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

arXiv:1105.4913

Effect of Spin Correlations on Multi-orbital Metal-Insulator Transitions and Suppression of Orbital Selective Mott Transitions

Ya‐Min Quan, Liang‐Jian Zou, Hai‐Qing Lin

Published May 25, 2011• 0 citations
arXivHTMLPDF

Abstract

We present the influence of spin correlation on the metal-insulator transitions (MIT) in two-orbital Hubbard models by the Kotliar-Ruckenstein slave-boson approach. In the asymmetric half-filling situation, the two orbits simultaneously transit from conducting to insulating states with the increase of Coulomb correlation, accompanied by a paramagnetic (PM)-antiferromagnetic (AFM) transition. The orbital selective Mott transition found in the PM condition is completely suppressed over a wide correlation range, though it may exist in the systems away from half-filling. In the insulating state, the system crosses over from a partially-polarized spin-gapped phase in the intermediate correlation regime to an almost fully-polarized Mott insulating phase in the strong correlation regime. These results demonstrate that the spin modulation to the quasiparticle spectra brings much rich and more interesting MIT scenario in multi-orbital correlated systems.

DOI
10.48550/arxiv.1105.4913

Related papers

Mott metal-insulator transition in the half-filled Hubbard model on the triangular lattice

Massimo Capone, Luca Capriotti, Federico Becca +1 more

We investigate the metal-insulator transition in the half-filled Hubbard model on the two-dimensional triangular lattice using both the Kotliar-Ruckenstein slave-boson technique and an exact numerical diagonalization of finite clusters. Contrary to the case of a square lattice, where a perfect nesting of the Fermi surface leads to a metal-insulator transition at arbitrarily small values of U, always accompanied by antiferromagnetic ordering, on a triangular lattice, due to the lack of perfect nesting, the transition takes place at a finite value of U, and frustration induces a nontrivial competition among different magnetic phases. Indeed, within the mean-field approximation in the slave-boson approach, as the interaction grows the paramagnetic metal turns into a metallic phase with incommensurate spiral ordering. Increasing the interaction further, a linear spin-density wave is stabilized, and finally for strong coupling the latter phase undergoes a first-order transition toward an antiferromagnetic insulator. No trace of the intermediate phases is seen in the exact diagonalization results, indicating a transition between a paramagnetic metal and an antiferromagnetic insulator.

arXiv:cond-mat/0006437•Physical review. B, Condensed matter•Feb 2, 2001•51 citations

Effects of interorbital hopping on orbital fluctuations and metal-insulator transitions: Extended linearized dynamical mean-field theory

Yun Song, Liang‐Jian Zou

We study the effects of interorbital hopping on orbital fluctuations and Mott-Hubbard metal-insulator transition (MIT) in the two-orbital Hubbard model within the extended linearized dynamical mean-field theory. By mapping the model onto an effective model with different bandwidths through the canonical transformation, we find that at half-filling, the increases of the interorbital Coulomb interaction ${U}^{\ensuremath{'}}$ and the Hund's coupling $J$ drive the MIT, and the critical ${J}_{c}$ for MIT increases with the lift of the interorbital hopping integral ${t}_{ab}$. Meanwhile at quarter filling and in the strong correlation regime, the system without ${t}_{ab}$ exhibits MIT with the decreasing of $J$, and favors the orbital liquid ground state. However, the system transits from metal to insulator with the increasing of ${t}_{ab}$, accompanied with the rising of the orbital order parameter. These results show the important role of the interorbital hopping in the orbital fluctuation and orbital ordering.

arXiv:cond-mat/0504420•Physical Review B•Aug 9, 2005•23 citations

Metal-Mott Insulator Transition and Spin Exchange of Two-Component Fermi Gas with Spin-Orbit Coupling in Two-Dimension Square Optical Lattices

Beibing Huang, Shaolong Wan

Effects of spin-orbit coupling (SOC) on metal-Mott insulator transition (MMIT) and spin exchange physics (SEP) of two-component Fermi gases in two-dimension half-filling square optical lattices are investigated. In the frame of Kotliar and Ruckenstein slave boson and the second order perturbation theory, the phase boundary of paramagnetic MMIT and spin exchange Hamiltonian are calculated. In addition by adopting two mean-field ansatzs including antiferromagnetic, ferromagnetic and spiral phases, we find that SOC can drive a quantum phase transition from antiferromagnet to spiral phase.

arXiv:1107.4213•Jul 21, 2011•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

Suppression of Mott-Hubbard states and metal-insulator transitions in the two-band Hubbard model

Hague, J. P.

I investigate band and Mott insulating states in a two-band Hubbard model, with the aim of understanding the differences between the idealised one-orbital model and the more realistic multi-band case. Using a projection ansatz I show that additional orbitals suppress the metal-insulator transition, leading to a critical coupling of approximately eight times the bare band-width. I also demonstrate the effects of orbital ordering, which hinder Mott-Hubbard states and open a band gap. Since multi-band correlations are common in real materials, this work suggests that the existence of very strongly correlated band insulators may be more common than Mott-Hubbard insulators.

•Jan 1, 2005•1 citation

Suppression of Mott–Hubbard states and metal–insulator transitions in the two-band Hubbard model

J P Hague

I investigate band and Mott insulating states in a two-band Hubbard model, with the aim of understanding the differences between the idealised one-orbital model and the more realistic multi-band case. Using a projection ansatz I show that additional orbitals suppress the metal-insulator transition, leading to a critical coupling of approximately eight times the bare band-width. I also demonstrate the effects of orbital ordering, which hinder Mott-Hubbard states and open a band gap. Since multi-band correlations are common in real materials, this work suggests that the existence of very strongly correlated band insulators may be more common than Mott-Hubbard insulators.

arXiv:cond-mat/0702643•Journal of Physics Condensed Matter•Feb 12, 2005•0 citations
We present the influence of spin correlation on the metal-insulator transitions (MIT) in two-orbital Hubbard models by the Kotliar-Ruckenstein slave-boson approach. In the asymmetric half-filling situation, the two orbits simultaneously transit from conducting to insulating states with the increase of Coulomb correlation, accompanied by a paramagnetic (PM)-antiferromagnetic (AFM) transition. The orbital selective Mott transition found in the PM condition is completely suppressed over a wide correlation range, though it may exist in the systems away from half-filling. In the insulating state, the system crosses over from a partially-polarized spin-gapped phase in the intermediate correlation regime to an almost fully-polarized Mott insulating phase in the strong correlation regime. These results demonstrate that the spin modulation to the quasiparticle spectra brings much rich and more interesting MIT scenario in multi-orbital correlated systems.
We investigate the metal-insulator transition in the half-filled Hubbard model on the two-dimensional triangular lattice using both the Kotliar-Ruckenstein slave-boson technique and an exact numerical diagonalization of finite clusters. Contrary to the case of a square lattice, where a perfect nesting of the Fermi surface leads to a metal-insulator transition at arbitrarily small values of U, always accompanied by antiferromagnetic ordering, on a triangular lattice, due to the lack of perfect nesting, the transition takes place at a finite value of U, and frustration induces a nontrivial competition among different magnetic phases. Indeed, within the mean-field approximation in the slave-boson approach, as the interaction grows the paramagnetic metal turns into a metallic phase with incommensurate spiral ordering. Increasing the interaction further, a linear spin-density wave is stabilized, and finally for strong coupling the latter phase undergoes a first-order transition toward an antiferromagnetic insulator. No trace of the intermediate phases is seen in the exact diagonalization results, indicating a transition between a paramagnetic metal and an antiferromagnetic insulator.
We study the effects of interorbital hopping on orbital fluctuations and Mott-Hubbard metal-insulator transition (MIT) in the two-orbital Hubbard model within the extended linearized dynamical mean-field theory. By mapping the model onto an effective model with different bandwidths through the canonical transformation, we find that at half-filling, the increases of the interorbital Coulomb interaction ${U}^{\ensuremath{'}}$ and the Hund's coupling JJJ drive the MIT, and the critical Jc{J}_{c}Jc​ for MIT increases with the lift of the interorbital hopping integral tab{t}_{ab}tab​. Meanwhile at quarter filling and in the strong correlation regime, the system without tab{t}_{ab}tab​ exhibits MIT with the decreasing of JJJ, and favors the orbital liquid ground state. However, the system transits from metal to insulator with the increasing of tab{t}_{ab}tab​, accompanied with the rising of the orbital order parameter. These results show the important role of the interorbital hopping in the orbital fluctuation and orbital ordering.
Effects of spin-orbit coupling (SOC) on metal-Mott insulator transition (MMIT) and spin exchange physics (SEP) of two-component Fermi gases in two-dimension half-filling square optical lattices are investigated. In the frame of Kotliar and Ruckenstein slave boson and the second order perturbation theory, the phase boundary of paramagnetic MMIT and spin exchange Hamiltonian are calculated. In addition by adopting two mean-field ansatzs including antiferromagnetic, ferromagnetic and spiral phases, we find that SOC can drive a quantum phase transition from antiferromagnet to spiral phase.
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.
I investigate band and Mott insulating states in a two-band Hubbard model, with the aim of understanding the differences between the idealised one-orbital model and the more realistic multi-band case. Using a projection ansatz I show that additional orbitals suppress the metal-insulator transition, leading to a critical coupling of approximately eight times the bare band-width. I also demonstrate the effects of orbital ordering, which hinder Mott-Hubbard states and open a band gap. Since multi-band correlations are common in real materials, this work suggests that the existence of very strongly correlated band insulators may be more common than Mott-Hubbard insulators.
I investigate band and Mott insulating states in a two-band Hubbard model, with the aim of understanding the differences between the idealised one-orbital model and the more realistic multi-band case. Using a projection ansatz I show that additional orbitals suppress the metal-insulator transition, leading to a critical coupling of approximately eight times the bare band-width. I also demonstrate the effects of orbital ordering, which hinder Mott-Hubbard states and open a band gap. Since multi-band correlations are common in real materials, this work suggests that the existence of very strongly correlated band insulators may be more common than Mott-Hubbard insulators.