Numerical study of carbon nanotubes under circularly polarized irradiation
Feng Liu, Yudai Nakajima and Katsunori Wakabayashi
We numerically study the energy band structures and the corresponding wavefunctions of carbon nanotubes under circularly polarized irradiation perpendicular to the tube axis on the basis of the Floquet–Bloch theory. We focus on two typical irradiation frequencies, ħΩ γ and ħΩ ~ γ, where γ ≈ 3 eV is the hopping energy of graphene. Circularly polarized irradiation is found to open gaps for metallic zigzag nanotubes near the Fermi energy and shift the degenerate points of armchair nanotubes in the energy spectra away from the K and K’ points. Furthermore, high-frequency irradiation localizes the wavefunctions on either side of the nanotubes; in particular, the localized wavefunctions have different valley indices on each side of the nanotubes.
, , 085101 (2016)