Exciton states in metallic zigzag single-walled carbon nanotubes under uniaxial strain

Abstract The exciton energy spectrum and its binding energy under the uniaxial strain have been theoretically studied by using the tight-binding model in the metallic zigzag single-walled carbon nanotubes (SWNTs). It is found that the energy of M 11 - and M 22 - excitons and their binding energies increase with the increase of uniaxial strain, but the energy of M 11 + and M 22 + excitons and their binding energies decrease as the uniaxial strain increase. So, we can deduce that the splitting of M 11 and M 22 exciton will disappear as the uniaxial strain increases up to some degree, which is expected to be detected by the future experiment. On the other hand, it is interesting to calculate the exciton energy spectrum and binding energies of the bands that nearest to the Fermi level, with a narrow gap under the uniaxial strain. The obtained results show that they increase with increasing the uniaxial strain, based on which a supplemented tool is offered to detect the deformation degree of a metallic SWNT under uniaxial strain. In addition, we expect the results obtained here can offer some useful information for the future THz applications.