Gap symmetry and structure of Fe-based superconductors

By P. Hirschfeld, M. Korshunov, I. Mazin. 2011

919 citations recorded by the source corpus.

The recently discovered Fe-pnictide and chalcogenide superconductors display low-temperature properties suggesting superconducting gap structures which appear to vary substantially from family to family, and even within families as a function of doping or pressure. We propose that this apparent nonuniversality can actually be understood by considering the predictions of spin fluctuation theory and accounting for the peculiar electronic structure of these systems, coupled with the likely ‘sign-changing s-wave’ (s±) symmetry. We review theoretical aspects, materials properties and experimental evidence relevant to this suggestion, and discuss which further measurements would be useful to settle these issues. Satisfactoriness has to be measured by a multitude of standards, of which some, for aught we know, may fail in any given case; and what is more satisfactory than any alternative in sight, may to the end be a sum of pluses and minuses, concerning which we can only trust that by ulterior corrections and improvements a maximum of the one and a minimum of the other may some day be approached.                       William James, Meaning of Truth

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Inorganic Chemistry

View Paper: https://www.semanticscholar.org/paper/340c02a38012320e251e416f57d70f380cc5afd0

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In Condensed Matter Physics

1. E. Dagotto
2. P. Dai
3. R. Fernandes
4. J. Schmalian
5. D. Feng
6. R. Cai
7. Run-Qiu Yang
8. Li Li

In Electronic, Optical and Magnetic Materials

1. E. Dagotto
2. P. Dai
3. R. Fernandes
4. J. Schmalian
5. D. Feng
6. Xianhui Chen
7. A. Chubukov
8. Run-Qiu Yang

In Inorganic Chemistry

1. E. Dagotto
2. R. Fernandes
3. G. Stewart
4. A. Chubukov
5. J. Schmalian

Citations in the corpus

• Introduction to holographic superconductor models (2015, methodology): “Upon switching on the interband coupling between the two components, this model can describe the phenomenon of the two gaps in materials such as MgB2 (s++) [138, 139] and iron pnictides (s+−) [140, 141, 142].”
• Superconductivity in iron compounds (2011, background): “…correlations in 122 KxFe2 ySe2, while Pourret et al.’s (2011) TEP data are interpreted as showing that 11 FeTe0:6Se0:4 [unique among the FePn/Ch and in agreement with DMFT calculations (Hirschfeld, Korshunov, and Mazin, 2011)] has electronic correlations comparable in strength to the cuprates.”
• Nematic order in iron superconductors - who is in the driver's seat? (2013, background): “A popular starting point is the multi-orbital Hubbard model, which describes hopping between all Fe-As orbitals and local interactions, such as intra-band and inter-band Hubbard repulsions and Hund’s exchange [2].”
• What drives nematic order in iron-based superconductors? (2014, methodology): “If the structural transition is driven not by the lattice but by some other electronic degree of freedom, equation (2) provides a natural way to connect the shear modulus to the electronic nematic susceptibility χ1.”
• A Quantum Critical Point Lying Beneath the Superconducting Dome in Iron Pnictides (2013, background): “The superconducting gap structure in the 122 family has been studied extensively by means of various experimental techniques [9].”
• Magnetism and its microscopic origin in iron-based high-temperature superconductors (2012, background): “In these cases, electronic band structure calculations have revealed that their Fermi Surfaces (FS) are composed of nearly cylindrical hole and electron pockets at the Γ(0, 0) and M(1, 0)/M(0, 1) points, respectively [15, 16].”
• Angle-resolved photoemission studies of quantum materials (2020, neutral): “…and Chubukov, 2016; Fernandes et al., 2014; Georges et al., 2013; Haule and Kotliar, 2009; Si et al., 2016), superconducting pairing mechanism (Bang and Stewart, 2017; Chubukov, 2012; Hirschfeld et al., 2011; Scalapino, 2012), and thin film forms of FeSCs (Lee, 2018; Pustovit and Kordyuk, 2016).”
• Colloquium: The unexpected properties of alkali metal iron selenide superconductors (2012, methodology): “Subsequent efforts unveiled superconductivity also in the doped versions of “122” compounds such as BaFe2As2, “111” compounds such as LiFeAs, and others (Johnston, 2010; Paglione and Greene, 2010; Stewart, 2011; Wang and Lee, 2011; Hirschfeld, Korshunov, and Mazin, 2011).”
• Plain s-wave superconductivity in single-layer FeSe on SrTiO3 probed by scanning tunnelling microscopy (2015, background): “It was argued that if the folded bands are weak, this pairing could be nodeless [11].”