Fermi blockade of the strong electron–phonon interaction in modelled optimally doped high temperature superconductors

Mishchenko, A. S.; Tupitsyn, I. S.; Nagaosa, Naoto; Prokof’ev, Nikolay

doi:10.1038/s41598-021-89059-w

Cited by 8 publications

(4 citation statements)

References 46 publications

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“…The MA prediction is that especially at stronger couplings, the mass renormalization reduces significantly and quickly as the concentration of carriers increases. This is in qualitative agreement with 2D results reported recently in figure 1 of [26], which shows an increasing Z(k F ) with increasing E F /Ω at small values of the latter parameter (due to a small concentration x). Those results also show an eventual upturn as the Migdal limit is being reached, but we do not expect that regime to be well described by our variational approximation.…”

Section: Fermi Speed and Effective Mass Renormalizationsupporting

confidence: 93%

“…In this context, it is important to mention that BDMC results for the 2D version of this problem have been recently published [26], so there is hope that 1D results will become available soon either from BDMC and/or from 1D specific numerical methods such as density matrix renormalization group. Taken together, we hope that they will provide a good starting point for understanding the properties of these quasiparticles in this part of the parameter space that lies far from the Migdal limit.…”

Section: Discussionmentioning

confidence: 99%

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Polarons in spinless metals—a variational solution

Berciu

2022

J. Phys. Mater.

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We propose a simple variational solution for calculating one-particle spectral functions in lattice models of spinless metals with strong electron-phonon coupling. It is based on a generalization of the Momentum Average variational approximation for single polarons, combined with the assumption that the other fermions in the system are locked into an inert Fermi sea. We expect the method to be accurate for fermion addition spectral functions in metals with a small Fermi energy (nearly empty band), and for fermion removal spectral functions in metals with a large Fermi energy (nearly full band), provided that the characteristic phonon frequency is not too small. Both these regions are far from the region where the Migdal theorem holds, thus our results oﬀer new insights into polaronic behavior in a largely unexplored part of the parameter space. Here, we show results for the Holstein coupling in one-dimension and present some ways to gauge their accuracy, but ultimately this will need to be veriﬁed against numerical calculations. This variational method can be extended straightforwardly to higher dimensions and other forms of electron-phonon coupling.

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Section: Fermi Speed and Effective Mass Renormalizationsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Polarons in spinless metals—a variational solution

Berciu

2022

J. Phys. Mater.

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“…Furthermore, it is well established that Migdal's approximation fails when E F < Ω. [38] In this Letter we advance the study of electron-addition spectral functions to this unexplored area of the parameter space: low carrier concentrations x ≪ 1 so that E F < Ω, at all couplings. The results presented here are limited to spinless electrons to avoid the possibility of bipolaron formation and/or superconductivity.…”

Section: Introductionmentioning

confidence: 87%

Electron addition spectral functions of low-density polaron liquids

Nocera,

Berciu

2023

SciPost Phys.

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Spectral functions are important quantities that contain a wealth of information about the quasiparticles of a system, and that can also be measured experimentally. For systems with electron-phonon coupling, good approximations for the spectral function are available only in the Migdal limit (at Fermi energies much larger than the typical phonon frequency, E_F\gg \OmegaEF≫Ω, requiring a large carrier concentration xx) and in the single polaron limit (at x=0x=0). Here we show that the region with x\ll 1x≪1(E_F<\OmegaEF<Ω) can also be reliably investigated with the Momentum Average (MA) variational approximation, which essentially describes the formation of a polaron above an inert Fermi sea. Specifically, we show that for the one-dimensional spinless Holstein model, the MA spectral functions compare favorably with those calculated using variationally exact density matrix renormalization group simulations (DMRG) evaluated directly in frequency-space, so long as x<0.1x<0.1 and the adiabaticity ratio \Omega/t>0.5Ω/t>0.5. Unlike in the Migdal limit, here 'polaronic physics’ emerges already at moderate couplings. The relevance of these results for a spinful low-xx metal is also discussed.

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“…The ADiagMC technique lists all diagrams of order N , performs the analytic summation over internal Matsubara frequencies for every listed diagram [13,14], and stochastically samples integrals over internal momenta. The DiagMC approach works directly in the thermodynamic limit [18,19], does not suffer from the conventional notorious fermionic sign problem [20], and can be applied to systems with arbitrary dispersion relations and shapes of the interaction potential [18,19,[21][22][23]. The ADiagMC technique works in the same way.…”

mentioning

confidence: 99%

Dynamic Response of an Electron Gas: Towards the Exact Exchange-Correlation Kernel

LeBlanc¹,

Chen²,

Haule³

et al. 2022

Preprint

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Precise calculations of dynamics in the homogeneous electron gas (jellium model) are of fundamental importance for design and characterization of new materials. We introduce a diagrammatic Monte Carlo technique based on algorithmic Matsubara integration that allows us to compute frequency and momentum resolved finite temperature response directly in the real frequency domain using series of connected Feynman diagrams. The data for charge response at moderate electron density are used to extract the frequency dependence of the exchange-correlation kernel at finite momenta and temperature. These results are as important for development of the time-dependent density functional theory for materials dynamics as ground state energies are for the density functional theory.

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Fermi blockade of the strong electron–phonon interaction in modelled optimally doped high temperature superconductors

Cited by 8 publications

References 46 publications

Polarons in spinless metals—a variational solution

Polarons in spinless metals—a variational solution

Electron addition spectral functions of low-density polaron liquids

Dynamic Response of an Electron Gas: Towards the Exact Exchange-Correlation Kernel

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