Some unusual electronic patterns on graphite surface |
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Authors: | Shyam K Choudhary Anjan K Gupta |
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Institution: | (1) Department of Physics, Indian Institute of Technology, Kanpur, 208 016, India |
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Abstract: | We report on the observation of some unusual electronic patterns on a graphite surface using scanning tunneling spectroscopy
(STM). We attribute these patterns to different types of strain near the surface. One such pattern seen on a particular layer
comprises of two-dimensional spatially varying super-lattice and one-dimensional fringes. This pattern is present in a finite
region of a layer on the surface confined between two carbon fibers. We attribute this spatially varying super-lattice structure
to the shear strain generated in the top layer due to the restraining fibers. We have also developed a model with the Moirè
rotation hypothesis that gives us a better insight into such largescale spatially varying patterns. We have been able to model
the above-observed pattern. We also report another pattern near a defect, which we attribute to the change in density of states
due to the physical buckling of the top graphite layer. Part of this buckled layer is found to be buried under another layer
and this region shows a reversed contrast and thus supporting our idea of buckling. We also performed tunneling spectroscopy
measurements on various regions of these patterns which show significant variations in the density of states.
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Keywords: | Graphite scanning tunneling microscopy surface structure Moirè patterns |
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