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

Abstract

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