Magnetopolaritons in Weyl Semimetals in a Strong Magnetic Field

Exotic topological and transport properties of Weyl semimetals have generated a lot of excitement in the condensed matter community. Here we show that Weyl semimetals in a strong magnetic field are highly unusual optical materials. The propagation of electromagnetic waves is affected by an interplay between the plasmonic response of chiral Weyl fermions and extreme anisotropy induced by a magnetic field. The resulting magnetopolaritons possess a number of peculiar properties, such as hyperbolic dispersion, photonic stop bands, coupling-induced transparency, and broadband polarization conversion. These effects can be used for optical spectroscopy of these materials including detection of the chiral anomaly or for broadband terahertz or infrared applications.

Figure 1

Dispersion [real part of $\mu (\omega )$] of the extraordinary waves in a magnetic field of 10 T for several different propagation angles $\theta$.

Figure 2

Absorption spectrum for LHC (solid line) and RHC (dashed line) polarizations in a magnetic field $B=10\mathrm{T}$ at zero temperature, the Fermi energy of 60 meV, and the relaxation constant $\gamma =1\mathrm{meV}$.

Figure 3

Absorption spectrum before (solid line) and after (dashed line) a constant electric field $\mathit{E}\parallel \mathit{B}$ is applied, which shifts the Fermi levels by $\pm 30\mathrm{meV}$ in the two Weyl nodes. The magnetic field is 10 T and the relaxation constant $\gamma =1\mathrm{meV}$.