  Freely suspended metallic single-wall carbon nanotubes (SWNTs) exhibit
reduced current carrying ability compared to those lying on substrates, and
striking negative differential conductance (NDC) at low electric fields.
Theoretical analysis reveals significant self-heating effects including
electron scattering by hot non-equilibrium optical phonons. Electron transport
characteristics under strong self-heating are exploited for the first time to
probe the thermal conductivity of individual SWNTs (~ 3600 Wm-1K-1 at T=300 K)
up to ~700 K, and reveal a 1/T dependence expected for Umklapp phonon
scattering at high temperatures.

Mesoscale and Nanoscale Physics