Evolution of the phase diagram of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi mathvariant="normal">LaFeP</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mtext>−</mml:mtext><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi mathvariant="normal">As</mml:mi></mml:mrow><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mtext>−</mml:mtext><mml:mi>y</mml:mi></mml:mrow></mm

Lai, Kwing To; Takemori, Akira; Miyasaka, S.; Engetsu, F.; Mukuda, H.; Tajima, S.

doi:10.1103/physrevb.90.064504

Cited by 43 publications

(56 citation statements)

References 35 publications

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“…In ref. [12], some of the present authors have shown that the variation of λ against the bond angle α exhibits a double dome feature as in Fig.2, which is consistent with the experimental observations 7,8,10 . There, the origin of the double dome structure has been explained as follows: superconductivity is suppressed when the bond angle is increased from α ∼ 110 because the hole Fermi surface around (π, π) originating from the d xy orbital vanishes.…”

Section: A Bond Angle Dependencesupporting

confidence: 80%

“…Therefore, it was expected, from the empirical T c trend found by Lee et al 4 , that T c monotonically decreases by increasing the phosphorous content [4][5][6] . However, it has recently been revealed that another local maximum of T c (we will call this the second T c dome) exists in the high phosphorous content regime 7,8,10 . Moreover, for the non-fluorine-doped system, the antiferromagnetic phase sandwiched by the two superconducting phases were found in the finite P doping region [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

“…However, it has recently been revealed that another local maximum of T c (we will call this the second T c dome) exists in the high phosphorous content regime 7,8,10 . Moreover, for the non-fluorine-doped system, the antiferromagnetic phase sandwiched by the two superconducting phases were found in the finite P doping region [9][10][11] . In order to investigate this problem theoretically, some of the authors of the present paper have recently studied the correlation between the Fe-Pn-Fe bond angle and the spin-fluctuation-mediated superconductivity 12 .…”

Section: Introductionmentioning

confidence: 99%

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Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

et al. 2015

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Motivated by recent experiments on isovalent-doped 1111 iron-based superconductors LaFeAs1−x Px O1−y Fy and the theoretical study that followed, we investigate, within the five orbital model, the correlation between the spin fluctuation and the superconducting transition temperature, which exhibits a double dome feature upon varying the Fe-As-Fe bond angle. Around the first dome with higher Tc, the low energy spin fluctuation and Tc are not tightly correlated because the finite energy spin fluctuation also contributes to superconductivity. On the other hand, the strength of the low-energy spin fluctuation originating from the d xz/yz orbital is correlated with Tc in the second dome with lower Tc. These calculation results are consistent with recent NMR study, and hence strongly suggest that the pairing in the iron-based superconductors is predominantly caused by the multi-orbital spin fluctuation.

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Section: A Bond Angle Dependencesupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

et al. 2015

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“…1(d). On the other hand, the spectra for x=0.3 and 0.8 do not undergo such significant broadening even at low temperatures, providing evidence that both are in a x in which the re-emergent AFM-2 intervenes between the SC-1 at x < 0.4 (Wang et al 19 ) and the SC-2 at 0.7< x(Lai et al 11 ).…”

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confidence: 99%

Emergence of Novel Antiferromagnetic Order Intervening between Two Superconducting Phases in LaFe(As₁₋_xP_x)O: ³¹P-NMR Studies

et al. 2014

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Systematic31 P-NMR studies of LaFe(As1−xPx)O compounds have revealed the emergence of a novel antiferromagnetic ordered phase (AFM-2) at 0.4≤ x ≤0.7 that intervenes between two superconductivity (SC) phases. This AFM-2 phase with Néel temperature TN= 35 K for x=0.6 is in strong contrast to the AFM order (AFM-1) at x=0 exhibiting TN of 140 K. Previous 31 P-NMR studies of LaFe(As1−xPx)(O1−yFy) have revealed that Tc reaches a maximum of 24 K for x=0.6 as a result of the marked enhancement of AFM spin fluctuations at low energies due to electron doping by the flourine substitution of y=0.05 for oxygen. The reason for this unexpected result has been found in the present work, that is, the emergence of AFM-2 at 0.4 ≤ x ≤0.7 without electron doping. We note that AFM spin fluctuations arising from interband nesting on the dXZ/dY Z orbits must be a key factor for the occurrence of SC around AFM-2.Iron (Fe) oxypnictide LaFeAsO with an orthorhombic structure exhibits antiferromagnetic (AFM) order, and the substitution of F − for O 2− induces superconductivity (SC) with a maximum transition temperature of T c =26 K in LaFeAsO 1−y F y .1 The isostructural compound LaFeP(O 1−y F y ) with P substituted for As also reveals the SC transition at T c =4 -7 K, which is lower than that in the case of LaFeAs(O,F).2 In Fepnictide superconductors, T c reaches a maximum of 55 K 3, 4 when a FeAs 4 block forms a nearly regular tetrahedral structure:5 The optimal values of the As-Fe-As bonding angle (α), the height of pnictogen (h Pn ) from the Fe plane, and the a-axis length (a) are 109.5• , 5∼1.38Å, 6 and ∼3.9Å, 4 respectively. In this context, since the substitution of P for As makes the a-axis length smaller, α wider, and h Pn smaller than the optimal values for high-T c Fe pnictides, it is anticipated that T c might decrease monotonically as x increases in solid solution compounds LaFe(As 1−x P x )(O 1−y F y ). Unexpectedly, T c exhibits a nonmonotonic variation with x in LaFe(As 1−x P x )(O 1−y F y ) compounds.7-9 Previous 31 P-NMR studies of these compounds have revealed that T c reaches its respective maxima of 27 and 24 K for x=0.4 with y=0.1 and for x=0.6 with y=0.05, as a result of the marked enhancement of AFM spin fluctuations(AFMSFs) at low energies.10 The result provides clear evidence that T c is enhanced by AFMSFs at low energies even though the lattice parameters deviate from their optimum values. However, another question should be addressed: Why are AFMSFs enhanced despite the fact that the lattice parameters of the compounds are far from those of the AFM mother compound LaFeAsO.In this Letter, we report the results of our 31 P-NMR studies that a novel AFM ordered phase (AFM-2) emerges at 0.4 ≤ x ≤0.7, intervening between two SC phases (SC-1 and SC-2) in LaFe(As 1−x P x )O. The 31 P- * E-mail: mukuda@mp.es.osaka-u.ac.jp † NMR Knight shift indicates the appearance of a sharp density of states (DOS) at the Fermi level derived from a d 3Z 2 −r 2 orbit, which is less relevant with the onset of SC-2. On the other hand, AFMSF...

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“…The theoretical studies have predicted that the 1111-type FeAs and FeP systems have different Fermi surface conditions depending on the local crystal structure around the Fe site [4]. Actually, our recent studies for RFeP 1−x As x (O,F) systems (R = La, Pr and Nd) have revealed that the transport properties in the normal state and the relationship between T c and the resistivity show anomalies around x = 0.6~0.8, indicating the two different Fermi surface states and the different SC mechanisms in RFeP(O,F) and RFeAs(O,F) [33,34]. These results also have suggested that the RFeP(O,F) and RFeAs(O,F) systems have different SC gap symmetries.…”

Section: Discussionmentioning

confidence: 99%

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

2016

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Abstract:We have investigated Mn, Co and Ni substitution effects on polycrystalline samples of LaFePO 0.95 F 0.05 by resistivity and magnetoresistance measurements. In LaFe 1-x M x PO 0.95 F 0.05 (M = Mn, Co and Ni), the superconducting transition temperature (T c ) monotonously decreases with increasing the impurity doping level of x. There is a clear difference of T c suppression rates among Mn, Co and Ni doping cases, and the decreasing rate of T c by Mn doping as a magnetic impurity is larger than those by the nonmagnetic doping impurities (Co/Ni). This result indicates that in LaFePO 0.95 F 0.05 , T c is rapidly suppressed by the pair-breaking effect of magnetic impurities, and the pairing symmetry is a full-gapped s-wave. In the nonmagnetic impurity-doped systems, the residual resistivity in the normal state has nearly the same value when T c becomes zero. The residual resistivity value is almost consistent with the universal value of sheet resistance for two-dimensional superconductors, suggesting that T c is suppressed by electron localization in Co/Ni-doped LaFePO 0.95 F 0.05 .

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Evolution of the phase diagram ofLaFeP1−xAsxO1−y

Cited by 43 publications

References 35 publications

Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

Emergence of Novel Antiferromagnetic Order Intervening between Two Superconducting Phases in LaFe(As₁₋_xP_x)O: ³¹P-NMR Studies

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

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Evolution of the phase diagram ofLaFeP1−xAsxO1−y

Cited by 43 publications

References 35 publications

Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

Theoretical study of correlation between spin fluctuations andTcin isovalent-doped 1111 iron-based superconductors

Emergence of Novel Antiferromagnetic Order Intervening between Two Superconducting Phases in LaFe(As1−xPx)O: 31P-NMR Studies

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

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Emergence of Novel Antiferromagnetic Order Intervening between Two Superconducting Phases in LaFe(As₁₋_xP_x)O: ³¹P-NMR Studies