Optical conductivity and transparency in an effective model for graphene

Abstract

Motivated by experiments confirming that the optical transparency of graphene is defined through the fine structure constant and that it could be fully explained within the relativistic Dirac fermions in 2D picture, in this article we investigate how this property is affected by next-to-nearest neighbor coupling in the low-energy continuum description of graphene. A detailed calculation within the linear response regime allows us to conclude that, somewhat surprisingly, the zero-frequency limit of the optical conductivity that determines the transparency remains robust up to this correction.

Optical conductivity in an effective model for graphene: finite temperature corrections

“…It is seen from this result that the actual value of the conductivity at T = 0 is e 2 /(4 ), independent of frequency and the parameter m that captures the second nearest-neighbor interaction, in agreement with our previous calculation 27 and transparency experiments 3 . Interestingly though, there is however a hidden, non-analytic dependency through the domain of the stepwise function, that defines a region where the conductivity actually vanishes.…”

“…Along this article, we have discussed the effect of including the next-to-nearest neighbors hopping t , through the "mass" parameter m = ±2 2 /(9t a 2 ) in the dispersion relation 2 , on the optical conductivity of single-layer graphene. Our analysis is based on the continuum representation of the model via an effective field theory 27 , by extending our previous results at zero temperature 27 to the finite chemical potential and finte temperature scenario, Appendix A: Zero temperature limit of e σ11(ω, T ) Let us start from Eq. (III.21) (in natural units = 1), and consider the limit T → 0 (β → ∞), e σ 11 (ω, T = 0) = e 2 8 sgn(ω) sgn…”

Induced Brehemstrahlung by light in graphene

“…This rate has been verified under a number of experimental conditions [6]. On the other hand, many theoretical approaches have been used in the past to explain the rate of light absorption in graphene including quantum field theoretical methods [7][8][9][10][11][12]. It is interesting to point out that modeling graphene from a thin film to a monolayer can give different predictions of this rate [13].…”

Chemical sensing with graphene: A quantum field theory perspective

“…While providing an accurate prediction of the electronic structure for single adsorbed molecules 15 , ab-initio methods are not suitable to describe molecular concentrations, finite temperature and disorder effects. On the other hand, in complement with those numerical studies, the effects of molecular concentration, disorder and finite temperature can be described by analytical models based on the continuum Dirac approximation within quantum field theory 1,[16][17][18] , thus providing an intuitive and accurate 19 picture of the underlying physical phenomena. Moreover, with appropriate approximations, these analytical models can often provide explicit formulae that are useful to interpret actual experiments.…”

“…In this work, we present an analytical theory for the optical conductivity in graphene under a given concentration of adsorbed polar molecules. This theory is a direct application of our previous work 1,2 , based on a continuum description of graphene involving the effects of up to nextto-nearest neighbors on the underlying atomistic tightbinding Hamiltonian 20 , that is analyzed by means of quantum field theory methods to include the electrostatic effects of adsorbed polar molecules on the surface of graphene. We assume that the spatial distribution, as well as the orientation of the dipole moments are disordered.…”