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arXiv · 1401.0804

The ultra-low-frequency shear modes of 2-4 layer graphenes observed in their scroll structures at edges

Ping-Heng Tan·Jiang-Bin Wu·Wen-Peng Han·Wei-Jie Zhao·Xin Zhang·Hui Wang·Yu-Fang Wang
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Abstract

The in-plane shear modes between neighbor-layers of 2-4 layer graphenes (LGs) and the corresponding graphene scrolls rolled up by 2-4LGs were investigated by Raman scattering. In contrast to that just one shear mode was observed in 3-4LGs, all the shear modes of 3-4LGs were observed in 3-4 layer scrolls (LSs), whose frequencies agree well with the theoretical predication by both a force-constant model and a linear chain model. In comparison to the broad width (about 12cm$^{-1}$) for the G band in graphite, all the shear modes exhibit an intrinsic line width of about 1.0 cm$^{-1}$. The local electronic structures dependent on the local staking configurations enhance the intensity of the shear modes in corresponding 2-4LSs zones, which makes it possible to observe all the shear modes. It provides a direct evidence that how the band structures of FLGs can be sensitive to local staking configurations. This result can be extended to n layer graphene (n > 4) for the understanding of the basic phonon properties of multi-layer graphenes. This observation of all-scale shear modes can be foreseen in other 2D materials with similar scroll structures.

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Ping-Heng Tan, Jiang-Bin Wu, Wen-Peng Han, Wei-Jie Zhao, Xin Zhang, Hui Wang, Yu-Fang Wang. 2014-01-04. The ultra-low-frequency shear modes of 2-4 layer graphenes observed in their scroll structures at edges. https://doi.org/10.1103/physrevb.89.235404

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