Neutron-irradiation effects in polycrystalline<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>LaFeAsO</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.9</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mtext>F</mml:mtext><mml:mrow><mml:mn>0.1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>superconductors

Kar’kin, A. E.; Werner, J.; Behr, G.; Goshchitskii, B. N.

doi:10.1103/physrevb.80.174512

Cited by 40 publications

(59 citation statements)

References 22 publications

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“…With decreasing temperature an upturn emerges in the curves with x in the range 0.05-0.36 that are characterized by resistivity values exceeding 1 mΩ cm around 50 K . Similar upturns have been often observed in 1111 compounds, in which disorder has been introduced with substitution at Fe site 10,15,26 and by means of irradiation 27,28 , and in Fe(Te,Se) 29 . In NdFeAs(OF) irradiated with alpha particles 28 and in Fe(Te,Se) 29 the upturn is logarithmic and the magnetoresistance is negative that strongly suggests Kondo type scattering with magnetic impurities.…”

Section: Normal State Properties (A) Resistivitysupporting

confidence: 77%

“…We obtain g c ≈0.7 and g c ≈0.3 as extracted by MR and H c2 respectively. These values are rather small in comparison with those estimated in irradiated Nd-1111 28 and La-1111 27 , Co doped Nd-1111 10 and Co doped La-1111 10 . Indeed previous reports 10,27 extract the scattering rate from H μ that strongly underestimates the actual mobility, while in Ref.…”

Section: Ii) Role Of Disordercontrasting

confidence: 71%

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Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
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In this work we present a systematic experimental and theoretical study of the structural, transport and superconducting properties of Sm(Fe 1-x Ru x )As (O 0.85 F 0.15 ) polycrystalline samples as a function of Ru content (x) ranging from 0 to 1. The choice of Ru as isoelectronic substitution at Fe site of Fdoped compounds allows to better clarify the role of structural disorder in modifying the normal and superconducting properties of these newly discovered multiband superconductors. Two different regions are identified: the Fe-rich phase (x<0.5) where superconducting and normal state properties are strongly affected by disorder induced by Ru substitution; the Ru-rich phase (x>0.5) where the system is metallic and strongly compensated and the presence of Ru frustrates the magnetic moment on Fe ions. Here the lack of magnetic features and related spin fluctuations may be the cause for the suppression of superconductivity. 1.IntroductionThe recent discovery of high critical temperature superconductivity in iron based compounds 1 has attracted a great deal of attention as these compounds appear to be a glaring case of proximity between superconductivity and magnetisms. The parent compounds exhibit antiferromagnetic spindensity-wave (SDW) order that disappears upon doping, giving rise to superconductivity. It has been suggested by many authors that superconductivity in pnictides could be mediated by magnetic excitations which couple electron and hole pockets of the Fermi surface, favoring s-wave order parameters with opposite sign on different sheets of the Fermi surface (s ± coupling). 2The interplay between superconductivity and magnetisms can be investigated by varying magnetic and superconducting properties of the compounds through suitable substitutions. Moreover, scattering induced by substitutions is expected to affect superconductivity in very differently ways in the cases of conventional or unconventional coupling. 3 As a consequence, a thorough study of the behavior of T c vs structural disorder is crucial in order to probe different theoretical models. Similarly to cuprates, the pnictide compounds have a layered structure characterized by the stacking of insulating and FeAs-conducting layers with general formulas REFeAsO (RE being a rare earth)

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Section: Normal State Properties (A) Resistivitysupporting

confidence: 77%

Section: Ii) Role Of Disordercontrasting

confidence: 71%

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
View full text Add to dashboard Cite

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“…9,[15][16][17][18][19] The result seems to be consistent with those of studies carried out by neutron 20) and α-particle 21) irradiations. Onari and Kontani have pointed out from the theoretical side that the above data of doping effects cannot be explained by the pair breaking of nonmagnetic impurities.…”

supporting

confidence: 81%

Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO_0.89F_0.11

et al. 2010

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The transport behavior and superconducting transition temperature T c of NdFe 1-y Ru y AsO 0.89 F 0.11 have been studied for various y values. Because Ru impurities are isoelectronic to host Fe atoms, we basically expect that the number of electrons does not change with y, at least in the region of small y values. The results indicate that the rate of T c suppression by Ru atoms is too small to be explained by the pair breaking effect of nonmagnetic impurities expected for the S ± symmetry, confirming our previous results for Co doping. , various studies have been carried out to identify the symmetry of their superconducting order parameter ∆. In many of these studies, much effort has been made to find experimental evidence for the S ± symmetry proposed theoretically at the early stage of the study.2, 3) For such a symmetry, reflecting the sign difference between the order parameters on disconnected Fermi surfaces around the Γ [= (0, 0)] and M [= (π, 0)] points in the reciprocal space, important features can be expected in several observable physical quantities: Neutron inelastic scattering measurements have been carried out to find the so-called "resonance peak" in the magnetic excitation spectra χ"(Q, ω)4-6) expected in the superconducting phase around a point in the scattering vector(Q)-energy(ω) space, 7,8) and an observed peak has been discussed in relation to the "resonance peak". After the confirmation of the singlet state of Cooper pairs by Knight-shift measurements, 9, 10) the temperature (T) dependence of the NMR longitudinal relaxation rate 1/T 1 has been extensively discussed, and the absence of the coherence peak has been pointed out by many research groups.11-15) The T dependence described by the relation 1/T 1 ∝T n with n∼3 has been reported below T c in almost the entire T region studied for LaFeAsO 1-x F x 11, 13,14) and LaFeAsO 1-δ .12) These results have been discussed to be favorable for the S ± symmetry.The effects of impurity doping can provide information on the relative signs of the order parameters on Fermi surfaces around the Γ and M points, and on the basis of Co doping studies, we have emphasized that the observed rate of T c decrease due to the doping of nonmagnetic impurities is too small to be explained by the pair breaking effect expected for the S ± symmetry of the order parameter. 9,[15][16][17][18][19] The result seems to be consistent with those of studies carried out by neutron 20) and α-particle 21) irradiations. Onari and Kontani have pointed out from the theoretical side that the above data of doping effects cannot be explained by the pair breaking of nonmagnetic impurities. 22) Regarding the magnetic excitation spectra χ"(Q, ω), it has been pointed 23) out that a "peak" in χ"(Q, ω) is also expected for the S symmetry of the order parameter, which has no sign difference between the Fermi surfaces around the Γ and M points, suggesting that we have to be careful in arguing whether the observed data really indicate the existence of the "resonance peak". On the T dependence of...

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“…This hierarchy of scattering rates in iron pnictides is also supported by experiment [29][30][31] . Without loss of generality we may assume s-wave scattering which corresponds to δ-correlated disorder when considering the scattering in one band.…”

Section: B Disordersupporting

confidence: 56%

“…In case of s +− pairing, this is caused by interband scattering processes 38,39 . The suppression of the SC transition temperature is an order of magnitude smaller than theoretical prediction based on the scattering rates obtained from transport experiments [29][30][31] . Hence the interband scattering rate τ 12 −1 that leads to suppression of T c is smaller than the intraband scattering rate in the band that dominates the transport properties.…”

Section: B Disordermentioning

confidence: 76%

Effect of weak disorder on the phase competition in iron pnictides

2014

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We analyze the effect of weak disorder on the competition between antiferromagnetic order and superconductivity in a model for iron-based superconductors. Under the assumption of an approximate particle-hole symmetry we show that conventional s ++ superconductivity cannot be realized in the case of coexisting magnetic and superconductive orders, observed experimentally at intermediate doping levels. This result holds for arbitrary impurity concentrations, and, in particular, in the clean limit. The inclusion of disorder further amplifies the phase competition between itinerant antiferromagnetism and conventional superconductivity. In addition, we analyze the effect of disorder on the characteristic length scales of the two order parameters, and find that in a disordered sample the staggered moment fluctuates on shorter scales than the superconductive order parameter, even if both length scales are the same in the clean limit.

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Neutron-irradiation effects in polycrystallineLaFeAsO0.9F0.1superconductors

Cited by 40 publications

References 22 publications

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
View full text Add to dashboard Cite

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
View full text Add to dashboard Cite

Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO_0.89F_0.11

Effect of weak disorder on the phase competition in iron pnictides

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Neutron-irradiation effects in polycrystallineLaFeAsO0.9F0.1superconductors

Cited by 40 publications

References 22 publications

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85FTropeano1, Cimberle2, Ferdeghini3 et al. 2010Phys. Rev. B6810951View full textAdd to dashboardCite

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85FTropeano1, Cimberle2, Ferdeghini3 et al. 2010Phys. Rev. B6810951View full textAdd to dashboardCite

Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO0.89F0.11

Effect of weak disorder on the phase competition in iron pnictides

Contact Info

Product

Resources

About

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
View full text Add to dashboard Cite

Isoelectronic Ru substitution at the iron site inSmFe1−xRuxAsO0.85F
Tropeano
¹
,
Cimberle
²
,
Ferdeghini
³

et al. 2010
Phys. Rev. B
68
10
95
1
View full text Add to dashboard Cite

Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO_0.89F_0.11