Energy- and Momentum-Resolved Characterization of Optical Transitions in Bi2Se3

ORAL

Abstract

Light-matter interactions are at the heart of many physical phenomena including photocurrents in the topological insulator Bi2Se3. However, it is not clear whether these photocurrents stem from topological surface states or bulk bands. Time- and angle-resolved photoemission spectroscopy is used to probe the structure and dynamics of photocurrents in unoccupied electronic states of Bi2Se3. Here we demonstrate the use of a “time mapping” analysis to measure which initial states below the Fermi level couple to which unoccupied states via optical excitations, in a band-resolved manner. We measure the time following optical excitation for unoccupied states to reach maximum population as a function of energy and momentum; faster rise times indicate direct excitation from initial occupied states. Time mapping analysis displays promise for improving our understanding of optoelectronic effects including photocurrent generation.

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Presenters

  • Alexandre Gauthier

    Stanford University and SLAC National Accelerator Laboratory, Stanford University

Authors

  • Alexandre Gauthier

    Stanford University and SLAC National Accelerator Laboratory, Stanford University

  • Hadas Soifer

    Stanford University

  • Costel Rotundu

    Stanford University

  • Alexander Kemper

    North Carolina State University, North Carolina State Univ, Physics, North Carolina State University, Dept of Physics, North Carolina State Univ

  • Shuolong Yang

    Cornell Univ, Kavli Institute at Cornell for Nanoscale Science, Cornell University, Stanford University

  • Hongyu Xiong

    Stanford University, Stanford Univ

  • Makoto Hashimoto

    SLAC, SLAC, Stanford University, SLAC National Laboratory, Stanford University, SLAC - Natl Accelerator Lab, SLAC National Accelerator Laboratory, SSRL, SLAC

  • Donghui Lu

    SSRL/SLAC, SLAC, SLAC, Stanford University, SLAC National Laboratory, Stanford University, SLAC - Natl Accelerator Lab, SLAC National Accelerator Laboratory, SSRL, SLAC

  • Patrick Kirchmann

    SLAC National Accelerator Laboratory, Stanford University

  • Jonathan Sobota

    Stanford University and SLAC National Accelerator Laboratory, Stanford University, Stanford Univ

  • Zhi-Xun Shen

    Stanford University, SLAC National Accelerator Laboratory, SLAC - Natl Accelerator Lab, Stanford Univ, SIMIS, Stanford University, Applied Physics, Stanford Univ, Stanford University and SLAC National Accelerator Laboratory, Applied Physics, Stanford University