Incidence of the Tomonaga-Luttinger liquid state on the NMR spin lattice relaxation in Carbon Nanotubes

TL;DR

This study uses NMR measurements to demonstrate that single wall carbon nanotubes exhibit Tomonaga-Luttinger liquid behavior over a wide temperature range, indicating their status as a prime example of a one-dimensional quantum metal.

Contribution

It provides experimental evidence of TLL behavior in SWCNTs through NMR, with detailed analysis of the power-law relaxation rate and its deviations at low temperatures.

Findings

Power-law temperature dependence of 1/T1 consistent with TLL.

Observed exponent smaller than two-band TLL prediction.

Gapless spin excitations at zero magnetic field.

Abstract

We report 13C nuclear magnetic resonance measurements on single wall carbon nanotube (SWCNT) bundles. The temperature dependence of the nuclear spin-lattice relaxation rate, 1/T1, exhibits a power-law variation, as expected for a Tomonage-Luttinger liquid (TLL). The observed exponent is smaller than that expected for the two band TLL model. A departure from the power law is observed only at low T, where thermal and electronic Zeeman energy merge. Extrapolation to zero magnetic field indicates gapless spin excitations. The wide T range on which power-law behavior is observed suggests that SWCNT is so far the best realization of a one-dimensional quantum metal.