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The shear mode of multilayer graphene

2012; Nature Portfolio; Volume: 11; Issue: 4 Linguagem: Inglês

10.1038/nmat3245

1476-4660

Ping‐Heng Tan, W. P. Han, Weijie Zhao, Zhenhua Wu, Kai Chang, Haozheng Wang, Ye Wang, Nicola Bonini, Nicola Marzari, Nicola M. Pugno, G. Savini, Antonio Lombardo, Andrea C. Ferrari,

Topological Materials and Phenomena

Raman spectroscopy has already proved to be a powerful tool for studying the properties of single graphene layers. It is now shown that this technique can also provide information on the interaction between graphene sheets in multilayered graphene structures. In particular, a Raman peak corresponding to the interlayer shear mode, and probably linked to the interlayer coupling, is unveiled. The quest for materials capable of realizing the next generation of electronic and photonic devices continues to fuel research on the electronic, optical and vibrational properties of graphene. Few-layer graphene (FLG) flakes with less than ten layers each show a distinctive band structure. Thus, there is an increasing interest in the physics and applications of FLGs. Raman spectroscopy is one of the most useful and versatile tools to probe graphene samples. Here, we uncover the interlayer shear mode of FLGs, ranging from bilayer graphene (BLG) to bulk graphite, and suggest that the corresponding Raman peak measures the interlayer coupling. This peak scales from ~43 cm−1 in bulk graphite to ~31 cm−1 in BLG. Its low energy makes it sensitive to near-Dirac point quasiparticles. Similar shear modes are expected in all layered materials, providing a direct probe of interlayer interactions.