Authors: P.G. Gabrielli, S. Gabrielli, N. Lisi
Affilation: ENEA, Italy
Pages: 51 - 54
Keywords: resistance measurement, quantum transport, weak localization
In the theory of the 1-d electron systems, called Tomonaga-Luttinger-liquid (LL), the correlated electron state is characterized by a parameter g that measures the strength of the interaction between the electrons (g=1 for non-interacting electron gas). The most important feature of the LL, in contrast to Landau Fermi-Liquid theory (FL), is the absence of the fermion quasiparticle branch at low energy: excited states of the system must be described by the bosonic fluctuations of the charge and spin densities dispersing with different velocities, which correspond to many-body electron state with a huge number of the electron-hole pairs. This have a pronounced effect on the tunneling into a LL conductor: the IV curve of a tunnel junction between a normal FL and a LL conductor is expected to be non-ohmic and described by a power law with an exponent depending on interaction strength. In the last few years much theoretical and experimental attention has been focused on the electrical properties of single-walled carbon nanotubes (SWNTs). Evidence has emerged pointing towards the existence of LL in metallic SWNT, as expected for strongly interacting electrons in 1-d, such behavior was observed via the power law temperature and bias-voltage dependence of the current through tunneling contacts attached to the nanotubes. In particular recent advances in the growth of extremely long nanotube ( >1 mm) have allowed for experimental measurements on the scaling behavior of resistance in individual, millimeter long SWNT for the temperature range of 1.6-300 K. From the linear scaling of resistance, the temperature dependent electron mean free path has been calculated for each temperature and, beyond the linear scaling regime, it has been observed that the resistance increases exponentially with length, indicating localization behavior. In this work we present the results of the resistance measurements of different lengths SWNT indicating the weak localization behavior.