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Magnetism, superconductivity, and pairing symmetry in iron-based superconductors

TL;DR: In this paper, the antiferromagnetism and superconductivity in novel Fe-based superconductors were analyzed in the itinerant model of small electron and hole pockets near 0,0 and, respectively, and the effective interactions in both channels logarithmically flow toward the same values at low energies.
Abstract: We analyze antiferromagnetism and superconductivity in novel Fe-based superconductors within the itinerant model of small electron and hole pockets near 0,0 and ,. We argue that the effective interactions in both channels logarithmically flow toward the same values at low energies; i.e., antiferromagnetism and superconductivity must be treated on equal footing. The magnetic instability comes first for equal sizes of the two pockets, but loses to superconductivity upon doping. The superconducting gap has no nodes, but changes sign between the two Fermi surfaces extended s-wave symmetry. We argue that the T dependencies of the spin susceptibility and NMR relaxation rate for such a state are exponential only at very low T, and can be well fitted by power laws over a wide T range below Tc.
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Journal ArticleDOI
TL;DR: The response of the worldwide scientific community to the discovery in 2008 of superconductivity at T c'='26'K in the Fe-based compound LaFeAsO1−x F x has been very enthusiastic.
Abstract: The response of the worldwide scientific community to the discovery in 2008 of superconductivity at T c = 26 K in the Fe-based compound LaFeAsO1−x F x has been very enthusiastic. In short order, ot...

1,373 citations

Journal ArticleDOI
TL;DR: A detailed review of the superconductivity of FePnictide and chalcogenide (FePn/Ch) superconductors can be found in this paper.
Abstract: Kamihara and coworkers' report of superconductivity at ${T}_{c}=26\text{ }\text{ }\mathrm{K}$ in fluorine-doped LaFeAsO inspired a worldwide effort to understand the nature of the superconductivity in this new class of compounds. These iron pnictide and chalcogenide (FePn/Ch) superconductors have Fe electrons at the Fermi surface, plus an unusual Fermiology that can change rapidly with doping, which lead to normal and superconducting state properties very different from those in standard electron-phonon coupled ``conventional'' superconductors. Clearly, superconductivity and magnetism or magnetic fluctuations are intimately related in the FePn/Ch, and even coexist in some. Open questions, including the superconducting nodal structure in a number of compounds, abound and are often dependent on improved sample quality for their solution. With ${T}_{c}$ values up to 56 K, the six distinct Fe-containing superconducting structures exhibit complex but often comparable behaviors. The search for correlations and explanations in this fascinating field of research would benefit from an organization of the large, seemingly disparate data set. This review provides an overview, using numerous references, with a focus on the materials and their superconductivity.

1,349 citations

Journal ArticleDOI
TL;DR: The surprising discovery of high-temperature superconductivity in a material containing a strong magnet (iron) has led to thousands of publications as discussed by the authors, and it becomes clear what we know and where we are headed.
Abstract: The surprising discovery of high-temperature superconductivity in a material containing a strong magnet—iron—has led to thousands of publications. By placing all the data in context, it becomes clear what we know and where we are headed.

1,224 citations


Cites background from "Magnetism, superconductivity, and p..."

  • ...te (~T3) power laws, while consistent with a 2D line node model, can also arise in a symmetry s± model that accounts for disorder scattering, with exponential behavior in 1/T 1 expected only at low-T [108]. Measurements of thermal conductivity at temperatures approaching absolute zero are one of the best bulk-probe techniques for studying low-lying quasiparticle excitations in a superconductor, with th...

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Journal ArticleDOI
TL;DR: In this paper, the current theoretical and experimental state of the field of nematic order in superconductors is discussed and a review of the current literature is given. But beyond this, there is little consensus on how nematic ordering arises and whether it has an effect on superconductivity.
Abstract: Nematic order in the iron-based superconductors breaks the symmetry between the x and y directions in the Fe plane. Beyond this, however, there is little consensus on how nematic order arises and whether it has an effect on superconductivity. This Review discusses the current theoretical and experimental state of the field.

912 citations

Journal ArticleDOI
TL;DR: In this paper, a spin fluctuation theory and the sign-changing s-wave symmetry of superconducting gap structures was proposed to account for the nonuniversality of the gap structures of FeNictide and chalcogenide superconductors.
Abstract: 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

840 citations

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