Kinetic Equation Approach to Graphene in Strong External Fields

Abstract

The report presents the results of using the nonperturbative kinetic approach to describe the excitation of plasma oscillations in a graphene monolayer. As examples the constant electric field as well as an electric field of short high-frequency pulses are considered. The dependence of the induced conduction and polarization currents characteristics on the pulse intensity, pulse duration, and polarization is investigated. The characteristics of secondary electromagnetic radiation resulting from the alternating currents is investigated. The nonlinear response to the external electric field characterizes graphene as an active medium. Qualitative agreement is obtained with the existing experimental result of measurements of currents in constant electric fields and radiation from graphene in the case of excitation by means of the infrared and optical pulses.

Radiation Problems Accompanying Carrier Production by an Electric Field in the Graphene

“…We note that a transition to the quasiparticle representation in the model was used, for example, in Refs. [37,54,65,75]. Below, we follow the works by [54,65].…”

“…This field contributes to the effective quasiclassical electric field (1), which, in turn, has an effect on the dynamics of carriers according to Equation (27). The above formulation of the quantum kinetic theory describing excitations in the graphene [54,65] is constructed by analogy with the quantum kinetic theory describing the vacuum production of e − e + plasma (see, e.g., [46,76]).…”

“…Thus, at this stage, we study Equation (59) with CI (65) and (66), which do not contain the photon distribution function. We only take into account a spontaneous emission from the carrier currents produced by an external electric field.…”

“…In the graphene the excitation region is limited by a simply connected surface and it is not difficult to find the electromagnetic field in the whole space from surface currents [60]. A theoretical and experimental study of this kind of collective radiation was completed in References [61,62] within the framework of an alternative dynamic approach [63,64] and, in [54], to the KE approach [65]. In addition to the above mentioned quasiclassical radiation, a quantum component of the radiation also exists due to elementary acts of interaction of the carriers with photons.…”

“…The work is organized, as follows. In Section 2.1, we briefly describe (following in main References [54][55][56]65]) a nonperturbative KE approach for studying the evolution of carrier excitations in monolayer graphene under the action of an external quasiclassical time dependent electric field. The set of KE obtained here is an analog of the corresponding equations, which was used in strong field QED (see, e.g., [53]).…”