Landau quantization and Fermi velocity renormalization in twisted graphene bilayers

Long Jing Yin, Jia Bin Qiao, Wen Xiao Wang, Wei Jie Zuo, Wei Yan, Rui Xu, Rui Fen Dou, Jia Cai Nie, Lin He

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63 引用 (Scopus)

摘要

Currently there is a lively discussion concerning Fermi velocity renormalization in twisted bilayers and several contradicted experimental results are reported. Here we study electronic structures of the twisted bilayers by scanning tunneling microscopy (STM) and spectroscopy (STS). The interlayer coupling strengths between the adjacent bilayers are measured according to energy separations of two pronounced low-energy van Hove singularities (VHSs) in the STS spectra. We demonstrate that there is a large range of values for the interlayer interaction not only in different twisted bilayers, but also in twisted bilayers with the same rotation angle. Below the VHSs, the observed Landau quantization in the twisted bilayers is identical to that of massless Dirac fermions in graphene monolayer, which allows us to measure the Fermi velocity directly. Our result indicates that the Fermi velocity of the twisted bilayers depends remarkably on both the twisted angles and the interlayer coupling strengths. This removes the discrepancy about the Fermi velocity renormalization in the twisted bilayers and provides a consistent interpretation of all current data.

源语言英语
文章编号201408
期刊Physical Review B - Condensed Matter and Materials Physics
92
20
DOI
出版状态已出版 - 10 11月 2015
已对外发布

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