Emergent Kondo Lattice Behavior in Iron-Based Superconductors AFe_{2}As_{2} (A=K, Rb, Cs)

• Published in: Physical review letters Vol. 116; no. 14; p. 147001
• Main Authors: Wu, Y P, Zhao, D, Wang, A F, Wang, N Z, Xiang, Z J, Luo, X G, Wu, T, Chen, X H
• Format: Journal Article
• Language: English
• Published: United States 08.04.2016
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.116.147001

Here, we experimentally study the origin of d-electron heavy fermion (HF) behavior in iron-based superconductors (FeSCs) AFe_{2}As_{2} (A=K, Rb, Cs). Nuclear magnetic resonance on ^{75}As 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 AFe_{2}As_{2} (A=K, Rb, Cs) as d-electron HF superconductors.