Calculation of the chirality-dependent orbital magnetic anisotropy in doped semiconducting single-walled carbon nanotubes

We calculate the orbital magnetic anisotropy (Δχ) of semiconducting single-walled carbon nanotubes at different carrier densities using a nearest-neighbor tight-binding model. Kataura plots of Δχ exhibit 2n + m family groupings and chiral index dependence at all carrier densities which are consistent with the trigonal warping effect. The diameter dependence of Δχ varies strongly with carrier density. We fit our data with a symmetry-restricted model to obtain approximate analytic expressions for Δχ as a function of nanotube chirality and carrier density. Our results illustrate the important role of doping on the magnetic properties of carbon nanotubes. Experimental studies of Δχ should take these effects into account for accurate interpretation of their results.