Metallic resistivity in crystalline ropes of single-wall carbon nanotubes

Laser ablation of (Co,Ni)-doped graphite yields ∼ 70% single-wall nanotubes, predominantly (10,10) armchair tubes which self-organize into crystalline ``ropes''>100 Å in diameter and>10 μm long. We find ${\mathrm{\rho }}_{\mathrm{\Vert }}$=0.03-0.10mΩ cm at 300 K, with positive (negative) dρ/dT above (below) T = 35 K. Unoriented bulk samples exhibit similar behavior, with higher (directionally averaged) resistivities and ${\mathrm{T}}^{\mathrm{*}}$'s. The high-T behavior is consistent with the predicted intrinsic metallic state for this structure.