Emergent Kondo Lattice Behavior in Iron-Based Superconductors AFe2As2 (A=K, Rb, Cs)

Y. P. Wu; D. Zhao; A. F. Wang; N. Z. Wang; Z. J. Xiang; X. G. Luo; T. Wu; X. H. Chen

doi:10.1103/PhysRevLett.116.147001

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Emergent Kondo Lattice Behavior in Iron-Based Superconductors AFe2As2 (A=K, Rb, Cs)

Y. P. Wu, D. Zhao, A. F. Wang, N. Z. Wang, Z. J. Xiang, X. G. Luo, T. Wu, X. H. Chen

DOI 10.1103/PhysRevLett.116.147001 · Physical Review Letters

T1

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Abstract

Here, we experimentally study the origin of d-electron heavy fermion (HF) behavior in iron-based superconductors (FeSCs) AFe2As2 (A=K, Rb, Cs). Nuclear magnetic resonance on As75 reveals a universal coherent-incoherent crossover with a characteristic temperature T*. Below T*, a so-called “Knight shift anomaly” is first observed in FeSCs, which exhibits a scaling behavior similar to f-electron HF materials. Furthermore, the scaling rule also regulates the manifestation of magnetic fluctuation. These results undoubtedly support an emergent Kondo lattice scenario for the d-electron HF behavior, which qualifies the AFe2As2 (A=K, Rb, Cs) as d-electron HF superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
RbFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CsFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown