Pseudogap-less high-T
 c
 superconductivity in BaCo
 x
 Fe
 2−x
 As
 2

Massee, F.; Huang, Yingkai; Kaas, J.; Heumen, E. van; Jong, S. de; Huisman, R.; Luigjes, H.; Goedkoop, J. B.; Golden, M. S.

doi:10.1209/0295-5075/92/57012

Cited by 29 publications

(31 citation statements)

References 37 publications

(51 reference statements)

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“…The STS curves can be fit to the Dynes function [28] using a gap value of ∆ ∼12 meV, yielding the ratio 2∆/k B T c ∼ 6.3. This is consistent with reported values for other 122 Febased superconductors [29,30] and it is also expected for a moderate-coupling BCS superconductor. However, such a gap structure varies spatially; the STS curves mea- sured on the clover-like defect (see upper star in Fig.4b) show a gap size as large as 30 meV with no prominent coherence peaks (red curve in Fig.4c).…”

supporting

confidence: 93%

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

et al. 2014

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We use multi-scale techniques to determine the extent of local inhomogeneity and superconductivity in Ca0.86Pr0.14Fe2As2 single crystal. The inhomogeneity is manifested as a spatial variation of praseodymium concentration, local density of states, and superconducting order parameter. We show that the high-Tc superconductivity emerges from clover-like defects associated with Pr dopants. The highest Tc is observed in both the tetragonal and collapsed tetragonal phases, and its filamentary nature is a consequence of non-uniform Pr distribution that develops localized, isolated superconducting regions within the crystals.

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supporting

confidence: 93%

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

et al. 2014

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“…Also disordered vortices were detected showing neither localized states typical for an s-wave superconductors in the clean limit nor any internal structure predicted for d-wave vortices. Much bigger spatial variations from the averaged gap value were reported by Massee et al [21] in their STM measurements on Ba(Fe 0.93 Co 0.07 ) 2 As 2 with 2kT c spanning between 5 and 10.…”

Section: Overview Of the Superconducting Gap Studiesmentioning

confidence: 65%

Point contact Andreev reflection spectroscopy of superconducting energy gaps in 122-type family of iron pnictides

Samuely

Pribulová

Szabó

et al. 2009

Physica C: Superconductivity

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A brief overview of the superconducting energy gap studies on 122-type family of iron pnictides is given. It seems that the situation in the hole-doped Ba 1-x K x Fe 2 As 2 is well resolved. Most of the measurements including the presented here point-contact Andreev reflection spectra agree on existence of multiple nodeless gaps in the excitation spectrum of this multiband system. The gaps have basically two sizes -the small one with a strength up to the BCS weak coupling limit and the large one with a very strong coupling with 2 L kT c > 6 -8. In the electron doped Ba(Fe 1-x Co x ) 2 As 2 the most of the experiments including our point contact measurements reveal in quite broadened spectra only a single gap with a strong coupling strength. The high precision ARPES measurements on this system identified two gaps but very close to each other, both showing a strong coupling with 2kT c ~ 5 and 6, respectively.

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“…The first result in P-doped BaFe2As2 agrees in principle with the ARPES data of Shimojima et al [493] discussed above, although the values of T* disagree (90 vs 200 K). In contradiction to the second result in Co-doped BaFe2As2, Massee et al [507], using scanning tunneling spectroscopy (STS), report no evidence for a pseudogap in Ba(Fe1-xCox)2As2, x=0.04, 0.07, and 0.105.…”

Section: Optical/sts/resistivity/stmmentioning

confidence: 87%

“…26 where the magnetism ends before the start of superconductivity. Despite this, the article by Hess et al is still often cited (see, e.g., Massee et al [507] as evidence for pseudogap behavior in the IBS.…”

Section: Optical/sts/resistivity/stmmentioning

confidence: 99%

Unconventional superconductivity

Stewart

2017

Advances in Physics

221

165

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Abstract:"Conventional" superconductivity, as used in this review, refers to electron-phonon coupled superconducting electron pairs described by BCS theory. Unconventional superconductivity refers to superconductors where the Cooper pairs are not bound together by phonon-exchange but instead by exchange of some other kind, e. g. spin fluctuations in a superconductor with magnetic order either coexistent or nearby in the phase diagram. Such unconventional superconductivity has been known experimentally since heavy fermion CeCu2Si2, with its strongly correlated 4f electrons, was discovered to superconduct below 0.6 K in 1979. Since the discovery of unconventional superconductivity in the layered cuprates in 1986, the study of these materials saw Tc jump to 164 K by 1994. Further progess in high temperature superconductivity would be aided by understanding the cause of such unconventional pairing. This review compares the fundamental properties of 9 unconventional superconducting classes of materialsfrom 4f-electron heavy fermions to organic superconductors to classes where only three known members exist to the cuprates with over 200 examples -with the hope that common features will emerge to help theory explain (and predict!) these phenomena. In addition, three new emerging classes of superconductors (topological, interfacial -e. g. FeSe on SrTiO3, and H2S under high pressure) are briefly covered, even though their "conventionality" is not yet fully determined.

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Pseudogap-less high-T _c superconductivity in BaCo _x Fe _2−x As ₂

Abstract: Pseudogap-less high-Tc superconductivity in BaCoxFe2xAs2Massee, F.; Huang, Y.; Kaas, J.J.; van Heumen, E.; de Jong, S.; Huisman, R.; Luigjes, H.; Goedkoop, J.B.; Golden, M.S.

Cited by 29 publications

References 37 publications

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

Point contact Andreev reflection spectroscopy of superconducting energy gaps in 122-type family of iron pnictides

Unconventional superconductivity

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Pseudogap-less high-T c superconductivity in BaCo x Fe 2−x As 2

Abstract: Pseudogap-less high-Tc superconductivity in BaCoxFe2xAs2Massee, F.; Huang, Y.; Kaas, J.J.; van Heumen, E.; de Jong, S.; Huisman, R.; Luigjes, H.; Goedkoop, J.B.; Golden, M.S.

Cited by 29 publications

References 37 publications

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

Local Inhomogeneity and Filamentary Superconductivity in Pr-DopedCaFe2As2

Point contact Andreev reflection spectroscopy of superconducting energy gaps in 122-type family of iron pnictides

Unconventional superconductivity

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Pseudogap-less high-T _c superconductivity in BaCo _x Fe _2−x As ₂