Doping- and size-dependent suppression of tunneling in carbon nanotubes -: art. no. 085404

We study the effect of doping in the suppression of tunneling observed in multi-walled nanotubes, incorporating as well the influence of the finite dimensions of the system. A scaling approach allows us to encompass the different values of the critical exponent alpha measured for the tunneling density of states in carbon nanotubes. We predict that further reduction of alpha should be observed in multi-walled nanotubes with a sizable amount of doping. In the case of nanotubes with a very large radius, we find a pronounced crossover between a high-energy regime with persistent quasiparticles and a low-energy regime with the properties of a one-dimensional conductor.