Electrical switch to the resonant magneto-phonon effect in graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Graphene exhibits unique electronic properties influenced by magnetic fields.
• Electron-phonon coupling is fundamental to understanding material properties.
• Optical phonons play a key role in light-matter interactions.

Purpose of the Study:

• To investigate the electric-field tuning of resonant magneto-exciton optical phonon coupling in gated graphene.
• To explore the switching on and off of electron-phonon coupling via Fermi level manipulation.
• To analyze the impact of electronic excitation spectrum changes on optical phonon response.

Main Methods:

• Utilizing gated graphene structures subjected to high magnetic fields (B ~ 25 T).
• Employing polarization-resolved magneto-Raman scattering experiments.
• Tuning the Fermi level to control Landau level filling and Pauli blocking.

Main Results:

• Observed switching of electron-phonon coupling by tuning the Fermi level near magneto-phonon resonance.
• Detected splitting of phonon features with satellite peaks dependent on electronic excitation energy.
• Measured significant phonon energy shifts (±60 cm⁻¹) near resonance.
• Identified the role of cyclotron resonance in the phonon spectral evolution.

Conclusions:

• Electric field control of electron-phonon coupling in graphene is demonstrated.
• The Fermi level's position profoundly influences the electron-phonon interaction and optical phonon behavior.
• Magneto-Raman scattering is a powerful tool for probing these coupled phenomena.