Photoemission study on a special type of multiferroics: GaV<sub>4</sub>S<sub>8</sub> &amp; GeV<sub>4</sub>S<sub>8</sub>

ORAL

Abstract

The lacunar spinels (AV4S8) with A=Ga and Ge, consisting of tetrahedral (AS4)n- and weakly linked cubane (V4S4)n+ are unique in known skyrmions because of a sizable ferroelectric polarization of ~ 1 μC/cm2 and polar crystal structure. Their electronic properties depend on the special degrees of freedom of the basic electronic units of V4S4. These materials are classified as a special class of Mott insulators in which strong electron correlations arise from weak intercluster hybridization. From the viewpoint of ionic formula, average valency of V is 3.25+ in GaV4S8 and 3+ in GeV4S8, yet exact valency of V in these compounds is not known. We conducted hard X-ray photoemission to study the electronic structure of GaV4S8 & GeV4S8 single crystals and to investigate the valency of V in these compounds. The V 2p photoemission spectra are best explained with (V4S4)5+ and (V4S4)6+ for GeV4S8 and GaV4S8 respectively. Further S 2p XPS spectra shows results consistent with the scenario of dynamical Jahn-Teller distortion in the paraelectric phase.

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Presenters

  • Amol Singh

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center

Authors

  • Amol Singh

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center

  • Jung-Han Li

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • Department of Physics, National Tsing-Hua University Taiwan

  • Yen-Fa Liao

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center

  • Hsiao-Yu Huang

    • National Synchrotron Radiation Research Center

  • Yen-Yi Chu

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center

  • Jing Chang

    • National Synchrotron Radiation Research Center

  • Ku-Ding Tsuei

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center

  • 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

  • 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

  • Michel A Van Veenendaal

    • Department of Physics, Northern Illinois University, DeKalb, IL 60115, USA

  • Di-Jing Huang

    • Condensed Matter Physics, National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center