Stacking dependent optical properties of bilayer graphene

In this paper, the 1 + 1 layer folded graphene sheets that deviate from Bernal stacking are successfully fabricated and their electronic and optical structures are investigated by Raman and contrast spectroscopy. Significant blueshift of the single Lorentzian 2D band of folded graphene compared to that of single layer graphene (SLG) is observed, as shown in Fig. 1. This is attributed to SLG-like electronic structure of folded graphene but with slowing down of Fermi velocity. On the other hand, the stacking faults deviates from Bernal will break the translational symmetry of multilayer graphene and modify their electronic band structures and optical behaviors (both Raman [3] and optical conductivity [4]) to the extent depending on the interlayer coupling strength. While the optical conductivities of SLG and BLG with Bernal stacking are almost frequency-independent in the visible region, the optical conductivity of folded graphene is frequency-dependent, giving rise to additional absorption features due to the band folding effect.