engleski

Low-temperature specific heat of single-wall carbon nanotubes

Previous low-temperature heat capacity measurements down to 2 K have been analyzed as resulting from one-dimensional quantum confinement of single-wall carbon nanotube (SWNT) vibrational modes [J. Hone et al., Science 289, 1730 (2000)]. We extended the measurements on SWNT ropes from the same preparation technique down to 0.1 K. The specific heat shows three contributions: a well-defined T/sup -2/ term from nuclear hyperfine interactions in ferromagnetic impurities and a monotonously varying vibrational contribution very sensitive to adsorbed gases, in particular /sup 4/He. In the best outgassing conditions, the specific heat yields the T/sup 3/ term originating from intertube coupling, in agreement with J. Hone et al. [Science 289, 1730 (2000)]. The third contribution follows sublinear, power-law T dependence. We discuss our results in relation to inelastic neutron scattering experiments.

nanotubes ; thermal properties ; adsorption

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