Influence of Magnetic Field and Temperature on Half Width at Half Maximum of Multi-photon Absorption Spectrum in Two-dimensional Graphene

TL;DR

This study theoretically investigates how magnetic field and temperature affect the spectral line width of multi-photon absorption in 2D graphene, revealing a square root dependence on magnetic field and independence from temperature.

Contribution

It provides a novel theoretical analysis of the HWHM of multi-photon absorption peaks in graphene considering magnetic and thermal effects, aligning with experimental data.

Findings

HWHM increases with magnetic field as sqrt(B)

HWHM is independent of temperature

Multi-photon absorption peaks are enhanced by stronger magnetic fields and electromagnetic waves

Abstract

We use the Profile numerical method to calculate the spectral line width, or half width at half maximum (HWHM) of the absorption peaks of multi-photon absorption processes in a two-dimensional graphene system (2DGS) according to important external parameters such as magnetic field and temperature in the presence of strong electromagnetic waves (SEMW). The appearance of these absorption peaks is theoretically obtained from magneto-phonon resonance conditions within the framework of the quantum kinetic equation. The results take into account both scattering mechanisms: electron-optical phonon and electron-acoustic phonon. Under the influence of the magnetic field, according to the increasing photon energy of the SEMW, the graph showing the dependence of the multi-photon nonlinear absorption coefficient on photon energy has the form of absorption spectrum lines following magneto-phonon resonance conditions. When increasing the value of the external magnetic field and the intensity of the SEMW, the intensity of the resonance peaks increases. In addition, the HWHM W of the resonance peaks of multi-photon absorption processes increases with increasing magnetic field $\mathrm{B}$ according to the square root law $\mathrm{W} = \kappa\sqrt{\mathrm{B}}$ but is independent of temperature. The value of the HWHM of the one-photon absorption process is larger than the value of the HWHM of the multi-photon absorption processes. The calculations of the HWHM of the one-photon absorption process in this paper are consistent with previous experimental observations and theoretical calculations. Thus, our calculations of the HWHM of multi-photon absorption processes can serve as reliable predictions for future experiments.