Intrinsic optical conductivity of a symmetric topological insulator

Abstract

In this work we analytically investigate the longitudinal optical conductivity of the symmetric topological insulator. The conductivity expressions at T = 0 are derived using the Kubo formula and expressed as a function of the ratio of the Dresselhaus and Rashba parameters that characterize the low-energy Hamiltonian. We find that the longitudinal inter-band conductivity vanishes when Dresselhaus and Rashba parameters are equal in strength, also called the persistent spin helix state. The calculations are extended to obtain the frequency-dependent real and imaginary components of the optical conductivity for the topological Kondo insulator SmB6 which exhibits symmetric and anisotropic Dirac cones hosting topological states at point on the surface Brillouin zone.