The structure and electronic properties of potassium-doped single-wall carbon nanotubes have been studied by conduction electron spin resonance, conductivity $\left(\sigma \right),$ and x-ray diffraction (XRD), using in situ electrochemical methods. The spin susceptibility ${\chi }_P$ of the K-saturated phase is independent of temperature; a lower bound is $5\times {10}^{-8}\mathrm{e}\mathrm{m}\mathrm{u}/\mathrm{g}.$ At 300 K both $\sigma$ and ${\chi }_P$ increase monotonically and reversibly with K/C. The spin relaxation rate and g factor do not change with doping, and XRD reveals an irreversible loss of crystallinity upon doping. We propose an inhomogeneous doping model to explain these results.

• Received 3 May 2000

DOI:https://doi.org/10.1103/PhysRevB.62.R4845