High temperature Luttinger liquid conductivity in carbon nanotube bundles

Abstract

The conductance and the current-voltage characteristics of metallic single wall carbon nanotube bundles have been measured between 4.2 and 330 K using 10–30 ns electric pulses to avoid overheating. The current-voltage characteristics at different temperatures collapse to a single curve when plotted in the specific coordinates following from the Tomonaga–Luttinger (T–L) liquid concept. Direct evidence is obtained for the existence of a T–L liquid phase up to 190 K and the system shows a transition between the T–L liquid state and a Mott insulating phase below 25 K.

1/f noise and mechanisms of the conductivity in carbon nanotube bundles

“…Based on the results of Ref. [8], the following conclusion can be drawn. The temperature of the sharp bend in the temperature dependence of the noise corresponds to the transition temperature from…”

“…Such contacts were ohmic over the entire temperature range of 4.2-300 K and remained stable during repeated processes of cooling and heating of the samples under study [8,10].…”

“…1). In this system, the mechanism of charge transfer at low temperatures is assumed as a hopping conductivity [8,16,17]. The quadratic dependence (1) describes the current fluctuations that occur due to changes of the linear resistance.…”

“…6), the ratio of noise levels at 300 K and 100 K is about 3. It is important that in the temperature range corresponding to the conductivity of Lüttinger liquid [8] the temperature dependence of the noise is weak. Above the temperatures corresponding to Lüttinger liquid conductivity, a sharp increase in the normalized current noise is registered.…”

“…From the low temperatures, this range is limited by the transition point from the degenerate state of the electron gas (metallic conductivity) to a non-degenerate state with the hopping conductivity. The temperature of this transition, estimated theoretically, is around T = 10-20 K. At high temperatures (at T > 200 K), according to the theoretical predictions, the quantized electronic states are destroyed, resulting in a classical behavior of electron gas and the conductivity is of a normal diffusive nature [8].…”