Stability of the Tomonaga–Luttinger liquid state in gamma-irradiated carbon nanotube bundles

We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by 60Co γ-rays in various environments. In the current study the samples investigated were irradiated in hermetic cells, either evacuated (0.1 Pa) or filled with hydrogen or deuterium at atmospheric pressure. In situ measurements of the resistance change as a function of irradiation dose at room temperature are presented. It was found that, for all irradiation conditions, the normalized resistance versus irradiation dose demonstrates a logarithmic behaviour. A phenomenological model for the observed dependence is derived. The current–voltage characteristics of the irradiated samples were measured in the temperature range from 4.5 to 300 K using short (10 ns) electric pulses, and the results demonstrate a scaling behaviour. This scaling occurs in the universal coordinates that correspond to the Tomonaga–Luttinger liquid concept. Our results confirm the existence of the Tomonaga–Luttinger liquid phase up to room temperature in carbon nanotubes after γ-irradiation to a dose of 5 × 107 rad in vacuum, 1.7 × 107 rad in hydrogen and 1.24 × 108 rad in deuterium. (paper)