Optical absorption window in Na${}_3$Bi based three-dimensional Dirac electronic system

Abstract

We present a detailed theoretical study of the optoelectronic properties of a Na${}_3$Bi-based three-dimensional Dirac electronic system (3DDES). The optical conductivity is evaluated using the energy-balance equation derived from a Boltzmann equation, where the electron Hamiltonian is taken from a simplified $\mathbf{k}\cdot \mathbf{p}$ approach. We find that for short-wavelength irradiation, the optical absorption in Na${}_3$Bi is mainly due to inter-band electronic transitions. In contrast to the universal optical conductance observed for graphene, the optical conductivity for Na${}_3$Bi based 3DDES depends on the radiation frequency but not on temperature, carrier density and electronic relaxation time. In the radiation wavelength regime of about 5 $\mu m<\lambda <$ 200 $\mu m$, an optical absorption window is found. This is similar to what is observed in graphene. The position and width of the absorption window depend on the direction of the light polarization and sensitively on temperature, carrier density, and electronic relaxation time. Particularly, we demonstrate that the inter-band optical absorption channel can be switched on and off by applying the gate voltage. This implies that similar to graphene, Na${}_3$Bi based 3DDES can also be applied in infrared electro-optical modulators. Our theoretical findings are helpful in gaining an in-depth understanding of the basic optoelectronic properties of recently discovered 3DDESs.

References in corpus (7)

• Electric Field Effect in Atomically Thin Carbon Films
• Universal dynamical conductance in graphite
• Optical far-infrared properties of graphene monolayer and multilayers
• Measurement of the Optical Absorption Spectra of Epitaxial Graphene from Terahertz to Visible
• Chiral anomaly and optical absorption in Weyl semimetals
• Optically Probing Spin and Charge Interactions in an Tunable Artificial Molecule
• Bulk crystal growth and electronic characterization of the 3D Dirac Semimetal Na3Bi