Breit-Wigner-Fano lineshapes in Raman spectra of graphene

TL;DR

This paper explains the asymmetric Breit-Wigner-Fano lineshapes observed in graphene's Raman spectra as resulting from interference between phonon and electron-hole pair excitations, with theoretical results matching experiments.

Contribution

It provides a theoretical model for the Breit-Wigner-Fano lineshapes in graphene Raman spectra, linking the asymmetry to electron-hole interactions near the Dirac cone.

Findings

The BWF asymmetry factor varies with Fermi energy, showing a V-shaped dependence.

Theoretical calculations agree well with experimental data.

The asymmetry is due to interference between phonon and electron-hole excitation spectra.

Abstract

Excitation of electron-hole pairs in the vicinity of the Dirac cone by the Coulomb interaction gives rise to an asymmetric Breit-Wigner-Fano lineshape in the phonon Raman spectra in graphene. This asymmetric lineshape appears due to the interference effect between the phonon spectra and the electron-hole pair excitation spectra. The calculated Breit-Wigner-Fano asymmetric factor 1/qBWF as a function of the Fermi energy shows a V-shaped curve with a minimum value at the charge neutrality point and gives good agreement with the experimental result.