Observation of magneto-phonon resonance of Dirac fermions in graphite

TL;DR

This paper reports the observation of magneto-phonon resonance in graphite, revealing strong coupling between Dirac fermion excitations and phonons, with implications for understanding electron-phonon interactions in layered carbon materials.

Contribution

It demonstrates the coherent coupling of Dirac fermion magneto-excitons with optical phonons in graphite, highlighting the conditions for sharp resonance and reduced carrier broadening.

Findings

Magneto-phonon resonance shows magnetic-field dependent mode splittings.

Sharp resonances occur in regions with properties similar to single-layer graphene.

Reduced carrier broadening below electron-phonon coupling constant explains resonance sharpness.

Abstract

Coherent coupling of Dirac fermion magneto-excitons with an optical phonon is observed in graphite as marked magnetic-field dependent splittings and anti-crossing behavior of the two coupled modes. The sharp magneto-phonon resonance occurs in regions of the graphite sample with properties of superior single-layer graphene having enhanced lifetimes of Dirac fermions. The greatly reduced carrier broadening to values below the graphene electron-phonon coupling constant explains the appearance of sharp resonances that reveal a fundamental interaction of Dirac fermions.