Density waves in strongly correlated quantum chains

Hohenadler, Martin; Fehske, Holger

doi:10.1140/epjb/e2018-90354-7

Cited by 20 publications

(15 citation statements)

References 204 publications

(375 reference statements)

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“…2 as a function of q, in Fig. 3 we consider the corresponding integrated EELS spectra (9) and the phonon spectral weight (19) over the relevant frequency ranges. In particular, aside from the total spectral weight, we have specifically integrated the spectra in two frequency regions.…”

Section: Integrated Spectramentioning

confidence: 99%

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Phenomenology of phonon-plasmon coupled excitations in three dimensional polar materials

Krsnik,

Barišić

2021

Preprint

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Phonon-plasmon coupled excitations in heavily doped polar materials are addressed by examining bare and integrated electron energy loss spectroscopy (EELS) and phonon spectra. Results are obtained in the zero temperature limit for two semiconductors heavily discussed in the literature, namely GaAs and anatase TiO2, characterized by the weak and the moderate electron-phonon interaction (EPI), respectively. The most prominent spectral features are identified, not only as a function of the electron density that defines the adiabaticity parameter, yet also from the perspective of the EPI strength. In particular, while the adiabaticity parameter undoubtedly governs collective excitations' dispersions, our findings show that the EPI strength profoundly affects the damping of collective excitations within the electron-hole continuum and the distribution of the spectral weight in both the EELS and the phonon spectra. For the weak EPI, the phonon-like excitation is generally well defined and the total EELS spectral weight is redistributed roughly equally among two excitations in the antiadiabatic and the resonant regime. On contrary, in these two regimes, when the EPI is stronger there exist no well-defined collective excitations in a broad range of momenta of the order of magnitude of the Fermi wave vector, with the damping being enhanced by the increasing plasmonic character of excitations. Furthermore, the EELS spectral weight is dominated by the higher frequency excitation, allowing for an experimental estimate of the EPI strength even when the energy resolution is limited. The stronger EPI is accompanied by the large additional phonon spectral weight unambiguously attributed to the lower frequency excitation. In the adiabatic regime, this additional phonon spectra weight is a consequence of the phonon softening effects, while in the antiadiabatic regime it arises due to the virtual cloud of phonons that accompanies the plasma oscillations.

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Section: Integrated Spectramentioning

confidence: 99%

“…Peculiar effects of the EPI are also prominent in systems with high electron densities. In metals, for instance, the EPI may result in a transition to a conventional BCS superconducting [6] or a charge density wave state [7][8][9]. Influences of the EPI are noticeable in spectral features of heavily doped semiconductors as well.…”

Section: Introductionmentioning

confidence: 99%

Phenomenology of phonon-plasmon coupled excitations in three dimensional polar materials

Krsnik,

Barišić

2021

Preprint

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“…The equilibrium phases of the Hubbard-Holstein model have been studied using different methods. Early studies have examined the equilibrium properties of the 1D HH model, using ED with optimized phonon basis 26,45 , local Lang-Firsov transformation 29 , QMC 32,[46][47][48] , DMRG [49][50][51] , cluster perturbation theory 27 , and density-matrix embedding method 52 . The common results indicated CDW/AFM competition on either side of the anti-adiabatic limit u = 2λ and an intermediate regime between the ordered phases.…”

Section: Equilibrium Properties Of the Hubbard-holstein Modelmentioning

confidence: 99%

Zero-Temperature Phases of the 2D Hubbard-Holstein Model: A Non-Gaussian Exact Diagonalization Study

Wang,

Esterlis,

Shi

et al. 2019

Preprint

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We propose a novel numerical method which embeds the variational non-Gaussian wavefunction approach with exact diagonalization, allowing for efficient treatment of correlated systems with both electron-electron and electron-phonon interactions. Using a generalized polaron transformation, we construct a variational wavefunction that absorbs entanglement between electrons and phonons into a variational non-Gaussian transformation; exact diagonalization is then used to treat the electronic part of the wavefunction exactly, thus taking into account high-order correlation effects beyond the Gaussian level. Keeping the full electronic Hilbert space, the complexity is increased only by a polynomial scaling factor relative to the exact diagonalization calculation for pure electrons.As an example, we use this method to study ground-state properties of the two-dimensional Hubbard-Holstein model, providing evidence for the existence of intervening phases between the spin and charge-ordered states. In particular, we find one of the intervening phases has strong charge susceptibility and binding energy, but is distinct from a CDW-ordered state; while the other intervening phase displays superconductivity at weak couplings. This method, as a general framework, can be extended to treat excited states and dynamics, as well as a wide range of systems with both electron-electron and electron-boson interactions.

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“…This model was vastly studied in onedimensional systems, with well-known phase diagrams presenting spin-density wave, bond-order-wave, CDW, and also metallic or phase separation behavior [24][25][26][27][28][29][30][31][32][33]. A remarkable feature in 1D systems is the occurrence of a quantum phase transition from a metallic Luther-Emery liquid phase to a CDW insulator at a finite critical e-ph coupling, in the limit case of the pure Holstein model (U = 0), despite of the FSN [34,35]. By contrast, the properties of the HHM in two-dimensional systems are not entirely clear, even for simple geometries, such as the square lattice.…”

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confidence: 99%

Phase diagram of the two-dimensional Hubbard-Holstein model: enhancement of $s$-wave pairing between charge and magnetic orders

Costa,

Seki,

Yunoki

et al. 2019

Preprint

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We investigate the role of electron-electron and electron-phonon interactions in strongly correlated systems by performing unbiased quantum Monte Carlo simulations in the square lattice Hubbard-Holstein model at half-filling. We study the competition and interplay between antiferromagnetism (AFM) and charge-density wave (CDW), establishing its very rich phase diagram. In the region between AFM and CDW phases, we have found an enhancement of superconducting pairing correlations, favouring (nonlocal) s-wave pairs. Our study sheds light over past inconsistencies in the literature, in particular the emergence of CDW in the pure Holstein model case.

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Density waves in strongly correlated quantum chains

Cited by 20 publications

References 204 publications

Phenomenology of phonon-plasmon coupled excitations in three dimensional polar materials

Phenomenology of phonon-plasmon coupled excitations in three dimensional polar materials

Zero-Temperature Phases of the 2D Hubbard-Holstein Model: A Non-Gaussian Exact Diagonalization Study

Phase diagram of the two-dimensional Hubbard-Holstein model: enhancement of $s$-wave pairing between charge and magnetic orders

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