Band and Mott Insulators and Superconductivity in Honeycomb-Lattice Ionic-Hubbard Model

Tsutomu Watanabe, Sumio Ishihara
2013 Journal of the Physical Society of Japan  
Motivated by superconductivity (SC) in layered nitrides, we study an ionic-Hubbard model on a honeycomb lattice, which consists of two sublattices with an energy-level offset, by using an optimization variational Monte Carlo method. Parameter values for the Coulomb interaction and the energy-level offset, to realize a band insulator in non-doped 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
more » ... uation 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.
doi:10.7566/jpsj.82.034704 fatcat:hwikgtybdnb2jhp7izlqctai3y