Coexistence of superconductivity and magnetism in CaK(Fe1−xNix)4As4 as probed by 57Fe Mössbauer spectroscopy

Sergey L. Bud'ko; Vladimir G. Kogan; Ruslan Prozorov; William R. Meier; Mingyu Xu; Paul C. Canfield

doi:10.1103/PhysRevB.98.144520

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Coexistence of superconductivity and magnetism in CaK(Fe1−xNix)4As4 as probed by 57Fe Mössbauer spectroscopy

Sergey L. Bud'ko, Vladimir G. Kogan, Ruslan Prozorov, William R. Meier, Mingyu Xu, Paul C. Canfield

DOI 10.1103/PhysRevB.98.144520 · Physical Review B

T1

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Abstract

Temperature dependent Fe57 Mössbauer spectroscopy and specific heat measurements for CaK(Fe1−xNix)4As4 with x=0, 0.017, 0.033, and 0.049 are presented. No magnetic hyperfine field (i.e., no static magnetic order) down to 5.5 K was detected for x=0 and 0.017 in agreement with the absence of any additional feature below superconducting transition temperature Tc in the specific heat data. The evolution of magnetic hyperfine field with temperature was studied for x=0.033 and 0.049. The long-range magnetic order in these two compounds coexists with superconductivity. The magnetic hyperfine field Bhf (ordered magnetic moment) below Tc in CaK(Fe0.967Ni0.033)4As4 is continuously suppressed with the developing superconducting order parameter. The Bhf(T) data for CaK(Fe0.967Ni0.033)4As4 and CaK(Fe0.951Ni0.049)4As4 can be described reasonably well by Machida's model for coexistence of itinerant spin density wave magnetism and superconductivity [K. Machida, J. Phys. Soc. Jpn. 50, 2195 (1981)]. We demonstrate directly that superconductivity suppresses the spin density wave order parameter if the conditions are right, in agreement with the theoretical analysis.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
CaK(Fe1-xNix)4As4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CaK(Fe0.983Ni0.017)4As4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CaK(Fe0.967Ni0.033)4As4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	20	Pressure not reported	onset
CaK(Fe0.951Ni0.049)4As4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CaKFe4As4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown