Hui Yan, Zhao-Dong Chu, Wei Yan, Mengxi Liu, Lan Meng, Mudan Yang, Yide Fan, Jiang Wang, Rui-Fen Dou, Yanfeng Zhang, Zhongfan Liu, Jia-Cai Nie, Lin He
Recent studies show that periodic potentials can generate superlattice Dirac points at energies in graphene (VF is the Fermi velocity of graphene and G is the reciprocal superlattice vector). Here, we performed scanning tunneling microscopy and spectroscopy studies of 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 appearance of the superlattice Dirac points reflects the highly anisotropic behaviors of massless Dirac fermions, resulting from the chiral nature of the massless Dirac excitations, in the 1D periodic potential. Furthermore, our experimental results demonstrate that the corrugated graphene has a space-dependent Fermi velocity, which is attributed to the effect of the local strain and the strong electron-electron interaction.
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http://arxiv.org/abs/1209.1689
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