Photoemission study on a special type of multiferroics: GaV4S8 & GeV4S8

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