title: Shell filling in closed single-wall carbon nanotube quantum dots.
abstract: We observe twofold shell filling in the spectra of closed one-dimensional quantum dots formed in single-wall carbon nanotubes. Its signatures include a bimodal distribution of addition energies, correlations in the excitation spectra for different electron number, and alternation of the spins of the added electrons. This provides a contrast with quantum dots in higher dimensions, where such spin pairing is absent. We also see indications of an additional fourfold periodicity indicative of K-K' subband shells. Our results suggest that the absence of shell filling in most isolated nanotube dots results from disorder or nonuniformity.
authors.affiliation: Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA. cobden@phys.washington.edu
authors.forename: David H
authors.initials: DH
authors.lastname: Cobden
authors.forename: Jesper
authors.initials: J
authors.lastname: Nygård