Metallic resistivity in crystalline ropes of single-wall carbon nanotubes

Abstract

Laser ablation of (Co,Ni)-doped graphite yields \ensuremath{\sim} 70% single-wall nanotubes, predominantly (10,10) armchair tubes which self-organize into crystalline ``ropes''>100 \AA{} in diameter and>10 \ensuremath{\mu}m long. We find ${\mathrm{\ensuremath{\rho}}}_{\mathrm{\ensuremath{\Vert}}}$=0.03-0.10m\ensuremath{\Omega} cm at 300 K, with positive (negative) d\ensuremath{\rho}/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.