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Temperature- and layer- dependent spin-orbit coupling in atom-thick transition metal dichalcogenides

ORAL

Abstract

Atomically thin semiconducting transition metal dichalcogenides (TMDs) are emerging as a new platform for exploring two-dimensional exciton physics. These excitons play a crucial role in determining the light-matter interactions of a semiconducting material. Understanding the origin of valence band splitting is important because it governs the unique spin and valley physics in TMDs. We have explored the effects of temperature and number of layers on spin−orbit coupling (SOC) in MoS2 and WS2 (monolayers to 6 Layers and bulk~100 layers) by determining the difference between A and B excitonic peak energy (Δ=EB-EA) in photocurrent spectra at different temperatures from 77 K to 300 K. We have found few important characteristics of the SOC coupling. First, MoS2 and WS2 demonstrate very different temperature-dependent SOC behavior. Second, SOC strength is the lowest for monolayer. Third, coupling increases as we increase the layer thickness. Third, the rate of change of the coupling strength with respect to temperature (m=δΔ/δT) depends on the layer thickness for MoS2. Our study sheds light on the distinctive behaviors about SOC coupling in layered MoS2 and WS2.

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Presenters

  • Akm Newaz

    Department of Physics and Astronomy, San Francisco State University, Physics and Astronomy, San Francisco State University, San Francisco State University, Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132, United States

Authors

  • Akm Newaz

    Department of Physics and Astronomy, San Francisco State University, Physics and Astronomy, San Francisco State University, San Francisco State University, Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132, United States

  • Garrett Benson

    Physics and Astronomy, San Francisco State University

  • Viviane Z. Costa

    Department of Physics and Astronomy, San Francisco State University, Physics and Astronomy, San Francisco State University, San Francisco State University, Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132, United States

  • Shirin Jamali

    Department of Physics and Astronomy, San Francisco State University, Physics and Astronomy, San Francisco State University, Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132, United States

  • Kentaro Yumigeta

    Materials Science and Engineering, Arizona State University

  • Mark Blei Blei

    Arizona State University, Materials Science and Engineering, Arizona State University

  • Sefaattin Tongay

    Arizona State Univ, Arizona State University, Materials Science and Engineering, Arizona State University

  • Bin Wang

    Chemical, Biological & Materials Engineering, University of Oklahoma

  • Santosh KC

    San Jose State University, Materials Engineering, San Jose State University

  • Andrew Ichimura

    Department of Chemistry and Biochemistry, San Francisco State University, Chemistry and Biochemistry, San Francisco State University, Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132, United States