2014/04/28 by Martha Lasia, L. Brey, Luis Brey · 29 citations
Materials Science · Physics and Astronomy · #Condensed matter physics #Conductivity #Dirac fermion #Faraday effect #Graphene #Graphene research and applications #Kubo formula #Magnetic field #Optical conductivity #Optics #Physics #Quantum Mechanics and Non-Hermitian Physics #Quantum mechanics #Scattering #Topological Materials and Phenomena #Topological insulator #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.90.075417
published in Physical Review B 90(7) (American Physical Society) · 8 pages
arxiv created 2014/04/28 · openalex publication_date 2014/08/19 · arxiv updated 2015/06/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Starting from a three-dimensional Hamiltonian, we study the optical properties of ultrathin 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 comes 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 e2/h. This result implies large values of the Kerr rotation angle and a quantization of the Faraday angle. In ultrathin slabs, the absence of light multiple scattering and bulk conductivity makes the Kerr angle remain rather large in a wide range of frequencies.