NMR evidence for gapped spin excitations in metallic carbon nanotubes.
Phys Rev Lett
; 95(23): 236403, 2005 Dec 02.
Article
em En
| MEDLINE
| ID: mdl-16384324
ABSTRACT
We report on the spin dynamics of 13C isotope enriched inner walls in double-wall carbon nanotubes using 13C 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 approximately > or = 150 K), we find that the T and H dependence of 1/T1T is consistent with a 1D metallic chain. For T approximately < or = 150 K we find a significant increase in 1/T1T with decreasing T, followed by a sharp drop below approximately = 20 K. The data clearly indicate the formation of a gap in the spin excitation spectrum, where the gap value 2delta approximately = 40 K (congruent to 3.7 meV) is H independent.
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Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article