Electrodynamics of Graphene Literature Review

Question: Discuss about theElectrodynamics of Graphenefor Literature Review. Answer: Introduction Graphene is an isotope of carbon that has been produced in mass quantities only recently. It is considered to be one of the strongest natural materials and has been theorized to exist for almost a few centuries. Recently, some researchers have finally found some reliable methods to produce significant amounts of graphene. Graphene attracts huge amounts of interests from researchers as it exhibits unique properties (Bludov, Peres and Vasilevskiy, 2013). One of these unique properties is evident in the electrodynamic property of graphene in which it reflects electromagnetic radiation. This property of graphene is discussed in this assignment and a literature review has been conducted. Literature Review According to Lambin et al. (2016), the general techniques of electrodynamics can be used for analyzing and calculating the electromagnetic properties of graphene in spite of the fact that graphene has the properties different from any other material. The researchers also published an optimum number of molecular layers in the graphene structure for which, the GHz radiation absorption reaches a peak value. The researchers demonstrated an analytic method using rigorous coupled waves and numerical calculations for finding the amount of GHz radiation absorbed by the PMMA multilayer of a certain quantity of graphene. From their analysis, it has been shown that the absorption process is robust in nature and the defects in the graphene layer structure do not affect the absorption process in any way. However, the defects of the graphene layer do affect the electromagnetic properties of graphene and its behavior towards electromagnetic waves. Figure 1: Effects of Graphene Defects on Its EM Properties (Source: Lambin et al., 2016, pp. 18) In the above figure, the absorbance, reflectance and transmittance of a graphene multilayer has been denoted as A, R and T respectively and the value of N has been used as 6, 7 and 8 against the defect concentration at a frequency of 30 GHz. In the right part shown in the figure, the graphene structure covers multiple atomic planes and a fraction (denoted as f) of the graphene plane surface is covered by a number of separate islands. In their works, Bludov, Peres and Vasilevskiy (2013) mainly emphasized on single layer graphene instead of multiple layer. They considered one flat graphene sheet (single molecular layer) and located them in plane z=0 (such that the x-axis is perpendicular to this sheet. They also cladded the sheet with two semi-infinite dielectric materials having the dielectric permittivity e1 0 and a capping medium where e2 0. Now, they applied a uniform EM field along the y-axis. From this experiment, they found that the field is decomposed into two different waves having different polarization states. Hence, the authors published the results as the p-polarized (TM) waves were along the x and z-axis whereas the s-polarized (TE) waves were along the y-axis. Figure 2: Schematic Representation of p- and s-polarized Waves (Source: Bludov, Peres Vasilevskiy, 2013, pp. 2) The authors also came into conclusion that graphene exhibits significant optical properties under the effect of electromagnetic waves. When the phenomenon of total internal reflection of the electromagnetic waves occurs, the graphene layer absorbs the electromagnetic energy from the s-polarized waves. When the angle of incidence of the wave reaches the critical angle, the absorption also reaches its peak. Xu et al. (2012) based their research on a device named electro-optic modulator. Initially, they used silicon compounds for the device but this endeavor failed as the electro-optic properties of silicon are extremely poor. Then they switched to graphene as it shows significant electro-optic property due to the hexagonal arrangement of the lattice. Moreover, they said that intrinsic graphene material has zero band gap and hence, nano-electric operations can easily be done using this material. Using Kubo formalism and the Maxwell equations, the researchers successfully used graphene as an active medium for modulation of light transmission. They applied certain voltage to the graphene-oxide-silicon waveguide and found that the refractive indices showed significant variations. They used this particular property in order to electrically control the optical modulation in the GOS waveguide but also used different styles of electro-refraction and electro-absorption. According to Chen and Al (2011), graphene shows some unique properties of low-loss surface reactance against terahertz (THz) frequencies and far-infrared electromagnetic radiation. They used this unique property in order to tailor the surface induced by the radiation according to any required parameter. The researchers used the properties of high conductivity and tenability of graphene to produce the effects of scattering cancellation that were even better than the RF mantle cloaks used commonly. According to their research results, graphene consists of a two-dimensional electronic system and a single layer of atomic plane composed of carbon atoms. These carbon atoms are arranged in a hexagonal lattice form. Hence, the researchers described the graphene layer as a gapless semiconductor without any significant mass and a linear electron hole that has dispersion properties following the Fermi velocity vF = 108 cm/s. The researchers demonstrated some experimental methods by using electr omagnetic waves and numerical calculations for finding the amount of the electromagnetic radiation absorbed by a single graphene layer. From their analysis, it has been shown that the absorption process is robust in nature and the defects in the graphene layer structure do not affect the absorption process in any way. However, the defects of the graphene layer do affect the electromagnetic properties of graphene and its behavior towards electromagnetic waves. Conclusion Finally, it can be concluded graphene has unique properties and further research activities are needed to learn more about these properties. Graphene is considered as one of the hardest natural materials and it now finds use for a large number of purposes. According to the researches, the properties of graphene can be exploited and used in different industries and other similar sectors. Moreover, due to the extreme strength of the graphene material, it is extremely durable and can be used even at high temperatures. This literature review conducted in this assignment reflects the electrodynamic properties of graphene that have been known till now from the limited number of experiments conducted. References Bludov, Y. V., Peres, N. M., Vasilevskiy, M. I. (2013). Unusual reflection of electromagnetic radiation from a stack of graphene layers at oblique incidence.Journal of Optics,15(11), 114004. Chen, P. Y., Al, A. (2011). Atomically thin surface cloak using graphene monolayers.ACS nano,5(7), 5855-5863. Lambin, P., Lobet, M., Batrakov, K., Kuzhir, P. (2016). Electrodynamics of graphene/polymer multilayers in the GHz frequency domain. InFundamental and Applied Nano-Electromagnetics(pp. 45-67). Springer Netherlands. Xu, C., Jin, Y., Yang, L., Yang, J., Jiang, X. (2012). Characteristics of electro-refractive modulating based on Graphene-Oxide-Silicon waveguide.Optics express,20(20), 22398-22405.