Metallic resistivity in crystalline ropes of single-wall carbon nanotubes

Laser ablation of (Co,Ni)-doped graphite yields similar to 70% single-wall nanotubes, predominantly (10,10) armchair tubes which self-organize into crystalline ''ropes''>100 Angstrom in diameter and>10 mu m long. We find rho(parallel to)=0.03-0.10 m Omega cm at 300 K, with positive (negative) d rho/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.