Thermal conductivity of single-walled carbon nanotubes

We have measured the temperature-dependent thermal conductivity $\kappa \mathrm{}\left(T\right)\mathrm{}$ of crystalline ropes of single-walled carbon nanotubes from 350 K to 8 K. $\kappa \mathrm{}\left(T\right)\mathrm{}$ decreases smoothly with decreasing temperature, and displays linear temperature dependence below 30 K. Comparison with electrical conductivity experiments indicates that the room-temperature thermal conductivity of a single nanotube may be comparable to that of diamond or in-plane graphite, while the ratio of thermal to electrical conductance for a given sample indicates that the thermal conductivity is dominated by phonons at all temperatures. Below 30 K, the linear temperature dependence and estimated magnitude of $\kappa \mathrm{}\left(T\right)\mathrm{}$ imply an energy-independent phonon mean free path of ∼0.5–1.5 μm.