The Hubbard-Holstein model

Linden, Wolfgang von der; Berger, E.; Valasek, P.

doi:10.1007/bf00752333

Cited by 15 publications

(12 citation statements)

References 18 publications

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“…It is the situation that is quite suitable for the OF pairing, although only the possibility of the EF pairing has been so far investigated extensively. [43][44][45][46][47][48][49][50][51][52] The purpose of this paper is two folds: (i) to investigate the favorable conditions for the OF pairing in the strong-coupling electron-phonon systems, (ii) to elucidate the properties of the s-wave triplet as the simplest case of the OF pairing. In §2, we give the Holstein-Hubbard model and the formulation for the OF pairing state.…”

Section: Introductionmentioning

confidence: 99%

Possible Odd-Frequency Superconductivity in Strong-Coupling Electron–Phonon Systems

2011

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A possibility of the odd-frequency pairing in the strong-coupling electron-phonon systems is discussed. Using the Holstein-Hubbard model, we demonstrate that the anomalously soft Einstein mode with the frequency ω E ≪ ω c (ω c is the order of the renormalized bandwidth) mediates the s-wave odd-frequency triplet pairing against the ordinary even-frequency singlet pairing. It is necessary for the emergence of the odd-frequency pairing that the pairing interaction is strongly retarded as well as the strong coupling, since the pairing interaction for the odd-frequency pairing is effective only in the diagonal scattering channel, (ω n , −ω n ) → (ω n ′ , −ω n ′ ) with ω n ′ = ω n ω E . Namely, the odd-frequency superconductivity is realized in the opposite limit of the original BCS theory. The Ginzburg-Landau analysis in the strong-coupling region shows that the specific-heat discontinuity and the slope of the temperature dependence of the superfluid density can be quite small as compared with the BCS values, depending on the ratio of the transition temperature T c and ω c .

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Section: Introductionmentioning

confidence: 99%

Possible Odd-Frequency Superconductivity in Strong-Coupling Electron–Phonon Systems

2011

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] For the pure Holstein case, Freericks et al 7,8 found instabilities to charge order and superconductivity by quantum Monte Carlo ͑QMC͒ and iterated perturbation theory for different filling factors. At half-filling, Benedetti and Zeyher, 10 and Hague and D'Ambrumenil, 23 investigated the normal state and found a breakdown of Migdal-Eliashberg theory when a lattice instability develops for stronger electron-phonon coupling.…”

Section: Introductionmentioning

confidence: 99%

Competition between antiferromagnetic and charge order in the Hubbard-Holstein model

Bauer

Hewson

2010

Phys. Rev. B

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Sec. IV. Before that in Sec. III, we discuss the global phase diagram, the order parameters and static quantities and their dependence on U, , and 0 . Section V explores the normal state properties of the HH model which helps to understand the ground-state phase diagram and transition. In Sec. VI we discuss how the bosonic properties are modified by the coupling to the electronic system. In Sec. VII we present results for the electronic and bosonic spectral functions, before concluding in Sec. VIII.

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“…Another possible ordered state occurs when the pairs condense into a superconducting phase. This is expected to occur when the system is doped away from fillings which favor CDW order and has been studied with, for example, Eliashberg theory [40][41][42][43][44][45]. QMC simulations have given indications of pairing as well [46][47][48].…”

Section: Holstein Modelmentioning

confidence: 99%

Electron-Phonon Interactions in Flat Band Systems

Feng,

Scalettar

2020

Preprint

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Existing Quantum Monte Carlo studies have investigated the properties of fermions on a Lieb (CuO2) lattice interacting with an on-site, or near-neighbor electron-electron coupling. Attention has focused on the interplay of such interactions with the macroscopic degeneracy of local zero energy modes, from which Bloch states can be formed to produce a flat band in which energy is independent of momentum. The resulting high density of states, in combination with the Stoner criterion, suggests that there should be pronounced instabilities to ordered phases. Indeed, a theorem by Lieb rigorously establishes the existence of ferrimagnetic order. Here we study the charge density wave phases induced by electron-phonon coupling on the Lieb lattice, as opposed to previous work on electron-electron interactions. Our key result is the demonstration of charge density wave (CDW) phases at one-third and two-thirds fillings, characterized by long-range density density correlations between doubly occupied sites on the minority or majority sublattice, and an accompanying gap. We also compute the transition temperature to the ordered phase as a function of the electron-phonon coupling.

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The Hubbard-Holstein model

Cited by 15 publications

References 18 publications

Possible Odd-Frequency Superconductivity in Strong-Coupling Electron–Phonon Systems

Possible Odd-Frequency Superconductivity in Strong-Coupling Electron–Phonon Systems

Competition between antiferromagnetic and charge order in the Hubbard-Holstein model

Electron-Phonon Interactions in Flat Band Systems

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