Emergent phases of nodeless and nodal superconductivity separated by antiferromagnetic order in iron-based superconductor (Ca4Al2O6)Fe2(As1−xPx)2: 75As- and 31P-NMR studies

H. Kinouchi; H. Mukuda; Y. Kitaoka; P. M. Shirage; H. Fujihisa; Y. Gotoh; H. Eisaki; A. Iyo

doi:10.1103/PhysRevB.87.121101

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Emergent phases of nodeless and nodal superconductivity separated by antiferromagnetic order in iron-based superconductor (Ca4Al2O6)Fe2(As1−xPx)2: 75As- and 31P-NMR studies

H. Kinouchi, H. Mukuda, Y. Kitaoka, P. M. Shirage, H. Fujihisa, Y. Gotoh, H. Eisaki, A. Iyo

DOI 10.1103/PhysRevB.87.121101 · Physical Review B

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Abstract

We report 31P- and 75As-NMR studies on (Ca4Al2O6)Fe2(As1−xPx)2 with an isovalent substitution of P for As. We present the novel evolution of emergent phases that the nodeless superconductivity (SC) in 0≤x≤0.4 and the nodal one around x=1 are intimately separated by the onset of a commensurate stripe-type antiferromagnetic (AFM) order in 0.5≤x≤0.95, as an isovalent substitution of P for As decreases a pnictogen height hPn measured from the Fe plane. It is demonstrated that the AFM order takes place under a condition of 1.32Å≤hPn≤1.42Å, which is also the case for other Fe pnictides with the Fe2+ state in (FePn)− layers. This novel phase evolution with the variation in hPn points to the importance of electron correlation for the emergence of SC as well as AFM order.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(Ca4Al2O6)Fe2(As1-xPx)2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	27	Pressure not reported	onset
(Ca4Al2O6)Fe2P2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	17	Pressure not reported	onset
LiFeAs Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
BaFe2(As1-xPx)2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown