Magnetoconductance in single-wall carbon nanotubes: Electron-electron interaction and weak localization contributions

The positive and negative magnetoconductance (MC) data [J. Vavro et al., Phys. Rev. B 71, 155410 (2005)] in various single-wall carbon nanotube samples are analyzed by taking into account the electron-electron interaction (EEI) contribution, in addition to the weak localization (WL) regime. The low field MC data shows an $H^2$ dependence, in accordance with the EEI and WL models. The contribution from EEI to the total MC is further confirmed from the universal scaling of MC relation [$\{\Delta \sigma ∕T^{1∕2}\}$ vs $(H∕T)$ plots], showing that EEI plays a significant role at higher fields and lower temperatures. Intrinsic parameters such as inelastic scattering length $\left(l_{\mathit{in}}\right)$ extracted for barely metallic sample ($120\mathrm{S}∕\mathrm{cm}$ at $300\mathrm{K}$) follow the $T^{-3∕4}$ dependence due to the inelastic electron-electron scattering in the dirty limit. The $l_{\mathit{in}}$ for highly conducting sample ($3570\mathrm{S}∕\mathrm{cm}$ at $300\mathrm{K}$) follows a $T^{-0.4}$ dependence. The various order parameters helps us to characterize the system in a disorder-tuned metal-insulator transition scenario.

Figure 1

Conductivity vs temperature for SWNT samples.

Figure 2

Magnetoconductance vs field: (a) HPR neat, (b) HPR T600, and (c) PLV undoped.

Figure 3

The universal scaling of MC $(\Delta \sigma ∕T^{1∕2})$ vs $H∕T$: (a) HPR T600 and (b) PLV undoped. The solid lines are the fits to Eq. (8).

Figure 4

Inelastic scattering length vs temperature: (a) PLV undoped and (b) HPR neat.

Figure 5

Magnetoconductance vs field. The solid lines are fits, to Eq. (5) in the low field, and to Eq. (6) in the high field regime.