Physics, University of Heidelberg
    • Theoretical Physics, Heidelberg University, Germany
    • Heidelberg University

  • Liu Tjeng

    • Max Planck Inst
    • Max-Planck Institute for Chemical Physics of Solids Dresden
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids