Variable range hopping conduction in multiwalled carbon nanotubes

Abstract

An experimental study of electrical transport phenomena in magnetic-fields H up to 5 T in pressed samples of a porous system composed of multiwalled carbon nanotubes is reported. The exp[(T0/T)1/4] temperature dependence in the zero-field dc electrical resistance R(0) is found at low temperatures. Below 50 K, transverse magnetoresistance (MR), [R(H)−R(0)]/R(0), is negative. In the weak-field region (H<0.1 T), the negative MR is quadratic in H, and becomes linear in the field range 0.1–0.3 T. The linear and negative MR shows T−0.65±0.06 temperature dependence. The temperature dependence of R(0) is described in terms of Mott’s law for three-dimensional variable range hopping (3D VRH) conduction. The low-field magnetotransport features support a predicted quantum interference effect on 3D VRH conduction.