Chiral exciton in the topological insulator Bi$_2$Se$_3$

POSTER

Abstract

Materials with novel band structures can host ``chiral excitons'', where the exciton emission preserves the helicity of the excitation photon, as recently demonstrated in transition metal dichalcogenide monolayers~\footnote{H. Zeng, J. Dai, W. Yao, D. Xiao and X. Cui \textit{Nature Nanotech.} \textbf{7} 490} \footnote{K.F. Mak, K. He, J. Shan and T.F. Heinz \textit{Nature Nanotech.} \textbf{7} 494}. Here, we report the observation of a highly polarized photoluminescence peak, which is due to chiral exciton emission in the topological insulator Bi$_2$Se$_3$. Surprisingly, the energy of the emission is centered at 2.26\,eV, much higher than the 0.3\,eV bulk band gap of Bi$_2$Se$_3$. The excitation profile shows maximum polarization around 2.60\,eV excitation, suggesting the chiral exciton is due to interband transition between the topological surface states and a bulk band. We demonstrate that the polarization of the exciton emission is insensitive to temperature and Bi$_2$Se$_3$ film thickness, providing a convenient and robust platform for optoelectronic applications.

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Authors

  • Hsiang-Hsi Kung

    Rutgers University, Department of Physics \& Astronomy, Rutgers University

  • Maryam Salehi

    Rutgers University, Department of Physics \& Astronomy, Rutgers University

  • Xueyun Wang

    Department of Physics \& Astronomy, Rutgers University

  • Nikesh Koirala

    Rutgers U., Rutgers University, Department of Physics \& Astronomy, Rutgers University

  • matthew brahlek

    Pennsylvania State University, Department of Physics \& Astronomy, Rutgers University

  • Alexander Lee

    Rutgers University, Department of Physics \& Astronomy, Rutgers University

  • Sang-Wook Cheong

    Rutgers, The State University of New Jersey, Rutgers University, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA, RCEM, Rutgers Univ, Rutgers Univ, Department of Physics \& Astronomy, Rutgers University

  • Seongshik Oh

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

  • Girsh Blumberg

    Rutgers University, Department of Physics \& Astronomy, Rutgers University, Rutgers Univ