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Stacking-Dependent Optical Conductivity Of Bilayer Graphene, Yingying Wang, Zhenhua Ni, Lei Liu, Yanhong Liu, Chunxiao Cong, Ting Yu, Xiao-Jun Wang, Dezhen Shen, Zexiang Shen

Department of Physics and Astronomy Faculty Publications

The optical conductivities of graphene layers are strongly dependent on their stacking orders. Our first-principle calculations show that, while the optical conductivities of single-layer graphene (SLG) and bilayer graphene (BLG) with Bernal stacking are almost frequency-independent in the visible region, the optical conductivity of twisted bilayer graphene (TBG) is frequency-dependent, giving rise to additional absorption features due to the band folding effect. Experimentally, we obtain from contrast spectra the optical conductivity profiles of BLG with different stacking geometries. Some TBG samples show additional features in their conductivity spectra, in full agreement with our calculation results, while a few samples give …