Low-temperature specific heat of double wall carbon nanotubes

We report the analysis on the low-temperature specific heat of the double-walled carbon nanotubes (DWNTs) in the temperature range between 0.3 and 30 K, in comparison with that of the single-walled carbon nanotubes (SWNTs). The low-temperature specific heat of the SWNTs can be analyzed in terms of the acoustic phonon modes and the neighboring-tube interactions (αT3), which are in good agreement with earlier reports. The low-temperature specific heat of the DWNTs is smaller than that of the SWNTs. Taking account of the theoretical framework of the DWNT proposed by Damnjanovic et al. and the neighboring-tube interactions (CT3), the measured low-temperature specific heat of the DWNTs is well consistent with the theoretical predication. Our experimental results indicate that the neighboring-tube and intralayer interactions are not negligible in the low-temperature specific heat of the DWNTs.