Band and mott insulators and superconductivity in honeycomb-lattice ionic-hubbard model

Tsutomu Watanabe, Sumio Ishihara

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Motivated by superconductivity (SC) in layered nitrides, we study an ionic-Hubbard model of a honeycomb lattice, which consists of two sublattices with an energy-level offset, by an optimization variational Monte Carlo method. The parameters for the Coulomb interaction and energy-level offset to realize a band insulator in the nondoped state are evaluated, and the SC state is investigated in a carrier-doped band insulator. It is found that, in a weakly doped band insulator, spin fluctuation remains and the spin-singlet d-wave SC state is realized. Present results support an unconventional spin-singlet SC state suggested by the experimental observations in layered nitrides.

Original languageEnglish
Article number034704
Journaljournal of the physical society of japan
Issue number3
Publication statusPublished - 2013 Mar


  • Band insulator
  • Ionic-Hubbard model
  • Mott insulator
  • Nitride
  • Superconductivity
  • Variational Monte Carlo method

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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