Calculations of the superconducting critical temperature with vertex corrections

Kostur, Vladimir N.; Mitrović, B.

doi:10.1103/physrevb.50.12774

Cited by 36 publications

(52 citation statements)

References 21 publications

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“…24, may need to be included since they can enhance T c in the perturbative regime when the e-ph interaction is peaked at small momentum transfers. [48][49][50] Our DFT results hint that FeSe/STO is in this regime providing that a finite integrated coupling strength from the forwardfocused coupling of the oxygen mode can be obtained with an improved method. Another reason why the e-ph interactions might be underestimated in our simulations is that we only considered one STO layer instead of a semi-infinite number of STO layers.…”

Section: Discussionmentioning

confidence: 92%

Ab initiostudy of cross-interface electron-phonon couplings in FeSe thin films onSrTiO3andBaTiO3

et al. 2016

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We study the electron-phonon coupling strength near the interface of monolayer and bilayer FeSe thin films on SrTiO3, BaTiO3, and oxygen-vacant SrTiO3 substrates, using ab initio methods. The calculated total electron-phonon coupling strength λ = 0.2-0.3 cannot account for the high Tc ∼ 70 K observed in these systems through the conventional phonon-mediated pairing mechanism. In all of these systems, however, we find that the coupling constant of a polar oxygen branch peaks at q = 0 with negligible coupling elsewhere, while the energy of this mode coincides with the offset energy of the replica bands measured recently by angle-resolved photoemission spectroscopy experiments. But the integrated coupling strength for this mode from our current calculations is still too small to produce the observed high Tc, even through the more efficient pairing mechanism provided by the forward scattering. We arrive at the same qualitative conclusion when considering a checkerboard antiferromagnetic configuration in the Fe layer. In light of the experimental observations of the replica band feature and the relatively high Tc of FeSe monolayers on polar substrates, our results point towards a cooperative role for the electron-phonon interaction, where the crossinterface interaction acts in conjunction with a purely electronic interaction. We also discuss a few scenarios where the coupling strength obtained here may be enhanced.

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Section: Discussionmentioning

confidence: 92%

Ab initiostudy of cross-interface electron-phonon couplings in FeSe thin films onSrTiO3andBaTiO3

et al. 2016

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“…Ref. 28 , which considered the effect of the vertex corrections on T c not only for an isotropic EPI, but also for spin (antiferromagnetic) fluctuations with a pronounced scattering at the wave vector Q * = (π, π). In the paper 28 the authors used the following equations for the self-energy…”

Section: Kostur and Mitrović's Approximationmentioning

confidence: 99%

“…28 . For an isotropic EPI and a three-dimensional spherical Fermi-surface it is approximated by its value on the…”

Section: Kostur and Mitrović's Approximationmentioning

confidence: 99%

“…In the lowest approximation, the first correction to the unity vertex is determined by the diagram in Fig.1. Then with the obtained vertex function the self-energy Σ is calculated 10,11,28,16 . This traditional method does not allow to take into account higher-order diagrams analytically because of complexity of the integration over momenta.…”

Section: Introductionmentioning

confidence: 99%

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Nonadiabatic contribution to the quasiparticle self-energy in systems with strong electron-phonon interaction

Danylenko

Dolgov

2001

Phys. Rev. B

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We investigate effects of a nonadiabatic electron-phonon(boson) interaction on the quasiparticle self-energy in the lowest order in the coupling constant.Existing approaches either overestimate, or underestimate these effects because of different approximations for momentum and frequency dependences of the vertex corrections. The connection between the nonadiabaticity and a possible instability of the interacting Fermi system is discussed as well.

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“…Kostur and Mitrovic (1993) studied the vertex corrections with the emphasis on two-dimensional systems and Krishnamurthy et al (1994) and Cappelluti and Pietronero (1996) studied systems with a van Hove singularity. Kostur and Mitrovic (1994) studied the corrections to T c from vertex corrections for several model interactions. For a BCS-type of interaction and an isotropic electron-phonon interaction, they found that vertex corrections reduce T c , while for a highly anisotropic interaction, inspired by the cuprate superconductors, they found that T c can also be enhanced by the vertex corrections.…”

Section: Beyond the Migdal-eliashberg Theory A Migdal's Theoremmentioning

confidence: 99%

Superconductivity in fullerides

1997

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Experimental studies of superconductivity properties of fullerides are briefly reviewed. Theoretical calculations of the electron-phonon coupling, in particular for the intramolecular phonons, are discussed extensively. The calculations are compared with coupling constants deduced from a number of different experimental techniques. It is discussed why the A 3 C 60 are not Mott-Hubbard insulators, in spite of the large Coulomb interaction. Estimates of the Coulomb pseudopotential µ * , describing the effect of the Coulomb repulsion on the superconductivity, as well as possible electronic mechanisms for the superconductivity are reviewed. The calculation of various properties within the Migdal-Eliashberg theory and attempts to go beyond this theory are described.

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Calculations of the superconducting critical temperature with vertex corrections

Cited by 36 publications

References 21 publications

Ab initiostudy of cross-interface electron-phonon couplings in FeSe thin films onSrTiO3andBaTiO3

Ab initiostudy of cross-interface electron-phonon couplings in FeSe thin films onSrTiO3andBaTiO3

Nonadiabatic contribution to the quasiparticle self-energy in systems with strong electron-phonon interaction

Superconductivity in fullerides

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