Filling-factor-dependent mangetophonon resonance in graphene.

We describe a peculiar fine structure acquired by the in-plane optical phonon at the point in graphene when it is brought into resonance with one of the inter-Landau-level transitions in this material. The effect is most pronounced when this lattice mode (associated with the G band in graphene Raman spectrum) is in resonance with inter-Landau-level transitions 0+, 1 and -,10, at a magnetic field B030 T. It can be used to measure the strength of the electron-phonon coupling directly, and its filling-factor dependence can be used experimentally to detect circularly polarized lattice vibrations