Tracing the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>s</mml:mi><mml:mo>±</mml:mo></mml:msub></mml:math>symmetry in iron pnictides by controlled disorder

Schilling, M. B.; Baumgärtner, A.; Gorshunov, B.; Жукова, Е. С.; Dravin, V. A.; Mitsen, K. V.; Efremov, D. V.; Dolgov, O. V.; Iida, K.; Dressel, Martin; Zapf, Sina

doi:10.1103/physrevb.93.174515

Cited by 35 publications

(43 citation statements)

References 35 publications

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“…the orbital fluctuations, which favors the s++ state without sign reversal 5 . A disorder-induced change from sign-reversed (s±) to sign-preserved (s++) symmetry in multi-band superconductors has been predicted 6,7 and observed 8 . Finally, nodal-like behaviors at increasing disorder was observed, e.g.…”

Section: Introductionmentioning

confidence: 99%

Effects of disorder induced by heavy-ion irradiation on (Ba1−x K x )Fe2As2 single crystals, within the three-band Eliashberg s± wave model

Ghigo

Ummarino

Gozzelino

et al. 2017

Sci Rep

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One of the open issues concerning iron-based superconductors is whether the s± wave model is able to account for the overall effects of impurity scattering, including the low rate of decrease of the critical temperature with the impurity concentration. Here we investigate Ba1−xKxFe2As2 crystals where disorder is introduced by Au-ion irradiation. Critical temperature, T c, and London penetration depth, λ L, were measured by a microwave resonator technique, for different values of the irradiation fluence. We compared experimental data with calculations made on the basis of the three-band Eliashberg equations, suitably accounting for the impurity scattering. We show that this approach is able to explain in a consistent way the effects of disorder both on T c and on λ L(T), within the s± wave model. In particular, a change of curvature in the low-temperature λ L(T) curves for the most irradiated crystals is fairly well reproduced.

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Section: Introductionmentioning

confidence: 99%

Effects of disorder induced by heavy-ion irradiation on (Ba1−x K x )Fe2As2 single crystals, within the three-band Eliashberg s± wave model

Ghigo

Ummarino

Gozzelino

et al. 2017

Sci Rep

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“…The underlying reason is the multiband character of the Fermi surfaces in the FeBSs. In this case the order parameter may change sign due to impurities, as was demonstrated theoretically [26][27][28] and experimentally [29] with doping either to d-wave symmetry [30][31][32][33] or a change of sign [34]. Therefore, a universal tool to ascertain the pairing symmetry is much needed.…”

Section: Introductionmentioning

confidence: 99%

Quasiparticle interference in multiband superconductors with strong coupling

et al. 2017

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We develop a theory of the quasiparticle interference (QPI) in multiband superconductors based on the strong-coupling Eliashberg approach within the Born approximation. In the framework of this theory, we study dependencies of the QPI response function in the multiband superconductors with the nodeless s-wave superconductive order parameter. We pay special attention to the difference in the quasiparticle scattering between the bands having the same and opposite signs of the order parameter. We show that at the momentum values close to the momentum transfer between two bands, the energy dependence of the quasiparticle interference response function has three singularities. Two of these correspond to the values of the gap functions and the third one depends on both the gaps and the transfer momentum. We argue that only the singularity near the smallest band gap may be used as a universal tool to distinguish between the s ++ and s ± order parameters. The robustness of the sign of the response function peak near the smaller gap value, irrespective of the change in parameters, in both the symmetry cases is a promising feature that can be harnessed experimentally.

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“…While the back‐shift of the coherence peak can be seen as predicted by theory, the re‐increase of

λ_{L}^{- 2}

at the critical scattering rate

Γ_{c}

is not resolved in the results (adapted from Ref. ).…”

Section: Identification Of the Symmetry Of The Order Parameter With Tmentioning

confidence: 81%

“…The evolution of the order parameter may determine the order parameter in the clean limit (small interband impurity scattering) of multiband superconductors. Following this suggestion the proton irradiation has been used to create nonmagnetic disorder in Ba(Fe 0.9 Co 0.1 ) 2 As 2 thin films . The consecutive proton irradiation of iron pnictides results in a monotonous decrease of

T_{c}

.…”

Section: Identification Of the Symmetry Of The Order Parameter With Tmentioning

confidence: 99%

A multiband Eliashberg‐approach to iron‐based superconductors

Efremov

Drechsler

Rösner

et al. 2017

Physica Status Solidi (b)

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Since the discovery of the Fe-based superconductors (FeSC) a lot of efforts has been applied to elucidate the microscopic mechanism behind cooper pairing and the symmetry of the order parameter. Examination of effective interactions of electrons with spin-fluctuations in these systems yield that couplings are not weak and the materials have to be considered in a strong coupling scheme. In the present article, we review some aspects of the description of iron-based superconductors in the frame of the Eliashberg approach for multiband systems. The application of the Eliashberg scheme is demonstrated with two compounds Ba0.6K0.4Fe2As2 and Ca0.32Na0.68Fe2As2. In both cases, it was found that these materials are in the intermediate coupling regime. Further, we consider effects of impurities on physical properties of multiband superconductors. It is demonstrated that the impurities affect nontrivially the superconducting properties. In particular, they may trigger a symmetry change of superconducting order parameters. This effect can be used for determination of the superconducting order parameter. Finally, we consider KFe2As2 and show that its thermodynamic properties are consistent with a nodal superconducting order parameter

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Tracing thes±symmetry in iron pnictides by controlled disorder

Cited by 35 publications

References 35 publications

Effects of disorder induced by heavy-ion irradiation on (Ba1−x K x )Fe2As2 single crystals, within the three-band Eliashberg s± wave model

Effects of disorder induced by heavy-ion irradiation on (Ba1−x K x )Fe2As2 single crystals, within the three-band Eliashberg s± wave model

Quasiparticle interference in multiband superconductors with strong coupling

A multiband Eliashberg‐approach to iron‐based superconductors

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