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 long. We find _=0. 03-0. 10m cm at 300 K, with positive (negative) d/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.