Evidence for Superlattice Dirac Points and Space-dependent Fermi   Velocity in Corrugated Graphene Monolayer
  Recent studies show that periodic potentials can generate superlattice Dirac points at energies in graphene (is the Fermi velocity of graphene and G is the reciprocal superlattice vector). Here, we perform scanning tunneling microscopy and spectroscopy studies of a corrugated graphene monolayer on Rh foil. We show that the quasi-periodic ripples of nanometer wavelength in the corrugated graphene give rise to weak one-dimensional (1D) electronic potentials and thereby lead to the emergence of the superlattice Dirac points. The position of the superlattice Dirac point is space-dependent and shows a wide distribution of values. We demonstrated that the space-dependent superlattice Dirac points is closely related to the space-dependent Fermi velocity, which may arise from the effect of the local strain and the strong electron-electron interaction in the corrugated graphene. 
Hui Yan, Zhao-Dong Chu, Wei Yan, Mengxi Liu, Lan Meng, Mudan Yang,   Yide Fan, Jiang Wang, Rui-Fen Dou, Yanfeng Zhang, Zhong...
cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el