Emergence of charge density waves and a pseudogap in single-layer TiTe<sub>2</sub>

ORAL

Abstract

Two-dimensional materials constitute a promising platform for developing nanoscale devices and systems. Their physical properties can be very different from those of the corresponding three-dimensional materials because of extreme quantum confinement and dimensional reduction. Here we report a study of TiTe2 from the single-layer to the bulk limit. Using angle-resolved photoemission spectroscopy and scanning tunneling microscopy and spectroscopy, we observed the emergence of a (2 × 2) charge density wave order in single-layer TiTe2 with a transition temperature of 92 ± 3 K. Also observed was a pseudogap of about 28 meV at the Fermi level at 4.2 K. Surprisingly, no charge density wave transitions were observed in two- and multi-layer TiTe2, despite the quasi-two-dimensional nature of the material in the bulk. The unique charge density wave phenomenon in the single layer raises intriguing questions that challenge the prevailing thinking about the mechanisms of charge density wave formation.

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Presenters

  • Peng Chen

    • Department of Physics, University of Illinois Urbana-Champaign

Authors

  • Peng Chen

    • Department of Physics, University of Illinois Urbana-Champaign

  • Woei Wu Pai

    • Center for Condensed Matter Sciences, National Taiwan University

  • Yang-hao Chan

    • Institute of Atomic and Molecular Sciences, Academia Sinica
    • Department of Physics, UC Berkeley
    • Inst of Atomic and Molecular Sciences, Academia Sinica
    • Institute of Physics Academia, Sinica

  • A Takayama

    • Department of Physics, University of Tokyo

  • Caizhi Xu

    • Department of Physics, University of Illinois Urbana-Champaign
    • Department of Physics, Univ of Illinois - Urbana

  • A. Karn

    • Center for Condensed Matter Sciences, National Taiwan University

  • S. Hasegawa

    • Department of Physics, University of Tokyo

  • Mei-Yin Chou

    • Institute of Atomic and Molecular Sciences, Academia Sinica

  • Sung-Kwan Mo

    • Lawrence Berkeley National Lab
    • Lawrence Berkeley Natl Lab
    • Lawrence Berkeley National Laboratory
    • Pohang Accelerator Laboratory
    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Alexei Fedorov

    • Lawrence Berkeley Natl Lab
    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Tai-Chang Chiang

    • Department of Physics, University of Illinois Urbana-Champaign
    • Univ of Illinois - Urbana
    • physics, Univ of Illinois - Urbana
    • Univeristy of Illinois
    • Department of Physics, Univ of Illinois - Urbana