Charge tuning of non-resonant magneto-exciton phonon interactions in graphene

TL;DR

This study investigates how the G-band phonon in graphene interacts with magneto-excitons under high magnetic fields, revealing non-resonant coupling effects modulated by carrier density and Landau level occupancy.

Contribution

It provides a detailed analysis of non-resonant electron-phonon interactions in graphene using high-field Raman scattering and a linearized interaction model, highlighting the role of Landau level filling.

Findings

Spectral features align with a linearized electron-phonon interaction model.

Splitting of the G-band phonon is due to circular dichroism caused by Landau level filling.

Piecewise linear slopes in spectra correspond to sequential Landau level occupancy.

Abstract

Far from resonance, the coupling of the G-band phonon to magneto-excitons in single layer graphene displays kinks and splittings versus filling factor that are well described by Pauli blocking and unblocking of inter- and intra- Landau level transitions. We explore the non-resonant electron-phonon coupling by high-magnetic field Raman scattering while electrostatic tuning of the carrier density controls the filling factor. We show qualitative and quantitative agreement between spectra and a linearized model of electron-phonon interactions in magnetic fields. The splitting is caused by dichroism of left and right handed circular polarized light due to lifting of the G-band phonon degeneracy, and the piecewise linear slopes are caused by the linear occupancy of sequential Landau levels versus $\nu$.