Electron-Phonon Interactions for Optical Phonon Modes in Few-Layer Graphene

TL;DR

This study uses first-principles calculations to analyze how electron-phonon interactions affect optical phonon linewidths in few-layer graphene, revealing stacking-dependent variations and mode-specific coupling effects.

Contribution

It provides detailed insights into the electron-phonon coupling mechanisms and linewidth variations in multilayer graphene based on stacking and layer number.

Findings

Optical phonon modes in multilayer graphene show stacking-dependent frequency shifts.

Linewidths of certain modes decrease as the number of layers increases.

Interlayer coupling influences electron-phonon interaction strengths.

Abstract

We present a first-principles study of the electron-phonon (e-ph) interactions and their contributions to the linewidths for the optical phonon modes at $\Gamma$ and K in one to three-layer graphene. It is found that due to the interlayer coupling and the stacking geometry, the high-frequency optical phonon modes in few-layer graphene couple with different valence and conduction bands, giving rise to different e-ph interaction strengths for these modes. Some of the multilayer optical modes derived from the $\Gamma$-$E_{2g}$ mode of monolayer graphene exhibit slightly higher frequencies and much reduced linewidths. In addition, the linewidths of K-$A'_1$ related modes in multilayers depend on the stacking pattern and decrease with increasing layer numbers.