Raman spectroscopy study of rotated double-layer graphene:   Misorientation-angle dependence of electronic structure
  We present a systematic Raman study of unconventionally-stacked double-layer graphene, and find that the spectrum strongly depends on the relative rotation angle between layers. Rotation-dependent trends in the position, width and intensity of graphene 2D and G peaks are experimentally established and accounted for theoretically. Our theoretical analysis reveals that changes in electronic band structure due to the interlayer interaction, such as rotational-angle dependent Van Hove singularities, are responsible for the observed spectra features. Our combined experimental and theoretical study provides a deeper understanding of the electronic band structure of rotated double-layer graphene, and leads to a practical way to identify and analyze rotation angles of misoriented double-layer graphene. 
Kwanpyo Kim, Sinisa Coh, Liang Z. Tan, William Regan, Jong Min Yuk,   Eric Chatterjee, M. F. Crommie, Marvin L. Cohen, Steve...
cond-mat.mes-hall