Finite-temperature Mott transitions in the multiorbital Hubbard model

We investigate the Mott transitions in the multiorbital Hubbard model at half-filling by means of the self-energy functional approach. The phase diagrams are obtained at finite temperatures for the Hubbard model with up to fourfold degenerate bands. We discuss how the first-order Mott transition points ${U}_{c1}$ and ${U}_{c2}$ as well as the critical temperature ${T}_{c}$ depend on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations play a key role to control the Mott transitions in the multiorbital Hubbard model.We investigate the Mott transitions in the multiorbital Hubbard model at half-filling by means of the self-energy functional approach. The phase diagrams are obtained at finite temperatures for the Hubbard model with up to fourfold degenerate bands. We discuss how the first-order Mott transition points ${U}_{c1}$ and ${U}_{c2}$ as well as the critical temperature ${T}_{c}$ depend on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations play a key role to control the Mott transitions in the multiorbital Hubbard model.

arXiv:cond-mat/0506150Physical Review BAug 8, 200552 citations

Single Mott transition in the multiorbital Hubbard model

A. Liebsch

The Mott transition in a multiorbital Hubbard model involving subbands of different widths is studied within the dynamical mean-field theory. Using the iterated perturbation theory for the quantum impurity problem it is shown that at low temperatures interorbital Coulomb interactions give rise to a single first-order transition rather than a sequence of orbital selective transitions. Impurity calculations based on the Quantum Monte Carlo method confirm this qualitative behavior. Nevertheless, at finite temperatures, the degree of metallic or insulating behavior of the subbands differs greatly. Thus, on the metallic side of the transition, the narrow band can exhibit quasi-insulating features, whereas on the insulating side the wide band exhibits pronounced bad-metal behavior. This complexity might partly explain contradictory results between several previous works.The Mott transition in a multiorbital Hubbard model involving subbands of different widths is studied within the dynamical mean-field theory. Using the iterated perturbation theory for the quantum impurity problem it is shown that at low temperatures interorbital Coulomb interactions give rise to a single first-order transition rather than a sequence of orbital selective transitions. Impurity calculations based on the Quantum Monte Carlo method confirm this qualitative behavior. Nevertheless, at finite temperatures, the degree of metallic or insulating behavior of the subbands differs greatly. Thus, on the metallic side of the transition, the narrow band can exhibit quasi-insulating features, whereas on the insulating side the wide band exhibits pronounced bad-metal behavior. This complexity might partly explain contradictory results between several previous works.

arXiv:cond-mat/0405410Physical Review BOct 12, 200482 citations

MOTT TRANSITION IN THE HUBBARD MODEL

B. Sriram Shastry

WORLD SCIENTIFIC eBooksApr 1, 19930 citations

Mott transition in the quasi-one-dimensional Hubbard model

Satoshi Fujimoto

Oct 6, 19990 citations

Slope-reversed Mott transition in multiorbital systems

Aaram J. Kim, M. Y. Choi, Gun Sang Jeon

We examine finite-temperature phase transitions in the two-orbital Hubbard model with different bandwidths by means of the dynamical mean-field theory combined with the continuous-time quantum Monte Carlo method. It is found that there emerges a peculiar slope-reversed first-order Mott transition between the orbital-selective Mott phase and the Mott insulator phase in the presence of Ising-type Hund's coupling. The origin of the slope-reversed phase transition is clarified by the analysis of the temperature dependence of the energy density. It turns out that the increase of Hund's coupling lowers the critical temperature of the slope-reversed Mott transition. Beyond a certain critical value of Hund's coupling the first-order transition turns into a finite-temperature crossover. We also reveal that the orbital-selective Mott phase exhibits frozen local moments in the wide orbital, which is demonstrated by the spin-spin correlation functions.We examine finite-temperature phase transitions in the two-orbital Hubbard model with different bandwidths by means of the dynamical mean-field theory combined with the continuous-time quantum Monte Carlo method. It is found that there emerges a peculiar slope-reversed first-order Mott transition between the orbital-selective Mott phase and the Mott insulator phase in the presence of Ising-type Hund's coupling. The origin of the slope-reversed phase transition is clarified by the analysis of the temperature dependence of the energy density. It turns out that the increase of Hund's coupling lowers the critical temperature of the slope-reversed Mott transition. Beyond a certain critical value of Hund's coupling the first-order transition turns into a finite-temperature crossover. We also reveal that the orbital-selective Mott phase exhibits frozen local moments in the wide orbital, which is demonstrated by the spin-spin correlation functions.

arXiv:1509.01415Physical Review BSep 14, 20151 citation

{U}_{c1}

and

{U}_{c2}

as well as the critical temperature

{T}_{c}

depend on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations play a key role to control the Mott transitions in the multiorbital Hubbard model.