Beyond the Linearity of Current-Voltage Characteristics in Multiwalled   Carbon Nanotubes
  We present local and non-local electron transport measurements on individual multi-wall nanotubes for bias voltage between 0 and about 4 V. Local current-voltage characteristics are quite linear. In contrast, non-local measurements are highly non-linear; the differential non-local conductance can even become negative in the high-bias regime. We discuss the relationship between these results and transport parameters such as the elastic length, the number of current carrying shells, and the number of conducting modes. 
B. Bourlon, C. Miko, L. Forro, D.C. Glattli, A. Bachtold