Covalency-driven collapse of strong spin-orbit coupling in face-sharing iridium octahedra

ORAL

Abstract

We report ab-initio density functional theory calculation and Raman scattering results to explore the electronic structure of Ba5CuIr3O12 single crystals. This insulating iridate, consisting of face-sharing IrO6 octahedra forming quasi-one-dimensional chains, cannot be described by the local jeff = 1/2 moment picture commonly adopted for discussing electronic and magnetic properties of iridate compounds with IrO6 octahedra. The shorter Ir-Ir distance in the face-sharing geometry, compared to corner- or edge-sharing structures, leads to strong covalency between neighboring Ir. Then this strong covalency results in the formation of molecular orbitals (MO) at each Ir trimers as the low-energy electronic degree of freedom. The theoretically predicted three-peak structure in the joint density of states, a distinct indication of deviation from thejeff = 1/2 picture, is verified by observing the three-peak structure in the electronic excitation spectrum by Raman scattering.

*Supported by: Crystal growth (CJW): the National Research Foundation of Korea, Ministry of Science and ICT (No. 2016K1A4A4A01922028), Ab-initio DFT study (HSK, KH, DV) and crystal characterization (JWK, SWC): NSF DMR-1629059, Spectroscopy (MY, GB): NSF DMR-1709161. MY and HSK contributed equally to this work.

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Presenters

  • Mai Ye

    • Rutgers University, New Brunswick

Authors

  • Mai Ye

    • Rutgers University, New Brunswick

  • Heung Sik Kim

    • Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University

  • Jae-Wook Kim

    • Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, Rutgers University, New Jersey

  • Choong-Jae Won

    • Max Planck POSTECH/Korea Research Initiative, Pohang University of Science and Technology
    • Laboratory for Pohang Emergent Materials, Pohang Accelerator Laboratory and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology,

  • Kristjan Haule

    • Rutgers University, New Brunswick
    • Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, Rutgers University
    • Department of Physics, Rutgers University
    • Physics and Astronomy, Rutgers University, Piscataway, NJ, United States

  • David Vanderbilt

    • Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, Rutgers University, Piscataway, NJ-08854, USA
    • Physics and Astronomy, Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University, New Jersey
    • Rutgers University, USA
    • Rutgers Univ
    • Physics and Astronomy, Rutgers University, Piscataway, NJ, United States
    • Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA

  • Sang-Wook Cheong

    • Rutgers University
    • Department of Physics and Astronomy, Rutgers University
    • Rutgers University, New Brunswick
    • Rutgers Center for Emergent Materials and Department of Physics & Astronomy, Rutgers University
    • Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Department of Physics, Rutgers University
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ
    • Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
    • Physics, Rutgers University
    • Physics and Astronomy, Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University, New Jersey
    • Rutgers University, Physics and Astronomy, and Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science
    • RCEM, Department of Physics and Astronomy, Rutgers U.
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA, Rutgers Center for Emergent Materials

  • Girsh E Blumberg

    • Rutgers University, New Brunswick
    • Department of Physics, Rutgers University