Spin-dependent magnetoresistance \nin multiwall carbon nanotubes

Abstract

\n \nThe spin-dependent transport in multiwall carbon nanotubes,\nobtained by chemical vapour deposition in porous alumina\nmembranes, has been investigated. The zero-bias anomaly is shown\nto follow the typical power law $GT^{-{\\alpha}}(eV/kT)$. In the\nnanotubes contacted with $\\chem{Ni}$ pads, the magnetoresistance due\nto the spin-polarised current (SD-MR) is destroyed. In the case of\nthose contacted with $\\chem{Co}$ pads, however, the SD-MR is\nobserved. These measurements show that both the observation of a\ntypical scaling law of the conductance (for nanotubes up to\n1.5$\\un{\\mu m}$) and a short spin diffusion length (less than\n0.15$\\un{\\mu m}$ with nickel contacts and 0.7$\\un{\\mu m}$ with cobalt\ncontacts) coexist through the nanotube. This observation may be\ninterpreted in terms of a reminiscence of the Luttinger-liquid\nbehaviour with \nspin-charge separation.\n\n