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 {} in diameter and>10 {μ}m long. We find ρ_=0.03-0.10m{Ω} cm at 300 K, with positive (negative) d{ρ}/dT above (below) T = 35 K. Unoriented bulk samples exhibit similar behavior, with higher (directionally averaged) resistivities and T*'s. The high-T behavior is consistent with the predicted intrinsic metallic state for this structure.