Optical properties of magnetically doped ultra-thin topological insulator slabs

Abstract

Starting from a three dimensional Hamiltonian, we study the optical properties of ultra-thin topological insulator slabs for which the coupling between Dirac fermions on opposite surfaces results in two degenerated gapped hyperbolic bands. The gap is a threshold for the optical absorption and translates in a peak in the imaginary part of the optical conductivity. An exchange field applied perpendicular to the slab splits the degenerated hyperbolic bands and a double step structure come out in the optical absorption, whereas a double peak structure appears in the imaginary part of the longitudinal optical conductivity. The exchange field breaks time-reversal symmetry and for exchange fields larger than the surfaces coupling gap, the zero frequency Hall conductivity is quantized to $e^2/h$. This result implies large values of the Kerr and Faraday rotation angles. In ultra-thin slabs, the absence of light multiple scattering and bulk conductivity, makes the Kerr and Faradays angles to remain rather large in a wide range of frequencies.

8 pages

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Cited by in corpus (5)

• Magneto-optical transport properties of monolayer WSe2
• Off-resonant polarized light-controlled thermoelectric transport in ultrathin topological insulators
• Optical Conductivity of Topological Insulator Thin Films in a Quantizing Magnetic Field
• Unconventional quantum Hall effect in Floquet topological insulators
• Thermal-Field Electron Emission from Three-Dimensional Topological Semimetals