Correlated Insulated Phase Suggests Bond Order between Band and Mott Insulators in Two Dimensions

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.98.016402· OSTI ID:930843

Kancharla, Srivenkateswara S ^[1]; Dagotto, Elbio R ^[1]

---

1. ORNL

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

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: ORNL LDRD Director's R&D; SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 930843
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Vol. 98; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COULOMB FIELD
ELECTRICAL INSULATORS
ENERGY GAP
GROUND STATES
HUBBARD MODEL
MEAN-FIELD THEORY
Mott Insulators
PHASE DIAGRAMS
PHASE TRANSFORMATIONS