Dynamical symmetry enlargement in metallic zigzag carbon nanotubes

Abstract

We revisit correlation effects in doped metallic zigzag carbon nanotubes by using both the one-loop renormalization group and nonperturbative bosonization techniques. Note that, if a nanotube is placed near a conducting plate, the long-range Coulomb interactions are screened and the resulting short-range interactions can be modeled by on-site and nearest-neighbor repulsive interactions U, V, and V⊥, respectively. Using both analytic and numeric means, we determine the phase diagram of the ground states. For U∕t<0.5 (t is the hopping strength), dynamical symmetry enlargement occurs and the low-energy excitations are described by the SO(6) Gross-Neveu model. However, for realistic material parameters U∕t∼O(1), the charge sector decouples but there remains an enlarged SO(4) symmetry in the spin sector.