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:cond-mat/0505106 · Physical Review B

Orbital-selective Mott transitions in the anisotropic two-band Hubbard model at finite temperatures

C. Knecht, Nils Blümer, P. G. J. van Dongen

Published Aug 31, 2005• 71 citations
arXivHTMLPDF

Abstract

The anisotropic degenerate two-orbital Hubbard model is studied within dynamical mean-field theory at low temperatures. High-precision calculations on the basis of a refined quantum Monte Carlo (QMC) method reveal that two distinct orbital-selective Mott transitions occur for a bandwidth ratio of 2, even in the absence of spin-flip contributions to the Hund exchange. The second transition---not seen in earlier studies using QMC, iterative perturbation theory, and exact diagonalization---is clearly exposed in a low-frequency analysis of the self-energy and in local spectra.

DOI
10.1103/physrevb.72.081103

Related papers

Orbital‐selective Mott transitions in the 2‐band Jz‐model: a high‐precision quantum Monte Carlo study

P. G. J. van Dongen, C. Knecht, N. Blümer

Abstract Using high‐precision quantum Monte Carlo (QMC) simulations within the framework of dynamical mean field theory (DMFT), we show that the anisotropic degenerate two‐orbital Hubbard model contains two consecutive orbital‐selective Mott transitions (OSMTs) even in the absence of spin‐flip terms and pair‐hopping processes. In order to reveal the second transition we carefully analyze the low‐frequency part of the self‐energy and the local spectral functions. This paper extends our previous work to lower temperatures. We discuss the nature – in particular the order – of both Mott transitions and list various possible extensions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

arXiv:cond-mat/0507682•physica status solidi (b)•Nov 24, 2005•12 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

Orbital-selective Mott transitions in a doped two-band Hubbard model

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

We extend previous studies on orbital-selective Mott transitions in the paramagnetic state of the half-filled degenerate two-band Hubbard model to the general doped case, using a high-precision quantum Monte Carlo dynamical mean-field theory solver. For sufficiently strong interactions, orbital-selective Mott transitions as a function of total band filling are clearly visible in the band-specific fillings, quasiparticle weights, double occupancies, and spectra. The results are contrasted with those of single-band models for similar correlation strengths.

arXiv:0906.2966•Physical Review B•Sep 9, 2009•28 citations

Reply to "Comment on `Orbital-selective Mott transitions in the anisotropic two-band Hubbard model at finite temperatures'"

C. Knecht, Nils Blümer, P. G. J. van Dongen

In a Comment [cond-mat/0506138] on our recent e-print [cond-mat/0505106] Liebsch claimed "excellent correspondence" between our high-precision quantum Monte-Carlo (QMC) data for the anisotropic two-band Hubbard model with Ising type exchange couplings and his earlier QMC results. Liebsch also claimed that the sequence of two orbital-selective Mott transitions, identified by us in this model, had already been reported in his earlier work. Here we demonstrate that both claims are incorrect. We establish that Liebsch's previous QMC estimates for the quasiparticle weight Z have relative errors exceeding 100% near transitions and cannot be used to infer the existence of a second Mott transition (for U_{c2}~2.5). We further show that Liebsch's attribution of our findings to his own earlier work is disproved by the published record. Consequently, the Comment is unwarranted; all results and formulations of our e-print remain valid.

arXiv:cond-mat/0506450•Jun 17, 2005•0 citations

Novel Mott Transitions in a Nonisotropic Two-Band Hubbard Model

A. Liebsch

The Mott transition in a two-band Hubbard model involving subbands of different widths is studied as a function of temperature using dynamical mean field theory combined with exact diagonalization. The phase diagram is shown to exhibit two successive first-order transitions if the full Hund's rule coupling is included. In the absence of spin-flip and pair-exchange terms the lower transition remains first-order while the upper becomes continuous.

arXiv:cond-mat/0505393•Physical Review Letters•Sep 8, 2005•92 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.

arXiv:cond-mat/0504040•Physical Review B•Nov 29, 2005•79 citations
The anisotropic degenerate two-orbital Hubbard model is studied within dynamical mean-field theory at low temperatures. High-precision calculations on the basis of a refined quantum Monte Carlo (QMC) method reveal that two distinct orbital-selective Mott transitions occur for a bandwidth ratio of 2, even in the absence of spin-flip contributions to the Hund exchange. The second transition---not seen in earlier studies using QMC, iterative perturbation theory, and exact diagonalization---is clearly exposed in a low-frequency analysis of the self-energy and in local spectra.
Abstract Using high‐precision quantum Monte Carlo (QMC) simulations within the framework of dynamical mean field theory (DMFT), we show that the anisotropic degenerate two‐orbital Hubbard model contains two consecutive orbital‐selective Mott transitions (OSMTs) even in the absence of spin‐flip terms and pair‐hopping processes. In order to reveal the second transition we carefully analyze the low‐frequency part of the self‐energy and the local spectral functions. This paper extends our previous work to lower temperatures. We discuss the nature – in particular the order – of both Mott transitions and list various possible extensions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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 extend previous studies on orbital-selective Mott transitions in the paramagnetic state of the half-filled degenerate two-band Hubbard model to the general doped case, using a high-precision quantum Monte Carlo dynamical mean-field theory solver. For sufficiently strong interactions, orbital-selective Mott transitions as a function of total band filling are clearly visible in the band-specific fillings, quasiparticle weights, double occupancies, and spectra. The results are contrasted with those of single-band models for similar correlation strengths.
In a Comment [cond-mat/0506138] on our recent e-print [cond-mat/0505106] Liebsch claimed "excellent correspondence" between our high-precision quantum Monte-Carlo (QMC) data for the anisotropic two-band Hubbard model with Ising type exchange couplings and his earlier QMC results. Liebsch also claimed that the sequence of two orbital-selective Mott transitions, identified by us in this model, had already been reported in his earlier work. Here we demonstrate that both claims are incorrect. We establish that Liebsch's previous QMC estimates for the quasiparticle weight Z have relative errors exceeding 100% near transitions and cannot be used to infer the existence of a second Mott transition (for U_{c2}~2.5). We further show that Liebsch's attribution of our findings to his own earlier work is disproved by the published record. Consequently, the Comment is unwarranted; all results and formulations of our e-print remain valid.
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.