Raman Linewidth Contributions from Four-Phonon and Electron-Phonon Interactions in Graphene

The Raman peak position and linewidth provide insight into phonon anharmonicity and electron-phonon interactions in materials. For monolayer graphene, prior first-principles calculations have yielded decreasing linewidth with increasing temperature, which is opposite to measurement results. Here, we explicitly consider four-phonon anharmonicity, phonon renormalization, and electron-phonon coupling, and find all to be important to successfully explain both the G peak frequency shift and linewidths in our suspended graphene sample over a wide temperature range. Four-phonon scattering contributes a prominent linewidth that increases with temperature, while temperature dependence from electron-phonon interactions is found to be reversed above a doping threshold (PLANCK CONSTANT OVER TWO PI omega(G)/2, with omega(G) being the frequency of the G phonon).

Automated summary

This study considers multiple factors such as phonon anharmonicity, phonon renormalization, and electron-phonon coupling on the Raman peak frequency shift and linewidth in graphene samples. The results show that four-phonon scattering contributes significantly to the linewidth, increasing with temperature, while the temperature dependence of electron-phonon interactions reverses above a certain doping threshold.