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キーワード:
carbon nanotubes; magneto-resistance
要旨:
The orientation dependence of magneto-resistance behaviour for
a single-walled carbon nanotube (SWCN) rope is reported. A
clear delineation of behaviours is observed between applying a
magnetic field perpendicular or parallel to the rope axis. For
a perpendicular field, monotonic negative magneto-resistance is
observed due to two-dimensional weak localisation within the
rope. By contrast, for a parallel field, complicated
oscillatory behaviour is observed due to the Altshuler-Aronov-
Spivak effect around closed electron trajectories on discrete
cylinders within the SWCN rope. A dominant oscillatory mode can
be identified which corresponds to closed paths around the
outer circumference of the SWCN rope. However, due to the
composite filamentary nature of the rope, the overall
oscillatory behaviour is rather complicated and can be
classified as universal conductance fluctuations. With a
backgate voltage applied to the sample, Coulomb blockade peaks
are observed in the transport current with additional peak
structure superimposed due to resonant tunnelling. We find an
interesting effect whereby these peaks are suppressed in the
presence of a magnetic field. (C) 2002 Elsevier Science B.V.
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