We examine the stacking order of multilayer graphene grown on the SiC(0001ˉ) surface using low-energy electron diffraction and surface X-ray diffraction. We show that the films contain a high density of rotational stacking faults caused by three types of rotated graphene: sheets rotated 30∘ and ±2.20∘ relative to the SiC substrate. These angles are unique because they correspond to commensurate phases of layered graphene, both with itself and with the SiC substrate. {\it Ab intio} calculations show that these rotational phases electronically decouple adjacent graphene layers. The band structure from graphene at fault boundaries displays linear energy dispersion at the K-point (Dirac cones), nearly identical to that of a single graphene sheet.
@article{arxiv.0706.2134,
title = {Rotational stacking and its electronic effects on graphene films grown on 4H-SiC$(000\bar{1})$},
author = {J. Hass and F. Varchon and J. E. Millan-Otoya and M. Sprinkle and W. A. de Heer and C. Berger and P. N. First and L. Magaud and E. H. Conrad},
journal= {arXiv preprint arXiv:0706.2134},
year = {2007}
}