Anderson-Hubbard model in infinite dimensions

Ulmke, M.; Janiš, V.; Vollhardt, D.

doi:10.1103/physrevb.51.10411

Cited by 142 publications

(174 citation statements)

References 55 publications

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“…The DMFT can easily be extended to study correlated lattice electrons with local disorder [112][113][114][115][116][117]8]. For this purpose a single-particle term with random local energies i is added to the Hubbard model, leading to the Anderson-Hubbard model…”

Section: Electronic Correlations and Disordermentioning

confidence: 99%

Dynamical Mean-Field Theory

Vollhardt

Byczuk

Kollar

2011

Springer Series in Solid-State Sciences

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Abstract. The dynamical mean-field theory (DMFT) is a widely applicable approximation scheme for the investigation of correlated quantum many-particle systems on a lattice, e.g., electrons in solids and cold atoms in optical lattices. In particular, the combination of the DMFT with conventional methods for the calculation of electronic band structures has led to a powerful numerical approach which allows one to explore the properties of correlated materials. In this introductory article we discuss the foundations of the DMFT, derive the underlying self-consistency equations, and present several applications which have provided important insights into the properties of correlated matter. Motivation Electronic CorrelationsAlready in 1937, at the outset of modern solid state physics, de Boer and Verwey [1] drew attention to the surprising properties of materials with incompletely filled 3d-bands. This observation prompted Mott and Peierls [2] to discuss the interaction between the electrons. Ever since transition metal oxides (TMOs) were investigated intensively [3]. It is now well-known that in many materials with partially filled electron shells, such as the 3d transition metals V and Ni and their oxides, or 4f rare-earth metals such as Ce, electrons occupy narrow orbitals. The spatial confinement enhances the effect of the Coulomb interaction between the electrons, making them "strongly correlated". Correlation effects can lead to profound quantitative and qualitative changes of the physical properties of electronic systems as compared to non-interacting particles. In particular, they often respond very strongly to changes in external parameters. This is expressed by large renormalizations of the response functions of the system, e.g., of the spin susceptibility and the charge compressibility. In particular, the interplay between the spin, charge and orbital degrees of freedom of the correlated d and f electrons and with the lattice degrees of freedom leads to an amazing multitude of ordering phenomena and other fascinating properties, including high temperature superconductivity, colossal magnetoresistance and Mott metal-insulator transitions [3].arXiv:1109.4833v1 [cond-mat.str-el]

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Section: Electronic Correlations and Disordermentioning

confidence: 99%

Dynamical Mean-Field Theory

Vollhardt

Byczuk

Kollar

2011

Springer Series in Solid-State Sciences

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“…To detect a ferromagnetic instability one calculates the temperature dependence of the uniform static susceptibility χ F from the corresponding two-particle correlation function [36]. For N 0 gfcc (E) and at an intermediate interaction strength of U = 4 the ferromagnetic response is found to be strongest around quarter filling (n ≃ 0.5).…”

Section: Frustrated Latticesmentioning

confidence: 99%

Metallic Ferromagnetism — An Electronic Correlation Phenomenon

Vollhardt

Blümer

Held

et al. 2001

Band-Ferromagnetism

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Abstract. New insights into the microscopic origin of itinerant ferromagnetism were recently gained from investigations of electronic lattice models within dynamical meanfield theory (DMFT). In particular, it is now established that even in the one-band Hubbard model metallic ferromagnetism is stable at intermediate values of the interaction U and density n on regular, frustrated lattices. Furthermore, band degeneracy along with Hund's rule couplings is very effective in stabilizing metallic ferromagnetism in a broad range of electron fillings. DMFT also permits one to investigate more complicated correlation models, e.g., the ferromagnetic Kondo lattice model with Coulomb interaction, describing electrons in manganites with perovskite structure. Here we review recent results obtained with DMFT which help to clarify the origin of band-ferromagnetism as a correlation phenomenon.

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“…Since the lattice Dyson equation is most easily formulated in the frequency domain, Fourier transformations (FTs) are needed twice per DMFT self-consistency cycle. Since naive FTs would violate the analytic properties of Green functions and self-energies, all DMFT-QMC codes use either a special transformation 19 or interpolate the discrete QMC data by cubic splines. 5,20 Recently, it was realized 21,22 that natural boundary conditions are not well suited for modeling imaginary-time Green functions and that misfits can be reduced by allowing for non-zero second derivatives of G at the boundaries τ → 0, τ → β.…”

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confidence: 99%

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

2005

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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. PACS numbers: 71.30.+h, 71.10.Fd, 71.27.+a The Mott-Hubbard metal-insulator transition -a nonperturbative correlation phenomenon -has been a subject of fundamental interest in solid state theory for decades. 1 Recently, this field became even more exciting by the discovery 2,3 of a two-step metal-insulator transition in the effective 3-band system Ca 2−x Sr x RuO 4 , for which the name orbital-selective Mott-transition (OSMT) was coined. 4 The Ca 2−x Sr x RuO 4 system was investigated theoretically in detail by Anisimov et al. 4 within the local density approximation (LDA and LDA+U) and within dynamical mean-field theory 5 (DMFT) solved using the non-crossing approximation (NCA). The underlying assumption of a correlation (rather than lattice-distortion) induced OSMT found support in further band structure calculations 6,7 and strong-coupling expansions for the localized electrons in the orbital-selective Mott phase. 8 Microscopic studies of the OSMT usually consider the 2-band Hubbard model H = H 1 + H 2 , wherehopping between nearest-neighbor sites i, j with amplitude t m for orbital m ∈ {1, 2}, intra-and interorbital Coulomb repulsion parametrized by U and U ′ , respectively, and Ising-type Hund's exchange coupling; n imσ = c † imσ c imσ for spin σ ∈ {↑, ↓}. In addition,contains spin-flip and pair-hopping terms (with1 ≡ 2, ↑ ≡↓ etc.). In cubic lattices, the Hamiltonian is invariant under spin rotation, J z = J ⊥ ≡ J; furthermore U ′ = U − 2J. In the following, we refer to H 1 + H 2 in this spin-isotropic case as the J-model and to the simplified Hamiltonian H 1 as the J z -model. Liebsch 9,10,11 questioned the OSMT scenario for Ca 2−x Sr x RuO 4 on the basis of finite-temperature quantum Monte Carlo (QMC) calculations (within DMFT) for the J z -model using J z = U/4, U ′ = U/2, and semielliptic "Bethe" densities of states with a bandwidth ratio W 2 /W 1 = 2. Additional studies using iterative perturbation theory (IPT) 11 seemed 12 to confirm his conclusion of a single Mott transition of both bands at the same critical U -value. Meanwhile, Koga et al. found an OSMT using exact diagonalization (ED), applied to the full J-model, 13 but not for the J z -model. 14 Consequently, the OSMT scenario was attributed to spin-flip and pairhopping processes.Very recently, four preprints appeared, 15,16,17,18 in which the OSMT was investigated in detail within the DMFT framework. Ref. 15 applied the Gutzwiller variational approach and ED to the J-model at...

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Anderson-Hubbard model in infinite dimensions

Cited by 142 publications

References 55 publications

Dynamical Mean-Field Theory

Dynamical Mean-Field Theory

Metallic Ferromagnetism — An Electronic Correlation Phenomenon

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

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