Electron-mediated anharmonicity and its role in the Raman spectrum of graphene

TL;DR

This paper investigates how electron interactions influence the anharmonicity and Raman spectrum of graphene, providing a comprehensive model that explains temperature-dependent spectral features.

Contribution

It introduces a unified approach to account for electron-phonon coupling, phonon-phonon interactions, and anharmonicity in calculating graphene's Raman spectrum.

Findings

Successfully explains the temperature dependence of G mode frequency and linewidth.

Demonstrates the importance of electron-mediated phonon interactions in spectral features.

Provides a broadly applicable method for studying phonon dynamics in materials.

Abstract

The Raman active G mode in graphene exhibits strong coupling to electrons, yet the comprehensive treatment of this interaction in the calculation of its temperature-dependent Raman spectrum remains incomplete. In this study, we calculate the temperature dependence of the G mode frequency and linewidth, and successfully explain the experimental trend, by accounting for the contributions arising from the first-order electron-phonon coupling, electron-mediated phonon-phonon coupling, and standard lattice anharmonicity. The generality of our approach enables its broad applicability to study phonon dynamics in materials where both electron-phonon coupling and anharmonicity are important.