New Electromagnetic Mode in Graphene

A new, weakly damped, transverse electromagnetic mode is predicted in graphene. The mode frequency $\omega$ lies in the window $1.667<\hslash \omega /\mu <2$, where $\mu$ is the chemical potential, and can be tuned from radio waves to the infrared by changing the density of charge carriers through a gate voltage.

Figure 1

The dynamic conductivity of the graphene layer, in units $e^2{g}_s{g}_v/16\hslash$, as a function of the frequency $\Omega =\hslash \omega /\mu$ in the collisionless limit at zero temperature $T/\mu =0$. Imaginary and real parts of the intraband and interband contributions, as well as their sum (the total conductivity) are shown.

Figure 2

The value of $\sqrt{Q^2-{\Omega }^2}$ as a function of the dimensionless frequency $\Omega$ for the TE mode.

Figure 3

The real and imaginary parts of the dynamic conductivity of graphene, in units $e^2{g}_s{g}_v/16\hslash$, as a function of frequency $\Omega =\hslash \omega /\mu$ at finite temperatures.

Figure 4

The factor ${\tilde{\sigma }}^{\prime }(\omega )[-{\tilde{\sigma }}^{\prime \prime }(\omega )]$ from Eq. (9) as a function of $\Omega =\hslash \omega /\mu$ at finite temperatures.