1301.3795 (J. Campos-Delgado et al.)

Raman-scattering study of the phonon dispersion in twisted bi-layer
graphene    [PDF]

J. Campos-Delgado, L. G. Cançado, C. A. Achete, A. Jorio, J. -P. Raskin

Bi-layer graphene with a twist angle \theta\ between the layers generates a superlattice structure known as Moir\'{e} pattern. This superlattice provides a \theta-dependent q wavevector that activates phonons in the interior of the Brillouin zone. Here we show that this superlattice-induced Raman scattering can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG). The effect reported here is different from the broadly studied double-resonance in graphene-related materials in many aspects, and despite the absence of stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are observed.

View original: http://arxiv.org/abs/1301.3795