Multiple magneto-phonon resonances in graphene

TL;DR

This study uncovers new magneto-phonon resonances in graphene involving K and Gamma phonons, including the first observation of resonant splitting of three crossing branches, emphasizing multi-phonon processes in hot carrier relaxation.

Contribution

It provides the first experimental observation and detailed theoretical analysis of multiple magneto-phonon resonances involving both K and Gamma phonons in graphene.

Findings

Observation of new magneto-phonon resonances involving K and Gamma phonons

First detection of resonant splitting of three crossing excitation branches

Highlighting the role of multi-phonon processes in hot carrier relaxation

Abstract

Our low-temperature magneto-Raman scattering measurements performed on graphene-like locations on the surface of bulk graphite reveal a new series of magneto-phonon resonances involving both K-point and Gamma-point phonons. In particular, we observe for the first time the resonant splitting of three crossing excitation branches. We give a detailed theoretical analysis of these new resonances. Our results highlight the role of combined excitations and the importance of multi-phonon processes (from both K and Gamma points) for the relaxation of hot carriers in graphene.