Competing chiral and multipolar electric phases in the extended Falicov-Kimball model

Zenker, B.; Fehske, Holger; Batista, Cristian D.

doi:10.1103/physrevb.82.165110

Cited by 13 publications

(23 citation statements)

References 30 publications

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“…The weak (U < 1) and strong (V ≪ U and V n ≪ U) coupling limits of the model Hamiltonian H 0 + H V + H n have been analyzed recently by Zenker et al in [23], and the corresponding mean-field quantum phase diagrams were presented as functions of the model parameters U, V, V n and E f for the half-filed band case n f + n d = 1 and D = 2. Moreover, examining effects of the local V and nonlocal V n hybridization they found that in the pseudospin space (c…”

Section: Introductionmentioning

confidence: 99%

“…In the current paper we examine model for arbitrary V and V n and unlike the paper of Zenker et al [23] we focus our attention primarily on a description of process of formation and condensation of exitonic bound states. For this reason we calculate (by the DMRG method) various ground state characteristics of the model such as the excitonic momentum distribution N(q), the density of zero momentum excitons E f .…”

Section: Introductionmentioning

confidence: 99%

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Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

Farkašovský

2017

Solid State Communications

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We study the combined effects of local and nonlocal hybridization on the formation and condensation of the excitonic bound states in the extended FalicovKimball model by the density-matrix-renormalization-group (DMRG) method. Analysing the resultant behaviours of the excitonic momentum distribution N (q) we found, that unlike the local hybridization V , which supports the formation of the q = 0 momentum condensate, the nonlocal hybridization V n supports the formation of the q = π momentum condensate. The combined effect of local and nonlocal hybridization further enhances the excitonic correlations in q = 0 as well as q = π state, especially for V and V n values from the charge-density-wave (CDW) region. Strong effects of local and nonlocal hybridization are observed also for other ground-state quantities of the model such as the f -electron density, or the density of unbound d-electrons, which are generally enhanced with increasing V and V n . The same calculations performed for nonzero values of f -level energy E f revealed that this model can yield a reasonable explanation for the pressure-induced resistivity anomaly observed experimentally in T mSe 0.45 T e 0.55 compound.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

Farkašovský

2017

Solid State Communications

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“…4 Without loss of generality the order parameter ∆ kQ can then be assumed to be real. 20,29 Taking the electron-phonon interaction into account, a possible static lattice distortion (but also the coupling of electrons and holes to dynamical phonons without lattice dimerization) induces a phase fixation and, therefore, give rise to a massive phase mode. Of course, a more complicated form of the electron-electron interaction may also lead to a gapped electron-hole excitation spectrum.…”

Section: Dynamical Electron-phonon Couplingmentioning

confidence: 99%

Fate of the excitonic insulator in the presence of phonons

2014

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The influence of phonons on the formation of the excitonic insulator has hardly been analyzed so far. Recent experiments on Ta2NiSe5, 1T -TiSe2, and TmSe0.45Te0.55, being candidates for realizing the excitonic-insulator state, suggest, however, that the underlying lattice plays a significant role. Employing the Kadanoff-Baym approach we address this issue theoretically. We show that owing to the electron-phonon coupling a static lattice distortion may arise at the excitonic instability. Most importantly such a distortion will destroy the acoustic phase mode being present if the electron-hole pairing and condensation is exclusively driven by the Coulomb interaction. The absence of offdiagonal long-range order, when lattice degrees of freedom are involved, challenges that excitons in these materials form a superfluid condensate of Bose particles or Cooper pairs composed of electrons and holes.

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“…From the theoretical side, the extended FalicovKimball model was considered as a paradigmatic model to describe the EI formation and the closely related phenomenon of electronic ferroelectricity [30][31][32][33][34][35][36][37][38][39][40][41] . Here the spin degrees of freedom were not taken into account, however.…”

Section: Introductionmentioning

confidence: 99%

Competition between excitonic charge and spin density waves: Influence of electron-phonon and Hund's rule couplings

et al. 2015

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We analyze the stability of excitonic ground states in the two-band Hubbard model with additional electron-phonon and Hund's rule couplings using a combination of mean-field and variational cluster approaches. We show that both the interband Coulomb interaction and the electron-phonon interaction will cooperatively stabilize a charge density wave (CDW) state which typifies an "excitonic" CDW if predominantly triggered by the effective interorbital electron-hole attraction or a "phononic" CDW if mostly caused by the coupling to the lattice degrees of freedom. By contrast, the Hund's rule coupling promotes an excitonic spin density wave. We determine the transition between excitonic charge and spin density waves and comment on a fixation of the phase of the excitonic order parameter that would prevent the formation of a superfluid condensate of excitons. The implications for exciton condensation in several material classes with strongly correlated electrons are discussed.

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Competing chiral and multipolar electric phases in the extended Falicov-Kimball model

Cited by 13 publications

References 30 publications

Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

Fate of the excitonic insulator in the presence of phonons

Competition between excitonic charge and spin density waves: Influence of electron-phonon and Hund's rule couplings

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