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Terahertz response of monolayer and few-layer WTe<sub>2</sub> at the nanoscale

ORAL

Abstract

Tungsten ditelluride (WTe2) is a transition metal dichalcogenide whose physical properties depend critically on the number of layers. We use apertureless scattering-type near-field optical microscopy operating at Terahertz (THz) frequencies and cryogenic temperatures to identify distinct THz range electromagnetic behavior of WTe2 mono-, bi- and tri-layer terraces in the same micro-crystals. We observed clear metallic behavior of the near-field signal on tri-layer regions. Our data are consistent with the existence of surface plasmon polaritons (SPP) in the THz range confined to tri-layer terraces in our specimens. The near-field signal on bi-layer regions surprisingly shows moderately metallicity, but with negligible temperature dependence. Subdiffractional THz imaging data together with theoretical calculations considering thermally activated carriers favor the semimetal scenario over the semiconductor scenario for bi-layer WTe2. THz images for monolayer terraces uncovered weakly insulating behavior consistent with transport data.

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Presenters

  • Ran Jing

    Columbia University, Columbia Univ

Authors

  • Ran Jing

    Columbia University, Columbia Univ

  • Yinming Shao

    Department of Physics, Columbia University, Columbia Univ, Columbia University

  • Zaiyao Fei

    Department of Physics, University of Washington, University of Washington

  • Chiu Fan Bowen Lo

    Columbia Univ, Columbia University

  • Francesco Ruta

    Department of Physics, Columbia University, Columbia University, Columbia Univ

  • John Staunton

    Columbia Univ

  • Alexander McLeod

    Columbia University, Department of Physics, Columbia University, Columbia Univ, Physics, Columbia University

  • Zhiyuan Sun

    Columbia Univ, Columbia University

  • Bor-Yuan Jiang

    Department of Physics, University of California, San Diego

  • Xinzhong Chen

    Department of Physics and Astronomy, State Univ of NY - Stony Brook, Department of Physics, Stony Brook University

  • Michael Fogler

    University of California, San Diego, Department of Physics, University of California San Diego, UC San Diego, Department of Physics, University of California, San Diego, UCSD, University of California San Diego

  • Mengkun Liu

    Stony Brook University, Department of Physics and Astronomy, State Univ of NY - Stony Brook, Department of Physics, Stony Brook University, Department of Physics and Astronomy, Stony Brook University

  • David Cobden

    Department of Physics, University of Washington, University of Washington

  • Xiaodong Xu

    Physics, University of Washington, Department of Physics, University of Washington, University of Washington, Department of Physics, University of Washington, Seattle, University of Washington, Seattle

  • Dimitri N Basov

    Columbia Univ, Columbia University