We have observed an anomalous superperiod on a highly oriented pyrolytic graphite (HOPG) surface by scanning tunneling microscopy (STM) with period about 1.8 nm and amplitude about four times the ordinary atomic amplitude. The orientation between this structure and the atomic lattice is about 85.5 6_. After comparing several possible explanations, we propose that the rotation between the surface layer and substrate will give rise to a formation of CDW phase. Thus all the experimental results are well explained.
Applied Physics A: Materials Science & Processing
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