Influence of electric fields on absorption spectra of AAB-stacked trilayer graphene
Chih-Wei Chiu1*, Rong-Bin Chen2, Feng-Lin Shyu3
1Department of Physics, National Kaohsiung Normal University, Kaohsiung, Taiwan
2Center of General Studies, National Kaohsiung Marine University, Kaohsiung, Taiwan
3Department of Physics, R. O. C. Military Academy, Kaohsiung, Taiwan
* presenting author:Chih-Wei Chiu,
The tight-binding model and gradient approximation are, respectively, used to calculate the band structures and the absorption spectra of AAB-stacked trilayer graphenes. Three pairs of energy bands exhibit very different energy dispersions at the low energy, and form saddle points at the middle energy. At zero electric field, $3\times 3$ excitation channels exist in both the low and middle frequencies, and cause the very rich joint density of states (JDOS). However, the structures in the JDOS are not reflected in the absorption spectra completely. For the absorption spectra, due to the different strength of the velocity metric elements among the electron states, the transitions between the same pair only make the slight contributions in the low frequency, except for the transitions between the pair of the lowest bands. Furthermore, three transitions with the similar energies at the saddle points peaks lead to a strong peak in the middle frequency. In the presence of the electric filed along the stacked direction, the energy dispersions and the energy spacings exhibit obvious variations with the change of the magnitude of the electric field, and thus the absorption spectra.

Keywords: absorption spectra, electric fields, graphene