Detection of Interlayer Interaction in Few-layer Graphene through Landau   Level Spectroscopy
  We demonstrate that surface relaxation, which is insignificant in trilayer graphene, starts to manifest in Bernal-stacked tetralayer graphene. Bernal-stacked few-layer graphene has been investigated by analyzing its Landau level spectra through quantum capacitance measurements. We find that in trilayer graphene, the interlayer interaction parameters were similar to that of graphite. However, in tetralayer graphene, the hopping parameters between the bulk and surface bilayers are quite different. This shows a direct evidence for the surface relaxation phenomena. In spite of the fact that the Van der Waals interaction between the carbon layers is thought to be insignificant, we suggest that the interlayer interaction is an important factor in explaining the observed results and the symmetry-breaking effects in graphene sublattice are not negligible. 
Zefei Wu, Yu Han, Wei Zhu, Mingquan He, Shuigang Xu, Xiaolong Chen,   Weiguang Ye, Tianyi Han, Huanhuan Lu, Rui Huang, Lin W...
cond-mat.mtrl-sci cond-mat.mes-hall