We consider a narrow one-dimensional tight-binding chain with intra-atomic Coulomb repulsions described in the Hubbard model. The electrons at each site are furthermore assumed to be coupled to a high-frequency local oscillator. In the limit where the oscillator frequency is large compared to the bandwidth, and in the extreme-band-narrowing regime, for various electron densities, we find that: the half-filled-band ground state is an antiferromagnetic insulator; the one-third-filled-band ground state is a diamagnetic insulator; and the one-quarter-filled-band ground state is a weakly coupled system of bound singlet pairs somewhat reminiscent of superconductivity.We consider a narrow one-dimensional tight-binding chain with intra-atomic Coulomb repulsions described in the Hubbard model. The electrons at each site are furthermore assumed to be coupled to a high-frequency local oscillator. In the limit where the oscillator frequency is large compared to the bandwidth, and in the extreme-band-narrowing regime, for various electron densities, we find that: the half-filled-band ground state is an antiferromagnetic insulator; the one-third-filled-band ground state is a diamagnetic insulator; and the one-quarter-filled-band ground state is a weakly coupled system of bound singlet pairs somewhat reminiscent of superconductivity.

Physical review. B, Solid stateSep 1, 197460 citations

The Hubbard model and the metal-insulator phase transition

J. O. Lawson

Physics Letters AJul 1, 19745 citations

Orbital-selective Mott-Hubbard transition in the two-band Hubbard model

Ryotaro Arita, Karsten Held

Recent advances in the field of quantum Monte Carlo simulations for impurity problems allow---within dynamical mean field theory---for a more thorough investigation of the two-band Hubbard model with a narrow-wide band and SU(2)-symmetric Hund's exchange. The nature of this transition has been controversial, and we establish that an orbital-selective Mott-Hubbard transition exists. The wide band still shows metallic behavior after the narrow band became insulating---not a pseudogap as for an Ising Hund's exchange. The coexistence of two solutions with a metallic wide band and an insulating or metallic narrow band indicates, in general, first-order transitions.Recent advances in the field of quantum Monte Carlo simulations for impurity problems allow---within dynamical mean field theory---for a more thorough investigation of the two-band Hubbard model with a narrow-wide band and SU(2)-symmetric Hund's exchange. The nature of this transition has been controversial, and we establish that an orbital-selective Mott-Hubbard transition exists. The wide band still shows metallic behavior after the narrow band became insulating---not a pseudogap as for an Ising Hund's exchange. The coexistence of two solutions with a metallic wide band and an insulating or metallic narrow band indicates, in general, first-order transitions.

arXiv:cond-mat/0504040Physical Review BNov 29, 200579 citations

Interaction-driven Band-insulator--to--Metal transition in bilayer ionic Hubbard model

Mi Jiang, T. C. Schulthess

The interaction-driven insulator-to-metal transition has been reported in the ionic Hubbard model (IHM) for moderate interaction $U$ , while its metallic phase only occupies a narrow region in the phase diagram. To explore the enlargement of the metallic regime, we extend the ionic Hubbard model to two coupled layers and study the interplay of interlayer hybridization $V$ and two types of intralayer staggered potentials $Δ$ : one with the same (in-phase) and the other with a $π$ -phase shift (anti-phase) potential between layers. Our determinant Quantum Monte Carlo (DQMC) simulations at lowest accessible temperatures demonstrate that the interaction-driven metallic phase between Mott and band insulators expands in the $Δ-V$ phase diagram of bilayer IHM only for in-phase ionic potentials; while anti-phase potential always induces an insulator with charge density order. This implies possible further extension of the ionic Hubbard model from the bilayer case here to realistic three-dimensional model.The interaction-driven insulator-to-metal transition has been reported in the ionic Hubbard model (IHM) for moderate interaction $U$, while its metallic phase only occupies a narrow region in the phase diagram. To explore the enlargement of the metallic regime, we extend the ionic Hubbard model to two coupled layers and study the interplay of interlayer hybridization $V$ and two types of intralayer staggered potentials $Δ$: one with the same (in-phase) and the other with a $π$-phase shift (anti-phase) potential between layers. Our determinant Quantum Monte Carlo (DQMC) simulations at lowest accessible temperatures demonstrate that the interaction-driven metallic phase between Mott and band insulators expands in the $Δ-V$ phase diagram of bilayer IHM only for in-phase ionic potentials; while anti-phase potential always induces an insulator with charge density order. This implies possible further extension of the ionic Hubbard model from the bilayer case here to realistic three-dimensional model.

arXiv:1604.03271Apr 12, 20161 citation

Metal-insulator transition in the Hubbard model

R. Bulla, Thomas Pruschke, Alex C. Hewson

Physica B Condensed MatterJan 1, 19999 citations

The interaction-driven insulator-to-metal transition has been reported in the ionic Hubbard model (IHM) for moderate interaction

U

, while its metallic phase only occupies a narrow region in the phase diagram. To explore the enlargement of the metallic regime, we extend the ionic Hubbard model to two coupled layers and study the interplay of interlayer hybridization

V

and two types of intralayer staggered potentials

Δ

: one with the same (in-phase) and the other with a

π

-phase shift (anti-phase) potential between layers. Our determinant Quantum Monte Carlo (DQMC) simulations at lowest accessible temperatures demonstrate that the interaction-driven metallic phase between Mott and band insulators expands in the

Δ-V

phase diagram of bilayer IHM only for in-phase ionic potentials; while anti-phase potential always induces an insulator with charge density order. This implies possible further extension of the ionic Hubbard model from the bilayer case here to realistic three-dimensional model.