Interplay of electron–phonon interaction and strong correlations: the possible way to high-temperature superconductivity

Kulić, Miodrag L.

doi:10.1016/s0370-1573(00)00008-9

Cited by 189 publications

(311 citation statements)

References 336 publications

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“…The interaction between electrons and various boson collective modes in a solid manifests itself in many physical observables, such as superconductivity [1][2][3], thermal conductance at interfaces [4], energy relaxation in nano-particles [5], colossal magnetoresistance in ferromagnets [6], charge density wave formation in metals [7], and the Seebeck coefficients in nanoscale junctions [8]. Electron-phonon coupling (EPC), or electron-boson coupling in general, is becoming more important as the community investigates the functionality of complex materials such as electron correlated transition metal compounds, artificially structure thin films, and nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Electron-phonon coupling in a system with broken symmetry: Surface ofBe(0001)

Chien

et al. 2015

Phys. Rev. B

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The momentum-resolved Eliashberg function (ELF), , , for the Be(0001) zone-center surface state was extracted from the high-quality angle-resolved photoemission spectroscopy (ARPES) data at the Fermi energy in the Γ direction, displaying ten peaks. A comparison of the peaks in the ELF to the bulk phonon density of states (DOS) and the bulk and surface phonon dispersion allows for an identification of the origin of all but two of the peaks. The five high energy peaks (> 52 meV) are associated with the coupling of the surface state to bulk phonon modes. The peaks at 44.5 meV and at 49.0 meV have contributions from both the bulk and surface phonons. The most intense peak at 37.5 meV is evidently having contribution from EPC of the surface state to the surface Rayleigh phonon mode. Surprisingly, the two lowest energy modes, which must be associated with surface Rayleigh phonon, cannot be attributed to a high phonon DOS at the surface nor to any Fermi surface nesting. After detail analysis, the three lowest energy peaks are associated with momentum dependence in the EPC matrix, reflected in the phonon line-width changes. As a result of the broken symmetry at the surface, coupling of the initial surface state due to the presence of the surface phonons contributes ~48.5±12.5% of the spectral weight in the ELF and ~6 6.5±10.5% to the mass enhancement ( ).

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Section: Introductionmentioning

confidence: 99%

Electron-phonon coupling in a system with broken symmetry: Surface ofBe(0001)

Chien

et al. 2015

Phys. Rev. B

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“…This feature was investigated in the past by means of analytical techniques based on slave-bosons or X-operators. 4,5,6,7 The assumption of forward scattering predominance within an el-ph framework was shown to explain in a natural way several anomalous properties of cuprates as the difference between transport and superconducting el-ph coupling constants, 6 the linear temperature behaviour of the resistivity, 8 the d-wave symmetry of the superconducting gap. 7,9 Small q scattering selection was shown moreover to be responsible in a natural way for high-T c superconductivity within the context of the nonadiabatic superconductivity.…”

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confidence: 99%

Charge fluctuations and electron-phonon interaction in the finite-UHubbard model

2004

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In this paper we employ a gaussian expansion within the finite-U slave-bosons formalism to investigate the momentum structure of the electron-phonon vertex function in the Hubbard model as function of U and n. The suppression of large momentum scattering and the onset a small-q peak structure, parametrized by a cut-off qc, are shown to be essentially ruled by the band narrowing factor ZMF due to the electronic correlation. A phase diagram of ZMF and qc in the whole U -n space is presented. Our results are in more than qualitative agreement with a recent numerical analysis and permit to understand some anomalous features of the Quantum Monte Carlo data.PACS numbers: 71.10. Fd,71.27.+a,71.45.Lr In the past months a variety of experiments have pointed out an important role of the electron-phonon (el-ph) interaction in many physical properties of the cuprates. 1,2,3 These recent findings have triggered a renewed interest for a theoretical understanding of the elph properties in strongly correlated systems.One of the most remarkable effects of the strong electronic correlation on the el-ph properties is a to favor forward (small q) scattering in the electron-phonon vertex, q being the exchanged phonon momentum. This feature was investigated in the past by means of analytical techniques based on slave-bosons or X-operators. 4,5,6,7 The assumption of forward scattering predominance within an el-ph framework was shown to explain in a natural way several anomalous properties of cuprates as the difference between transport and superconducting el-ph coupling constants, 6 the linear temperature behaviour of the resistivity, 8 the d-wave symmetry of the superconducting gap. 7,9 Small q scattering selection was shown moreover to be responsible in a natural way for high-T c superconductivity within the context of the nonadiabatic superconductivity. 10 So far, this important feature was analyzed only by means of analytical approaches in the U = ∞ limit and a definitive confirm of it based on numerical methods was lacking. The charge response at finite U was addressed in Refs. 11,12, which however focused only on q = 0 susceptibilities. With these motivations in a recent paper Huang et al have addressed this issue in the twodimensional Hubbard model with generic U by using Quantum Monte Carlo (QMC) techniques on a 8×8 cluster. 13 Their results provide a good agreement with the previous analytical studies and represent an important contribution to assess the relevance of el-ph interaction in correlated system.In this paper we employ the slave-boson techniques to investigate the evaluation of the momentum structure of the el-ph vertex interaction as function of the Hubbard repulsion U . While the previous analytical studies were limited to the U = ∞ limit, 4,5,6,7 we were able in this way to evaluate the small momenta selection in the whole phase diagram of parameters U -n, where n is the electron filling. In particular we show that the predominance of small q scattering is strongly dependent on the closeness of the system to t...

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“…In fullerene compounds, the strong electronic correlation favours the small q momentum el-ph coupling [v F q/ω < ∼ 1] [20] probing therefore the positive part of the vertex function P .…”

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confidence: 99%

HighTcSuperconductivity inMgB2by Nonadiabatic Pairing

et al. 2002

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The evidence for the key role of the σ bands in the electronic properties of MgB2 points to the possibility of nonadiabatic effects in the superconductivity of these materials. These are governed by the small value of the Fermi energy due to the vicinity of the hole doping level to the top of the σ bands. We show that the nonadiabatic theory leads to a coherent interpretation of Tc = 39 K and the boron isotope coefficient αB = 0.30 without invoking very large couplings and it naturally explains the role of the disorder on Tc. It also leads to various specific predictions for the properties of MgB2 and for the material optimization of these type of compounds.

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Interplay of electron–phonon interaction and strong correlations: the possible way to high-temperature superconductivity

Cited by 189 publications

References 336 publications

Electron-phonon coupling in a system with broken symmetry: Surface ofBe(0001)

Electron-phonon coupling in a system with broken symmetry: Surface ofBe(0001)

Charge fluctuations and electron-phonon interaction in the finite-UHubbard model

HighTcSuperconductivity inMgB2by Nonadiabatic Pairing

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