Multiple Antiferromagnetic Spin Fluctuations and Novel Evolution of Tc in Iron-Based Superconductors LaFe(As1−xPx)(O1−yFy) Revealed by 31P-NMR Studies

Shiota, Tadashi; Mukuda, H.; Uekubo, M.; Engetsu, F.; Yashima, M.; Kitaoka, Y.; Lai, Kwing To; Usui, Hidetomo; Kuroki, Kazuhiko; Miyasaka, S.; Tajima, S.

doi:10.7566/jpsj.85.053706

Cited by 15 publications

(19 citation statements)

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“…3 In the four above-mentioned IBSs (LaFeAsO 1−x F x , LaFeAs(O 1−x H x ), LaFe(As 1−x P x )O, (Ca 4 Al 2 O 6 )Fe 2 (As 1−x P x ) 2 ), the first dome is associated with an antiferromagnetic order. 54,[56][57][58] In this work, however, FeS at ambient pressure is non-magnetic above T c and we note that the normal-state resistance curve of FeS with P around 4 GPa is quite flat at low temperature, which does not show a non-Fermi liquid behavior. Therefore, it is not clear whether the first dome in FeS comes from a magnetic QCP.…”

Section: Discussioncontrasting

confidence: 47%

“…[56][57][58] In LaFe(As 1−x P x )O, the first superconducting dome appear at 0.2 ≤ x ≤ 0.4 while the second dome emerges at x > 0.7. 56,57 As for (Ca 4 Al 2 O 6 )Fe 2 (As 1−x P x ) 2 , a nodeless superconducting phase lies between 0 ≤ x ≤ 0.4 while another nodal one is around x = 1. 58 Actually, a superconducting dome in T-P or T-x phase diagram has been commonly observed in unconventional superconductors, including heavy-fermion/cuprate/organic superconductors, and IBSs.…”

Section: Discussionmentioning

confidence: 99%

“…For the second dome in heavily doped IBSs, for instance, LaFeAs (O 1−x H x ), LaFe(As 1−x P x )O and (Ca 4 Al 2 O 6 )Fe 2 (As 1−x P x ) 2 , it is associated with an antiferromagnetic phase, 54,[56][57][58] while in LaFeAsO 1−x F x , the second superconducting dome is accompanied by a structural transition. 53 Very recently, the structural and electronic properties of FeS both at ambient condition and high pressure were theoretically studied by Tresca et al 61 They claim a topological change of the Fermi surface as a function of the pressure in FeS, 61 which may be the origin of the observed second superconducting dome in our work.…”

Section: Discussionmentioning

confidence: 99%

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Observation of two superconducting domes under pressure in tetragonal FeS

et al. 2017

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We investigate the evolution of superconductivity and structure with pressure for the new superconductor FeS (T c ≈ 4.5 K), a sulfide counterpart of FeSe. A rapid suppression of T c and vanishing of superconductivity at 4.0 GPa are observed, followed by a second superconducting dome from 5.0 to 22.3 GPa with a 30% enhancement in maximum T c . An onsite tetragonal to hexagonal phase transition occurs around 7.0 GPa, followed by a broad pressure range of phase coexistence. The residual deformed tetragonal phase is considered as the source of second superconducting dome. The observation of two superconducting domes in iron-based superconductors poses great challenges for understanding their pairing mechanism.

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Section: Discussioncontrasting

confidence: 47%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Observation of two superconducting domes under pressure in tetragonal FeS

et al. 2017

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“…2,3) In phosphorous-doped LaFeAs 1−x P x O, an AFM phase emerges at 0.4 ≤ x ≤ 0.7 because of the substitution of P 3− for As 3− . [4][5][6][7] Phosphorus doping also results in the emergence of an AFM phase in (Ca 4 Al 2 O 6 )Fe 2 (As 1−x P x ) 2 at 0.3 ≤ x ≤ 0.95. 8) In these cases of phosphorus doping, no charge carriers are introduced because phosphorus and arsenic are isovalent elements.…”

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Pressure-Induced Superconductivity from Doping-Induced Antiferromagnetic Phase of 112-type Ca₁₋_xLa_xFeAs₂

et al. 2017

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The effects of pressure on antiferromagnetic (AFM) and superconducting phase transitions of 112-type Ca 1−x La x FeAs 2 were studied, and the in-plane electrical resistivity ρ ab was measured with an indenter-type pressure cell. The AFM phase transition temperatures of T N = 47, 63, and 63 K at ambient pressure for x = 0.18, 0.21, and 0.26 was suppressed by applying pressure P, with superconductivity emerging at critical pressures of P c ≃ 0, 1.5, and 3.4 GPa, respectively. Correspondingly, the slope of T N against P decreased as dT N /P ≃ −15 and −2 K/GPa for x = 0.21 and 0.26, respectively. Thus, although the AFM phase was stabilized with La doping x, the AFM phase was suppressed by pressure, and superconductivity eventually emerged.The parent compounds of most iron-based superconductors exhibit antiferromagnetic (AFM) ordering, and superconductivity emerges with high transition temperature, T c , when the AFM phase is suppressed by pressure or chemical doping.1) Some iron-based superconductors, however, exhibit AFM ordering that is induced by pressure or chemical substitution. For example, in hydrogen-doped LaFeAsO 1−x H x , the substitution of H − for O 2− results in the suppression of superconductivity, and an AFM phase emerges at x ≥ 0.4, where the electrons are overdoped.2, 3) In phosphorous-doped LaFeAs 1−x P x O, an AFM phase emerges at 0.4 ≤ x ≤ 0.7 because of the substitution of P 3− for As 3− . 4-7) Phosphorus doping also results in the emergence of an AFM phase in (Ca 4 Al 2 O 6 )Fe 2 (As 1−x P x ) 2 at 0.3 ≤ x ≤ 0.95. 8) In these cases of phosphorus doping, no charge carriers are introduced because phosphorus and arsenic are isovalent elements. A pressure-induced AFM phase has been reported in FeSe at P ≥ 0.8 GPa.9-12) Interestingly, in FeSe, the application of higher pressures suppresses the AFM phase, and the superconducting transition temperature T c exhibits a sudden increase up to 38 K at 6 GPa. 13)Very recently, a novel iron-based superconductor exhibiting doping-induced AFM ordering has been discovered in the 112-type compound Ca 1−x La x FeAs 2 .14-18) The Ca 1−x La x FeAs 2 compound crystallizes into a monoclinic structure with space group P2 1 (No. 4, C 2 2 ) with alternately stacked FeAs and Ca 1−x La x As layers along the caxis. While the end member, or the parent compound without La doping CaFeAs 2 , was not obtained, the substitution of La for Ca stabilized the 112 phase at 0.15 ≤ x ≤ 0.27 for Ca 1−x La x FeAs 2 . The highest value of T c = 35 K has been found at x = 0. In this paper, we present the results of resistivity measurements under various pressures in Ca 1−x La x FeAs 2 with x = 0.18, 0.21, and 0.26, which exhibited AFM ordering at T N = 47, 63, and 63 K, respectively. Our results revealed that the application of pressure suppressed the AFM ordering and induced superconductivity. Thus, the AFM ordering of Ca 1−x La x FeAs 2 exhibited a "normal" response to pressure.Single crystals of Ca 1−x La x FeAs 2 were grown by heating a mixture of Ca, La, FeAs, and As powders as descr...

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“…In such a situation, Shiota and coworkers [9] have focused on LaFe(As 1−x P x )(O 1−y F y ) system and performed extensive 31 P-NMR over wide compositions for 0 < x < 1 and 0 < y < 0.14. As seen in Fig.…”

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Antiferromagnetic Spin Fluctuations; What Else?

Ishida

2016

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Multiple Antiferromagnetic Spin Fluctuations and Novel Evolution of T_c in Iron-Based Superconductors LaFe(As₁₋_xP_x)(O₁₋_yF_y) Revealed by ³¹P-NMR Studies

Cited by 15 publications

References 24 publications

Observation of two superconducting domes under pressure in tetragonal FeS

Observation of two superconducting domes under pressure in tetragonal FeS

Pressure-Induced Superconductivity from Doping-Induced Antiferromagnetic Phase of 112-type Ca₁₋_xLa_xFeAs₂

Antiferromagnetic Spin Fluctuations; What Else?

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Multiple Antiferromagnetic Spin Fluctuations and Novel Evolution of Tc in Iron-Based Superconductors LaFe(As1−xPx)(O1−yFy) Revealed by 31P-NMR Studies

Cited by 15 publications

References 24 publications

Observation of two superconducting domes under pressure in tetragonal FeS

Observation of two superconducting domes under pressure in tetragonal FeS

Pressure-Induced Superconductivity from Doping-Induced Antiferromagnetic Phase of 112-type Ca1−xLaxFeAs2

Antiferromagnetic Spin Fluctuations; What Else?

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Multiple Antiferromagnetic Spin Fluctuations and Novel Evolution of T_c in Iron-Based Superconductors LaFe(As₁₋_xP_x)(O₁₋_yF_y) Revealed by ³¹P-NMR Studies

Pressure-Induced Superconductivity from Doping-Induced Antiferromagnetic Phase of 112-type Ca₁₋_xLa_xFeAs₂