Abstract:
We discuss optical absorption in topological insulators and study
possible photoelectric effects theoretically. We found that absorption of
circularly polarized electromagnetic waves in two-dimensional topological
insulators results in electric current in the conducting $1D$ edge channels,
the direction of the current being determined by the light polarization. We
suggest two ways of inducing such a current: due to magnetic dipole electron
transitions stimulated by irradiation of frequency below the bulk energy
gap, and due to electric dipole transitions in the bulk at frequencies larger
than the energy gap with subsequent capture of the photogenerated carriers on
conducting edge states.
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