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Carbon nanotubes as excitonic insulators.

ABSTRACT: Fifty years ago Walter Kohn speculated that a zero-gap semiconductor might be unstable against the spontaneous generation of excitons-electron-hole pairs bound together by Coulomb attraction. The reconstructed ground state would then open a gap breaking the symmetry of the underlying lattice, a genuine consequence of electronic correlations. Here we show that this excitonic insulator is realized in zero-gap carbon nanotubes by performing first-principles calculations through many-body perturbation theory as well as quantum Monte Carlo. The excitonic order modulates the charge between the two carbon sublattices opening an experimentally observable gap, which scales as the inverse of the tube radius and weakly depends on the axial magnetic field. Our findings call into question the Luttinger liquid paradigm for nanotubes and provide tests to experimentally discriminate between excitonic and Mott insulators.

SUBMITTER: Varsano D

PROVIDER: S-EPMC5684388 | biostudies-other | 2017 Nov

REPOSITORIES: biostudies-other

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Carbon nanotubes as excitonic insulators.

Varsano Daniele D Sorella Sandro S Sangalli Davide D Barborini Matteo M Corni Stefano S Molinari Elisa E Rontani Massimo M

Nature communications 20171113 1

Fifty years ago Walter Kohn speculated that a zero-gap semiconductor might be unstable against the spontaneous generation of excitons-electron-hole pairs bound together by Coulomb attraction. The reconstructed ground state would then open a gap breaking the symmetry of the underlying lattice, a genuine consequence of electronic correlations. Here we show that this excitonic insulator is realized in zero-gap carbon nanotubes by performing first-principles calculations through many-body perturbati ...[more]

PMID: 29133914

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