THz spectroscopy of ultralow carrier density topological insulator thin films

ORAL

Abstract

Sb2Te3 is one of the earliest known examples of a 3D topological insulator with a single Dirac cone on the surface. Pure Sb2Te3 is generally p-doped with the Fermi level embedded in the bulk valence band which makes it challenging to study surface state dynamics through transport and optical measurements. Only recently, bulk insulating Sb2Te3 thin films have been grown using molecular beam epitaxy via chemical doping and buffer layer engineering. In addition, the carrier densities in these films are exceptionally low, nearly an order of magnitude lower than the best results obtained in Bi2Se3. Here we report the magneto-optical response of regular and bulk insulating (p-type and n-type) Sb2Te3 films at THz frequencies using time-domain polarimetry. While undoped, bulk conducting samples exhibit usual semiclassical behaviour, the bulk insulating samples show unusual optical properties and quantized response in presence of magnetic fields.

–

Presenters

  • Dipanjan Chaudhuri

    Johns Hopkins University

Authors

  • Dipanjan Chaudhuri

    Johns Hopkins University

  • Maryam Salehi

    Rutgers, the State University of New Jersey, Materials Science and Engineering, Rutgers, The State University of New Jersey, Materials Sci. & Eng., Rutgers University, Rutgers University, New Brunswick, Rutgers University, Rutgers University - New Brunswick

  • Mintu Mondal

    Johns Hopkins University

  • Jisoo Moon

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

  • Deepti Jain

    Rutgers, the State University of New Jersey, Physics, Rutgers University, Rutgers University, New Brunswick, Rutgers University

  • Seongshik Oh

    Rutgers, the State University of New Jersey, Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Physics and Astronomy, Rutgers, The State University of New Jersey, Physics, Rutgers University, Physics, Rutgers, The State University of New Jersey, Rutgers University, Rutgers University - New Brunswick

  • Peter Armitage

    Johns Hopkins University, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, United States, Department of Physics and Astronomy, Johns Hopkins University