Fig. 3: Electronic structures of folded and exposed graphene.
From: Pseudo-Landau levels splitting triggers quantum friction at folded graphene edge
a, b Scanning tunneling microscope (STM) topographic images of the 2 L exposed edge and 1 L + 1 L fold and the corresponding spatial resolved dI/dV spectra obtained at the marked positions, respectively. c Linear pseudo-Landau level (PLL) energies versus \({{\mathrm{sgn}}}\left(n\right)\sqrt{\left|n\right|(\left|n\right|+1)}\) extracted from (b). The black dashed line is linear fit against the experimental data. d Experimental topographic line scan and experimental calculated Bs profile along the direction perpendicular to the 1 L + 1 L folded edge. Inset: radius of the curvature at different positions. Error bars represent the standard deviations obtained by measuring four different locations along the axial direction of the folded edge. e Extracted Bs at different positions along the folded edge axis for 1 L + 1 L, 3 L + 3 L and 5 L + 5 L. Inset: topographic images where the black arrows represent the measured positions of the corresponding STS spectra. f, g Representative dI/dV spectra and corresponding Bs values of 1 L + 1 L, 3 L + 3 L, 5 L + 5 L, 7 L + 7 L folded graphene edges and bulk graphite, respectively. Error bars represent the standard deviations obtained by measuring ten different locations along the axial direction of the folded edges at the same layer number. h A schematic illustration of energy band structures in differ-layer-fold graphene. Folded graphene edges exhibit discrete pseudo-Landau levels below 14 layers and demonstrate a continuous energy band structure beyond 14 layers.
