Energy Dependence of the Photogalvanic Effect in a Bi2Se3 Nanoflake Device

ORAL

Abstract

Bi2Se3 is a prototypical topological insulator exhibiting gapped bulk states with topologically protected conducting surface states. Here we study the linear photogalvanic effect (LPGE) in a Bi2Se3 nanoflake device as a function of energy from 0.3 to 1.8 eV. At 800 nm (1.5 eV) with the laser polarized parallel to the current, we measure a positive or negative response when the laser excitation is close to one of the contacts. Fixing the laser at the peak response, we measuring the energy dependence of the LPGE as we scan from 0.3 eV to 1.8 eV. Peaks are seen at 0.35 eV, and other higher lying optical transitions. We modulate the 800 nm excitation laser between left and right circularly polarized light observing, when current flows, positive and negative peaks at the edge of the nanosheet in line scans, consistent with a spin-Hall effect.

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Presenters

  • Seyyedesadaf Pournia

    Department of Physics, University of Cincinnati

Authors

  • Seyyedesadaf Pournia

    Department of Physics, University of Cincinnati

  • Giriraj Jnawali

    Department of Physics, University of Cincinnati

  • Howard E Jackson

    Department of Physics, University of Cincinnati

  • Leigh Smith

    Department of Physics, University of Cincinnati, Physics, University of Cincinnati

  • Ryan Need

    National Institute of Standards and Technology, Materials Department, University of California, Santa Barbara, NIST Center for Neutron Research, National Institute for Standards and Technology

  • Stephen Wilson

    University of California, Santa Barbara, Materials Department, University of California, Santa Barbara, Materials, University of California Santa Barbara, Materials, University of California, Santa Barbara, UC Santa Barbara