Unusual Microwave Response of Dirac Quasiparticles in Graphene

V. P. Gusynin; S. G. Sharapov; J. P. Carbotte

doi:10.1103/PhysRevLett.96.256802

paper

Unusual Microwave Response of Dirac Quasiparticles in Graphene

arXiv:cond-mat/0603267 · doi:10.1103/PhysRevLett.96.256802

Abstract

Recent experiments have proven that the quasiparticles in graphene obey a Dirac equation. Here we show that microwaves are an excellent probe of their unusual dynamics. When the chemical potential is small the intraband response can exhibit a cusp around zero frequency $Ω$ and this unusual lineshape changes to Drude-like by increasing the chemical potential $∣ μ ∣$ , with width also increasing linearly with $μ$ . The interband contribution at T=0 is a constant independent of $Ω$ with a lower cutoff at $2 μ$ . Distinctly different behavior occurs if interaction-induced phenomena in graphene cause an opening of a gap $Δ$ . At large magnetic field $B$ , the diagonal and Hall conductivities at small $Ω$ become independent of $B$ but remain nonzero and show structure associated with the lowest Landau level. This occurs because in the Dirac theory the energy of this level, $E_{0} = \pm Δ$ , is field independent in sharp contrast to the conventional case.

arXiv comment4 pages, RevTeX4, 4 EPS figures

Unusual Microwave Response of Dirac Quasiparticles in Graphene

Abstract

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