Overlapping of linear optical spectra in metallic carbon nanotubes, Controlled by applied axial magnetic field and uniaxial strain

Abstract

The excitons and absorption spectra of M11 and M22 transitions in metallic carbon nanotubes were calculated by the tight-binding model, under the combined effect of axial magnetic field and uniaxial strain. It is interesting to find that the separated absorption peaks induced by axial magnetic field will meet each other when the uniaxial strain is applied. At the same axial magnetic field, the first overlapping point is appeared for Mii−−2 and Mii+−1 exciton with small uniaxial strain, and the biggest uniaxial strain is needed for Mii−−1 and Mii+−2 exciton. When we change the magnitude of the axial magnetic field, the overlapping point displays different variation trend for four separate excitons. This overlapping phenomenon is also occurred for other metallic tubes: with bigger diameter, smaller uniaxial strain is needed. More important is that an useful tool is offered to regulate the optical properties of carbon nanotubes by applying simultaneously the axial magnetic field and uniaxial strain.