We report on the spin dynamics of C13 isotope enriched inner walls in double-wall carbon nanotubes using C13 nuclear magnetic resonance. Contrary to expectations, we find that our data set implies that the spin-lattice relaxation time (T1) has the same temperature (T) and magnetic field (H) dependence for most of the inner-wall nanotubes detected by NMR. In the high-temperature regime (T 150K), we find that the T and H dependence of 1/T1T is consistent with a 1D metallic chain. For T 150K we find a significant increase in 1/T1T with decreasing T, followed by a sharp drop below 20K. The data clearly indicate the formation of a gap in the spin excitation spectrum, where the gap value 2Δ 40K (3.7meV) is H independent.
ASJC Scopus subject areas
- Physics and Astronomy(all)