Observation of Dirac Band Splitting in a Peierls Semimetal (TaSe4)2I

ORAL

Abstract

(TaSe4)2I shows a characteristic metal-insulator phase transition by decreasing temperature. Above the charge density wave (CDW) temperature Tc, (TaSe4)2I has been predicted to be a Weyl semimetal phase. Below Tc, it becomes an axion insulator phase. Here, we performed the angle-resolved photoemission spectroscopy (ARPES) measurements on the (110) surface of (TaSe4)2I and observed two sets of Dirac-cone-shaped bands. Our first-principles calculations show that each Dirac band is composed of two overlapped Weyl bands. Moreover, we found that each Dirac band exhibits tens of meV energy splitting. By the combination of our theoretical calculations and core level measurements, we demonstrated that the Dirac band splitting is a result of the loss of the iodine anion on the cleaved (110) surface. Our ARPES results further show that the iodine loss-induced Dirac band splitting can be altered by temperature. Our findings shed light on the interplay between band topology and CDW order in a Peierls semimetal and will motivate more studies on these strongly correlated topological condensed matter systems.

*This work is supported by NSF-CAREER award (DMR-1847811), DOE grant (DE-SC0019064), and the Gordon and Betty Moore Foundation’s EPiQS Initiative (Grant GBMF9063 to C. Z. C.).

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Presenters

  • Hemian Yi

    • Pennsylvania State University
    • Department of Physics, Pennsylvania State University

Authors

  • Hemian Yi

    • Pennsylvania State University
    • Department of Physics, Pennsylvania State University

  • Lujin Min

    • Department of Material Science and Engineering, Penn State University
    • Department of Physics, Pennsylvania State University
    • Physics, Pennsylvania State University
    • Pennsylvania State University
    • Department of Materials Science and Engineering, Pennsylvania State University

  • Zengle Huang

    • Department of Physics and Astronomy, Rutgers, The State University of New Jersey
    • Rutgers University

  • Rui Wu

    • Beijing Academy of Quantum Information Sciences

  • Ruoxi Zhang

    • Pennsylvania State University

  • Yifan Zhao

    • Pennsylvania State University
    • Department of Physics, Pennsylvania State University

  • Ling-Jie Zhou

    • Pennsylvania State University

  • Moses H W Chan

    • Pennsylvania State University
    • Department of Physics, The Pennsylvania State University

  • Weiwei Xie

    • Louisiana State University, Department of Chemistry
    • Department of Chemistry and Chemical Biology, Rutgers University , Rutgers University, Piscataway, NJ08854, USA
    • Rutgers University, New Brunswick
    • Rutgers, The State University of New Jersey
    • Louisiana State University
    • Rutgers University

  • Weida Wu

    • Rutgers Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
    • Department of Physics and Astronomy, Rutgers, The State University of New Jersey
    • Rutgers University
    • Department of Physics and Astronomy, Rutgers University

  • Zhiqiang Mao

    • Pennsylvania State University
    • Department of Physics, Penn State University
    • The Pennsylvania State University
    • Penn State University
    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Physics, Pennsylvania State University
    • Department of Materials Science and Engineering, Pennsylvania State University

  • Zhijun Wang

    • Princeton University, Department of Physics
    • Chinese Academy of Sciences, Institute of Physics
    • Institute of Physics, Chinese Academy of Sciences
    • Chinese Academy of Sciences,Institute of Physics

  • Cui-Zu Chang

    • Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Department of Physics, Pennsylvania State University
    • The Pennsylvania State University