Superconductivity from repulsive interaction

Maiti, S.; Chubukov, Andrey V.

doi:10.1093/acprof:oso/9780198719267.003.0004

Cited by 16 publications

(21 citation statements)

References 99 publications

(147 reference statements)

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“…This mechanism has been analyzed within RPA [14,15] and within the renormalization group (RG) [16], and was recently re-discovered [17]. The outcome is that, depending on parameters, spin fluctuations either favor s +− SC with the gap changing sign between the inner and the middle d xz /d yz pockets [14,15], or d−wave SC with the gap predominantly residing on the outer d xy pocket [16] Each scenario has a potential to explain superconductivity in KFe 2 As 2 , but the key shortcoming of both is that s−wave and the d−wave attractions are very weak [15] because the mechanism is essentially of Kohn-Luttinger type [18]. Additionally, the d−wave pairing scenario yields the largest gap on the d xy pocket, which is inconsistent with laser ARPES [6].…”

Section: Pacs Numbersmentioning

confidence: 99%

Hund Interaction, Spin-Orbit Coupling, and the Mechanism of Superconductivity in Strongly Hole-Doped Iron Pnictides

Vafek

Chubukov

2017

Phys. Rev. Lett.

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We present a novel mechanism of s−wave pairing in Fe-based superconductors. The mechanism involves holes near dxz/dyz pockets only and is applicable primarily to strongly hole doped materials. We argue that as long as the renormalized Hund's coupling J exceeds the renormalized inter-orbital Hubbard repulsion U ′ , any finite spin-orbit coupling gives rise to s-wave superconductivity. This holds even at weak coupling and regardless of the strength of the intra-orbital Hubbard repulsion U . The transition temperature grows as the hole density decreases. The pairing gaps are four-fold symmetric, but anisotropic, with the possibility of eight accidental nodes along the larger pocket. The resulting state is consistent with the experiments on KFe2As2.

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Section: Pacs Numbersmentioning

confidence: 99%

Hund Interaction, Spin-Orbit Coupling, and the Mechanism of Superconductivity in Strongly Hole-Doped Iron Pnictides

Vafek

Chubukov

2017

Phys. Rev. Lett.

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“…Since we are concerned with the low-density limit, we instead work with the full set of equations, Eqs. (8)(9)(10).…”

Section: Migdal-eliashberg Approximationmentioning

confidence: 99%

The Effect of Repulsion on Superconductivity at Low Density

Phan,

Chubukov

2021

Preprint

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We examine the effect of repulsion on superconductivity in a three-dimensional system with a Bardeen-Pines-like interaction in the low-density limit, where the chemical potential µ is much smaller than the phonon frequency ωL. We parameterize the strength of the repulsion by a dimensionless parameter f , and find that the superconducting transition temperature Tc approaches a nonzero value in the µ = 0 limit as long as f is below a certain threshold f * . In this limit, we find that Tc goes to zero as a power of f * − f , in contrast to the high density limit, where Tc goes to zero exponentially quickly as f approaches f * . For all nonzero f , the gap function ∆(ωm) changes sign along the Matsubara axis, which allows the system to partially overcome the repulsion at high frequencies. We trace the position of the gap node with f and show that it approaches zero frequency as f approaches f * . To investigate the robustness of our conclusions, we then go beyond the Bardeen-Pines model and include full dynamical screening of the interaction, finding that Tc still saturates to a non-zero value at µ = 0 when f < f * .

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“…But they are so complex that researchers are forced to consider them separately in order to find the key concepts and express key ideas explaining the huge totality of experimental data. General discussion and the analysis of high-T c -oxide superconductivity can be found in comprehensive reviews [21,25,42,50,53,65,73,75,78,80,86,89,104]. In particular, the main questions to be solved are as follows: (i) Is superconductivity in cuprates a conventional one based on the Cooper pairing concept?…”

Section: Introductionmentioning

confidence: 99%