Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Role of electronic excitations in magneto-Raman spectra of graphene
AU - Kashuba, Oleksiy
AU - Falko, Vladimir
PY - 2012/10/16
Y1 - 2012/10/16
N2 - 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 (e-h) pairs, which belong to the irreducible representation A(2) of the point group C-6v of the graphene lattice, and are characterized by crossed polarization of incoming and outgoing photons. At high magnetic fields, this is manifested by the excitation of e-h inter-Landau-level (LL) transitions with selection rule n(-) -> n(+). Weaker Raman-active inter-LL modes also exist. One of those has a selection rule similar to the infrared absorption process, n(-) -> (n +/- 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 a strong magnetic field. The fine structure 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.
AB - 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 (e-h) pairs, which belong to the irreducible representation A(2) of the point group C-6v of the graphene lattice, and are characterized by crossed polarization of incoming and outgoing photons. At high magnetic fields, this is manifested by the excitation of e-h inter-Landau-level (LL) transitions with selection rule n(-) -> n(+). Weaker Raman-active inter-LL modes also exist. One of those has a selection rule similar to the infrared absorption process, n(-) -> (n +/- 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 a strong magnetic field. The fine structure 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.
KW - FIELD
KW - SPECTROSCOPY
KW - BILAYER GRAPHENE
KW - GRAPHITE
U2 - 10.1088/1367-2630/14/10/105016
DO - 10.1088/1367-2630/14/10/105016
M3 - Journal article
VL - 14
JO - New Journal of Physics
JF - New Journal of Physics
SN - 1367-2630
IS - 10
M1 - 105016
ER -