Probing the direct factor for superconductivity in FeSe-Based Superconductors by Raman Scattering

Anmin Zhang; Xiaoli Ma; Yimeng Wang; Shanshan Sun; Bin Lei; Hechang Lei; Xianhui Chen; Xiaoqun Wang; Changfeng Chen; Qingming Zhang

doi:10.1103/PhysRevB.100.060504

Probing the direct factor for superconductivity in FeSe-Based Superconductors by Raman Scattering

Anmin Zhang, Xiaoli Ma, Yimeng Wang, Shanshan Sun, Bin Lei, Hechang Lei, Xianhui Chen, Xiaoqun Wang, Changfeng Chen, Qingming Zhang

DOI 10.1103/PhysRevB.100.060504 · Physical Review B

T1

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Abstract

The FeSe-based superconductors exhibit a wide range of critical temperature Tc under a variety of material and physical conditions, but extensive studies to date have yet to produce a consensus view on the underlying mechanism. Here we report on a systematic Raman-scattering work on intercalated FeSe superconductors Lix(NH3)yFe2Se2 and (Li,Fe)OHFeSe compared to pristine FeSe. All three crystals show an anomalous power-law temperature dependence of phonon linewidths, deviating from the standard anharmonic behavior. This intriguing phenomenon is attributed to electron-phonon coupling effects enhanced by electron correlation, as evidenced by the evolution of the A1g Raman mode. Meanwhile, an analysis of the B1g mode, which probes the out-of-plane vibration of Fe, reveals a lack of influence by previously suggested structural parameters, and instead indicates a crucial role of the joint density of states in determining Tc. These findings identify carrier doping as the direct factor driving and modulating superconductivity in FeSe-based compounds.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8	Pressure unresolved	unknown
(Li,Fe)OHFeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22	Pressure not reported	unknown
Lix(NH3)yFe2Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	44	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	14	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	37	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	48	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	100	Pressure not reported	unknown