Correlated insulated phase suggests bond order between band and mott insulators in two dimensions.

نویسندگان

  • S S Kancharla
  • E Dagotto
چکیده

We investigate the ground state phase diagram of the half-filled repulsive Hubbard model in two dimensions in the presence of a staggered potential Delta, the so-called ionic Hubbard model, using cluster dynamical mean-field theory. We find that for large Coulomb repulsion, U >> Delta, the system is a Mott insulator (MI). For weak to intermediate values of Delta, on decreasing U, the Mott gap closes at a critical value Uc1(Delta) beyond which a correlated insulating phase with possible bond order is found. Further, this phase undergoes a first-order transition to a band insulator (BI) at Uc2(Delta) with a finite charge gap at the transition. For large Delta, there is a direct first-order transition from a MI to a BI with a single metallic point at the phase boundary.

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عنوان ژورنال:
  • Physical review letters

دوره 98 1  شماره 

صفحات  -

تاریخ انتشار 2007