Europhys. Lett.
Volume 67, Number 1, July 2004
Page(s) 103 - 109
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 June 2004
Europhys. Lett., 67 (1) , pp. 103-109 (2004)
DOI: 10.1209/epl/i2003-10273-1

Spin-dependent magnetoresistance in multiwall carbon nanotubes

X. Hoffer1, Ch. Klinke1, J.-M. Bonard1, L. Gravier1 and J.-E. Wegrowe2

1  IPN, Faculté des Sciences de Base, EPFL - 1015 Lausanne, Switzerland
2  LSI, Ecole Polytechnique, CNRS-UMR 7642 and CEA/DSM/DRECAM 91128 Palaiseau Cedex, France

(Received 5 September 2003; accepted in final form 27 April 2004)

The spin-dependent transport in multiwall carbon nanotubes, obtained by chemical vapour deposition in porous alumina membranes, has been investigated. The zero-bias anomaly is shown to follow the typical power law $GT^{-{\alpha}}(eV/kT)$. In the nanotubes contacted with $\chem{Ni}$ pads, the magnetoresistance due to the spin-polarised current (SD-MR) is destroyed. In the case of those contacted with $\chem{Co}$ pads, however, the SD-MR is observed. These measurements show that both the observation of a typical scaling law of the conductance (for nanotubes up to 1.5 $\un{\mu m}$) and a short spin diffusion length (less than 0.15 $\un{\mu m}$ with nickel contacts and 0.7 $\un{\mu m}$ with cobalt contacts) coexist through the nanotube. This observation may be interpreted in terms of a reminiscence of the Luttinger-liquid behaviour with spin-charge separation.

73.63.Fg - Electronic transport in nanoscale materials and structures: Nanotubes.
72.15.Nj - Collective modes (e.g., in one-dimensional conductors).
72.25.Hg - Electrical injection of spin polarized carriers.

© EDP Sciences 2004