Abstract
The electronic structure of massless Dirac fermion in the graphene hexagonal bipartite is seriously modified by the presence of edges depending on the edge chirality. In the zigzag edge, strongly spin polarized nonbonding edge state is created as a consequence of broken symmetry of pseudo-spin. In the scattering at armchair edges, the K-K’ intervalley transition gives rise to electron wave interference. The presence of edge state in zigzag edges is observed in ultra-high vacuum STM/STS observations. The electron wave interference phenomenon in the armchair edge is observed in the Raman G-band and the honeycomb superlattice pattern with its fine structure in STM images.
Highlights
The electronic structure of massless Dirac fermion in the graphene hexagonal bipartite is seriously modified by the presence of edges depending on the edge chirality
The electron wave interference phenomenon in the armchair edge is observed in the Raman G-band and the honeycomb superlattice pattern with its fine structure in STM images
The electronic structure of massless Dirac fermion moving on the hexagonal bipartite lattice is modified seriously by the presence of edges depending on the edge chirality
Summary
It is important to show the evidence on the presence of edge state using scanning tunneling microscopy/spectroscopy (STM/STS) technique in atomic resolution [10,11,12]. The STS spectrum demonstrates that the electronic structure in the vicinity of the Fermi level (EF) is the same to that of infinite graphene sheet with a feature of massless Dirac fermion described in terms of linear valence - and conduction *-bands which touch to each other at EF [4]. This reflects the lattice image which shows a 3 3 superlattice structure with no additional contribution. The bright spots observed in the zigzag edge region (Fig.5(c)) are ascribed to the edge state
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