Strong-coupling superconductivity in NaFe1−xCoxAs: Validity of Eliashberg theory

Guotai Tan; Ping Zheng; Xiancheng Wang; Yanchao Chen; Xiaotian Zhang; Jianlin Luo; Tucker Netherton; Yu Song; Pengcheng Dai; Chenglin Zhang; Shiliang Li

doi:10.1103/PhysRevB.87.144512

Strong-coupling superconductivity in NaFe1−xCoxAs: Validity of Eliashberg theory

Guotai Tan, Ping Zheng, Xiancheng Wang, Yanchao Chen, Xiaotian Zhang, Jianlin Luo, Tucker Netherton, Yu Song, Pengcheng Dai, Chenglin Zhang, Shiliang Li

DOI 10.1103/PhysRevB.87.144512 · Physical Review B

T1

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Abstract

We study the normal-state and superconducting properties of the NaFe1−xCoxAs system by specific heat measurements. Both the normal-state Sommerfeld coefficient and superconducting condensation energy are strongly suppressed in the underdoped and heavily overdoped samples. The low-temperature electronic specific heat can be well fitted by either a one-gap or a two-gap BCS-type function for all the superconducting samples. The ratio γNTc2/Hc2(0) can nicely associate the neutron spin resonance as the bosons in the standard Eliashberg model. However, the value of ΔC/TcγN near optimal doping is larger than the maximum value the model can obtain. Our results suggest that the high-Tc superconductivity in the Fe-based superconductors may be understood within the framework of boson-exchange mechanism but significant modification may be needed to account for the finite-temperature properties.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NaFe1-xCoxAs Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Ba0.6K0.4Fe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
NaFe0.955Co0.045As Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Ba(Fe1-xCox)2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown