Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Modern Physics Letters B

OPTICAL CONDUCTIVITY AND ORBITAL SUSCEPTIBILITY OF THE TWO-ORBITAL HUBBARD MODEL: EXTENDED LINEARIZED DYNAMICAL MEAN-FIELD THEORY

Yun Song

Published Jul 30, 2009• 0 citations
Publisher

Abstract

We study the optical conductivity and orbital susceptibility of the two-orbital Hubbard model within the extended linearized dynamical mean-field theory. In the orbital-selective Mott phase (OSMP), the optical conductivity of the wide band presents a non-zero Drude peak, while the optical conductivity of the narrow band drops to zero in the lower energy region. It is shown that the OSMP is constrained by the negative crystal-field splitting, while it can survive in the region with positive crystal-field splitting. We also find that the orbital susceptibility presents a reversion at Fermi surface in the OSMP regime, which implies that orbital ordering can coexist with OSMP in two-orbital systems.

DOI
10.1142/s0217984909020485

Related papers

Orbital-selective Mott transitions in a doped two-band Hubbard model with crystal field splitting

Eberhard Jakobi, Nils Blümer, P. G. J. van Dongen

We investigate the effects of crystal field splitting in a doped two-band Hubbard model with different bandwidths within dynamical mean-field theory (DMFT), using a quantum Monte Carlo impurity solver. In addition to an orbital-selective Mott phase (OSMP) of the narrow band, which is adiabatically connected with the well-studied OSMP in the half-filled case without crystal field splitting, we find, for sufficiently strong interaction and a suitable crystal field, also an OSMP of the wide band. We establish the phase diagram (in the absence of magnetic or orbital order) at moderate doping as a function of interaction strength and crystal field splitting and show that also the wide-band OSMP is associated with non-Fermi-liquid behavior in the case of Ising-type Hund rule couplings. Our numerical results are supplemented by analytical strong-coupling studies of spin order and spectral functions at integer filling.

arXiv:1301.7252•Physical Review B•May 28, 2013•25 citations

Dynamical mean-field theory of two-orbital Hubbard model

Yu Hua Ni, Jian Colin Sun, Ya‐Min Quan +2 more

The effect of interorbital hopping on orbital selective Mottness in a two-band correlation system is investigated by using the dynamical mean-field theory with the Lanczos method as impurity solver. The phase diagrams of the two-orbital Hubbard model with non-local interorbital hopping (t12) , where the orbital selective Mott phases (OSMP) region is expanded by the increasing of the interorbital hopping. We compare the results obtained by self-consistent relations of Bethe lattice and squate lattice based on DMFT procedure, and the general OSMP physics of Bethe lattice is consistent with that of the square lattice while the critical points of two kinds of lattices are different. We extend the method to the study of half-filled Ba2CuO4–δ materials. By comparing with the band structure obtained from the density functional theory (DFT), it is found that the isotropic inter-orbital hopping has a great influence on the bandstructure. The DFT bandstructure in DMFT is considered, and the phase diagram of the material is obtained. The half-filled Ba2CuO4–δ should be orbital-selective Mott compound according to our results.

Acta Physica Sinica•Jan 1, 2022•1 citation

Evolution between two orbital-selective Mott phases driven by interorbital hopping

Yu Hua Ni, Jian Sun, Ya‐Min Quan +1 more

The effect of interorbital hopping on the orbital selective Mottness in a two-band correlation system is investigated by using the dynamical mean-field theory with the Lanczos method as impurity solver. We construct the phase diagram of the two-orbital Hubbard model with interorbital hopping ($t_{12})$, where the orbital selective Mott phases (OSMP) show different evolution trends. We find that the negative interorbital hopping ($t_{12}<0$) can enhance the OSMP regime upon tuning the effective bandwidth ratio. On the contrary, for the cases with positive interorbital hopping ($t_{12}>0$), the OSMP region becomes narrow with the increase of orbital hybridization until it disappears. It is also shown that a new OSMP emerges for a large enough positive interorbital hopping, owing to the role exchange of wide and narrow effective orbitals caused by the large $t_{12}$. Our results are also applicable to the hole-overdoped Ba$_2$CuO$_{4-δ}$ superconductor, which is an orbital-selective Mott compound at half-filling.

arXiv:2112.04664•Dec 9, 2021•0 citations

Orbital-selective Mott transition in multiband systems: Slave-spin representation and dynamical mean-field theory

Luca de’ Medici, Antoine Georges, Silke Biermann

We examine whether the Mott transition of a half-filled, two-orbital Hubbard model with unequal bandwidths occurs simultaneously for both bands or whether it is a two-stage process in which the orbital with narrower bandwith localizes first (giving rise to an intermediate ``orbital-selective'' Mott phase). This question is addressed using both dynamical mean-field theory and a representation of fermion operators in terms of slave quantum spins, followed by a mean-field approximation (similar in spirit to a Gutzwiller approximation). In the latter approach, the Mott transition is found to be orbital selective for all values of the Coulomb exchange (Hund) coupling $J$ when the bandwidth ratio is small and only beyond a critical value of $J$ when the bandwidth ratio is larger. Dynamical mean-field theory partially confirms these findings, but the intermediate phase at $J=0$ is found to differ from a conventional Mott insulator, with spectral weight extending down to arbitrary low energy. Finally, the orbital-selective Mott phase is found, at zero temperature, to be unstable with respect to an interorbital hybridization $V$ and replaced at small $V$ by a state with a large effective mass (and a low quasiparticle coherence scale) for the narrower band.

arXiv:cond-mat/0503764•Physical Review B•Nov 22, 2005•242 citations

Doping-driven orbital-selective Mott transition in multi-band Hubbard models with crystal field splitting

王义林, 黄理, 杜亮 +1 more

We have studied the doping-driven orbital-selective Mott transition in multi-band Hubbard models with equal band width in the presence of crystal field splitting. Crystal field splitting lifts one of the bands while leaving the others degenerate. We use single-site dynamical mean-field theory combined with continuous time quantum Monte Carlo impurity solver to calculate a phase diagram as a function of total electron filling N and crystal field splitting ?. We find a large region of orbital-selective Mott phase in the phase diagram when the doping is large enough. Further analysis indicates that the large region of orbital-selective Mott phase is driven and stabilized by doping. Such models may account for the orbital-selective Mott transition in some doped realistic strongly correlated materials.

中国物理B：英文版•Jan 1, 2016•0 citations

Correlation-driven Lifshitz transition and orbital order in a two-band Hubbard model

F. Grandi, A. Amaricci, Massimo Capone +1 more

We study by dynamical mean-field theory the ground state of a quarter-filled Hubbard model of two bands with different bandwidths. At half-filling, this model is known to display an orbital selective Mott transition, with the narrower band undergoing Mott localization while the wider one being still itinerant. At quarter-filling, the physical behavior is different and to some extent reversed. The interaction generates an effective crystal field splitting, absent in the Hamiltonian, that tends to empty the narrower band in favor of the wider one, which also become more correlated than the former at odds with the orbital selective paradigm. Upon increasing the interaction, the depletion of the narrower band can continue till it empties completely and the system undergoes a topological Lifshitz transition into a half-filled single-band metal that eventually turns insulating. Alternatively, when the two bandwidths are not too different, a first order Mott transition intervenes before the Lifshitz's one. The properties of the Mott insulator are significantly affected by the interplay between spin and orbital degrees of freedom.

arXiv:1803.08008•Physical review. B./Physical review. B•Jul 2, 2018•5 citations
We study the optical conductivity and orbital susceptibility of the two-orbital Hubbard model within the extended linearized dynamical mean-field theory. In the orbital-selective Mott phase (OSMP), the optical conductivity of the wide band presents a non-zero Drude peak, while the optical conductivity of the narrow band drops to zero in the lower energy region. It is shown that the OSMP is constrained by the negative crystal-field splitting, while it can survive in the region with positive crystal-field splitting. We also find that the orbital susceptibility presents a reversion at Fermi surface in the OSMP regime, which implies that orbital ordering can coexist with OSMP in two-orbital systems.
We investigate the effects of crystal field splitting in a doped two-band Hubbard model with different bandwidths within dynamical mean-field theory (DMFT), using a quantum Monte Carlo impurity solver. In addition to an orbital-selective Mott phase (OSMP) of the narrow band, which is adiabatically connected with the well-studied OSMP in the half-filled case without crystal field splitting, we find, for sufficiently strong interaction and a suitable crystal field, also an OSMP of the wide band. We establish the phase diagram (in the absence of magnetic or orbital order) at moderate doping as a function of interaction strength and crystal field splitting and show that also the wide-band OSMP is associated with non-Fermi-liquid behavior in the case of Ising-type Hund rule couplings. Our numerical results are supplemented by analytical strong-coupling studies of spin order and spectral functions at integer filling.
The effect of interorbital hopping on orbital selective Mottness in a two-band correlation system is investigated by using the dynamical mean-field theory with the Lanczos method as impurity solver. The phase diagrams of the two-orbital Hubbard model with non-local interorbital hopping (t12) , where the orbital selective Mott phases (OSMP) region is expanded by the increasing of the interorbital hopping. We compare the results obtained by self-consistent relations of Bethe lattice and squate lattice based on DMFT procedure, and the general OSMP physics of Bethe lattice is consistent with that of the square lattice while the critical points of two kinds of lattices are different. We extend the method to the study of half-filled Ba2CuO4–δ materials. By comparing with the band structure obtained from the density functional theory (DFT), it is found that the isotropic inter-orbital hopping has a great influence on the bandstructure. The DFT bandstructure in DMFT is considered, and the phase diagram of the material is obtained. The half-filled Ba2CuO4–δ should be orbital-selective Mott compound according to our results.
The effect of interorbital hopping on the orbital selective Mottness in a two-band correlation system is investigated by using the dynamical mean-field theory with the Lanczos method as impurity solver. We construct the phase diagram of the two-orbital Hubbard model with interorbital hopping (t12)t_{12})t12​), where the orbital selective Mott phases (OSMP) show different evolution trends. We find that the negative interorbital hopping (t12<0t_{12}<0t12​<0) can enhance the OSMP regime upon tuning the effective bandwidth ratio. On the contrary, for the cases with positive interorbital hopping (t12>0t_{12}>0t12​>0), the OSMP region becomes narrow with the increase of orbital hybridization until it disappears. It is also shown that a new OSMP emerges for a large enough positive interorbital hopping, owing to the role exchange of wide and narrow effective orbitals caused by the large t12t_{12}t12​. Our results are also applicable to the hole-overdoped Ba2_22​CuO4−δ_{4-δ}4−δ​ superconductor, which is an orbital-selective Mott compound at half-filling.
We examine whether the Mott transition of a half-filled, two-orbital Hubbard model with unequal bandwidths occurs simultaneously for both bands or whether it is a two-stage process in which the orbital with narrower bandwith localizes first (giving rise to an intermediate ``orbital-selective'' Mott phase). This question is addressed using both dynamical mean-field theory and a representation of fermion operators in terms of slave quantum spins, followed by a mean-field approximation (similar in spirit to a Gutzwiller approximation). In the latter approach, the Mott transition is found to be orbital selective for all values of the Coulomb exchange (Hund) coupling JJJ when the bandwidth ratio is small and only beyond a critical value of JJJ when the bandwidth ratio is larger. Dynamical mean-field theory partially confirms these findings, but the intermediate phase at J=0J=0J=0 is found to differ from a conventional Mott insulator, with spectral weight extending down to arbitrary low energy. Finally, the orbital-selective Mott phase is found, at zero temperature, to be unstable with respect to an interorbital hybridization VVV and replaced at small VVV by a state with a large effective mass (and a low quasiparticle coherence scale) for the narrower band.
We have studied the doping-driven orbital-selective Mott transition in multi-band Hubbard models with equal band width in the presence of crystal field splitting. Crystal field splitting lifts one of the bands while leaving the others degenerate. We use single-site dynamical mean-field theory combined with continuous time quantum Monte Carlo impurity solver to calculate a phase diagram as a function of total electron filling N and crystal field splitting ?. We find a large region of orbital-selective Mott phase in the phase diagram when the doping is large enough. Further analysis indicates that the large region of orbital-selective Mott phase is driven and stabilized by doping. Such models may account for the orbital-selective Mott transition in some doped realistic strongly correlated materials.
We study by dynamical mean-field theory the ground state of a quarter-filled Hubbard model of two bands with different bandwidths. At half-filling, this model is known to display an orbital selective Mott transition, with the narrower band undergoing Mott localization while the wider one being still itinerant. At quarter-filling, the physical behavior is different and to some extent reversed. The interaction generates an effective crystal field splitting, absent in the Hamiltonian, that tends to empty the narrower band in favor of the wider one, which also become more correlated than the former at odds with the orbital selective paradigm. Upon increasing the interaction, the depletion of the narrower band can continue till it empties completely and the system undergoes a topological Lifshitz transition into a half-filled single-band metal that eventually turns insulating. Alternatively, when the two bandwidths are not too different, a first order Mott transition intervenes before the Lifshitz's one. The properties of the Mott insulator are significantly affected by the interplay between spin and orbital degrees of freedom.