Electrical resistance of a carbon nanotube bundle
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L. Stockman Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgique
J. P. Heremans Physics Department, General Motors Research, Warren, Michigan 48090
V. Bayot Unite de Physico-Chimie et de Physique des Materiaux, Universite Catholique de Louvain, 1 Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgique
C. H. Oik Physics Department, General Motors Research, Warren, Michigan 48090
C. Van Haesendonck and Y. Bruynseraede Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgique
J-P. Issi Unite de Physico-Chimie et de Physique des Materiaux, Universite Catholique de Louvain, 1 Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgique (Received 24 November 1993; accepted 8 December 1993)
The first direct electrical resistance measurements performed on a single carbon nanotube bundle from room temperature down to 0.3 K and in magnetic fields up to 14 T are reported. From the temperature dependence of the resistance above 2 K, it is shown that some nanotubes exhibit a semimetallic behavior akin to rolled graphene sheets with a similar band structure, except that the band overlap, A ~ 3.7 meV, is about 10 times smaller than for crystalline graphite. In contrast to graphite which shows a constant low-temperature resistivity, the nanotubes exhibit a striking increase of the resistance followed by a broad maximum at very low temperatures. A magnetic field applied perpendicular to the sample axis decreases the resistance. Above 1 K, this behavior is consistent with the formation of Landau levels. At lower temperatures, the resistance shows an unexpected drop at a critical temperature which increases linearly with magnetic field. These striking features could be related to the unique quasi-one-dimensional structure of the carbon nanotubes.
I. INTRODUCTION Recently, Iijima1 discovered graphite needles, thereafter called carbon nanotubes, which have diameters of the order of nanometers. This new class of quasione-dimensional (quasi-ID) systems has stimulated a large number of theoretical studies on their electronic properties.2"8 Theory predicts that nanotubes can either be metals, semimetals, or semiconductors, depending on their diameter and degree of helicity. A magnetic field is expected to induce the formation of Landau levels.7 Experimental verification of these predictions has been considered very delicate because of the very small size of individual nanotubes9 or nanotube bundles.10 The aim of the present work is to give a preliminary answer to this question. J. Mater. Res., Vol. 9, No. 4, Apr 1994 http://journals.cambridge.org
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It has been previously shown that the scanning tunneling microscope (STM) can be successfully used for the submicrometer lithographic patterning of gold films which have been covered with a Langmuir-Blodgett layer of electron-beam resist.11 Using this powerful technique we succeeded in attaching electrical contacts to individua
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