Dielectric response and novel electromagnetic modes in three-dimensional Dirac semimetal films

TL;DR

This paper investigates the electromagnetic properties of three-dimensional Dirac semimetal films, revealing their ability to support surface plasmons and novel dielectric modes, with potential applications in mid-infrared photonics and tunable devices.

Contribution

It introduces the prediction of novel electromagnetic modes in 3D Dirac semimetal films and demonstrates their tunability for photonic applications.

Findings

Existence of surface-plasmon polaritons at low frequencies

Presence of dielectric waveguide modes at higher frequencies

Wide-angle mid-IR passband enabling omnidirectional filtering

Abstract

Using the Kubo formalism we have calculated the local dynamic conductivity of a bulk, i.e., three-dimensional (3D), Dirac semimetal (BDS). We obtain that at frequencies lower than Fermi energy the metallic response in a BDS film manifests in the existence of surface-plasmon polaritons, but at higher frequencies the dielectric response is dominated and it occurs that a BDS film behaves as a dielectric waveguide. At this dielectric regime we predict the existence inside a BDS film of novel electromagnetic modes, a 3D analog of the transverse electric waves in graphene. We also find that the dielectric response manifests as the wide-angle passband in the mid-infrared (IR) transmission spectrum of light incident on a BDS film, which can be used for the interferenceless omnidirectional mid-IR filtering. The tuning of the Fermi level of the system allows us to switch between the metallic and the dielectric regimes and to change the frequency range of the predicted modes. This makes BDSs promising materials for photonics and plasmonics.