Critical optical properties of AA- and AB-stacked graphenes
Chih-Wei Chiu1*, Ming-Fa Lin1
1Department of Physics, National Cheng-Kung University, Tainan, Taiwan
* presenting author:Chih-Wei Chiu,
The band structures and optical properties of AA- and AB-stacked multilayer graphenes are calculated by the tight-binding model and gradient approximation. For a $n_L$-layer AA-stacked graphene, there are $n_L$$^2$ excitation channels at both the low and middle frequencies. However, in the excitation spectra, there are $n_L$ peaks at both low and middle frequencies. The threshold energy of odd-layer graphene is much lower than that of even-layer graphene for $n_L< 10$. When $n_L$ grows to 30 (200), the spectra of 2D graphene are almost identical to those of 3D graphite at middle (low) frequencies. As for the AB-stacked graphene, $n_L$ ($n_L$-1) peaks exist at the low frequency for even-layer (odd-layer) systems, and one shoulder and $n_L$ peaks at the middle frequency. The critical optical properties at middle (low) frequency occur for $n_L>30$ ($n_L>50$).

Keywords: graphene, graphite, AA stacking, AB stacking, critical optical properties