Role of electronic excitations in magneto-Raman spectra of graphene

Oleksiy Kashuba; Vladimir I. Fal'ko

doi:10.1088/1367-2630/14/10/105016

paper

Role of electronic excitations in magneto-Raman spectra of graphene

arXiv:1212.2389 · doi:10.1088/1367-2630/14/10/105016

Abstract

We investigate the signature of the low-energy electronic excitations in the Raman spectrum of monolayer and bilayer graphenes. The dominant contribution to the Raman spectra is due to the interband electron-hole pairs, which belong to the irreducible representation A $_{2}$ of the point group C $_{6 v}$ of the graphene lattice, and are characterised by crossed polarisation of incoming and outgoing photons. At high magnetic fields, this is manifested by the excitation of electron-hole (e-h) inter-Landau-level transitions with selection rule $n^{-} \to n^{+}$ . Weaker Raman-active inter-Landau-level modes also exist. One of those has a selection rule similar to the infrared absorption process, $n^{-} \to (n \pm 1)^{+}$ , but the created e-h excitation belongs to the irreducible representation E $_{2}$ (rather than E $_{1}$ ) and couples to the optical phonon mode, thus undergoing an anticrossing with the optical phonon G-line in Raman in strong magnetic field. The fine structure of acquired by the G-line due to such anticrossing depends on the carrier density, inhomogeneity of doping, and presence of inhomogeneous strain in the sample.

21 pages, 6 figures

Role of electronic excitations in magneto-Raman spectra of graphene

Abstract

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