Robust determination of the superconducting gap sign structure via quasiparticle interference

Hirschfeld, P. J.; Altenfeld, D.; Eremin, I.; Mazin, I. I.

doi:10.1103/physrevb.92.184513

Cited by 76 publications

(92 citation statements)

References 40 publications

(47 reference statements)

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“…for a weak scatterer, and the structure of this result is universal in the sense that it does not depend qualitatively on the strength of the scattering and the details of the electronic structure 24 . Here ∆ 1 and ∆ 2 are the two gaps associated with the two bands, U is a scalar scattering potential, A represents an area in q-space containing gap-sign-changing scattering vectors, and ρ(q, E) represents the FT-QPI, which is the FT of the spatial map of the differential conductivity g (r, E).…”

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confidence: 78%

“…Probes based on Josephson loops with π-contacts, instead of providing a qualitative test, offer only a quantitative probe, since all possible junctions have currents arising from various Fermi surface sheets corresponding to both same-sign and oppositesign order parameters 21,22 . Quasiparticle interference (QPI) due to scattering from vortex cores is, in principle, phase-sensitive, but the interpretation requires specific models of the superconducting states 23,24 . The technique of identifying bound states formed at a non-magnetic impurity by means of scanning tunnelling microscopy (STM) is more promising, and straightforward to measure.…”

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confidence: 99%

“…24. As discussed in the following, this analysis involves a minimal number of assumptions and utilizes qualitative differences between the integrated QPI intensities for the sign-changing and sign-conserving QP scatterings.…”

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confidence: 99%

“…Due to the existence of significant background QPI intensity in the region close to q = 0 we shall not consider this part as relevant for the analysis. Some of us have recently proposed 24 a new methodology for robust determination of possible order parameter sign reversal, using QPI from a single non-magnetic impurity. The central prediction is that the anti-symmetrized intensity of the real part of the FT-QPI is proportional to…”

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confidence: 99%

“…This greatly narrows the selection from various possible scenarios in the related systems 36 . We must emphasize that our present work is based on a novel theoretical proposal 24 . It would be interesting and important to do the same experiment and analysis on a system with different gaps having the same sign.…”

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confidence: 99%

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Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe

Xiong

Altenfeld

et al. 2017

Nat. Phys.

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Iron pnictides are the only known family of unconventional high-temperature superconductors besides cuprates. Until recently, it was widely accepted that superconductivity is driven by spin fluctuations and intimately related to the fermiology, specifically, hole and electron pockets separated by the same wavevector that characterizes the dominant spin fluctuations, and supporting order parameters (OP) of opposite signs 1,2 . This picture was questioned after the discovery of intercalated or monolayer form of FeSe-based systems without hole pockets, which seemingly undermines the basis for spin-fluctuation theory and the idea of a signchanging OP [3][4][5][6][7][8][9][10][11] . Using the recently proposed phase-sensitive quasiparticle interference technique, here we show that in LiOH-intercalated FeSe compound the OP does change sign, albeit within the electronic pockets. This result unifies the pairing mechanism of iron-based superconductors with or without the hole Fermi pockets and supports the conclusion that spin fluctuations play the key role in electron pairing.In iron pnictides, it has been widely perceived that superconductivity is driven by spin fluctuations, which supports the sign reversal between order parameters (OP) on the electron and hole pockets 1,2 . The discovery of superconductivity in intercalated or monolayer FeSe at a critical temperature of the order of 40 K rekindled interest in Fe-based superconductivity and sent many theorists back to the drawing board [3][4][5][6][7][8][9][10][11]

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confidence: 78%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe

Xiong

Altenfeld

et al. 2017

Nat. Phys.

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Effect of the Additional Se Layer on the Electronic Structure of Iron-Based Superconductor FeSe/SrTiO3

Tikhonova

Korshunov

2019

J Supercond Nov Magn

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We use density functional theory to study the structure and the band structure of the monolayer FeSe deposited on the SrTiO 3 substrate with the additional layer of Se between them. Top of the SrTiO 3 is formed by the double TiO layer with and without oxygen vacancies. Several structures with different arrangements of the additional Se atoms above the double TiO layer is considered. Equilibrium structures were found and the band structures for them were obtained. Near the Γ = (0, 0, 0) point of the Brillouin zone, the hole Fermi surface pockets persist and, additionally, an electron pocket appears. Thus neither the presence of the additional Se layer nor the oxygen vacancies in the double TiO layer leads to the sinking of hole bands below the Fermi level near the Γ point. Necessity to include the strong electronic correlations into account is discussed.Keywords Fe-based superconductors · Monolayer FeSe · SrTiO 3 · density functional theory 1 IntroductionIron-based materials represents a class of high-T c superconductors that is based on the conducting layer

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Synthesis methods, basic physical properties, and potential applications of the FeSe superconductor

Xu,

Xie

2024

Coordination Chemistry Reviews

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Robust determination of the superconducting gap sign structure via quasiparticle interference

Cited by 76 publications

References 40 publications

Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe

Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe

Effect of the Additional Se Layer on the Electronic Structure of Iron-Based Superconductor FeSe/SrTiO3

Synthesis methods, basic physical properties, and potential applications of the FeSe superconductor

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